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b84e739cfa624b2a953d4bbf0cfe69662ab48817
MaxScale/server/modules/routing/readwritesplit/readwritesplit.c
Markus Makela b84e739cfa All queries related to prepared statement are sent to the master 
The preparation and closing of prepared statements was sent to all servers
even though the execution was always sent to the master. With this change,
all queries which interact with prepared statements are only sent to the master.

The sending of statement preparations to all servers is a problem when a
statement which depends on a database or a table is created and the DDL
statement which created that table has not yet been replicated to the
slaves.

In addition to fixing the aforementioned problem, this change should also
reduce unnecessary network traffic to slaves and improve the overall
performance of the prepared statements.
2016-01-08 11:16:30 +02:00

5367 lines
169 KiB
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/*
* This file is distributed as part of the MariaDB Corporation MaxScale. It is free
* software: you can redistribute it and/or modify it under the terms of the
* GNU General Public License as published by the Free Software Foundation,
* version 2.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Copyright MariaDB Corporation Ab 2013-2014
*/
#include <my_config.h>
#include <stdio.h>
#include <strings.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <router.h>
#include <readwritesplit.h>
#include <mysql.h>
#include <skygw_utils.h>
#include <log_manager.h>
#include <query_classifier.h>
#include <dcb.h>
#include <spinlock.h>
#include <modinfo.h>
#include <modutil.h>
#include <mysql_client_server_protocol.h>
MODULE_INFO info = {
MODULE_API_ROUTER,
MODULE_GA,
ROUTER_VERSION,
"A Read/Write splitting router for enhancement read scalability"
};
#if defined(SS_DEBUG)
# include <mysql_client_server_protocol.h>
#endif
#define RWSPLIT_TRACE_MSG_LEN 1000
/**
* @file readwritesplit.c The entry points for the read/write query splitting
* router module.
*
* This file contains the entry points that comprise the API to the read write
* query splitting router.
* @verbatim
* Revision History
*
* Date Who Description
* 01/07/2013 Vilho Raatikka Initial implementation
* 15/07/2013 Massimiliano Pinto Added clientReply
* from master only in case of session change
* 17/07/2013 Massimiliano Pinto clientReply is now used by mysql_backend
* for all reply situations
* 18/07/2013 Massimiliano Pinto routeQuery now handles COM_QUIT
* as QUERY_TYPE_SESSION_WRITE
* 17/07/2014 Massimiliano Pinto Server connection counter is updated in closeSession
*
* 09/09/2015 Martin Brampton Modify error handler
* 25/09/2015 Martin Brampton Block callback processing when no router session in the DCB
*
* @endverbatim
*/
static char *version_str = "V1.0.2";
static ROUTER* createInstance(SERVICE *service, char **options);
static void* newSession(ROUTER *instance, SESSION *session);
static void closeSession(ROUTER *instance, void *session);
static void freeSession(ROUTER *instance, void *session);
static int routeQuery(ROUTER *instance, void *session, GWBUF *queue);
static void diagnostic(ROUTER *instance, DCB *dcb);
static void clientReply(
ROUTER* instance,
void* router_session,
GWBUF* queue,
DCB* backend_dcb);
static void handleError(
ROUTER* instance,
void* router_session,
GWBUF* errmsgbuf,
DCB* backend_dcb,
error_action_t action,
bool* succp);
static void print_error_packet(ROUTER_CLIENT_SES* rses, GWBUF* buf, DCB* dcb);
static int router_get_servercount(ROUTER_INSTANCE* router);
static int rses_get_max_slavecount(ROUTER_CLIENT_SES* rses, int router_nservers);
static int rses_get_max_replication_lag(ROUTER_CLIENT_SES* rses);
static backend_ref_t* get_bref_from_dcb(ROUTER_CLIENT_SES* rses, DCB* dcb);
static DCB* rses_get_client_dcb(ROUTER_CLIENT_SES* rses);
static route_target_t get_route_target (
skygw_query_type_t qtype,
bool trx_active,
bool load_active,
target_t use_sql_variables_in,
HINT* hint);
static backend_ref_t* check_candidate_bref(
backend_ref_t* candidate_bref,
backend_ref_t* new_bref,
select_criteria_t sc);
static skygw_query_type_t is_read_tmp_table(
ROUTER_CLIENT_SES* router_cli_ses,
GWBUF* querybuf,
skygw_query_type_t type);
static void check_create_tmp_table(
ROUTER_CLIENT_SES* router_cli_ses,
GWBUF* querybuf,
skygw_query_type_t type);
static bool route_single_stmt(
ROUTER_INSTANCE* inst,
ROUTER_CLIENT_SES* rses,
GWBUF* querybuf);
static int getCapabilities();
#if defined(NOT_USED)
static bool router_option_configured(
ROUTER_INSTANCE* router,
const char* optionstr,
void* data);
#endif
#if defined(PREP_STMT_CACHING)
static prep_stmt_t* prep_stmt_init(prep_stmt_type_t type, void* id);
static void prep_stmt_done(prep_stmt_t* pstmt);
#endif /*< PREP_STMT_CACHING */
int bref_cmp_global_conn(
const void* bref1,
const void* bref2);
int bref_cmp_router_conn(
const void* bref1,
const void* bref2);
int bref_cmp_behind_master(
const void* bref1,
const void* bref2);
int bref_cmp_current_load(
const void* bref1,
const void* bref2);
/**
* The order of functions _must_ match with the order the select criteria are
* listed in select_criteria_t definition in readwritesplit.h
*/
int (*criteria_cmpfun[LAST_CRITERIA])(const void*, const void*)=
{
NULL,
bref_cmp_global_conn,
bref_cmp_router_conn,
bref_cmp_behind_master,
bref_cmp_current_load
};
static bool select_connect_backend_servers(
backend_ref_t** p_master_ref,
backend_ref_t* backend_ref,
int router_nservers,
int max_nslaves,
int max_rlag,
select_criteria_t select_criteria,
SESSION* session,
ROUTER_INSTANCE* router);
static bool get_dcb(
DCB** dcb,
ROUTER_CLIENT_SES* rses,
backend_type_t btype,
char* name,
int max_rlag);
static void rwsplit_process_router_options(
ROUTER_INSTANCE* router,
char** options);
static ROUTER_OBJECT MyObject = {
createInstance,
newSession,
closeSession,
freeSession,
routeQuery,
diagnostic,
clientReply,
handleError,
getCapabilities
};
static bool rses_begin_locked_router_action(
ROUTER_CLIENT_SES* rses);
static void rses_end_locked_router_action(
ROUTER_CLIENT_SES* rses);
static void mysql_sescmd_done(
mysql_sescmd_t* sescmd);
static mysql_sescmd_t* mysql_sescmd_init (
rses_property_t* rses_prop,
GWBUF* sescmd_buf,
unsigned char packet_type,
ROUTER_CLIENT_SES* rses);
static rses_property_t* mysql_sescmd_get_property(
mysql_sescmd_t* scmd);
static rses_property_t* rses_property_init(
rses_property_type_t prop_type);
static int rses_property_add(
ROUTER_CLIENT_SES* rses,
rses_property_t* prop);
static void rses_property_done(
rses_property_t* prop);
static mysql_sescmd_t* rses_property_get_sescmd(
rses_property_t* prop);
static bool execute_sescmd_history(backend_ref_t* bref);
static bool execute_sescmd_in_backend(
backend_ref_t* backend_ref);
static void sescmd_cursor_reset(sescmd_cursor_t* scur);
static bool sescmd_cursor_history_empty(sescmd_cursor_t* scur);
static void sescmd_cursor_set_active(
sescmd_cursor_t* sescmd_cursor,
bool value);
static bool sescmd_cursor_is_active(
sescmd_cursor_t* sescmd_cursor);
static GWBUF* sescmd_cursor_clone_querybuf(
sescmd_cursor_t* scur);
static mysql_sescmd_t* sescmd_cursor_get_command(
sescmd_cursor_t* scur);
static bool sescmd_cursor_next(
sescmd_cursor_t* scur);
static GWBUF* sescmd_cursor_process_replies(GWBUF* replybuf, backend_ref_t* bref,bool*);
static void tracelog_routed_query(
ROUTER_CLIENT_SES* rses,
char* funcname,
backend_ref_t* bref,
GWBUF* buf);
static bool route_session_write(
ROUTER_CLIENT_SES* router_client_ses,
GWBUF* querybuf,
ROUTER_INSTANCE* inst,
unsigned char packet_type,
skygw_query_type_t qtype);
static void refreshInstance(
ROUTER_INSTANCE* router,
CONFIG_PARAMETER* param);
static void bref_clear_state(backend_ref_t* bref, bref_state_t state);
static void bref_set_state(backend_ref_t* bref, bref_state_t state);
static sescmd_cursor_t* backend_ref_get_sescmd_cursor (backend_ref_t* bref);
static int router_handle_state_switch(DCB* dcb, DCB_REASON reason, void* data);
static bool handle_error_new_connection(
ROUTER_INSTANCE* inst,
ROUTER_CLIENT_SES** rses,
DCB* backend_dcb,
GWBUF* errmsg);
static void handle_error_reply_client(
SESSION* ses,
ROUTER_CLIENT_SES* rses,
DCB* backend_dcb,
GWBUF* errmsg);
static backend_ref_t* get_root_master_bref(ROUTER_CLIENT_SES* rses);
static BACKEND* get_root_master(
backend_ref_t* servers,
int router_nservers);
static bool have_enough_servers(
ROUTER_CLIENT_SES** rses,
const int nsrv,
int router_nsrv,
ROUTER_INSTANCE* router);
static SPINLOCK instlock;
static ROUTER_INSTANCE* instances;
static int hashkeyfun(void* key);
static int hashcmpfun (void *, void *);
static int hashkeyfun(
void* key)
{
if(key == NULL){
return 0;
}
unsigned int hash = 0,c = 0;
char* ptr = (char*)key;
while((c = *ptr++)){
hash = c + (hash << 6) + (hash << 16) - hash;
}
return hash;
}
static int hashcmpfun(
void* v1,
void* v2)
{
char* i1 = (char*) v1;
char* i2 = (char*) v2;
return strcmp(i1,i2);
}
static void* hstrdup(void* fval)
{
char* str = (char*)fval;
return strdup(str);
}
static void* hfree(void* fval)
{
free (fval);
return NULL;
}
/**
* Implementation of the mandatory version entry point
*
* @return version string of the module
*/
char *
version()
{
return version_str;
}
/**
* The module initialisation routine, called when the module
* is first loaded.
*/
void
ModuleInit()
{
MXS_NOTICE("Initializing statemend-based read/write split router module.");
spinlock_init(&instlock);
instances = NULL;
}
/**
* The module entry point routine. It is this routine that
* must populate the structure that is referred to as the
* "module object", this is a structure with the set of
* external entry points for this module.
*
* @return The module object
*/
ROUTER_OBJECT* GetModuleObject()
{
return &MyObject;
}
/**
* Refresh the instance by the given parameter value.
*
* @param router Router instance
* @param singleparam Parameter fo be reloaded
*
* Note: this part is not done. Needs refactoring.
*/
static void refreshInstance(
ROUTER_INSTANCE* router,
CONFIG_PARAMETER* singleparam)
{
CONFIG_PARAMETER* param;
bool refresh_single;
config_param_type_t paramtype;
if (singleparam != NULL)
{
param = singleparam;
refresh_single = true;
}
else
{
param = router->service->svc_config_param;
refresh_single = false;
}
paramtype = config_get_paramtype(param);
while (param != NULL)
{
/** Catch unused parameter types */
ss_dassert(paramtype == COUNT_TYPE ||
paramtype == PERCENT_TYPE ||
paramtype == SQLVAR_TARGET_TYPE);
if (paramtype == COUNT_TYPE)
{
if (strncmp(param->name, "max_slave_connections", MAX_PARAM_LEN) == 0)
{
int val;
bool succp;
router->rwsplit_config.rw_max_slave_conn_percent = 0;
succp = config_get_valint(&val, param, NULL, paramtype);
if (succp)
{
router->rwsplit_config.rw_max_slave_conn_count = val;
}
}
else if (strncmp(param->name,
"max_slave_replication_lag",
MAX_PARAM_LEN) == 0)
{
int val;
bool succp;
succp = config_get_valint(&val, param, NULL, paramtype);
if (succp)
{
router->rwsplit_config.rw_max_slave_replication_lag = val;
}
}
}
else if (paramtype == PERCENT_TYPE)
{
if (strncmp(param->name, "max_slave_connections", MAX_PARAM_LEN) == 0)
{
int val;
bool succp;
router->rwsplit_config.rw_max_slave_conn_count = 0;
succp = config_get_valint(&val, param, NULL, paramtype);
if (succp)
{
router->rwsplit_config.rw_max_slave_conn_percent = val;
}
}
}
else if (paramtype == SQLVAR_TARGET_TYPE)
{
if (strncmp(param->name,
"use_sql_variables_in",
MAX_PARAM_LEN) == 0)
{
target_t valtarget;
bool succp;
succp = config_get_valtarget(&valtarget, param, NULL, paramtype);
if (succp)
{
router->rwsplit_config.rw_use_sql_variables_in = valtarget;
}
}
}
if (refresh_single)
{
break;
}
param = param->next;
}
#if defined(NOT_USED) /*< can't read monitor config parameters */
if ((*router->servers)->backend_server->rlag == -2)
{
rlag_enabled = false;
}
else
{
rlag_enabled = true;
}
/**
* If replication lag detection is not enabled the measure can't be
* used in slave selection.
*/
if (!rlag_enabled)
{
if (rlag_limited)
{
MXS_WARNING("Configuration Failed, max_slave_replication_lag "
"is set to %d,\n\t\t but detect_replication_lag "
"is not enabled. Replication lag will not be checked.",
router->rwsplit_config.rw_max_slave_replication_lag);
}
if (router->rwsplit_config.rw_slave_select_criteria ==
LEAST_BEHIND_MASTER)
{
MXS_WARNING("Configuration Failed, router option "
"\n\t\t slave_selection_criteria=LEAST_BEHIND_MASTER "
"is specified, but detect_replication_lag "
"is not enabled.\n\t\t "
"slave_selection_criteria=%s will be used instead.",
STRCRITERIA(DEFAULT_CRITERIA));
router->rwsplit_config.rw_slave_select_criteria =
DEFAULT_CRITERIA;
}
}
#endif /*< NOT_USED */
}
/**
* Create an instance of read/write statement router within the MaxScale.
*
*
* @param service The service this router is being create for
* @param options The options for this query router
*
* @return NULL in failure, pointer to router in success.
*/
static ROUTER *
createInstance(SERVICE *service, char **options)
{
ROUTER_INSTANCE* router;
SERVER* server;
SERVER_REF* sref;
int nservers;
int i;
CONFIG_PARAMETER* param;
char *weightby;
if ((router = calloc(1, sizeof(ROUTER_INSTANCE))) == NULL) {
return NULL;
}
router->service = service;
spinlock_init(&router->lock);
/** Calculate number of servers */
sref = service->dbref;
nservers = 0;
while (sref != NULL)
{
nservers++;
sref=sref->next;
}
router->servers = (BACKEND **)calloc(nservers + 1, sizeof(BACKEND *));
if (router->servers == NULL)
{
free(router);
return NULL;
}
/**
* Create an array of the backend servers in the router structure to
* maintain a count of the number of connections to each
* backend server.
*/
sref = service->dbref;
nservers= 0;
while (sref != NULL) {
if ((router->servers[nservers] = malloc(sizeof(BACKEND))) == NULL)
{
/** clean up */
for (i = 0; i < nservers; i++) {
free(router->servers[i]);
}
free(router->servers);
free(router);
return NULL;
}
router->servers[nservers]->backend_server = sref->server;
router->servers[nservers]->backend_conn_count = 0;
router->servers[nservers]->be_valid = false;
router->servers[nservers]->weight = 1000;
#if defined(SS_DEBUG)
router->servers[nservers]->be_chk_top = CHK_NUM_BACKEND;
router->servers[nservers]->be_chk_tail = CHK_NUM_BACKEND;
#endif
nservers += 1;
sref = sref->next;
}
router->servers[nservers] = NULL;
/*
* Until we know otherwise assume we have some available slaves.
*/
router->available_slaves = true;
/*
* If server weighting has been defined calculate the percentage
* of load that will be sent to each server. This is only used for
* calculating the least connections, either globally or within a
* service, or the number of current operations on a server.
*/
if ((weightby = serviceGetWeightingParameter(service)) != NULL)
{
int total = 0;
for (int n = 0; router->servers[n]; n++)
{
BACKEND *backend = router->servers[n];
char *param = serverGetParameter(backend->backend_server, weightby);
if (param)
{
total += atoi(param);
}
}
if (total == 0)
{
MXS_WARNING("Weighting Parameter for service '%s' "
"will be ignored as no servers have values "
"for the parameter '%s'.",
service->name, weightby);
}
else if (total < 0)
{
MXS_ERROR("Sum of weighting parameter '%s' for service '%s' exceeds "
"maximum value of %d. Weighting will be ignored.",
weightby, service->name, INT_MAX);
}
else
{
for (int n = 0; router->servers[n]; n++)
{
BACKEND *backend = router->servers[n];
char *param = serverGetParameter(backend->backend_server, weightby);
if (param)
{
int wght = atoi(param);
int perc = (wght * 1000) / total;
if (perc == 0)
{
perc = 1;
MXS_ERROR("Weighting parameter '%s' with a value of %d for"
" server '%s' rounds down to zero with total weight"
" of %d for service '%s'. No queries will be "
"routed to this server.", weightby, wght,
backend->backend_server->unique_name, total,
service->name);
}
else if (perc < 0)
{
MXS_ERROR("Weighting parameter '%s' for server '%s' is too large, "
"maximum value is %d. No weighting will be used for this server.",
weightby, backend->backend_server->unique_name, INT_MAX / 1000);
perc = 1000;
}
backend->weight = perc;
}
else
{
MXS_WARNING("Server '%s' has no parameter '%s' used for weighting"
" for service '%s'.", backend->backend_server->unique_name,
weightby, service->name);
}
}
}
}
/**
* vraa : is this necessary for readwritesplit ?
* Option : where can a read go?
