redis源码分析----main函数

int main(int argc, char **argv) {    struct timeval tv;    /* We need to initialize our libraries, and the server configuration. */#ifdef INIT_SETPROCTITLE_REPLACEMENT    spt_init(argc, argv);#endif    setlocale(LC_COLLATE,"");/* 设置线程安全标志 */    zmalloc_enable_thread_safeness();/* 设置内存管理函数 */    zmalloc_set_oom_handler(redisOutOfMemoryHandler);/* 设置随机数种子 */    srand(time(NULL)^getpid());/* 得到当前时间，下面设置哈希函数种子时会用到 */    gettimeofday(&tv,NULL);/* 设置哈希函数种子 */    dictSetHashFunctionSeed(tv.tv_sec^tv.tv_usec^getpid());/* 检查是否开启哨兵 */    server.sentinel_mode = checkForSentinelMode(argc,argv);/* 初始化server变量 */    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. */    if (server.sentinel_mode) {/* 设置哨兵相关配置，目前只有一个port选项，默认值为26379 */        initSentinelConfig();/*该函数把普通的命令删除，然后将哨兵相关参数设置到server.commands中，然后初始化哨兵相关的数据结构 */        initSentinel();    }    if (argc >= 2) {        int 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? *//* 分析得到配置文件名 */        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);        }/* getAbsolutePath该函数的目的是得到配置文件的绝对路径 */        if (configfile) server.configfile = getAbsolutePath(configfile);/* 清空server.saveparams，该数据成员存储的是save规则的内容，save规则模式如下：     秒  最少写次数save 900 1900秒内，最少执行一次写操作save 300 10300秒内，最少执行十次写操作save 60 1000060秒内，最少执行一千次写操作*/        resetServerSaveParams();/* 分析配置文件，options是当命令行参数个数大于2时，得到的*/        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");    }/* 判断是否开启守护进程模式 */    if (server.daemonize) daemonize();/* 该函数主要是注册信号处理函数，并初始化一些选项，这些选项之所以在此初始化，是因为这些选项依赖于配置文件的内容 */    initServer();/* 如果打开了守护进程选项，则在配置选项pidfile指定的文件中写入该进程的pid */    if (server.daemonize) createPidFile();/* 以下两个函数用作打印提示信息，在server.daemonize == 1时，该函数相当于什么都不做 */    redisSetProcTitle(argv[0]);    redisAsciiArt();    if (!server.sentinel_mode) {        /* Things not needed when running in Sentinel mode. */        redisLog(REDIS_WARNING,"Server started, Redis version " REDIS_VERSION);    #ifdef __linux__/* 读取/proc/sys/vm/overcommit_memory文件内容，该文件指定了内核针对内存分配的策略，其值可以是0、1、2：0 表示内核将检查是否有足够的可用内容供应用程序进程使用；如果有，内存申请允许；否则，内存申请失败，并把错误返回给应用进程1 表示内核允许分配所有的物理内存，而不管当前的内存状态如何2 表示内核允许分配超过所有物理内核和交换空间总和的内存 */        linuxMemoryWarnings();    #endif        checkTcpBacklogSettings();/* 通过AOF或RDB方式从磁盘读取持久化的数据 */        loadDataFromDisk();        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 {        sentinelIsRunning();    }    /* 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);    }    aeSetBeforeSleepProc(server.el,beforeSleep);/* redis核心函数 */    aeMain(server.el);    aeDeleteEventLoop(server.el);    return 0;}