X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/7c25a43adc67c4a8d08e930aa92f1c5575ec3646..524b79d231551845a865aea9558188f7108cc352:/src/t_list.c

diff --git a/src/t_list.c b/src/t_list.c
index d14de708..77e40eb6 100644
--- a/src/t_list.c
+++ b/src/t_list.c
@@ -1,5 +1,7 @@
 #include "redis.h"
 
+void signalListAsReady(redisClient *c, robj *key);
+
 /*-----------------------------------------------------------------------------
  * List API
  *----------------------------------------------------------------------------*/
@@ -14,6 +16,11 @@ void listTypeTryConversion(robj *subject, robj *value) {
             listTypeConvert(subject,REDIS_ENCODING_LINKEDLIST);
 }
 
+/* The function pushes an elmenet to the specified list object 'subject',
+ * at head or tail position as specified by 'where'.
+ *
+ * There is no need for the caller to incremnet the refcount of 'value' as
+ * the function takes care of it if needed. */
 void listTypePush(robj *subject, robj *value, int where) {
     /* Check if we need to convert the ziplist */
     listTypeTryConversion(subject,value);
@@ -86,7 +93,7 @@ unsigned long listTypeLength(robj *subject) {
 }
 
 /* Initialize an iterator at the specified index. */
-listTypeIterator *listTypeInitIterator(robj *subject, int index, unsigned char direction) {
+listTypeIterator *listTypeInitIterator(robj *subject, long index, unsigned char direction) {
     listTypeIterator *li = zmalloc(sizeof(listTypeIterator));
     li->subject = subject;
     li->encoding = subject->encoding;
@@ -198,7 +205,7 @@ void listTypeInsert(listTypeEntry *entry, robj *value, int where) {
 int listTypeEqual(listTypeEntry *entry, robj *o) {
     listTypeIterator *li = entry->li;
     if (li->encoding == REDIS_ENCODING_ZIPLIST) {
-        redisAssert(o->encoding == REDIS_ENCODING_RAW);
+        redisAssertWithInfo(NULL,o,o->encoding == REDIS_ENCODING_RAW);
         return ziplistCompare(entry->zi,o->ptr,sdslen(o->ptr));
     } else if (li->encoding == REDIS_ENCODING_LINKEDLIST) {
         return equalStringObjects(o,listNodeValue(entry->ln));
@@ -235,7 +242,7 @@ void listTypeDelete(listTypeEntry *entry) {
 void listTypeConvert(robj *subject, int enc) {
     listTypeIterator *li;
     listTypeEntry entry;
-    redisAssert(subject->type == REDIS_LIST);
+    redisAssertWithInfo(NULL,subject,subject->type == REDIS_LIST);
 
     if (enc == REDIS_ENCODING_LINKEDLIST) {
         list *l = listCreate();
@@ -259,30 +266,29 @@ void listTypeConvert(robj *subject, int enc) {
  *----------------------------------------------------------------------------*/
 
 void pushGenericCommand(redisClient *c, int where) {
+    int j, waiting = 0, pushed = 0;
     robj *lobj = lookupKeyWrite(c->db,c->argv[1]);
-    c->argv[2] = tryObjectEncoding(c->argv[2]);
-    if (lobj == NULL) {
-        if (handleClientsWaitingListPush(c,c->argv[1],c->argv[2])) {
-            addReply(c,shared.cone);
-            return;
-        }
-        lobj = createZiplistObject();
-        dbAdd(c->db,c->argv[1],lobj);
-    } else {
-        if (lobj->type != REDIS_LIST) {
-            addReply(c,shared.wrongtypeerr);
-            return;
-        }
-        if (handleClientsWaitingListPush(c,c->argv[1],c->argv[2])) {
-            touchWatchedKey(c->db,c->argv[1]);
-            addReply(c,shared.cone);
-            return;
+    int may_have_waiting_clients = (lobj == NULL);
+
+    if (lobj && lobj->type != REDIS_LIST) {
+        addReply(c,shared.wrongtypeerr);
+        return;
+    }
+
+    if (may_have_waiting_clients) signalListAsReady(c,c->argv[1]);
+
+    for (j = 2; j < c->argc; j++) {
+        c->argv[j] = tryObjectEncoding(c->argv[j]);
+        if (!lobj) {
+            lobj = createZiplistObject();
+            dbAdd(c->db,c->argv[1],lobj);
         }
+        listTypePush(lobj,c->argv[j],where);
+        pushed++;
     }
-    listTypePush(lobj,c->argv[2],where);
-    addReplyLongLong(c,listTypeLength(lobj));
-    touchWatchedKey(c->db,c->argv[1]);
-    server.dirty++;
+    addReplyLongLong(c, waiting + (lobj ? listTypeLength(lobj) : 0));
+    if (pushed) signalModifiedKey(c->db,c->argv[1]);
+    server.dirty += pushed;
 }
 
