710012ac5d
The readwritesplit now sends COM_PING queries to backend servers that have been idle for too long. The option is configured with the `connection_keepalive` parameter.
1630 lines
55 KiB
C
1630 lines
55 KiB
C
/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2019-07-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#include "readwritesplit.h"
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#include <stdio.h>
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#include <strings.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <maxscale/router.h>
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#include "rwsplit_internal.h"
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#include <maxscale/log_manager.h>
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#include <maxscale/query_classifier.h>
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#include <maxscale/dcb.h>
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#include <maxscale/spinlock.h>
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#include <maxscale/modinfo.h>
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#include <maxscale/modutil.h>
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#include <maxscale/alloc.h>
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/**
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* @file readwritesplit.c The entry points for the read/write query splitting
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* router module.
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*
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* This file contains the entry points that comprise the API to the read write
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* query splitting router. It also contains functions that are directly called
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* by the entry point functions. Some of these are used by functions in other
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* modules of the read write split router, others are used only within this
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* module.
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*
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* @verbatim
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* Revision History
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*
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* Date Who Description
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* 01/07/2013 Vilho Raatikka Initial implementation
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* 15/07/2013 Massimiliano Pinto Added clientReply from master only in case
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* of session change
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* 17/07/2013 Massimiliano Pinto clientReply is now used by mysql_backend
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* for all reply situations
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* 18/07/2013 Massimiliano Pinto routeQuery now handles COM_QUIT
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* as QUERY_TYPE_SESSION_WRITE
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* 17/07/2014 Massimiliano Pinto Server connection counter is updated in
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* closeSession
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* 09/09/2015 Martin Brampton Modify error handler
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* 25/09/2015 Martin Brampton Block callback processing when no router
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* session in the DCB
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* 03/08/2016 Martin Brampton Extract the API functions, move the rest
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*
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* @endverbatim
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*/
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/** Maximum number of slaves */
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#define MAX_SLAVE_COUNT "255"
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/*
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* The functions that implement the router module API
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*/
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static MXS_ROUTER *createInstance(SERVICE *service, char **options);
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static MXS_ROUTER_SESSION *newSession(MXS_ROUTER *instance, MXS_SESSION *session);
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static void closeSession(MXS_ROUTER *instance, MXS_ROUTER_SESSION *session);
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static void freeSession(MXS_ROUTER *instance, MXS_ROUTER_SESSION *session);
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static int routeQuery(MXS_ROUTER *instance, MXS_ROUTER_SESSION *session, GWBUF *queue);
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static void diagnostics(MXS_ROUTER *instance, DCB *dcb);
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static void clientReply(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session, GWBUF *queue,
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DCB *backend_dcb);
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static void handleError(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session,
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GWBUF *errmsgbuf, DCB *backend_dcb,
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mxs_error_action_t action, bool *succp);
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static uint64_t getCapabilities(MXS_ROUTER* instance);
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/*
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* End of the API functions; now the module structure that links to them.
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* Note that the function names are chosen to exactly match the names used in
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* the definition of ROUTER_OBJECT. This is not obligatory, but is done to
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* make it easier to track the connection between calls and functions.
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*/
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/*
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* Declaration of functions that are used only within this module, and are
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* not part of the API.
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*/
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static void free_rwsplit_instance(ROUTER_INSTANCE *router);
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static bool rwsplit_process_router_options(ROUTER_INSTANCE *router,
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char **options);
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static void handle_error_reply_client(MXS_SESSION *ses, ROUTER_CLIENT_SES *rses,
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DCB *backend_dcb, GWBUF *errmsg);
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static bool handle_error_new_connection(ROUTER_INSTANCE *inst,
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ROUTER_CLIENT_SES **rses,
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DCB *backend_dcb, GWBUF *errmsg);
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static bool have_enough_servers(ROUTER_CLIENT_SES *rses, const int min_nsrv,
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int router_nsrv, ROUTER_INSTANCE *router);
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static bool create_backends(ROUTER_CLIENT_SES *rses, backend_ref_t** dest, int* n_backend);
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/**
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* Enum values for router parameters
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*/
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static const MXS_ENUM_VALUE use_sql_variables_in_values[] =
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{
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{"all", TYPE_ALL},
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{"master", TYPE_MASTER},
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{NULL}
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};
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static const MXS_ENUM_VALUE slave_selection_criteria_values[] =
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{
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{"LEAST_GLOBAL_CONNECTIONS", LEAST_GLOBAL_CONNECTIONS},
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{"LEAST_ROUTER_CONNECTIONS", LEAST_ROUTER_CONNECTIONS},
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{"LEAST_BEHIND_MASTER", LEAST_BEHIND_MASTER},
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{"LEAST_CURRENT_OPERATIONS", LEAST_CURRENT_OPERATIONS},
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{NULL}
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};
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static const MXS_ENUM_VALUE master_failure_mode_values[] =
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{
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{"fail_instantly", RW_FAIL_INSTANTLY},
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{"fail_on_write", RW_FAIL_ON_WRITE},
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{"error_on_write", RW_ERROR_ON_WRITE},
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{NULL}
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};
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/**
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* The module entry point routine. It is this routine that
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* must return the structure that is referred to as the
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* "module object", this is a structure with the set of
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* external entry points for this module.
