redis_recycle.diff

diff --git a/src/db.c b/src/db.c
index 669fba1..6ae83d3 100644
--- a/src/db.c
+++ b/src/db.c
@@ -514,7 +514,8 @@ void propagateExpire(redisDb *db, robj *key) {
     argv[0] = createStringObject("DEL",3);
     argv[1] = key;
     incrRefCount(key);
-
+    if (db->expire_channel)
+        pubsubPublishMessage(db->expire_channel,key);
     if (server.appendonly)
         feedAppendOnlyFile(server.delCommand,db->id,argv,2);
     if (listLength(server.slaves))
@@ -615,3 +616,27 @@ void persistCommand(redisClient *c) {
         }
     }
 }
+
+void recycleCommand(redisClient *c) {
+    c->db->expire_channel = c->argv[1];
+    subscribeCommand(c);
+}
+
+void recycletoCommand(redisClient *c) {
+    if (c->db->expire_channel == NULL) {
+        addReply(c,shared.ok);
+    } else {
+        addReply(c,c->db->expire_channel);
+    }
+}
+
+void disposeCommand(redisClient *c) {
+    if (c->db->expire_channel == NULL) {
+        addReply(c,shared.err);
+    } else {
+        c->argc = 1;
+        c->argv[1] = c->db->expire_channel;
+        c->db->expire_channel = NULL;
+        unsubscribeCommand(c);
+    }
+}
diff --git a/src/help.h b/src/help.h
index 51613c9..ba1df07 100644
--- a/src/help.h
+++ b/src/help.h
@@ -632,7 +632,22 @@ struct commandHelp {
     "destination numkeys key [key ...] [WEIGHTS weight] [AGGREGATE SUM|MIN|MAX]",
     "Add multiple sorted sets and store the resulting sorted set in a new key",
     4,
-    "1.3.10" }
+    "1.3.10" },
+    { "RECYCLE",
+    "channel",
+    "Define a Dead Letter Channel to publish expired keys to",
+    6,
+    "0.1" },
+    { "RECYCLETO",
+    "-",
+    "Return the Dead Letter Channel expired keys is published to",
+    6,
+    "0.1" },
+    { "DISPOSE",
+    "-",
+    "Remove a registered Dead Letter Channel and stop broadcasting key expiry",
+    6,
+    "0.1" }
 };
 
 #endif
diff --git a/src/redis.c b/src/redis.c
index 5548d1c..52fc749 100644
--- a/src/redis.c
+++ b/src/redis.c
@@ -187,7 +187,10 @@ struct redisCommand redisCommandTable[] = {
     {"punsubscribe",punsubscribeCommand,-1,0,NULL,0,0,0,0,0},
     {"publish",publishCommand,3,REDIS_CMD_FORCE_REPLICATION,NULL,0,0,0,0,0},
     {"watch",watchCommand,-2,0,NULL,0,0,0,0,0},
-    {"unwatch",unwatchCommand,1,0,NULL,0,0,0,0,0}
+    {"unwatch",unwatchCommand,1,0,NULL,0,0,0,0,0},
+    {"recycle",recycleCommand,2,0,NULL,1,1,1,0,0},
+    {"recycleto",recycletoCommand,1,0,NULL,0,0,0,0,0},
+    {"dispose",disposeCommand,1,0,NULL,0,0,0,0,0}
 };
 
 /*============================ Utility functions ============================ */
@@ -886,6 +889,7 @@ void initServer() {
         server.db[j].expires = dictCreate(&keyptrDictType,NULL);
         server.db[j].blocking_keys = dictCreate(&keylistDictType,NULL);
         server.db[j].watched_keys = dictCreate(&keylistDictType,NULL);
+        server.db[j].expire_channel = NULL;
         if (server.ds_enabled) {
             server.db[j].io_keys = dictCreate(&keylistDictType,NULL);
             server.db[j].io_negcache = dictCreate(&setDictType,NULL);
@@ -1052,8 +1056,9 @@ int processCommand(redisClient *c) {
     if ((dictSize(c->pubsub_channels) > 0 || listLength(c->pubsub_patterns) > 0)
         &&
         cmd->proc != subscribeCommand && cmd->proc != unsubscribeCommand &&
-        cmd->proc != psubscribeCommand && cmd->proc != punsubscribeCommand) {
-        addReplyError(c,"only (P)SUBSCRIBE / (P)UNSUBSCRIBE / QUIT allowed in this context");
+        cmd->proc != psubscribeCommand && cmd->proc != punsubscribeCommand &&
+        cmd->proc != disposeCommand) {
+        addReplyError(c,"only (P)SUBSCRIBE / (P)UNSUBSCRIBE / QUIT / DISPOSE allowed in this context");
         return REDIS_OK;
     }
 
diff --git a/src/redis.h b/src/redis.h
index 5ae9cc1..886bb40 100644
--- a/src/redis.h
+++ b/src/redis.h
@@ -279,6 +279,7 @@ typedef struct redisDb {
     dict *io_negcache;          /* Negative caching for disk store */
     dict *io_queued;            /* Queued IO operations hash table */
     dict *watched_keys;         /* WATCHED keys for MULTI/EXEC CAS */
+    robj *expire_channel;       /* Dead Letter Channel for expired keys */
     int id;
 } redisDb;
 
@@ -873,6 +874,7 @@ int pubsubUnsubscribeAllChannels(redisClient *c, int notify);
 int pubsubUnsubscribeAllPatterns(redisClient *c, int notify);
 void freePubsubPattern(void *p);
 int listMatchPubsubPattern(void *a, void *b);
+int pubsubPublishMessage(robj *channel, robj *message);
 
 /* Utility functions */
 int stringmatchlen(const char *pattern, int patternLen,
@@ -1032,6 +1034,9 @@ void punsubscribeCommand(redisClient *c);
 void publishCommand(redisClient *c);
 void watchCommand(redisClient *c);
 void unwatchCommand(redisClient *c);
+void recycleCommand(redisClient *c);
+void recycletoCommand(redisClient *c);
+void disposeCommand(redisClient *c);
 
 #if defined(__GNUC__)
 void *calloc(size_t count, size_t size) __attribute__ ((deprecated));
diff --git a/tests/unit/pubsub.tcl b/tests/unit/pubsub.tcl
index c8b547b..c22952e 100644
--- a/tests/unit/pubsub.tcl
+++ b/tests/unit/pubsub.tcl
@@ -192,4 +192,30 @@ start_server {tags {"pubsub"}} {
         # clean up clients
         $rd1 close
     }
-}
\ No newline at end of file
+
+    test "RECYCLE on expire" {
+        # Set keys with a TTL and recycle them to a dead letter channel
+        assert_equal "OK" [r set x foo]
+        assert_equal "OK" [r set y bar]
+        assert_equal 1 [r expire x 1]
+        assert_equal 1 [r expire y 2]
+        assert_equal "subscribe expired 1" [r recycle expired]
+
+        after 3000
+        assert_equal {message expired x} [r read]
+        assert_equal {message expired y} [r read]
+    }
+
+    test "DISPOSE with a dead letter channel set" {
+        assert_equal "unsubscribe expired 0" [r dispose]
+    }
+
+    test "DISPOSE without a dead letter channel set" {
+        catch {r dispose} err
+        set _ $err
+    } {ERR}
+
+    test {RECYCLETO without a dead letter channel set} {
+        r recycleto
+    } {OK}
+}