Files
MaxScale/server/modules/routing/readwritesplit/readwritesplit.c
2014-03-18 10:54:19 +02:00

1790 lines
59 KiB
C

/*
* This file is distributed as part of the SkySQL Gateway. 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 SkySQL Ab 2013
*/
#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>
extern int lm_enabled_logfiles_bitmask;
/**
* @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
*
* @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 uint8_t getCapabilities (ROUTER* inst, void* router_session);
static bool search_backend_servers(
BACKEND** p_master,
BACKEND** p_slave,
ROUTER_INSTANCE* router);
static ROUTER_OBJECT MyObject = {
createInstance,
newSession,
closeSession,
freeSession,
routeQuery,
diagnostic,
clientReply,
NULL,
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 void 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 sescmd_cursor_t* rses_get_sescmd_cursor(
ROUTER_CLIENT_SES* rses,
backend_type_t be_type);
static bool execute_sescmd_in_backend(
ROUTER_CLIENT_SES* rses,
backend_type_t be_type);
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(
DCB* client_dcb,
GWBUF* replybuf,
sescmd_cursor_t* scur);
static bool cont_exec_sescmd_in_backend(
ROUTER_CLIENT_SES* rses,
backend_type_t be_type);
static void tracelog_routed_query(
ROUTER_CLIENT_SES* rses,
char* funcname,
DCB* dcb,
GWBUF* buf);
static SPINLOCK instlock;
static ROUTER_INSTANCE* instances;
/**
* 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()
{
LOGIF(LM, (skygw_log_write_flush(
LOGFILE_MESSAGE,
"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;
}
/**
* Create an instance of read/write statemtn 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;
int n;
int i;
if ((router = calloc(1, sizeof(ROUTER_INSTANCE))) == NULL) {
return NULL;
}
router->service = service;
spinlock_init(&router->lock);
/** Calculate number of servers */
server = service->databases;
for (n=0; server != NULL; server=server->nextdb) {
n++;
}
router->servers = (BACKEND **)calloc(n + 1, sizeof(BACKEND *));
if (router->servers == NULL)
{
free(router);
return NULL;
}
if (options != NULL)
{
LOGIF(LM, (skygw_log_write_flush(
LOGFILE_MESSAGE,
"Router options supplied to read/write statement router "
"module but none are supported. The options will be "
"ignored.")));
}
/**
* Create an array of the backend servers in the router structure to
* maintain a count of the number of connections to each
* backend server.
*/
server = service->databases;
n = 0;
while (server != NULL) {
if ((router->servers[n] = malloc(sizeof(BACKEND))) == NULL)
{
for (i = 0; i < n; i++) {
free(router->servers[i]);
}
free(router->servers);
free(router);
return NULL;
}
router->servers[n]->backend_server = server;
router->servers[n]->backend_conn_count = 0;
n += 1;
server = server->nextdb;
}
router->servers[n] = NULL;
/**
* 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;
if (options)
{
for (i = 0; options[i]; i++)
{
if (!strcasecmp(options[i], "master"))
{
router->bitmask |= (SERVER_MASTER|SERVER_SLAVE);
router->bitvalue |= SERVER_MASTER;
}
else if (!strcasecmp(options[i], "slave"))
{
router->bitmask |= (SERVER_MASTER|SERVER_SLAVE);
router->bitvalue |= SERVER_SLAVE;
}
else if (!strcasecmp(options[i], "synced"))
{
router->bitmask |= (SERVER_JOINED);
router->bitvalue |= SERVER_JOINED;
}
else
{
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Warning : Unsupported router option %s "
"for readwritesplitrouter.",
options[i])));
}
}
}
/**
* 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* local_backend[BE_COUNT];
ROUTER_CLIENT_SES* client_rses;
ROUTER_INSTANCE* router = (ROUTER_INSTANCE *)router_inst;
bool succp;
client_rses =
(ROUTER_CLIENT_SES *)calloc(1, sizeof(ROUTER_CLIENT_SES));
if (client_rses == NULL)
{
ss_dassert(false);
return NULL;
}
memset(local_backend, 0, BE_COUNT*sizeof(void*));
spinlock_init(&client_rses->rses_lock);
#if defined(SS_DEBUG)
client_rses->rses_chk_top = CHK_NUM_ROUTER_SES;
client_rses->rses_chk_tail = CHK_NUM_ROUTER_SES;
#endif
/** store pointers to sescmd list to both cursors */
client_rses->rses_cursor[BE_MASTER].scmd_cur_rses = client_rses;
client_rses->rses_cursor[BE_MASTER].scmd_cur_active = false;
client_rses->rses_cursor[BE_MASTER].scmd_cur_ptr_property =
&client_rses->rses_properties[RSES_PROP_TYPE_SESCMD];
client_rses->rses_cursor[BE_MASTER].scmd_cur_cmd = NULL;
client_rses->rses_cursor[BE_MASTER].scmd_cur_be_type = BE_MASTER;
client_rses->rses_cursor[BE_SLAVE].scmd_cur_rses = client_rses;
client_rses->rses_cursor[BE_SLAVE].scmd_cur_active = false;
client_rses->rses_cursor[BE_SLAVE].scmd_cur_ptr_property =
&client_rses->rses_properties[RSES_PROP_TYPE_SESCMD];
client_rses->rses_cursor[BE_SLAVE].scmd_cur_cmd = NULL;
client_rses->rses_cursor[BE_SLAVE].scmd_cur_be_type = BE_SLAVE;
/**
* Find a backend server to connect to. This is the extent of the
* load balancing algorithm we need to implement for this simple
* connection router.
