Tracking: BCAST: registration in the prefix table.

src/networking.c

@@ -154,7 +154,7 @@ client *createClient(connection *conn) {
     c->peerid = NULL;
     c->client_list_node = NULL;
     c->client_tracking_redirection = 0;
-    c->client_tracking_prefix_nodes = NULL;
+    c->client_tracking_prefixes = NULL;
     c->auth_callback = NULL;
     c->auth_callback_privdata = NULL;
     c->auth_module = NULL;
@@ -2028,7 +2028,6 @@ int clientSetNameOrReply(client *c, robj *name) {
 void clientCommand(client *c) {
     listNode *ln;
     listIter li;
-    client *client;
 
     if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"help")) {
         const char *help[] = {
@@ -2142,7 +2141,7 @@ NULL
         /* Iterate clients killing all the matching clients. */
         listRewind(server.clients,&li);
         while ((ln = listNext(&li)) != NULL) {
-            client = listNodeValue(ln);
+            client *client = listNodeValue(ln);
             if (addr && strcmp(getClientPeerId(client),addr) != 0) continue;
             if (type != -1 && getClientType(client) != type) continue;
             if (id != 0 && client->id != id) continue;
@@ -2229,7 +2228,7 @@ NULL
         size_t numprefix = 0;
 
         /* Parse the options. */
-        if (for int j = 3; j < argc; j++) {
+        for (int j = 3; j < c->argc; j++) {
             int moreargs = (c->argc-1) - j;
 
             if (!strcasecmp(c->argv[j]->ptr,"redirect") && moreargs) {
@@ -2246,10 +2245,10 @@ NULL
                 }
             } else if (!strcasecmp(c->argv[j]->ptr,"bcast")) {
                 bcast++;
-            } else if (!strcasecmp(c->argv[j]->ptr,"prefix") && morearg) {
+            } else if (!strcasecmp(c->argv[j]->ptr,"prefix") && moreargs) {
                 j++;
-                prefix = zrealloc(sizeof(robj*)*(numprefix+1));
-                prefix[numprefix++] = argv[j];
+                prefix = zrealloc(prefix,sizeof(robj*)*(numprefix+1));
+                prefix[numprefix++] = c->argv[j];
             } else {
                 addReply(c,shared.syntaxerr);
                 return;
@@ -2259,16 +2258,16 @@ NULL
         /* Make sure options are compatible among each other and with the
          * current state of the client. */
         if (!bcast && numprefix) {
-            addReplyError("PREFIX option requires BCAST mode to be enabled");
+            addReplyError(c,"PREFIX option requires BCAST mode to be enabled");
             zfree(prefix);
             return;
         }
 
-        if (client->flags & CLIENT_TRACKING) {
-            int oldbcast = !!client->flags & CLIENT_TRACKING_BCAST;
+        if (c->flags & CLIENT_TRACKING) {
+            int oldbcast = !!c->flags & CLIENT_TRACKING_BCAST;
             if (oldbcast != bcast) {
             }
-            addReplyError(
+            addReplyError(c,
                 "You can't switch BCAST mode on/off before disabling "
                 "tracking for this client, and then re-enabling it with "
                 "a different mode.");

src/server.h

@@ -823,12 +823,9 @@ typedef struct client {
      * invalidation messages for keys fetched by this client will be send to
      * the specified client ID. */
     uint64_t client_tracking_redirection;
-    list *client_tracking_prefix_nodes; /* This list contains listNode pointers
-                                           to the nodes we have in every list
-                                           of clients in the tracking bcast
-                                           table. This way we can remove our
-                                           client in O(1) for each list. */
-
+    rax *client_tracking_prefixes; /* A dictionary of prefixes we are already
+                                      subscribed to in BCAST mode, in the
+                                      context of client side caching. */
     /* Response buffer */
     int bufpos;
     char buf[PROTO_REPLY_CHUNK_BYTES];

src/tracking.c

@@ -49,6 +49,15 @@ uint64_t TrackingTableTotalItems = 0; /* Total number of IDs stored across
                                          are using server side for CSC. */
 robj *TrackingChannelName;
 
