void *IOThreadEntryPoint(void *arg) {
    iojob *j;
    listNode *ln;
    REDIS_NOTUSED(arg);

    pthread_detach(pthread_self());
    while(1) {
        /* Get a new job to process */
        lockThreadedIO();
        if (listLength(server.io_newjobs) == 0) {
            /* No new jobs in queue, exit. */
            redisLog(REDIS_DEBUG,"Thread %ld exiting, nothing to do",
                (long) pthread_self());
            server.io_active_threads--;
            unlockThreadedIO();
            return NULL;
        }
        ln = listFirst(server.io_newjobs);
        j = ln->value;
        listDelNode(server.io_newjobs,ln);
        /* Add the job in the processing queue */
        j->thread = pthread_self();
        listAddNodeTail(server.io_processing,j);
        ln = listLast(server.io_processing); /* We use ln later to remove it */
        unlockThreadedIO();
        redisLog(REDIS_DEBUG,"Thread %ld got a new job (type %d): %p about key '%s'",
            (long) pthread_self(), j->type, (void*)j, (char*)j->key->ptr);

        /* Process the Job */
        if (j->type == REDIS_IOJOB_LOAD) {
            vmpointer *vp = (vmpointer*)j->id;
            j->val = vmReadObjectFromSwap(j->page,vp->vtype);
        } else if (j->type == REDIS_IOJOB_PREPARE_SWAP) {
            j->pages = rdbSavedObjectPages(j->val);
        } else if (j->type == REDIS_IOJOB_DO_SWAP) {
            if (vmWriteObjectOnSwap(j->val,j->page) == REDIS_ERR)
                j->canceled = 1;
        }

        /* Done: insert the job into the processed queue */
        redisLog(REDIS_DEBUG,"Thread %ld completed the job: %p (key %s)",
            (long) pthread_self(), (void*)j, (char*)j->key->ptr);

        lockThreadedIO();
        listDelNode(server.io_processing,ln);
        listAddNodeTail(server.io_processed,j);
        unlockThreadedIO();

        /* Signal the main thread there is new stuff to process */
        redisAssert(write(server.io_ready_pipe_write,"x",1) == 1);
    }
    return NULL; /* never reached */
}

/* Preload keys needed to execute the entire MULTI/EXEC block.
 *
 * This function is called by blockClientOnSwappedKeys when EXEC is issued,
 * and will block the client when any command requires a swapped out value. */
void execBlockClientOnSwappedKeys(redisClient *c, struct redisCommand *cmd, int argc, robj **argv) {
    int i, margc;
    struct redisCommand *mcmd;
    robj **margv;
    REDIS_NOTUSED(cmd);
    REDIS_NOTUSED(argc);
    REDIS_NOTUSED(argv);

    if (!(c->flags & REDIS_MULTI)) return;
    for (i = 0; i < c->mstate.count; i++) {
        mcmd = c->mstate.commands[i].cmd;
        margc = c->mstate.commands[i].argc;
        margv = c->mstate.commands[i].argv;

        if (mcmd->vm_preload_proc != NULL) {
            mcmd->vm_preload_proc(c,mcmd,margc,margv);
        } else {
            waitForMultipleSwappedKeys(c,mcmd,margc,margv);
        }
    }
}

int showThroughput(struct aeEventLoop *eventLoop, long long id, void *clientData) {
    REDIS_NOTUSED(eventLoop);
    REDIS_NOTUSED(id);
    REDIS_NOTUSED(clientData);

    if (config.liveclients == 0) {
        fprintf(stderr,"All clients disconnected... aborting.\n");
        exit(1);
    }
    if (config.csv) return 250;
    if (config.idlemode == 1) {
        printf("clients: %d\r", config.liveclients);
        fflush(stdout);
	return 250;
    }
    float dt = (float)(mstime()-config.start)/1000.0;
    float rps = (float)config.requests_finished/dt;
    printf("%s: %.2f\r", config.title, rps);
    fflush(stdout);
    return 250; /* every 250ms */
}