* - master (only)
* - slave (only)
* - joined (to both)
*
* Process the options
*/
router->bitmask = 0;
router->bitvalue = 0;
/** Call this before refreshInstance */
if (options)
{
rwsplit_process_router_options(router, options);
}
/** These options cancel each other out */
if(router->rwsplit_config.rw_disable_sescmd_hist && router->rwsplit_config.rw_max_sescmd_history_size > 0)
{
router->rwsplit_config.rw_max_sescmd_history_size = 0;
}
/**
* Set default value for max_slave_connections as 100%. This way
* LEAST_CURRENT_OPERATIONS allows us to balance evenly across all the
* configured slaves.
*/
router->rwsplit_config.rw_max_slave_conn_count = nservers;
if (router->rwsplit_config.rw_slave_select_criteria == UNDEFINED_CRITERIA)
{
router->rwsplit_config.rw_slave_select_criteria = DEFAULT_CRITERIA;
}
/**
* Copy all config parameters from service to router instance.
* Finally, copy version number to indicate that configs match.
*/
param = config_get_param(service->svc_config_param, "max_slave_connections");
if (param != NULL)
{
refreshInstance(router, param);
}
/**
* Read default value for slave replication lag upper limit and then
* configured value if it exists.
*/
router->rwsplit_config.rw_max_slave_replication_lag = CONFIG_MAX_SLAVE_RLAG;
param = config_get_param(service->svc_config_param, "max_slave_replication_lag");
if (param != NULL)
{
refreshInstance(router, param);
}
router->rwsplit_version = service->svc_config_version;
/** Set default values */
router->rwsplit_config.rw_use_sql_variables_in = CONFIG_SQL_VARIABLES_IN;
param = config_get_param(service->svc_config_param, "use_sql_variables_in");
if (param != NULL)
{
refreshInstance(router, param);
}
/**
* We have completed the creation of the router data, so now
* insert this router into the linked list of routers
* that have been created with this module.
*/
spinlock_acquire(&instlock);
router->next = instances;
instances = router;
spinlock_release(&instlock);
return (ROUTER *)router;
}
/**
* Associate a new session with this instance of the router.
*
* The session is used to store all the data required for a particular
* client connection.
*
* @param instance The router instance data
* @param session The session itself
* @return Session specific data for this session
*/
static void* newSession(
ROUTER* router_inst,
SESSION* session)
{
backend_ref_t* backend_ref; /*< array of backend references (DCB,BACKEND,cursor) */
backend_ref_t* master_ref = NULL; /*< pointer to selected master */
ROUTER_CLIENT_SES* client_rses = NULL;
ROUTER_INSTANCE* router = (ROUTER_INSTANCE *)router_inst;
bool succp;
int router_nservers = 0; /*< # of servers in total */
int max_nslaves; /*< max # of slaves used in this session */
int max_slave_rlag; /*< max allowed replication lag for any slave */
int i;
const int min_nservers = 1; /*< hard-coded for now */
client_rses = (ROUTER_CLIENT_SES *)calloc(1, sizeof(ROUTER_CLIENT_SES));
if (client_rses == NULL)
{
ss_dassert(false);
goto return_rses;
}
#if defined(SS_DEBUG)
client_rses->rses_chk_top = CHK_NUM_ROUTER_SES;
client_rses->rses_chk_tail = CHK_NUM_ROUTER_SES;
#endif
client_rses->router = router;
client_rses->client_dcb = session->client;
/**
* If service config has been changed, reload config from service to
* router instance first.
*/
spinlock_acquire(&router->lock);
if (router->service->svc_config_version > router->rwsplit_version)
{
/** re-read all parameters to rwsplit config structure */
refreshInstance(router, NULL); /*< scan through all parameters */
/** increment rwsplit router's config version number */
router->rwsplit_version = router->service->svc_config_version;
/** Read options */
rwsplit_process_router_options(router, router->service->routerOptions);
}
/** Copy config struct from router instance */
memcpy(&client_rses->rses_config,&router->rwsplit_config,sizeof(rwsplit_config_t));
spinlock_release(&router->lock);
/**
* Set defaults to session variables.
*/
client_rses->rses_autocommit_enabled = true;
client_rses->rses_transaction_active = false;
router_nservers = router_get_servercount(router);
if (!have_enough_servers(&client_rses,
min_nservers,
router_nservers,
router))
{
goto return_rses;
}
/**
* Create backend reference objects for this session.
*/
backend_ref = (backend_ref_t *)calloc(1, router_nservers*sizeof(backend_ref_t));
if (backend_ref == NULL)
{
/** log this */
free(client_rses);
free(backend_ref);
client_rses = NULL;
goto return_rses;
}
/**
* Initialize backend references with BACKEND ptr.
* Initialize session command cursors for each backend reference.
*/
for (i=0; i< router_nservers; i++)
{
#if defined(SS_DEBUG)
backend_ref[i].bref_chk_top = CHK_NUM_BACKEND_REF;
backend_ref[i].bref_chk_tail = CHK_NUM_BACKEND_REF;
backend_ref[i].bref_sescmd_cur.scmd_cur_chk_top = CHK_NUM_SESCMD_CUR;
backend_ref[i].bref_sescmd_cur.scmd_cur_chk_tail = CHK_NUM_SESCMD_CUR;
#endif
backend_ref[i].bref_state = 0;
backend_ref[i].bref_backend = router->servers[i];
/** store pointers to sescmd list to both cursors */
backend_ref[i].bref_sescmd_cur.scmd_cur_rses = client_rses;
backend_ref[i].bref_sescmd_cur.scmd_cur_active = false;
backend_ref[i].bref_sescmd_cur.scmd_cur_ptr_property =
&client_rses->rses_properties[RSES_PROP_TYPE_SESCMD];
backend_ref[i].bref_sescmd_cur.scmd_cur_cmd = NULL;
}
max_nslaves = rses_get_max_slavecount(client_rses, router_nservers);
max_slave_rlag = rses_get_max_replication_lag(client_rses);
spinlock_init(&client_rses->rses_lock);
client_rses->rses_backend_ref = backend_ref;
/**
* Find a backend servers to connect to.
* This command requires that rsession's lock is held.
*/
succp = rses_begin_locked_router_action(client_rses);
if(!succp)
{
free(client_rses->rses_backend_ref);
free(client_rses);
client_rses = NULL;
goto return_rses;
}
succp = select_connect_backend_servers(&master_ref,
backend_ref,
router_nservers,
max_nslaves,
max_slave_rlag,
client_rses->rses_config.rw_slave_select_criteria,
session,
router);
rses_end_locked_router_action(client_rses);
/**
* Master and at least <min_nslaves> slaves must be found
*/
if (!succp) {
free(client_rses->rses_backend_ref);
free(client_rses);
client_rses = NULL;
goto return_rses;
}
/** Copy backend pointers to router session. */
client_rses->rses_master_ref = master_ref;
/* assert with master_host */
ss_dassert(master_ref && (master_ref->bref_backend->backend_server && SERVER_MASTER));
client_rses->rses_backend_ref = backend_ref;
client_rses->rses_nbackends = router_nservers; /*< # of backend servers */
if(client_rses->rses_config.rw_max_slave_conn_percent)
{
int n_conn = 0;
double pct = (double)client_rses->rses_config.rw_max_slave_conn_percent / 100.0;
n_conn = MAX(floor((double)client_rses->rses_nbackends * pct),1);
client_rses->rses_config.rw_max_slave_conn_count = n_conn;
}
router->stats.n_sessions += 1;
/**
* Version is bigger than zero once initialized.
*/
atomic_add(&client_rses->rses_versno, 2);
ss_dassert(client_rses->rses_versno == 2);
/**
* Add this session to end of the list of active sessions in router.
*/
spinlock_acquire(&router->lock);
client_rses->next = router->connections;
router->connections = client_rses;
spinlock_release(&router->lock);
return_rses:
#if defined(SS_DEBUG)
if (client_rses != NULL)
{
CHK_CLIENT_RSES(client_rses);
}
#endif
return (void *)client_rses;
}
/**
* Close a session with the router, this is the mechanism
* by which a router may cleanup data structure etc.
*
* @param instance The router instance data
* @param session The session being closed
*/
static void closeSession(
ROUTER* instance,
void* router_session)
{
ROUTER_CLIENT_SES* router_cli_ses;
backend_ref_t* backend_ref;
MXS_DEBUG("%lu [RWSplit:closeSession]", pthread_self());
/**
* router session can be NULL if newSession failed and it is discarding
* its connections and DCB's.
*/
if (router_session == NULL)
{
return;
}
router_cli_ses = (ROUTER_CLIENT_SES *)router_session;
CHK_CLIENT_RSES(router_cli_ses);
backend_ref = router_cli_ses->rses_backend_ref;
/**
* Lock router client session for secure read and update.
*/
if (!router_cli_ses->rses_closed &&
rses_begin_locked_router_action(router_cli_ses))
{
int i;
/**
* This sets router closed. Nobody is allowed to use router
* without checking this first.
*/
router_cli_ses->rses_closed = true;
for (i=0; i<router_cli_ses->rses_nbackends; i++)
{
backend_ref_t* bref = &backend_ref[i];
DCB* dcb = bref->bref_dcb;
/** Close those which had been connected */
if (BREF_IS_IN_USE(bref))
{
CHK_DCB(dcb);
#if defined(SS_DEBUG)
/**
* session must be moved to SESSION_STATE_STOPPING state before
* router session is closed.
*/
if (dcb->session != NULL)
{
ss_dassert(dcb->session->state == SESSION_STATE_STOPPING);
}
#endif
/** Clean operation counter in bref and in SERVER */
while (BREF_IS_WAITING_RESULT(bref))
{
bref_clear_state(bref, BREF_WAITING_RESULT);
}
bref_clear_state(bref, BREF_IN_USE);
bref_set_state(bref, BREF_CLOSED);
/**
* closes protocol and dcb
*/
dcb_close(dcb);
/** decrease server current connection counters */
atomic_add(&bref->bref_backend->backend_conn_count, -1);
}
}
/** Unlock */
rses_end_locked_router_action(router_cli_ses);
}
}
/**
* When router session is closed, freeSession can be called to free allocated
* resources.
*
* @param router_instance The router instance the session belongs to
* @param router_client_session Client session
*
*/
static void freeSession(
ROUTER* router_instance,
void* router_client_session)
{
ROUTER_CLIENT_SES* router_cli_ses;
ROUTER_INSTANCE* router;
int i;
router_cli_ses = (ROUTER_CLIENT_SES *)router_client_session;
router = (ROUTER_INSTANCE *)router_instance;
spinlock_acquire(&router->lock);
if (router->connections == router_cli_ses) {
router->connections = router_cli_ses->next;
} else {
ROUTER_CLIENT_SES* ptr = router->connections;
while (ptr && ptr->next != router_cli_ses) {
ptr = ptr->next;
}
if (ptr) {
ptr->next = router_cli_ses->next;
}
}
spinlock_release(&router->lock);
/**
* For each property type, walk through the list, finalize properties
* and free the allocated memory.
*/
for (i=RSES_PROP_TYPE_FIRST; i<RSES_PROP_TYPE_COUNT; i++)
{
rses_property_t* p = router_cli_ses->rses_properties[i];
rses_property_t* q = p;
while (p != NULL)
{
q = p->rses_prop_next;
rses_property_done(p);
p = q;
}
}
/*
* We are no longer in the linked list, free
* all the memory and other resources associated
* to the client session.
*/
free(router_cli_ses->rses_backend_ref);
free(router_cli_ses);
return;
}
/**
* Provide the router with a pointer to a suitable backend dcb.
*
* Detect failures in server statuses and reselect backends if necessary.
* If name is specified, server name becomes primary selection criteria.
* Similarly, if max replication lag is specified, skip backends which lag too
* much.
*
* @param p_dcb Address of the pointer to the resulting DCB
* @param rses Pointer to router client session
* @param btype Backend type
* @param name Name of the backend which is primarily searched. May be NULL.
*
* @return True if proper DCB was found, false otherwise.
*/
static bool get_dcb(
DCB** p_dcb,
ROUTER_CLIENT_SES* rses,
backend_type_t btype,
char* name,
int max_rlag)
{
backend_ref_t* backend_ref;
backend_ref_t* master_bref;
int i;
bool succp = false;
BACKEND* master_host;
CHK_CLIENT_RSES(rses);
ss_dassert(p_dcb != NULL && *(p_dcb) == NULL);
if (p_dcb == NULL)
{
goto return_succp;
}
backend_ref = rses->rses_backend_ref;
/** get root master from available servers */
master_bref = get_root_master_bref(rses);
/**
* If master can't be found, session will be closed.
*/
if (master_bref == NULL)
{
goto return_succp;
}
#if defined(SS_DEBUG)
/** master_host is just for additional checking */
master_host = get_root_master(backend_ref, rses->rses_nbackends);
if (master_bref->bref_backend != master_host)
{
MXS_INFO("Master has changed.");
}
#endif
if (name != NULL) /*< Choose backend by name from a hint */
{
ss_dassert(btype != BE_MASTER); /*< Master dominates and no name should be passed with it */
for (i=0; i<rses->rses_nbackends; i++)
{
BACKEND* b = backend_ref[i].bref_backend;
/**
* To become chosen:
* backend must be in use, name must match,
* root master node must be found,
* backend's role must be either slave, relay
* server, or master.
*/
if (BREF_IS_IN_USE((&backend_ref[i])) &&
(strncasecmp(
name,
b->backend_server->unique_name,
PATH_MAX) == 0) &&
master_bref->bref_backend != NULL &&
(SERVER_IS_SLAVE(b->backend_server) ||
SERVER_IS_RELAY_SERVER(b->backend_server) ||
SERVER_IS_MASTER(b->backend_server)))
{
*p_dcb = backend_ref[i].bref_dcb;
succp = true;
ss_dassert(backend_ref[i].bref_dcb->state != DCB_STATE_ZOMBIE);
break;
}
}
if (succp)
{
goto return_succp;
}
else
{
btype = BE_SLAVE;
}
}
if (btype == BE_SLAVE)
{
backend_ref_t* candidate_bref = NULL;
for (i=0; i<rses->rses_nbackends; i++)
{
BACKEND* b = (&backend_ref[i])->bref_backend;
/**
* Unused backend or backend which is not master nor
* slave can't be used
*/
if (!BREF_IS_IN_USE(&backend_ref[i]) ||
(!SERVER_IS_MASTER(b->backend_server) &&
!SERVER_IS_SLAVE(b->backend_server)))
{
continue;
}
/**
* If there are no candidates yet accept both master or
* slave.
*/
else if (candidate_bref == NULL)
{
/**
* Ensure that master has not changed dunring
* session and abort if it has.
*/
if (SERVER_IS_MASTER(b->backend_server) &&
&backend_ref[i] == master_bref)
{
/** found master */
candidate_bref = &backend_ref[i];
succp = true;
}
/**
* Ensure that max replication lag is not set
* or that candidate's lag doesn't exceed the
* maximum allowed replication lag.
*/
else if (max_rlag == MAX_RLAG_UNDEFINED ||
(b->backend_server->rlag != MAX_RLAG_NOT_AVAILABLE &&
b->backend_server->rlag <= max_rlag))
{
/** found slave */
candidate_bref = &backend_ref[i];
succp = true;
}
}
/**
* If candidate is master, any slave which doesn't break
* replication lag limits replaces it.
*/
else if (SERVER_IS_MASTER(candidate_bref->bref_backend->backend_server) &&
SERVER_IS_SLAVE(b->backend_server) &&
(max_rlag == MAX_RLAG_UNDEFINED ||
(b->backend_server->rlag != MAX_RLAG_NOT_AVAILABLE &&
b->backend_server->rlag <= max_rlag)) &&
!rses->rses_config.rw_master_reads)
{
/** found slave */
candidate_bref = &backend_ref[i];
succp = true;
}
/**
* When candidate exists, compare it against the current
* backend and update assign it to new candidate if
* necessary.
*/
else if (SERVER_IS_SLAVE(b->backend_server))
{
if (max_rlag == MAX_RLAG_UNDEFINED ||
(b->backend_server->rlag != MAX_RLAG_NOT_AVAILABLE &&
b->backend_server->rlag <= max_rlag))
{
candidate_bref = check_candidate_bref(
candidate_bref,
&backend_ref[i],
rses->rses_config.rw_slave_select_criteria);
}
else
{
MXS_INFO("Server %s:%d is too much behind the "
"master, %d s. and can't be chosen.",
b->backend_server->name,
b->backend_server->port,
b->backend_server->rlag);
}
}
} /*< for */
/** Assign selected DCB's pointer value */
if (candidate_bref != NULL)
{
*p_dcb = candidate_bref->bref_dcb;
}
goto return_succp;
} /*< if (btype == BE_SLAVE) */
/**
* If target was originally master only then the execution jumps
* directly here.
*/
if (btype == BE_MASTER)
{
if (BREF_IS_IN_USE(master_bref) &&
SERVER_IS_MASTER(master_bref->bref_backend->backend_server))
{
*p_dcb = master_bref->bref_dcb;
succp = true;
/** if bref is in use DCB should not be closed */
ss_dassert(master_bref->bref_dcb->state != DCB_STATE_ZOMBIE);
}
else
{
MXS_ERROR("Server at %s:%d should be master but "
"is %s instead and can't be chosen to master.",
master_bref->bref_backend->backend_server->name,
master_bref->bref_backend->backend_server->port,
STRSRVSTATUS(master_bref->bref_backend->backend_server));
succp = false;
}
}
return_succp:
return succp;
}
/**
* Find out which of the two backend servers has smaller value for select
* criteria property.
*
* @param cand previously selected candidate
* @param new challenger
* @param sc select criteria
*
* @return pointer to backend reference of that backend server which has smaller
* value in selection criteria. If either reference pointer is NULL then the
* other reference pointer value is returned.
*/
static backend_ref_t* check_candidate_bref(
backend_ref_t* cand,
backend_ref_t* new,
select_criteria_t sc)
{
int (*p)(const void *, const void *);
/** get compare function */
p = criteria_cmpfun[sc];
if (new == NULL)
{
return cand;
}
else if (cand == NULL || (p((void *)cand,(void *)new) > 0))
{
return new;
}
else
{
return cand;
}
}
/**
* Examine the query type, transaction state and routing hints. Find out the
* target for query routing.
*
* @param qtype Type of query
* @param trx_active Is transacation active or not
* @param hint Pointer to list of hints attached to the query buffer
*
* @return bitfield including the routing target, or the target server name
* if the query would otherwise be routed to slave.