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*
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* @return The module object
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*/
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MXS_MODULE *MXS_CREATE_MODULE()
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{
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static MXS_ROUTER_OBJECT MyObject =
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{
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createInstance,
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newSession,
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closeSession,
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freeSession,
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routeQuery,
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diagnostics,
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clientReply,
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handleError,
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getCapabilities,
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NULL
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};
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static MXS_MODULE info =
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{
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MXS_MODULE_API_ROUTER, MXS_MODULE_GA, MXS_ROUTER_VERSION,
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"A Read/Write splitting router for enhancement read scalability",
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"V1.1.0",
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RCAP_TYPE_STMT_INPUT | RCAP_TYPE_TRANSACTION_TRACKING,
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&MyObject,
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NULL, /* Process init. */
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NULL, /* Process finish. */
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NULL, /* Thread init. */
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NULL, /* Thread finish. */
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{
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{
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"use_sql_variables_in",
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MXS_MODULE_PARAM_ENUM,
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"all",
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MXS_MODULE_OPT_NONE,
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use_sql_variables_in_values
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},
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{
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"slave_selection_criteria",
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MXS_MODULE_PARAM_ENUM,
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"LEAST_CURRENT_OPERATIONS",
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MXS_MODULE_OPT_NONE,
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slave_selection_criteria_values
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},
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{
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"master_failure_mode",
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MXS_MODULE_PARAM_ENUM,
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"fail_instantly",
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MXS_MODULE_OPT_NONE,
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master_failure_mode_values
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},
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{"max_slave_replication_lag", MXS_MODULE_PARAM_INT, "-1"},
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{"max_slave_connections", MXS_MODULE_PARAM_STRING, MAX_SLAVE_COUNT},
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{"retry_failed_reads", MXS_MODULE_PARAM_BOOL, "true"},
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{"disable_sescmd_history", MXS_MODULE_PARAM_BOOL, "true"},
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{"max_sescmd_history", MXS_MODULE_PARAM_COUNT, "0"},
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{"strict_multi_stmt", MXS_MODULE_PARAM_BOOL, "true"},
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{"master_accept_reads", MXS_MODULE_PARAM_BOOL, "false"},
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{"connection_keepalive", MXS_MODULE_PARAM_COUNT, "0"},
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{MXS_END_MODULE_PARAMS}
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}
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};
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MXS_NOTICE("Initializing statement-based read/write split router module.");
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return &info;
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}
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// TODO: Don't process parameters in readwritesplit
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static bool handle_max_slaves(ROUTER_INSTANCE *router, const char *str)
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{
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bool rval = true;
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char *endptr;
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int val = strtol(str, &endptr, 10);
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if (*endptr == '%' && *(endptr + 1) == '\0')
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{
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router->rwsplit_config.rw_max_slave_conn_percent = val;
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router->rwsplit_config.max_slave_connections = 0;
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}
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else if (*endptr == '\0')
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{
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router->rwsplit_config.max_slave_connections = val;
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router->rwsplit_config.rw_max_slave_conn_percent = 0;
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}
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else
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{
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MXS_ERROR("Invalid value for 'max_slave_connections': %s", str);
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rval = false;
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}
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return rval;
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}
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/**
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* @brief Create an instance of the read/write router (API).
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*
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* Create an instance of read/write statement router within the MaxScale. One
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* instance of the router is required for each service that is defined in the
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* configuration as using this router. One instance of the router will handle
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* multiple connections (or router sessions).
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*
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* @param service The service this router is being create for
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* @param options The options for this query router
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* @return NULL in failure, pointer to router in success.
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*/
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static MXS_ROUTER *createInstance(SERVICE *service, char **options)
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{
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ROUTER_INSTANCE *router;
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if ((router = MXS_CALLOC(1, sizeof(ROUTER_INSTANCE))) == NULL)
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{
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return NULL;
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}
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router->service = service;
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/*
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* Until we know otherwise assume we have some available slaves.
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*/
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router->available_slaves = true;
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/** By default, the client connection is closed immediately when a master
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* failure is detected */
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router->rwsplit_config.master_failure_mode = RW_FAIL_INSTANTLY;
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MXS_CONFIG_PARAMETER *params = service->svc_config_param;
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router->rwsplit_config.use_sql_variables_in = config_get_enum(params, "use_sql_variables_in",
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use_sql_variables_in_values);
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router->rwsplit_config.slave_selection_criteria = config_get_enum(params, "slave_selection_criteria",
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slave_selection_criteria_values);
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router->rwsplit_config.master_failure_mode = config_get_enum(params, "master_failure_mode",
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master_failure_mode_values);
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router->rwsplit_config.max_slave_replication_lag = config_get_integer(params, "max_slave_replication_lag");
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router->rwsplit_config.retry_failed_reads = config_get_bool(params, "retry_failed_reads");
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router->rwsplit_config.strict_multi_stmt = config_get_bool(params, "strict_multi_stmt");
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router->rwsplit_config.disable_sescmd_history = config_get_bool(params, "disable_sescmd_history");
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router->rwsplit_config.max_sescmd_history = config_get_integer(params, "max_sescmd_history");
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router->rwsplit_config.master_accept_reads = config_get_bool(params, "master_accept_reads");
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router->rwsplit_config.connection_keepalive = config_get_integer(params, "connection_keepalive");
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if (!handle_max_slaves(router, config_get_string(params, "max_slave_connections")) ||
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(options && !rwsplit_process_router_options(router, options)))
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{
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free_rwsplit_instance(router);
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return NULL;
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}
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/** These options cancel each other out */
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if (router->rwsplit_config.disable_sescmd_history &&
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router->rwsplit_config.max_sescmd_history > 0)
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{
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router->rwsplit_config.max_sescmd_history = 0;
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}
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return (MXS_ROUTER *)router;
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}
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/**
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* @brief Associate a new session with this instance of the router (API).
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*
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* The session is used to store all the data required by the router for a
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* particular client connection. The instance of the router that relates to a
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* particular service is passed as the first parameter. The second parameter is
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* the session that has been created in response to the request from a client
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* for a connection. The passed session contains generic information; this
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* function creates the session structure that holds router specific data.
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* There is often a one to one relationship between sessions and router
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* sessions, although it is possible to create configurations where a
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* connection is handled by multiple routers, one after another.
