02e60e215b
Addition of code for dynamic reconfiguration by editign the cnf file and sendign a SIGHUP Improvements to the make install rule
573 lines
18 KiB
C
573 lines
18 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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#include <stdio.h>
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#include <strings.h>
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#include <string.h>
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#include <router.h>
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#include <readwritesplit.h>
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#include <stdlib.h>
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#include <mysql.h>
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#include <skygw_utils.h>
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#include <log_manager.h>
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#include <query_classifier.h>
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#include <dcb.h>
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#include <spinlock.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.
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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
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* from master only in case of session change
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*
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* @endverbatim
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*/
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static char *version_str = "V1.0.1";
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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 *session);
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static int routeQuery(ROUTER *instance, void *session, GWBUF *queue);
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static void diagnostic(ROUTER *instance, DCB *dcb);
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static void clientReply(ROUTER* instance, void* router_session, GWBUF* queue, DCB *backend_dcb);
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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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routeQuery,
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diagnostic,
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clientReply };
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static SPINLOCK instlock;
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static 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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skygw_log_write_flush(NULL,
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LOGFILE_MESSAGE,
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"Initialize read/write split router module.\n");
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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* GetModuleObject() {
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skygw_log_write(NULL,
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LOGFILE_TRACE,
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"Returning readwritesplit router module object.");
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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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* The job of ths entry point is to create the service wide data needed
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* for the query router. This is information needed to route queries that
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* is not related to any individual client session, exmaples of data that
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* might be stored in the ROUTER object for a particular query router are
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* connections counts, last used connection etc so that balancing may
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* take place.
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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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*
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* @return The instance data for this new instance
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*/
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static ROUTER* createInstance(
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SERVICE* service,
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char** options)
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{
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INSTANCE* inst;
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SERVER* server;
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int n;
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int i;
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if ((inst = calloc(1, sizeof(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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inst->connections = NULL;
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/** Calculate number of servers */
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for (server = service->databases, n = 0; server; server = server->nextdb) {
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n++;
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}
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inst->servers = (BACKEND **)calloc(n + 1, sizeof(BACKEND *));
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if (!inst->servers) {
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free(inst);
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return NULL;
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}
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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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if ((inst->servers[n] = malloc(sizeof(BACKEND))) == NULL) {
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for (i = 0; i < n; i++) {
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free(inst->servers[i]);
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}
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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]->count = 0;
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n++;
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}
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inst->servers[n] = NULL;
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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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* The session is used to store all the data required for a particular
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* client connection.
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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* newSession(
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ROUTER* instance,
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SESSION* session)
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{
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BACKEND* candidate = NULL;
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CLIENT_SESSION* client;
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INSTANCE* inst = (INSTANCE *)instance;
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int i;
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if ((client = (CLIENT_SESSION *)malloc(sizeof(CLIENT_SESSION))) == NULL)
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{
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return NULL;
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}
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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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for (i = 0; inst->servers[i]; i++)
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{
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if (inst->servers[i] && SERVER_IS_SLAVE(inst->servers[i]->server))
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{
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candidate = inst->servers[i];
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break;
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}
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}
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/**
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* Loop over all the servers and find any that have fewer connections than our
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* 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 connections
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* 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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&& SERVER_IS_RUNNING(inst->servers[i]->server))
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{
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if (SERVER_IS_SLAVE(inst->servers[i]->server))
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{
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if (inst->servers[i]->count < candidate->count) {
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candidate = inst->servers[i];
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} else if (inst->servers[i]->count == candidate->count &&
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inst->servers[i]->server->stats.n_connections
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< candidate->server->stats.n_connections)
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{
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candidate = inst->servers[i];
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}
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} else if (SERVER_IS_MASTER(inst->servers[i]->server)) {
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/** master is found */
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inst->master = inst->servers[i];
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}
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}
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} /* for */
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if (inst->master == NULL) {
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inst->master = inst->servers[i-1];
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}
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/**
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* We now have a master and a slave server with the least connections.
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* Bump the connection counts for these servers.
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*/
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atomic_add(&candidate->count, 1);
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client->slave = candidate;
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atomic_add(&inst->master->count, 1);
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client->master = inst->master;
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ss_dassert(client->master->server != candidate->server);
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/**
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* Open the slave connection.
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*/
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if ((client->slaveconn = dcb_connect(candidate->server, session,
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candidate->server->protocol)) == NULL)
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{
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atomic_add(&candidate->count, -1);
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free(client);
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return NULL;
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}
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/**
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* Open the master connection.