 void lpushCommand(redisClient *c) {
@@ -305,7 +311,7 @@ void pushxGenericCommand(redisClient *c, robj *refval, robj *val, int where) {
     if (refval != NULL) {
         /* Note: we expect refval to be string-encoded because it is *not* the
          * last argument of the multi-bulk LINSERT. */
-        redisAssert(refval->encoding == REDIS_ENCODING_RAW);
+        redisAssertWithInfo(c,refval,refval->encoding == REDIS_ENCODING_RAW);
 
         /* We're not sure if this value can be inserted yet, but we cannot
          * convert the list inside the iterator. We don't want to loop over
@@ -330,7 +336,7 @@ void pushxGenericCommand(redisClient *c, robj *refval, robj *val, int where) {
             if (subject->encoding == REDIS_ENCODING_ZIPLIST &&
                 ziplistLen(subject->ptr) > server.list_max_ziplist_entries)
                     listTypeConvert(subject,REDIS_ENCODING_LINKEDLIST);
-            touchWatchedKey(c->db,c->argv[1]);
+            signalModifiedKey(c->db,c->argv[1]);
             server.dirty++;
         } else {
             /* Notify client of a failed insert */
@@ -339,7 +345,7 @@ void pushxGenericCommand(redisClient *c, robj *refval, robj *val, int where) {
         }
     } else {
         listTypePush(subject,val,where);
-        touchWatchedKey(c->db,c->argv[1]);
+        signalModifiedKey(c->db,c->argv[1]);
         server.dirty++;
     }
 
@@ -376,9 +382,12 @@ void llenCommand(redisClient *c) {
 void lindexCommand(redisClient *c) {
     robj *o = lookupKeyReadOrReply(c,c->argv[1],shared.nullbulk);
     if (o == NULL || checkType(c,o,REDIS_LIST)) return;
-    int index = atoi(c->argv[2]->ptr);
+    long index;
     robj *value = NULL;
 
+    if ((getLongFromObjectOrReply(c, c->argv[2], &index, NULL) != REDIS_OK))
+        return;
+
     if (o->encoding == REDIS_ENCODING_ZIPLIST) {
         unsigned char *p;
         unsigned char *vstr;
@@ -412,9 +421,12 @@ void lindexCommand(redisClient *c) {
 void lsetCommand(redisClient *c) {
     robj *o = lookupKeyWriteOrReply(c,c->argv[1],shared.nokeyerr);
     if (o == NULL || checkType(c,o,REDIS_LIST)) return;
-    int index = atoi(c->argv[2]->ptr);
+    long index;
     robj *value = (c->argv[3] = tryObjectEncoding(c->argv[3]));
 
+    if ((getLongFromObjectOrReply(c, c->argv[2], &index, NULL) != REDIS_OK))
+        return;
+
     listTypeTryConversion(o,value);
     if (o->encoding == REDIS_ENCODING_ZIPLIST) {
         unsigned char *p, *zl = o->ptr;
@@ -427,7 +439,7 @@ void lsetCommand(redisClient *c) {
             o->ptr = ziplistInsert(o->ptr,p,value->ptr,sdslen(value->ptr));
             decrRefCount(value);
             addReply(c,shared.ok);
-            touchWatchedKey(c->db,c->argv[1]);
+            signalModifiedKey(c->db,c->argv[1]);
             server.dirty++;
         }
     } else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
@@ -439,7 +451,7 @@ void lsetCommand(redisClient *c) {
             listNodeValue(ln) = value;
             incrRefCount(value);
             addReply(c,shared.ok);
-            touchWatchedKey(c->db,c->argv[1]);
+            signalModifiedKey(c->db,c->argv[1]);
             server.dirty++;
         }
     } else {
@@ -458,7 +470,7 @@ void popGenericCommand(redisClient *c, int where) {
         addReplyBulk(c,value);
         decrRefCount(value);
         if (listTypeLength(o) == 0) dbDelete(c->db,c->argv[1]);
-        touchWatchedKey(c->db,c->argv[1]);
+        signalModifiedKey(c->db,c->argv[1]);
         server.dirty++;
     }
 }
@@ -472,12 +484,11 @@ void rpopCommand(redisClient *c) {
 }
 
 void lrangeCommand(redisClient *c) {
-    robj *o, *value;
-    int start = atoi(c->argv[2]->ptr);
-    int end = atoi(c->argv[3]->ptr);
-    int llen;
-    int rangelen, j;
-    listTypeEntry entry;
+    robj *o;
+    long start, end, llen, rangelen;
+
+    if ((getLongFromObjectOrReply(c, c->argv[2], &start, NULL) != REDIS_OK) ||
+        (getLongFromObjectOrReply(c, c->argv[3], &end, NULL) != REDIS_OK)) return;
 
     if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.emptymultibulk)) == NULL
          || checkType(c,o,REDIS_LIST)) return;
@@ -499,25 +510,47 @@ void lrangeCommand(redisClient *c) {
 
