-
antirez authored
Before this commit, after triggering a BGSAVE it was up to the caller of startBgsavForReplication() to handle slaves in WAIT_BGSAVE_START in order to update them accordingly. However when the replication target is the socket, this is not possible since the process of updating the slaves and sending the FULLRESYNC reply must be coupled with the process of starting an RDB save (the reason is, we need to send the FULLSYNC command and spawn a child that will start to send RDB data to the slaves ASAP). This commit moves the responsibility of handling slaves in WAIT_BGSAVE_START to startBgsavForReplication() so that for both diskless and disk-based replication we have the same chain of responsiblity. In order accomodate such change, the syncCommand() also needs to put the client in the slave list ASAP (just after the initial checks) and not at the end, so that startBgsavForReplication() can find the new slave alrady in the list. Another related change is what happens if the BGSAVE fails because of fork() or other errors: we now remove the slave from the list of slaves and send an error, scheduling the slave connection to be terminated. As a side effect of this change the following errors found by Oran Agra are fixed (thanks!): 1. rdbSaveToSlavesSockets() on failed fork will get the slaves cleaned up, otherwise they remain in a wrong state forever since we setup them for full resync before actually trying to fork. 2. updateSlavesWaitingBgsave() with replication target set as "socket" was broken since the function changed the slaves state from WAIT_BGSAVE_START to WAIT_BGSAVE_END via replicationSetupSlaveForFullResync(), so later rdbSaveToSlavesSockets() will not find any slave in the right state (WAIT_BGSAVE_START) to feed.
c2ff9de3