e62be5034a
The `user`, `password`, `version_string` and `weightby` values should be allocated as a part of the service structure. This allows them to be modified at runtime without having to worry about memory allocation problems. Although this removes the problem of reallocation, it still does not make the updating of the strings thread-safe. This can cause invalid values to be read from the service strings.
839 lines
26 KiB
C
839 lines
26 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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/**
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* @file readconnroute.c - Read Connection Load Balancing Query Router
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*
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* This is the implementation of a simple query router that balances
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* read connections. It assumes the service is configured with a set
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* of slaves and that the application clients already split read and write
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* queries. It offers a service to balance the client read connections
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* over this set of slave servers. It does this once only, at the time
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* the connection is made. It chooses the server that currently has the least
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* number of connections by keeping a count for each server of how
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* many connections the query router has made to the server.
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*
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* When two servers have the same number of current connections the one with
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* the least number of connections since startup will be used.
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*
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* The router may also have options associated to it that will limit the
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* choice of backend server. Currently two options are supported, the "master"
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* option will cause the router to only connect to servers marked as masters
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* and the "slave" option will limit connections to routers that are marked
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* as slaves. If neither option is specified the router will connect to either
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* masters or slaves.
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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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* 14/06/2013 Mark Riddoch Initial implementation
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* 25/06/2013 Mark Riddoch Addition of checks for current server state
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* 26/06/2013 Mark Riddoch Use server with least connections since
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* startup if the number of current
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* connections is the same for two servers
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* Addition of master and slave options
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* 27/06/2013 Vilho Raatikka Added skygw_log_write command as an example
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* and necessary headers.
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* 17/07/2013 Massimiliano Pinto Added clientReply routine:
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* called by backend server to send data to client
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* Included maxscale/protocol/mysql.h
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* with macros and MySQL commands with MYSQL_ prefix
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* avoiding any conflict with the standard ones
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* in mysql.h
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* 22/07/2013 Mark Riddoch Addition of joined router option for Galera
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* clusters
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* 31/07/2013 Massimiliano Pinto Added a check for candidate server, if NULL return
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* 12/08/2013 Mark Riddoch Log unsupported router options
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* 04/09/2013 Massimiliano Pinto Added client NULL check in clientReply
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* 22/10/2013 Massimiliano Pinto errorReply called from backend, for client error reply
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* or take different actions such as open a new backend connection
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* 20/02/2014 Massimiliano Pinto If router_options=slave, route traffic to master if no slaves available
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* 06/03/2014 Massimiliano Pinto Server connection counter is now updated in closeSession
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* 24/06/2014 Massimiliano Pinto New rules for selecting the Master server
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* 27/06/2014 Mark Riddoch Addition of server weighting
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* 11/06/2015 Martin Brampton Remove decrement n_current (moved to dcb.c)
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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 session in the DCB
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* 09/11/2015 Martin Brampton Modified routeQuery - must free "queue" regardless of outcome
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*
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* @endverbatim
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*/
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#include "readconnection.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <signal.h>
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#include <maxscale/alloc.h>
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#include <maxscale/server.h>
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#include <maxscale/router.h>
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#include <maxscale/atomic.h>
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#include <maxscale/spinlock.h>
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#include <maxscale/dcb.h>
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#include <maxscale/modinfo.h>
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#include <maxscale/log_manager.h>
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#include <maxscale/protocol/mysql.h>
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#include <maxscale/modutil.h>
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/* The router entry points */
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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 *router_session);
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static void freeSession(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session);
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static int routeQuery(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session, GWBUF *queue);
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static void diagnostics(MXS_ROUTER *instance, DCB *dcb);
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static json_t* diagnostics_json(const MXS_ROUTER *instance);
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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, GWBUF *errbuf,
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DCB *problem_dcb, mxs_error_action_t action, bool *succp);
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static uint64_t getCapabilities(MXS_ROUTER* instance);
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static bool rses_begin_locked_router_action(ROUTER_CLIENT_SES* rses);
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static void rses_end_locked_router_action(ROUTER_CLIENT_SES* rses);
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static SERVER_REF *get_root_master(SERVER_REF *servers);
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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 populate 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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MXS_NOTICE("Initialise readconnroute router 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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|
diagnostics_json,
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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,
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MXS_MODULE_GA,
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MXS_ROUTER_VERSION,
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"A connection based router to load balance based on connections",
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"V1.1.0",
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MXS_NO_MODULE_CAPABILITIES,
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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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{MXS_END_MODULE_PARAMS}
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}
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};
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return &info;
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}
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static inline void free_readconn_instance(ROUTER_INSTANCE *router)
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{
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if (router)
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|
{
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MXS_FREE(router);
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}
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}
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/**
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* Create an instance of the router for a particular service
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* within the gateway.