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*/
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if ((client->masterconn = dcb_connect(client->master->server, session,
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client->master->server->protocol)) == NULL)
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{
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atomic_add(&client->master->count, -1);
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free(client);
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return NULL;
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}
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inst->stats.n_sessions += 1;
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/* Add this session to end of the list of active sessions */
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spinlock_acquire(&inst->lock);
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client->next = inst->connections;
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inst->connections = client;
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spinlock_release(&inst->lock);
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return (void *)client;
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}
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/**
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* Close a session with the router, this is the mechanism
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* by which a router may cleanup data structure etc.
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*
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* @param instance The router instance data
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* @param router_session The session being closed
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*/
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static void closeSession(
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ROUTER* instance,
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void* router_session)
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{
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INSTANCE* inst = (INSTANCE *)instance;
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CLIENT_SESSION* session = (CLIENT_SESSION *)router_session;
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/**
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* Close the connection to the backend servers
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*/
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session->slaveconn->func.close(session->slaveconn);
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session->masterconn->func.close(session->masterconn);
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atomic_add(&session->slave->count, -1);
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atomic_add(&session->master->count, -1);
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atomic_add(&session->slave->server->stats.n_current, -1);
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atomic_add(&session->master->server->stats.n_current, -1);
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spinlock_acquire(&inst->lock);
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if (inst->connections == session) {
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inst->connections = session->next;
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} else {
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CLIENT_SESSION* ptr = inst->connections;
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while (ptr && ptr->next != session) {
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ptr = ptr->next;
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}
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if (ptr) {
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ptr->next = session->next;
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}
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}
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spinlock_release(&inst->lock);
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/*
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* We are no longer in the linked list, free
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* all the memory and other resources associated
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* to the client session.
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*/
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free(session);
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}
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/**
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* The main routing entry, this is called with every packet that is
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* received and has to be forwarded to the backend database.
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*
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* The routeQuery will make the routing decision based on the contents
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* of the instance, session and the query itself in the queue. The
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* data in the queue may not represent a complete query, it represents
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* the data that has been received. The query router itself is responsible
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* for buffering the partial query, a later call to the query router will
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* contain the remainder, or part thereof of the query.
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*
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* @param instance The query router instance
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* @param router_session The session associated with the client
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* @param queue Gateway buffer queue with the packets received
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*
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* @return The number of queries forwarded
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*/
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static int routeQuery(
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ROUTER* instance,
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void* router_session,
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GWBUF* queue)
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{
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skygw_query_type_t qtype = QUERY_TYPE_UNKNOWN;
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char* querystr = NULL;
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char* startpos;
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size_t len;
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unsigned char packet_type, *packet;
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int ret = 0;
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INSTANCE* inst = (INSTANCE *)instance;
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CLIENT_SESSION* session = (CLIENT_SESSION *)router_session;
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inst->stats.n_queries++;
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packet = GWBUF_DATA(queue);
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packet_type = packet[4];
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startpos = (char *)&packet[5];
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len = packet[0];
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len += 255*packet[1];
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len += 255*255*packet[2];
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switch(packet_type) {
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case COM_INIT_DB: /**< 2 DDL must go to the master */
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case COM_REFRESH: /**< 7 - I guess this is session but not sure */
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case COM_DEBUG: /**< 0d all servers dump debug info to stdout */
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case COM_PING: /**< 0e all servers are pinged */
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case COM_CHANGE_USER: /**< 11 all servers change it accordingly */
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qtype = QUERY_TYPE_SESSION_WRITE;
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break;
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case COM_CREATE_DB: /**< 5 DDL must go to the master */
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case COM_DROP_DB: /**< 6 DDL must go to the master */
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qtype = QUERY_TYPE_WRITE;
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break;
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case COM_QUERY:
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querystr = (char *)malloc(len);
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memcpy(querystr, startpos, len-1);
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memset(&querystr[len-1], 0, 1);
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qtype = skygw_query_classifier_get_type(querystr, 0);
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break;
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default:
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case COM_SHUTDOWN: /**< 8 where should shutdown be routed ? */
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case COM_STATISTICS: /**< 9 ? */
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case COM_PROCESS_INFO: /**< 0a ? */
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case COM_CONNECT: /**< 0b ? */
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case COM_PROCESS_KILL: /**< 0c ? */
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case COM_TIME: /**< 0f should this be run in gateway ? */
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case COM_DELAYED_INSERT: /**< 10 ? */
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case COM_DAEMON: /**< 1d ? */
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break;
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}
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#if defined(SS_DEBUG_)
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skygw_log_write(NULL, LOGFILE_TRACE, "String\t\"%s\"", querystr);
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skygw_log_write(NULL,
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LOGFILE_TRACE,
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"Packet type\t%s",
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STRPACKETTYPE(packet_type));
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#endif
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switch (qtype) {
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case QUERY_TYPE_WRITE:
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#if defined(SS_DEBUG_)
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skygw_log_write(NULL,
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LOGFILE_TRACE,
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"Query type\t%s, routing to Master.",
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STRQTYPE(qtype));
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#endif
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ret = session->masterconn->func.write(session->masterconn, queue);
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atomic_add(&inst->stats.n_master, 1);
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goto return_ret;
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break;
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case QUERY_TYPE_READ:
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#if defined(SS_DEBUG_)
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skygw_log_write(NULL,
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LOGFILE_TRACE,
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"Query type\t%s, routing to Slave.",
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STRQTYPE(qtype));
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#endif
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ret = session->slaveconn->func.write(session->slaveconn, queue);
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atomic_add(&inst->stats.n_slave, 1);
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goto return_ret;
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break;
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case QUERY_TYPE_SESSION_WRITE:
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#if defined(SS_DEBUG_)
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skygw_log_write(NULL,
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LOGFILE_TRACE,
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"Query type\t%s, routing to All servers.",
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STRQTYPE(qtype));
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#endif
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/**
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* TODO! Connection to all servers must be established, and
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* the command must be executed in them.