*/
static route_target_t get_route_target (
skygw_query_type_t qtype,
bool trx_active,
bool load_active,
target_t use_sql_variables_in,
HINT* hint)
{
route_target_t target = TARGET_UNDEFINED;
/**
* These queries are not affected by hints
*/
if (!load_active && (QUERY_IS_TYPE(qtype, QUERY_TYPE_SESSION_WRITE) ||
/** Configured to allow writing variables to all nodes */
(use_sql_variables_in == TYPE_ALL &&
QUERY_IS_TYPE(qtype, QUERY_TYPE_GSYSVAR_WRITE)) ||
/** enable or disable autocommit are always routed to all */
QUERY_IS_TYPE(qtype, QUERY_TYPE_ENABLE_AUTOCOMMIT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_DISABLE_AUTOCOMMIT)))
{
/**
* This is problematic query because it would be routed to all
* backends but since this is SELECT that is not possible:
* 1. response set is not handled correctly in clientReply and
* 2. multiple results can degrade performance.
*
* Prepared statements are an exception to this since they do not
* actually do anything but only prepare the statement to be used.
* They can be safely routed to all backends since the execution
* is done later.
*
* With prepared statement caching the task of routing
* the execution of the prepared statements to the right server would be
* an easy one. Currently this is not supported.
*/
if (QUERY_IS_TYPE(qtype, QUERY_TYPE_READ) &&
!( QUERY_IS_TYPE(qtype, QUERY_TYPE_PREPARE_STMT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_PREPARE_NAMED_STMT)))
{
MXS_WARNING("The query can't be routed to all "
"backend servers because it includes SELECT and "
"SQL variable modifications which is not supported. "
"Set use_sql_variables_in=master or split the "
"query to two, where SQL variable modifications "
"are done in the first and the SELECT in the "
"second one.");
target = TARGET_MASTER;
}
target |= TARGET_ALL;
}
/**
* Hints may affect on routing of the following queries
*/
else if (!trx_active && !load_active &&
(QUERY_IS_TYPE(qtype, QUERY_TYPE_READ) || /*< any SELECT */
QUERY_IS_TYPE(qtype, QUERY_TYPE_SHOW_TABLES) || /*< 'SHOW TABLES' */
QUERY_IS_TYPE(qtype, QUERY_TYPE_USERVAR_READ)|| /*< read user var */
QUERY_IS_TYPE(qtype, QUERY_TYPE_SYSVAR_READ) || /*< read sys var */
QUERY_IS_TYPE(qtype, QUERY_TYPE_EXEC_STMT) || /*< prepared stmt exec */
QUERY_IS_TYPE(qtype, QUERY_TYPE_PREPARE_STMT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_PREPARE_NAMED_STMT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_GSYSVAR_READ))) /*< read global sys var */
{
/** First set expected targets before evaluating hints */
if (!QUERY_IS_TYPE(qtype, QUERY_TYPE_MASTER_READ) &&
(QUERY_IS_TYPE(qtype, QUERY_TYPE_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_SHOW_TABLES) || /*< 'SHOW TABLES' */
/** Configured to allow reading variables from slaves */
(use_sql_variables_in == TYPE_ALL &&
(QUERY_IS_TYPE(qtype, QUERY_TYPE_USERVAR_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_SYSVAR_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_GSYSVAR_READ)))))
{
target = TARGET_SLAVE;
}
if (QUERY_IS_TYPE(qtype, QUERY_TYPE_MASTER_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_EXEC_STMT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_PREPARE_STMT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_PREPARE_NAMED_STMT) ||
/** Configured not to allow reading variables from slaves */
(use_sql_variables_in == TYPE_MASTER &&
(QUERY_IS_TYPE(qtype, QUERY_TYPE_USERVAR_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_SYSVAR_READ))))
{
target = TARGET_MASTER;
}
/** process routing hints */
while (hint != NULL)
{
if (hint->type == HINT_ROUTE_TO_MASTER)
{
target = TARGET_MASTER; /*< override */
MXS_DEBUG("%lu [get_route_target] Hint: route to master.",
pthread_self());
break;
}
else if (hint->type == HINT_ROUTE_TO_NAMED_SERVER)
{
/**
* Searching for a named server. If it can't be
* found, the oroginal target is chosen.
*/
target |= TARGET_NAMED_SERVER;
MXS_DEBUG("%lu [get_route_target] Hint: route to "
"named server : ",
pthread_self());
}
else if (hint->type == HINT_ROUTE_TO_UPTODATE_SERVER)
{
/** not implemented */
}
else if (hint->type == HINT_ROUTE_TO_ALL)
{
/** not implemented */
}
else if (hint->type == HINT_PARAMETER)
{
if (strncasecmp(
(char *)hint->data,
"max_slave_replication_lag",
strlen("max_slave_replication_lag")) == 0)
{
target |= TARGET_RLAG_MAX;
}
else
{
MXS_ERROR("Unknown hint parameter "
"'%s' when 'max_slave_replication_lag' "
"was expected.",
(char *)hint->data);
}
}
else if (hint->type == HINT_ROUTE_TO_SLAVE)
{
target = TARGET_SLAVE;
MXS_DEBUG("%lu [get_route_target] Hint: route to "
"slave.",
pthread_self());
}
hint = hint->next;
} /*< while (hint != NULL) */
/** If nothing matches then choose the master */
if ((target & (TARGET_ALL|TARGET_SLAVE|TARGET_MASTER)) == 0)
{
target = TARGET_MASTER;
}
}
else
{
/** hints don't affect on routing */
ss_dassert(trx_active ||
(QUERY_IS_TYPE(qtype, QUERY_TYPE_WRITE) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_MASTER_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_SESSION_WRITE) ||
(QUERY_IS_TYPE(qtype, QUERY_TYPE_USERVAR_READ) &&
use_sql_variables_in == TYPE_MASTER) ||
(QUERY_IS_TYPE(qtype, QUERY_TYPE_SYSVAR_READ) &&
use_sql_variables_in == TYPE_MASTER) ||
(QUERY_IS_TYPE(qtype, QUERY_TYPE_GSYSVAR_READ) &&
use_sql_variables_in == TYPE_MASTER) ||
(QUERY_IS_TYPE(qtype, QUERY_TYPE_GSYSVAR_WRITE) &&
use_sql_variables_in == TYPE_MASTER) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_BEGIN_TRX) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_ENABLE_AUTOCOMMIT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_DISABLE_AUTOCOMMIT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_ROLLBACK) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_COMMIT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_EXEC_STMT) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_CREATE_TMP_TABLE) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_READ_TMP_TABLE) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_UNKNOWN)));
target = TARGET_MASTER;
}
#if defined(SS_EXTRA_DEBUG)
MXS_INFO("Selected target \"%s\"", STRTARGET(target));
#endif
return target;
}
/**
* Check if the query is a DROP TABLE... query and
* if it targets a temporary table, remove it from the hashtable.
* @param router_cli_ses Router client session
* @param querybuf GWBUF containing the query
* @param type The type of the query resolved so far
*/
void check_drop_tmp_table(
ROUTER_CLIENT_SES* router_cli_ses,
GWBUF* querybuf,
skygw_query_type_t type)
{
int tsize = 0, klen = 0,i;
char** tbl = NULL;
char *hkey,*dbname;
MYSQL_session* data;
DCB* master_dcb = NULL;
rses_property_t* rses_prop_tmp;
if(router_cli_ses == NULL || querybuf == NULL)
{
MXS_ERROR("[%s] Error: NULL parameters passed: %p %p",
__FUNCTION__,router_cli_ses,querybuf);
return;
}
if(router_cli_ses->rses_master_ref == NULL)
{
MXS_ERROR("[%s] Error: Master server reference is NULL.",
__FUNCTION__);
return;
}
rses_prop_tmp = router_cli_ses->rses_properties[RSES_PROP_TYPE_TMPTABLES];
master_dcb = router_cli_ses->rses_master_ref->bref_dcb;
if(master_dcb == NULL || master_dcb->session == NULL)
{
MXS_ERROR("[%s] Error: Master server DBC is NULL. "
"This means that the connection to the master server is already "
"closed while a query is still being routed.",__FUNCTION__);
return;
}
CHK_DCB(master_dcb);
data = (MYSQL_session*)master_dcb->session->data;
if(data == NULL)
{
MXS_ERROR("[%s] Error: User data in master server DBC is NULL.",__FUNCTION__);
return;
}
dbname = (char*)data->db;
if (is_drop_table_query(querybuf))
{
tbl = skygw_get_table_names(querybuf,&tsize,false);
if(tbl != NULL){
for(i = 0; i<tsize; i++)
{
klen = strlen(dbname) + strlen(tbl[i]) + 2;
hkey = calloc(klen,sizeof(char));
strcpy(hkey,dbname);
strcat(hkey,".");
strcat(hkey,tbl[i]);
if (rses_prop_tmp &&
rses_prop_tmp->rses_prop_data.temp_tables)
{
if (hashtable_delete(rses_prop_tmp->rses_prop_data.temp_tables,
(void *)hkey))
{
MXS_INFO("Temporary table dropped: %s",hkey);
}
}
free(tbl[i]);
free(hkey);
}
free(tbl);
}
}
}
/**
* Check if the query targets a temporary table.
* @param router_cli_ses Router client session
* @param querybuf GWBUF containing the query
* @param type The type of the query resolved so far
* @return The type of the query
*/
static skygw_query_type_t is_read_tmp_table(
ROUTER_CLIENT_SES* router_cli_ses,
GWBUF* querybuf,
skygw_query_type_t type)
{
bool target_tmp_table = false;
int tsize = 0, klen = 0,i;
char** tbl = NULL;
char *dbname;
char hkey[MYSQL_DATABASE_MAXLEN+MYSQL_TABLE_MAXLEN+2];
MYSQL_session* data;
DCB* master_dcb = NULL;
skygw_query_type_t qtype = type;
rses_property_t* rses_prop_tmp;
if(router_cli_ses == NULL || querybuf == NULL)
{
MXS_ERROR("[%s] Error: NULL parameters passed: %p %p",
__FUNCTION__,router_cli_ses,querybuf);
return type;
}
if(router_cli_ses->rses_master_ref == NULL)
{
MXS_ERROR("[%s] Error: Master server reference is NULL.",
__FUNCTION__);
return type;
}
rses_prop_tmp = router_cli_ses->rses_properties[RSES_PROP_TYPE_TMPTABLES];
master_dcb = router_cli_ses->rses_master_ref->bref_dcb;
if(master_dcb == NULL || master_dcb->session == NULL)
{
MXS_ERROR("[%s] Error: Master server DBC is NULL. "
"This means that the connection to the master server is already "
"closed while a query is still being routed.",__FUNCTION__);
return qtype;
}
CHK_DCB(master_dcb);
data = (MYSQL_session*)master_dcb->session->data;
if(data == NULL)
{
MXS_ERROR("[%s] Error: User data in master server DBC is NULL.",__FUNCTION__);
return qtype;
}
dbname = (char*)data->db;
if (QUERY_IS_TYPE(qtype, QUERY_TYPE_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_LOCAL_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_USERVAR_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_SYSVAR_READ) ||
QUERY_IS_TYPE(qtype, QUERY_TYPE_GSYSVAR_READ))
{
tbl = skygw_get_table_names(querybuf,&tsize,false);
if (tbl != NULL && tsize > 0)
{
/** Query targets at least one table */
for(i = 0; i<tsize && !target_tmp_table && tbl[i]; i++)
{
sprintf(hkey,"%s.%s",dbname,tbl[i]);
if (rses_prop_tmp &&
rses_prop_tmp->rses_prop_data.temp_tables)
{
if( (target_tmp_table =
(bool)hashtable_fetch(rses_prop_tmp->rses_prop_data.temp_tables,(void *)hkey)))
{
/**Query target is a temporary table*/
qtype = QUERY_TYPE_READ_TMP_TABLE;
MXS_INFO("Query targets a temporary table: %s",hkey);
}
}
}
}
}
if(tbl != NULL){
for(i = 0; i<tsize;i++)
{
free(tbl[i]);
}
free(tbl);
}
return qtype;
}
/**
* If query is of type QUERY_TYPE_CREATE_TMP_TABLE then find out
* the database and table name, create a hashvalue and
* add it to the router client session's property. If property
* doesn't exist then create it first.
* @param router_cli_ses Router client session
* @param querybuf GWBUF containing the query
* @param type The type of the query resolved so far
*/
static void check_create_tmp_table(
ROUTER_CLIENT_SES* router_cli_ses,
GWBUF* querybuf,
skygw_query_type_t type)
{
int klen = 0;
char *hkey,*dbname;
MYSQL_session* data;
DCB* master_dcb = NULL;
rses_property_t* rses_prop_tmp;
HASHTABLE* h;
if(router_cli_ses == NULL || querybuf == NULL)
{
MXS_ERROR("[%s] Error: NULL parameters passed: %p %p",
__FUNCTION__,router_cli_ses,querybuf);
return;
}
if(router_cli_ses->rses_master_ref == NULL)
{
MXS_ERROR("[%s] Error: Master server reference is NULL.",
__FUNCTION__);
return;
}
rses_prop_tmp = router_cli_ses->rses_properties[RSES_PROP_TYPE_TMPTABLES];
master_dcb = router_cli_ses->rses_master_ref->bref_dcb;
if(master_dcb == NULL || master_dcb->session == NULL)
{
MXS_ERROR("[%s] Error: Master server DCB is NULL. "
"This means that the connection to the master server is already "
"closed while a query is still being routed.",__FUNCTION__);
return;
}
CHK_DCB(master_dcb);
data = (MYSQL_session*)master_dcb->session->data;
if(data == NULL)
{
MXS_ERROR("[%s] Error: User data in master server DBC is NULL.",__FUNCTION__);
return;
}
dbname = (char*)data->db;
if (QUERY_IS_TYPE(type, QUERY_TYPE_CREATE_TMP_TABLE))
{
bool is_temp = true;
char* tblname = NULL;
tblname = skygw_get_created_table_name(querybuf);
if (tblname && strlen(tblname) > 0)
{
klen = strlen(dbname) + strlen(tblname) + 2;
hkey = calloc(klen,sizeof(char));
strcpy(hkey,dbname);
strcat(hkey,".");
strcat(hkey,tblname);
}
else
{
hkey = NULL;
}
if(rses_prop_tmp == NULL)
{
if((rses_prop_tmp =
(rses_property_t*)calloc(1,sizeof(rses_property_t))))
{
#if defined(SS_DEBUG)
rses_prop_tmp->rses_prop_chk_top = CHK_NUM_ROUTER_PROPERTY;
rses_prop_tmp->rses_prop_chk_tail = CHK_NUM_ROUTER_PROPERTY;
#endif
rses_prop_tmp->rses_prop_rsession = router_cli_ses;
rses_prop_tmp->rses_prop_refcount = 1;
rses_prop_tmp->rses_prop_next = NULL;
rses_prop_tmp->rses_prop_type = RSES_PROP_TYPE_TMPTABLES;
router_cli_ses->rses_properties[RSES_PROP_TYPE_TMPTABLES] = rses_prop_tmp;
}
else
{
MXS_ERROR("Call to malloc() failed.");
}
}
if(rses_prop_tmp){
if (rses_prop_tmp->rses_prop_data.temp_tables == NULL)
{
h = hashtable_alloc(7, hashkeyfun, hashcmpfun);
hashtable_memory_fns(h,hstrdup,NULL,hfree,NULL);
if (h != NULL)
{
rses_prop_tmp->rses_prop_data.temp_tables = h;
}else{
MXS_ERROR("Failed to allocate a new hashtable.");
}
}
if (hkey && rses_prop_tmp->rses_prop_data.temp_tables &&
hashtable_add(rses_prop_tmp->rses_prop_data.temp_tables,
(void *)hkey,
(void *)is_temp) == 0) /*< Conflict in hash table */
{
MXS_INFO("Temporary table conflict in hashtable: %s", hkey);
}
#if defined(SS_DEBUG)
{
bool retkey =
hashtable_fetch(
rses_prop_tmp->rses_prop_data.temp_tables,
hkey);
if (retkey)
{
MXS_INFO("Temporary table added: %s", hkey);
}
}
#endif
}
free(hkey);
free(tblname);
}
}
/**
* Get client DCB pointer of the router client session.
* This routine must be protected by Router client session lock.
*
* @param rses Router client session pointer
*
* @return Pointer to client DCB
*/
static DCB* rses_get_client_dcb(
ROUTER_CLIENT_SES* rses)
{
DCB* dcb = NULL;
int i;
for (i=0; i<rses->rses_nbackends; i++)
{
if ((dcb = rses->rses_backend_ref[i].bref_dcb) != NULL &&
BREF_IS_IN_USE(&rses->rses_backend_ref[i]) &&
dcb->session != NULL &&
dcb->session->client != NULL)
{
return dcb->session->client;
}
}
return NULL;
}
/**
* The main routing entry, this is called with every packet that is
* received and has to be forwarded to the backend database.
*
* The routeQuery will make the routing decision based on the contents
* of the instance, session and the query itself in the queue. The
* data in the queue may not represent a complete query, it represents
* the data that has been received. The query router itself is responsible
* for buffering the partial query, a later call to the query router will
* contain the remainder, or part thereof of the query.
*
* @param instance The query router instance
* @param router_session The session associated with the client
* @param querybuf MaxScale buffer queue with received packet
*
* @return if succeed 1, otherwise 0
* If routeQuery fails, it means that router session has failed.
* In any tolerated failure, handleError is called and if necessary,
* an error message is sent to the client.
*
* For now, routeQuery don't tolerate errors, so any error will close
* the session. vraa 14.6.14
*/
static int routeQuery(
ROUTER* instance,
void* router_session,
GWBUF* querybuf)
{
int ret = 0;
ROUTER_INSTANCE* inst = (ROUTER_INSTANCE *)instance;
ROUTER_CLIENT_SES* router_cli_ses = (ROUTER_CLIENT_SES *)router_session;
bool succp = false;
CHK_CLIENT_RSES(router_cli_ses);
/**
* GWBUF is called "type undefined" when the incoming data isn't parsed
* and MySQL packets haven't been extracted to separate buffers.
* "Undefined" == "untyped".
* Untyped GWBUF means that it can consist of incomplete and/or multiple
* MySQL packets.