+/* This is the structure that we have as value of the PrefixTable, and
+ * represents the list of keys modified, and the list of clients that need
+ * to be notified, for a given prefix. */
+typedef struct bcastState {
+    rax *keys;      /* Keys modified in the current event loop cycle. */
+    rax *clients;   /* Clients subscribed to the notification events for this
+                       prefix. */
+} bcastState;
+
 /* Remove the tracking state from the client 'c'. Note that there is not much
  * to do for us here, if not to decrement the counter of the clients in
  * tracking mode, because we just store the ID of the client in the tracking
@@ -56,9 +65,51 @@ robj *TrackingChannelName;
  * client with many entries in the table is removed, it would cost a lot of
  * time to do the cleanup. */
 void disableTracking(client *c) {
+    /* If this client is in broadcasting mode, we need to unsubscribe it
+     * from all the prefixes it is registered to. */
+    if (c->flags & CLIENT_TRACKING_BCAST) {
+        raxIterator ri;
+        raxStart(&ri,c->client_tracking_prefixes);
+        raxSeek(&ri,"^",NULL,0);
+        while(raxNext(&ri)) {
+            bcastState *bs = raxFind(PrefixTable,ri.key,ri.key_len);
+            serverAssert(bs != raxNotFound);
+            raxRemove(bs->clients,(unsigned char*)&c,sizeof(c),NULL);
+            /* Was it the last client? Remove the prefix from the
+             * table. */
+            if (raxSize(bs->clients) == 0) {
+                raxFree(bs->clients);
+                raxFree(bs->keys);
+                zfree(bs);
+                raxRemove(PrefixTable,ri.key,ri.key_len,NULL);
+            }
+        }
+        raxStop(&ri);
+    }
+
+    /* Clear flags and adjust the count. */
     if (c->flags & CLIENT_TRACKING) {
         server.tracking_clients--;
-        c->flags &= ~(CLIENT_TRACKING|CLIENT_TRACKING_BROKEN_REDIR);
+        c->flags &= ~(CLIENT_TRACKING|CLIENT_TRACKING_BROKEN_REDIR|
+                      CLIENT_TRACKING_BCAST);
+    }
+}
+
+/* Set the client 'c' to track the prefix 'prefix'. If the client 'c' is
+ * already registered for the specified prefix, no operation is performed. */
+void enableBcastTrackingForPrefix(client *c, char *prefix, size_t plen) {
+    bcastState *bs = raxFind(PrefixTable,(unsigned char*)prefix,sdslen(prefix));
+    /* If this is the first client subscribing to such prefix, create
+     * the prefix in the table. */
+    if (bs == raxNotFound) {
+        bs = zmalloc(sizeof(*bs));
+        bs->keys = raxNew();
+        bs->clients = raxNew();
+        raxInsert(PrefixTable,(unsigned char*)prefix,plen,bs,NULL);
+    }
+    if (raxTryInsert(bs->clients,(unsigned char*)&c,sizeof(c),NULL,NULL)) {
+        raxInsert(c->client_tracking_prefixes,
+                  (unsigned char*)prefix,plen,NULL,NULL);
     }
 }
 
@@ -83,9 +134,9 @@ void enableTracking(client *c, uint64_t redirect_to, int bcast, robj **prefix, s
     if (bcast) {
         c->flags |= CLIENT_TRACKING_BCAST;
         if (numprefix == 0) enableBcastTrackingForPrefix(c,"",0);
-        for (int j = 0; j < numprefix; j++) {
+        for (size_t j = 0; j < numprefix; j++) {
             sds sdsprefix = prefix[j]->ptr;
-            enableBcastTrackingForPrefix(c,sdsprefix,sdslen(prefix));
+            enableBcastTrackingForPrefix(c,sdsprefix,sdslen(sdsprefix));
         }
     }
 }