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| author | antirez <antirez@gmail.com> | 2012-08-31 15:32:57 +0200 |
|---|---|---|
| committer | antirez <antirez@gmail.com> | 2012-09-02 12:24:38 +0200 |
| commit | bb66fc312036e444a950df27dd7cb2e3db6b4b05 (patch) | |
| tree | dfaa174440b199abf08c054eb103cfa887a25b6b /src/redis.h | |
| parent | e323635c2d9d9039442cd1014932e4dd314d2d06 (diff) | |
| download | redis-bb66fc312036e444a950df27dd7cb2e3db6b4b05.tar.gz | |
Send an async PING before starting replication with master.
During the first synchronization step of the replication process, a Redis
slave connects with the master in a non blocking way. However once the
connection is established the replication continues sending the REPLCONF
command, and sometimes the AUTH command if needed. Those commands are
send in a partially blocking way (blocking with timeout in the order of
seconds).
Because it is common for a blocked master to accept connections even if
it is actually not able to reply to the slave requests, it was easy for
a slave to block if the master had serious issues, but was still able to
accept connections in the listening socket.
For this reason we now send an asynchronous PING request just after the
non blocking connection ended in a successful way, and wait for the
reply before to continue with the replication process. It is very
unlikely that a master replying to PING can't reply to the other
commands.
This solution was proposed by Didier Spezia (Thanks!) so that we don't
need to turn all the replication process into a non blocking affair, but
still the probability of a slave blocked is minimal even in the event of
a failing master.
Also we now use getsockopt(SO_ERROR) in order to check errors ASAP
in the event handler, instead of waiting for actual I/O to return an
error.
This commit fixes issue #632.
Diffstat (limited to 'src/redis.h')
| -rw-r--r-- | src/redis.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/redis.h b/src/redis.h index 2641aeae9..34afd0f88 100644 --- a/src/redis.h +++ b/src/redis.h @@ -167,8 +167,9 @@ #define REDIS_REPL_NONE 0 /* No active replication */ #define REDIS_REPL_CONNECT 1 /* Must connect to master */ #define REDIS_REPL_CONNECTING 2 /* Connecting to master */ -#define REDIS_REPL_TRANSFER 3 /* Receiving .rdb from master */ -#define REDIS_REPL_CONNECTED 4 /* Connected to master */ +#define REDIS_REPL_RECEIVE_PONG 3 /* Wait for PING reply */ +#define REDIS_REPL_TRANSFER 4 /* Receiving .rdb from master */ +#define REDIS_REPL_CONNECTED 5 /* Connected to master */ /* Synchronous read timeout - slave side */ #define REDIS_REPL_SYNCIO_TIMEOUT 5 |