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*
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* @param service The service this router is being create for
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* @param options An array of options for this query router
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*
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* @return The instance data for this new instance
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|
*/
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static MXS_ROUTER *
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createInstance(SERVICE *service, char **options)
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|
{
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ROUTER_INSTANCE *inst;
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SERVER_REF *sref;
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int i, n;
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|
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if ((inst = 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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inst->service = service;
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spinlock_init(&inst->lock);
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|
|
|
/*
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* Process the options
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|
*/
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bool error = false;
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inst->bitmask = 0;
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inst->bitvalue = 0;
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if (options)
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{
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for (i = 0; options[i]; i++)
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{
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if (!strcasecmp(options[i], "master"))
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{
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inst->bitmask |= (SERVER_MASTER | SERVER_SLAVE);
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inst->bitvalue |= SERVER_MASTER;
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}
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else if (!strcasecmp(options[i], "slave"))
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{
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inst->bitmask |= (SERVER_MASTER | SERVER_SLAVE);
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inst->bitvalue |= SERVER_SLAVE;
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}
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else if (!strcasecmp(options[i], "running"))
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{
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inst->bitmask |= (SERVER_RUNNING);
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|
inst->bitvalue |= SERVER_RUNNING;
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|
}
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else if (!strcasecmp(options[i], "synced"))
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{
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inst->bitmask |= (SERVER_JOINED);
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inst->bitvalue |= SERVER_JOINED;
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|
}
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else if (!strcasecmp(options[i], "ndb"))
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{
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inst->bitmask |= (SERVER_NDB);
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inst->bitvalue |= SERVER_NDB;
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}
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else
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{
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MXS_WARNING("Unsupported router "
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|
"option \'%s\' for readconnroute. "
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|
"Expected router options are "
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|
"[slave|master|synced|ndb|running]",
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|
options[i]);
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error = true;
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}
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}
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}
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|
if (error)
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{
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|
free_readconn_instance(inst);
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return NULL;
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|
}
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|
|
|
if (inst->bitmask == 0 && inst->bitvalue == 0)
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{
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|
/** No parameters given, use RUNNING as a valid server */
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|
inst->bitmask |= (SERVER_RUNNING);
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|
inst->bitvalue |= SERVER_RUNNING;
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|
}
|
|
/*
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|
* We have completed the creation of the instance data, so now
|
|
* insert this router instance into the linked list of routers
|
|
* that have been created with this module.
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|
*/
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|
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|
return (MXS_ROUTER *) inst;
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|
}
|
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|
|
/**
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|
* Associate a new session with this instance of the router.
|
|
*
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|
* @param instance The router instance data
|
|
* @param session The session itself
|
|
* @return Session specific data for this session
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|
*/
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|
static MXS_ROUTER_SESSION *
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|
newSession(MXS_ROUTER *instance, MXS_SESSION *session)
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|
{
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|
ROUTER_INSTANCE *inst = (ROUTER_INSTANCE *) instance;
|
|
ROUTER_CLIENT_SES *client_rses;
|
|
SERVER_REF *candidate = NULL;
|
|
int i;
|
|
SERVER_REF *master_host = NULL;
|
|
|
|
MXS_DEBUG("%lu [newSession] new router session with session "
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|
"%p, and inst %p.",
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pthread_self(),
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session,
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inst);
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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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|
}
|
|
|
|
#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->client_dcb = session->client_dcb;
|
|
|
|
/**
|
|
* Find the Master host from available servers
|
|
*/
|
|
master_host = get_root_master(inst->service->dbref);
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
|
|
/*
|
|
* Loop over all the servers and find any that have fewer connections
|
|
* than the candidate server.