* Read and route found MySQL packets one by one and store potential
* incomplete packet to DCB's dcb_readqueue.
*/
if (GWBUF_IS_TYPE_UNDEFINED(querybuf))
{
GWBUF* tmpbuf = querybuf;
do
{
/**
* Try to read complete MySQL packet from tmpbuf.
* Append leftover to client's read queue.
*/
if ((querybuf = modutil_get_next_MySQL_packet(&tmpbuf)) == NULL)
{
if (GWBUF_LENGTH(tmpbuf) > 0)
{
DCB* dcb = rses_get_client_dcb(router_cli_ses);
dcb->dcb_readqueue = gwbuf_append(dcb->dcb_readqueue, tmpbuf);
}
succp = true;
goto retblock;
}
/** Mark buffer to as MySQL type */
gwbuf_set_type(querybuf, GWBUF_TYPE_MYSQL);
gwbuf_set_type(querybuf, GWBUF_TYPE_SINGLE_STMT);
/**
* If router is closed, discard the packet
*/
if (router_cli_ses->rses_closed)
{
uint8_t* packet;
mysql_server_cmd_t packet_type;
packet = GWBUF_DATA(querybuf);
packet_type = packet[4];
if (packet_type != MYSQL_COM_QUIT)
{
char* query_str = modutil_get_query(querybuf);
MXS_ERROR("Can't route %s:\"%s\" to "
"backend server. Router is closed.",
STRPACKETTYPE(packet_type),
(query_str == NULL ? "(empty)" : query_str));
free(query_str);
}
}
else
{
/** route_single_stmt expects the buffer to be contiguous. */
querybuf = gwbuf_make_contiguous(querybuf);
succp = route_single_stmt(inst, router_cli_ses, querybuf);
}
}
while (tmpbuf != NULL);
}
/**
* If router is closed, discard the packet
*/
else if (router_cli_ses->rses_closed)
{
uint8_t* packet;
mysql_server_cmd_t packet_type;
packet = GWBUF_DATA(querybuf);
packet_type = packet[4];
if (packet_type != MYSQL_COM_QUIT)
{
char* query_str = modutil_get_query(querybuf);
MXS_ERROR("Can't route %s:\"%s\" to "
"backend server. Router is closed.",
STRPACKETTYPE(packet_type),
(query_str == NULL ? "(empty)" : query_str));
free(query_str);
}
}
else
{
/** route_single_stmt expects the buffer to be contiguous. */
querybuf = gwbuf_make_contiguous(querybuf);
succp = route_single_stmt(inst, router_cli_ses, querybuf);
}
retblock:
#if defined(SS_DEBUG2)
if (querybuf != NULL)
{
char* canonical_query_str;
canonical_query_str = skygw_get_canonical(querybuf);
if (canonical_query_str != NULL)
{
MXS_INFO("Canonical version: %s", canonical_query_str);
free(canonical_query_str);
}
}
#endif
if (querybuf != NULL) gwbuf_free(querybuf);
if (succp) ret = 1;
return ret;
}
/**
* Routing function. Find out query type, backend type, and target DCB(s).
* Then route query to found target(s).
* @param inst router instance
* @param rses router session
* @param querybuf GWBUF including the query
*
* @return true if routing succeed or if it failed due to unsupported query.
* false if backend failure was encountered.
*/
static bool route_single_stmt(
ROUTER_INSTANCE* inst,
ROUTER_CLIENT_SES* rses,
GWBUF* querybuf)
{
skygw_query_type_t qtype = QUERY_TYPE_UNKNOWN;
mysql_server_cmd_t packet_type = MYSQL_COM_UNDEFINED;
uint8_t* packet;
size_t packet_len;
int ret = 0;
DCB* master_dcb = NULL;
DCB* target_dcb = NULL;
route_target_t route_target;
bool succp = false;
int rlag_max = MAX_RLAG_UNDEFINED;
backend_type_t btype; /*< target backend type */
ss_dassert(querybuf->next == NULL); // The buffer must be contiguous.
ss_dassert(!GWBUF_IS_TYPE_UNDEFINED(querybuf));
/**
* Read stored master DCB pointer. If master is not set, routing must
* be aborted
*/
if ((master_dcb = rses->rses_master_ref->bref_dcb) == NULL)
{
char* query_str = modutil_get_query(querybuf);
CHK_DCB(master_dcb);
MXS_ERROR("Can't route %s:%s:\"%s\" to "
"backend server. Session doesn't have a Master "
"node",
STRPACKETTYPE(packet_type),
STRQTYPE(qtype),
(query_str == NULL ? "(empty)" : query_str));
free(query_str);
succp = false;
goto retblock;
}
packet = GWBUF_DATA(querybuf);
packet_len = gw_mysql_get_byte3(packet);
if(packet_len == 0)
{
/** Empty packet signals end of LOAD DATA LOCAL INFILE, send it to master*/
route_target = TARGET_MASTER;
packet_type = MYSQL_COM_UNDEFINED;
rses->rses_load_active = false;
route_target = TARGET_MASTER;
MXS_INFO("> LOAD DATA LOCAL INFILE finished: "
"%lu bytes sent.", rses->rses_load_data_sent + gwbuf_length(querybuf));
}
else
{
packet_type = packet[4];
switch(packet_type) {
case MYSQL_COM_QUIT: /*< 1 QUIT will close all sessions */
case MYSQL_COM_INIT_DB: /*< 2 DDL must go to the master */
case MYSQL_COM_REFRESH: /*< 7 - I guess this is session but not sure */
case MYSQL_COM_DEBUG: /*< 0d all servers dump debug info to stdout */
case MYSQL_COM_PING: /*< 0e all servers are pinged */
case MYSQL_COM_CHANGE_USER: /*< 11 all servers change it accordingly */
qtype = QUERY_TYPE_SESSION_WRITE;
break;
case MYSQL_COM_CREATE_DB: /**< 5 DDL must go to the master */
case MYSQL_COM_DROP_DB: /**< 6 DDL must go to the master */
case MYSQL_COM_STMT_CLOSE: /*< free prepared statement */
case MYSQL_COM_STMT_SEND_LONG_DATA: /*< send data to column */
case MYSQL_COM_STMT_RESET: /*< resets the data of a prepared statement */
qtype = QUERY_TYPE_WRITE;
break;
case MYSQL_COM_QUERY:
qtype = query_classifier_get_type(querybuf);
break;
case MYSQL_COM_STMT_PREPARE:
qtype = query_classifier_get_type(querybuf);
qtype |= QUERY_TYPE_PREPARE_STMT;
break;
case MYSQL_COM_STMT_EXECUTE:
/** Parsing is not needed for this type of packet */
qtype = QUERY_TYPE_EXEC_STMT;
break;
case MYSQL_COM_SHUTDOWN: /**< 8 where should shutdown be routed ? */
case MYSQL_COM_STATISTICS: /**< 9 ? */
case MYSQL_COM_PROCESS_INFO: /**< 0a ? */
case MYSQL_COM_CONNECT: /**< 0b ? */
case MYSQL_COM_PROCESS_KILL: /**< 0c ? */
case MYSQL_COM_TIME: /**< 0f should this be run in gateway ? */
case MYSQL_COM_DELAYED_INSERT: /**< 10 ? */
case MYSQL_COM_DAEMON: /**< 1d ? */
default:
break;
} /**< switch by packet type */
if (!rses_begin_locked_router_action(rses))
{
succp = false;
goto retblock;
}
/**
* Check if the query has anything to do with temporary tables.
*/
qtype = is_read_tmp_table(rses, querybuf, qtype);
check_create_tmp_table(rses, querybuf, qtype);
check_drop_tmp_table(rses, querybuf,qtype);
/**
* Check if this is a LOAD DATA LOCAL INFILE query. If so, send all queries
* to the master until the last, empty packet arrives.
*/
if (!rses->rses_load_active)
{
skygw_query_op_t queryop = query_classifier_get_operation(querybuf);
if (queryop == QUERY_OP_LOAD)
{
rses->rses_load_active = true;
rses->rses_load_data_sent = 0;
}
}
else
{
rses->rses_load_data_sent += gwbuf_length(querybuf);
}
rses_end_locked_router_action(rses);
/**
* If autocommit is disabled or transaction is explicitly started
* transaction becomes active and master gets all statements until
* transaction is committed and autocommit is enabled again.
*/
if (rses->rses_autocommit_enabled &&
QUERY_IS_TYPE(qtype, QUERY_TYPE_DISABLE_AUTOCOMMIT))
{
rses->rses_autocommit_enabled = false;
if (!rses->rses_transaction_active)
{
rses->rses_transaction_active = true;
}
}
else if (!rses->rses_transaction_active &&
QUERY_IS_TYPE(qtype, QUERY_TYPE_BEGIN_TRX))
{
rses->rses_transaction_active = true;
}
/**
* Explicit COMMIT and ROLLBACK, implicit COMMIT.
*/
if (rses->rses_autocommit_enabled &&
rses->rses_transaction_active &&
(QUERY_IS_TYPE(qtype,QUERY_TYPE_COMMIT) ||
QUERY_IS_TYPE(qtype,QUERY_TYPE_ROLLBACK)))
{
rses->rses_transaction_active = false;
}
else if (!rses->rses_autocommit_enabled &&
QUERY_IS_TYPE(qtype, QUERY_TYPE_ENABLE_AUTOCOMMIT))
{
rses->rses_autocommit_enabled = true;
rses->rses_transaction_active = false;
}
if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_INFO))
{
if (!rses->rses_load_active)
{
uint8_t* packet = GWBUF_DATA(querybuf);
unsigned char ptype = packet[4];
size_t len = MIN(GWBUF_LENGTH(querybuf),
MYSQL_GET_PACKET_LEN((unsigned char *)querybuf->start) - 1);
char* data = (char*) &packet[5];
char* contentstr = strndup(data, MIN(len, RWSPLIT_TRACE_MSG_LEN));
char* qtypestr = skygw_get_qtype_str(qtype);
MXS_INFO("> Autocommit: %s, trx is %s, cmd: %s, type: %s, "
"stmt: %s%s %s",
(rses->rses_autocommit_enabled ? "[enabled]" : "[disabled]"),
(rses->rses_transaction_active ? "[open]" : "[not open]"),
STRPACKETTYPE(ptype),
(qtypestr == NULL ? "N/A" : qtypestr),
contentstr,
(querybuf->hint == NULL ? "" : ", Hint:"),
(querybuf->hint == NULL ? "" : STRHINTTYPE(querybuf->hint->type)));
free(contentstr);
free(qtypestr);
}
else
{
MXS_INFO("> Processing LOAD DATA LOCAL INFILE: "
"%lu bytes sent.", rses->rses_load_data_sent);
}
}
/**
* Find out where to route the query. Result may not be clear; it is
* possible to have a hint for routing to a named server which can
* be either slave or master.
* If query would otherwise be routed to slave then the hint determines
* actual target server if it exists.
*
* route_target is a bitfield and may include :
* TARGET_ALL
* - route to all connected backend servers
* TARGET_SLAVE[|TARGET_NAMED_SERVER|TARGET_RLAG_MAX]
* - route primarily according to hints, then to slave and if those
* failed, eventually to master
* TARGET_MASTER[|TARGET_NAMED_SERVER|TARGET_RLAG_MAX]
* - route primarily according to the hints and if they failed,
* eventually to master
*/
route_target = get_route_target(qtype,
rses->rses_transaction_active,
rses->rses_load_active,
rses->rses_config.rw_use_sql_variables_in,
querybuf->hint);
if (TARGET_IS_ALL(route_target))
{
/** Multiple, conflicting routing target. Return error */
if (TARGET_IS_MASTER(route_target) ||
TARGET_IS_SLAVE(route_target))
{
backend_ref_t* bref = rses->rses_backend_ref;
char* query_str = modutil_get_query(querybuf);
char* qtype_str = skygw_get_qtype_str(qtype);
MXS_ERROR("Can't route %s:%s:\"%s\". SELECT with "
"session data modification is not supported "
"if configuration parameter "
"use_sql_variables_in=all .",
STRPACKETTYPE(packet_type),
qtype_str,
(query_str == NULL ? "(empty)" : query_str));
MXS_INFO("Unable to route the query "
"without losing session data "
"modification from other "
"servers. <");
while (bref != NULL && !BREF_IS_IN_USE(bref))
{
bref++;
}
if (bref != NULL && BREF_IS_IN_USE(bref))
{
/** Create and add MySQL error to eventqueue */
modutil_reply_parse_error(
bref->bref_dcb,
strdup("Routing query to backend failed. "
"See the error log for further "
"details."),
0);
succp = true;
}
else
{
/**
* If there were no available backend references
* available return false - session will be closed
*/
MXS_ERROR("Sending error message to client "
"failed. Router doesn't have any "
"available backends. Session will be "
"closed.");
succp = false;
}
if (query_str) free (query_str);
if (qtype_str) free(qtype_str);
goto retblock;
}
/**
* It is not sure if the session command in question requires
* response. Statement is examined in route_session_write.
* Router locking is done inside the function.
*/
succp = route_session_write(
rses,
gwbuf_clone(querybuf),
inst,
packet_type,
qtype);
if (succp)
{
atomic_add(&inst->stats.n_all, 1);
}
goto retblock;
}
}
/** Lock router session */
if (!rses_begin_locked_router_action(rses))
{
if (packet_type != MYSQL_COM_QUIT)
{
char* query_str = modutil_get_query(querybuf);
MXS_ERROR("Can't route %s:%s:\"%s\" to "
"backend server. Router is closed.",
STRPACKETTYPE(packet_type),
STRQTYPE(qtype),
(query_str == NULL ? "(empty)" : query_str));
free(query_str);
}
succp = false;
goto retblock;
}
/**
* There is a hint which either names the target backend or
* hint which sets maximum allowed replication lag for the
* backend.
*/
if (TARGET_IS_NAMED_SERVER(route_target) ||
TARGET_IS_RLAG_MAX(route_target))
{
HINT* hint;
char* named_server = NULL;
hint = querybuf->hint;
while (hint != NULL)
{
if (hint->type == HINT_ROUTE_TO_NAMED_SERVER)
{
/**
* Set the name of searched
* backend server.
*/
named_server = hint->data;
MXS_INFO("Hint: route to server "
"'%s'",
named_server);
}
else if (hint->type == HINT_PARAMETER &&
(strncasecmp((char *)hint->data,
"max_slave_replication_lag",
strlen("max_slave_replication_lag")) == 0))
{
int val = (int) strtol((char *)hint->value,
(char **)NULL, 10);
if (val != 0 || errno == 0)
{
/**
* Set max. acceptable
* replication lag
* value for backend srv
*/
rlag_max = val;
MXS_INFO("Hint: "
"max_slave_replication_lag=%d",
rlag_max);
}
}
hint = hint->next;
} /*< while */
if (rlag_max == MAX_RLAG_UNDEFINED) /*< no rlag max hint, use config */
{
rlag_max = rses_get_max_replication_lag(rses);
}
btype = route_target & TARGET_SLAVE ? BE_SLAVE : BE_MASTER; /*< target may be master or slave */
/**
* Search backend server by name or replication lag.
* If it fails, then try to find valid slave or master.
*/
succp = get_dcb(&target_dcb, rses, btype, named_server,rlag_max);
if (!succp)
{
if (TARGET_IS_NAMED_SERVER(route_target))
{
MXS_INFO("Was supposed to route to named server "
"%s but couldn't find the server in a "
"suitable state.",
named_server);
}
else if (TARGET_IS_RLAG_MAX(route_target))
{
MXS_INFO("Was supposed to route to server with "
"replication lag at most %d but couldn't "
"find such a slave.",
rlag_max);
}
}
}
else if (TARGET_IS_SLAVE(route_target))
{
btype = BE_SLAVE;
if (rlag_max == MAX_RLAG_UNDEFINED) /*< no rlag max hint, use config */
{
rlag_max = rses_get_max_replication_lag(rses);
}
/**
* Search suitable backend server, get DCB in target_dcb
*/
succp = get_dcb(&target_dcb, rses, BE_SLAVE, NULL,rlag_max);
if (succp)
{
#if defined(SS_EXTRA_DEBUG)
MXS_INFO("Found DCB for slave.");
#endif
ss_dassert(get_root_master_bref(rses) ==
rses->rses_master_ref);
atomic_add(&inst->stats.n_slave, 1);
}
else
{
MXS_INFO("Was supposed to route to slave"
"but finding suitable one "
"failed.");
}
}
else if (TARGET_IS_MASTER(route_target))
{
DCB* curr_master_dcb = NULL;
succp = get_dcb(&curr_master_dcb,
rses,
BE_MASTER,
NULL,
MAX_RLAG_UNDEFINED);
if (succp && master_dcb == curr_master_dcb)
{
atomic_add(&inst->stats.n_master, 1);
target_dcb = master_dcb;
}
else
{
if (succp && master_dcb != curr_master_dcb)
{
MXS_INFO("Was supposed to route to master "
"but master has changed.");
}
else
{
MXS_INFO("Was supposed to route to master "
"but couldn't find master in a "
"suitable state.");
}
/**
* Master has changed. Return with error indicator.
*/
rses_end_locked_router_action(rses);
succp = false;
goto retblock;
}
}
if (succp) /*< Have DCB of the target backend */
{
backend_ref_t* bref;
sescmd_cursor_t* scur;
bref = get_bref_from_dcb(rses, target_dcb);
scur = &bref->bref_sescmd_cur;
ss_dassert(target_dcb != NULL);
MXS_INFO("Route query to %s \t%s:%d <",
(SERVER_IS_MASTER(bref->bref_backend->backend_server) ?
"master" : "slave"),
bref->bref_backend->backend_server->name,
bref->bref_backend->backend_server->port);
/**
* Store current stmt if execution of previous session command
* haven't completed yet.
*
* !!! Note that according to MySQL protocol
* there can only be one such non-sescmd stmt at the time.
* It is possible that bref->bref_pending_cmd includes a pending
* command if rwsplit is parent or child for another router,
* which runs all the same commands.
*
* If the assertion below traps, pending queries are treated
* somehow wrong, or client is sending more queries before
* previous is received.
