Client should not block multiple times on the same key.

[redis.git] / src / t_list.c

diff --git a/src/t_list.c b/src/t_list.c
index 77e40eb6b215dbe69036bc7ac00595e688072b4d..1bd81c2e1c8c2075d49a44fec20ff9fd2dd7a8b8 100644 (file)
--- a/src/t_list.c
+++ b/src/t_list.c
@@ -1,3 +1,32 @@
+/*
+ * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
 #include "redis.h"
 
 void signalListAsReady(redisClient *c, robj *key);
@@ -724,22 +753,33 @@ void rpoplpushCommand(redisClient *c) {
 /* Set a client in blocking mode for the specified key, with the specified
  * timeout */
 void blockForKeys(redisClient *c, robj **keys, int numkeys, time_t timeout, robj *target) {
+    dict *added;
     dictEntry *de;
     list *l;
-    int j;
+    int j, i;
 
     c->bpop.keys = zmalloc(sizeof(robj*)*numkeys);
-    c->bpop.count = numkeys;
     c->bpop.timeout = timeout;
     c->bpop.target = target;
 
-    if (target != NULL) {
-        incrRefCount(target);
-    }
+    if (target != NULL) incrRefCount(target);
+
+    /* Create a dictionary that we use to avoid adding duplicated keys
+     * in case the user calls something like: "BLPOP foo foo foo 0".
+     * The rest of the implementation is simpler if we know there are no
+     * duplications in the key waiting list. */
+    added = dictCreate(&setDictType,NULL);
 
+    i = 0; /* The index for c->bpop.keys[...], we can't use the j loop
+              variable as the list of keys may have duplicated elements. */
     for (j = 0; j < numkeys; j++) {
+        /* Add the key in the "added" dictionary to make sure there are 
+         * no duplicated keys. */
+        if (dictAdd(added,keys[j],NULL) != DICT_OK) continue;
+        incrRefCount(keys[j]);
+
         /* Add the key in the client structure, to map clients -> keys */
-        c->bpop.keys[j] = keys[j];
+        c->bpop.keys[i++] = keys[j];
         incrRefCount(keys[j]);
 
         /* And in the other "side", to map keys -> clients */
@@ -757,9 +797,12 @@ void blockForKeys(redisClient *c, robj **keys, int numkeys, time_t timeout, robj
         }
         listAddNodeTail(l,c);
     }
+    c->bpop.count = i;
+
     /* Mark the client as a blocked client */
     c->flags |= REDIS_BLOCKED;
     server.bpop_blocked_clients++;
+    dictRelease(added);
 }
 
 /* Unblock a client that's waiting in a blocking operation such as BLPOP */