From baa14ef913032baf34645faeae80f5cd6895f97a Mon Sep 17 00:00:00 2001
From: Michel Martens & Damian Janowski <michel+djanowski@soveran.com>
Date: Mon, 29 Nov 2010 23:47:45 -0300
Subject: [PATCH] Fix BRPOPLPUSH behavior for all use cases.

---
 src/t_list.c             | 20 +++++++++----------
 tests/unit/type/list.tcl | 43 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 10 deletions(-)

diff --git a/src/t_list.c b/src/t_list.c
index 0da70a04..ceed70c3 100644
--- a/src/t_list.c
+++ b/src/t_list.c
@@ -748,10 +748,6 @@ void unblockClientWaitingData(redisClient *c) {
         decrRefCount(c->bpop.keys[j]);
     }
 
-    if (c->bpop.target != NULL) {
-        decrRefCount(c->bpop.target);
-    }
-
     /* Cleanup the client structure */
     zfree(c->bpop.keys);
     c->bpop.keys = NULL;
@@ -789,7 +785,11 @@ int handleClientsWaitingListPush(redisClient *c, robj *key, robj *ele) {
     redisAssert(ln != NULL);
     receiver = ln->value;
 
-    if (receiver->bpop.target == NULL) {
+    robj *target = receiver->bpop.target;
+
+    unblockClientWaitingData(receiver);
+
+    if (target == NULL) {
         /* BRPOP/BLPOP return a multi-bulk with the name
          * of the popped list */
         addReplyMultiBulkLen(receiver,2);
@@ -797,23 +797,23 @@ int handleClientsWaitingListPush(redisClient *c, robj *key, robj *ele) {
         addReplyBulk(receiver,ele);
     } else {
         /* BRPOPLPUSH */
-        robj *dobj = lookupKeyWrite(receiver->db,receiver->bpop.target);
+        robj *dobj = lookupKeyWrite(receiver->db,target);
         if (dobj && checkType(receiver,dobj,REDIS_LIST)) return 0;
 
         addReplyBulk(receiver,ele);
 
-        if (!handleClientsWaitingListPush(receiver, receiver->bpop.target, ele)) {
+        if (!handleClientsWaitingListPush(receiver, target, ele)) {
             /* Create the list if the key does not exist */
             if (!dobj) {
                 dobj = createZiplistObject();
-                dbAdd(receiver->db, receiver->bpop.target, dobj);
+                dbAdd(receiver->db, target, dobj);
             }
-
             listTypePush(dobj, ele, REDIS_HEAD);
         }
+
+        decrRefCount(target);
     }
 
-    unblockClientWaitingData(receiver);
     return 1;
 }
 
diff --git a/tests/unit/type/list.tcl b/tests/unit/type/list.tcl
index 62ea159d..36164433 100644
--- a/tests/unit/type/list.tcl
+++ b/tests/unit/type/list.tcl
@@ -191,6 +191,49 @@ start_server {
         assert_equal {foo} [r lrange blist 0 -1]
     }
 
+    test "linked BRPOPLPUSH" {
+      set rd1 [redis_deferring_client]
+      set rd2 [redis_deferring_client]
+
+      r del list1 list2 list3
+
+      $rd1 brpoplpush list1 list2 0
+      $rd2 brpoplpush list2 list3 0
+
+      r rpush list1 foo
+
+      assert_equal {} [r lrange list1 0 -1]
+      assert_equal {} [r lrange list2 0 -1]
+      assert_equal {foo} [r lrange list3 0 -1]
+    }
+
+    test "circular BRPOPLPUSH" {
+      set rd1 [redis_deferring_client]
+      set rd2 [redis_deferring_client]
+
+      r del list1 list2
+
+      $rd1 brpoplpush list1 list2 0
+      $rd2 brpoplpush list2 list1 0
+
+      r rpush list1 foo
+
+      assert_equal {foo} [r lrange list1 0 -1]
+      assert_equal {} [r lrange list2 0 -1]
+    }
+
+    test "self-referential BRPOPLPUSH" {
+      set rd [redis_deferring_client]
+
+      r del blist
+
+      $rd brpoplpush blist blist 0
+
+      r rpush blist foo
+
+      assert_equal {foo} [r lrange blist 0 -1]
+    }
+
     test "BRPOPLPUSH inside a transaction" {
         r del xlist target
         r lpush xlist foo
-- 
2.45.2