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Diskless replication: RDB -> slaves transfer draft implementation.

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This commit is contained in:
antirez
2014-10-14 10:11:26 +02:00
parent 850ea57c37
commit 75f0cd6520
5 changed files with 200 additions and 28 deletions
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81
src/replication.c
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@ -408,6 +408,28 @@ need_full_resync:
return REDIS_ERR;
}
/* Start a BGSAVE for replication goals, which is, selecting the disk or
* socket target depending on the configuration, and making sure that
* the script cache is flushed before to start.
*
* Returns REDIS_OK on success or REDIS_ERR otherwise. */
int startBgsaveForReplication(void) {
int retval;
redisLog(REDIS_NOTICE,"Starting BGSAVE for SYNC with target: %s",
server.repl_diskless ? "slaves sockets" : "disk");
if (server.repl_diskless)
retval = rdbSaveToSlavesSockets();
else
retval = rdbSaveBackground(server.rdb_filename);
/* Flush the script cache, since we need that slave differences are
* accumulated without requiring slaves to match our cached scripts. */
if (retval == REDIS_OK) replicationScriptCacheFlush();
return retval;
}
/* SYNC and PSYNC command implemenation. */
void syncCommand(redisClient *c) {
/* ignore SYNC if already slave or in monitor mode */
@ -465,7 +487,9 @@ void syncCommand(redisClient *c) {
/* Here we need to check if there is a background saving operation
* in progress, or if it is required to start one */
if (server.rdb_child_pid != -1) {
if (server.rdb_child_pid != -1 &&
server.rdb_child_type == REDIS_RDB_CHILD_TYPE_DISK)
{
/* Ok a background save is in progress. Let's check if it is a good
* one for replication, i.e. if there is another slave that is
* registering differences since the server forked to save. */
@ -480,12 +504,7 @@ void syncCommand(redisClient *c) {
}
if (ln) {
/* Perfect, the server is already registering differences for
* another slave. Set the right state, and copy the buffer.
*
* Note that if we found a slave in WAIT_BGSAVE_END state, this
* means that the current child is of type
* REDIS_RDB_CHILD_TYPE_DISK, since the first slave in this state
* can only be added when an RDB save with disk target is started. */
* another slave. Set the right state, and copy the buffer. */
copyClientOutputBuffer(c,slave);
c->replstate = REDIS_REPL_WAIT_BGSAVE_END;
redisLog(REDIS_NOTICE,"Waiting for end of BGSAVE for SYNC");
@ -495,17 +514,31 @@ void syncCommand(redisClient *c) {
c->replstate = REDIS_REPL_WAIT_BGSAVE_START;
redisLog(REDIS_NOTICE,"Waiting for next BGSAVE for SYNC");
}
} else if (server.rdb_child_pid != -1 &&
server.rdb_child_type == REDIS_RDB_CHILD_TYPE_SOCKET)
{
/* There is an RDB child process but it is writing directly to
* children sockets. We need to wait for the next BGSAVE
* in order to synchronize. */
c->replstate = REDIS_REPL_WAIT_BGSAVE_START;
redisLog(REDIS_NOTICE,"Waiting for next BGSAVE for SYNC");
} else {
/* Ok we don't have a BGSAVE in progress, let's start one. */
redisLog(REDIS_NOTICE,"Starting BGSAVE for SYNC");
if (rdbSaveBackground(server.rdb_filename) != REDIS_OK) {
redisLog(REDIS_NOTICE,"Replication failed, can't BGSAVE");
addReplyError(c,"Unable to perform background save");
return;
if (server.repl_diskless) {
/* Diskless replication RDB child is created inside
* replicationCron() since we want to delay its start a
* few seconds to wait for more slaves to arrive. */
c->replstate = REDIS_REPL_WAIT_BGSAVE_START;
redisLog(REDIS_NOTICE,"Delay next BGSAVE for SYNC");
} else {
/* Ok we don't have a BGSAVE in progress, let's start one. */
redisLog(REDIS_NOTICE,"Starting BGSAVE for SYNC");
if (startBgsaveForReplication() != REDIS_OK) {
redisLog(REDIS_NOTICE,"Replication failed, can't BGSAVE");
addReplyError(c,"Unable to perform background save");
return;
}
c->replstate = REDIS_REPL_WAIT_BGSAVE_END;
}
c->replstate = REDIS_REPL_WAIT_BGSAVE_END;
/* Flush the script cache for the new slave. */
replicationScriptCacheFlush();
}
if (server.repl_disable_tcp_nodelay)
@ -644,10 +677,15 @@ void sendBulkToSlave(aeEventLoop *el, int fd, void *privdata, int mask) {
/* This function is called at the end of every background saving.
* The argument bgsaveerr is REDIS_OK if the background saving succeeded
* otherwise REDIS_ERR is passed to the function.
* The 'type' argument is the type of the child that terminated
* (if it had a disk or socket target).
*
* The goal of this function is to handle slaves waiting for a successful
* background saving in order to perform non-blocking synchronization. */
void updateSlavesWaitingBgsave(int bgsaveerr) {
* background saving in order to perform non-blocking synchronization, and
* to schedule a new BGSAVE if there are slaves that attached while a
* BGSAVE was in progress, but it was not a good one for replication (no
* other slave was accumulating differences). */
void updateSlavesWaitingBgsave(int bgsaveerr, int type) {
listNode *ln;
int startbgsave = 0;
listIter li;
@ -687,12 +725,7 @@ void updateSlavesWaitingBgsave(int bgsaveerr) {
}
}
if (startbgsave) {
/* Since we are starting a new background save for one or more slaves,
* we flush the Replication Script Cache to use EVAL to propagate every
* new EVALSHA for the first time, since all the new slaves don't know
* about previous scripts. */
replicationScriptCacheFlush();
if (rdbSaveBackground(server.rdb_filename) != REDIS_OK) {
if (startBgsaveForReplication() != REDIS_OK) {
listIter li;
listRewind(server.slaves,&li);