*/
succp = search_backend_servers(&local_backend[BE_MASTER],
&local_backend[BE_SLAVE],
router);
/** Both Master and Slave must be found */
if (!succp) {
free(client_rses);
return NULL;
}
/**
* Open the slave connection.
*/
client_rses->rses_dcb[BE_SLAVE] = dcb_connect(
local_backend[BE_SLAVE]->backend_server,
session,
local_backend[BE_SLAVE]->backend_server->protocol);
if (client_rses->rses_dcb[BE_SLAVE] == NULL) {
ss_dassert(session->refcount == 1);
free(client_rses);
return NULL;
}
/**
* Open the master connection.
*/
client_rses->rses_dcb[BE_MASTER] = dcb_connect(
local_backend[BE_MASTER]->backend_server,
session,
local_backend[BE_MASTER]->backend_server->protocol);
if (client_rses->rses_dcb[BE_MASTER] == NULL)
{
/** Close slave connection first. */
client_rses->rses_dcb[BE_SLAVE]->func.close(client_rses->rses_dcb[BE_SLAVE]);
free(client_rses);
return NULL;
}
/**
* We now have a master and a slave server with the least connections.
* Bump the connection counts for these servers.
*/
atomic_add(&local_backend[BE_SLAVE]->backend_conn_count, 1);
atomic_add(&local_backend[BE_MASTER]->backend_conn_count, 1);
client_rses->rses_backend[BE_SLAVE] = local_backend[BE_SLAVE];
client_rses->rses_backend[BE_MASTER] = local_backend[BE_MASTER];
router->stats.n_sessions += 1;
client_rses->rses_capabilities = RCAP_TYPE_STMT_INPUT;
/**
* 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);
CHK_CLIENT_RSES(client_rses);
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;
DCB* slave_dcb;
DCB* master_dcb;
router_cli_ses = (ROUTER_CLIENT_SES *)router_session;
CHK_CLIENT_RSES(router_cli_ses);
/**
* Lock router client session for secure read and update.