|
|
*
|
|
* If a server has less connections than the current candidate we mark this
|
|
* as the new candidate to connect to.
|
|
*
|
|
* 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.
|
|
*/
|
|
for (SERVER_REF *ref = inst->service->dbref; ref; ref = ref->next)
|
|
{
|
|
if (!SERVER_REF_IS_ACTIVE(ref) || SERVER_IN_MAINT(ref->server) || ref->weight == 0)
|
|
{
|
|
continue;
|
|
}
|
|
else
|
|
{
|
|
MXS_DEBUG("%lu [newSession] Examine server in port %d with "
|
|
"%d connections. Status is %s, "
|
|
"inst->bitvalue is %d",
|
|
pthread_self(),
|
|
ref->server->port,
|
|
ref->connections,
|
|
STRSRVSTATUS(ref->server),
|
|
inst->bitmask);
|
|
}
|
|
|
|
/* Check server status bits against bitvalue from router_options */
|
|
if (ref && SERVER_IS_RUNNING(ref->server) &&
|
|
(ref->server->status & inst->bitmask & inst->bitvalue))
|
|
{
|
|
if (master_host)
|
|
{
|
|
if (ref == master_host && (inst->bitvalue & SERVER_SLAVE))
|
|
{
|
|
/* Skip root master here, as it could also be slave of an external server that
|
|
* is not in the configuration. Intermediate masters (Relay Servers) are also
|
|
* slave and will be selected as Slave(s)
|
|
*/
|
|
|
|
continue;
|
|
}
|
|
if (ref == master_host && (inst->bitvalue & SERVER_MASTER))
|
|
{
|
|
/* If option is "master" return only the root Master as there could be
|
|
* intermediate masters (Relay Servers) and they must not be selected.
|
|
*/
|
|
|
|
candidate = master_host;
|
|
break;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* Master_host is NULL, no master server. If requested router_option is 'master'
|
|
* candidate wll be NULL.
|
|
*/
|
|
if (inst->bitvalue & SERVER_MASTER)
|
|
{
|
|
candidate = NULL;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* If no candidate set, set first running server as our initial candidate server */
|
|
if (candidate == NULL)
|
|
{
|
|
candidate = ref;
|
|
}
|
|
else if (((ref->connections + 1) * 1000) / ref->weight <
|
|
((candidate->connections + 1) * 1000) / candidate->weight)
|
|
{
|
|
/* This running server has fewer connections, set it as a new candidate */
|
|
candidate = ref;
|
|
}
|
|
else if (((ref->connections + 1) * 1000) / ref->weight ==
|
|
((candidate->connections + 1) * 1000) / candidate->weight &&
|
|
ref->server->stats.n_connections < candidate->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*/
|
|
candidate = ref;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* If we haven't found a proper candidate yet but a master server is available, we'll pick that
|
|
* with the assumption that it is "better" than a slave.
|
|
*/
|
|
if (!candidate)
|
|
{
|
|
if (master_host)
|
|
{
|
|
candidate = master_host;
|
|
}
|
|
else
|
|
{
|
|
MXS_ERROR("Failed to create new routing session. Couldn't find eligible"
|
|
" candidate server. Freeing allocated resources.");
|
|
MXS_FREE(client_rses);
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We now have the server with the least connections.
|
|
* Bump the connection count for this server
|
|
*/
|
|
client_rses->backend = candidate;
|
|
|
|
/** Open the backend connection */
|
|
client_rses->backend_dcb = dcb_connect(candidate->server, session,
|
|
candidate->server->protocol);
|
|
|
|
if (client_rses->backend_dcb == NULL)
|
|
{
|
|
/** The failure is reported in dcb_connect() */
|
|
MXS_FREE(client_rses);
|
|
return NULL;
|
|
}
|
|
|
|
atomic_add(&candidate->connections, 1);
|
|
|
|
inst->stats.n_sessions++;
|
|
|
|
CHK_CLIENT_RSES(client_rses);
|
|
|
|
MXS_INFO("New session for server %s. Connections : %d",
|
|
candidate->server->unique_name, candidate->connections);
|
|
|
|
return (void *) client_rses;
|
|
}
|
|
|
|
/**
|
|
* @node Unlink from backend server, unlink from router's connection list,
|
|
* and free memory of a router client session.
