concurrent cluster link, fix issue #757

service/clusterd.lua

@@ -14,7 +14,18 @@ local function read_response(sock)
 	return cluster.unpackresponse(msg)	-- session, ok, data, padding
 end
 
+local connecting = {}
+
 local function open_channel(t, key)
+	local ct = connecting[key]
+	if ct then
+		local co = coroutine.running()
+		table.insert(ct, co)
+		skynet.wait(co)
+		return assert(ct.channel)
+	end
+	ct = {}
+	connecting[key] = ct
 	local host, port = string.match(node_address[key], "([^:]+):(.*)$")
 	local c = sc.channel {
 		host = host,
@@ -22,8 +33,16 @@ local function open_channel(t, key)
 		response = read_response,
 		nodelay = true,
 	}
-	assert(c:connect(true))
-	t[key] = c
+	local succ, err = pcall(c.connect, c, true)
+	if succ then
+		t[key] = c
+		ct.channel = c
+	end
+	connecting[key] = nil
+	for _, co in ipairs(ct) do
+		skynet.wakeup(co)
+	end
+	assert(succ, err)
 	return c
 end