*/
if (rses_begin_locked_router_action(router_cli_ses))
{
/* decrease server current connection counters */
atomic_add(&router_cli_ses->rses_backend[BE_SLAVE]->backend_server->stats.n_current, -1);
atomic_add(&router_cli_ses->rses_backend[BE_MASTER]->backend_server->stats.n_current, -1);
slave_dcb = router_cli_ses->slave_dcb;
router_cli_ses->slave_dcb = NULL;
master_dcb = router_cli_ses->master_dcb;
router_cli_ses->master_dcb = NULL;
router_cli_ses->rses_closed = true;
/** Unlock */
rses_end_locked_router_action(router_cli_ses);
/**
* Close the backend server connections
*/
if (slave_dcb != NULL) {
CHK_DCB(slave_dcb);
slave_dcb->func.close(slave_dcb);
}
if (master_dcb != NULL) {
master_dcb->func.close(master_dcb);
CHK_DCB(master_dcb);
}
}
}
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;
atomic_add(&router_cli_ses->rses_backend[BE_SLAVE]->backend_conn_count, -1);
atomic_add(&router_cli_ses->rses_backend[BE_MASTER]->backend_conn_count, -1);
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);
return;
}
/**
* 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 session The session associated with the client
* @param queue Gateway buffer queue with the packets received
*
* @return The number of queries forwarded
*/
static int routeQuery(
ROUTER* instance,
void* router_session,
GWBUF* querybuf)
{
skygw_query_type_t qtype = QUERY_TYPE_UNKNOWN;
GWBUF* plainsqlbuf = NULL;
char* querystr = NULL;
char* startpos;
unsigned char packet_type;
uint8_t* packet;
int ret = 0;
DCB* master_dcb = NULL;
DCB* slave_dcb = NULL;
ROUTER_INSTANCE* inst = (ROUTER_INSTANCE *)instance;
ROUTER_CLIENT_SES* router_cli_ses = (ROUTER_CLIENT_SES *)router_session;
bool rses_is_closed;
rses_property_t* prop;
size_t len;
CHK_CLIENT_RSES(router_cli_ses);
/** Dirty read for quick check if router is closed. */
if (router_cli_ses->rses_closed)
{
rses_is_closed = true;
}
else
{
/*< Lock router client session for secure read of DCBs */
rses_is_closed =
!(rses_begin_locked_router_action(router_cli_ses));
}
if (!rses_is_closed)
{
master_dcb = router_cli_ses->rses_dcb[BE_MASTER];
slave_dcb = router_cli_ses->rses_dcb[BE_SLAVE];
/** unlock */
rses_end_locked_router_action(router_cli_ses);
}
packet = GWBUF_DATA(querybuf);
packet_type = packet[4];
if (rses_is_closed || (master_dcb == NULL && slave_dcb == NULL))
{
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error: Failed to route %s:%s:\"%s\" to "
"backend server. %s.",
STRPACKETTYPE(packet_type),
STRQTYPE(qtype),
(querystr == NULL ? "(empty)" : querystr),
(rses_is_closed ? "Router was closed" :
"Router has no backend servers where to "
"route to"))));
goto return_ret;
}
inst->stats.n_queries++;
startpos = (char *)&packet[5];
switch(packet_type) {
case COM_QUIT: /**< 1 QUIT will close all sessions */
case COM_INIT_DB: /**< 2 DDL must go to the master */
case COM_REFRESH: /**< 7 - I guess this is session but not sure */
case COM_DEBUG: /**< 0d all servers dump debug info to stdout */
case COM_PING: /**< 0e all servers are pinged */
case COM_CHANGE_USER: /**< 11 all servers change it accordingly */
qtype = QUERY_TYPE_SESSION_WRITE;
break;
case COM_CREATE_DB: /**< 5 DDL must go to the master */
case COM_DROP_DB: /**< 6 DDL must go to the master */
qtype = QUERY_TYPE_WRITE;
break;
case COM_QUERY:
plainsqlbuf = gwbuf_clone_transform(querybuf,
GWBUF_TYPE_PLAINSQL);
len = GWBUF_LENGTH(plainsqlbuf);
/** unnecessary if buffer includes additional terminating null */
querystr = (char *)malloc(len+1);
memcpy(querystr, startpos, len);
memset(&querystr[len], 0, 1);
// querystr = (char *)GWBUF_DATA(plainsqlbuf);
/*
querystr = master_dcb->func.getquerystr(
(void *) gwbuf_clone(querybuf),
&querystr_is_copy);
*/
qtype = skygw_query_classifier_get_type(querystr, 0);
break;
case COM_SHUTDOWN: /**< 8 where should shutdown be routed ? */
case COM_STATISTICS: /**< 9 ? */
case COM_PROCESS_INFO: /**< 0a ? */
case COM_CONNECT: /**< 0b ? */
case COM_PROCESS_KILL: /**< 0c ? */
case COM_TIME: /**< 0f should this be run in gateway ? */
case COM_DELAYED_INSERT: /**< 10 ? */
case COM_DAEMON: /**< 1d ? */
default:
break;
} /**< switch by packet type */
LOGIF(LT, (skygw_log_write(LOGFILE_TRACE,
"String\t\"%s\"",
querystr == NULL ? "(empty)" : querystr)));
LOGIF(LT, (skygw_log_write(LOGFILE_TRACE,
"Packet type\t%s",
STRPACKETTYPE(packet_type))));
switch (qtype) {
case QUERY_TYPE_WRITE:
LOGIF(LT, (skygw_log_write(
LOGFILE_TRACE,
"%lu [routeQuery:rwsplit] Query type\t%s, "
"routing to Master.",
pthread_self(),
STRQTYPE(qtype))));
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"routeQuery",
master_dcb,
gwbuf_clone(querybuf)));
ret = master_dcb->func.write(master_dcb, querybuf);
atomic_add(&inst->stats.n_master, 1);
goto return_ret;
break;
case QUERY_TYPE_READ:
LOGIF(LT, (skygw_log_write_flush(
LOGFILE_TRACE,
"%lu [routeQuery:rwsplit] Query type\t%s, "
"routing to Slave.",
pthread_self(),
STRQTYPE(qtype))));
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"routeQuery",
slave_dcb,
gwbuf_clone(querybuf)));
ret = slave_dcb->func.write(slave_dcb, querybuf);
LOGIF(LT, (skygw_log_write_flush(
LOGFILE_TRACE,
"%lu [routeQuery:rwsplit] Routed.",
pthread_self())));
atomic_add(&inst->stats.n_slave, 1);
goto return_ret;
break;
case QUERY_TYPE_SESSION_WRITE:
/**
* 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.