     /* Return the result in form of a multi-bulk reply */
     addReplyMultiBulkLen(c,rangelen);
-    listTypeIterator *li = listTypeInitIterator(o,start,REDIS_TAIL);
-    for (j = 0; j < rangelen; j++) {
-        redisAssert(listTypeNext(li,&entry));
-        value = listTypeGet(&entry);
-        addReplyBulk(c,value);
-        decrRefCount(value);
+    if (o->encoding == REDIS_ENCODING_ZIPLIST) {
+        unsigned char *p = ziplistIndex(o->ptr,start);
+        unsigned char *vstr;
+        unsigned int vlen;
+        long long vlong;
+
+        while(rangelen--) {
+            ziplistGet(p,&vstr,&vlen,&vlong);
+            if (vstr) {
+                addReplyBulkCBuffer(c,vstr,vlen);
+            } else {
+                addReplyBulkLongLong(c,vlong);
+            }
+            p = ziplistNext(o->ptr,p);
+        }
+    } else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
+        listNode *ln;
+
+        /* If we are nearest to the end of the list, reach the element
+         * starting from tail and going backward, as it is faster. */
+        if (start > llen/2) start -= llen;
+        ln = listIndex(o->ptr,start);
+
+        while(rangelen--) {
+            addReplyBulk(c,ln->value);
+            ln = ln->next;
+        }
+    } else {
+        redisPanic("List encoding is not LINKEDLIST nor ZIPLIST!");
     }
-    listTypeReleaseIterator(li);
 }
 
 void ltrimCommand(redisClient *c) {
     robj *o;
-    int start = atoi(c->argv[2]->ptr);
-    int end = atoi(c->argv[3]->ptr);
-    int llen;
-    int j, ltrim, rtrim;
+    long start, end, llen, j, ltrim, rtrim;
     list *list;
     listNode *ln;
 
+    if ((getLongFromObjectOrReply(c, c->argv[2], &start, NULL) != REDIS_OK) ||
+        (getLongFromObjectOrReply(c, c->argv[3], &end, NULL) != REDIS_OK)) return;
+
     if ((o = lookupKeyWriteOrReply(c,c->argv[1],shared.ok)) == NULL ||
         checkType(c,o,REDIS_LIST)) return;
     llen = listTypeLength(o);
@@ -557,7 +590,7 @@ void ltrimCommand(redisClient *c) {
         redisPanic("Unknown list encoding");
     }
     if (listTypeLength(o) == 0) dbDelete(c->db,c->argv[1]);
-    touchWatchedKey(c->db,c->argv[1]);
+    signalModifiedKey(c->db,c->argv[1]);
     server.dirty++;
     addReply(c,shared.ok);
 }
@@ -565,10 +598,13 @@ void ltrimCommand(redisClient *c) {
 void lremCommand(redisClient *c) {
     robj *subject, *obj;
     obj = c->argv[3] = tryObjectEncoding(c->argv[3]);
-    int toremove = atoi(c->argv[2]->ptr);
-    int removed = 0;
+    long toremove;
+    long removed = 0;
     listTypeEntry entry;
 
+    if ((getLongFromObjectOrReply(c, c->argv[2], &toremove, NULL) != REDIS_OK))
+        return;
+
     subject = lookupKeyWriteOrReply(c,c->argv[1],shared.czero);
     if (subject == NULL || checkType(c,subject,REDIS_LIST)) return;
 
@@ -600,56 +636,66 @@ void lremCommand(redisClient *c) {
 
     if (listTypeLength(subject) == 0) dbDelete(c->db,c->argv[1]);
     addReplyLongLong(c,removed);
-    if (removed) touchWatchedKey(c->db,c->argv[1]);
+    if (removed) signalModifiedKey(c->db,c->argv[1]);
 }
 
