[Bug] Reloading plugin creates duplicate event timers

[Dreae]

OS (windows, linux, ...): windows BeamMP-Server Version: master

Describe the bug Plugin auto-reloading on file changes does not clear timers created with CreateEventTimer causing duplicate timers to be created every time the plugin reloads. This also causes a crash if the event handler function changes name when the plugin reloads.

To Reproduce Steps to reproduce the behavior:

1. Create a timer using CreateEventTimer
2. Trigger a plugin reload by saving a file
3. The event function will be called twice per-period due to duplicate event timers

Expected behavior Reloading plugins clears existing event timers so they will be recreated cleanly when the plugin restarts

Logs

[26/11/23 12:30:51] main.cpp:196 [INFO] ALL SYSTEMS STARTED SUCCESSFULLY, EVERYTHING IS OKAY
[26/11/23 12:30:52] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:30:54] LuaAPI.cpp:105 [LUA] Hello there	
> status
BeamMP-Server Status:
	Total Players:             0
	Syncing Players:           0
	Synced Players:            0
	Connected Players:         0
	Guests:                    0
	Cars:                      0
	Uptime:                    10201ms (~0h) 
	Lua:
		Queued results to check:     0
		States:                      2
		Event timers:                1
		Event handlers:              1
	Subsystems:
		Good/Starting/Bad:           11/0/0
		Shutting down/Shut down:     0/0
		Good:                        [ Main, Server, Heartbeat, LuaEngine, Config, PPSMonitor, ResourceManager, UpdateCheck, PluginMonitor, TCPNetwork, UDPNetwork ]
		Starting:                    [  ]
		Bad:                         [  ]
		Shutting down:               [  ]
		Shut down:                   [  ]

[26/11/23 12:30:56] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:30:58] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:00] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:01] TPluginMonitor.cpp:41 [INFO] File "Resources\Server\TimerTest\main.lua" changed, reloading
[26/11/23 12:31:02] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:03] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:04] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:05] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:06] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:07] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:07] TPluginMonitor.cpp:41 [INFO] File "Resources\Server\TimerTest\main.lua" changed, reloading
[26/11/23 12:31:08] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:09] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:09] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:10] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:11] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:11] LuaAPI.cpp:105 [LUA] Hello there	
[26/11/23 12:31:12] LuaAPI.cpp:105 [LUA] Hello there	
> status
BeamMP-Server Status:
	Total Players:             0
	Syncing Players:           0
	Synced Players:            0
	Connected Players:         0
	Guests:                    0
	Cars:                      0
	Uptime:                    27491ms (~0h) 
	Lua:
		Queued results to check:     0
		States:                      2
		Event timers:                3
		Event handlers:              1
	Subsystems:
		Good/Starting/Bad:           11/0/0
		Shutting down/Shut down:     0/0
		Good:                        [ Main, Server, Heartbeat, LuaEngine, Config, PPSMonitor, ResourceManager, UpdateCheck, PluginMonitor, TCPNetwork, UDPNetwork ]
		Starting:                    [  ]
		Bad:                         [  ]
		Shutting down:               [  ]
		Shut down:                   [  ]

Additional Context Lua file used to reproduce the issue:

function SayHello()
    print("Hello there")
end

MP.RegisterEvent("TestTimer", "SayHello")
MP.CreateEventTimer("TestTimer", 2000)

[lionkor]

The way this currently is worked around is by always cancelling your event timers before starting them, much like unsubscribing event handlers in other languages before subscribing. Cancelling a nonexistent event timer is a no-op.

So, dirty fix:

  function SayHello()
      print("Hello there")
  end

  MP.RegisterEvent("TestTimer", "SayHello")
+ MP.CancelEventTimer("TestTimer")
  MP.CreateEventTimer("TestTimer", 2000)

Fixing this would require the following changes to be made to the lua/plugin engine:

• [ ] Keep track of which event handler and event timer comes from which file (currently they're just lua chunks I'm pretty sure)
• [ ] Cancel event timers that are started by a specific file when that file is reloaded

You could also potentially add an event for onBeforeReload or something, but nobody would end up using that IMO.