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cluster import/export of hash slots implemented in the query redirection engine

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This commit is contained in:
antirez 2011-05-05 11:13:21 +02:00
parent a5dce40726
commit eda827f8b7
3 changed files with 59 additions and 22 deletions
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71
src/cluster.c
View File

@ -1605,12 +1605,19 @@ file_rd_err:
/* Return the pointer to the cluster node that is able to serve the query
* as all the keys belong to hash slots for which the node is in charge.
*
* If keys in query spawn multiple nodes NULL is returned. */
clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **argv, int argc, int *hashslot) {
* If the returned node should be used only for this request, the *ask
* integer is set to '1', otherwise to '0'. This is used in order to
* let the caller know if we should reply with -MOVED or with -ASK.
*
* If the request contains more than a single key NULL is returned,
* however a request with more then a key argument where the key is always
* the same is valid, like in: RPOPLPUSH mylist mylist.*/
clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **argv, int argc, int *hashslot, int *ask) {
clusterNode *n = NULL;
robj *firstkey = NULL;
multiState *ms, _ms;
multiCmd mc;
int i;
int i, slot = 0;
/* We handle all the cases as if they were EXEC commands, so we have
* a common code path for everything */
@ -1620,7 +1627,9 @@ clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **arg
if (!(c->flags & REDIS_MULTI)) return server.cluster.myself;
ms = &c->mstate;
} else {
/* Create a fake Multi State structure, with just one command */
/* In order to have a single codepath create a fake Multi State
* structure if the client is not in MULTI/EXEC state, this way
* we have a single codepath below. */
ms = &_ms;
_ms.commands = &mc;
_ms.count = 1;
@ -1629,6 +1638,8 @@ clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **arg
mc.cmd = cmd;
}
/* Check that all the keys are the same key, and get the slot and
* node for this key. */
for (i = 0; i < ms->count; i++) {
struct redisCommand *mcmd;
robj **margv;
@ -1641,24 +1652,48 @@ clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **arg
keyindex = getKeysFromCommand(mcmd,margv,margc,&numkeys,
REDIS_GETKEYS_PRELOAD);
for (j = 0; j < numkeys; j++) {
int slot = keyHashSlot((char*)margv[keyindex[j]]->ptr,
sdslen(margv[keyindex[j]]->ptr));
struct clusterNode *slotnode;
if (firstkey == NULL) {
/* This is the first key we see. Check what is the slot
* and node. */
firstkey = margv[keyindex[j]];
slotnode = server.cluster.slots[slot];
if (hashslot) *hashslot = slot;
/* Node not assigned? (Should never happen actually
* if we reached this function).
* Different node than the previous one?
* Return NULL, the cluster can't serve multi-node requests */
if (slotnode == NULL || (n && slotnode != n)) {
getKeysFreeResult(keyindex);
return NULL;
slot = keyHashSlot((char*)firstkey->ptr, sdslen(firstkey->ptr));
n = server.cluster.slots[slot];
redisAssert(n != NULL);
} else {
n = slotnode;
/* If it is not the first key, make sure it is exactly
* the same key as the first we saw. */
if (!equalStringObjects(firstkey,margv[keyindex[j]])) {
decrRefCount(firstkey);
getKeysFreeResult(keyindex);
return NULL;
}
}
}
getKeysFreeResult(keyindex);
}
return (n == NULL) ? server.cluster.myself : n;
if (ask) *ask = 0; /* This is the default. Set to 1 if needed later. */
/* No key at all in command? then we can serve the request
* without redirections. */
if (n == NULL) return server.cluster.myself;
if (hashslot) *hashslot = slot;
/* This request is about a slot we are migrating into another instance?
* Then we need to check if we have the key. If we have it we can reply.
* If instead is a new key, we pass the request to the node that is
* receiving the slot. */
if (n == server.cluster.myself &&
server.cluster.migrating_slots_to[slot] != NULL)
{
if (lookupKeyRead(&server.db[0],firstkey) == NULL) {
if (ask) *ask = 1;
return server.cluster.migrating_slots_to[slot];
}
}
/* Handle the case in which we are receiving this hash slot from
* another instance, so we'll accept the query even if in the table
* it is assigned to a different node. */
if (server.cluster.importing_slots_from[slot] != NULL)
return server.cluster.myself;
/* It's not a -ASK case. Base case: just return the right node. */
return n;
}

8
src/redis.c
View File

@ -1096,13 +1096,15 @@ int processCommand(redisClient *c) {
addReplyError(c,"The cluster is down. Check with CLUSTER INFO for more information");
return REDIS_OK;
} else {
clusterNode *n = getNodeByQuery(c,cmd,c->argv,c->argc,&hashslot);
int ask;
clusterNode *n = getNodeByQuery(c,cmd,c->argv,c->argc,&hashslot,&ask);
if (n == NULL) {
addReplyError(c,"Invalid cross-node request");
addReplyError(c,"Multi keys request invalid in cluster");
return REDIS_OK;
} else if (n != server.cluster.myself) {
addReplySds(c,sdscatprintf(sdsempty(),
"-MOVED %d %s:%d\r\n",hashslot,n->ip,n->port));
"-%s %d %s:%d\r\n", ask ? "ASK" : "MOVED",
hashslot,n->ip,n->port));
return REDIS_OK;
}
}

2
src/redis.h
View File

@ -1083,7 +1083,7 @@ unsigned int keyHashSlot(char *key, int keylen);
clusterNode *createClusterNode(char *nodename, int flags);
int clusterAddNode(clusterNode *node);
void clusterCron(void);
clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **argv, int argc, int *hashslot);
clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **argv, int argc, int *hashslot, int *ask);
/* Git SHA1 */
char *redisGitSHA1(void);