 /* This is the semantic of this command:
  *  RPOPLPUSH srclist dstlist:
- *   IF LLEN(srclist) > 0
- *     element = RPOP srclist
- *     LPUSH dstlist element
- *     RETURN element
- *   ELSE
- *     RETURN nil
- *   END
+ *    IF LLEN(srclist) > 0
+ *      element = RPOP srclist
+ *      LPUSH dstlist element
+ *      RETURN element
+ *    ELSE
+ *      RETURN nil
+ *    END
  *  END
  *
  * The idea is to be able to get an element from a list in a reliable way
  * since the element is not just returned but pushed against another list
  * as well. This command was originally proposed by Ezra Zygmuntowicz.
  */
+
+void rpoplpushHandlePush(redisClient *c, robj *dstkey, robj *dstobj, robj *value) {
+    /* Create the list if the key does not exist */
+    if (!dstobj) {
+        dstobj = createZiplistObject();
+        dbAdd(c->db,dstkey,dstobj);
+        signalListAsReady(c,dstkey);
+    }
+    signalModifiedKey(c->db,dstkey);
+    listTypePush(dstobj,value,REDIS_HEAD);
+    /* Always send the pushed value to the client. */
+    addReplyBulk(c,value);
+}
+
 void rpoplpushCommand(redisClient *c) {
     robj *sobj, *value;
     if ((sobj = lookupKeyWriteOrReply(c,c->argv[1],shared.nullbulk)) == NULL ||
         checkType(c,sobj,REDIS_LIST)) return;
 
     if (listTypeLength(sobj) == 0) {
+        /* This may only happen after loading very old RDB files. Recent
+         * versions of Redis delete keys of empty lists. */
         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);
-
-        /* Add the element to the target list (unless it's directly
-         * passed to some BLPOP-ing client */
-        if (!handleClientsWaitingListPush(c,c->argv[2],value)) {
-            /* Create the list if the key does not exist */
-            if (!dobj) {
-                dobj = createZiplistObject();
-                dbAdd(c->db,c->argv[2],dobj);
-            }
-            listTypePush(dobj,value,REDIS_HEAD);
-        }
-
-        /* Send the element to the client as reply as well */
-        addReplyBulk(c,value);
+        /* We saved touched key, and protect it, since rpoplpushHandlePush
+         * may change the client command argument vector (it does not
+         * currently). */
+        incrRefCount(touchedkey);
+        rpoplpushHandlePush(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);
+        signalModifiedKey(c->db,touchedkey);
+        decrRefCount(touchedkey);
         server.dirty++;
     }
 }
@@ -658,20 +704,10 @@ void rpoplpushCommand(redisClient *c) {
  * Blocking POP operations
  *----------------------------------------------------------------------------*/
 
-/* Currently Redis blocking operations support is limited to list POP ops,
- * so the current implementation is not fully generic, but it is also not
- * completely specific so it will not require a rewrite to support new
- * kind of blocking operations in the future.
- *
- * Still it's important to note that list blocking operations can be already
- * used as a notification mechanism in order to implement other blocking
- * operations at application level, so there must be a very strong evidence
- * of usefulness and generality before new blocking operations are implemented.
- *
- * This is how the current blocking POP works, we use BLPOP as example:
+/* This is how the current blocking POP works, we use BLPOP as example:
  * - If the user calls BLPOP and the key exists and contains a non empty list
  *   then LPOP is called instead. So BLPOP is semantically the same as LPOP
- *   if there is not to block.
+ *   if blocking is not required.
  * - If instead BLPOP is called and the key does not exists or the list is
  *   empty we need to block. In order to do so we remove the notification for
  *   new data to read in the client socket (so that we'll not serve new
@@ -679,12 +715,10 @@ void rpoplpushCommand(redisClient *c) {
  *   in a dictionary (db->blocking_keys) mapping keys to a list of clients
  *   blocking for this keys.
  * - If a PUSH operation against a key with blocked clients waiting is
- *   performed, we serve the first in the list: basically instead to push
- *   the new element inside the list we return it to the (first / oldest)
- *   blocking client, unblock the client, and remove it form the list.
- *
- * The above comment and the source code should be enough in order to understand
- * the implementation and modify / fix it later.
+ *   performed, we mark this key as "ready", and after the current command,
+ *   MULTI/EXEC block, or script, is executed, we serve all the clients waiting
+ *   for this list, from the one that blocked first, to the last, accordingly
+ *   to the number of elements we have in the ready list.
  */
 
 /* Set a client in blocking mode for the specified key, with the specified
@@ -694,18 +728,18 @@ void blockForKeys(redisClient *c, robj **keys, int numkeys, time_t timeout, robj
     list *l;
     int j;
 