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*
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* @param instance The router instance data
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* @param session The MaxScale session (generic connection data)
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* @return Session specific data for this session, i.e. a router session
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*/
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static MXS_ROUTER_SESSION *newSession(MXS_ROUTER *router_inst, MXS_SESSION *session)
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{
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ROUTER_INSTANCE *router = (ROUTER_INSTANCE *)router_inst;
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ROUTER_CLIENT_SES *client_rses = (ROUTER_CLIENT_SES *)MXS_CALLOC(1, sizeof(ROUTER_CLIENT_SES));
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if (client_rses == NULL)
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{
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return NULL;
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}
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#if defined(SS_DEBUG)
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client_rses->rses_chk_top = CHK_NUM_ROUTER_SES;
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client_rses->rses_chk_tail = CHK_NUM_ROUTER_SES;
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#endif
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client_rses->router = router;
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client_rses->client_dcb = session->client_dcb;
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client_rses->have_tmp_tables = false;
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client_rses->forced_node = NULL;
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memcpy(&client_rses->rses_config, &router->rwsplit_config, sizeof(client_rses->rses_config));
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int router_nservers = router->service->n_dbref;
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const int min_nservers = 1; /*< hard-coded for now */
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if (!have_enough_servers(client_rses, min_nservers, router_nservers, router))
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{
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MXS_FREE(client_rses);
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return NULL;
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}
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/**
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* Create backend reference objects for this session.
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*/
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backend_ref_t *backend_ref;
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if (!create_backends(client_rses, &backend_ref, &router_nservers))
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{
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MXS_FREE(client_rses);
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return NULL;
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}
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int max_nslaves = rses_get_max_slavecount(client_rses, router_nservers);
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int max_slave_rlag = rses_get_max_replication_lag(client_rses);
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client_rses->rses_backend_ref = backend_ref;
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client_rses->rses_nbackends = router_nservers; /*< # of backend servers */
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backend_ref_t *master_ref = NULL; /*< pointer to selected master */
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if (!select_connect_backend_servers(&master_ref, backend_ref, router_nservers,
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max_nslaves, max_slave_rlag,
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client_rses->rses_config.slave_selection_criteria,
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session, router, false))
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{
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/**
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* Master and at least <min_nslaves> slaves must be found if the router is
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* in the strict mode. If sessions without master are allowed, only
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* <min_nslaves> slaves must be found.
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*/
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MXS_FREE(client_rses->rses_backend_ref);
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MXS_FREE(client_rses);
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return NULL;
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}
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/** Copy backend pointers to router session. */
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client_rses->rses_master_ref = master_ref;
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if (client_rses->rses_config.rw_max_slave_conn_percent)
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{
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int n_conn = 0;
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double pct = (double)client_rses->rses_config.rw_max_slave_conn_percent / 100.0;
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n_conn = MXS_MAX(floor((double)client_rses->rses_nbackends * pct), 1);
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client_rses->rses_config.max_slave_connections = n_conn;
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}
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router->stats.n_sessions += 1;
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return (void *)client_rses;
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}
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/**
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* @brief Close a router session (API).
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*
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* Close a session with the router, this is the mechanism by which a router
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* may cleanup data structure etc. The instance of the router that relates to
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* the relevant service is passed, along with the router session that is to
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* be closed. Typically the function is used in conjunction with freeSession
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* which will release the resources used by a router session (see below).
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*
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* @param instance The router instance data
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* @param session The router session being closed
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*/
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static void closeSession(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session)
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{
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ROUTER_CLIENT_SES *router_cli_ses = (ROUTER_CLIENT_SES *)router_session;
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CHK_CLIENT_RSES(router_cli_ses);
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if (!router_cli_ses->rses_closed)
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{
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/**
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* Mark router session as closed. @c rses_closed is checked at the start
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* of every API function to quickly stop the processing of closed sessions.
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*/
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router_cli_ses->rses_closed = true;
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for (int i = 0; i < router_cli_ses->rses_nbackends; i++)
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{
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backend_ref_t *bref = &router_cli_ses->rses_backend_ref[i];
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if (BREF_IS_IN_USE(bref))
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{
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/** This backend is in use and it needs to be closed */
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DCB *dcb = bref->bref_dcb;
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CHK_DCB(dcb);
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ss_dassert(dcb->session->state == SESSION_STATE_STOPPING);
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if (BREF_IS_WAITING_RESULT(bref))
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{
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/** This backend was executing a query when the session was closed */
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bref_clear_state(bref, BREF_WAITING_RESULT);
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}
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bref_clear_state(bref, BREF_IN_USE);
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bref_set_state(bref, BREF_CLOSED);
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RW_CHK_DCB(bref, dcb);
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/** MXS-956: This will prevent closed DCBs from being closed twice.
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* It should not happen but for currently unknown reasons, a DCB
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* gets closed twice; first in handleError and a second time here. */
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if (dcb && dcb->state == DCB_STATE_POLLING)
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{
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dcb_close(dcb);
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}
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RW_CLOSE_BREF(bref);
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/** decrease server current connection counters */
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atomic_add(&bref->ref->connections, -1);
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}
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else
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{
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ss_dassert(!BREF_IS_WAITING_RESULT(bref));
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/** This should never be true unless a backend reference is taken
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* out of use before clearing the BREF_WAITING_RESULT state */
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if (BREF_IS_WAITING_RESULT(bref))
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{
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MXS_WARNING("A closed backend was expecting a result, this should not be possible. "
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"Decrementing active operation counter for this backend.");
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bref_clear_state(bref, BREF_WAITING_RESULT);
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}
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}
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}
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}
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}
|
|
|
|
/**
|
|
* @brief Free a router session (API).
|
|
*
|
|
* When a router session has been 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(MXS_ROUTER *router_instance, MXS_ROUTER_SESSION *router_client_session)
|
|
{
|
|
ROUTER_CLIENT_SES *router_cli_ses = (ROUTER_CLIENT_SES *)router_client_session;
|
|
|
|
/**
|
|
* For each property type, walk through the list, finalize properties
|
|
* and free the allocated memory.
