Redis 内存管理与事件处理

void *zmalloc(size_t size) {
    // 多申请的一部分内存用于存储当前分配了多少自己的内存
    void *ptr = malloc(size+PREFIX_SIZE);
 
    if (!ptr) zmalloc_oom_handler(size);
#ifdef HAVE_MALLOC_SIZE
    update_zmalloc_stat_alloc(zmalloc_size(ptr));
    return ptr;
#else
    *((size_t*)ptr) = size;
    // 内存分配统计
    update_zmalloc_stat_alloc(size+PREFIX_SIZE);
    return (char*)ptr+PREFIX_SIZE;
#endif
}

void initServer(void) {
    int j;
 
    // 设置信号对应的处理函数
    signal(SIGHUP, SIG_IGN);
    signal(SIGPIPE, SIG_IGN);
    setupSignalHandlers();
    ...
 
    createSharedObjects();
    adjustOpenFilesLimit();
    // 创建事件循环机制，及调用epoll_create创建epollfd用于事件监听
    server.el = aeCreateEventLoop(server.maxclients+CONFIG_FDSET_INCR);
    server.db = zmalloc(sizeof(redisDb)*server.dbnum);
 
    /* Open the TCP listening socket for the user commands. */
    // 创建监听服务端口，socket/bind/listen
    if (server.port != 0 &&
        listenToPort(server.port,server.ipfd,&server.ipfd_count) == C_ERR)
        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(&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;
    }
    ...
 
    /* Create the serverCron() time event, that's our main way to process
     * background operations. 创建定时事件 */
    if(aeCreateTimeEvent(server.el, 1, serverCron, NULL, NULL) == AE_ERR) {
        serverPanic("Can't create the serverCron time event.");
        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.");
            }
    }
    // 将事件加入到事件机制中，调用链为 aeCreateFileEvent/aeApiAddEvent/epoll_ctl
    if (server.sofd > 0 && aeCreateFileEvent(server.el,server.sofd,AE_READABLE,
        acceptUnixHandler,NULL) == AE_ERR) serverPanic("Unrecoverable error creating server.sofd file event.");
 
    /* 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);
        }
    }
 
    ...
}