CLIENT PAUSE and related API implemented.

The API is one of the bulding blocks of CLUSTER FAILOVER command that
executes a manual failover in Redis Cluster. However exposed as a
command that the user can call directly, it makes much simpler to
upgrade a standalone Redis instance using a slave in a safer way.

The commands works like that:

    CLIENT PAUSE <milliesconds>

All the clients that are not slaves and not in MONITOR state are paused
for the specified number of milliesconds. This means that slaves are
normally served in the meantime.

At the end of the specified amount of time all the clients are unblocked
and will continue operations normally. This command has no effects on
the population of the slow log, since clients are not blocked in the
middle of operations but only when there is to process new data.

Note that while the clients are unblocked, still new commands are
accepted and queued in the client buffer, so clients will likely not
block while writing to the server while the pause is active.
This commit is contained in:
antirez
2014-02-04 15:52:09 +01:00
parent b089ba98cc
commit 4919a13f50
3 changed files with 64 additions and 0 deletions

View File

@ -623,6 +623,8 @@ struct redisServer {
list *clients_to_close; /* Clients to close asynchronously */
list *slaves, *monitors; /* List of slaves and MONITORs */
redisClient *current_client; /* Current client, only used on crash report */
int clients_paused; /* True if clients are currently paused */
mstime_t clients_pause_end_time; /* Time when we undo clients_paused */
char neterr[ANET_ERR_LEN]; /* Error buffer for anet.c */
dict *migrate_cached_sockets;/* MIGRATE cached sockets */
/* RDB / AOF loading information */
@ -972,6 +974,8 @@ char *getClientLimitClassName(int class);
void flushSlavesOutputBuffers(void);
void disconnectSlaves(void);
int listenToPort(int port, int *fds, int *count);
void pauseClients(mstime_t duration);
int clientsArePaused(void);
#ifdef __GNUC__
void addReplyErrorFormat(redisClient *c, const char *fmt, ...)