-    c->bstate.keys = zmalloc(sizeof(robj*)*numkeys);
-    c->bstate.count = numkeys;
-    c->bstate.timeout = timeout;
-    c->bstate.target = target;
+    c->bpop.keys = zmalloc(sizeof(robj*)*numkeys);
+    c->bpop.count = numkeys;
+    c->bpop.timeout = timeout;
+    c->bpop.target = target;
 
     if (target != NULL) {
-      incrRefCount(target);
+        incrRefCount(target);
     }
 
     for (j = 0; j < numkeys; j++) {
         /* Add the key in the client structure, to map clients -> keys */
-        c->bstate.keys[j] = keys[j];
+        c->bpop.keys[j] = keys[j];
         incrRefCount(keys[j]);
 
         /* And in the other "side", to map keys -> clients */
@@ -717,15 +751,15 @@ void blockForKeys(redisClient *c, robj **keys, int numkeys, time_t timeout, robj
             l = listCreate();
             retval = dictAdd(c->db->blocking_keys,keys[j],l);
             incrRefCount(keys[j]);
-            redisAssert(retval == DICT_OK);
+            redisAssertWithInfo(c,keys[j],retval == DICT_OK);
         } else {
-            l = dictGetEntryVal(de);
+            l = dictGetVal(de);
         }
         listAddNodeTail(l,c);
     }
     /* Mark the client as a blocked client */
     c->flags |= REDIS_BLOCKED;
-    server.blpop_blocked_clients++;
+    server.bpop_blocked_clients++;
 }
 
 /* Unblock a client that's waiting in a blocking operation such as BLPOP */
@@ -734,88 +768,235 @@ void unblockClientWaitingData(redisClient *c) {
     list *l;
     int j;
 
-    redisAssert(c->bstate.keys != NULL);
+    redisAssertWithInfo(c,NULL,c->bpop.keys != NULL);
     /* The client may wait for multiple keys, so unblock it for every key. */
-    for (j = 0; j < c->bstate.count; j++) {
+    for (j = 0; j < c->bpop.count; j++) {
         /* Remove this client from the list of clients waiting for this key. */
-        de = dictFind(c->db->blocking_keys,c->bstate.keys[j]);
-        redisAssert(de != NULL);
-        l = dictGetEntryVal(de);
+        de = dictFind(c->db->blocking_keys,c->bpop.keys[j]);
+        redisAssertWithInfo(c,c->bpop.keys[j],de != NULL);
+        l = dictGetVal(de);
         listDelNode(l,listSearchKey(l,c));
         /* If the list is empty we need to remove it to avoid wasting memory */
         if (listLength(l) == 0)
-            dictDelete(c->db->blocking_keys,c->bstate.keys[j]);
-        decrRefCount(c->bstate.keys[j]);
-    }
-
-    if (c->bstate.target != NULL) {
-        decrRefCount(c->bstate.target);
+            dictDelete(c->db->blocking_keys,c->bpop.keys[j]);
+        decrRefCount(c->bpop.keys[j]);
     }
 
     /* Cleanup the client structure */
-    zfree(c->bstate.keys);
-    c->bstate.keys = NULL;
-    c->bstate.target = NULL;
-    c->flags &= (~REDIS_BLOCKED);
-    server.blpop_blocked_clients--;
-    /* We want to process data if there is some command waiting
-     * in the input buffer. Note that this is safe even if
-     * unblockClientWaitingData() gets called from freeClient() because
-     * freeClient() will be smart enough to call this function
-     * *after* c->querybuf was set to NULL. */
-    if (c->querybuf && sdslen(c->querybuf) > 0) processInputBuffer(c);
-}
-
-/* This should be called from any function PUSHing into lists.
- * 'c' is the "pushing client", 'key' is the key it is pushing data against,
- * 'ele' is the element pushed.
- *
- * If the function returns 0 there was no client waiting for a list push
- * against this key.
- *
- * If the function returns 1 there was a client waiting for a list push
- * against this key, the element was passed to this client thus it's not
- * needed to actually add it to the list and the caller should return asap. */
-int handleClientsWaitingListPush(redisClient *c, robj *key, robj *ele) {
-    struct dictEntry *de;
-    redisClient *receiver;
-    list *l;
-    listNode *ln;
+    zfree(c->bpop.keys);
+    c->bpop.keys = NULL;
+    if (c->bpop.target) decrRefCount(c->bpop.target);
+    c->bpop.target = NULL;
+    c->flags &= ~REDIS_BLOCKED;
+    c->flags |= REDIS_UNBLOCKED;
+    server.bpop_blocked_clients--;
+    listAddNodeTail(server.unblocked_clients,c);
+}
 
