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Fix for issue 516, rewriting the command vector to correctly repliate BRPOPLPUSH. Still to test everything, especially edge cases

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This commit is contained in:
antirez 2011-05-26 13:49:03 +02:00
parent afc151d3ba
commit 3769dbd722
1 changed files with 56 additions and 7 deletions
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63
src/t_list.c
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@ -624,6 +624,31 @@ void lremCommand(redisClient *c) {
if (removed) touchWatchedKey(c->db,c->argv[1]);
}
void rewriteClientCommandVector(redisClient *c, int argc, ...) {
va_list ap;
int j;
robj **argv; /* The new argument vector */
argv = zmalloc(sizeof(robj*)*argc);
va_start(ap,argc);
for (j = 0; j < argc; j++) {
robj *a;
a = va_arg(ap, robj*);
argv[j] = a;
incrRefCount(a);
}
/* We free the objects in the original vector at the end, so we are
* sure that if the same objects are reused in the new vector the
* refcount gets incremented before it gets decremented. */
for (j = 0; j < c->argc; j++) decrRefCount(c->argv[j]);
zfree(c->argv);
/* Replace argv and argc with our new versions. */
c->argv = argv;
c->argc = argc;
va_end(ap);
}
/* This is the semantic of this command:
* RPOPLPUSH srclist dstlist:
* IF LLEN(srclist) > 0
@ -640,7 +665,9 @@ void lremCommand(redisClient *c) {
* as well. This command was originally proposed by Ezra Zygmuntowicz.
*/
void rpoplpushHandlePush(redisClient *c, robj *dstkey, robj *dstobj, robj *value) {
void rpoplpushHandlePush(redisClient *origclient, redisClient *c, robj *dstkey, robj *dstobj, robj *value) {
robj *aux;
if (!handleClientsWaitingListPush(c,dstkey,value)) {
/* Create the list if the key does not exist */
if (!dstobj) {
@ -648,9 +675,25 @@ void rpoplpushHandlePush(redisClient *c, robj *dstkey, robj *dstobj, robj *value
dbAdd(c->db,dstkey,dstobj);
} else {
touchWatchedKey(c->db,dstkey);
server.dirty++;
}
listTypePush(dstobj,value,REDIS_HEAD);
/* If we are pushing as a result of LPUSH against a key
* watched by BLPOPLPUSH, we need to rewrite the command vector.
* But if this is called directly by RPOPLPUSH (either directly
* or via a BRPOPLPUSH where the popped list exists)
* we should replicate the BRPOPLPUSH command itself. */
if (c != origclient) {
aux = createStringObject("LPUSH",5);
rewriteClientCommandVector(origclient,3,aux,dstkey,value);
decrRefCount(aux);
} else {
/* Make sure to always use RPOPLPUSH in the replication / AOF,
* even if the original command was BRPOPLPUSH. */
aux = createStringObject("RPOPLPUSH",9);
rewriteClientCommandVector(origclient,3,aux,c->argv[1],c->argv[2]);
decrRefCount(aux);
}
server.dirty++;
}
/* Always send the pushed value to the client. */
@ -666,16 +709,22 @@ void rpoplpushCommand(redisClient *c) {
addReply(c,shared.nullbulk);
} else {
robj *dobj = lookupKeyWrite(c->db,c->argv[2]);
robj *touchedkey = c->argv[1];
if (dobj && checkType(c,dobj,REDIS_LIST)) return;
value = listTypePop(sobj,REDIS_TAIL);
rpoplpushHandlePush(c,c->argv[2],dobj,value);
/* We saved touched key, and protect it, since rpoplpushHandlePush
* may change the client command argument vector. */
incrRefCount(touchedkey);
rpoplpushHandlePush(c,c,c->argv[2],dobj,value);
/* listTypePop returns an object with its refcount incremented */
decrRefCount(value);
/* Delete the source list when it is empty */
if (listTypeLength(sobj) == 0) dbDelete(c->db,c->argv[1]);
touchWatchedKey(c->db,c->argv[1]);
if (listTypeLength(sobj) == 0) dbDelete(c->db,touchedkey);
touchWatchedKey(c->db,touchedkey);
decrRefCount(touchedkey);
server.dirty++;
}
}
@ -828,14 +877,14 @@ int handleClientsWaitingListPush(redisClient *c, robj *key, robj *ele) {
addReplyMultiBulkLen(receiver,2);
addReplyBulk(receiver,key);
addReplyBulk(receiver,ele);
return 1;
return 1; /* Serve just the first client as in B[RL]POP semantics */
} else {
/* BRPOPLPUSH, note that receiver->db is always equal to c->db. */
dstobj = lookupKeyWrite(receiver->db,dstkey);
if (dstobj && checkType(receiver,dstobj,REDIS_LIST)) {
decrRefCount(dstkey);
} else {
rpoplpushHandlePush(receiver,dstkey,dstobj,ele);
rpoplpushHandlePush(c,receiver,dstkey,dstobj,ele);
decrRefCount(dstkey);
return 1;
}