main_base = event_init();

stats_init();

/*** Global stats.*/
struct stats {pthread_mutex_t mutex;unsigned int  curr_items;unsigned int  total_items;uint64_t      curr_bytes;unsigned int  curr_conns;unsigned int  total_conns;uint64_t      rejected_conns;uint64_t      malloc_fails;unsigned int  reserved_fds;unsigned int  conn_structs;uint64_t      get_cmds;uint64_t      set_cmds;uint64_t      touch_cmds;uint64_t      get_hits;uint64_t      get_misses;uint64_t      touch_hits;uint64_t      touch_misses;uint64_t      evictions;uint64_t      reclaimed;time_t        started;          /* when the process was started */bool          accepting_conns;  /* whether we are currently accepting */uint64_t      listen_disabled_num;unsigned int  hash_power_level; /* Better hope it's not over 9000 */uint64_t      hash_bytes;       /* size used for hash tables */bool          hash_is_expanding; /* If the hash table is being expanded */uint64_t      expired_unfetched; /* items reclaimed but never touched */uint64_t      evicted_unfetched; /* items evicted but never touched */bool          slab_reassign_running; /* slab reassign in progress */uint64_t      slabs_moved;       /* times slabs were moved around */uint64_t      lru_crawler_starts; /* Number of item crawlers kicked off */bool          lru_crawler_running; /* crawl in progress */uint64_t      lru_maintainer_juggles; /* number of LRU bg pokes */
};

assoc_init(settings.hashpower_init);

conn_init()

/** Initializes the connections array. We don't actually allocate connection* structures until they're needed, so as to avoid wasting memory when the* maximum connection count is much higher than the actual number of* connections.** This does end up wasting a few pointers' worth of memory for FDs that are* used for things other than connections, but that's worth it in exchange for* being able to directly index the conns array by FD.*/
static void conn_init(void) {/* We're unlikely to see an FD much higher than maxconns. */int next_fd = dup(1);int headroom = 10;      /* account for extra unexpected open FDs */struct rlimit rl;max_fds = settings.maxconns + headroom + next_fd;/* But if possible, get the actual highest FD we can possibly ever see. */if (getrlimit(RLIMIT_NOFILE, &rl) == 0) {max_fds = rl.rlim_max;} else {fprintf(stderr, "Failed to query maximum file descriptor; ""falling back to maxconns\n");}close(next_fd);if ((conns = calloc(max_fds, sizeof(conn *))) == NULL) {fprintf(stderr, "Failed to allocate connection structures\n");/* This is unrecoverable so bail out early. */exit(1);}
}

    while (++i < MAX_NUMBER_OF_SLAB_CLASSES-1 && size <= settings.item_size_max / factor) {/* Make sure items are always n-byte aligned */if (size % CHUNK_ALIGN_BYTES)size += CHUNK_ALIGN_BYTES - (size % CHUNK_ALIGN_BYTES);slabclass[i].size = size;slabclass[i].perslab = settings.item_size_max / slabclass[i].size;size *= factor;if (settings.verbose > 1) {fprintf(stderr, "slab class %3d: chunk size %9u perslab %7u\n",i, slabclass[i].size, slabclass[i].perslab);}}

memcached_thread_init(settings.num_threads, main_base);

clock_handler(0, 0, 0);

    /* enter the event loop */if (event_base_loop(main_base, 0) != 0) {retval = EXIT_FAILURE;}

server_sockets——>
server_socket——>
conn_new——>
event_handler——>
drive_machine——>
try_read_command（这里会判定，是文本协议还是二进制协议）

void stop_assoc_maintenance_thread() {mutex_lock(&maintenance_lock);do_run_maintenance_thread = 0;pthread_cond_signal(&maintenance_cond);mutex_unlock(&maintenance_lock);/* Wait for the maintenance thread to stop */pthread_join(maintenance_tid, NULL);
}