*
* DOES THIS ALL APPLY TO COM_QUIT AS WELL??
*
* The first OK packet is replied to the client.
*
*/
LOGIF(LT, (skygw_log_write(
LOGFILE_TRACE,
"%lu [routeQuery:rwsplit] DCB M:%p s:%p, "
"Query type\t%s, "
"packet type %s, routing to all servers.",
pthread_self(),
master_dcb,
slave_dcb,
STRQTYPE(qtype),
STRPACKETTYPE(packet_type))));
/**
* COM_QUIT is one-way message. Server doesn't respond to that.
* Therefore reply processing is unnecessary and session
* command property is not needed. It is just routed to both
* backends.
*/
if (packet_type == COM_QUIT)
{
int rc;
int rc2;
rc = master_dcb->func.write(master_dcb, gwbuf_clone(querybuf));
rc2 = slave_dcb->func.write(slave_dcb, gwbuf_clone(querybuf));
if (rc == 1 && rc == rc2)
{
ret = 1;
}
goto return_ret;
}
prop = rses_property_init(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.
*/
mysql_sescmd_init(prop, querybuf, packet_type, router_cli_ses);
/** Lock router session */
if (!rses_begin_locked_router_action(router_cli_ses))
{
rses_property_done(prop);
goto return_ret;
}
/** Add sescmd property to router client session */
rses_property_add(router_cli_ses, prop);
/** Execute session command in master */
if (execute_sescmd_in_backend(router_cli_ses, BE_MASTER))
{
ret = 1;
}
else
{
/** Log error */
}
/** Execute session command in slave */
if (execute_sescmd_in_backend(router_cli_ses, BE_SLAVE))
{
ret = 1;
}
else
{
/** Log error */
}
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
atomic_add(&inst->stats.n_all, 1);
goto return_ret;
break;
default:
LOGIF(LT, (skygw_log_write(
LOGFILE_TRACE,
"%lu [routeQuery:rwsplit] Query type\t%s, "
"routing to Master by default.",
pthread_self(),
STRQTYPE(qtype))));
/**
* Is this really ok?
* What is not known is routed to master.
*/
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"routeQuery",
master_dcb,
gwbuf_clone(querybuf)));
ret = master_dcb->func.write(master_dcb, querybuf);
atomic_add(&inst->stats.n_master, 1);
goto return_ret;
break;
} /*< switch by query type */
return_ret:
if (plainsqlbuf != NULL)
{
gwbuf_free(plainsqlbuf);
}
return ret;
}
/** to be inline'd */
/**
* @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;
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:
if (!succp)
{
/** log that router session was closed */
}
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;
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);
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);
}
/**
* 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* master_dcb;
DCB* slave_dcb;
DCB* client_dcb;
ROUTER_CLIENT_SES* router_cli_ses;
sescmd_cursor_t* scur = NULL;
backend_type_t be_type = BE_UNDEFINED;
router_cli_ses = (ROUTER_CLIENT_SES *)router_session;
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))
{
while ((writebuf = gwbuf_consume(
writebuf,
GWBUF_LENGTH(writebuf))) != NULL);
goto lock_failed;
}
master_dcb = router_cli_ses->rses_dcb[BE_MASTER];
slave_dcb = router_cli_ses->rses_dcb[BE_SLAVE];
/** 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 */
return;
}
if (backend_dcb == master_dcb)
{
be_type = BE_MASTER;
}
else if (backend_dcb == slave_dcb)
{
be_type = BE_SLAVE;
}
LOGIF(LT, tracelog_routed_query(router_cli_ses,
"reply_by_statement",
backend_dcb,
gwbuf_clone(writebuf)));
/** Lock router session */
if (!rses_begin_locked_router_action(router_cli_ses))
{
/** Log to debug that router was closed */
goto lock_failed;
}
scur = rses_get_sescmd_cursor(router_cli_ses, be_type);
/**
* Active cursor means that reply is from session command
* execution. Majority of the time there are no session commands
* being executed.