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*/
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if (packet_type != COM_CHANGE_USER)
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{
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GWBUF *cq = gwbuf_clone(queue);
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ret = session->masterconn->func.session(session->masterconn, (void *)queue);
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session->slaveconn->func.session(session->slaveconn, (void *)cq);
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} else {
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GWBUF *cq = gwbuf_clone(queue);
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session->masterconn->func.auth(session->masterconn, NULL, session->masterconn->session, queue);
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session->slaveconn->func.auth(session->slaveconn, NULL, session->masterconn->session, cq);
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}
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atomic_add(&inst->stats.n_all, 1);
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goto return_ret;
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break;
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default:
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#if defined(SS_DEBUG_)
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skygw_log_write(NULL,
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LOGFILE_TRACE,
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"Query type\t%s, routing to Master by default.",
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STRQTYPE(qtype));
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#endif
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/** Is this really ok? */
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ret = session->masterconn->func.write(session->masterconn, queue);
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atomic_add(&inst->stats.n_master, 1);
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goto return_ret;
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break;
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}
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return_ret:
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free(querystr);
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return ret;
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}
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/**
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* Diagnostics routine
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*
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* Print query router statistics to the DCB passed in
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*
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* @param instance The router instance
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* @param dcb The DCB for diagnostic output
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*/
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static void
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diagnostic(ROUTER *instance, DCB *dcb)
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{
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CLIENT_SESSION *session;
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INSTANCE *inst = (INSTANCE *)instance;
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int i = 0;
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spinlock_acquire(&inst->lock);
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session = inst->connections;
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while (session)
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{
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i++;
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session = session->next;
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}
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spinlock_release(&inst->lock);
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dcb_printf(dcb, "\tNumber of router sessions: %d\n", inst->stats.n_sessions);
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dcb_printf(dcb, "\tCurrent no. of router sessions: %d\n", i);
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dcb_printf(dcb, "\tNumber of queries forwarded: %d\n", inst->stats.n_queries);
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dcb_printf(dcb, "\tNumber of queries forwarded to master: %d\n", inst->stats.n_master);
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dcb_printf(dcb, "\tNumber of queries forwarded to slave: %d\n", inst->stats.n_slave);
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dcb_printf(dcb, "\tNumber of queries forwarded to all: %d\n", inst->stats.n_all);
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}
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/**
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* Client Reply routine
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*
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* The routine will reply to client for session change with master server data
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*
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* @param instance The router instance
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* @param router_session The router session
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* @param backend_dcb The backend DCB
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* @param queue The GWBUF with reply data
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*/
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static void
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clientReply(ROUTER* instance, void* router_session, GWBUF* queue, DCB *backend_dcb)
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{
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INSTANCE* inst = NULL;
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DCB *master = NULL;
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DCB *client = NULL;
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CLIENT_SESSION* session = NULL;
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inst = (INSTANCE *)instance;
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session = (CLIENT_SESSION *)router_session;
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master = session->masterconn;
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client = backend_dcb->session->client;
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if (backend_dcb->command == ROUTER_CHANGE_SESSION) {
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/* if backend_dcb is the master we can reply to the client */
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if (backend_dcb == master) {
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master->session->client->func.write(master->session->client, queue);
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} else {
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/* just consume the gwbuf without writing to the client */
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gwbuf_consume(queue, gwbuf_length(queue));
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}
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} else {
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/* normal flow */
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client->func.write(client, queue);
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}
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}
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///
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