-    de = dictFind(c->db->blocking_keys,key);
-    if (de == NULL) return 0;
-    l = dictGetEntryVal(de);
-    ln = listFirst(l);
-    redisAssert(ln != NULL);
-    receiver = ln->value;
+/* If the specified key has clients blocked waiting for list pushes, this
+ * function will put the key reference into the server.ready_keys list.
+ * Note that db->ready_keys is an hash table that allows us to avoid putting
+ * the same key agains and again in the list in case of multiple pushes
+ * made by a script or in the context of MULTI/EXEC.
+ *
+ * The list will be finally processed by handleClientsBlockedOnLists() */
+void signalListAsReady(redisClient *c, robj *key) {
+    readyList *rl;
+
+    /* No clients blocking for this key? No need to queue it. */
+    if (dictFind(c->db->blocking_keys,key) == NULL) return;
+
+    /* Key was already signaled? No need to queue it again. */
+    if (dictFind(c->db->ready_keys,key) != NULL) return;
+
+    /* Ok, we need to queue this key into server.ready_keys. */
+    rl = zmalloc(sizeof(*rl));
+    rl->key = key;
+    rl->db = c->db;
+    incrRefCount(key);
+    listAddNodeTail(server.ready_keys,rl);
+
+    /* We also add the key in the db->ready_keys dictionary in order
+     * to avoid adding it multiple times into a list with a simple O(1)
+     * check. */
+    incrRefCount(key);
+    redisAssert(dictAdd(c->db->ready_keys,key,NULL) == DICT_OK);
+}
 
-    if (receiver->bstate.target == NULL) {
-        /* BRPOP/BLPOP return a multi-bulk with the name
-         * of the popped list */
+/* This is an helper function for handleClientsBlockedOnLists(). It's work
+ * is to serve a specific client (receiver) that is blocked on 'key'
+ * in the context of the specified 'db', doing the following:
+ *
+ * 1) Provide the client with the 'value' element.
+ * 2) If the dstkey is not NULL (we are serving a BRPOPLPUSH) also push the
+ *    'value' element on the destionation list (the LPUSH side of the command).
+ * 3) Propagate the resulting BRPOP, BLPOP and additional LPUSH if any into
+ *    the AOF and replication channel.
+ *
+ * The argument 'where' is REDIS_TAIL or REDIS_HEAD, and indicates if the
+ * 'value' element was popped fron the head (BLPOP) or tail (BRPOP) so that
+ * we can propagate the command properly.
+ *
+ * The function returns REDIS_OK if we are able to serve the client, otherwise
+ * REDIS_ERR is returned to signal the caller that the list POP operation
+ * should be undoed as the client was not served: This only happens for
+ * BRPOPLPUSH that fails to push the value to the destination key as it is
+ * of the wrong type. */
+int serveClientBlockedOnList(redisClient *receiver, robj *key, robj *dstkey, redisDb *db, robj *value, int where)
+{
+    robj *argv[3];
+
+    if (dstkey == NULL) {
+        /* Propagate the [LR]POP operation. */
+        argv[0] = (where == REDIS_HEAD) ? shared.lpop :
+                                          shared.rpop;
+        argv[1] = key;
+        propagate((where == REDIS_HEAD) ?
+            server.lpopCommand : server.rpopCommand,
+            db->id,argv,2,REDIS_PROPAGATE_AOF|REDIS_PROPAGATE_REPL);
+
+        /* BRPOP/BLPOP */
         addReplyMultiBulkLen(receiver,2);
         addReplyBulk(receiver,key);
-        addReplyBulk(receiver,ele);
-    }
-    else {
+        addReplyBulk(receiver,value);
+    } else {
         /* BRPOPLPUSH */
-        robj *dobj = lookupKeyWrite(receiver->db,receiver->bstate.target);
-        if (dobj && checkType(receiver,dobj,REDIS_LIST)) return 0;
-
-        addReplyBulk(receiver,ele);
+        robj *dstobj =
+            lookupKeyWrite(receiver->db,dstkey);
+        if (!(dstobj &&
+             checkType(receiver,dstobj,REDIS_LIST)))
+        {
+            /* Propagate the RPOP operation. */
+            argv[0] = shared.rpop;
+            argv[1] = key;
+            propagate(server.rpopCommand,
+                db->id,argv,2,
+                REDIS_PROPAGATE_AOF|
+                REDIS_PROPAGATE_REPL);
+            rpoplpushHandlePush(receiver,dstkey,dstobj,
+                value);
+            /* Propagate the LPUSH operation. */
+            argv[0] = shared.lpush;
+            argv[1] = dstkey;
+            argv[2] = value;
+            propagate(server.lpushCommand,
+                db->id,argv,3,
+                REDIS_PROPAGATE_AOF|
+                REDIS_PROPAGATE_REPL);
+        } else {
+            /* BRPOPLPUSH failed because of wrong
+             * destination type. */
+            return REDIS_ERR;
+        }
+    }
+    return REDIS_OK;
+}
 