*/
if (sescmd_cursor_is_active(scur))
{
writebuf = sescmd_cursor_process_replies(client_dcb,
writebuf,
scur);
}
/** Unlock router session */
rses_end_locked_router_action(router_cli_ses);
if (writebuf != NULL && client_dcb != NULL)
{
/** Write reply to client DCB */
client_dcb->func.write(client_dcb, writebuf);
LOGIF(LT, (skygw_log_write_flush(
LOGFILE_TRACE,
"%lu [clientReply:rwsplit] client dcb %p, "
"backend dcb %p. End of normal reply.",
pthread_self(),
client_dcb,
backend_dcb)));
}
lock_failed:
return;
}
/**
* @node Search suitable backend server from those of router instance.
*
* Parameters:
* @param p_master - in, use, out
* Pointer to location where master's address is to be stored.
* If NULL, then master is not searched.
*
* @param p_slave - in, use, out
* Pointer to location where slave's address is to be stored.
* if NULL, then slave is not searched.
*
* @param inst - in, use
* Pointer to router instance
*
* @return true, if all what what requested found, false if the request
* was not satisfied or was partially satisfied.
*
*
* @details It is assumed that there is only one master among servers of
* a router instance. As a result, thr first master is always chosen.
*/
static bool search_backend_servers(
BACKEND** p_master,
BACKEND** p_slave,
ROUTER_INSTANCE* router)
{
BACKEND* local_backend[BE_COUNT] = {NULL,NULL};
int i;
bool succp = true;
/*
* Loop over all the servers and find any that have fewer connections
* than current candidate server.
*
* If a server has less connections than the current candidate it is
* chosen to a new candidate.
*
* If a server has the same number of connections currently as the
* candidate and has had less connections over time than the candidate
* it will also become the new candidate. This has the effect of
* spreading the connections over different servers during periods of
* very low load.
*
* If master is searched for, the first master found is chosen.
*/
for (i = 0; router->servers[i] != NULL; i++) {
BACKEND* be = router->servers[i];
if (be != NULL) {
LOGIF(LT, (skygw_log_write(
LOGFILE_TRACE,
"%lu [search_backend_servers] Examine server "
"%s:%d with %d connections. Status is %d, "
"router->bitvalue is %d",
pthread_self(),
be->backend_server->name,
be->backend_server->port,
be->backend_conn_count,
be->backend_server->status,
router->bitmask)));
}
if (be != NULL &&
SERVER_IS_RUNNING(be->backend_server) &&
(be->backend_server->status & router->bitmask) ==
router->bitvalue)
{
if (SERVER_IS_SLAVE(be->backend_server) &&
p_slave != NULL)
{
/**
* If no candidate set, set first running
* server as an initial candidate server.
*/
if (local_backend[BE_SLAVE] == NULL)
{
local_backend[BE_SLAVE] = be;
}
else if (be->backend_conn_count <
local_backend[BE_SLAVE]->backend_conn_count)
{
/**
* This running server has fewer
* connections, set it as a new
* candidate.
*/
local_backend[BE_SLAVE] = be;
}
else if (be->backend_conn_count ==
local_backend[BE_SLAVE]->backend_conn_count &&
be->backend_server->stats.n_connections <
local_backend[BE_SLAVE]->backend_server->stats.n_connections)
{
/**
* This running server has the same
* number of connections currently
* as the candidate but has had
* fewer connections over time
* than candidate, set this server
* to candidate.