|
|
*
|
|
* Parameters:
|
|
* @param router - <usage>
|
|
* <description>
|
|
*
|
|
* @param router_cli_ses - <usage>
|
|
* <description>
|
|
*
|
|
* @return void
|
|
*
|
|
*
|
|
* @details (write detailed description here)
|
|
*
|
|
*/
|
|
static void freeSession(MXS_ROUTER* router_instance, MXS_ROUTER_SESSION* router_client_ses)
|
|
{
|
|
ROUTER_INSTANCE* router = (ROUTER_INSTANCE *) router_instance;
|
|
ROUTER_CLIENT_SES* router_cli_ses = (ROUTER_CLIENT_SES *) router_client_ses;
|
|
|
|
ss_debug(int prev_val = ) atomic_add(&router_cli_ses->backend->connections, -1);
|
|
ss_dassert(prev_val > 0);
|
|
|
|
MXS_FREE(router_cli_ses);
|
|
}
|
|
|
|
/**
|
|
* 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 router_session The session being closed
|
|
*/
|
|
static void
|
|
closeSession(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session)
|
|
{
|
|
ROUTER_CLIENT_SES *router_cli_ses = (ROUTER_CLIENT_SES *) router_session;
|
|
DCB* backend_dcb;
|
|
|
|
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 counter */
|
|
|
|
backend_dcb = router_cli_ses->backend_dcb;
|
|
router_cli_ses->backend_dcb = NULL;
|
|
router_cli_ses->rses_closed = true;
|
|
/** Unlock */
|
|
rses_end_locked_router_action(router_cli_ses);
|
|
|
|
/**
|
|
* Close the backend server connection
|
|
*/
|
|
if (backend_dcb != NULL)
|
|
{
|
|
CHK_DCB(backend_dcb);
|
|
dcb_close(backend_dcb);
|
|
}
|
|
}
|
|
}
|
|
|
|
/** Log routing failure due to closed session */
|
|
static void log_closed_session(mysql_server_cmd_t mysql_command, bool is_closed,
|
|
SERVER_REF *ref)
|
|
{
|
|
char msg[MAX_SERVER_NAME_LEN + 200] = ""; // Extra space for message
|
|
|
|
if (is_closed)
|
|
{
|
|
sprintf(msg, "Session is closed.");
|
|
}
|
|
else if (SERVER_IS_DOWN(ref->server))
|
|
{
|
|
sprintf(msg, "Server '%s' is down.", ref->server->unique_name);
|
|
}
|
|
else if (!SERVER_REF_IS_ACTIVE(ref))
|
|
{
|
|
sprintf(msg, "Server '%s' was removed from the service.", ref->server->unique_name);
|
|
}
|
|
else if (SERVER_IN_MAINT(ref->server))
|
|
{
|
|
sprintf(msg, "Server '%s' is in maintenance.", ref->server->unique_name);
|
|
}
|
|
|
|
MXS_ERROR("Failed to route MySQL command %d to backend server. %s",
|
|
mysql_command, msg);
|
|
}
|
|
|
|
/**
|
|
* We have data from the client, we must route it to the backend.
|
|
* This is simply a case of sending it to the connection that was
|
|
* chosen when we started the client session.