*/
if (sescmd_cursor_is_active(scur))
{
ss_dassert(bref->bref_pending_cmd == NULL);
bref->bref_pending_cmd = gwbuf_clone(querybuf);
rses_end_locked_router_action(rses);
goto retblock;
}
if ((ret = target_dcb->func.write(target_dcb, gwbuf_clone(querybuf))) == 1)
{
backend_ref_t* bref;
atomic_add(&inst->stats.n_queries, 1);
/**
* Add one query response waiter to backend reference
*/
bref = get_bref_from_dcb(rses, target_dcb);
bref_set_state(bref, BREF_QUERY_ACTIVE);
bref_set_state(bref, BREF_WAITING_RESULT);
}
else
{
MXS_ERROR("Routing query failed.");
succp = false;
}
}
rses_end_locked_router_action(rses);
retblock:
#if defined(SS_DEBUG2)
{
char* canonical_query_str;
canonical_query_str = skygw_get_canonical(querybuf);
if (canonical_query_str != NULL)
{
MXS_INFO("Canonical version: %s", canonical_query_str);
free(canonical_query_str);
}
}
#endif
return succp;
}
/**
* @node Acquires lock to router client session if it is not closed.
*
* Parameters:
* @param rses - in, use
*
*
* @return true if router session was not closed. If return value is true
* it means that router is locked, and must be unlocked later. False, if
* router was closed before lock was acquired.
*
*
* @details (write detailed description here)
*
*/
static bool rses_begin_locked_router_action(
ROUTER_CLIENT_SES* rses)
{
bool succp = false;
if(rses == NULL)
return false;
CHK_CLIENT_RSES(rses);
if (rses->rses_closed) {
goto return_succp;
}
spinlock_acquire(&rses->rses_lock);
if (rses->rses_closed) {
spinlock_release(&rses->rses_lock);
goto return_succp;
}
succp = true;
return_succp:
return succp;
}
/** to be inline'd */
/**
* @node Releases router client session lock.
*
* Parameters:
* @param rses - <usage>
* <description>
*
* @return void
*
*
* @details (write detailed description here)
*
*/
static void rses_end_locked_router_action(
ROUTER_CLIENT_SES* rses)
{
CHK_CLIENT_RSES(rses);
spinlock_release(&rses->rses_lock);
}
/**
* Diagnostics routine
*
* Print query router statistics to the DCB passed in
*
* @param instance The router instance
* @param dcb The DCB for diagnostic output
*/
static void
diagnostic(ROUTER *instance, DCB *dcb)
{
ROUTER_CLIENT_SES *router_cli_ses;
ROUTER_INSTANCE *router = (ROUTER_INSTANCE *)instance;
int i = 0;
BACKEND *backend;
char *weightby;
double master_pct = 0.0;
spinlock_acquire(&router->lock);
router_cli_ses = router->connections;
while (router_cli_ses)
{
i++;
router_cli_ses = router_cli_ses->next;
}
spinlock_release(&router->lock);
if(router->stats.n_master + router->stats.n_slave > 0)
{
master_pct = (double)router->stats.n_master/(double)(router->stats.n_master + router->stats.n_slave);
}
dcb_printf(dcb,
"\tNumber of router sessions: %d\n",
router->stats.n_sessions);
dcb_printf(dcb,
"\tCurrent no. of router sessions: %d\n",
i);
dcb_printf(dcb,
"\tNumber of queries forwarded: %d\n",
router->stats.n_queries);
dcb_printf(dcb,
"\tNumber of queries forwarded to master: %d\n",
router->stats.n_master);
dcb_printf(dcb,
"\tNumber of queries forwarded to slave: %d\n",
router->stats.n_slave);
dcb_printf(dcb,
"\tNumber of queries forwarded to all: %d\n",
router->stats.n_all);
dcb_printf(dcb,
"\tMaster/Slave percentage: %.2f%%\n",
master_pct * 100.0);
if ((weightby = serviceGetWeightingParameter(router->service)) != NULL)
{
dcb_printf(dcb,
"\tConnection distribution based on %s "
"server parameter.\n", weightby);
dcb_printf(dcb,
"\t\tServer Target %% Connections "
"Operations\n");
dcb_printf(dcb,
"\t\t Global Router\n");
for (i = 0; router->servers[i]; i++)
{
backend = router->servers[i];
dcb_printf(dcb,
"\t\t%-20s %3.1f%% %-6d %-6d %d\n",
backend->backend_server->unique_name,
(float)backend->weight / 10,
backend->backend_server->stats.n_current,
backend->backend_conn_count,
backend->backend_server->stats.n_current_ops);
}
}
}
/**
* Client Reply routine
*
* The routine will reply to client for session change with master server data
*
* @param instance The router instance
* @param router_session The router session
* @param backend_dcb The backend DCB
* @param queue The GWBUF with reply data
*/
static void clientReply (
ROUTER* instance,
void* router_session,
GWBUF* writebuf,
DCB* backend_dcb)
{
DCB* client_dcb;
ROUTER_INSTANCE* router_inst;
ROUTER_CLIENT_SES* router_cli_ses;
sescmd_cursor_t* scur = NULL;
backend_ref_t* bref;
router_cli_ses = (ROUTER_CLIENT_SES *)router_session;
router_inst = (ROUTER_INSTANCE*)instance;
CHK_CLIENT_RSES(router_cli_ses);
/**
* Lock router client session for secure read of router session members.
* Note that this could be done without lock by using version #
*/
if (!rses_begin_locked_router_action(router_cli_ses))
{
print_error_packet(router_cli_ses, writebuf, backend_dcb);
goto lock_failed;
}
/** Holding lock ensures that router session remains open */
ss_dassert(backend_dcb->session != NULL);
client_dcb = backend_dcb->session->client;
/** Unlock */
rses_end_locked_router_action(router_cli_ses);
/**
* 1. Check if backend received reply to sescmd.
* 2. Check sescmd's state whether OK_PACKET has been
* sent to client already and if not, lock property cursor,
* reply to client, and move property cursor forward. Finally
* release the lock.
* 3. If reply for this sescmd is sent, lock property cursor
* and
*/
if (client_dcb == NULL)
{
while ((writebuf = gwbuf_consume(
writebuf,
GWBUF_LENGTH(writebuf))) != NULL);
/** Log that client was closed before reply */
goto lock_failed;
}
/** Lock router session */
if (!rses_begin_locked_router_action(router_cli_ses))
{
/** Log to debug that router was closed */
goto lock_failed;
}
bref = get_bref_from_dcb(router_cli_ses, backend_dcb);
#if !defined(FOR_BUG548_FIX_ONLY)
/** This makes the issue becoming visible in poll.c */
if (bref == NULL)
{
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
goto lock_failed;
}
#endif
CHK_BACKEND_REF(bref);
scur = &bref->bref_sescmd_cur;
/**
* Active cursor means that reply is from session command
* execution.
*/
if (sescmd_cursor_is_active(scur))
{
if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_ERR) &&
MYSQL_IS_ERROR_PACKET(((uint8_t *)GWBUF_DATA(writebuf))))
{
uint8_t* buf =
(uint8_t *)GWBUF_DATA((scur->scmd_cur_cmd->my_sescmd_buf));
uint8_t* replybuf = (uint8_t *)GWBUF_DATA(writebuf);
size_t len = MYSQL_GET_PACKET_LEN(buf);
size_t replylen = MYSQL_GET_PACKET_LEN(replybuf);
char* cmdstr = strndup(&((char *)buf)[5], len-4);
char* err = strndup(&((char *)replybuf)[8], 5);
char* replystr = strndup(&((char *)replybuf)[13],
replylen-4-5);
ss_dassert(len+4 == GWBUF_LENGTH(scur->scmd_cur_cmd->my_sescmd_buf));
MXS_ERROR("Failed to execute %s in %s:%d. %s %s",
cmdstr,
bref->bref_backend->backend_server->name,
bref->bref_backend->backend_server->port,
err,
replystr);
free(cmdstr);
free(err);
free(replystr);
}
if (GWBUF_IS_TYPE_SESCMD_RESPONSE(writebuf))
{
/**
* Discard all those responses that have already been sent to
* the client. Return with buffer including response that
* needs to be sent to client or NULL.
*/
bool rconn = false;
writebuf = sescmd_cursor_process_replies(writebuf, bref, &rconn);
if(rconn && !router_inst->rwsplit_config.rw_disable_sescmd_hist)
{
select_connect_backend_servers(&router_cli_ses->rses_master_ref,
router_cli_ses->rses_backend_ref,
router_cli_ses->rses_nbackends,
router_cli_ses->rses_config.rw_max_slave_conn_count,
router_cli_ses->rses_config.rw_max_slave_replication_lag,
router_cli_ses->rses_config.rw_slave_select_criteria,
router_cli_ses->rses_master_ref->bref_dcb->session,
router_cli_ses->router);
}
}
/**
* If response will be sent to client, decrease waiter count.
* This applies to session commands only. Counter decrement
* for other type of queries is done outside this block.
*/
if (writebuf != NULL && client_dcb != NULL)
{
/** Set response status as replied */
bref_clear_state(bref, BREF_WAITING_RESULT);
}
}
/**
* Clear BREF_QUERY_ACTIVE flag and decrease waiter counter.
* This applies for queries other than session commands.
*/
else if (BREF_IS_QUERY_ACTIVE(bref))
{
bref_clear_state(bref, BREF_QUERY_ACTIVE);
/** Set response status as replied */
bref_clear_state(bref, BREF_WAITING_RESULT);
}
if (writebuf != NULL && client_dcb != NULL)
{
/** Write reply to client DCB */
SESSION_ROUTE_REPLY(backend_dcb->session, writebuf);
}
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
/** Lock router session */
if (!rses_begin_locked_router_action(router_cli_ses))
{
/** Log to debug that router was closed */
goto lock_failed;
}
/** There is one pending session command to be executed. */
if (sescmd_cursor_is_active(scur))
{
bool succp;
MXS_INFO("Backend %s:%d processed reply and starts to execute "
"active cursor.",
bref->bref_backend->backend_server->name,
bref->bref_backend->backend_server->port);
succp = execute_sescmd_in_backend(bref);
ss_dassert(succp);
if(!succp)
{
MXS_INFO("Backend %s:%d failed to execute session command.",
bref->bref_backend->backend_server->name,
bref->bref_backend->backend_server->port);
}
}
else if (bref->bref_pending_cmd != NULL) /*< non-sescmd is waiting to be routed */
{
int ret;
CHK_GWBUF(bref->bref_pending_cmd);
if ((ret = bref->bref_dcb->func.write(
bref->bref_dcb,
gwbuf_clone(bref->bref_pending_cmd))) == 1)
{
ROUTER_INSTANCE* inst = (ROUTER_INSTANCE *)instance;
atomic_add(&inst->stats.n_queries, 1);
/**
* Add one query response waiter to backend reference
*/
bref_set_state(bref, BREF_QUERY_ACTIVE);
bref_set_state(bref, BREF_WAITING_RESULT);
}
else
{
char* sql = modutil_get_SQL(bref->bref_pending_cmd);
if (sql)
{
MXS_ERROR("Routing query \"%s\" failed.", sql);
free(sql);
}
else
{
MXS_ERROR("Failed to route query.");
}
}
gwbuf_free(bref->bref_pending_cmd);
bref->bref_pending_cmd = NULL;
}
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
lock_failed:
return;
}
/** Compare nunmber of connections from this router in backend servers */
int bref_cmp_router_conn(
const void* bref1,
const void* bref2)
{
BACKEND* b1 = ((backend_ref_t *)bref1)->bref_backend;
BACKEND* b2 = ((backend_ref_t *)bref2)->bref_backend;
return ((1000 * b1->backend_conn_count) / b1->weight)
- ((1000 * b2->backend_conn_count) / b2->weight);
}
/** Compare nunmber of global connections in backend servers */
int bref_cmp_global_conn(
const void* bref1,
const void* bref2)
{
BACKEND* b1 = ((backend_ref_t *)bref1)->bref_backend;
BACKEND* b2 = ((backend_ref_t *)bref2)->bref_backend;
return ((1000 * b1->backend_server->stats.n_current) / b1->weight)
- ((1000 * b2->backend_server->stats.n_current) / b2->weight);
}
/** Compare relication lag between backend servers */
int bref_cmp_behind_master(
const void* bref1,
const void* bref2)
{
BACKEND* b1 = ((backend_ref_t *)bref1)->bref_backend;
BACKEND* b2 = ((backend_ref_t *)bref2)->bref_backend;
return ((b1->backend_server->rlag < b2->backend_server->rlag) ? -1 :
((b1->backend_server->rlag > b2->backend_server->rlag) ? 1 : 0));
}
/** Compare nunmber of current operations in backend servers */
int bref_cmp_current_load(
const void* bref1,
const void* bref2)
{
SERVER* s1 = ((backend_ref_t *)bref1)->bref_backend->backend_server;
SERVER* s2 = ((backend_ref_t *)bref2)->bref_backend->backend_server;
BACKEND* b1 = ((backend_ref_t *)bref1)->bref_backend;
BACKEND* b2 = ((backend_ref_t *)bref2)->bref_backend;
return ((1000 * s1->stats.n_current_ops) - b1->weight)
- ((1000 * s2->stats.n_current_ops) - b2->weight);
}
static void bref_clear_state(
backend_ref_t* bref,
bref_state_t state)
{
if(bref == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return;
}
if (state != BREF_WAITING_RESULT)
{
bref->bref_state &= ~state;
}
else
{
int prev1;
int prev2;
/** Decrease waiter count */
prev1 = atomic_add(&bref->bref_num_result_wait, -1);
if (prev1 <= 0) {
atomic_add(&bref->bref_num_result_wait, 1);
}
else
{
/** Decrease global operation count */
prev2 = atomic_add(
&bref->bref_backend->backend_server->stats.n_current_ops, -1);
ss_dassert(prev2 > 0);
if(prev2 <= 0)
{
MXS_ERROR("[%s] Error: negative current operation count in backend %s:%u",
__FUNCTION__,
bref->bref_backend->backend_server->name,
bref->bref_backend->backend_server->port);
}
}
}
}
static void bref_set_state(
backend_ref_t* bref,
bref_state_t state)
{
if(bref == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return;
}
if (state != BREF_WAITING_RESULT)
{
bref->bref_state |= state;
}
else
{
int prev1;
int prev2;
/** Increase waiter count */
prev1 = atomic_add(&bref->bref_num_result_wait, 1);
ss_dassert(prev1 >= 0);
if(prev1 < 0)
{
MXS_ERROR("[%s] Error: negative number of connections waiting for "
"results in backend %s:%u",
__FUNCTION__,
bref->bref_backend->backend_server->name,
bref->bref_backend->backend_server->port);
}
/** Increase global operation count */
prev2 = atomic_add(
&bref->bref_backend->backend_server->stats.n_current_ops, 1);
ss_dassert(prev2 >= 0);
if(prev2 < 0)
{
MXS_ERROR("[%s] Error: negative current operation count in backend %s:%u",
__FUNCTION__,
bref->bref_backend->backend_server->name,
bref->bref_backend->backend_server->port);
}
}
}
/**
* @node Search suitable backend servers from those of router instance.
*
* Parameters:
* @param p_master_ref - in, use, out
* Pointer to location where master's backend reference is to be stored.
* NULL is not allowed.
*
* @param backend_ref - in, use, out
* Pointer to backend server reference object array.
* NULL is not allowed.
*
* @param router_nservers - in, use
* Number of backend server pointers pointed to by b.
*
* @param max_nslaves - in, use
* Upper limit for the number of slaves. Configuration parameter or default.
*
* @param max_slave_rlag - in, use
* Maximum allowed replication lag for any slave. Configuration parameter or default.
*
* @param session - in, use
* MaxScale session pointer used when connection to backend is established.
*
* @param router - in, use
* Pointer to router instance. Used when server states are qualified.
*
* @return true, if at least one master and one slave was found.
*
*
* @details It is assumed that there is only one master among servers of
* a router instance. As a result, the first master found is chosen.
* There will possibly be more backend references than connected backends
* because only those in correct state are connected to.
*/
static bool select_connect_backend_servers(
backend_ref_t** p_master_ref,
backend_ref_t* backend_ref,
int router_nservers,
int max_nslaves,
int max_slave_rlag,
select_criteria_t select_criteria,
SESSION* session,
ROUTER_INSTANCE* router)
{
bool succp = true;
bool master_found;
bool master_connected;
int slaves_found = 0;
int slaves_connected = 0;
int i;
const int min_nslaves = 0; /*< not configurable at the time */
bool is_synced_master;
int (*p)(const void *, const void *);
BACKEND* master_host;
if (p_master_ref == NULL || backend_ref == NULL)
{
ss_dassert(FALSE);
succp = false;
goto return_succp;
}
/* get the root Master */
master_host = get_root_master(backend_ref, router_nservers);
/**
* Existing session : master is already chosen and connected.
* The function was called because new slave must be selected to replace
* failed one.
*/
if (*p_master_ref != NULL)
{
/**
* Ensure that backend reference is in use, stored master is
* still current root master.
*/
if (!BREF_IS_IN_USE((*p_master_ref)) ||
!SERVER_IS_MASTER((*p_master_ref)->bref_backend->backend_server) ||
master_host != (*p_master_ref)->bref_backend)
{
succp = false;
goto return_succp;
}
master_found = true;
master_connected = true;
}
/**
* New session : select master and slaves
*/
else
{
master_found = false;
master_connected = false;
}
/** Check slave selection criteria and set compare function */
p = criteria_cmpfun[select_criteria];
if (p == NULL)
{
succp = false;
goto return_succp;
}
if (router->bitvalue != 0) /*< 'synced' is the only bitvalue in rwsplit */
{
is_synced_master = true;
}
else
{
is_synced_master = false;
}
#if defined(EXTRA_SS_DEBUG)
MXS_INFO("Servers and conns before ordering:");
for (i=0; i<router_nservers; i++)
{
BACKEND* b = backend_ref[i].bref_backend;
MXS_INFO("master bref %p bref %p %d %s %d:%d",
*p_master_ref,
&backend_ref[i],
backend_ref[i].bref_state,
b->backend_server->name,
b->backend_server->port,
b->backend_conn_count);
}
#endif
/**
* Sort the pointer list to servers according to connection counts. As
* a consequence those backends having least connections are in the
* beginning of the list.