/* Behaves as posix, works without ifdefs, makes compiler happy */
int sigaction(int sig, struct sigaction *in, struct sigaction *out) {
    REDIS_NOTUSED(out);

    /* When the SA_SIGINFO flag is set in sa_flags then sa_sigaction
    * is used. Otherwise, sa_handler is used */
    if (in->sa_flags & SA_SIGINFO) {
        signal(sig, in->sa_sigaction);
    } else {
        signal(sig, in->sa_handler);
    }
    return 0;
}

static void writeHandler(aeEventLoop *el, int fd, void *privdata, int mask) {
    client c = privdata;
    REDIS_NOTUSED(el);
    REDIS_NOTUSED(fd);
    REDIS_NOTUSED(mask);

    /* Initialize request when nothing was written. */
    if (c->written == 0) {
        /* Enforce upper bound to number of requests. */
        if (config.requests_issued++ >= config.requests) {
            freeClient(c);
            return;
        }

        /* Really initialize: randomize keys and set start time. */
        if (config.randomkeys) randomizeClientKey(c);
        c->start = ustime();
        c->latency = -1;
    }

    if (sdslen(c->obuf) > c->written) {
        void *ptr = c->obuf+c->written;
#ifdef _WIN32
        int nwritten = send(c->context->fd,ptr,sdslen(c->obuf)-c->written, 0);
#else
        int nwritten = write(c->context->fd,ptr,sdslen(c->obuf)-c->written);
#endif
        if (nwritten == -1) {
            if (errno != EPIPE)
                fprintf(stderr, "Writing to socket: %s\n", strerror(errno));
            freeClient(c);
            return;
        }
        c->written += nwritten;
        if (sdslen(c->obuf) == c->written) {
            aeDeleteFileEvent(config.el,c->context->fd,AE_WRITABLE);
            aeCreateFileEvent(config.el,c->context->fd,AE_READABLE,readHandler,c);
        }
    }
}

static void readHandler(aeEventLoop *el, int fd, void *privdata, int mask) {
    client c = privdata;
    void *reply = NULL;
    REDIS_NOTUSED(el);
    REDIS_NOTUSED(fd);
    REDIS_NOTUSED(mask);

    /* Calculate latency only for the first read event. This means that the
     * server already sent the reply and we need to parse it. Parsing overhead
     * is not part of the latency, so calculate it only once, here. */
    if (c->latency < 0) c->latency = ustime()-(c->start);

    if (redisBufferRead(c->context) != REDIS_OK) {
        fprintf(stderr,"Error: %s\n",c->context->errstr);
        exit(1);
    } else {
        while(c->pending) {
            if (redisGetReply(c->context,&reply) != REDIS_OK) {
                fprintf(stderr,"Error: %s\n",c->context->errstr);
                exit(1);
            }
            if (reply != NULL) {
                if (reply == (void*)REDIS_REPLY_ERROR) {
                    fprintf(stderr,"Unexpected error reply, exiting...\n");
                    exit(1);
                }

                freeReplyObject(reply);

                if (config.requests_finished < config.requests)
                    config.latency[config.requests_finished++] = c->latency;
                c->pending--;
                if (c->pending == 0) clientDone(c);
            } else {
                break;
            }
        }
    }
}

void readFromSlave(aeEventLoop *el, int fd, void *privdata, int mask){
	REDIS_NOTUSED(el);
	REDIS_NOTUSED(mask);
	char rdata[MAX_READ];
	int nread = readData(el, fd, rdata, MAX_READ);
	if(nread <= 0 )
	{
		return;
	}
	if(nread == 6){
		rdata[6]= 0;
		char *sync = "SYNC\r\n";
		if(strcmp(sync, rdata) == 0){
			log4c_category_log(mycat, LOG4C_PRIORITY_INFO, "sync start");
			state = SYNC_START_STATE;
		}		
	}
	int wr = writeData(el, master_fd, rdata, nread);
	if(-1 == wr)
	{
		log4c_category_log(mycat, LOG4C_PRIORITY_ERROR, "write to master failed error %d, at line %d in file %s",  errno,  __LINE__, __FILE__);
	}
}