|
|
*/
|
|
for (int 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;
|
|
}
|
|
}
|
|
|
|
MXS_FREE(router_cli_ses->rses_backend_ref);
|
|
MXS_FREE(router_cli_ses);
|
|
return;
|
|
}
|
|
|
|
/**
|
|
* @brief Mark a backend reference as failed
|
|
*
|
|
* @param bref Backend reference to close
|
|
* @param fatal Whether the failure was fatal
|
|
*/
|
|
void close_failed_bref(backend_ref_t *bref, bool fatal)
|
|
{
|
|
if (BREF_IS_WAITING_RESULT(bref))
|
|
{
|
|
bref_clear_state(bref, BREF_WAITING_RESULT);
|
|
}
|
|
|
|
bref_clear_state(bref, BREF_QUERY_ACTIVE);
|
|
bref_clear_state(bref, BREF_IN_USE);
|
|
bref_set_state(bref, BREF_CLOSED);
|
|
|
|
if (fatal)
|
|
{
|
|
bref_set_state(bref, BREF_FATAL_FAILURE);
|
|
}
|
|
|
|
if (sescmd_cursor_is_active(&bref->bref_sescmd_cur))
|
|
{
|
|
sescmd_cursor_set_active(&bref->bref_sescmd_cur, false);
|
|
}
|
|
|
|
if (bref->bref_pending_cmd)
|
|
{
|
|
gwbuf_free(bref->bref_pending_cmd);
|
|
bref->bref_pending_cmd = NULL;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @brief The main routing entry point for a query (API)
|
|
*
|
|
* The routeQuery function will make the routing decision based on the contents
|
|
* of the instance, session and the query itself. The query always represents
|
|
* a complete MariaDB/MySQL packet because we define the RCAP_TYPE_STMT_INPUT in
|
|
* getCapabilities().
|
|
*
|
|
* @param instance Router instance
|
|
* @param router_session Router session associated with the client
|
|
* @param querybuf Buffer containing the query
|
|
* @return 1 on success, 0 on error
|
|
*/
|
|
static int routeQuery(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session, GWBUF *querybuf)
|
|
{
|
|
ROUTER_INSTANCE *inst = (ROUTER_INSTANCE *) instance;
|
|
ROUTER_CLIENT_SES *rses = (ROUTER_CLIENT_SES *) router_session;
|
|
int rval = 0;
|
|
|
|
CHK_CLIENT_RSES(rses);
|
|
|
|
if (rses->rses_closed)
|
|
{
|
|
closed_session_reply(querybuf);
|
|
}
|
|
else
|
|
{
|
|
live_session_reply(&querybuf, rses);
|
|
if (route_single_stmt(inst, rses, querybuf))
|
|
{
|
|
rval = 1;
|
|
}
|
|
}
|
|
|
|
if (querybuf != NULL)
|
|
{
|
|
gwbuf_free(querybuf);
|
|
}
|
|
|
|
return rval;
|
|
}
|
|
|
|
/**
|
|
* @brief Diagnostics routine (API)
|
|
*
|
|
* Print query router statistics to the DCB passed in
|
|
*
|
|
* @param instance The router instance
|
|
* @param dcb The DCB for diagnostic output
|
|
*/
|
|
static void diagnostics(MXS_ROUTER *instance, DCB *dcb)
|
|
{
|
|
ROUTER_INSTANCE *router = (ROUTER_INSTANCE *)instance;
|
|
char *weightby;
|
|
double master_pct = 0.0, slave_pct = 0.0, all_pct = 0.0;
|
|
|
|
dcb_printf(dcb, "\n");
|
|
dcb_printf(dcb, "\tuse_sql_variables_in: %s\n",
|
|
mxs_target_to_str(router->rwsplit_config.use_sql_variables_in));
|
|
dcb_printf(dcb, "\tslave_selection_criteria: %s\n",
|
|
select_criteria_to_str(router->rwsplit_config.slave_selection_criteria));
|
|
dcb_printf(dcb, "\tmaster_failure_mode: %s\n",
|
|
failure_mode_to_str(router->rwsplit_config.master_failure_mode));
|
|
dcb_printf(dcb, "\tmax_slave_replication_lag: %d\n",
|
|
router->rwsplit_config.max_slave_replication_lag);
|
|
dcb_printf(dcb, "\tretry_failed_reads: %s\n",
|
|
router->rwsplit_config.retry_failed_reads ? "true" : "false");
|
|
dcb_printf(dcb, "\tstrict_multi_stmt: %s\n",
|
|
router->rwsplit_config.strict_multi_stmt ? "true" : "false");
|
|
dcb_printf(dcb, "\tdisable_sescmd_history: %s\n",
|
|
router->rwsplit_config.disable_sescmd_history ? "true" : "false");
|
|
dcb_printf(dcb, "\tmax_sescmd_history: %d\n",
|
|
router->rwsplit_config.max_sescmd_history);
|
|
dcb_printf(dcb, "\tmaster_accept_reads: %s\n",
|
|
router->rwsplit_config.master_accept_reads ? "true" : "false");
|
|
dcb_printf(dcb, "\n");
|
|
|
|
if (router->stats.n_queries > 0)
|
|
{
|
|
master_pct = ((double)router->stats.n_master / (double)router->stats.n_queries) * 100.0;
|
|
slave_pct = ((double)router->stats.n_slave / (double)router->stats.n_queries) * 100.0;
|
|
all_pct = ((double)router->stats.n_all / (double)router->stats.n_queries) * 100.0;
|
|
}
|
|
|
|
dcb_printf(dcb, "\tNumber of router sessions: %d\n",
|
|
router->stats.n_sessions);
|
|
dcb_printf(dcb, "\tCurrent no. of router sessions: %d\n",
|
|
router->service->stats.n_current);
|
|
dcb_printf(dcb, "\tNumber of queries forwarded: %d\n",
|
|
router->stats.n_queries);
|
|
dcb_printf(dcb, "\tNumber of queries forwarded to master: %d (%.2f%%)\n",
|
|
router->stats.n_master, master_pct);
|
|
dcb_printf(dcb, "\tNumber of queries forwarded to slave: %d (%.2f%%)\n",
|
|
router->stats.n_slave, slave_pct);
|
|
dcb_printf(dcb, "\tNumber of queries forwarded to all: %d (%.2f%%)\n",
|
|
router->stats.n_all, all_pct);
|
|
|
|
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 (SERVER_REF *ref = router->service->dbref; ref; ref = ref->next)
|
|
{
|
|
dcb_printf(dcb, "\t\t%-20s %3.1f%% %-6d %-6d %d\n",
|
|
ref->server->unique_name, (float)ref->weight / 10,
|
|
ref->server->stats.n_current, ref->connections,
|
|
ref->server->stats.n_current_ops);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @brief Client Reply routine (API)
|
|
*
|
|
* 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(MXS_ROUTER *instance,
|
|
MXS_ROUTER_SESSION *router_session,
|
|
GWBUF *writebuf,
|
|
DCB *backend_dcb)
|
|
{
|
|
ROUTER_CLIENT_SES *router_cli_ses = (ROUTER_CLIENT_SES *)router_session;
|
|
ROUTER_INSTANCE *router_inst = (ROUTER_INSTANCE *)instance;
|
|
DCB *client_dcb = backend_dcb->session->client_dcb;
|
|
|
|
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 (router_cli_ses->rses_closed)
|
|
{
|
|
gwbuf_free(writebuf);
|
|
return;
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
*/
|
|
|
|
backend_ref_t *bref = get_bref_from_dcb(router_cli_ses, backend_dcb);
|
|
CHK_BACKEND_REF(bref);
|
|
sescmd_cursor_t *scur = &bref->bref_sescmd_cur;
|
|
|
|
/** Statement was successfully executed, free the stored statement */
|
|
session_clear_stmt(backend_dcb->session);
|
|
|
|
/**
|
|
* Active cursor means that reply is from session command
|
|
* execution.
