propagate PUBLISH messages using the redis cluster nodes bus. Still need to process the incoming packets of that type. Work in progress.

src/cluster.c

@@ -666,7 +666,7 @@ int clusterProcessPacket(clusterLink *link) {
             clusterSaveConfigOrDie();
         }
     } else {
-        redisLog(REDIS_NOTICE,"Received unknown packet type: %d", type);
+        redisLog(REDIS_WARNING,"Received unknown packet type: %d", type);
     }
     return 1;
 }
@@ -759,6 +759,22 @@ void clusterSendMessage(clusterLink *link, unsigned char *msg, size_t msglen) {
     link->sndbuf = sdscatlen(link->sndbuf, msg, msglen);
 }
 
+/* Send a message to all the nodes with a reliable link */
+void clusterBroadcastMessage(void *buf, size_t len) {
+    dictIterator *di;
+    dictEntry *de;
+
+    di = dictGetIterator(server.cluster.nodes);
+    while((de = dictNext(di)) != NULL) {
+        clusterNode *node = dictGetEntryVal(de);
+
+        if (!node->link) continue;
+        if (node->flags & (REDIS_NODE_MYSELF|REDIS_NODE_NOADDR)) continue;
+        clusterSendMessage(node->link,buf,len);
+    }
+    dictReleaseIterator(di);
+}
+
 /* Build the message header */
 void clusterBuildMessageHdr(clusterMsg *hdr, int type) {
     int totlen;
@@ -843,20 +859,48 @@ void clusterSendPing(clusterLink *link, int type) {
     clusterSendMessage(link,buf,totlen);
 }
 
-/* Send a message to all the nodes with a reliable link */
-void clusterBroadcastMessage(void *buf, size_t len) {
-    dictIterator *di;
-    dictEntry *de;
+/* Send a PUBLISH message.
+ *
+ * If link is NULL, then the message is broadcasted to the whole cluster. */
+void clusterSendPublish(clusterLink *link, robj *channel, robj *message) {
+    unsigned char buf[4096], *payload;
+    clusterMsg *hdr = (clusterMsg*) buf;
+    uint32_t totlen;
+    uint32_t channel_len, message_len;
 
-    di = dictGetIterator(server.cluster.nodes);
-    while((de = dictNext(di)) != NULL) {
-        clusterNode *node = dictGetEntryVal(de);
+    channel = getDecodedObject(channel);
+    message = getDecodedObject(message);
+    channel_len = sdslen(channel->ptr);
+    message_len = sdslen(message->ptr);
 
-        if (!node->link) continue;
-        if (node->flags & (REDIS_NODE_MYSELF|REDIS_NODE_NOADDR)) continue;
-        clusterSendMessage(node->link,buf,len);
+    clusterBuildMessageHdr(hdr,CLUSTERMSG_TYPE_PUBLISH);
+    totlen = sizeof(clusterMsg)-sizeof(union clusterMsgData);
+    totlen += sizeof(clusterMsgDataPublish) + channel_len + message_len;
+
+    hdr->data.publish.msg.channel_len = htonl(channel_len);
+    hdr->data.publish.msg.message_len = htonl(message_len);
+    hdr->totlen = htonl(totlen);
+
+    /* Try to use the local buffer if possible */
+    if (totlen < sizeof(buf)) {
+        payload = buf;
+    } else {
+        payload = zmalloc(totlen);
+        hdr = (clusterMsg*) payload;
+        memcpy(payload,hdr,sizeof(hdr));
     }
-    dictReleaseIterator(di);
+    memcpy(hdr->data.publish.msg.bulk_data,channel->ptr,sdslen(channel->ptr));
+    memcpy(hdr->data.publish.msg.bulk_data+sdslen(channel->ptr),
+        message->ptr,sdslen(message->ptr));
+
+    if (link)
+        clusterSendMessage(link,payload,totlen);
+    else
+        clusterBroadcastMessage(payload,totlen);
+
+    decrRefCount(channel);
+    decrRefCount(message);
+    if (payload != buf) zfree(payload);
 }
 
 /* Send a FAIL message to all the nodes we are able to contact.
@@ -873,6 +917,17 @@ void clusterSendFail(char *nodename) {
     clusterBroadcastMessage(buf,ntohl(hdr->totlen));
 }
 
+/* -----------------------------------------------------------------------------
+ * CLUSTER Pub/Sub support
+ *
+ * For now we do very little, just propagating PUBLISH messages across the whole
+ * cluster. In the future we'll try to get smarter and avoiding propagating those
+ * messages to hosts without receives for a given channel.
+ * -------------------------------------------------------------------------- */
+void clusterPropagatePublish(robj *channel, robj *message) {
+    clusterSendPublish(NULL, channel, message);
+}
+
 /* -----------------------------------------------------------------------------
  * CLUSTER cron job
  * -------------------------------------------------------------------------- */

src/pubsub.c

@@ -263,5 +263,6 @@ void punsubscribeCommand(redisClient *c) {
 
 void publishCommand(redisClient *c) {
     int receivers = pubsubPublishMessage(c->argv[1],c->argv[2]);
+    if (server.cluster_enabled) clusterPropagatePublish(c->argv[1],c->argv[2]);
     addReplyLongLong(c,receivers);
 }

src/redis.h

@@ -445,6 +445,7 @@ typedef struct {
 #define CLUSTERMSG_TYPE_PONG 1          /* Pong (reply to Ping) */
 #define CLUSTERMSG_TYPE_MEET 2          /* Meet "let's join" message */
 #define CLUSTERMSG_TYPE_FAIL 3          /* Mark node xxx as failing */
+#define CLUSTERMSG_TYPE_PUBLISH 4       /* Pub/Sub Publish propatagion */
 
 /* Initially we don't know our "name", but we'll find it once we connect
  * to the first node, using the getsockname() function. Then we'll use this
@@ -463,16 +464,28 @@ typedef struct {
     char nodename[REDIS_CLUSTER_NAMELEN];
 } clusterMsgDataFail;
 
+typedef struct {
+    uint32_t channel_len;
+    uint32_t message_len;
+    unsigned char bulk_data[8]; /* defined as 8 just for alignment concerns. */
+} clusterMsgDataPublish;
+
 union clusterMsgData {
     /* PING, MEET and PONG */
     struct {
         /* Array of N clusterMsgDataGossip structures */
         clusterMsgDataGossip gossip[1];
     } ping;
+
     /* FAIL */
     struct {
         clusterMsgDataFail about;
     } fail;
+
+    /* PUBLISH */
+    struct {
+        clusterMsgDataPublish msg;
+    } publish;
 };
 
 typedef struct {
@@ -976,6 +989,7 @@ clusterNode *createClusterNode(char *nodename, int flags);
 int clusterAddNode(clusterNode *node);
 void clusterCron(void);
 clusterNode *getNodeByQuery(redisClient *c, struct redisCommand *cmd, robj **argv, int argc, int *hashslot, int *ask);
+void clusterPropagatePublish(robj *channel, robj *message);
 
 /* Scripting */
 void scriptingInit(void);