-        if (!handleClientsWaitingListPush(receiver, receiver->bstate.target, ele)) {
-            /* Create the list if the key does not exist */
-            if (!dobj) {
-                dobj = createZiplistObject();
-                dbAdd(receiver->db, receiver->bstate.target, dobj);
+/* This function should be called by Redis every time a single command,
+ * a MULTI/EXEC block, or a Lua script, terminated its execution after
+ * being called by a client.
+ *
+ * All the keys with at least one client blocked that received at least
+ * one new element via some PUSH operation are accumulated into
+ * the server.ready_keys list. This function will run the list and will
+ * serve clients accordingly. Note that the function will iterate again and
+ * again as a result of serving BRPOPLPUSH we can have new blocking clients
+ * to serve because of the PUSH side of BRPOPLPUSH. */
+void handleClientsBlockedOnLists(void) {
+    while(listLength(server.ready_keys) != 0) {
+        list *l;
+
+        /* Point server.ready_keys to a fresh list and save the current one
+         * locally. This way as we run the old list we are free to call
+         * signalListAsReady() that may push new elements in server.ready_keys
+         * when handling clients blocked into BRPOPLPUSH. */
+        l = server.ready_keys;
+        server.ready_keys = listCreate();
+
+        while(listLength(l) != 0) {
+            listNode *ln = listFirst(l);
+            readyList *rl = ln->value;
+
+            /* First of all remove this key from db->ready_keys so that
+             * we can safely call signalListAsReady() against this key. */
+            dictDelete(rl->db->ready_keys,rl->key);
+
+            /* If the key exists and it's a list, serve blocked clients
+             * with data. */
+            robj *o = lookupKeyWrite(rl->db,rl->key);
+            if (o != NULL && o->type == REDIS_LIST) {
+                dictEntry *de;
+
+                /* We serve clients in the same order they blocked for
+                 * this key, from the first blocked to the last. */
+                de = dictFind(rl->db->blocking_keys,rl->key);
+                if (de) {
+                    list *clients = dictGetVal(de);
+                    int numclients = listLength(clients);
+
+                    while(numclients--) {
+                        listNode *clientnode = listFirst(clients);
+                        redisClient *receiver = clientnode->value;
+                        robj *dstkey = receiver->bpop.target;
+                        int where = (receiver->lastcmd &&
+                                     receiver->lastcmd->proc == blpopCommand) ?
+                                    REDIS_HEAD : REDIS_TAIL;
+                        robj *value = listTypePop(o,where);
+
+                        if (value) {
+                            /* Protect receiver->bpop.target, that will be
+                             * freed by the next unblockClientWaitingData()
+                             * call. */
+                            if (dstkey) incrRefCount(dstkey);
+                            unblockClientWaitingData(receiver);
+
+                            if (serveClientBlockedOnList(receiver,
+                                rl->key,dstkey,rl->db,value,
+                                where) == REDIS_ERR)
+                            {
+                                /* If we failed serving the client we need
+                                 * to also undo the POP operation. */
+                                    listTypePush(o,value,where);
+                            }
+
+                            if (dstkey) decrRefCount(dstkey);
+                            decrRefCount(value);
+                        } else {
+                            break;
+                        }
+                    }
+                }
+                
+                if (listTypeLength(o) == 0) dbDelete(rl->db,rl->key);
+                /* We don't call signalModifiedKey() as it was already called
+                 * when an element was pushed on the list. */
             }
 
-            listTypePush(dobj, ele, REDIS_HEAD);
+            /* Free this item. */
+            decrRefCount(rl->key);
+            zfree(rl);
+            listDelNode(l,ln);
         }
+        listRelease(l); /* We have the new list on place at this point. */
     }
+}
+
+int getTimeoutFromObjectOrReply(redisClient *c, robj *object, time_t *timeout) {
+    long tval;
 
-    unblockClientWaitingData(receiver);
-    return 1;
+    if (getLongFromObjectOrReply(c,object,&tval,
+        "timeout is not an integer or out of range") != REDIS_OK)
+        return REDIS_ERR;
+
+    if (tval < 0) {
+        addReplyError(c,"timeout is negative");
+        return REDIS_ERR;
+    }
+
+    if (tval > 0) tval += server.unixtime;
+    *timeout = tval;
+
+    return REDIS_OK;
 }
 
 /* Blocking RPOP/LPOP */
@@ -824,9 +1005,8 @@ void blockingPopGenericCommand(redisClient *c, int where) {
     time_t timeout;
     int j;
 
