CG: consumer lookup + initial streamReplyWithRange() work to supprot CG.

src/t_stream.c

@@ -42,6 +42,7 @@
 
 void streamFreeCG(streamCG *cg);
 streamCG *streamLookupCG(stream *s, sds groupname);
+streamConsumer *streamLookupConsumer(streamCG *cg, sds name);
 
 /* -----------------------------------------------------------------------
  * Low level stream encoding: a radix tree of listpacks.
@@ -659,8 +660,19 @@ void streamIteratorStop(streamIterator *si) {
  * receive is between start and end inclusive, if 'count' is non zero, no more
  * than 'count' elemnets are sent. The 'end' pointer can be NULL to mean that
  * we want all the elements from 'start' till the end of the stream. If 'rev'
- * is non zero, elements are produced in reversed order from end to start. */
-size_t streamReplyWithRange(client *c, stream *s, streamID *start, streamID *end, size_t count, int rev) {
+ * is non zero, elements are produced in reversed order from end to start.
+ *
+ * If group and consumer are not NULL, the function performs additional work:
+ * 1. It updates the last delivered ID in the group in case we are
+ *    sending IDs greater than the current last ID.
+ * 2. If the requested IDs are already assigned to some other consumer, the
+ *    function will not return it to the client.
+ * 3. An entry in the pending list will be created for every entry delivered
+ *    for the first time to this consumer. This is only performed if
+ *    consumer != NULL, so in order to implement the XREADGROUP NOACK option
+ *    no consumer is passed to this function.
+ */
+size_t streamReplyWithRange(client *c, stream *s, streamID *start, streamID *end, size_t count, int rev, streamCG *group, streamConsumer *consumer) {
     void *arraylen_ptr = addDeferredMultiBulkLength(c);
     size_t arraylen = 0;
     streamIterator si;
@@ -903,7 +915,7 @@ void xrangeGenericCommand(client *c, int rev) {
     if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.emptymultibulk)) == NULL
         || checkType(c,o,OBJ_STREAM)) return;
     s = o->ptr;
-    streamReplyWithRange(c,s,&startid,&endid,count,rev);
+    streamReplyWithRange(c,s,&startid,&endid,count,rev,NULL,NULL);
 }
 
 /* XRANGE key start end [COUNT <n>] */
@@ -1063,13 +1075,18 @@ void xreadCommand(client *c) {
              * so start from the next ID, since we want only messages with
              * IDs greater than start. */
             streamID start = *gt;
-            start.seq++; /* Can't overflow, it's an uint64_t */
+            start.seq++; /* uint64_t can't overflow in this context. */
 
             /* Emit the two elements sub-array consisting of the name
              * of the stream and the data we extracted from it. */
             addReplyMultiBulkLen(c,2);
             addReplyBulk(c,c->argv[i+streams_arg]);
-            streamReplyWithRange(c,s,&start,NULL,count,0);
+            streamConsumer *consumer = NULL;
+            if (groups) consumer = streamLookupConsumer(groups[i],
+                                                        consumername->ptr);
+            streamReplyWithRange(c,s,&start,NULL,count,0,
+                                 groups ? groups[i] : NULL,
+                                 consumer);
         }
     }
 
@@ -1118,6 +1135,7 @@ void streamNotAckedFree(streamNotAcked *na) {
 }
 
 void streamConsumerFree(streamConsumer *sc) {
+    zfree(sc->name);
     zfree(sc);
 }
 
@@ -1154,6 +1172,22 @@ streamCG *streamLookupCG(stream *s, sds groupname) {
     return (cg == raxNotFound) ? NULL : cg;
 }
 
+/* Lookup the consumer with the specified name in the group 'cg': if the
+ * consumer does not exist it is automatically created as a side effect
+ * of calling this function, otherwise its last seen time is updated and
+ * the existing consumer reference returned. */
+streamConsumer *streamLookupConsumer(streamCG *cg, sds name) {
+    streamConsumer *c = raxFind(cg->consumers,(unsigned char*)name,
+                                sdslen(name));
+    if (c == raxNotFound) {
+        c = zmalloc(sizeof(*c));
+        c->name = sdsdup(name);
+        c->pel = raxNew();
+    }
+    c->seen_time = mstime();
+    return c;
+}
+
 /* -----------------------------------------------------------------------
  * Consumer groups commands
  * ----------------------------------------------------------------------- */