928 lines
27 KiB
C
928 lines
27 KiB
C
/*
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* This file is distributed as part of the SkySQL Gateway. It is free
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* software: you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation,
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* version 2.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Copyright SkySQL Ab 2013
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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 mysql_client_server_protocol.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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*
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* @endverbatim
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*/
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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 <service.h>
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#include <server.h>
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#include <router.h>
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#include <atomic.h>
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#include <spinlock.h>
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#include <readconnection.h>
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#include <dcb.h>
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#include <spinlock.h>
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#include <modinfo.h>
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#include <skygw_types.h>
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#include <skygw_utils.h>
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#include <log_manager.h>
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#include <mysql_client_server_protocol.h>
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extern int lm_enabled_logfiles_bitmask;
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MODULE_INFO info = {
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MODULE_API_ROUTER,
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MODULE_BETA_RELEASE,
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ROUTER_VERSION,
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"A connection based router to load balance based on connections"
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};
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static char *version_str = "V1.1.0";
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/* The router entry points */
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static ROUTER *createInstance(SERVICE *service, char **options);
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static void *newSession(ROUTER *instance, SESSION *session);
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static void closeSession(ROUTER *instance, void *router_session);
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static void freeSession(ROUTER *instance, void *router_session);
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static int routeQuery(ROUTER *instance, void *router_session, GWBUF *queue);
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static void diagnostics(ROUTER *instance, DCB *dcb);
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static void clientReply(
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ROUTER *instance,
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void *router_session,
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GWBUF *queue,
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DCB *backend_dcb);
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static void handleError(
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ROUTER *instance,
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void *router_session,
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GWBUF *errbuf,
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DCB *backend_dcb,
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error_action_t action,
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bool *succp);
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static uint8_t getCapabilities (ROUTER* inst, void* router_session);
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/** The module object definition */
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static ROUTER_OBJECT MyObject = {
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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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};
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static bool rses_begin_locked_router_action(
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ROUTER_CLIENT_SES* rses);
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static void rses_end_locked_router_action(
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ROUTER_CLIENT_SES* rses);
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static BACKEND *get_root_master(
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BACKEND **servers);
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static SPINLOCK instlock;
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static ROUTER_INSTANCE *instances;
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/**
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* Implementation of the mandatory version entry point
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*
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* @return version string of the module
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*/
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char *
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version()
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{
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return version_str;
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}
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/**
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* The module initialisation routine, called when the module
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* is first loaded.
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*/
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void
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ModuleInit()
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{
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LOGIF(LM, (skygw_log_write(
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LOGFILE_MESSAGE,
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"Initialise readconnroute router module %s.\n", version_str)));
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spinlock_init(&instlock);
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instances = 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 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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ROUTER_OBJECT *
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GetModuleObject()
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{
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return &MyObject;
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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 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 *server;
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int i, n;
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BACKEND *backend;
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char *weightby;
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if ((inst = calloc(1, sizeof(ROUTER_INSTANCE))) == NULL) {
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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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* We need an array of the backend servers in the instance structure so
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* that we can maintain a count of the number of connections to each
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* backend server.
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*/
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for (server = service->databases, n = 0; server; server = server->nextdb)
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n++;
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inst->servers = (BACKEND **)calloc(n + 1, sizeof(BACKEND *));
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if (!inst->servers)
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{
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free(inst);
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return NULL;
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}
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for (server = service->databases, n = 0; server; server = server->nextdb)
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{
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if ((inst->servers[n] = malloc(sizeof(BACKEND))) == NULL)
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{
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for (i = 0; i < n; i++)
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free(inst->servers[i]);
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free(inst->servers);
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free(inst);
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return NULL;
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}
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inst->servers[n]->server = server;
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inst->servers[n]->current_connection_count = 0;
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inst->servers[n]->weight = 1000;
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n++;
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}
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inst->servers[n] = NULL;
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if ((weightby = serviceGetWeightingParameter(service)) != NULL)
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{
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int total = 0;
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for (n = 0; inst->servers[n]; n++)
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{
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backend = inst->servers[n];
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total += atoi(serverGetParameter(backend->server,
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weightby));
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}
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if (total == 0)
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{
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LOGIF(LE, (skygw_log_write(LOGFILE_ERROR,
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"WARNING: Weighting Parameter for service '%s' "
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"will be ignored as no servers have values "
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"for the parameter '%s'.\n",
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service->name, weightby)));
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}
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else
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{
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for (n = 0; inst->servers[n]; n++)
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{
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int perc, wght;
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backend = inst->servers[n];
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perc = ((wght = atoi(serverGetParameter(backend->server,
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weightby))) * 1000) / total;
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if (perc == 0 && wght != 0)
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perc = 1;
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backend->weight = perc;
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if (perc == 0)
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{
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LOGIF(LE, (skygw_log_write(
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LOGFILE_ERROR,
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"Server '%s' has no value "
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"for weighting parameter '%s', "
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"no queries will be routed to "
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"this server.\n",
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inst->servers[n]->server->unique_name,
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weightby)));
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}
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}
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}
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}
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/*
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* Process the options
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*/
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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], "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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LOGIF(LM, (skygw_log_write(
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LOGFILE_MESSAGE,
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"* 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]",
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options[i])));
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}
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}
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}
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/*
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* We have completed the creation of the instance data, so now
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* insert this router instance into the linked list of routers
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* that have been created with this module.