|
|
*
|
|
* @param instance The router instance
|
|
* @param router_session The router session returned from the newSession call
|
|
* @param queue The queue of data buffers to route
|
|
* @return if succeed 1, otherwise 0
|
|
*/
|
|
static int
|
|
routeQuery(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session, GWBUF *queue)
|
|
{
|
|
ROUTER_INSTANCE *inst = (ROUTER_INSTANCE *) instance;
|
|
ROUTER_CLIENT_SES *router_cli_ses = (ROUTER_CLIENT_SES *) router_session;
|
|
int rc = 0;
|
|
DCB* backend_dcb;
|
|
MySQLProtocol *proto = (MySQLProtocol*)router_cli_ses->client_dcb->protocol;
|
|
mysql_server_cmd_t mysql_command = proto->current_command;
|
|
bool rses_is_closed;
|
|
|
|
inst->stats.n_queries++;
|
|
|
|
/** 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)
|
|
{
|
|
backend_dcb = router_cli_ses->backend_dcb;
|
|
/** unlock */
|
|
rses_end_locked_router_action(router_cli_ses);
|
|
}
|
|
|
|
if (rses_is_closed || backend_dcb == NULL ||
|
|
!SERVER_REF_IS_ACTIVE(router_cli_ses->backend) ||
|
|
!SERVER_IS_RUNNING(router_cli_ses->backend->server))
|
|
{
|
|
log_closed_session(mysql_command, rses_is_closed, router_cli_ses->backend);
|
|
gwbuf_free(queue);
|
|
goto return_rc;
|
|
|
|
}
|
|
|
|
char* trc = NULL;
|
|
|
|
switch (mysql_command)
|
|
{
|
|
case MYSQL_COM_CHANGE_USER:
|
|
rc = backend_dcb->func.auth(backend_dcb, NULL, backend_dcb->session,
|
|
queue);
|
|
break;
|
|
case MYSQL_COM_QUERY:
|
|
if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_INFO))
|
|
{
|
|
trc = modutil_get_SQL(queue);
|
|
}
|
|
default:
|
|
rc = backend_dcb->func.write(backend_dcb, queue);
|
|
break;
|
|
}
|
|
|
|
MXS_INFO("Routed [%s] to '%s'%s%s",
|
|
STRPACKETTYPE(mysql_command),
|
|
backend_dcb->server->unique_name,
|
|
trc ? ": " : ".",
|
|
trc ? trc : "");
|
|
MXS_FREE(trc);
|
|
|
|
return_rc:
|
|
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* Display router diagnostics
|
|
*
|
|
* @param instance Instance of the router
|
|
* @param dcb DCB to send diagnostics to
|
|
*/
|
|
static void
|
|
diagnostics(MXS_ROUTER *router, DCB *dcb)
|
|
{
|
|
ROUTER_INSTANCE *router_inst = (ROUTER_INSTANCE *) router;
|
|
const char *weightby = serviceGetWeightingParameter(router_inst->service);
|
|
|
|
dcb_printf(dcb, "\tNumber of router sessions: %d\n",
|
|
router_inst->stats.n_sessions);
|
|
dcb_printf(dcb, "\tCurrent no. of router sessions: %d\n",
|
|
router_inst->service->stats.n_current);
|
|
dcb_printf(dcb, "\tNumber of queries forwarded: %d\n",
|
|
router_inst->stats.n_queries);
|
|
if (*weightby)
|
|
{
|
|
dcb_printf(dcb, "\tConnection distribution based on %s "
|
|
"server parameter.\n",
|
|
weightby);
|
|
dcb_printf(dcb,
|
|
"\t\tServer Target %% Connections\n");
|
|
for (SERVER_REF *ref = router_inst->service->dbref; ref; ref = ref->next)
|
|
{
|
|
dcb_printf(dcb, "\t\t%-20s %3.1f%% %d\n",
|
|
ref->server->unique_name,
|
|
(float) ref->weight / 10,
|
|
ref->connections);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Display router diagnostics
|
|
*
|
|
* @param instance Instance of the router
|
|
* @param dcb DCB to send diagnostics to
|
|
*/
|
|
static json_t* diagnostics_json(const MXS_ROUTER *router)
|
|
{
|
|
ROUTER_INSTANCE *router_inst = (ROUTER_INSTANCE *)router;
|
|
json_t* rval = json_object();
|
|
|
|
json_object_set_new(rval, "connections", json_integer(router_inst->stats.n_sessions));
|
|
json_object_set_new(rval, "current_connections", json_integer(router_inst->service->stats.n_current));
|
|
json_object_set_new(rval, "queries", json_integer(router_inst->stats.n_queries));
|
|
|
|
const char *weightby = serviceGetWeightingParameter(router_inst->service);
|
|
|
|
if (*weightby)
|
|
{
|
|
json_object_set_new(rval, "weightby", json_string(weightby));
|
|
}
|
|
|
|
return rval;
|
|
}
|
|
|
|
/**
|
|
* Client Reply routine
|
|
*
|
|
* The routine will reply to client data from backend server
|
|
*
|
|
* @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 *queue, DCB *backend_dcb)
|
|
{
|
|
ss_dassert(backend_dcb->session->client_dcb != NULL);
|
|
MXS_SESSION_ROUTE_REPLY(backend_dcb->session, queue);
|
|
}
|
|
|
|
/**
|
|
* Error Handler routine
|
|
*
|
|
* The routine will handle errors that occurred in writes.