*/
qsort(backend_ref, (size_t)router_nservers, sizeof(backend_ref_t), p);
if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_INFO))
{
if (select_criteria == LEAST_GLOBAL_CONNECTIONS ||
select_criteria == LEAST_ROUTER_CONNECTIONS ||
select_criteria == LEAST_BEHIND_MASTER ||
select_criteria == LEAST_CURRENT_OPERATIONS)
{
MXS_INFO("Servers and %s connection counts:",
select_criteria == LEAST_GLOBAL_CONNECTIONS ?
"all MaxScale" : "router");
for (i=0; i<router_nservers; i++)
{
BACKEND* b = backend_ref[i].bref_backend;
switch(select_criteria) {
case LEAST_GLOBAL_CONNECTIONS:
MXS_INFO("MaxScale connections : %d in \t%s:%d %s",
b->backend_server->stats.n_current,
b->backend_server->name,
b->backend_server->port,
STRSRVSTATUS(b->backend_server));
break;
case LEAST_ROUTER_CONNECTIONS:
MXS_INFO("RWSplit connections : %d in \t%s:%d %s",
b->backend_conn_count,
b->backend_server->name,
b->backend_server->port,
STRSRVSTATUS(b->backend_server));
break;
case LEAST_CURRENT_OPERATIONS:
MXS_INFO("current operations : %d in \t%s:%d %s",
b->backend_server->stats.n_current_ops,
b->backend_server->name,
b->backend_server->port,
STRSRVSTATUS(b->backend_server));
break;
case LEAST_BEHIND_MASTER:
MXS_INFO("replication lag : %d in \t%s:%d %s",
b->backend_server->rlag,
b->backend_server->name,
b->backend_server->port,
STRSRVSTATUS(b->backend_server));
default:
break;
}
}
}
} /*< log only */
/**
* Choose at least 1+min_nslaves (master and slave) and at most 1+max_nslaves
* servers from the sorted list. First master found is selected.
*/
for (i=0;
i<router_nservers &&
(slaves_connected < max_nslaves || !master_connected);
i++)
{
BACKEND* b = backend_ref[i].bref_backend;
if (router->servers[i]->weight == 0)
{
continue;
}
if (SERVER_IS_RUNNING(b->backend_server) &&
((b->backend_server->status & router->bitmask) ==
router->bitvalue))
{
/* check also for relay servers and don't take the master_host */
if (slaves_found < max_nslaves &&
(max_slave_rlag == MAX_RLAG_UNDEFINED ||
(b->backend_server->rlag != MAX_RLAG_NOT_AVAILABLE &&
b->backend_server->rlag <= max_slave_rlag)) &&
(SERVER_IS_SLAVE(b->backend_server) ||
SERVER_IS_RELAY_SERVER(b->backend_server)) &&
(master_host != NULL &&
(b->backend_server != master_host->backend_server)))
{
if(BREF_HAS_FAILED(&backend_ref[i]))
{
continue;
}
slaves_found += 1;
/** Slave is already connected */
if (BREF_IS_IN_USE((&backend_ref[i])))
{
slaves_connected += 1;
}
/** New slave connection is taking place */
else
{
backend_ref[i].bref_dcb = dcb_connect(
b->backend_server,
session,
b->backend_server->protocol);
if (backend_ref[i].bref_dcb != NULL)
{
slaves_connected += 1;
/**
* Start executing session command
* history.
*/
execute_sescmd_history(&backend_ref[i]);
/**
* Here we actually say : When this
* type of issue occurs (DCB_REASON_...)
* for this particular DCB,
* call this function.
*/
dcb_add_callback(
backend_ref[i].bref_dcb,
DCB_REASON_NOT_RESPONDING,
&router_handle_state_switch,
(void *)&backend_ref[i]);
backend_ref[i].bref_state = 0;
bref_set_state(&backend_ref[i],
BREF_IN_USE);
/**
* Increase backend connection counter.
* Server's stats are _increased_ in
* dcb.c:dcb_alloc !
* But decreased in the calling function
* of dcb_close.
*/
atomic_add(&b->backend_conn_count, 1);
}
else
{
MXS_ERROR("Unable to establish "
"connection with slave %s:%d",
b->backend_server->name,
b->backend_server->port);
/* handle connect error */
}
}
}
/* take the master_host for master */
else if (master_host &&
(b->backend_server == master_host->backend_server))
{
/**
* *p_master_ref must be assigned with this
* backend_ref pointer because its original value
* may have been lost when backend references were
* sorted (qsort).
*/
*p_master_ref = &backend_ref[i];
if (master_connected)
{
continue;
}
master_found = true;
backend_ref[i].bref_dcb = dcb_connect(
b->backend_server,
session,
b->backend_server->protocol);
if (backend_ref[i].bref_dcb != NULL)
{
master_connected = true;
/**
* When server fails, this callback
* is called.
*/
dcb_add_callback(
backend_ref[i].bref_dcb,
DCB_REASON_NOT_RESPONDING,
&router_handle_state_switch,
(void *)&backend_ref[i]);
backend_ref[i].bref_state = 0;
bref_set_state(&backend_ref[i],
BREF_IN_USE);
/** Increase backend connection counters */
atomic_add(&b->backend_conn_count, 1);
}
else
{
succp = false;
MXS_ERROR("Unable to establish "
"connection with master %s:%d",
b->backend_server->name,
b->backend_server->port);
/** handle connect error */
}
}
}
} /*< for */
#if defined(EXTRA_SS_DEBUG)
MXS_INFO("Servers and conns after ordering:");
for (i=0; i<router_nservers; i++)
{
BACKEND* b = backend_ref[i].bref_backend;
MXS_INFO("master bref %p bref %p %d %s %d:%d",
*p_master_ref,
&backend_ref[i],
backend_ref[i].bref_state,
b->backend_server->name,
b->backend_server->port,
b->backend_conn_count);
}
/* assert with master_host */
ss_dassert(!master_connected ||
(master_host && ((*p_master_ref)->bref_backend->backend_server == master_host->backend_server) &&
SERVER_MASTER));
#endif
/**
* Successful cases
*/
if (master_connected &&
slaves_connected >= min_nslaves &&
slaves_connected <= max_nslaves)
{
succp = true;
if (slaves_connected == 0 && slaves_found > 0)
{
#if defined(SS_EXTRA_DEBUG)
MXS_WARNING("Couldn't connect to any of the %d "
"slaves. Routing to %s only.",
slaves_found,
(is_synced_master ? "Galera nodes" : "Master"));
#endif
}
else if (slaves_found == 0)
{
#if defined(SS_EXTRA_DEBUG)
MXS_WARNING("Couldn't find any slaves from existing "
"%d servers. Routing to %s only.",
router_nservers,
(is_synced_master ? "Galera nodes" : "Master"));
#endif
}
else if (slaves_connected < max_nslaves)
{
MXS_INFO("Couldn't connect to maximum number of "
"slaves. Connected successfully to %d slaves "
"of %d of them.",
slaves_connected,
slaves_found);
}
if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_INFO))
{
for (i=0; i<router_nservers; i++)
{
BACKEND* b = backend_ref[i].bref_backend;
if (BREF_IS_IN_USE((&backend_ref[i])))
{
MXS_INFO("Selected %s in \t%s:%d",
STRSRVSTATUS(b->backend_server),
b->backend_server->name,
b->backend_server->port);
}
} /* for */
}
}
/**
* Failure cases
*/
else
{
succp = false;
if (!master_found)
{
MXS_ERROR("Couldn't find suitable %s from %d "
"candidates.",
(is_synced_master ? "Galera node" : "Master"),
router_nservers);
}
else if (!master_connected)
{
MXS_ERROR("Couldn't connect to any %s although "
"there exists at least one %s node in the "
"cluster.",
(is_synced_master ? "Galera node" : "Master"),
(is_synced_master ? "Galera node" : "Master"));
}
if (slaves_connected < min_nslaves)
{
MXS_ERROR("Couldn't establish required amount of "
"slave connections for router session.");
}
/** Clean up connections */
for (i=0; i<router_nservers; i++)
{
if (BREF_IS_IN_USE((&backend_ref[i])))
{
ss_dassert(backend_ref[i].bref_backend->backend_conn_count > 0);
/** disconnect opened connections */
bref_clear_state(&backend_ref[i], BREF_IN_USE);
/** Decrease backend's connection counter. */
atomic_add(&backend_ref[i].bref_backend->backend_conn_count, -1);
dcb_close(backend_ref[i].bref_dcb);
}
}
}
return_succp:
return succp;
}
/**
* Create a generic router session property strcture.
*/
static rses_property_t* rses_property_init(
rses_property_type_t prop_type)
{
rses_property_t* prop;
prop = (rses_property_t*)calloc(1, sizeof(rses_property_t));
if (prop == NULL)
{
MXS_ERROR("Error: Malloc returned NULL. (%s:%d)",__FILE__,__LINE__);
return NULL;
}
prop->rses_prop_type = prop_type;
#if defined(SS_DEBUG)
prop->rses_prop_chk_top = CHK_NUM_ROUTER_PROPERTY;
prop->rses_prop_chk_tail = CHK_NUM_ROUTER_PROPERTY;
#endif
CHK_RSES_PROP(prop);
return prop;
}
/**
* Property is freed at the end of router client session.
*/
static void rses_property_done(
rses_property_t* prop)
{
if(prop == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return;
}
CHK_RSES_PROP(prop);
switch (prop->rses_prop_type) {
case RSES_PROP_TYPE_SESCMD:
mysql_sescmd_done(&prop->rses_prop_data.sescmd);
break;
case RSES_PROP_TYPE_TMPTABLES:
hashtable_free(prop->rses_prop_data.temp_tables);
break;
default:
MXS_DEBUG("%lu [rses_property_done] Unknown property type %d "
"in property %p",
pthread_self(),
prop->rses_prop_type,
prop);
ss_dassert(false);
break;
}
free(prop);
}
/**
* Add property to the router_client_ses structure's rses_properties
* array. The slot is determined by the type of property.
* In each slot there is a list of properties of similar type.
*
* Router client session must be locked.
*/
static int rses_property_add(
ROUTER_CLIENT_SES* rses,
rses_property_t* prop)
{
if(rses == NULL)
{
MXS_ERROR("Router client session is NULL. (%s:%d)",__FILE__,__LINE__);
return -1;
}
if(prop == NULL)
{
MXS_ERROR("Router client session property is NULL. (%s:%d)",__FILE__,__LINE__);
return -1;
}
rses_property_t* p;
CHK_CLIENT_RSES(rses);
CHK_RSES_PROP(prop);
ss_dassert(SPINLOCK_IS_LOCKED(&rses->rses_lock));
prop->rses_prop_rsession = rses;
p = rses->rses_properties[prop->rses_prop_type];
if (p == NULL)
{
rses->rses_properties[prop->rses_prop_type] = prop;
}
else
{
while (p->rses_prop_next != NULL)
{
p = p->rses_prop_next;
}
p->rses_prop_next = prop;
}
return 0;
}
/**
* Router session must be locked.
* Return session command pointer if succeed, NULL if failed.
*/
static mysql_sescmd_t* rses_property_get_sescmd(
rses_property_t* prop)
{
mysql_sescmd_t* sescmd;
if(prop == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return NULL;
}
CHK_RSES_PROP(prop);
ss_dassert(prop->rses_prop_rsession == NULL ||
SPINLOCK_IS_LOCKED(&prop->rses_prop_rsession->rses_lock));
sescmd = &prop->rses_prop_data.sescmd;
if (sescmd != NULL)
{
CHK_MYSQL_SESCMD(sescmd);
}
return sescmd;
}
/**
* Create session command property.
*/
static mysql_sescmd_t* mysql_sescmd_init (
rses_property_t* rses_prop,
GWBUF* sescmd_buf,
unsigned char packet_type,
ROUTER_CLIENT_SES* rses)
{
mysql_sescmd_t* sescmd;
CHK_RSES_PROP(rses_prop);
/** Can't call rses_property_get_sescmd with uninitialized sescmd */
sescmd = &rses_prop->rses_prop_data.sescmd;
sescmd->my_sescmd_prop = rses_prop; /*< reference to owning property */
#if defined(SS_DEBUG)
sescmd->my_sescmd_chk_top = CHK_NUM_MY_SESCMD;
sescmd->my_sescmd_chk_tail = CHK_NUM_MY_SESCMD;
#endif
/** Set session command buffer */
sescmd->my_sescmd_buf = sescmd_buf;
sescmd->my_sescmd_packet_type = packet_type;
sescmd->position = atomic_add(&rses->pos_generator,1);
return sescmd;
}
static void mysql_sescmd_done(
mysql_sescmd_t* sescmd)
{
if(sescmd == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return;
}
CHK_RSES_PROP(sescmd->my_sescmd_prop);
gwbuf_free(sescmd->my_sescmd_buf);
memset(sescmd, 0, sizeof(mysql_sescmd_t));
}
/**
* All cases where backend message starts at least with one response to session
* command are handled here.
* Read session commands from property list. If command is already replied,
* discard packet. Else send reply to client. In both cases move cursor forward
* until all session command replies are handled.
*
* Cases that are expected to happen and which are handled:
* s = response not yet replied to client, S = already replied response,
* q = query
* 1. q+ for example : select * from mysql.user
* 2. s+ for example : set autocommit=1
* 3. S+
* 4. sq+
* 5. Sq+
* 6. Ss+
* 7. Ss+q+
* 8. S+q+
* 9. s+q+
*/
static GWBUF* sescmd_cursor_process_replies(
GWBUF* replybuf,
backend_ref_t* bref,
bool *reconnect)
{
mysql_sescmd_t* scmd;
sescmd_cursor_t* scur;
ROUTER_CLIENT_SES* ses;
scur = &bref->bref_sescmd_cur;
ss_dassert(SPINLOCK_IS_LOCKED(&(scur->scmd_cur_rses->rses_lock)));
scmd = sescmd_cursor_get_command(scur);
ses = (*scur->scmd_cur_ptr_property)->rses_prop_rsession;
CHK_GWBUF(replybuf);
/**
* Walk through packets in the message and the list of session
* commands.
*/
while (scmd != NULL && replybuf != NULL)
{
bref->reply_cmd = *((unsigned char*)replybuf->start + 4);
scur->position = scmd->position;
/** Faster backend has already responded to client : discard */
if (scmd->my_sescmd_is_replied)
{
bool last_packet = false;
CHK_GWBUF(replybuf);
while (!last_packet)
{
int buflen;
buflen = GWBUF_LENGTH(replybuf);
last_packet = GWBUF_IS_TYPE_RESPONSE_END(replybuf);
/** discard packet */
replybuf = gwbuf_consume(replybuf, buflen);
}
/** Set response status received */
bref_clear_state(bref, BREF_WAITING_RESULT);
if(bref->reply_cmd != scmd->reply_cmd)
{
MXS_INFO("Backend server '%s' response differs from master's response. "
"Closing connection.",
bref->bref_backend->backend_server->unique_name);
sescmd_cursor_set_active(scur,false);
bref_clear_state(bref,BREF_QUERY_ACTIVE);
bref_clear_state(bref,BREF_IN_USE);
bref_set_state(bref,BREF_CLOSED);
bref_set_state(bref,BREF_SESCMD_FAILED);
if(bref->bref_dcb)
dcb_close(bref->bref_dcb);
*reconnect = true;
if(replybuf)
while((replybuf = gwbuf_consume(replybuf,gwbuf_length(replybuf))));
}
}
/** This is a response from the master and it is the "right" one.
* A slave server's response will be compared to this and if
* their response differs from the master server's response, they
* are dropped from the valid list of backend servers.
* Response is in the buffer and it will be sent to client. */
else if(ses->rses_master_ref->bref_dcb == bref->bref_dcb)
{
/** Mark the rest session commands as replied */
scmd->my_sescmd_is_replied = true;
scmd->reply_cmd = *((unsigned char*)replybuf->start + 4);
MXS_INFO("Master '%s' responded to a session command.",
bref->bref_backend->backend_server->unique_name);
int i;
for(i=0;i<ses->rses_nbackends;i++)
{
if(!BREF_IS_WAITING_RESULT(&ses->rses_backend_ref[i]))
{
/** This backend has already received a response */
if(ses->rses_backend_ref[i].reply_cmd !=
scmd->reply_cmd &&
!BREF_IS_CLOSED(&ses->rses_backend_ref[i]))
{
bref_clear_state(&ses->rses_backend_ref[i],BREF_QUERY_ACTIVE);
bref_clear_state(&ses->rses_backend_ref[i],BREF_IN_USE);
bref_set_state(&ses->rses_backend_ref[i],BREF_CLOSED);
bref_set_state(bref,BREF_SESCMD_FAILED);
if(ses->rses_backend_ref[i].bref_dcb)
dcb_close(ses->rses_backend_ref[i].bref_dcb);
*reconnect = true;
MXS_INFO("Disabling slave %s:%d, result differs from "
"master's result. Master: %d Slave: %d",
ses->rses_backend_ref[i].bref_backend->backend_server->name,
ses->rses_backend_ref[i].bref_backend->backend_server->port,
bref->reply_cmd,
ses->rses_backend_ref[i].reply_cmd);
}
}
}
}
else
{
MXS_INFO("Slave '%s' responded before master to a session command. Result: %d",
bref->bref_backend->backend_server->unique_name,
(int)bref->reply_cmd);
if(bref->reply_cmd == 0xff)
{
SERVER* serv = bref->bref_backend->backend_server;
MXS_ERROR("Slave '%s' (%s:%u) failed to execute session command.",
serv->unique_name,serv->name,serv->port);
}
if(replybuf)
while((replybuf = gwbuf_consume(replybuf,gwbuf_length(replybuf))));
}
if (sescmd_cursor_next(scur))
{
scmd = sescmd_cursor_get_command(scur);
}
else
{
scmd = NULL;
/** All session commands are replied */
scur->scmd_cur_active = false;
}
}
ss_dassert(replybuf == NULL || *scur->scmd_cur_ptr_property == NULL);
return replybuf;
}
/**
* Get the address of current session command.
