Added constraints to mimick real API behavior

lib/MockMessagingService/init.lua

@@ -1,16 +1,5 @@
 local MockMessagingService = {}
 
---[[ TODO constraints:
-
- [Limit] [Maximum]
- Size of message 1kB
- Messages sent per game server 150 + 60 * (number of players in this game server) per minute
- Messages received per topic (10 + 20 * number of servers) per minute
- Messages received for entire game (100 + 50 * number of servers) per minute
- Subscriptions allowed per game server 5 + 2 * (number of players in this game server)
-
---]]
-
 local function _getOrNew(name)
  local rq = script:FindFirstChild(name, false)
 

plugin/init.server.lua

@@ -4,18 +4,18 @@ if not plugin then return end
 local toolbar = plugin:CreateToolbar("MockMessagingService plugin")
 local enabled = false
 
-function _clone()
- _remove()
- local clone = script.Parent.MessagingService.MockMessagingService:Clone()
- clone.Parent = game.ServerScriptService.MessagingService
-end
-
-function _remove()
+local function _remove()
  if game.ServerScriptService.MessagingService:FindFirstChild("MockMessagingService") ~= nil then
  game.ServerScriptService.MessagingService.MockMessagingService:Destroy()
  end
 end
 
+local function _clone()
+ _remove()
+ local clone = script.Parent.MessagingService.MockMessagingService:Clone()
+ clone.Parent = game.ServerScriptService.MessagingService
+end
+
 -- TODO: proper icon
 local toggleButton = toolbar:CreateButton("Toggle MMS", "Enables or disables MockMessagingService", "rbxassetid://484838285")
 toggleButton.ClickableWhenViewportHidden = true
@@ -36,11 +36,6 @@ end
 
 toggleButton.Click:Connect(toggleButtonClicked)
 
-plugin.Unloading:Connect(function()
- enabled = false
- _remove()
-end)
-
 -- ################## Data exchange logic ##################
 local MMS = game.ServerScriptService:WaitForChild("MessagingService"):WaitForChild("MockMessagingService")
 
@@ -49,25 +44,114 @@ local subscribeRequest: BindableEvent = MMS:WaitForChild("SubscribeRequest")
 
 local subscribedTopics = {}
 
+local function _elapsedSeconds(lastTime)
+ local currentTimestamp = os.time()
+ return currentTimestamp - lastTime
+end
+
+local function _serverCount()
+ return plugin:GetSetting("_serverCount") or 0
+end
+
+-- increase the number of servers currently using MMS by one
+plugin:SetSetting("_serverCount", _serverCount() + 1)
+
+--[[ Constraints:
+
+ [Limit] [Maximum]
+ Size of message 1kB
+ Messages sent per game server 150 + 60 * (number of players in this game server) per minute
+ Messages received per topic (10 + 20 * number of servers) per minute
+ Messages received for entire game (100 + 50 * number of servers) per minute
+ Subscriptions allowed per game server 5 + 2 * (number of players in this game server)
+
+--]]
+local Constraints = {
+ sentMessages = {
+ max = (150 + 60 * #game.Players:GetPlayers()) / 60,
+ count = 0,
+ lastTime = os.time()
+ },
+ subscriptions = {
+ max = 5 + 2 * #game.Players:GetPlayers(),
+ count = 0
+ },
+ receivedMessagesTopic = {
+ max = (10 + 20 * _serverCount()) / 60,
+ count = 0,
+ lastTime = os.time()
+ },
+ receivedMessagesTotal = {
+ max = (100 + 50 * _serverCount()) / 60,
+ count = 0,
+ lastTime = os.time()
+ }
+}
+
 publishRequest.Event:Connect(function (topic: string, message)
+ -- check if message size exceeds 1kB
+ if string.len(tostring(message)) > 1024 then
+ error("Message size exceeds 1kB")
+ end
+
+ -- check if message limit per game server is reached
+ Constraints.sentMessages.count += 1
+ local elapsed = _elapsedSeconds(Constraints.sentMessages.lastTime)
+ if Constraints.sentMessages.count > Constraints.sentMessages.max * elapsed then
+ error("Message limit per game server per minute reached")
+ end
+
  -- plugin:SetSetting hits disc instead of memory, so it can be slow. Spawn so we don't hang.
  task.spawn(plugin.SetSetting, plugin, topic, message)
+
+ Constraints.lastTimestamp = os.time()
 end)
 
 subscribeRequest.Event:Connect(function (topic: string)
+ -- check if already subscribed to topic
+ if subscribedTopics[topic] ~= nil then return end
+
+ -- check if subscription limit per game server is reached
+ Constraints.subscriptions.count += 1
+ if Constraints.subscriptions.count >= Constraints.subscriptions.max then
+ error("Subscription limit per game server reached")
+ end
+
  table.insert(subscribedTopics, topic)
+
+ Constraints.lastTimestamp = os.time()
 end)
 
 game:GetService("RunService").Heartbeat:Connect(function()
+ -- Check if message limit for entire game is reached
+ local elapsed = _elapsedSeconds(Constraints.receivedMessagesTotal.lastTime)
+ if Constraints.receivedMessagesTotal.count >= Constraints.receivedMessagesTotal.max * elapsed then
+ return
+ end
+
  for i, topic in ipairs(subscribedTopics) do
+ -- check if message limit per topic is reached
+ local elapsed = _elapsedSeconds(Constraints.receivedMessagesTopic.lastTime)
+ if Constraints.receivedMessagesTopic.count >= Constraints.receivedMessagesTopic.max * elapsed then
+ continue
+ end
+
  local data = plugin:GetSetting(topic)
  if data then
  -- we want to clear the setting field even if there's
  -- no one subscribed to this topic ready to accept the data
- plugin:SetSetting(topic, nil)
+ task.spawn(plugin.SetSetting, plugin, topic, nil)
 
  local callback: BindableEvent = MMS:WaitForChild(topic .. "_CallbackEvent")
  callback:Fire(data)
  end
  end
+end)
+
+-- Unloading
+plugin.Unloading:Connect(function()
+ plugin:SetSetting("_serverCount", _serverCount() - 1)
+
+ enabled = false
+ _remove()
 end)