|
|
*/
|
|
if (sescmd_cursor_is_active(scur))
|
|
{
|
|
check_session_command_reply(writebuf, scur, bref);
|
|
|
|
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.disable_sescmd_history)
|
|
{
|
|
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.max_slave_connections,
|
|
router_cli_ses->rses_config.max_slave_replication_lag,
|
|
router_cli_ses->rses_config.slave_selection_criteria,
|
|
router_cli_ses->rses_master_ref->bref_dcb->session,
|
|
router_cli_ses->router,
|
|
true);
|
|
}
|
|
}
|
|
/**
|
|
* 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.
|
|
*/
|
|
|
|
/** 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 */
|
|
MXS_SESSION_ROUTE_REPLY(backend_dcb->session, writebuf);
|
|
}
|
|
|
|
/** 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->ref->server->name, bref->ref->server->port);
|
|
|
|
succp = execute_sescmd_in_backend(bref);
|
|
|
|
if (!succp)
|
|
{
|
|
MXS_INFO("Backend %s:%d failed to execute session command.",
|
|
bref->ref->server->name, bref->ref->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);
|
|
MXS_FREE(sql);
|
|
}
|
|
else
|
|
{
|
|
MXS_ERROR("Failed to route query.");
|
|
}
|
|
}
|
|
gwbuf_free(bref->bref_pending_cmd);
|
|
bref->bref_pending_cmd = NULL;
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* @brief Get router capabilities (API)
|
|
*
|
|
* Return a bit map indicating the characteristics of this particular router.
|
|
* In this case, the only bit set indicates that the router wants to receive
|
|
* data for routing as whole SQL statements.
|
|
*
|
|
* @return RCAP_TYPE_STMT_INPUT.
|
|
*/
|
|
static uint64_t getCapabilities(MXS_ROUTER* instance)
|
|
{
|
|
return RCAP_TYPE_NONE;
|
|
}
|
|
|
|
/*
|
|
* This is the end of the API functions, and the start of functions that are
|
|
* used by the API functions and also used in other modules of the router
|
|
* code. Their prototypes are included in rwsplit_internal.h since these
|
|
* functions are not intended for use outside the read write split router.
|
|
*/
|
|
|
|
/*
|
|
* @brief Clear one or more bits in the backend reference state
|
|
*
|
|
* The router session holds details of the backend servers that are
|
|
* involved in the routing for this particular service. Each backend
|
|
* server has a state bit string, and this function (along with
|
|
* bref_set_state) is used to manage the state.
|
|
*
|
|
* @param bref The backend reference to be modified
|
|
* @param state A bit string where the 1 bits indicate bits that should
|
|
* be turned off in the bref state.
|
|
*/
|
|
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 & BREF_WAITING_RESULT))
|
|
{
|
|
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->ref->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->ref->server->name,
|
|
bref->ref->server->port);
|
|
}
|
|
}
|
|
}
|
|
|
|
bref->bref_state &= ~state;
|
|
}
|
|
|
|
/*
|
|
* @brief Set one or more bits in the backend reference state
|
|
*
|
|
* The router session holds details of the backend servers that are
|
|
* involved in the routing for this particular service. Each backend
|
|
* server has a state bit string, and this function (along with
|
|
* bref_clear_state) is used to manage the state.
|
|
*
|
|
* @param bref The backend reference to be modified
|
|
* @param state A bit string where the 1 bits indicate bits that should
|
|
* be turned on in the bref state.
|
|
*/
|
|
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 & BREF_WAITING_RESULT) == 0)
|
|
{
|
|
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->ref->server->name, bref->ref->server->port);
|
|
}
|
|
/** Increase global operation count */
|
|
prev2 = atomic_add(&bref->ref->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->ref->server->name, bref->ref->server->port);
|
|
}
|
|
}
|
|
|
|
bref->bref_state |= state;
|
|
}
|
|
|
|
/**
|
|
* @brief Free resources belonging to a property
|
|
*
|
|
* Property is freed at the end of router client session.
|
|
*
|
|
* @param prop The property whose resources are to be released
|
|
*/
|
|
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;
|
|
}
|
|
MXS_FREE(prop);
|
|
}
|
|
|
|
/**
|
|
* @brief Get count of backend servers that are slaves.
|
|
*
|
|
* 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.