*
* Router session must be locked */
static mysql_sescmd_t* sescmd_cursor_get_command(
sescmd_cursor_t* scur)
{
mysql_sescmd_t* scmd;
ss_dassert(SPINLOCK_IS_LOCKED(&(scur->scmd_cur_rses->rses_lock)));
scur->scmd_cur_cmd = rses_property_get_sescmd(*scur->scmd_cur_ptr_property);
CHK_MYSQL_SESCMD(scur->scmd_cur_cmd);
scmd = scur->scmd_cur_cmd;
return scmd;
}
/** router must be locked */
static bool sescmd_cursor_is_active(
sescmd_cursor_t* sescmd_cursor)
{
bool succp;
if(sescmd_cursor == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return false;
}
ss_dassert(SPINLOCK_IS_LOCKED(&sescmd_cursor->scmd_cur_rses->rses_lock));
succp = sescmd_cursor->scmd_cur_active;
return succp;
}
/** router must be locked */
static void sescmd_cursor_set_active(
sescmd_cursor_t* sescmd_cursor,
bool value)
{
ss_dassert(SPINLOCK_IS_LOCKED(&sescmd_cursor->scmd_cur_rses->rses_lock));
/** avoid calling unnecessarily */
ss_dassert(sescmd_cursor->scmd_cur_active != value);
sescmd_cursor->scmd_cur_active = value;
}
/**
* Clone session command's command buffer.
* Router session must be locked
*/
static GWBUF* sescmd_cursor_clone_querybuf(
sescmd_cursor_t* scur)
{
GWBUF* buf;
if(scur == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return NULL;
}
ss_dassert(scur->scmd_cur_cmd != NULL);
buf = gwbuf_clone_all(scur->scmd_cur_cmd->my_sescmd_buf);
CHK_GWBUF(buf);
return buf;
}
static bool sescmd_cursor_history_empty(
sescmd_cursor_t* scur)
{
bool succp;
if(scur == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return true;
}
CHK_SESCMD_CUR(scur);
if (scur->scmd_cur_rses->rses_properties[RSES_PROP_TYPE_SESCMD] == NULL)
{
succp = true;
}
else
{
succp = false;
}
return succp;
}
static void sescmd_cursor_reset(
sescmd_cursor_t* scur)
{
ROUTER_CLIENT_SES* rses;
if(scur == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return;
}
CHK_SESCMD_CUR(scur);
CHK_CLIENT_RSES(scur->scmd_cur_rses);
rses = scur->scmd_cur_rses;
scur->scmd_cur_ptr_property = &rses->rses_properties[RSES_PROP_TYPE_SESCMD];
CHK_RSES_PROP((*scur->scmd_cur_ptr_property));
scur->scmd_cur_active = false;
scur->scmd_cur_cmd = &(*scur->scmd_cur_ptr_property)->rses_prop_data.sescmd;
}
static bool execute_sescmd_history(
backend_ref_t* bref)
{
bool succp;
sescmd_cursor_t* scur;
if(bref == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return false;
}
CHK_BACKEND_REF(bref);
scur = &bref->bref_sescmd_cur;
CHK_SESCMD_CUR(scur);
if (!sescmd_cursor_history_empty(scur))
{
sescmd_cursor_reset(scur);
succp = execute_sescmd_in_backend(bref);
}
else
{
succp = true;
}
return succp;
}
/**
* If session command cursor is passive, sends the command to backend for
* execution.
*
* Returns true if command was sent or added successfully to the queue.
* Returns false if command sending failed or if there are no pending session
* commands.
*
* Router session must be locked.
*/
static bool execute_sescmd_in_backend(
backend_ref_t* backend_ref)
{
DCB* dcb;
bool succp;
int rc = 0;
sescmd_cursor_t* scur;
GWBUF* buf;
if(backend_ref == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return false;
}
if (BREF_IS_CLOSED(backend_ref))
{
succp = false;
goto return_succp;
}
dcb = backend_ref->bref_dcb;
CHK_DCB(dcb);
CHK_BACKEND_REF(backend_ref);
/**
* Get cursor pointer and copy of command buffer to cursor.
*/
scur = &backend_ref->bref_sescmd_cur;
/** Return if there are no pending ses commands */
if (sescmd_cursor_get_command(scur) == NULL)
{
succp = false;
MXS_INFO("Cursor had no pending session commands.");
goto return_succp;
}
if (!sescmd_cursor_is_active(scur))
{
/** Cursor is left active when function returns. */
sescmd_cursor_set_active(scur, true);
}
switch (scur->scmd_cur_cmd->my_sescmd_packet_type) {
case MYSQL_COM_CHANGE_USER:
/** This makes it possible to handle replies correctly */
gwbuf_set_type(scur->scmd_cur_cmd->my_sescmd_buf, GWBUF_TYPE_SESCMD);
buf = sescmd_cursor_clone_querybuf(scur);
rc = dcb->func.auth(
dcb,
NULL,
dcb->session,
buf);
break;
case MYSQL_COM_INIT_DB:
{
/**
* Record database name and store to session.
*/
GWBUF* tmpbuf;
MYSQL_session* data;
unsigned int qlen;
data = dcb->session->data;
tmpbuf = scur->scmd_cur_cmd->my_sescmd_buf;
qlen = MYSQL_GET_PACKET_LEN((unsigned char*)tmpbuf->start);
memset(data->db,0,MYSQL_DATABASE_MAXLEN+1);
if(qlen > 0 && qlen < MYSQL_DATABASE_MAXLEN+1)
strncpy(data->db,tmpbuf->start+5,qlen - 1);
}
/** Fallthrough */
case MYSQL_COM_QUERY:
default:
/**
* Mark session command buffer, it triggers writing
* MySQL command to protocol
*/
gwbuf_set_type(scur->scmd_cur_cmd->my_sescmd_buf, GWBUF_TYPE_SESCMD);
buf = sescmd_cursor_clone_querybuf(scur);
rc = dcb->func.write(
dcb,
buf);
break;
}
if (rc == 1)
{
succp = true;
}
else
{
succp = false;
}
return_succp:
return succp;
}
/**
* Moves cursor to next property and copied address of its sescmd to cursor.
* Current propery must be non-null.
* If current property is the last on the list, *scur->scmd_ptr_property == NULL
*
* Router session must be locked
*/
static bool sescmd_cursor_next(
sescmd_cursor_t* scur)
{
bool succp = false;
rses_property_t* prop_curr;
rses_property_t* prop_next;
if(scur == NULL)
{
MXS_ERROR("[%s] Error: NULL parameter.",__FUNCTION__);
return false;
}
ss_dassert(scur != NULL);
ss_dassert(*(scur->scmd_cur_ptr_property) != NULL);
ss_dassert(SPINLOCK_IS_LOCKED(
&(*(scur->scmd_cur_ptr_property))->rses_prop_rsession->rses_lock));
/** Illegal situation */
if (scur == NULL ||
*scur->scmd_cur_ptr_property == NULL ||
scur->scmd_cur_cmd == NULL)
{
/** Log error */
goto return_succp;
}
prop_curr = *(scur->scmd_cur_ptr_property);
CHK_MYSQL_SESCMD(scur->scmd_cur_cmd);
ss_dassert(prop_curr == mysql_sescmd_get_property(scur->scmd_cur_cmd));
CHK_RSES_PROP(prop_curr);
/** Copy address of pointer to next property */
scur->scmd_cur_ptr_property = &(prop_curr->rses_prop_next);
prop_next = *scur->scmd_cur_ptr_property;
ss_dassert(prop_next == *(scur->scmd_cur_ptr_property));
/** If there is a next property move forward */
if (prop_next != NULL)
{
CHK_RSES_PROP(prop_next);
CHK_RSES_PROP((*(scur->scmd_cur_ptr_property)));
/** Get pointer to next property's sescmd */
scur->scmd_cur_cmd = rses_property_get_sescmd(prop_next);
ss_dassert(prop_next == scur->scmd_cur_cmd->my_sescmd_prop);
CHK_MYSQL_SESCMD(scur->scmd_cur_cmd);
CHK_RSES_PROP(scur->scmd_cur_cmd->my_sescmd_prop);
}
else
{
/** No more properties, can't proceed. */
goto return_succp;
}
if (scur->scmd_cur_cmd != NULL)
{
succp = true;
}
else
{
ss_dassert(false); /*< Log error, sescmd shouldn't be NULL */
}
return_succp:
return succp;
}
static rses_property_t* mysql_sescmd_get_property(
mysql_sescmd_t* scmd)
{
CHK_MYSQL_SESCMD(scmd);
return scmd->my_sescmd_prop;
}
static void tracelog_routed_query(
ROUTER_CLIENT_SES* rses,
char* funcname,
backend_ref_t* bref,
GWBUF* buf)
{
uint8_t* packet = GWBUF_DATA(buf);
unsigned char packet_type = packet[4];
size_t len;
size_t buflen = GWBUF_LENGTH(buf);
char* querystr;
char* startpos = (char *)&packet[5];
BACKEND* b;
backend_type_t be_type;
DCB* dcb;
CHK_BACKEND_REF(bref);
b = bref->bref_backend;
CHK_BACKEND(b);
dcb = bref->bref_dcb;
CHK_DCB(dcb);
be_type = BACKEND_TYPE(b);
if (GWBUF_IS_TYPE_MYSQL(buf))
{
len = packet[0];
len += 256*packet[1];
len += 256*256*packet[2];
if (packet_type == '\x03')
{
querystr = (char *)malloc(len);
memcpy(querystr, startpos, len-1);
querystr[len-1] = '\0';
MXS_DEBUG("%lu [%s] %d bytes long buf, \"%s\" -> %s:%d %s dcb %p",
pthread_self(),
funcname,
(int)buflen,
querystr,
b->backend_server->name,
b->backend_server->port,
STRBETYPE(be_type),
dcb);
free(querystr);
}
else if (packet_type == '\x22' ||
packet_type == 0x22 ||
packet_type == '\x26' ||
packet_type == 0x26 ||
true)
{
querystr = (char *)malloc(len);
memcpy(querystr, startpos, len-1);
querystr[len-1] = '\0';
MXS_DEBUG("%lu [%s] %d bytes long buf, \"%s\" -> %s:%d %s dcb %p",
pthread_self(),
funcname,
(int)buflen,
querystr,
b->backend_server->name,
b->backend_server->port,
STRBETYPE(be_type),
dcb);
free(querystr);
}
}
gwbuf_free(buf);
}
/**
* Return RCAP_TYPE_STMT_INPUT.
*/
static int getCapabilities ()
{
return RCAP_TYPE_STMT_INPUT;
}
/**
* Execute in backends used by current router session.
* Save session variable commands to router session property
* struct. Thus, they can be replayed in backends which are
* started and joined later.
*
* Suppress redundant OK packets sent by backends.
*
* The first OK packet is replied to the client.
*
* @param router_cli_ses Client's router session pointer
* @param querybuf GWBUF including the query to be routed
* @param inst Router instance
* @param packet_type Type of MySQL packet
* @param qtype Query type from query_classifier
*
* @return True if at least one backend is used and routing succeed to all
* backends being used, otherwise false.
*
*/
static bool route_session_write(
ROUTER_CLIENT_SES* router_cli_ses,
GWBUF* querybuf,
ROUTER_INSTANCE* inst,
unsigned char packet_type,
skygw_query_type_t qtype)
{
bool succp;
rses_property_t* prop;
backend_ref_t* backend_ref;
int i;
int max_nslaves;
int nbackends;
int nsucc;
MXS_INFO("Session write, routing to all servers.");
/** Maximum number of slaves in this router client session */
max_nslaves = rses_get_max_slavecount(router_cli_ses,
router_cli_ses->rses_nbackends);
nsucc = 0;
nbackends = 0;
backend_ref = router_cli_ses->rses_backend_ref;
/**
* These are one-way messages and server doesn't respond to them.
* Therefore reply processing is unnecessary and session
* command property is not needed. It is just routed to all available
* backends.
*/
if (packet_type == MYSQL_COM_STMT_SEND_LONG_DATA ||
packet_type == MYSQL_COM_QUIT ||
packet_type == MYSQL_COM_STMT_CLOSE)
{
int rc;
/** Lock router session */
if (!rses_begin_locked_router_action(router_cli_ses))
{
goto return_succp;
}
for (i=0; i<router_cli_ses->rses_nbackends; i++)
{
DCB* dcb = backend_ref[i].bref_dcb;
if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_INFO) &&
BREF_IS_IN_USE((&backend_ref[i])))
{
MXS_INFO("Route query to %s \t%s:%d%s",
(SERVER_IS_MASTER(backend_ref[i].bref_backend->backend_server) ?
"master" : "slave"),
backend_ref[i].bref_backend->backend_server->name,
backend_ref[i].bref_backend->backend_server->port,
(i+1==router_cli_ses->rses_nbackends ? " <" : " "));
}
if (BREF_IS_IN_USE((&backend_ref[i])))
{
nbackends += 1;
if ((rc = dcb->func.write(dcb, gwbuf_clone(querybuf))) == 1)
{
nsucc += 1;
}
}
}
rses_end_locked_router_action(router_cli_ses);
gwbuf_free(querybuf);
goto return_succp;
}
/** Lock router session */
if (!rses_begin_locked_router_action(router_cli_ses))
{
goto return_succp;
}
if (router_cli_ses->rses_nbackends <= 0)
{
MXS_INFO("Router session doesn't have any backends in use. "
"Routing failed. <");
goto return_succp;
}
if (router_cli_ses->rses_config.rw_max_sescmd_history_size > 0 &&
router_cli_ses->rses_nsescmd >= router_cli_ses->rses_config.rw_max_sescmd_history_size)
{
MXS_WARNING("Router session exceeded session command history limit. "
"Slave recovery is disabled and only slave servers with "
"consistent session state are used "
"for the duration of the session.");
router_cli_ses->rses_config.rw_disable_sescmd_hist = true;
router_cli_ses->rses_config.rw_max_sescmd_history_size = 0;
}
if(router_cli_ses->rses_config.rw_disable_sescmd_hist)
{
rses_property_t *prop, *tmp;
backend_ref_t* bref;
bool conflict;
prop = router_cli_ses->rses_properties[RSES_PROP_TYPE_SESCMD];
while(prop)
{
conflict = false;
for(i = 0;i<router_cli_ses->rses_nbackends;i++)
{
bref = &backend_ref[i];
if(BREF_IS_IN_USE(bref))
{
if(bref->bref_sescmd_cur.position <= prop->rses_prop_data.sescmd.position + 1)
{
conflict = true;
break;
}
}
}
if(conflict)
{
break;
}
tmp = prop;
router_cli_ses->rses_properties[RSES_PROP_TYPE_SESCMD] = prop->rses_prop_next;
rses_property_done(tmp);
prop = router_cli_ses->rses_properties[RSES_PROP_TYPE_SESCMD];
}
}
/**
* Additional reference is created to querybuf to
* prevent it from being released before properties
* are cleaned up as a part of router sessionclean-up.
*/
if((prop = rses_property_init(RSES_PROP_TYPE_SESCMD)) == NULL)
{
MXS_ERROR("Router session property initialization failed");
rses_end_locked_router_action(router_cli_ses);
return false;
}
mysql_sescmd_init(prop, querybuf, packet_type, router_cli_ses);
/** Add sescmd property to router client session */
if(rses_property_add(router_cli_ses, prop) != 0)
{
MXS_ERROR("Session property addition failed.");
rses_end_locked_router_action(router_cli_ses);
return false;
}
for (i=0; i<router_cli_ses->rses_nbackends; i++)
{
if (BREF_IS_IN_USE((&backend_ref[i])))
{
sescmd_cursor_t* scur;
nbackends += 1;
if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_INFO))
{
MXS_INFO("Route query to %s \t%s:%d%s",
(SERVER_IS_MASTER(backend_ref[i].bref_backend->backend_server) ?
"master" : "slave"),
backend_ref[i].bref_backend->backend_server->name,
backend_ref[i].bref_backend->backend_server->port,
(i+1==router_cli_ses->rses_nbackends ? " <" : " "));
}
scur = backend_ref_get_sescmd_cursor(&backend_ref[i]);
/**
* Add one waiter to backend reference.
*/
bref_set_state(get_bref_from_dcb(router_cli_ses,
backend_ref[i].bref_dcb),
BREF_WAITING_RESULT);
/**
* Start execution if cursor is not already executing.
* Otherwise, cursor will execute pending commands
* when it completes with previous commands.
*/
if (sescmd_cursor_is_active(scur))
{
nsucc += 1;
MXS_INFO("Backend %s:%d already executing sescmd.",
backend_ref[i].bref_backend->backend_server->name,
backend_ref[i].bref_backend->backend_server->port);
}
else
{
if (execute_sescmd_in_backend(&backend_ref[i]))
{
nsucc += 1;
}
else
{
MXS_ERROR("Failed to execute session "
"command in %s:%d",
backend_ref[i].bref_backend->backend_server->name,
backend_ref[i].bref_backend->backend_server->port);
}
}
}
}
atomic_add(&router_cli_ses->rses_nsescmd,1);
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
return_succp:
/**
* Routing must succeed to all backends that are used.
* There must be at leas one and at most max_nslaves+1 backends.
*/
succp = (nbackends > 0 && nsucc == nbackends && nbackends <= max_nslaves+1);
return succp;
}
#if defined(NOT_USED)
static bool router_option_configured(
ROUTER_INSTANCE* router,
const char* optionstr,
void* data)
{
bool succp = false;
char** option;
option = router->service->routerOptions;
while (option != NULL)
{
char* value;
if ((value = strchr(options[i], '=')) == NULL)
{
break;
}
else
{
*value = 0;
value++;
if (strcmp(options[i], "slave_selection_criteria") == 0)
{
if (GET_SELECT_CRITERIA(value) == (select_criteria_t *)*data)
{
succp = true;
break;
}
}
}
}
return succp;
}
#endif /*< NOT_USED */
static void rwsplit_process_router_options(
ROUTER_INSTANCE* router,
char** options)
{
int i;
char* value;
select_criteria_t c;
if(options == NULL)
return;
for (i = 0; options[i]; i++)
{
if ((value = strchr(options[i], '=')) == NULL)
{
MXS_ERROR("Unsupported router option \"%s\" for "
"readwritesplit router.",
options[i]);
}
else
{
*value = 0;
value++;
if (strcmp(options[i], "slave_selection_criteria") == 0)
{
c = GET_SELECT_CRITERIA(value);
ss_dassert(
c == LEAST_GLOBAL_CONNECTIONS ||
c == LEAST_ROUTER_CONNECTIONS ||
c == LEAST_BEHIND_MASTER ||
c == LEAST_CURRENT_OPERATIONS ||
c == UNDEFINED_CRITERIA);
if (c == UNDEFINED_CRITERIA)
{
MXS_WARNING("Unknown "
"slave selection criteria \"%s\". "
"Allowed values are LEAST_GLOBAL_CONNECTIONS, "
"LEAST_ROUTER_CONNECTIONS, "
"LEAST_BEHIND_MASTER,"
"and LEAST_CURRENT_OPERATIONS.",
STRCRITERIA(router->rwsplit_config.rw_slave_select_criteria));
}
else
{
router->rwsplit_config.rw_slave_select_criteria = c;
}
}
else if(strcmp(options[i], "max_sescmd_history") == 0)
{
router->rwsplit_config.rw_max_sescmd_history_size = atoi(value);
}
else if(strcmp(options[i],"disable_sescmd_history") == 0)
{
router->rwsplit_config.rw_disable_sescmd_hist = config_truth_value(value);
}
else if(strcmp(options[i],"master_accept_reads") == 0)
{
router->rwsplit_config.rw_master_reads = config_truth_value(value);
}
}
} /*< for */
}
/**
* Error Handler routine to resolve _backend_ failures. If it succeeds then there
* are enough operative backends available and connected. Otherwise it fails,
* and session is terminated.