void luaMaskCountHook(lua_State *lua, lua_Debug *ar) {
    long long elapsed;
    REDIS_NOTUSED(ar);
    REDIS_NOTUSED(lua);

    elapsed = mstime() - server.lua_time_start;
    if (elapsed >= server.lua_time_limit && server.lua_timedout == 0) {
        redisLog(REDIS_WARNING,"Lua slow script detected: still in execution after %lld milliseconds. You can try killing the script using the SCRIPT KILL command.",elapsed);
        server.lua_timedout = 1;
        /* Once the script timeouts we reenter the event loop to permit others
         * to call SCRIPT KILL or SHUTDOWN NOSAVE if needed. For this reason
         * we need to mask the client executing the script from the event loop.
         * If we don't do that the client may disconnect and could no longer be
         * here when the EVAL command will return. */
         aeDeleteFileEvent(server.el, server.lua_caller->fd, AE_READABLE);
    }
    if (server.lua_timedout) processEventsWhileBlocked();
    if (server.lua_kill) {
        redisLog(REDIS_WARNING,"Lua script killed by user with SCRIPT KILL.");
        lua_pushstring(lua,"Script killed by user with SCRIPT KILL...");
        lua_error(lua);
    }
}

static void ctrlc(int sig) {
    REDIS_NOTUSED(sig);

    if (config.idlemode) {
        exit(1);
    } else {
        config.ctrlc++;
        if (config.ctrlc == 1) {
            config.done = 1;
            printf("\nWaiting for pending requests to complete...\n");
        } else {
            printf("\nForcing exit...\n");
            exit(1);
        }
    }
}

int pthread_join(pthread_t thread, void **value_ptr)  {
    int result;
    HANDLE h = OpenThread(SYNCHRONIZE, FALSE, thread);
    REDIS_NOTUSED(value_ptr);

    switch (WaitForSingleObject(h, INFINITE)) {
            case WAIT_OBJECT_0:
                    result = 0;
            case WAIT_ABANDONED:
                    result = EINVAL;
            default:
                    result = GetLastError();
    }

    CloseHandle(h);
    return result;
}

int *getKeysUsingCommandTable(struct redisCommand *cmd,robj **argv, int argc, int *numkeys) {
    int j, i = 0, last, *keys;
    REDIS_NOTUSED(argv);

    if (cmd->firstkey == 0) {
        *numkeys = 0;
        return NULL;
    }
    last = cmd->lastkey;
    if (last < 0) last = argc+last;
    keys = zmalloc(sizeof(int)*((last - cmd->firstkey)+1));
    for (j = cmd->firstkey; j <= last; j += cmd->keystep) {
        redisAssert(j < argc);
        keys[i++] = j;
    }
    *numkeys = i;
    return keys;
}

/* Helper function to extract keys from the following commands:
 * EVAL <script> <num-keys> <key> <key> ... <key> [more stuff]
 * EVALSHA <script> <num-keys> <key> <key> ... <key> [more stuff] */
int *evalGetKeys(struct redisCommand *cmd, robj **argv, int argc, int *numkeys) {
    int i, num, *keys;
    REDIS_NOTUSED(cmd);

    num = atoi(argv[2]->ptr);
    /* Sanity check. Don't return any key if the command is going to
     * reply with syntax error. */
    if (num > (argc-3)) {
        *numkeys = 0;
        return NULL;
    }

    keys = zmalloc(sizeof(int)*num);
    *numkeys = num;