*/
local_backend[BE_SLAVE] = be;
}
}
else if (p_master != NULL &&
local_backend[BE_MASTER] == NULL &&
SERVER_IS_MASTER(be->backend_server))
{
local_backend[BE_MASTER] = be;
}
}
}
if (p_slave != NULL && local_backend[BE_SLAVE] == NULL) {
succp = false;
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Couldn't find suitable Slave from %d "
"candidates.",
i)));
}
if (p_master != NULL && local_backend[BE_MASTER] == NULL) {
succp = false;
LOGIF(LE, (skygw_log_write_flush(
LOGFILE_ERROR,
"Error : Couldn't find suitable Master from %d "
"candidates.",
i)));
}
if (local_backend[BE_SLAVE] != NULL) {
*p_slave = local_backend[BE_SLAVE];
LOGIF(LT, (skygw_log_write(
LOGFILE_TRACE,
"%lu [readwritesplit:search_backend_servers] Selected "
"Slave %s:%d from %d candidates.",
pthread_self(),
local_backend[BE_SLAVE]->backend_server->name,
local_backend[BE_SLAVE]->backend_server->port,
i)));
}
if (local_backend[BE_MASTER] != NULL) {
*p_master = local_backend[BE_MASTER];
LOGIF(LT, (skygw_log_write(
LOGFILE_TRACE,
"%lu [readwritesplit:search_backend_servers] Selected "
"Master %s:%d "
"from %d candidates.",
pthread_self(),
local_backend[BE_MASTER]->backend_server->name,
local_backend[BE_MASTER]->backend_server->port,
i)));
}
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)
{
goto return_prop;
}
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
return_prop:
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)
{
CHK_RSES_PROP(prop);
switch (prop->rses_prop_type) {
case RSES_PROP_TYPE_SESCMD:
mysql_sescmd_done(&prop->rses_prop_data.sescmd);
break;
default:
LOGIF(LD, (skygw_log_write_flush(
LOGFILE_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 void rses_property_add(
ROUTER_CLIENT_SES* rses,
rses_property_t* prop)
{
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;
}
}
/**
* 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;
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;
}
/**
static void rses_begin_locked_property_action(
rses_property_t* prop)
{
CHK_RSES_PROP(prop);
spinlock_acquire(&prop->rses_prop_lock);
}
static void rses_end_locked_property_action(
rses_property_t* prop)
{
CHK_RSES_PROP(prop);
spinlock_release(&prop->rses_prop_lock);
}
*/
/**
* 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;
return sescmd;
}
static void mysql_sescmd_done(
mysql_sescmd_t* sescmd)
{
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(
DCB* client_dcb,
GWBUF* replybuf,
sescmd_cursor_t* scur)
{
const size_t headerlen = 4; /*< mysql packet header */
uint8_t* packet;
size_t packetlen;
mysql_sescmd_t* scmd;
ss_dassert(SPINLOCK_IS_LOCKED(&(scur->scmd_cur_rses->rses_lock)));
scmd = sescmd_cursor_get_command(scur);
CHK_DCB(client_dcb);
CHK_GWBUF(replybuf);
/**
* Walk through packets in the message and the list of session
*commands.
*/
while (scmd != NULL && replybuf != NULL)
{
if (scmd->my_sescmd_is_replied)
{
/**
* Discard heading packets if their related command is
* already replied.
