Redis server启动源码

入口main函数

src/redis.c文件main函数

int main(int argc, char **argv) {
    struct timeval tv;

    /* We need to initialize our libraries, and the server configuration. */
    // 初始化库
#ifdef INIT_SETPROCTITLE_REPLACEMENT
    spt_init(argc, argv);
#endif
    //设置本地时间
    setlocale(LC_COLLATE,"");
    zmalloc_enable_thread_safeness();
    zmalloc_set_oom_handler(redisOutOfMemoryHandler);
    srand(time(NULL)^getpid());
    gettimeofday(&tv,NULL);
    //设置随机数种子
    dictSetHashFunctionSeed(tv.tv_sec^tv.tv_usec^getpid());

    // 检查服务器是否以 Sentinel 模式启动
    server.sentinel_mode = checkForSentinelMode(argc,argv);

    // 初始化服务器
    initServerConfig();

    /* 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. */
    // 如果服务器以 Sentinel 模式启动，那么进行 Sentinel 功能相关的初始化
    // 并为要监视的主服务器创建一些相应的数据结构
    if (server.sentinel_mode) {
        initSentinelConfig();
        initSentinel();
    }

    // 检查用户是否指定了配置文件，或者配置选项
    if (argc >= 2) {
        int j = 1; /* First option to parse in argv[] */
        sds options = sdsempty();
        char *configfile = NULL;

        /* Handle special options --help and --version */
        // 处理特殊选项 -h 、-v 和 --test-memory
        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? */
        // 如果第一个参数（argv[1]）不是以 "--" 开头
        // 那么它应该是一个配置文件
        if (argv[j][0] != '-' || argv[j][1] != '-')
            configfile = argv[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. */
        // 对用户给定的其余选项进行分析，并将分析所得的字符串追加稍后载入的配置文件的内容之后
        // 比如 --port 6380 会被分析为 "port 6380\n"
        while(j != argc) {
            if (argv[j][0] == '-' && argv[j][1] == '-') {
                /* Option name */
                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 (configfile) server.configfile = getAbsolutePath(configfile);
        // 重置保存条件
        resetServerSaveParams();

        // 载入配置文件， options 是前面分析出的给定选项
        loadServerConfig(configfile,options);
        sdsfree(options);

        // 获取配置文件的绝对路径
        if (configfile) server.configfile = getAbsolutePath(configfile);
    } else {
        redisLog(REDIS_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");
    }

    // 将服务器设置为守护进程
    if (server.daemonize) daemonize();

    // 创建并初始化服务器数据结构
    initServer();

    // 如果服务器是守护进程，那么创建 PID 文件
    if (server.daemonize) createPidFile();

    // 为服务器进程设置名字
    redisSetProcTitle(argv[0]);

    // 打印 ASCII LOGO
    redisAsciiArt();

    // 如果服务器不是运行在 SENTINEL 模式，那么执行以下代码
    if (!server.sentinel_mode) {
        /* Things not needed when running in Sentinel mode. */
        // 打印问候语
        redisLog(REDIS_WARNING,"Server started, Redis version " REDIS_VERSION);
    #ifdef __linux__
        // 打印内存警告
        linuxOvercommitMemoryWarning();
    #endif
        // 从 AOF 文件或者 RDB 文件中载入数据
        loadDataFromDisk();
        // 启动集群？
        if (server.cluster_enabled) {
            if (verifyClusterConfigWithData() == REDIS_ERR) {
                redisLog(REDIS_WARNING,
                    "You can't have keys in a DB different than DB 0 when in "
                    "Cluster mode. Exiting.");
                exit(1);
            }
        }
        // 打印 TCP 端口
        if (server.ipfd_count > 0)
            redisLog(REDIS_NOTICE,"The server is now ready to accept connections on port %d", server.port);
        // 打印本地套接字端口
        if (server.sofd > 0)
            redisLog(REDIS_NOTICE,"The server is now ready to accept connections at %s", server.unixsocket);
    } else {
        sentinelIsRunning();
    }

    /* Warning the user about suspicious maxmemory setting. */
    // 检查不正常的 maxmemory 配置
    if (server.maxmemory > 0 && server.maxmemory < 1024*1024) {
        redisLog(REDIS_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);
    }

    // 运行事件处理器，一直到服务器关闭为止
    aeSetBeforeSleepProc(server.el,beforeSleep);
    aeMain(server.el);

    // 服务器关闭，停止事件循环
    aeDeleteEventLoop(server.el);

    return 0;
}

1、本地配置基本初始化

包括设置 server 运行的时区、设置哈希函数的随机种子。

    //设置本地时间
    setlocale(LC_COLLATE,"");
    zmalloc_enable_thread_safeness();
    zmalloc_set_oom_handler(redisOutOfMemoryHandler);
    srand(time(NULL)^getpid());
    gettimeofday(&tv,NULL);
    //设置随机数种子
    dictSetHashFunctionSeed(tv.tv_sec^tv.tv_usec^getpid());

2、检查哨兵模式

检查是不是以哨兵模式启动
/* Returns 1 if there is --sentinel among the arguments or if
 * argv[0] is exactly "redis-sentinel". */
int checkForSentinelMode(int argc, char **argv) {
    int j;

    if (strstr(argv[0],"redis-sentinel") != NULL) return 1;
    for (j = 1; j < argc; j++)
        if (!strcmp(argv[j],"--sentinel")) return 1;
    return 0;
}

    /* 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. */
    // 如果服务器以 Sentinel 模式启动，那么进行 Sentinel 功能相关的初始化
    // 并为要监视的主服务器创建一些相应的数据结构
    if (server.sentinel_mode) {
        initSentinelConfig();
        initSentinel();
    }