-    if (checkTimeout(c, c->argv[c->argc - 1], &timeout) != REDIS_OK) {
+    if (getTimeoutFromObjectOrReply(c,c->argv[c->argc-1],&timeout) != REDIS_OK)
         return;
-    }
 
     for (j = 1; j < c->argc-1; j++) {
         o = lookupKeyWrite(c->db,c->argv[j]);
@@ -836,33 +1016,22 @@ void blockingPopGenericCommand(redisClient *c, int where) {
                 return;
             } else {
                 if (listTypeLength(o) != 0) {
-                    /* If the list contains elements fall back to the usual
-                     * non-blocking POP operation */
-                    robj *argv[2], **orig_argv;
-                    int orig_argc;
-
-                    /* We need to alter the command arguments before to call
-                     * popGenericCommand() as the command takes a single key. */
-                    orig_argv = c->argv;
-                    orig_argc = c->argc;
-                    argv[1] = c->argv[j];
-                    c->argv = argv;
-                    c->argc = 2;
-
-                    /* Also the return value is different, we need to output
-                     * the multi bulk reply header and the key name. The
-                     * "real" command will add the last element (the value)
-                     * for us. If this souds like an hack to you it's just
-                     * because it is... */
-                    addReplyMultiBulkLen(c,2);
-                    addReplyBulk(c,argv[1]);
-
-                    popGenericCommand(c,where);
-
-                    /* Fix the client structure with the original stuff */
-                    c->argv = orig_argv;
-                    c->argc = orig_argc;
+                    /* Non empty list, this is like a non normal [LR]POP. */
+                    robj *value = listTypePop(o,where);
+                    redisAssert(value != NULL);
 
+                    addReplyMultiBulkLen(c,2);
+                    addReplyBulk(c,c->argv[j]);
+                    addReplyBulk(c,value);
+                    decrRefCount(value);
+                    if (listTypeLength(o) == 0) dbDelete(c->db,c->argv[j]);
+                    signalModifiedKey(c->db,c->argv[j]);
+                    server.dirty++;
+
+                    /* Replicate it as an [LR]POP instead of B[LR]POP. */
+                    rewriteClientCommandVector(c,2,
+                        (where == REDIS_HEAD) ? shared.lpop : shared.rpop,
+                        c->argv[j]);
                     return;
                 }
             }
@@ -877,28 +1046,9 @@ void blockingPopGenericCommand(redisClient *c, int where) {
     }
 
     /* If the list is empty or the key does not exists we must block */
-    if (timeout > 0) timeout += time(NULL);
     blockForKeys(c, c->argv + 1, c->argc - 2, timeout, NULL);
 }
 
-int checkTimeout(redisClient *c, robj *object, time_t *timeout) {
-    long long lltimeout;
-
-    if (getLongLongFromObject(object, &lltimeout) != REDIS_OK) {
-        addReplyError(c, "timeout is not an integer");
-        return REDIS_ERR;
-    }
-
-    if (lltimeout < 0) {
-        addReplyError(c, "timeout is negative");
-        return REDIS_ERR;
-    }
-
-    *timeout = lltimeout;
-
-    return REDIS_OK;
-}
-
 void blpopCommand(redisClient *c) {
     blockingPopGenericCommand(c,REDIS_HEAD);
 }
@@ -910,21 +1060,17 @@ void brpopCommand(redisClient *c) {
 void brpoplpushCommand(redisClient *c) {
     time_t timeout;
 
-    if (checkTimeout(c, c->argv[3], &timeout) != REDIS_OK) {
+    if (getTimeoutFromObjectOrReply(c,c->argv[3],&timeout) != REDIS_OK)
         return;
-    }
 
     robj *key = lookupKeyWrite(c->db, c->argv[1]);
 
     if (key == NULL) {
         if (c->flags & REDIS_MULTI) {
-
             /* Blocking against an empty list in a multi state
              * returns immediately. */
-            addReply(c, shared.nullmultibulk);
+            addReply(c, shared.nullbulk);
         } else {
-            if (timeout > 0) timeout += time(NULL);
-
             /* The list is empty and the client blocks. */
             blockForKeys(c, c->argv + 1, 1, timeout, c->argv[2]);
         }
@@ -932,10 +1078,9 @@ void brpoplpushCommand(redisClient *c) {
         if (key->type != REDIS_LIST) {
             addReply(c, shared.wrongtypeerr);
         } else {
-
             /* The list exists and has elements, so
              * the regular rpoplpushCommand is executed. */
-            redisAssert(listTypeLength(key) > 0);
+            redisAssertWithInfo(c,key,listTypeLength(key) > 0);
             rpoplpushCommand(c);
         }
     }