|
|
*
|
|
* @param rses Router client session
|
|
* @param router_nservers The number of backend servers in total
|
|
*/
|
|
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.max_slave_connections > 0)
|
|
{
|
|
conf_max_nslaves = rses->rses_config.max_slave_connections;
|
|
}
|
|
else
|
|
{
|
|
conf_max_nslaves = (router_nservers * rses->rses_config.rw_max_slave_conn_percent) / 100;
|
|
}
|
|
max_nslaves = MXS_MIN(router_nservers - 1, MXS_MAX(1, conf_max_nslaves));
|
|
|
|
return max_nslaves;
|
|
}
|
|
|
|
/*
|
|
* @brief Get the maximum replication lag for this router
|
|
*
|
|
* @param rses Router client session
|
|
* @return Replication lag from configuration or very large number
|
|
*/
|
|
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.max_slave_replication_lag > 0)
|
|
{
|
|
conf_max_rlag = rses->rses_config.max_slave_replication_lag;
|
|
}
|
|
else
|
|
{
|
|
conf_max_rlag = ~(1 << 31);
|
|
}
|
|
|
|
return conf_max_rlag;
|
|
}
|
|
|
|
/**
|
|
* @brief Find a back end reference that matches the given DCB
|
|
*
|
|
* 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
|
|
*/
|
|
backend_ref_t *get_bref_from_dcb(ROUTER_CLIENT_SES *rses, DCB *dcb)
|
|
{
|
|
ss_dassert(dcb->dcb_role == DCB_ROLE_BACKEND_HANDLER);
|
|
CHK_DCB(dcb);
|
|
CHK_CLIENT_RSES(rses);
|
|
|
|
for (int i = 0; i < rses->rses_nbackends; i++)
|
|
{
|
|
if (rses->rses_backend_ref[i].bref_dcb == dcb)
|
|
{
|
|
return &rses->rses_backend_ref[i];
|
|
}
|
|
}
|
|
|
|
/** We should always have a valid backend reference */
|
|
ss_dassert(false);
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* @brief Process router options
|
|
*
|
|
* @param router Router instance
|
|
* @param options Router options
|
|
* @return True on success, false if a configuration error was found
|
|
*/
|
|
static bool rwsplit_process_router_options(ROUTER_INSTANCE *router,
|
|
char **options)
|
|
{
|
|
int i;
|
|
char *value;
|
|
select_criteria_t c;
|
|
|
|
if (options == NULL)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
MXS_WARNING("Router options for readwritesplit are deprecated.");
|
|
|
|
bool success = true;
|
|
|
|
for (i = 0; options[i]; i++)
|
|
{
|
|
if ((value = strchr(options[i], '=')) == NULL)
|
|
{
|
|
MXS_ERROR("Unsupported router option \"%s\" for readwritesplit router.", options[i]);
|
|
success = false;
|
|
}
|
|
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_ERROR("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.slave_selection_criteria));
|
|
success = false;
|
|
}
|
|
else
|
|
{
|
|
router->rwsplit_config.slave_selection_criteria = c;
|
|
}
|
|
}
|
|
else if (strcmp(options[i], "max_sescmd_history") == 0)
|
|
{
|
|
router->rwsplit_config.max_sescmd_history = atoi(value);
|
|
}
|
|
else if (strcmp(options[i], "disable_sescmd_history") == 0)
|
|
{
|
|
router->rwsplit_config.disable_sescmd_history = config_truth_value(value);
|
|
}
|
|
else if (strcmp(options[i], "master_accept_reads") == 0)
|
|
{
|
|
router->rwsplit_config.master_accept_reads = config_truth_value(value);
|
|
}
|
|
else if (strcmp(options[i], "strict_multi_stmt") == 0)
|
|
{
|
|
router->rwsplit_config.strict_multi_stmt = config_truth_value(value);
|
|
}
|
|
else if (strcmp(options[i], "retry_failed_reads") == 0)
|
|
{
|
|
router->rwsplit_config.retry_failed_reads = config_truth_value(value);
|
|
}
|
|
else if (strcmp(options[i], "master_failure_mode") == 0)
|
|
{
|
|
if (strcasecmp(value, "fail_instantly") == 0)
|
|
{
|
|
router->rwsplit_config.master_failure_mode = RW_FAIL_INSTANTLY;
|
|
}
|
|
else if (strcasecmp(value, "fail_on_write") == 0)
|
|
{
|
|
router->rwsplit_config.master_failure_mode = RW_FAIL_ON_WRITE;
|
|
}
|
|
else if (strcasecmp(value, "error_on_write") == 0)
|
|
{
|
|
router->rwsplit_config.master_failure_mode = RW_ERROR_ON_WRITE;
|
|
}
|
|
else
|
|
{
|
|
MXS_ERROR("Unknown value for 'master_failure_mode': %s", value);
|
|
success = false;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
MXS_ERROR("Unknown router option \"%s=%s\" for readwritesplit router.",
|
|
options[i], value);
|
|
success = false;
|
|
}
|
|
}
|
|
} /*< for */
|
|
|
|
return success;
|
|
}
|
|
|
|
/**
|
|
* @brief Router error handling routine (API)
|
|
*
|
|
* 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(MXS_ROUTER *instance,
|
|
MXS_ROUTER_SESSION *router_session,
|
|
GWBUF *errmsgbuf,
|
|
DCB *problem_dcb,
|
|
mxs_error_action_t action,
|
|
bool *succp)
|
|
{
|
|
ss_dassert(problem_dcb->dcb_role == DCB_ROLE_BACKEND_HANDLER);
|
|
ROUTER_INSTANCE *inst = (ROUTER_INSTANCE *)instance;
|
|
ROUTER_CLIENT_SES *rses = (ROUTER_CLIENT_SES *)router_session;
|
|
CHK_CLIENT_RSES(rses);
|
|
CHK_DCB(problem_dcb);
|
|
|
|
if (rses->rses_closed)
|
|
{
|
|
*succp = false;
|
|
return;
|
|
}
|
|
|
|
MXS_SESSION *session = problem_dcb->session;
|
|
ss_dassert(session);
|
|
|
|
backend_ref_t *bref = get_bref_from_dcb(rses, problem_dcb);
|
|
|
|
switch (action)
|
|
{
|
|
case ERRACT_NEW_CONNECTION:
|
|
{
|
|
/**
|
|
* If master has lost its Master status error can't be
|
|
* handled so that session could continue.
