The implementation of the diskless replication was currently diskless only on the master side.
The slave side was still storing the received rdb file to the disk before loading it back in and parsing it.
This commit adds two modes to load rdb directly from socket:
1) when-empty
2) using "swapdb"
the third mode of using diskless slave by flushdb is risky and currently not included.
other changes:
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distinguish between aof configuration and state so that we can re-enable aof only when sync eventually
succeeds (and not when exiting from readSyncBulkPayload after a failed attempt)
also a CONFIG GET and INFO during rdb loading would have lied
When loading rdb from the network, don't kill the server on short read (that can be a network error)
Fix rdb check when performed on preamble AOF
tests:
run replication tests for diskless slave too
make replication test a bit more aggressive
Add test for diskless load swapdb
jemalloc 5 doesn't immediately release memory back to the OS, instead there's a decaying
mechanism, which doesn't work when there's no traffic (no allocations).
this is most evident if there's no traffic after flushdb, the RSS will remain high.
1) enable jemalloc background purging
2) explicitly purge in flushdb
In mostly production environment, normal user's behavior should be
limited.
Now in redis ACL mechanism we can do it like that:
user default on +@all ~* -@dangerous nopass
user admin on +@all ~* >someSeriousPassword
Then the default normal user can not execute dangerous commands like
FLUSHALL/KEYS.
But some admin commands are in dangerous category too like PSYNC,
and the configurations above will forbid replica from sync with master.
Finally I think we could add a new configuration for replication,
it is masteruser option, like this:
masteruser admin
masterauth someSeriousPassword
Then replica will try AUTH admin someSeriousPassword and get privilege
to execute PSYNC. If masteruser is NULL, replica would AUTH with only
masterauth like before.
Aliases added for all the commands mentioning slave. Moreover CONFIG
REWRITE will use the new names, and will be able to reuse the old lines
mentioning the old options.
This commit, in some parts derived from PR #3041 which is no longer
possible to merge (because the user deleted the original branch),
implements the ability of slaves to have a special configuration
preventing that they try to start a failover when the master is failing.
There are multiple reasons for wanting this, and the feautre was
requested in issue #3021 time ago.
The differences between this patch and the original PR are the
following:
1. The flag is saved/loaded on the nodes configuration.
2. The 'myself' node is now flag-aware, the flag is updated as needed
when the configuration is changed via CONFIG SET.
3. The flag name uses NOFAILOVER instead of NO_FAILOVER to be consistent
with existing NOADDR.
4. The redis.conf documentation was rewritten.
Thanks to @deep011 for the original patch.