3、运行参数解析

解析options，加载配置文件

    // 检查用户是否指定了配置文件，或者配置选项
    if (argc >= 2) {
        int j = 1; /* First option to parse in argv[] */
        sds options = sdsempty();
        char *configfile = NULL;

        /* Handle special options --help and --version */
        // 处理特殊选项 -h 、-v 和 --test-memory
        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? */
        // 如果第一个参数（argv[1]）不是以 "--" 开头
        // 那么它应该是一个配置文件
        if (argv[j][0] != '-' || argv[j][1] != '-')
            configfile = argv[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. */
        // 对用户给定的其余选项进行分析，并将分析所得的字符串追加稍后载入的配置文件的内容之后
        // 比如 --port 6380 会被分析为 "port 6380\n"
        while(j != argc) {
            if (argv[j][0] == '-' && argv[j][1] == '-') {
                /* Option name */
                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++;
        } 
loadServerConfig(configfile,options);

4、初始化 server

初始化数据库数据结构和pool，网络交互初始化（线程初始化、工作队列初始化）

void initServer() {
    int j;

    // 设置信号处理函数
    signal(SIGHUP, SIG_IGN);
    signal(SIGPIPE, SIG_IGN);
    setupSignalHandlers();

    // 设置 syslog
    if (server.syslog_enabled) {
        openlog(server.syslog_ident, LOG_PID | LOG_NDELAY | LOG_NOWAIT,
            server.syslog_facility);
    }

    // 初始化并创建数据结构
    server.current_client = NULL;
    server.clients = listCreate();
    server.clients_to_close = listCreate();
    server.slaves = listCreate();
    server.monitors = 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;

    // 创建共享对象
    createSharedObjects();
    adjustOpenFilesLimit();
    server.el = aeCreateEventLoop(server.maxclients+REDIS_EVENTLOOP_FDSET_INCR);
    server.db = zmalloc(sizeof(redisDb)*server.dbnum);

    /* Open the TCP listening socket for the user commands. */
    // 打开 TCP 监听端口，用于等待客户端的命令请求
    if (server.port != 0 &&
        listenToPort(server.port,server.ipfd,&server.ipfd_count) == REDIS_ERR)
        exit(1);

    /* Open the listening Unix domain socket. */
    // 打开 UNIX 本地端口
    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) {
            redisLog(REDIS_WARNING, "Opening 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) {
        redisLog(REDIS_WARNING, "Configured to not listen anywhere, exiting.");
        exit(1);
    }

    /* Create the Redis databases, and initialize other internal state. */
    // 创建并初始化数据库结构
    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(&setDictType,NULL);
        server.db[j].watched_keys = dictCreate(&keylistDictType,NULL);
        server.db[j].eviction_pool = evictionPoolAlloc();
        server.db[j].id = j;
        server.db[j].avg_ttl = 0;
    }

    // 创建 PUBSUB 相关结构
    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;
    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.resident_set_size = 0;
    server.lastbgsave_status = REDIS_OK;
    server.aof_last_write_status = REDIS_OK;
    server.aof_last_write_errno = 0;
    server.repl_good_slaves_count = 0;
    updateCachedTime();

    /* Create the serverCron() time event, that's our main way to process
     * background operations. */
    // 为 serverCron() 创建时间事件
    if(aeCreateTimeEvent(server.el, 1, serverCron, NULL, NULL) == AE_ERR) {
        redisPanic("Can't create the serverCron time event.");
        exit(1);
    }

    /* Create an event handler for accepting new connections in TCP and Unix
     * domain sockets. */
    // 为 TCP 连接关联连接应答（accept）处理器
    // 用于接受并应答客户端的 connect() 调用
    for (j = 0; j < server.ipfd_count; j++) {
        if (aeCreateFileEvent(server.el, server.ipfd[j], AE_READABLE,
            acceptTcpHandler,NULL) == AE_ERR)
            {
                redisPanic(
                    "Unrecoverable error creating server.ipfd file event.");
            }
    }

    // 为本地套接字关联应答处理器
    if (server.sofd > 0 && aeCreateFileEvent(server.el,server.sofd,AE_READABLE,
        acceptUnixHandler,NULL) == AE_ERR) redisPanic("Unrecoverable error creating server.sofd file event.");

    /* Open the AOF file if needed. */
    // 如果 AOF 持久化功能已经打开，那么打开或创建一个 AOF 文件
    if (server.aof_state == REDIS_AOF_ON) {
        server.aof_fd = open(server.aof_filename,
                               O_WRONLY|O_APPEND|O_CREAT,0644);
        if (server.aof_fd == -1) {
            redisLog(REDIS_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. */
    // 对于 32 位实例来说，默认将最大可用内存限制在 3 GB
    if (server.arch_bits == 32 && server.maxmemory == 0) {
        redisLog(REDIS_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 = REDIS_MAXMEMORY_NO_EVICTION;
    }

    // 如果服务器以 cluster 模式打开，那么初始化 cluster
    if (server.cluster_enabled) clusterInit();

    // 初始化复制功能有关的脚本缓存
    replicationScriptCacheInit();

    // 初始化脚本系统
    scriptingInit();

    // 初始化慢查询功能
    slowlogInit();

    // 初始化 BIO 系统
    bioInit();
}

5、执行事件驱动框架（Reactor模型）

   // 运行事件处理器，一直到服务器关闭为止
    aeSetBeforeSleepProc(server.el,beforeSleep);
    //事件处理的入口函数
    aeMain(server.el);

    // 服务器关闭，停止事件循环
    aeDeleteEventLoop(server.el);