void flushdbCommand(redisClient *c) {
server.dirty += dictSize(c->db->dict);
signalFlushedDb(c->db->id);
dictEmpty(c->db->dict);
dictEmpty(c->db->expires);
addReply(c,shared.ok);
}
void flushdbCommand(client *c) {
server.dirty += dictSize(c->db->dict);
signalFlushedDb(c->db->id);
dictEmpty(c->db->dict,NULL);
dictEmpty(c->db->expires,NULL);
if (server.cluster_enabled) slotToKeyFlush();
addReply(c,shared.ok);
}
/* FLUSHDB [ASYNC]
*
* Flushes the currently SELECTed Redis DB. */
void flushdbCommand(client *c) {
int flags;
if (getFlushCommandFlags(c,&flags) == C_ERR) return;
signalFlushedDb(c->db->id);
server.dirty += emptyDb(c->db->id,flags,NULL);
addReply(c,shared.ok);
}
void flushallCommand(redisClient *c) {
signalFlushedDb(-1);
server.dirty += emptyDb();
addReply(c,shared.ok);
if (server.bgsavechildpid != -1) {
kill(server.bgsavechildpid,SIGKILL);
rdbRemoveTempFile(server.bgsavechildpid);
}
if (server.ds_enabled)
dsFlushDb(-1);
else
rdbSave(server.dbfilename);
server.dirty++;
}
void flushallCommand(redisClient *c) {
signalFlushedDb(-1);
server.dirty += emptyDb();
addReply(c,shared.ok);
if (server.rdb_child_pid != -1) {
kill(server.rdb_child_pid,SIGUSR1);
rdbRemoveTempFile(server.rdb_child_pid);
}
if (server.saveparamslen > 0) {
/* Normally rdbSave() will reset dirty, but we don't want this here
* as otherwise FLUSHALL will not be replicated nor put into the AOF. */
int saved_dirty = server.dirty;
rdbSave(server.rdb_filename);
server.dirty = saved_dirty;
}
server.dirty++;
}
/* Asynchronously read the SYNC payload we receive from a master */
#define REPL_MAX_WRITTEN_BEFORE_FSYNC (1024*1024*8) /* 8 MB */
void readSyncBulkPayload(aeEventLoop *el, int fd, void *privdata, int mask) {
//读取master发过来的RDB大小以及文件内容保存到本地文件中；
//如果读取完毕，那么调用rdbLoad加载文件内容。并考虑重新启动startAppendOnly
char buf[4096];
ssize_t nread, readlen;
off_t left;
REDIS_NOTUSED(el);
REDIS_NOTUSED(privdata);
REDIS_NOTUSED(mask);
/* If repl_transfer_size == -1 we still have to read the bulk length
* from the master reply. */
if (server.repl_transfer_size == -1) {
if (syncReadLine(fd,buf,1024,server.repl_syncio_timeout*1000) == -1) {
redisLog(REDIS_WARNING,
"I/O error reading bulk count from MASTER: %s",
strerror(errno));
goto error;
}
if (buf[0] == '-') {
redisLog(REDIS_WARNING,
"MASTER aborted replication with an error: %s",
buf+1);
goto error;
} else if (buf[0] == '\0') {
/* At this stage just a newline works as a PING in order to take
* the connection live. So we refresh our last interaction
* timestamp. */
server.repl_transfer_lastio = server.unixtime;
return;
} else if (buf[0] != '$') {
redisLog(REDIS_WARNING,"Bad protocol from MASTER, the first byte is not '$', are you sure the host and port are right?");
goto error;
}
//先获取RDB文件大小。
server.repl_transfer_size = strtol(buf+1,NULL,10);
redisLog(REDIS_NOTICE,
"MASTER <-> SLAVE sync: receiving %ld bytes from master",
server.repl_transfer_size);
return;
}
/* Read bulk data */
left = server.repl_transfer_size - server.repl_transfer_read;
readlen = (left < (signed)sizeof(buf)) ? left : (signed)sizeof(buf);
nread = read(fd,buf,readlen);//读取一次，有且仅有的读取一次。每次可读事件就读一次。
if (nread <= 0) {