    /* Add all key positions for argv[3...n] to keys[] */
    for (i = 0; i < num; i++) keys[i] = 3+i;

    return keys;
}

int pthread_create(pthread_t *thread, const void *unused,
           void *(*start_routine)(void*), void *arg) {
    HANDLE h;
    thread_params *params = (thread_params *)malloc(sizeof(thread_params));
    REDIS_NOTUSED(unused);

    params->func = start_routine;
    params->arg  = arg;

    h =(HANDLE) _beginthreadex(NULL,  /* Security not used */
                               REDIS_THREAD_STACK_SIZE, /* Set custom stack size */
                               win32_proxy_threadproc,  /* calls win32 stdcall proxy */
                               params, /* real threadproc is passed as paremeter */
                               STACK_SIZE_PARAM_IS_A_RESERVATION,  /* reserve stack */
                               thread /* returned thread id */
                );

    if (!h)
        return errno;

    CloseHandle(h);
    return 0;
}

int pthread_cond_init(pthread_cond_t *cond, const void *unused) {
        REDIS_NOTUSED(unused);
        cond->waiters = 0;
        cond->was_broadcast = 0;

        InitializeCriticalSection(&cond->waiters_lock);

        cond->sema = CreateSemaphore(NULL, 0, LONG_MAX, NULL);
        if (!cond->sema) {
            errno = GetLastError();
            return -1;
        }

        cond->continue_broadcast = CreateEvent(NULL,    /* security */
                                FALSE,                  /* auto-reset */
                                FALSE,                  /* not signaled */
                                NULL);                  /* name */
        if (!cond->continue_broadcast) {
            errno = GetLastError();
            return -1;
        }

        return 0;
}

void readFromMaster(aeEventLoop *el, int fd, void *privdata, int mask) {
	REDIS_NOTUSED(el);
	REDIS_NOTUSED(mask);
	int nread;
	char rdata[MAX_READ];
	char *p = rdata;
	switch(state){
		case SYNC_START_STATE:{	 
			while(1){
				nread = readData(el, fd, p,1);
				if(nread < 0){
					return;
				}
				else if(nread == 0){
					continue;
				}
	
				int wr = writeData(el, client_fd, p, 1);
				if(-1 == wr)
				{
					return;
				}
				if(*p == '\n' && p != rdata) break;
				if(*p != '\n') p++;
			}
			*p = '\0';
			if(rdata[0] == '-'){
				log4c_category_log(mycat, LOG4C_PRIORITY_ERROR, "sync with master failed at line %d in file %s",   __LINE__, __FILE__);
				exit(1);
			}
			bulk_size = strtoull(rdata + 1, 0, 10);
			log4c_category_log(mycat, LOG4C_PRIORITY_INFO, "bulk size %llu, at line %d in file %s",  bulk_size,  __LINE__, __FILE__);
			state = SYNC_STATE;
			break;
		} 
		case SYNC_STATE:{ 
			long long int all_read =0;
			long long int all_write =0;
			while(bulk_size){
				nread = readData(el, fd, rdata, (bulk_size > MAX_READ) ? MAX_READ:bulk_size);
				if(nread < 0 )
				{
					return;
				}
				else if (nread == 0){
					continue;
				}
				else{
					all_read += nread;
				}
				int wr = writeData(el, client_fd, rdata,nread);
				if(-1 == wr)
				{
					log4c_category_log(mycat, LOG4C_PRIORITY_ERROR, "write to payload failed error %d, at line %d in file %s",  errno,  __LINE__, __FILE__);
					return;
				}
				else{
					all_write += wr;
				}
				bulk_size -= nread;
			}
			state = RUNNING_STATE;		
			log4c_category_log(mycat, LOG4C_PRIORITY_INFO, "sync done");
			break;
		} 
		default:{ 
			nread = readData(el, fd, rdata, MAX_READ);
			if(nread > 0){
				struct WData wdata;
				wdata.len = nread;
				wdata.data= rdata; 
				if( state == RUNNING_STATE){
					processInputBuffer(el, &wdata);
					int wr = writeData(el, client_fd, wdata.data, wdata.len);
					if(-1 == wr)
					{
						return;
					}
				}
				else{
					if(nread > 9 && nread < 100)
					{
						if(!strncmp(rdata,"+CONTINUE",9) || !strncmp(rdata,"+FULLRESYNC",11)){
		
