二、Redis服务启动以及请求流程
上一次我们大概熟悉了一下redis的目录结构，里面提到了服务启动相关的源码主要包含如下两个文件：
找到server.c文件中的main函数开始了解服务的启动过程：
源码解析：
1、主流程：
/* Global vars */ // 全局变量 struct redisServer server; /* Server global state */ volatile unsigned long lru_clock; /* Server global current LRU time. */ struct redisCommand redisCommandTable[] ={...} /* Our command table.*/ int main(int argc, char **argv) { // 主入口 struct timeval tv; int j; #ifdef REDIS_TEST // redis测试环境设置 if (argc == 3 && !strcasecmp(argv[1], test)) { ...return -1; /* test not found */ } #endif /* We need to initialize our libraries, and the server configuration. */ // 初始化库和服务器配置。 #ifdef INIT_SETPROCTITLE_REPLACEMENT spt_init(argc, argv); #endif // 设置相关默认值
setlocale(LC_COLLATE,); tzset(); /* Populates 'timezone' global. */
zmalloc_set_oom_handler(redisOutOfMemoryHandler); srand(time(NULL)^getpid()); gettimeofday(&tv,NULL); char hashseed[16]; getRandomHexChars(hashseed,sizeof(hashseed)); dictSetHashFunctionSeed((uint8_t*)hashseed); // 哨兵模式
server.sentinel_mode = checkForSentinelMode(argc,argv); // 默认配置加载
initServerConfig(); moduleInitModulesSystem(); /* Store the executable path and arguments in a safe place in order * to be able to restart the server later. */ server.executable = getAbsolutePath(argv[0]); server.exec_argv = zmalloc(sizeof(char*)*(argc+1)); server.exec_argv[argc] = NULL; for (j = 0; j < argc; j++) server.exec_argv[j] = zstrdup(argv[j]); /* We need to init sentinel right now as parsing the configuration file * in sentinel mode will have the effect of populating the sentinel * data structures with master nodes to monitor. */ if (server.sentinel_mode) { initSentinelConfig(); initSentinel(); }
// 加载配置文件 /* Check if we need to start in redis-check-rdb/aof mode. We just execute * the program main. However the program is part of the Redis executable * so that we can easily execute an RDB check on loading errors. */ if (strstr(argv[0],redis-check-rdb) != NULL) redis_check_rdb_main(argc,argv,NULL); else if (strstr(argv[0],redis-check-aof) != NULL) redis_check_aof_main(argc,argv); if (argc >= 2) { j = 1; /* First option to parse in argv[] */ sds options = sdsempty(); char *configfile = NULL; /* Handle special options --help and --version */ if (strcmp(argv[1], -v) == 0 || strcmp(argv[1], --version) == 0) version(); if (strcmp(argv[1], --help) == 0 || strcmp(argv[1], -h) == 0) usage(); if (strcmp(argv[1], --test-memory) == 0) { if (argc == 3) { memtest(atoi(argv[2]),50); exit(0); } else { fprintf(stderr,Please specify the amount of memory to test in megabytes.\n); fprintf(stderr,Example: ./redis-server --test-memory 4096\n\n); exit(1); } } /* First argument is the config file name? */ if (argv[j][0] != '-' || argv[j][1] != '-') { configfile = argv[j]; server.configfile = getAbsolutePath(configfile); /* Replace the config file in server.exec_argv with * its absolute path. */ zfree(server.exec_argv[j]); server.exec_argv[j] = zstrdup(server.configfile); j++; } /* All the other options are parsed and conceptually appended to the * configuration file. For instance --port 6380 will generate the * string port 6380\n to be parsed after the actual file name * is parsed, if any. */ while(j != argc) { if (argv[j][0] == '-' && argv[j][1] == '-') { /* Option name */ if (!strcmp(argv[j], --check-rdb)) { /* Argument has no options, need to skip for parsing. */ j++; continue; } if (sdslen(options)) options = sdscat(options,\n); options = sdscat(options,argv[j]+2); options = sdscat(options, ); } else { /* Option argument */ options = sdscatrepr(options,argv[j],strlen(argv[j])); options = sdscat(options, ); } j++; } if (server.sentinel_mode && configfile && *configfile == '-') { serverLog(LL_WARNING, Sentinel config from STDIN not allowed.); serverLog(LL_WARNING, Sentinel needs config file on disk to save state. Exiting...); exit(1); } resetServerSaveParams(); // 加载配置文件
loadServerConfig(configfile,options); sdsfree(options); } serverLog(LL_WARNING, oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo); serverLog(LL_WARNING, Redis version=%s, bits=%d, commit=%s, modified=%d, pid=%d, just started, REDIS_VERSION, (sizeof(long) == 8) ? 64 : 32, redisGitSHA1(), strtol(redisGitDirty(),NULL,10) > 0, (int)getpid()); if (argc == 1) { serverLog(LL_WARNING, Warning: no config file specified, using the default config. In order to specify a config file use %s /path/to/%s.conf, argv[0], server.sentinel_mode ? sentinel : redis); } else { serverLog(LL_WARNING, Configuration loaded); } server.supervised = redisIsSupervised(server.supervised_mode); int background = server.daemonize && !server.supervised; if (background) daemonize(); // 初始化服务器
