redis3.0.7源码阅读(十三)main函数

灰太狼 2022-07-13 11:59 79阅读 0赞

版本：3.0.7

源码：redis.c

/*
     * 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
        setlocale(LC_COLLATE,"");
        zmalloc_enable_thread_safeness();
        zmalloc_set_oom_handler(redisOutOfMemoryHandler);
        srand(time(NULL)^getpid());
        gettimeofday(&tv,NULL);
        dictSetHashFunctionSeed(tv.tv_sec^tv.tv_usec^getpid());
    
        // 检查是否sentinel模式
        server.sentinel_mode = checkForSentinelMode(argc,argv);
    
        // 初始化服务器配置项
        initServerConfig();
    
        // 初始化sentinel
        /* 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();
        }
    
        if (argc >= 2) {
            int j = 1; /* First option to parse in argv[] */
            sds options = sdsempty();
            char *configfile = NULL;
    
            // 处理-v/--version/-h/--help/--test-memory
            /* 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);
                }
            }
    
            // 检查用户是否指定了配置文件，或者配置选项
            /* First argument is the config file name? */
            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. */
            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 (server.sentinel_mode && configfile && *configfile == '-') {
                redisLog(REDIS_WARNING,
                    "Sentinel config from STDIN not allowed.");
                redisLog(REDIS_WARNING,
                    "Sentinel needs config file on disk to save state.  Exiting...");
                exit(1);
            }
            if (configfile) server.configfile = getAbsolutePath(configfile);
            resetServerSaveParams();
    
            // 加载配置
            loadServerConfig(configfile,options);
            sdsfree(options);
        } 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");
        }
    
        // 守护模式
        if (server.daemonize) daemonize();
    
        // 初始化服务器
        initServer();
    
        // 守护模式创建PID文件
        if (server.daemonize) createPidFile();
    
        // 进程环境相关设置，设置名字
        redisSetProcTitle(argv[0]);
        
        // 打印 ASCII LOGO
        redisAsciiArt();
        
        // 检查内核backlog参数支持
        checkTcpBacklogSettings();
    
        if (!server.sentinel_mode) {
            /* Things not needed when running in Sentinel mode. */
            // 打印服务器启动成功
            redisLog(REDIS_WARNING,"Server started, Redis version " REDIS_VERSION);
        #ifdef __linux__
            // 检查内存分配策略，并打印警告
            linuxMemoryWarnings();
        #endif
            // 加载持久化文件
            loadDataFromDisk();
    
            // 如果是集群模式，检查加载的数据是否正确
            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);
                }
            }
            if (server.ipfd_count > 0)
                redisLog(REDIS_NOTICE,"The server is now ready to accept connections on port %d", server.port);
            if (server.sofd > 0)
                redisLog(REDIS_NOTICE,"The server is now ready to accept connections at %s", server.unixsocket);
        } else {
    
            // sentnel模式启动
            sentinelIsRunning();
        }
    
        // 设置的max内存小于1MB，提醒用户
        /* Warning the user about suspicious maxmemory setting. */
        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);
        }
    
        // 设置事件处理之前需要调用的函数
        aeSetBeforeSleepProc(server.el,beforeSleep);
        
        // 开始事件循环
        /*
         * 调用链举例
         * initServer()：aeCreateFileEvent注册acceptTcpHandler事件
         * 当客户端请求来临时：acceptTcpHandler->anetTcpAccept
         * 连接建立成功后，创建客户端：acceptCommonHandler->createClient
         * 创建客户端成功后：aeCreateFileEvent注册readQueryFromClient
         * 执行客户端命令：readQueryFromClient->processInputBuffer->processCommand
         * 在processCommand中通过lookupCommand找到命令对应的执行函数设置c->cmd，在一系列的判断后，调用call函数执行命令
         * call函数会执行c->cmd->proc(c)：在proc中会执行，比如proc是getCommand，在getCommand中会执行addReply函数
         * addReply函数是返回输出给客户端的底层调用，此函数会增加写事件sendReplyToClient到多路复用库中
         * 关于事件管理：每次执行1000次接收连接(acceptTcpHandler)，每次将所有的就绪事件都处理了(aeApiPoll函数)
         */ 
        aeMain(server.el);
    
        // 服务器关闭，停止事件循环
        aeDeleteEventLoop(server.el);
        return 0;
    }

原文出自：[http://blog.csdn.net/daiyudong2020/article/details/54237076][http_blog.csdn.net_daiyudong2020_article_details_54237076]

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[http_blog.csdn.net_daiyudong2020_article_details_54237076]: http://blog.csdn.net/daiyudong2020/article/details/54237076