							log4c_category_log(mycat, LOG4C_PRIORITY_INFO, "sync start");
							state = SYNC_START_STATE;
						}
					}
					int wr = writeData(el, client_fd, wdata.data, wdata.len);
					if(-1 == wr)
					{
						return;
					}
		
				}
			}
			break; 
		} 
	}

//.........这里部分代码省略.........

/* Noop in windows */
int pthread_detach (pthread_t thread) {
    REDIS_NOTUSED(thread);
    return 0; /* noop */
}

void sendReplyToClientWritev(aeEventLoop *el, int fd, void *privdata, int mask)
{
    redisClient *c = privdata;
    int nwritten = 0, totwritten = 0, objlen, willwrite;
    robj *o;
    struct iovec iov[REDIS_WRITEV_IOVEC_COUNT];
    int offset, ion = 0;
    REDIS_NOTUSED(el);
    REDIS_NOTUSED(mask);

    listNode *node;
    while (listLength(c->reply)) {
        offset = c->sentlen;
        ion = 0;
        willwrite = 0;

        /* fill-in the iov[] array */
        for(node = listFirst(c->reply); node; node = listNextNode(node)) {
            o = listNodeValue(node);
            objlen = sdslen(o->ptr);

            if (totwritten + objlen - offset > REDIS_MAX_WRITE_PER_EVENT)
                break;

            if(ion == REDIS_WRITEV_IOVEC_COUNT)
                break; /* no more iovecs */

            iov[ion].iov_base = ((char*)o->ptr) + offset;
            iov[ion].iov_len = objlen - offset;
            willwrite += objlen - offset;
            offset = 0; /* just for the first item */
            ion++;
        }

        if(willwrite == 0)
            break;

        /* write all collected blocks at once */
        if((nwritten = writev(fd, iov, ion)) < 0) {
            if (errno != EAGAIN) {
                redisLog(REDIS_VERBOSE,
                         "Error writing to client: %s", strerror(errno));
                freeClient(c);
                return;
            }
            break;
        }

        totwritten += nwritten;
        offset = c->sentlen;

        /* remove written robjs from c->reply */
        while (nwritten && listLength(c->reply)) {
            o = listNodeValue(listFirst(c->reply));
            objlen = sdslen(o->ptr);

            if(nwritten >= objlen - offset) {
                listDelNode(c->reply, listFirst(c->reply));
                nwritten -= objlen - offset;
                c->sentlen = 0;
            } else {
                /* partial write */
                c->sentlen += nwritten;
                break;
            }
            offset = 0;
        }
    }

    if (totwritten > 0)
        c->lastinteraction = time(NULL);

    if (listLength(c->reply) == 0) {
        c->sentlen = 0;
        aeDeleteFileEvent(server.el,c->fd,AE_WRITABLE);
    }
}

void sendReplyToClient(aeEventLoop *el, int fd, void *privdata, int mask) {
    redisClient *c = privdata;
    int nwritten = 0, totwritten = 0, objlen;
    robj *o;
    REDIS_NOTUSED(el);
    REDIS_NOTUSED(mask);