|
|
*
|
|
* @param instance The router instance
|
|
* @param router_session The router session
|
|
* @param message The error message to reply
|
|
* @param problem_dcb The DCB related to the error
|
|
* @param action The action: ERRACT_NEW_CONNECTION or ERRACT_REPLY_CLIENT
|
|
* @param succp Result of action: true if router can continue
|
|
*
|
|
*/
|
|
static void handleError(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session, GWBUF *errbuf,
|
|
DCB *problem_dcb, mxs_error_action_t action, bool *succp)
|
|
|
|
{
|
|
ss_dassert(problem_dcb->dcb_role == DCB_ROLE_BACKEND_HANDLER);
|
|
DCB *client_dcb;
|
|
MXS_SESSION *session = problem_dcb->session;
|
|
mxs_session_state_t sesstate;
|
|
ROUTER_CLIENT_SES *router_cli_ses = (ROUTER_CLIENT_SES *) router_session;
|
|
|
|
sesstate = session->state;
|
|
client_dcb = session->client_dcb;
|
|
|
|
if (sesstate == SESSION_STATE_ROUTER_READY)
|
|
{
|
|
CHK_DCB(client_dcb);
|
|
|
|
client_dcb->func.write(client_dcb, gwbuf_clone(errbuf));
|
|
}
|
|
|
|
if (router_cli_ses && problem_dcb == router_cli_ses->backend_dcb)
|
|
{
|
|
router_cli_ses->backend_dcb = NULL;
|
|
dcb_close(problem_dcb);
|
|
}
|
|
|
|
/** false because connection is not available anymore */
|
|
*succp = false;
|
|
}
|
|
|
|
/** 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:
|
|
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);
|
|
}
|
|
|
|
static uint64_t getCapabilities(MXS_ROUTER* instance)
|
|
{
|
|
return RCAP_TYPE_NONE;
|
|
}
|
|
|
|
/********************************
|
|
* This routine returns the root master server from MySQL replication tree
|
|
* Get the root Master rule:
|
|
*
|
|
* find server with the lowest replication depth level
|
|
* and the SERVER_MASTER bitval
|
|
* Servers are checked even if they are in 'maintenance'
|
|
*
|
|
* @param servers The list of servers
|
|
* @return The Master found
|
|
*
|
|
*/
|
|
|
|
static SERVER_REF *get_root_master(SERVER_REF *servers)
|
|
{
|
|
int i = 0;
|
|
SERVER_REF *master_host = NULL;
|
|
|
|
for (SERVER_REF *ref = servers; ref; ref = ref->next)
|
|
{
|
|
if (ref->active && SERVER_IS_MASTER(ref->server))
|
|
{
|
|
if (master_host == NULL)
|
|
{
|
|
master_host = ref;
|
|
}
|
|
else if (ref->server->depth < master_host->server->depth ||
|
|
(ref->server->depth == master_host->server->depth &&
|
|
ref->weight > master_host->weight))
|
|
{
|
|
/**
|
|
* This master has a lower depth than the candidate master or
|
|
* the depths are equal but this master has a higher weight
|
|
*/
|
|
master_host = ref;
|
|
}
|
|
}
|
|
}
|
|
return master_host;
|
|
}
|