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CLUSTER RESET implemented.

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The new command is able to reset a cluster node so that it starts again
as a fresh node. By default the command performs a soft reset (the same
as calling it as CLUSTER RESET SOFT), and the following steps are
performed:

1) All slots are set as unassigned.
2) The list of known nodes is flushed.
3) Node is set as master if it is a slave.

When an hard reset is performed with CLUSTER RESET HARD the following
additional operations are performed:

4) A new Node ID is created at random.
5) Epochs are set to 0.

CLUSTER RESET is useful both when the sysadmin wants to reconfigure a
node with a different role (for example turning a slave into a master)
and for testing purposes.

It also may play a role in automatically provisioned Redis Clusters,
since it allows to reset a node back to the initial state in order to be
reconfigured.
This commit is contained in:
antirez 2014-05-15 11:43:06 +02:00
parent 8b9d5ecbd1
commit 796f4ae9f7
1 changed files with 88 additions and 0 deletions
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88
src/cluster.c
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@ -70,6 +70,8 @@ void clusterDoBeforeSleep(int flags);
void clusterSendUpdate(clusterLink *link, clusterNode *node);
void resetManualFailover(void);
void clusterCloseAllSlots(void);
void clusterSetNodeAsMaster(clusterNode *n);
void clusterDelNode(clusterNode *delnode);
/* -----------------------------------------------------------------------------
* Initialization
@ -462,6 +464,65 @@ void clusterInit(void) {
resetManualFailover();
}
/* Reset a node performing a soft or hard reset:
*
* 1) All other nodes are forget.
* 2) All the assigned / open slots are released.
* 3) If the node is a slave, it turns into a master.
* 5) Only for hard reset: a new Node ID is generated.
* 6) Only for hard reset: currentEpoch and configEpoch are set to 0.
* 7) The new configuration is saved and the cluster state updated. */
void clusterReset(int hard) {
dictIterator *di;
dictEntry *de;
int j;
/* Turn into master. */
if (nodeIsSlave(myself)) {
clusterSetNodeAsMaster(myself);
replicationUnsetMaster();
}
/* Close slots, reset manual failover state. */
clusterCloseAllSlots();
resetManualFailover();
/* Unassign all the slots. */
for (j = 0; j < REDIS_CLUSTER_SLOTS; j++) clusterDelSlot(j);
/* Forget all the nodes, but myself. */
di = dictGetSafeIterator(server.cluster->nodes);
while((de = dictNext(di)) != NULL) {
clusterNode *node = dictGetVal(de);
if (node == myself) continue;
clusterDelNode(node);
}
dictReleaseIterator(di);
/* Hard reset only: set epochs to 0, change node ID. */
if (hard) {
sds oldname;
server.cluster->currentEpoch = 0;
server.cluster->lastVoteEpoch = 0;
myself->configEpoch = 0;
/* To change the Node ID we need to remove the old name from the
* nodes table, change the ID, and re-add back with new name. */
oldname = sdsnewlen(myself->name, REDIS_CLUSTER_NAMELEN);
dictDelete(server.cluster->nodes,oldname);
sdsfree(oldname);
getRandomHexChars(myself->name, REDIS_CLUSTER_NAMELEN);
clusterAddNode(myself);
}
/* Make sure to persist the new config and update the state. */
clusterDoBeforeSleep(CLUSTER_TODO_SAVE_CONFIG|
CLUSTER_TODO_UPDATE_STATE|
CLUSTER_TODO_FSYNC_CONFIG);
}
/* -----------------------------------------------------------------------------
* CLUSTER communication link
* -------------------------------------------------------------------------- */
@ -3728,6 +3789,33 @@ void clusterCommand(redisClient *c) {
CLUSTER_TODO_SAVE_CONFIG);
addReply(c,shared.ok);
}
} else if (!strcasecmp(c->argv[1]->ptr,"reset") &&
(c->argc == 2 || c->argc == 3))
{
/* CLUSTER RESET [SOFT|HARD] */
int hard = 0;
/* Parse soft/hard argument. Default is soft. */
if (c->argc == 3) {
if (!strcasecmp(c->argv[2]->ptr,"hard")) {
hard = 1;
} else if (!strcasecmp(c->argv[2]->ptr,"hard")) {
hard = 0;
} else {
addReply(c,shared.syntaxerr);
return;
}
}
/* Slaves can be reset while containing data, but not master nodes
* that must be empty. */
if (nodeIsMaster(myself) && dictSize(c->db->dict) != 0) {
addReplyError(c,"CLUSTER RESET can't be called with "
"master nodes containing keys");
return;
}
clusterReset(hard);
addReply(c,shared.ok);
} else {
addReplyError(c,"Wrong CLUSTER subcommand or number of arguments");
}