*/
CHK_GWBUF(replybuf);
packet = (uint8_t *)GWBUF_DATA(replybuf);
packetlen = packet[0]+packet[1]*256+packet[2]*256*256;
replybuf = gwbuf_consume(replybuf, packetlen+headerlen);
LOGIF(LT, (skygw_log_write_flush(
LOGFILE_TRACE,
"%lu [sescmd_cursor_process_replies] cmd %p "
"is already replied. Discarded %d bytes from "
"the %s replybuffer.",
pthread_self(),
scmd,
packetlen+headerlen,
STRBETYPE(scur->scmd_cur_be_type))));
}
else
{
/** Mark the rest session commands as replied */
scmd->my_sescmd_is_replied = true;
LOGIF(LT, (skygw_log_write_flush(
LOGFILE_TRACE,
"%lu [sescmd_cursor_process_replies] Marked "
"cmd %p to as replied. Left message to %s's "
"buffer for reply.",
pthread_self(),
scmd,
STRBETYPE(scur->scmd_cur_be_type))));
}
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 sescmd_cursor_t* rses_get_sescmd_cursor(
ROUTER_CLIENT_SES* rses,
backend_type_t be_type)
{
CHK_CLIENT_RSES(rses);
ss_dassert(SPINLOCK_IS_LOCKED(&rses->rses_lock));
return &rses->rses_cursor[be_type];
}
/** router must be locked */
static bool sescmd_cursor_is_active(
sescmd_cursor_t* sescmd_cursor)
{
bool succp;
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;
ss_dassert(scur->scmd_cur_cmd != NULL);
buf = gwbuf_clone(scur->scmd_cur_cmd->my_sescmd_buf);
CHK_GWBUF(buf);
return buf;
}
/**
* 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(
ROUTER_CLIENT_SES* rses,
backend_type_t be_type)
{
DCB* dcb;
bool succp = true;
int rc = 0;
sescmd_cursor_t* scur;
dcb = rses->rses_dcb[be_type];
CHK_DCB(dcb);
CHK_CLIENT_RSES(rses);
ss_dassert(SPINLOCK_IS_LOCKED(&rses->rses_lock));
/**
* Get cursor pointer and copy of command buffer to cursor.
*/
scur = rses_get_sescmd_cursor(rses, be_type);
/** Return if there are no pending ses commands */
if (sescmd_cursor_get_command(scur) == NULL)
{
succp = false;
goto return_succp;
}
if (!sescmd_cursor_is_active(scur))
{
/** Cursor is left active when function returns. */
sescmd_cursor_set_active(scur, true);
}
LOGIF(LT, tracelog_routed_query(rses,
"execute_sescmd_in_backend",
dcb,
sescmd_cursor_clone_querybuf(scur)));
switch (scur->scmd_cur_cmd->my_sescmd_packet_type) {
case COM_CHANGE_USER:
rc = dcb->func.auth(
dcb,
NULL,
dcb->session,
sescmd_cursor_clone_querybuf(scur));
break;
case COM_QUIT:
case COM_QUERY:
case COM_INIT_DB:
default:
rc = dcb->func.write(
dcb,
sescmd_cursor_clone_querybuf(scur));
break;
}
LOGIF(LT, (skygw_log_write_flush(
LOGFILE_TRACE,
"%lu [execute_sescmd_in_backend] Routed %s cmd %p.",
pthread_self(),
STRPACKETTYPE(scur->scmd_cur_cmd->my_sescmd_packet_type),
scur->scmd_cur_cmd)));
if (rc != 1)
{
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;
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,
DCB* dcb,
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_type_t be_type;
if (rses->rses_dcb[BE_MASTER] == dcb)
{
be_type = BE_MASTER;
}
else if (rses->rses_dcb[BE_SLAVE] == dcb)
{
be_type = BE_SLAVE;
}
else
{
be_type = BE_UNDEFINED;
}
if (GWBUF_TYPE(buf) == GWBUF_TYPE_MYSQL)
{
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';
LOGIF(LT, (skygw_log_write_flush(
LOGFILE_TRACE,
"%lu [%s] %d bytes long buf, \"%s\" -> %s:%d %s dcb %p",
pthread_self(),
funcname,
buflen,
querystr,
(be_type == BE_MASTER ?
rses->rses_backend[BE_MASTER]->backend_server->name :
(be_type == BE_SLAVE ?
rses->rses_backend[BE_SLAVE]->backend_server->name :
"Target DCB is neither of the backends. This is error")),
(be_type == BE_MASTER ?
rses->rses_backend[BE_MASTER]->backend_server->port :
(be_type == BE_SLAVE ?
rses->rses_backend[BE_SLAVE]->backend_server->port :
-1)),
STRBETYPE(be_type),
dcb)));
}
}
gwbuf_free(buf);
}
/**
* Return rc, rc < 0 if router session is closed. rc == 0 if there are no
* capabilities specified, rc > 0 when there are capabilities.
*/
static uint8_t getCapabilities (
ROUTER* inst,
void* router_session)
{
ROUTER_CLIENT_SES* rses = (ROUTER_CLIENT_SES *)router_session;
uint8_t rc;
if (!rses_begin_locked_router_action(rses))
{
rc = 0xff;
goto return_rc;
}
rc = rses->rses_capabilities;
rses_end_locked_router_action(rses);
return_rc:
return rc;
}