|
|
*/
|
|
if (rses->rses_master_ref && rses->rses_master_ref->bref_dcb == problem_dcb)
|
|
{
|
|
SERVER *srv = rses->rses_master_ref->ref->server;
|
|
bool can_continue = false;
|
|
|
|
if (rses->rses_config.master_failure_mode != RW_FAIL_INSTANTLY &&
|
|
(bref == NULL || !BREF_IS_WAITING_RESULT(bref)))
|
|
{
|
|
/** The failure of a master is not considered a critical
|
|
* failure as partial functionality still remains. Reads
|
|
* are allowed as long as slave servers are available
|
|
* and writes will cause an error to be returned.
|
|
*
|
|
* If we were waiting for a response from the master, we
|
|
* can't be sure whether it was executed or not. In this
|
|
* case the safest thing to do is to close the client
|
|
* connection. */
|
|
can_continue = true;
|
|
}
|
|
else if (!SERVER_IS_MASTER(srv) && !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 = can_continue;
|
|
|
|
if (bref != NULL)
|
|
{
|
|
CHK_BACKEND_REF(bref);
|
|
RW_CHK_DCB(bref, problem_dcb);
|
|
dcb_close(problem_dcb);
|
|
RW_CLOSE_BREF(bref);
|
|
close_failed_bref(bref, true);
|
|
}
|
|
else
|
|
{
|
|
MXS_ERROR("Server %s:%d lost the master status but could not locate the "
|
|
"corresponding backend ref.", srv->name, srv->port);
|
|
}
|
|
}
|
|
else if (bref)
|
|
{
|
|
/** Check whether problem_dcb is same as dcb of rses->forced_node
|
|
* and within READ ONLY transaction:
|
|
* if true reset rses->forced_node and close session
|
|
*/
|
|
if (rses->forced_node &&
|
|
(rses->forced_node->bref_dcb == problem_dcb &&
|
|
session_trx_is_read_only(problem_dcb->session)))
|
|
{
|
|
MXS_ERROR("forced_node SLAVE %s in opened READ ONLY transaction has failed:"
|
|
" closing session",
|
|
problem_dcb->server->unique_name);
|
|
|
|
rses->forced_node = NULL;
|
|
*succp = false;
|
|
break;
|
|
}
|
|
|
|
/** We should reconnect only if we find a backend for this
|
|
* DCB. If this DCB is an older DCB that has been closed,
|
|
* we can ignore it. */
|
|
*succp = handle_error_new_connection(inst, &rses, problem_dcb, errmsgbuf);
|
|
}
|
|
|
|
if (bref)
|
|
{
|
|
/** This is a valid DCB for a backend ref */
|
|
if (BREF_IS_IN_USE(bref) && bref->bref_dcb == problem_dcb)
|
|
{
|
|
ss_dassert(false);
|
|
MXS_ERROR("Backend '%s' is still in use and points to the problem DCB.",
|
|
bref->ref->server->unique_name);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
const char *remote = problem_dcb->state == DCB_STATE_POLLING &&
|
|
problem_dcb->server ? problem_dcb->server->unique_name : "CLOSED";
|
|
|
|
MXS_ERROR("DCB connected to '%s' is not in use by the router "
|
|
"session, not closing it. DCB is in state '%s'",
|
|
remote, STRDCBSTATE(problem_dcb->state));
|
|
}
|
|
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:
|
|
ss_dassert(!true);
|
|
*succp = false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @brief Handle an error reply for a client
|
|
*
|
|
* @param ses Session
|
|
* @param rses Router session
|
|
* @param backend_dcb DCB for the backend server that has failed
|
|
* @param errmsg GWBUF containing the error message
|
|
*/
|
|
static void handle_error_reply_client(MXS_SESSION *ses, ROUTER_CLIENT_SES *rses,
|
|
DCB *backend_dcb, GWBUF *errmsg)
|
|
{
|
|
mxs_session_state_t sesstate;
|
|
DCB *client_dcb;
|
|
backend_ref_t *bref;
|
|
|
|
sesstate = ses->state;
|
|
client_dcb = ses->client_dcb;
|
|
|
|
if ((bref = get_bref_from_dcb(rses, backend_dcb)) != NULL)
|
|
{
|
|
CHK_BACKEND_REF(bref);
|
|
|
|
if (BREF_IS_IN_USE(bref))
|
|
{
|
|
close_failed_bref(bref, false);
|
|
RW_CHK_DCB(bref, backend_dcb);
|
|
dcb_close(backend_dcb);
|
|
RW_CLOSE_BREF(bref);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
// All dcbs should be associated with a backend reference.
|
|
ss_dassert(!true);
|
|
}
|
|
|
|
if (sesstate == SESSION_STATE_ROUTER_READY)
|
|
{
|
|
CHK_DCB(client_dcb);
|
|
client_dcb->func.write(client_dcb, gwbuf_clone(errmsg));
|
|
}
|
|
}
|
|
|
|
static bool reroute_stored_statement(ROUTER_CLIENT_SES *rses, backend_ref_t *old, GWBUF *stored)
|
|
{
|
|
bool success = false;
|
|
|
|
if (!session_trx_is_active(rses->client_dcb->session))
|
|
{
|
|
/**
|
|
* Only try to retry the read if autocommit is enabled and we are
|
|
* outside of a transaction
|
|
*/
|
|
for (int i = 0; i < rses->rses_nbackends; i++)
|
|
{
|
|
backend_ref_t *bref = &rses->rses_backend_ref[i];
|
|
|
|
if (BREF_IS_IN_USE(bref) && bref != old &&
|
|
!SERVER_IS_MASTER(bref->ref->server) &&
|
|
SERVER_IS_SLAVE(bref->ref->server))
|
|
{
|
|
/** Found a valid candidate; a non-master slave that's in use */
|
|
if (bref->bref_dcb->func.write(bref->bref_dcb, stored))
|
|
{
|
|
MXS_INFO("Retrying failed read at '%s'.", bref->ref->server->unique_name);
|
|
success = true;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!success && rses->rses_master_ref && BREF_IS_IN_USE(rses->rses_master_ref))
|
|
{
|
|
/**
|
|
* Either we failed to write to the slave or no valid slave was found.
