From 7c25a43adc67c4a8d08e930aa92f1c5575ec3646 Mon Sep 17 00:00:00 2001
From: Damian Janowski & Michel Martens <damian.janowski+soveran@gmail.com>
Date: Tue, 9 Nov 2010 10:31:02 -0300
Subject: [PATCH] Handle BRPOPLPUSH inside a transaction.

---
 src/t_list.c             | 62 ++++++++++++++++++++++++----------------
 tests/unit/type/list.tcl | 15 +++++++++-
 2 files changed, 51 insertions(+), 26 deletions(-)

diff --git a/src/t_list.c b/src/t_list.c
index 2dedf4811..d14de708f 100644
--- a/src/t_list.c
+++ b/src/t_list.c
@@ -790,23 +790,28 @@ int handleClientsWaitingListPush(redisClient *c, robj *key, robj *ele) {
     receiver = ln->value;
 
     if (receiver->bstate.target == NULL) {
-      addReplyMultiBulkLen(receiver,2);
-      addReplyBulk(receiver,key);
-      addReplyBulk(receiver,ele);
+        /* BRPOP/BLPOP return a multi-bulk with the name
+         * of the popped list */
+        addReplyMultiBulkLen(receiver,2);
+        addReplyBulk(receiver,key);
+        addReplyBulk(receiver,ele);
     }
     else {
-      robj *dobj = lookupKeyWrite(receiver->db,receiver->bstate.target);
-      if (dobj && checkType(receiver,dobj,REDIS_LIST)) return 0;
+        /* BRPOPLPUSH */
+        robj *dobj = lookupKeyWrite(receiver->db,receiver->bstate.target);
+        if (dobj && checkType(receiver,dobj,REDIS_LIST)) return 0;
 
-      addReplyBulk(receiver,ele);
+        addReplyBulk(receiver,ele);
 
-      /* Create the list if the key does not exist */
-      if (!dobj) {
-          dobj = createZiplistObject();
-          dbAdd(receiver->db,receiver->bstate.target,dobj);
-      }
+        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);
+            }
 
-      listTypePush(dobj,ele,REDIS_HEAD);
+            listTypePush(dobj, ele, REDIS_HEAD);
+        }
     }
 
     unblockClientWaitingData(receiver);
@@ -880,13 +885,13 @@ 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;
+        addReplyError(c, "timeout is not an integer");
+        return REDIS_ERR;
     }
-    
+
     if (lltimeout < 0) {
-      addReplyError(c, "timeout is negative");
-      return REDIS_ERR;
+        addReplyError(c, "timeout is negative");
+        return REDIS_ERR;
     }
 
     *timeout = lltimeout;
@@ -911,20 +916,27 @@ void brpoplpushCommand(redisClient *c) {
 
     robj *key = lookupKeyWrite(c->db, c->argv[1]);
 
-
     if (key == NULL) {
-        // block
         if (c->flags & REDIS_MULTI) {
-            addReply(c,shared.nullmultibulk);
+
+            /* Blocking against an empty list in a multi state
+             * returns immediately. */
+            addReply(c, shared.nullmultibulk);
         } 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]);
         }
-    } else if (key->type != REDIS_LIST) {
-        addReply(c, shared.wrongtypeerr);
     } else {
-        // The list exists and has elements.
-        redisAssert(listTypeLength(key) > 0);
-        rpoplpushCommand(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);
+            rpoplpushCommand(c);
+        }
     }
 }
diff --git a/tests/unit/type/list.tcl b/tests/unit/type/list.tcl
index a2d0edf6d..62ea159dd 100644
--- a/tests/unit/type/list.tcl
+++ b/tests/unit/type/list.tcl
@@ -152,6 +152,19 @@ start_server {
         assert_equal {foo} [r lrange target 0 -1]
     }
 
+    test "BRPOPLPUSH with a client BLPOPing the target list" {
+        set rd [redis_deferring_client]
+        set rd2 [redis_deferring_client]
+        r del blist target
+        $rd2 blpop target 0
+        $rd brpoplpush blist target 0
+        after 1000
+        r rpush blist foo
+        assert_equal foo [$rd read]
+        assert_equal {target foo} [$rd2 read]
+        assert_equal 0 [r exists target]
+    }
+
     test "BRPOPLPUSH with wrong source type" {
         set rd [redis_deferring_client]
         r del blist target
@@ -178,7 +191,7 @@ start_server {
         assert_equal {foo} [r lrange blist 0 -1]
     }
 
-    test {BRPOPLPUSH inside a transaction} {
+    test "BRPOPLPUSH inside a transaction" {
         r del xlist target
         r lpush xlist foo
         r lpush xlist bar