    /* Use writev() if we have enough buffers to send */
    if (!server.glueoutputbuf &&
        listLength(c->reply) > REDIS_WRITEV_THRESHOLD &&
        !(c->flags & REDIS_MASTER))
    {
        sendReplyToClientWritev(el, fd, privdata, mask);
        return;
    }

    while(listLength(c->reply)) {
        if (server.glueoutputbuf && listLength(c->reply) > 1)
            glueReplyBuffersIfNeeded(c);

        o = listNodeValue(listFirst(c->reply));
        objlen = sdslen(o->ptr);

        if (objlen == 0) {
            listDelNode(c->reply,listFirst(c->reply));
            continue;
        }

        if (c->flags & REDIS_MASTER) {
            /* Don't reply to a master */
            nwritten = objlen - c->sentlen;
        } else {
            nwritten = write(fd, ((char*)o->ptr)+c->sentlen, objlen - c->sentlen);
            if (nwritten <= 0) break;
        }
        c->sentlen += nwritten;
        totwritten += nwritten;
        /* If we fully sent the object on head go to the next one */
        if (c->sentlen == objlen) {
            listDelNode(c->reply,listFirst(c->reply));
            c->sentlen = 0;
        }
        /* Note that we avoid to send more thank REDIS_MAX_WRITE_PER_EVENT
         * bytes, in a single threaded server it's a good idea to serve
         * other clients as well, even if a very large request comes from
         * super fast link that is always able to accept data (in real world
         * scenario think about 'KEYS *' against the loopback interfae) */
        if (totwritten > REDIS_MAX_WRITE_PER_EVENT) break;
    }
    if (nwritten == -1) {
        if (errno == EAGAIN) {
            nwritten = 0;
        } else {
            redisLog(REDIS_VERBOSE,
                "Error writing to client: %s", strerror(errno));
            freeClient(c);
            return;
        }
    }
    if (totwritten > 0) c->lastinteraction = time(NULL);
    if (listLength(c->reply) == 0) {
        c->sentlen = 0;
        aeDeleteFileEvent(server.el,c->fd,AE_WRITABLE);
    }
}

// 这其实是一个回调函数，会作为参数传入另外一个函数中
static void readHandler(aeEventLoop *el, int fd, void *privdata, int mask) {
    client c = privdata;
    void *reply = NULL;
    REDIS_NOTUSED(el);
    REDIS_NOTUSED(fd);
    REDIS_NOTUSED(mask);

    /* Calculate latency only for the first read event. This means that the
     * server already sent the reply and we need to parse it. Parsing overhead
     * is not part of the latency, so calculate it only once, here. */
    // 计算延时，然后比较延时，取得第一个read的event事件
    if (c->latency < 0) c->latency = ustime()-(c->start);

    if (redisBufferRead(c->context) != REDIS_OK) {
        // 首先判断是否能读
        fprintf(stderr,"Error: %s\n",c->context->errstr);
        exit(1);
    } else {
        while(c->pending) {
            if (redisGetReply(c->context,&reply) != REDIS_OK) {
                fprintf(stderr,"Error: %s\n",c->context->errstr);
                exit(1);
            }
            if (reply != NULL) {
                if (reply == (void*)REDIS_REPLY_ERROR) {
                    // 如果获取reply回复出错，也会直接退出
                    fprintf(stderr,"Unexpected error reply, exiting...\n");
                    exit(1);
                }

                freeReplyObject(reply);
                /* This is an OK for prefix commands such as auth and select.*/
                if (c->prefix_pending > 0) {
                    c->prefix_pending--;
                    // 执行到这里，请求已经执行成功，等待的请求数-1
                    c->pending--;
                    /* Discard prefix commands on first response.*/
                    if (c->prefixlen > 0) {
                        size_t j;
                        sdsrange(c->obuf, c->prefixlen, -1);
                        /* We also need to fix the pointers to the strings
                        * we need to randomize. */
                        for (j = 0; j < c->randlen; j++)
                            c->randptr[j] -= c->prefixlen;
                        c->prefixlen = 0;
                    }
                    continue;
                }

                if (config.requests_finished < config.requests)
                    config.latency[config.requests_finished++] = c->latency;
                c->pending--;
                // 全部处理完毕，调用客户端done完成后的方法
                if (c->pending == 0) {
                    clientDone(c);
                    break;
                }
            } else {
                break;
            }
        }
    }
}

void syncWithMaster(aeEventLoop *el, int fd, void *privdata, int mask) {
    char tmpfile[256], *err;
    int dfd, maxtries = 5;
    int sockerr = 0;
    socklen_t errlen = sizeof(sockerr);
    REDIS_NOTUSED(el);
    REDIS_NOTUSED(privdata);
    REDIS_NOTUSED(mask);