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*/
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spinlock_acquire(&instlock);
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inst->next = instances;
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instances = inst;
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spinlock_release(&instlock);
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return (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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*
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* @param instance The router instance data
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* @param session The session itself
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* @return Session specific data for this session
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*/
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static void *
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newSession(ROUTER *instance, SESSION *session)
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{
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ROUTER_INSTANCE *inst = (ROUTER_INSTANCE *)instance;
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ROUTER_CLIENT_SES *client_rses;
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BACKEND *candidate = NULL;
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int i;
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BACKEND *master_host = NULL;
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LOGIF(LD, (skygw_log_write_flush(
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LOGFILE_DEBUG,
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"%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 *)calloc(1, sizeof(ROUTER_CLIENT_SES));
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if (client_rses == NULL) {
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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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/**
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* Find the Master host from available servers
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*/
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master_host = get_root_master(inst->servers);
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/**
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* Find a backend server to connect to. This is the extent of the
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* load balancing algorithm we need to implement for this simple
|
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* connection router.
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*/
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/*
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* Loop over all the servers and find any that have fewer connections
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* than the candidate server.
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*
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* If a server has less connections than the current candidate we mark this
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* as the new candidate to connect to.
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*
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* If a server has the same number of connections currently as the candidate
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* and has had less connections over time than the candidate it will also
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* become the new candidate. This has the effect of spreading the
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* connections over different servers during periods of very low load.
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*/
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for (i = 0; inst->servers[i]; i++) {
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if(inst->servers[i]) {
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LOGIF(LD, (skygw_log_write(
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LOGFILE_DEBUG,
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"%lu [newSession] Examine server in port %d with "
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"%d connections. Status is %d, "
|
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"inst->bitvalue is %d",
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pthread_self(),
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inst->servers[i]->server->port,
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inst->servers[i]->current_connection_count,
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inst->servers[i]->server->status,
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inst->bitmask)));
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}
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if (SERVER_IN_MAINT(inst->servers[i]->server))
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continue;
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|
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if (inst->servers[i]->weight == 0)
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continue;
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|
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/* Check server status bits against bitvalue from router_options */
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if (inst->servers[i] &&
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SERVER_IS_RUNNING(inst->servers[i]->server) &&
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(inst->servers[i]->server->status & inst->bitmask & inst->bitvalue))
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{
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if (master_host) {
|
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if (inst->servers[i] == master_host && (inst->bitvalue & SERVER_SLAVE)) {
|
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/* skip root Master here, as it could also be slave of an external server
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* that is not in the configuration.
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* Intermediate masters (Relay Servers) are also slave and will be selected
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* as Slave(s)
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*/
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|
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continue;
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}
|
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if (inst->servers[i] == master_host && (inst->bitvalue & SERVER_MASTER)) {
|
|
/* If option is "master" return only the root Master as there
|
|
* could be intermediate masters (Relay Servers)
|
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* and they must not be selected.
|
|
*/
|
|
|
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candidate = master_host;
|
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break;
|
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}
|
|
} else {
|
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/* master_host is NULL, no master server.
|
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* If requested router_option is 'master'
|
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* candidate wll be NULL.
|
|
*/
|
|
if (inst->bitvalue & SERVER_MASTER) {
|
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candidate = NULL;
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break;
|
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}
|
|
}
|
|
|
|
/* If no candidate set, set first running server as
|
|
our initial candidate server */
|
|
if (candidate == NULL)
|
|
{
|
|
candidate = inst->servers[i];
|
|
}
|
|
else if ((inst->servers[i]->current_connection_count
|
|
* 1000) / inst->servers[i]->weight <
|
|
(candidate->current_connection_count *
|
|
1000) / candidate->weight)
|
|
{
|
|
/* This running server has fewer
|
|
connections, set it as a new candidate */
|
|
candidate = inst->servers[i];
|
|
}
|
|
else if ((inst->servers[i]->current_connection_count
|
|
* 1000) / inst->servers[i]->weight ==
|
|
(candidate->current_connection_count *
|
|
1000) / candidate->weight &&
|
|
inst->servers[i]->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 = inst->servers[i];
|
|
}
|
|
}
|
|
}
|
|
|
|
/* There is no candidate server here!