initServer(); if (background || server.pidfile) createPidFile(); redisSetProcTitle(argv[0]); redisAsciiArt(); checkTcpBacklogSettings(); if (!server.sentinel_mode) { /* Things not needed when running in Sentinel mode. */ // 非哨兵模式执行此逻辑 serverLog(LL_WARNING,Server initialized); #ifdef __linux__ linuxMemoryWarnings(); #if defined (__arm64__) int ret; if ((ret = linuxMadvFreeForkBugCheck())) { if (ret == 1) serverLog(LL_WARNING,WARNING Your kernel has a bug that could lead to data corruption during background save. Please upgrade to the latest stable kernel.); else serverLog(LL_WARNING, Failed to test the kernel for a bug that could lead to data corruption during background save. Your system could be affected, please report this error.); if (!checkIgnoreWarning(ARM64-COW-BUG)) { serverLog(LL_WARNING,Redis will now exit to prevent data corruption. Note that it is possible to suppress this warning by setting the following config: ignore-warnings ARM64-COW-BUG); exit(1); } } #endif /* __arm64__ */ #endif /* __linux__ */ // 数据恢复
moduleLoadFromQueue(); InitServerLast(); loadDataFromDisk(); if (server.cluster_enabled) { if (verifyClusterConfigWithData() == C_ERR) { serverLog(LL_WARNING, You can't have keys in a DB different than DB 0 when in Cluster mode. Exiting.); exit(1); } } if (server.ipfd_count > 0) serverLog(LL_NOTICE,Ready to accept connections); if (server.sofd > 0) serverLog(LL_NOTICE,The server is now ready to accept connections at %s, server.unixsocket); } else { InitServerLast(); // 哨兵模式执行 sentinelIsRunning(); } /* Warning the user about suspicious maxmemory setting. */ if (server.maxmemory > 0 && server.maxmemory < 1024*1024) { serverLog(LL_WARNING,WARNING: You specified a maxmemory value that is less than 1MB (current value is %llu bytes). Are you sure this is what you really want?, server.maxmemory); } aeSetBeforeSleepProc(server.el,beforeSleep); aeSetAfterSleepProc(server.el,afterSleep); aeMain(server.el); // 关闭服务
aeDeleteEventLoop(server.el); return 0; }
2、配置参数
// 默认配置加载
initServerConfig(); 核心代码对象赋值（struct redisServer server;）
// 加载配置文件
loadServerConfig(configfile,options) 》》》 void loadServerConfigFromString(char *config){ ... strcasecmp(argv[0],port) ... } 配置文件加载数据
3、初始化服务
--20220510待更新
void initServer(void) { int j; signal(SIGHUP, SIG_IGN); signal(SIGPIPE, SIG_IGN); setupSignalHandlers(); if (server.syslog_enabled) { openlog(server.syslog_ident, LOG_PID | LOG_NDELAY | LOG_NOWAIT, server.syslog_facility); } server.hz = server.config_hz; server.pid = getpid(); server.current_client = NULL; server.fixed_time_expire = 0; server.clients = listCreate(); server.clients_index = raxNew(); server.clients_to_close = listCreate(); server.slaves = listCreate(); server.monitors = listCreate(); server.clients_pending_write = listCreate(); server.slaveseldb = -1; /* Force to emit the first SELECT command. */ server.unblocked_clients = listCreate(); server.ready_keys = listCreate(); server.clients_waiting_acks = listCreate(); server.get_ack_from_slaves = 0; server.clients_paused = 0; server.system_memory_size = zmalloc_get_memory_size(); createSharedObjects(); adjustOpenFilesLimit(); server.el = aeCreateEventLoop(server.maxclients+CONFIG_FDSET_INCR); if (server.el == NULL) { serverLog(LL_WARNING, Failed creating the event loop. Error message: '%s', strerror(errno)); exit(1); } server.db = zmalloc(sizeof(redisDb)*server.dbnum); /* Open the TCP listening socket for the user commands. */ if (server.port != 0 && listenToPort(server.port,server.ipfd,&server.ipfd_count) == C_ERR) exit(1); /* Open the listening Unix domain socket. */ if (server.unixsocket != NULL) { unlink(server.unixsocket); /* don't care if this fails */ server.sofd = anetUnixServer(server.neterr,server.unixsocket, server.unixsocketperm, server.tcp_backlog); if (server.sofd == ANET_ERR) { serverLog(LL_WARNING, Opening Unix socket: %s, server.neterr); exit(1); } anetNonBlock(NULL,server.sofd); } /* Abort if there are no listening sockets at all. */ if (server.ipfd_count == 0 && server.sofd < 0) { serverLog(LL_WARNING, Configured to not listen anywhere, exiting.); exit(1); } /* Create the Redis databases, and initialize other internal state. */ for (j = 0; j < server.dbnum; j++) { server.db[j].dict = dictCreate(&dbDictType,NULL); server.db[j].expires = dictCreate(&keyptrDictType,NULL); server.db[j].blocking_keys = dictCreate(&keylistDictType,NULL); server.db[j].ready_keys = dictCreate(&objectKeyPointerValueDictType,NULL); server.db[j].watched_keys = dictCreate(&keylistDictType,NULL); server.db[j].id = j; server.db[j].avg_ttl = 0; server.db[j].defrag_later = listCreate(); } evictionPoolAlloc(); /* Initialize the LRU keys pool. */ server.pubsub_channels = dictCreate(&keylistDictType,NULL); server.pubsub_patterns = listCreate(); listSetFreeMethod(server.pubsub_patterns,freePubsubPattern); listSetMatchMethod(server.pubsub_patterns,listMatchPubsubPattern); server.cronloops = 0; server.rdb_child_pid = -1; server.aof_child_pid = -1; server.rdb_child_type = RDB_CHILD_TYPE_NONE; server.rdb_bgsave_scheduled = 0; server.child_info_pipe[0] = -1; server.child_info_pipe[1] = -1; server.child_info_data.magic = 0; aofRewriteBufferReset(); server.aof_buf = sdsempty(); server.lastsave = time(NULL); /* At startup we consider the DB saved. */ server.lastbgsave_try = 0; /* At startup we never tried to BGSAVE. */ server.rdb_save_time_last = -1; server.rdb_save_time_start = -1; server.dirty = 0; resetServerStats(); /* A few stats we don't want to reset: server startup time, and peak mem. */ server.stat_starttime = time(NULL); server.stat_peak_memory = 0; server.stat_rdb_cow_bytes = 0; server.stat_aof_cow_bytes = 0; server.cron_malloc_stats.zmalloc_used = 0; server.cron_malloc_stats.process_rss = 0; server.cron_malloc_stats.allocator_allocated = 0; server.cron_malloc_stats.allocator_active = 0; server.cron_malloc_stats.allocator_resident = 0; server.lastbgsave_status = C_OK; server.aof_last_write_status = C_OK; server.aof_last_write_errno = 0; server.repl_good_slaves_count = 0; /* Create the timer callback, this is our way to process many background * operations incrementally, like clients timeout, eviction of unaccessed * expired keys and so forth. */ if (aeCreateTimeEvent(server.el, 1, serverCron, NULL, NULL) == AE_ERR) { serverPanic(Can't create event loop timers.); exit(1); } /* Create an event handler for accepting new connections in TCP and Unix * domain sockets. */ for (j = 0; j < server.ipfd_count; j++) { if (aeCreateFileEvent(server.el, server.ipfd[j], AE_READABLE, acceptTcpHandler,NULL) == AE_ERR) { serverPanic( Unrecoverable error creating server.ipfd file event.); } } if (server.sofd > 0 && aeCreateFileEvent(server.el,server.sofd,AE_READABLE, acceptUnixHandler,NULL) == AE_ERR) serverPanic(Unrecoverable error creating server.sofd file event.); /* Register a readable event for the pipe used to awake the event loop * when a blocked client in a module needs attention. */ if (aeCreateFileEvent(server.el, server.module_blocked_pipe[0], AE_READABLE, moduleBlockedClientPipeReadable,NULL) == AE_ERR) { serverPanic( Error registering the readable event for the module blocked clients subsystem.); } /* Open the AOF file if needed. */ if (server.aof_state == AOF_ON) { server.aof_fd = open(server.aof_filename, O_WRONLY|O_APPEND|O_CREAT,0644); if (server.aof_fd == -1) { serverLog(LL_WARNING, Can't open the append-only file: %s, strerror(errno)); exit(1); } } /* 32 bit instances are limited to 4GB of address space, so if there is * no explicit limit in the user provided configuration we set a limit * at 3 GB using maxmemory with 'noeviction' policy'. This avoids * useless crashes of the Redis instance for out of memory. */ if (server.arch_bits == 32 && server.maxmemory == 0) { serverLog(LL_WARNING,Warning: 32 bit instance detected but no memory limit set. Setting 3 GB maxmemory limit with 'noeviction' policy now.); server.maxmemory = 3072LL*(1024*1024); /* 3 GB */ server.maxmemory_policy = MAXMEMORY_NO_EVICTION; } if (server.cluster_enabled) clusterInit(); replicationScriptCacheInit(); scriptingInit(1); slowlogInit(); latencyMonitorInit(); }