    /* If this event fired after the user turned the instance into a master
     * with SLAVEOF NO ONE we must just return ASAP. */
    if (server.repl_state == REDIS_REPL_NONE) {
        close(fd);
        return;
    }

    /* Check for errors in the socket. */
    if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &sockerr, &errlen) == -1)
        sockerr = errno;
    if (sockerr) {
        aeDeleteFileEvent(server.el,fd,AE_READABLE|AE_WRITABLE);
        redisLog(REDIS_WARNING,"Error condition on socket for SYNC: %s",
            strerror(sockerr));
        goto error;
    }

    /* If we were connecting, it's time to send a non blocking PING, we want to
     * make sure the master is able to reply before going into the actual
     * replication process where we have long timeouts in the order of
     * seconds (in the meantime the slave would block). */
    if (server.repl_state == REDIS_REPL_CONNECTING) {
        redisLog(REDIS_NOTICE,"Non blocking connect for SYNC fired the event.");
        /* Delete the writable event so that the readable event remains
         * registered and we can wait for the PONG reply. */
        aeDeleteFileEvent(server.el,fd,AE_WRITABLE);
        server.repl_state = REDIS_REPL_RECEIVE_PONG;
        /* Send the PING, don't check for errors at all, we have the timeout
         * that will take care about this. */
        syncWrite(fd,"PING\r\n",6,100);
        return;
    }

    /* Receive the PONG command. */
    if (server.repl_state == REDIS_REPL_RECEIVE_PONG) {
        char buf[1024];

        /* Delete the readable event, we no longer need it now that there is
         * the PING reply to read. */
        aeDeleteFileEvent(server.el,fd,AE_READABLE);

        /* Read the reply with explicit timeout. */
        buf[0] = '\0';
        if (syncReadLine(fd,buf,sizeof(buf),
            server.repl_syncio_timeout*1000) == -1)
        {
            redisLog(REDIS_WARNING,
                "I/O error reading PING reply from master: %s",
                strerror(errno));
            goto error;
        }

        /* We don't care about the reply, it can be +PONG or an error since
         * the server requires AUTH. As long as it replies correctly, it's
         * fine from our point of view. */
        if (buf[0] != '-' && buf[0] != '+') {
            redisLog(REDIS_WARNING,"Unexpected reply to PING from master.");
            goto error;
        } else {
            redisLog(REDIS_NOTICE,
                "Master replied to PING, replication can continue...");
        }
    }

    /* AUTH with the master if required. */
    if(server.masterauth) {
        err = sendSynchronousCommand(fd,"AUTH",server.masterauth,NULL);
        if (err) {
            redisLog(REDIS_WARNING,"Unable to AUTH to MASTER: %s",err);
            sdsfree(err);
            goto error;
        }
    }

    /* Set the slave port, so that Master's INFO command can list the
     * slave listening port correctly. */
    {
        sds port = sdsfromlonglong(server.port);
        err = sendSynchronousCommand(fd,"REPLCONF","listening-port",port,
                                         NULL);
        sdsfree(port);
        /* Ignore the error if any, not all the Redis versions support
         * REPLCONF listening-port. */
        if (err) {
            redisLog(REDIS_NOTICE,"(non critical): Master does not understand REPLCONF listening-port: %s", err);
            sdsfree(err);
        }
    }

    /* Issue the SYNC command */
    if (syncWrite(fd,"SYNC\r\n",6,server.repl_syncio_timeout*1000) == -1) {
//.........这里部分代码省略.........