|
|
* With router_option=slave a master_host could be set, so route traffic there.
|
|
* Otherwise, just clean up and return NULL
|
|
*/
|
|
if (!candidate) {
|
|
if (master_host) {
|
|
candidate = master_host;
|
|
} else {
|
|
LOGIF(LE, (skygw_log_write_flush(
|
|
LOGFILE_ERROR,
|
|
"Error : Failed to create new routing session. "
|
|
"Couldn't find eligible candidate server. Freeing "
|
|
"allocated resources.")));
|
|
free(client_rses);
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
client_rses->rses_capabilities = RCAP_TYPE_PACKET_INPUT;
|
|
|
|
/*
|
|
* We now have the server with the least connections.
|
|
* Bump the connection count for this server
|
|
*/
|
|
atomic_add(&candidate->current_connection_count, 1);
|
|
client_rses->backend = candidate;
|
|
LOGIF(LD, (skygw_log_write(
|
|
LOGFILE_DEBUG,
|
|
"%lu [newSession] Selected server in port %d. "
|
|
"Connections : %d\n",
|
|
pthread_self(),
|
|
candidate->server->port,
|
|
candidate->current_connection_count)));
|
|
/*
|
|
* Open a backend connection, putting the DCB for this
|
|
* connection in the client_rses->backend_dcb
|
|
*/
|
|
client_rses->backend_dcb = dcb_connect(candidate->server,
|
|
session,
|
|
candidate->server->protocol);
|
|
if (client_rses->backend_dcb == NULL)
|
|
{
|
|
atomic_add(&candidate->current_connection_count, -1);
|
|
free(client_rses);
|
|
return NULL;
|
|
}
|
|
inst->stats.n_sessions++;
|
|
|
|
/**
|
|
* Add this session to the list of active sessions.
|
|
*/
|
|
spinlock_acquire(&inst->lock);
|
|
client_rses->next = inst->connections;
|
|
inst->connections = client_rses;
|
|
spinlock_release(&inst->lock);
|
|
|
|
CHK_CLIENT_RSES(client_rses);
|
|
|
|
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(
|
|
ROUTER* router_instance,
|
|
void* router_client_ses)
|
|
{
|
|
ROUTER_INSTANCE* router = (ROUTER_INSTANCE *)router_instance;
|
|
ROUTER_CLIENT_SES* router_cli_ses =
|
|
(ROUTER_CLIENT_SES *)router_client_ses;
|
|
int prev_val;
|
|
|
|
prev_val = atomic_add(&router_cli_ses->backend->current_connection_count, -1);
|
|
ss_dassert(prev_val > 0);
|
|
|
|
spinlock_acquire(&router->lock);
|
|
|
|
if (router->connections == router_cli_ses) {
|
|
router->connections = router_cli_ses->next;
|
|
} else {
|
|
ROUTER_CLIENT_SES *ptr = router->connections;
|
|
|
|
while (ptr != NULL && ptr->next != router_cli_ses) {
|
|
ptr = ptr->next;
|
|
}
|
|
|
|
if (ptr != NULL) {
|
|
ptr->next = router_cli_ses->next;
|
|
}
|
|
}
|
|
spinlock_release(&router->lock);
|
|
|
|
LOGIF(LD, (skygw_log_write_flush(
|
|
LOGFILE_DEBUG,
|
|
"%lu [freeSession] Unlinked router_client_session %p from "
|
|
"router %p and from server on port %d. Connections : %d. ",
|
|
pthread_self(),
|
|
router_cli_ses,
|
|
router,
|
|
router_cli_ses->backend->server->port,
|
|
prev_val-1)));
|
|
|
|
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(ROUTER *instance, void *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 */
|
|
atomic_add(&router_cli_ses->backend->server->stats.n_current, -1);
|
|
|
|
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);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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 The number of bytes sent
|
|
*/
|
|
static int
|
|
routeQuery(ROUTER *instance, void *router_session, GWBUF *queue)
|
|
{
|
|
ROUTER_INSTANCE *inst = (ROUTER_INSTANCE *)instance;
|
|
ROUTER_CLIENT_SES *router_cli_ses = (ROUTER_CLIENT_SES *)router_session;
|
|
uint8_t *payload = GWBUF_DATA(queue);
|
|
int mysql_command;
|
|
int rc;
|
|
DCB* backend_dcb;
|
|
bool rses_is_closed;
|
|
|
|
inst->stats.n_queries++;
|
|
mysql_command = MYSQL_GET_COMMAND(payload);
|
|
|
|
/** 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)
|
|
{
|
|
LOGIF(LT, (skygw_log_write(
|
|
LOGFILE_TRACE,
|
|
"Error : Failed to route MySQL command %d to backend "
