Streams: XLEN command.

src/server.c

@@ -304,6 +304,7 @@ struct redisCommand redisCommandTable[] = {
     {"pfdebug",pfdebugCommand,-3,"w",0,NULL,0,0,0,0,0},
     {"xadd",xaddCommand,-4,"wmF",0,NULL,1,1,1,0,0},
     {"xrange",xrangeCommand,-4,"r",0,NULL,1,1,1,0,0},
+    {"xlen",xlenCommand,2,"rF",0,NULL,1,1,1,0,0},
     {"post",securityWarningCommand,-1,"lt",0,NULL,0,0,0,0,0},
     {"host:",securityWarningCommand,-1,"lt",0,NULL,0,0,0,0,0},
     {"latency",latencyCommand,-2,"aslt",0,NULL,0,0,0,0,0}

src/server.h

@@ -2001,6 +2001,7 @@ void moduleCommand(client *c);
 void securityWarningCommand(client *c);
 void xaddCommand(client *c);
 void xrangeCommand(client *c);
+void xlenCommand(client *c);
 
 #if defined(__GNUC__)
 void *calloc(size_t count, size_t size) __attribute__ ((deprecated));

src/t_stream.c

@@ -378,3 +378,12 @@ void xrangeCommand(client *c) {
     s = o->ptr;
     streamReplyWithRange(c,s,&startid,&endid,count);
 }
+
+/* XLEN */
+void xlenCommand(client *c) {
+    robj *o;
+    if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL
+        || checkType(c,o,OBJ_STREAM)) return;
+    stream *s = o->ptr;
+    addReplyLongLong(c,s->length);
+}