*
* @param instance The router instance
* @param router_session The router session
* @param errmsgbuf The error message to reply
* @param backend_dcb The backend DCB
* @param action The action: ERRACT_NEW_CONNECTION or ERRACT_REPLY_CLIENT
* @param succp Result of action: true iff router can continue
*
* Even if succp == true connecting to new slave may have failed. succp is to
* tell whether router has enough master/slave connections to continue work.
*/
static void handleError (
ROUTER* instance,
void* router_session,
GWBUF* errmsgbuf,
DCB* problem_dcb,
error_action_t action,
bool* succp)
{
SESSION* session;
ROUTER_INSTANCE* inst = (ROUTER_INSTANCE *)instance;
ROUTER_CLIENT_SES* rses = (ROUTER_CLIENT_SES *)router_session;
CHK_DCB(problem_dcb);
/** Don't handle same error twice on same DCB */
if (problem_dcb->dcb_errhandle_called)
{
/** we optimistically assume that previous call succeed */
/*
* The return of true is potentially misleading, but appears to
* be safe with the code as it stands on 9 Sept 2015 - MNB
*/
*succp = true;
return;
}
else
{
problem_dcb->dcb_errhandle_called = true;
}
session = problem_dcb->session;
if (session == NULL || rses == NULL)
{
*succp = false;
}
else if (dcb_isclient(problem_dcb))
{
*succp = false;
}
else
{
CHK_SESSION(session);
CHK_CLIENT_RSES(rses);
switch (action) {
case ERRACT_NEW_CONNECTION:
{
SERVER* srv;
if (!rses_begin_locked_router_action(rses))
{
*succp = false;
break;
}
srv = rses->rses_master_ref->bref_backend->backend_server;
/**
* If master has lost its Master status error can't be
* handled so that session could continue.
*/
if (rses->rses_master_ref->bref_dcb == problem_dcb &&
!SERVER_IS_MASTER(srv))
{
backend_ref_t* bref;
bref = get_bref_from_dcb(rses, problem_dcb);
if (bref != NULL)
{
CHK_BACKEND_REF(bref);
bref_clear_state(bref, BREF_IN_USE);
bref_set_state(bref, BREF_CLOSED);
}
else
{
MXS_ERROR("server %s:%d lost the "
"master status but could not locate the "
"corresponding backend ref.",
srv->name,
srv->port);
dcb_close(problem_dcb);
}
if (!srv->master_err_is_logged)
{
MXS_ERROR("server %s:%d lost the "
"master status. Readwritesplit "
"service can't locate the master. "
"Client sessions will be closed.",
srv->name,
srv->port);
srv->master_err_is_logged = true;
}
*succp = false;
}
else
{
/**
* This is called in hope of getting replacement for
* failed slave(s). This call may free rses.
*/
*succp = handle_error_new_connection(inst,
&rses,
problem_dcb,
errmsgbuf);
}
/* Free the lock if rses still exists */
if (rses) rses_end_locked_router_action(rses);
break;
}
case ERRACT_REPLY_CLIENT:
{
handle_error_reply_client(session,
rses,
problem_dcb,
errmsgbuf);
*succp = false; /*< no new backend servers were made available */
break;
}
default:
*succp = false;
break;
}
}
dcb_close(problem_dcb);
}
static void handle_error_reply_client(
SESSION* ses,
ROUTER_CLIENT_SES* rses,
DCB* backend_dcb,
GWBUF* errmsg)
{
session_state_t sesstate;
DCB* client_dcb;
backend_ref_t* bref;
spinlock_acquire(&ses->ses_lock);
sesstate = ses->state;
client_dcb = ses->client;
spinlock_release(&ses->ses_lock);
/**
* If bref exists, mark it closed
*/
if ((bref = get_bref_from_dcb(rses, backend_dcb)) != NULL)
{
CHK_BACKEND_REF(bref);
bref_clear_state(bref, BREF_IN_USE);
bref_set_state(bref, BREF_CLOSED);
}
if (sesstate == SESSION_STATE_ROUTER_READY)
{
CHK_DCB(client_dcb);
client_dcb->func.write(client_dcb, gwbuf_clone(errmsg));
}
}
/**
* Check if there is backend reference pointing at failed DCB, and reset its
* flags. Then clear DCB's callback and finally : try to find replacement(s)
* for failed slave(s).
*
* This must be called with router lock.
*
* @param inst router instance
* @param rses router client session
* @param dcb failed DCB
* @param errmsg error message which is sent to client if it is waiting
*
* @return true if there are enough backend connections to continue, false if not
*/
static bool handle_error_new_connection(
ROUTER_INSTANCE* inst,
ROUTER_CLIENT_SES** rses,
DCB* backend_dcb,
GWBUF* errmsg)
{
ROUTER_CLIENT_SES* myrses;
SESSION* ses;
int router_nservers;
int max_nslaves;
int max_slave_rlag;
backend_ref_t* bref;
bool succp;
myrses = *rses;
ss_dassert(SPINLOCK_IS_LOCKED(&myrses->rses_lock));
ses = backend_dcb->session;
CHK_SESSION(ses);
/**
* If bref == NULL it has been replaced already with another one.
*/
if ((bref = get_bref_from_dcb(myrses, backend_dcb)) == NULL)
{
succp = true;
goto return_succp;
}
CHK_BACKEND_REF(bref);
/**
* If query was sent through the bref and it is waiting for reply from
* the backend server it is necessary to send an error to the client
* because it is waiting for reply.
*/
if (BREF_IS_WAITING_RESULT(bref))
{
DCB* client_dcb;
client_dcb = ses->client;
client_dcb->func.write(client_dcb, gwbuf_clone(errmsg));
bref_clear_state(bref, BREF_WAITING_RESULT);
}
bref_clear_state(bref, BREF_IN_USE);
bref_set_state(bref, BREF_CLOSED);
/**
* Error handler is already called for this DCB because
* it's not polling anymore. It can be assumed that
* it succeed because rses isn't closed.
*/
if (backend_dcb->state != DCB_STATE_POLLING)
{
succp = true;
goto return_succp;
}
/**
* Remove callback because this DCB won't be used
* unless it is reconnected later, and then the callback
* is set again.
*/
dcb_remove_callback(backend_dcb,
DCB_REASON_NOT_RESPONDING,
&router_handle_state_switch,
(void *)bref);
router_nservers = router_get_servercount(inst);
max_nslaves = rses_get_max_slavecount(myrses, router_nservers);
max_slave_rlag = rses_get_max_replication_lag(myrses);
/**
* Try to get replacement slave or at least the minimum
* number of slave connections for router session.
*/
if(inst->rwsplit_config.rw_disable_sescmd_hist)
{
succp = have_enough_servers(&myrses,1,router_nservers,inst) ? true : false;
}
else
{
succp = select_connect_backend_servers(
&myrses->rses_master_ref,
myrses->rses_backend_ref,
router_nservers,
max_nslaves,
max_slave_rlag,
myrses->rses_config.rw_slave_select_criteria,
ses,
inst);
}
return_succp:
return succp;
}
static void print_error_packet(
ROUTER_CLIENT_SES* rses,
GWBUF* buf,
DCB* dcb)
{
#if defined(SS_DEBUG)
if (GWBUF_IS_TYPE_MYSQL(buf))
{
while (gwbuf_length(buf) > 0)
{
/**
* This works with MySQL protocol only !
* Protocol specific packet print functions would be nice.
*/
uint8_t* ptr = GWBUF_DATA(buf);
size_t len = MYSQL_GET_PACKET_LEN(ptr);
if (MYSQL_GET_COMMAND(ptr) == 0xff)
{
SERVER* srv = NULL;
backend_ref_t* bref = rses->rses_backend_ref;
int i;
char* bufstr;
for (i=0; i<rses->rses_nbackends; i++)
{
if (bref[i].bref_dcb == dcb)
{
srv = bref[i].bref_backend->backend_server;
}
}
ss_dassert(srv != NULL);
char* str = (char*)&ptr[7];
bufstr = strndup(str, len-3);
MXS_ERROR("Backend server %s:%d responded with "
"error : %s",
srv->name,
srv->port,
bufstr);
free(bufstr);
}
buf = gwbuf_consume(buf, len+4);
}
}
else
{
while ((buf = gwbuf_consume(buf, GWBUF_LENGTH(buf))) != NULL);
}
#endif /*< SS_DEBUG */
}
static int router_get_servercount(
ROUTER_INSTANCE* inst)
{
int router_nservers = 0;
BACKEND** b = inst->servers;
/** count servers */
while (*(b++) != NULL) router_nservers++;
return router_nservers;
}
static bool have_enough_servers(
ROUTER_CLIENT_SES** p_rses,
const int min_nsrv,
int router_nsrv,
ROUTER_INSTANCE* router)
{
bool succp;
/** With too few servers session is not created */
if (router_nsrv < min_nsrv ||
MAX((*p_rses)->rses_config.rw_max_slave_conn_count,
(router_nsrv*(*p_rses)->rses_config.rw_max_slave_conn_percent)/100)
< min_nsrv)
{
if (router_nsrv < min_nsrv)
{
MXS_ERROR("Unable to start %s service. There are "
"too few backend servers available. Found %d "
"when %d is required.",
router->service->name,
router_nsrv,
min_nsrv);
}
else
{
int pct = (*p_rses)->rses_config.rw_max_slave_conn_percent/100;
int nservers = router_nsrv*pct;
if ((*p_rses)->rses_config.rw_max_slave_conn_count < min_nsrv)
{
MXS_ERROR("Unable to start %s service. There are "
"too few backend servers configured in "
"MaxScale.cnf. Found %d when %d is required.",
router->service->name,
(*p_rses)->rses_config.rw_max_slave_conn_count,
min_nsrv);
}
if (nservers < min_nsrv)
{
double dbgpct = ((double)min_nsrv/(double)router_nsrv)*100.0;
MXS_ERROR("Unable to start %s service. There are "
"too few backend servers configured in "
"MaxScale.cnf. Found %d%% when at least %.0f%% "
"would be required.",
router->service->name,
(*p_rses)->rses_config.rw_max_slave_conn_percent,
dbgpct);
}
}
free(*p_rses);
*p_rses = NULL;
succp = false;
}
else
{
succp = true;
}
return succp;
}
/**
* Find out the number of read backend servers.
* Depending on the configuration value type, either copy direct count
* of slave connections or calculate the count from percentage value.
*/
static int rses_get_max_slavecount(
ROUTER_CLIENT_SES* rses,
int router_nservers)
{
int conf_max_nslaves;
int max_nslaves;
CHK_CLIENT_RSES(rses);
if (rses->rses_config.rw_max_slave_conn_count > 0)
{
conf_max_nslaves = rses->rses_config.rw_max_slave_conn_count;
}
else
{
conf_max_nslaves =
(router_nservers*rses->rses_config.rw_max_slave_conn_percent)/100;
}
max_nslaves = MIN(router_nservers-1, MAX(1, conf_max_nslaves));
return max_nslaves;
}
static int rses_get_max_replication_lag(
ROUTER_CLIENT_SES* rses)
{
int conf_max_rlag;
CHK_CLIENT_RSES(rses);
/** if there is no configured value, then longest possible int is used */
if (rses->rses_config.rw_max_slave_replication_lag > 0)
{
conf_max_rlag = rses->rses_config.rw_max_slave_replication_lag;
}
else
{
conf_max_rlag = ~(1<<31);
}
return conf_max_rlag;
}
/**
* Finds out if there is a backend reference pointing at the DCB given as
* parameter.
* @param rses router client session
* @param dcb DCB
*
* @return backend reference pointer if succeed or NULL
*/
static backend_ref_t* get_bref_from_dcb(
ROUTER_CLIENT_SES* rses,
DCB* dcb)
{
backend_ref_t* bref;
int i = 0;
CHK_DCB(dcb);
CHK_CLIENT_RSES(rses);
bref = rses->rses_backend_ref;
while (i<rses->rses_nbackends)
{
if (bref->bref_dcb == dcb)
{
break;
}
bref++;
i += 1;
}
if (i == rses->rses_nbackends)
{
bref = NULL;
}
return bref;
}
/**
* Calls hang-up function for DCB if it is not both running and in
* master/slave/joined/ndb role. Called by DCB's callback routine.
*/
static int router_handle_state_switch(
DCB* dcb,
DCB_REASON reason,
void* data)
{
backend_ref_t* bref;
int rc = 1;
SERVER* srv;
CHK_DCB(dcb);
if (NULL == dcb->session->router_session)
{
/*
* The following processing will fail if there is no router session,
* because the "data" parameter will not contain meaningful data,
* so we have no choice but to stop here.
*/
return 0;
}
bref = (backend_ref_t *)data;
CHK_BACKEND_REF(bref);
srv = bref->bref_backend->backend_server;
if (SERVER_IS_RUNNING(srv) && SERVER_IS_IN_CLUSTER(srv))
{
goto return_rc;
}
MXS_DEBUG("%lu [router_handle_state_switch] %s %s:%d in state %s",
pthread_self(),
STRDCBREASON(reason),
srv->name,
srv->port,
STRSRVSTATUS(srv));
CHK_SESSION(((SESSION*)dcb->session));
if (dcb->session->router_session)
{
CHK_CLIENT_RSES(((ROUTER_CLIENT_SES *)dcb->session->router_session));
}
switch (reason) {
case DCB_REASON_NOT_RESPONDING:
dcb->func.hangup(dcb);
break;
default:
break;
}
return_rc:
return rc;
}
static sescmd_cursor_t* backend_ref_get_sescmd_cursor (
backend_ref_t* bref)
{
sescmd_cursor_t* scur;
CHK_BACKEND_REF(bref);
scur = &bref->bref_sescmd_cur;
CHK_SESCMD_CUR(scur);
return scur;
}
#if defined(PREP_STMT_CACHING)
#define MAX_STMT_LEN 1024
static prep_stmt_t* prep_stmt_init(
prep_stmt_type_t type,
void* id)
{
prep_stmt_t* pstmt;
pstmt = (prep_stmt_t *)calloc(1, sizeof(prep_stmt_t));
if (pstmt != NULL)
{
#if defined(SS_DEBUG)
pstmt->pstmt_chk_top = CHK_NUM_PREP_STMT;
pstmt->pstmt_chk_tail = CHK_NUM_PREP_STMT;
#endif
pstmt->pstmt_state = PREP_STMT_ALLOC;
pstmt->pstmt_type = type;
if (type == PREP_STMT_NAME)
{
pstmt->pstmt_id.name = strndup((char *)id, MAX_STMT_LEN);
}
else
{
pstmt->pstmt_id.seq = 0;
}
}
CHK_PREP_STMT(pstmt);
return pstmt;
}
static void prep_stmt_done(
prep_stmt_t* pstmt)
{
CHK_PREP_STMT(pstmt);
if (pstmt->pstmt_type == PREP_STMT_NAME)
{
free(pstmt->pstmt_id.name);
}
free(pstmt);
}
static bool prep_stmt_drop(
prep_stmt_t* pstmt)
{
CHK_PREP_STMT(pstmt);
pstmt->pstmt_state = PREP_STMT_DROPPED;
return true;
}
#endif /*< PREP_STMT_CACHING */
/********************************
* This routine returns the root master server from MySQL replication tree
* Get the root Master rule:
*
* find server with the lowest replication depth level
* and the SERVER_MASTER bitval
* Servers are checked even if they are in 'maintenance'
*
* @param servers The list of servers
* @param router_nservers The number of servers
* @return The Master found
*
*/
static BACKEND *get_root_master(
backend_ref_t *servers,
int router_nservers)
{
int i = 0;
BACKEND * master_host = NULL;
for (i = 0; i< router_nservers; i++)
{
BACKEND* b;
if (servers[i].bref_backend == NULL)
{
continue;
}
b = servers[i].bref_backend;
if ((b->backend_server->status &
(SERVER_MASTER|SERVER_MAINT)) == SERVER_MASTER)
{
if (master_host == NULL ||
(b->backend_server->depth < master_host->backend_server->depth))
{
master_host = b;
}
}
}
return master_host;
}
/********************************
* This routine returns the root master server from MySQL replication tree
* Get the root Master rule:
*
* find server with the lowest replication depth level
* and the SERVER_MASTER bitval
* Servers are checked even if they are in 'maintenance'
*
* @param rses pointer to router session
* @return pointer to backend reference of the root master or NULL
*
*/
static backend_ref_t* get_root_master_bref(
ROUTER_CLIENT_SES* rses)
{
backend_ref_t* bref;
backend_ref_t* candidate_bref = NULL;
int i = 0;
bref = rses->rses_backend_ref;
while (i<rses->rses_nbackends)
{
if ((bref->bref_backend->backend_server->status &
(SERVER_MASTER|SERVER_MAINT)) == SERVER_MASTER)
{
if (bref->bref_backend->backend_server->status & SERVER_MASTER)
{
if (candidate_bref == NULL ||
(bref->bref_backend->backend_server->depth <
candidate_bref->bref_backend->backend_server->depth))
{
candidate_bref = bref;
}
}
}
bref++;
i += 1;
}
if (candidate_bref == NULL)
{
MXS_ERROR("Could not find master among the backend "
"servers. Previous master's state : %s",
STRSRVSTATUS(BREFSRV(rses->rses_master_ref)));
}
return candidate_bref;
}
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