|
|
"server.",
|
|
mysql_command)));
|
|
goto return_rc;
|
|
}
|
|
|
|
switch(mysql_command) {
|
|
case MYSQL_COM_CHANGE_USER:
|
|
rc = backend_dcb->func.auth(
|
|
backend_dcb,
|
|
NULL,
|
|
backend_dcb->session,
|
|
queue);
|
|
break;
|
|
default:
|
|
rc = backend_dcb->func.write(backend_dcb, queue);
|
|
break;
|
|
}
|
|
|
|
CHK_PROTOCOL(((MySQLProtocol*)backend_dcb->protocol));
|
|
LOGIF(LD, (skygw_log_write(
|
|
LOGFILE_DEBUG,
|
|
"%lu [readconnroute:routeQuery] Routed command %d to dcb %p "
|
|
"with return value %d.",
|
|
pthread_self(),
|
|
mysql_command,
|
|
backend_dcb,
|
|
rc)));
|
|
return_rc:
|
|
return rc;
|
|
}
|
|
|
|
/**
|
|
* Display router diagnostics
|
|
*
|
|
* @param instance Instance of the router
|
|
* @param dcb DCB to send diagnostics to
|
|
*/
|
|
static void
|
|
diagnostics(ROUTER *router, DCB *dcb)
|
|
{
|
|
ROUTER_INSTANCE *router_inst = (ROUTER_INSTANCE *)router;
|
|
ROUTER_CLIENT_SES *session;
|
|
int i = 0;
|
|
BACKEND *backend;
|
|
char *weightby;
|
|
|
|
spinlock_acquire(&router_inst->lock);
|
|
session = router_inst->connections;
|
|
while (session)
|
|
{
|
|
i++;
|
|
session = session->next;
|
|
}
|
|
spinlock_release(&router_inst->lock);
|
|
|
|
dcb_printf(dcb, "\tNumber of router sessions: %d\n",
|
|
router_inst->stats.n_sessions);
|
|
dcb_printf(dcb, "\tCurrent no. of router sessions: %d\n", i);
|
|
dcb_printf(dcb, "\tNumber of queries forwarded: %d\n",
|
|
router_inst->stats.n_queries);
|
|
if ((weightby = serviceGetWeightingParameter(router_inst->service))
|
|
!= NULL)
|
|
{
|
|
dcb_printf(dcb, "\tConnection distribution based on %s "
|
|
"server parameter.\n",
|
|
weightby);
|
|
dcb_printf(dcb,
|
|
"\t\tServer Target %% Connections\n");
|
|
for (i = 0; router_inst->servers[i]; i++)
|
|
{
|
|
backend = router_inst->servers[i];
|
|
dcb_printf(dcb, "\t\t%-20s %3.1f%% %d\n",
|
|
backend->server->unique_name,
|
|
(float)backend->weight / 10,
|
|
backend->current_connection_count);
|
|
}
|
|
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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(
|
|
ROUTER *instance,
|
|
void *router_session,
|
|
GWBUF *queue,
|
|
DCB *backend_dcb)
|
|
{
|
|
DCB *client = NULL;
|
|
|
|
client = backend_dcb->session->client;
|
|
|
|
ss_dassert(client != NULL);
|
|
|
|
SESSION_ROUTE_REPLY(backend_dcb->session, queue);
|
|
}
|
|
|
|
/**
|
|
* Error Handler routine
|
|
*
|
|
* The routine will handle errors that occurred in backend writes.
|
|
*
|
|
* @param instance The router instance
|
|
* @param router_session The router session
|
|
* @param message The error message to reply
|
|
* @param backend_dcb The backend DCB
|
|
* @param action The action: REPLY, REPLY_AND_CLOSE, NEW_CONNECTION
|
|
*
|
|
*/
|
|
static void
|
|
handleError(
|
|
ROUTER *instance,
|
|
void *router_session,
|
|
GWBUF *errbuf,
|
|
DCB *backend_dcb,
|
|
error_action_t action,
|
|
bool *succp)
|
|
{
|
|
DCB *client = NULL;
|
|
SESSION *session = backend_dcb->session;
|
|
client = session->client;
|
|
|
|
ss_dassert(client != NULL);
|
|
}
|
|
|
|
/** 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 uint8_t getCapabilities(
|
|
ROUTER* inst,
|
|
void* router_session)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
/********************************
|
|
* 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 BACKEND *get_root_master(BACKEND **servers) {
|
|
int i = 0;
|
|
BACKEND *master_host = NULL;
|
|
|
|
for (i = 0; servers[i]; i++) {
|
|
if (servers[i] && (servers[i]->server->status & (SERVER_MASTER|SERVER_MAINT)) == SERVER_MASTER) {
|
|
if (master_host && servers[i]->server->depth < master_host->server->depth) {
|
|
master_host = servers[i];
|
|
} else {
|
|
if (master_host == NULL) {
|
|
master_host = servers[i];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return master_host;
|
|
}
|