From c1db214eeb2b7385c32889e17748429fcbe5cbae Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Wed, 29 Feb 2012 14:41:57 +0100
Subject: [PATCH] Better implementation for BRPOP/BLPOP in the non blocking
 case.

---
 src/redis.c  |  2 ++
 src/redis.h  |  2 +-
 src/t_list.c | 44 +++++++++++++++-----------------------------
 3 files changed, 18 insertions(+), 30 deletions(-)

diff --git a/src/redis.c b/src/redis.c
index 78067d31..64df9073 100644
--- a/src/redis.c
+++ b/src/redis.c
@@ -852,6 +852,8 @@ void createSharedObjects(void) {
     shared.psubscribebulk = createStringObject("$10\r\npsubscribe\r\n",17);
     shared.punsubscribebulk = createStringObject("$12\r\npunsubscribe\r\n",19);
     shared.del = createStringObject("DEL",3);
+    shared.rpop = createStringObject("RPOP",4);
+    shared.lpop = createStringObject("LPOP",4);
     for (j = 0; j < REDIS_SHARED_INTEGERS; j++) {
         shared.integers[j] = createObject(REDIS_STRING,(void*)(long)j);
         shared.integers[j]->encoding = REDIS_ENCODING_INT;
diff --git a/src/redis.h b/src/redis.h
index c2617870..cccdcc81 100644
--- a/src/redis.h
+++ b/src/redis.h
@@ -365,7 +365,7 @@ struct sharedObjectsStruct {
     *select0, *select1, *select2, *select3, *select4,
     *select5, *select6, *select7, *select8, *select9,
     *messagebulk, *pmessagebulk, *subscribebulk, *unsubscribebulk,
-    *psubscribebulk, *punsubscribebulk, *del,
+    *psubscribebulk, *punsubscribebulk, *del, *rpop, *lpop,
     *integers[REDIS_SHARED_INTEGERS],
     *mbulkhdr[REDIS_SHARED_BULKHDR_LEN], /* "*<value>\r\n" */
     *bulkhdr[REDIS_SHARED_BULKHDR_LEN];  /* "$<value>\r\n" */
diff --git a/src/t_list.c b/src/t_list.c
index d6e28b7e..2be8074a 100644
--- a/src/t_list.c
+++ b/src/t_list.c
@@ -933,36 +933,22 @@ 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 */
-                    struct redisCommand *orig_cmd;
-                    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;
-                    orig_cmd = c->cmd;
-                    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;
-                    c->cmd = orig_cmd;
+                    /* 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;
                 }
             }
-- 
2.47.2