|
|
* Try to retry the read on the master.
|
|
*/
|
|
backend_ref_t *bref = rses->rses_master_ref;
|
|
|
|
if (bref->bref_dcb->func.write(bref->bref_dcb, stored))
|
|
{
|
|
MXS_INFO("Retrying failed read at '%s'.", bref->ref->server->unique_name);
|
|
success = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
return success;
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
MXS_SESSION *ses;
|
|
int max_nslaves;
|
|
int max_slave_rlag;
|
|
backend_ref_t *bref;
|
|
bool succp;
|
|
|
|
myrses = *rses;
|
|
|
|
ses = backend_dcb->session;
|
|
CHK_SESSION(ses);
|
|
|
|
/**
|
|
* If bref == NULL it has been replaced already with another one.
|
|
*
|
|
* NOTE: This can never happen.
|
|
*/
|
|
if ((bref = get_bref_from_dcb(myrses, backend_dcb)) == NULL)
|
|
{
|
|
return true;
|
|
}
|
|
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))
|
|
{
|
|
GWBUF *stored;
|
|
const SERVER *target;
|
|
|
|
if (!session_take_stmt(backend_dcb->session, &stored, &target) ||
|
|
target != bref->ref->server ||
|
|
!reroute_stored_statement(*rses, bref, stored))
|
|
{
|
|
/**
|
|
* We failed to route the stored statement or no statement was
|
|
* stored for this server. Either way we can safely free the buffer.
|
|
*/
|
|
gwbuf_free(stored);
|
|
|
|
DCB *client_dcb = ses->client_dcb;
|
|
client_dcb->func.write(client_dcb, gwbuf_clone(errmsg));
|
|
}
|
|
}
|
|
|
|
RW_CHK_DCB(bref, backend_dcb);
|
|
dcb_close(backend_dcb);
|
|
RW_CLOSE_BREF(bref);
|
|
close_failed_bref(bref, false);
|
|
max_nslaves = rses_get_max_slavecount(myrses, myrses->rses_nbackends);
|
|
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.disable_sescmd_history)
|
|
{
|
|
succp = have_enough_servers(myrses, 1, myrses->rses_nbackends, inst) ? true : false;
|
|
}
|
|
else
|
|
{
|
|
succp = select_connect_backend_servers(&myrses->rses_master_ref,
|
|
myrses->rses_backend_ref,
|
|
myrses->rses_nbackends,
|
|
max_nslaves, max_slave_rlag,
|
|
myrses->rses_config.slave_selection_criteria,
|
|
ses, inst, true);
|
|
}
|
|
|
|
return succp;
|
|
}
|
|
|
|
/**
|
|
* @brief Calculate whether we have enough servers to route a query
|
|
*
|
|
* @param p_rses Router session
|
|
* @param min_nsrv Minimum number of servers that is sufficient
|
|
* @param nsrv Actual number of servers
|
|
* @param router Router instance
|
|
*
|
|
* @return bool - whether enough, side effect is error logging
|
|
*/
|
|
static bool have_enough_servers(ROUTER_CLIENT_SES *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 ||
|
|
MXS_MAX((rses)->rses_config.max_slave_connections,
|
|
(router_nsrv * (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 = (rses)->rses_config.rw_max_slave_conn_percent / 100;
|
|
int nservers = router_nsrv * pct;
|
|
|
|
if ((rses)->rses_config.max_slave_connections < 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,
|
|
(rses)->rses_config.max_slave_connections, 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,
|
|
(rses)->rses_config.rw_max_slave_conn_percent, dbgpct);
|
|
}
|
|
}
|
|
succp = false;
|
|
}
|
|
else
|
|
{
|
|
succp = true;
|
|
}
|
|
return succp;
|
|
}
|
|
|
|
/*
|
|
* @brief Release resources when createInstance fails to complete
|
|
*
|
|
* Internal to createInstance
|
|
*
|
|
* @param router Router instance
|
|
*
|
|
*/
|
|
static void free_rwsplit_instance(ROUTER_INSTANCE *router)
|
|
{
|
|
if (router)
|
|
{
|
|
MXS_FREE(router);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* @brief Create backend server references
|
|
*
|
|
* This creates a new set of backend references for the client session. Currently
|
|
* this is only used on startup but it could be used to dynamically change the
|
|
* set of used servers.
|
|
*
|
|
* @param rses Client router session
|
|
* @param dest Destination where the array of backens is stored
|
|
* @param n_backend Number of items in the array
|
|
* @return True on success, false on error
|
|
*/
|
|
static bool create_backends(ROUTER_CLIENT_SES *rses, backend_ref_t** dest, int* n_backend)
|
|
{
|
|
backend_ref_t *backend_ref = (backend_ref_t *)MXS_CALLOC(1, *n_backend * sizeof(backend_ref_t));
|
|
|
|
if (backend_ref == NULL)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
int i = 0;
|
|
|
|
for (SERVER_REF *sref = rses->router->service->dbref; sref && i < *n_backend; sref = sref->next)
|
|
{
|
|
if (sref->active)
|
|
{
|
|
#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].ref = sref;
|
|
/** store pointers to sescmd list to both cursors */
|
|
backend_ref[i].bref_sescmd_cur.scmd_cur_rses = rses;
|
|
backend_ref[i].bref_sescmd_cur.scmd_cur_active = false;
|
|
backend_ref[i].bref_sescmd_cur.scmd_cur_ptr_property =
|
|
&rses->rses_properties[RSES_PROP_TYPE_SESCMD];
|
|
backend_ref[i].bref_sescmd_cur.scmd_cur_cmd = NULL;
|
|
i++;
|
|
}
|
|
}
|
|
|
|
if (i < *n_backend)
|
|
{
|
|
MXS_INFO("The service reported %d servers but only took %d into use.", *n_backend, i);
|
|
*n_backend = i;
|
|
}
|
|
|
|
*dest = backend_ref;
|
|
return true;
|
|
}
|