change multicast api

service/multicastd.lua

@@ -9,6 +9,7 @@ local channel = {}
 local channel_n = {}
 local channel_remote = {}
 local channel_id = harbor_id
+local NORET = {}
 
 local function get_address(t, id)
 	local v = assert(datacenter.get("multicast", id))
@@ -18,20 +19,58 @@ end
 
 local node_address = setmetatable({}, { __index = get_address })
 
+-- new LOCAL channel , The low 8bit is the same with harbor_id
 function command.NEW()
+	while channel[channel_id] do
+		channel_id = mc.nextid(channel_id)
+	end
 	channel[channel_id] = {}
 	channel_n[channel_id] = 0
 	local ret = channel_id
-	channel_id = channel_id + 256
+	channel_id = mc.nextid(channel_id)
 	return ret
 end
 
+-- MUST call by the owner node of channel, delete a remote channel
+function command.DELR(source, c)
+	channel[c] = nil
+	channel_n[c] = nil
+	return NORET
+end
+
+-- delete a channel, if the channel is remote, forward the command to the owner node
+-- otherwise, delete the channel, and call all the remote node, DELR
+function command.DEL(source, c)
+	local node = c % 256
+	if node ~= harbor_id then
+		skynet.send(node_address[node], "lua", "DEL", c)
+		return NORET
+	end
+	local remote = channel_remote[c]
+	channel[c] = nil
+	channel_n[c] = nil
+	channel_remote[c] = nil
+	for node in pairs(remote) do
+		skynet.send(node_address[node], "lua", "DELR", c)
+	end
+	return NORET
+end
+
+-- forward multicast message to a node (channel id use the session field)
 local function remote_publish(node, channel, source, ...)
 	skynet.redirect(node_address[node], source, "multicast", channel, ...)
 end
 
+-- publish a message, for local node, use the message pointer (call mc.bind to add the reference)
+-- for remote node, call remote_publish. (call mc.unpack and skynet.tostring to convert message pointer to string)
 local function publish(c , source, pack, size)
-	local group = assert(channel[c])
+	local group = channel[c]
+	if group == nil then
+		-- dead channel, delete the pack
+		mc.bind(pack, 1)
+		mc.close(pack)
+		return
+	end
 	mc.bind(pack, channel_n[c])
 	local msg = skynet.tostring(pack, size)
 	for k in pairs(group) do
@@ -56,6 +95,8 @@ skynet.register_protocol {
 	dispatch = publish,
 }
 
+-- publish a message, if the caller is remote, forward the message to the owner node (by remote_publish)
+-- If the caller is local, call publish
 function command.PUB(source, c, pack, size)
 	assert(skynet.harbor(source) == harbor_id)
 	local node = c % 256
@@ -67,9 +108,17 @@ function command.PUB(source, c, pack, size)
 	end
 end
 
+-- the node (source) subscribe a channel
+-- MUST call by channel owner node (assert source is not local and channel is create by self)
+-- If channel is not exist, return true
+-- Else set channel_remote[channel] true
 function command.SUBR(source, c)
 	local node = skynet.harbor(source)
-	assert(node ~= harbor_id)
+	if not channel[c] then
+		-- channel none exist
+		return true
+	end
+	assert(node ~= harbor_id and c % 256 == harbor_id)
 	local group = channel_remote[c]
 	if group == nil then
 		group = {}
@@ -78,30 +127,37 @@ function command.SUBR(source, c)
 	group[node] = true
 end
 
+-- the service (source) subscribe a channel
+-- If the channel is remote, node subscribe it by send a SUBR to the owner .
 function command.SUB(source, c)
 	local node = c % 256
 	if node ~= harbor_id then
 		-- remote group
 		if channel[c] == nil then
+			if skynet.call(node_address[node], "lua", "SUBR", c) then
+				return
+			end
 			channel[c] = {}
 			channel_n[c] = 0
-			skynet.call(node_address[node], "lua", "SUBR", c)
 		end
 	end
-	local group = assert(channel[c])
-	if not group[source] then
+	local group = channel[c]
+	if group and not group[source] then
 		channel_n[c] = channel_n[c] + 1
 		group[source] = true
 	end
 end
 
+-- MUST call by a node, unsubscribe a channel
 function command.USUBR(source, c)
 	local node = skynet.harbor(source)
 	assert(node ~= harbor_id)
 	local group = assert(channel_remote[c])
 	group[node] = nil
+	return NORET
 end
 
+-- Unsubscribe a channel, if the subscriber is empty and the channel is remote, send USUBR to the channel owner
 function command.USUB(source, c)
 	local group = assert(channel[c])
 	if group[source] then
@@ -113,16 +169,20 @@ function command.USUB(source, c)
 				-- remote group
 				channel[c] = nil
 				channel_n[c] = nil
-				skynet.call(node_address[node], "lua", "USUBR", c)
+				skynet.send(node_address[node], "lua", "USUBR", c)
 			end
 		end
 	end
+	return NORET
 end
 
 skynet.start(function()
 	skynet.dispatch("lua", function(_,source, cmd, ...)
 		local f = assert(command[cmd])
-		skynet.ret(skynet.pack(f(source, ...)))
+		local result = f(source, ...)
+		if result ~= NORET then
+			skynet.ret(skynet.pack(result))
+		end
 	end)
 	local self = skynet.self()
 	local id = skynet.harbor(self)