redisLog(REDIS_WARNING,"I/O error trying to sync with MASTER: %s",
(nread == -1) ? strerror(errno) : "connection lost");
replicationAbortSyncTransfer();
return;
}
server.repl_transfer_lastio = server.unixtime;
if (write(server.repl_transfer_fd,buf,nread) != nread) {//写到临时文件里面去。
redisLog(REDIS_WARNING,"Write error or short write writing to the DB dump file needed for MASTER <-> SLAVE synchronization: %s", strerror(errno));
goto error;
}
server.repl_transfer_read += nread;//更新读了的数目
/* Sync data on disk from time to time, otherwise at the end of the transfer
* we may suffer a big delay as the memory buffers are copied into the
* actual disk. */
if (server.repl_transfer_read >=
server.repl_transfer_last_fsync_off + REPL_MAX_WRITTEN_BEFORE_FSYNC)
{//隔段时间fsync一下，确保文件不断的刷磁盘了
off_t sync_size = server.repl_transfer_read - server.repl_transfer_last_fsync_off;
rdb_fsync_range(server.repl_transfer_fd, server.repl_transfer_last_fsync_off, sync_size);
server.repl_transfer_last_fsync_off += sync_size;
}
/* Check if the transfer is now complete */
if (server.repl_transfer_read == server.repl_transfer_size) {//看看是否文件全部接收完毕，如果完毕，GOOD
if (rename(server.repl_transfer_tmpfile,server.rdb_filename) == -1) {
redisLog(REDIS_WARNING,"Failed trying to rename the temp DB into dump.rdb in MASTER <-> SLAVE synchronization: %s", strerror(errno));
replicationAbortSyncTransfer();
return;
}
redisLog(REDIS_NOTICE, "MASTER <-> SLAVE sync: Loading DB in memory");
signalFlushedDb(-1);
emptyDb();//清空整个数据库
/* Before loading the DB into memory we need to delete the readable
* handler, otherwise it will get called recursively since
* rdbLoad() will call the event loop to process events from time to
* time for non blocking loading. */
aeDeleteFileEvent(server.el,server.repl_transfer_s,AE_READABLE);//上面注释说了，避免循环进入。
if (rdbLoad(server.rdb_filename) != REDIS_OK) {//开始加载RDB文件到内存数据结构中，这个要花费不少时间的。
redisLog(REDIS_WARNING,"Failed trying to load the MASTER synchronization DB from disk");
replicationAbortSyncTransfer();
return;
}
/* Final setup of the connected slave <- master link */
zfree(server.repl_transfer_tmpfile);
close(server.repl_transfer_fd);
server.master = createClient(server.repl_transfer_s);//重新注册可读事件毁掉为readQueryFromClient
server.master->flags |= REDIS_MASTER;
server.master->authenticated = 1;
server.repl_state = REDIS_REPL_CONNECTED;
//当切换server.repl_state 为 REDIS_REPL_CONNECTED的时候，新来的查询请求就能够被处理了，
//在processCommand里面就不会过滤非STALE请求，同时本slave也能接受下一级slave的SYNC指令了。
redisLog(REDIS_NOTICE, "MASTER <-> SLAVE sync: Finished with success");
/* Restart the AOF subsystem now that we finished the sync. This
* will trigger an AOF rewrite, and when done will start appending
* to the new file. */
if (server.aof_state != REDIS_AOF_OFF) {
int retry = 10;
stopAppendOnly();
while (retry-- && startAppendOnly() == REDIS_ERR) {
redisLog(REDIS_WARNING,"Failed enabling the AOF after successful master synchronization! Trying it again in one second.");
sleep(1);
}
if (!retry) {
redisLog(REDIS_WARNING,"FATAL: this slave instance finished the synchronization with its master, but the AOF can't be turned on. Exiting now.");
exit(1);
}
}
}
return;
error:
replicationAbortSyncTransfer();
return;
}