I am trying to use luasocket to connect to an Irc channel and send and receive messages within my game (Wolfenstein Enemy Territory, If that helps).
Right now I am able to do all of that, with one problem. Once I set it to listen for a message, it basically locks up. I have a fallback command if I type stoplisten in Irc it just stops the script, And I can see it got all the message, but the game itself is locked up while waiting for the messages.
Any Ideas on how I would do this without freezing the game? I have just recently learned a little of coroutines So I do not know if I am using them correctly.
I should also note I have access to a run frame functions which runs every millisecond if that helps (Though normally it is done like: if math.mod(currentTime, 50) ~= 0 then return end)
Here is the part in my code: http://pastebin.com/j1gCqm4R
(I wasnt gonna edit all my code with an indent just to post it here, so i just put it on pastebin)
Your problem is that all sockets are, by default, blocking, which means they will halt ('block') the current thread of execution (in this case, your game) until they either get the desired result or 'timeout'.
The solution is non-blocking sockets. invoke :settimeout(0) on your client socket object, and all future :send(...) :recieve(...) will return immediately, having either succeeded, or timed-out.
The LuaSocket reference contains the full details, but you will have to modify your code either to handle the 'timeout' failure state, or add calls to socket.select() to make sure that you only use sockets that are 'ready' to be used.
Related
Once in a game I was playing, a smart person wrote a cheat that allows you to disconnect all players from the server. I became interested in how it is possible to create protection against this. The situation was aggravated by the fact that the person who created the cheat distributed it to other players and disconnecting from the server became a regular event.
I got the source code of this cheat, I will show a fragment with a "connection switch":
I figured out how the cheat works. In the LLDB debugger, I found the Disconnect() function, it is called just when the "cheater" uses the cheat. In the disassembler, I decided to just remove Disconnect (), of course this is stupid, because I violated the logic of the game because of which I could not play. As a result of something, this function was called for me, I need to find out what code was executed before the breakpoint with Disconnect ()
Well its hard to tell, but my suggestion is you add some Debug.Log prints in certain scripts you think could be called before the disconnection happens, I know this sounds like a tedious work but you probably have some scripts you think could be called before. Else I would search for some keyword like "kickall" and be sure to set "all files in project" option so that it shows all possible candidates. I hope this serves you
For a game website, I want a player to contest either agains a human or an AI.
I am using Django + Channels (Django-4.0.2 asgiref-3.5.0 channels-3.0.4)
This is a long way of learning...
Human vs Human: the game take place is the web browser turn by turn. Each time a player connects, it opens a websocket connexion, a move is sent through the socket, processed by the consumer (validated and saved in the database) and sent to the other player.
It is managed only with sync programming.
Human vs AI: I try to use the same route as previously. A test branch check if the game is against the computer and process a move instead of receiving it from the other end of the websocket. This AI move can be a blocking operation as it can take from 2 to 5sec.
I don't want the receive method of the consumer to wait for the AI to return its move, since I have other operations to do quickly (like update some informations on the client side).
Then I thought I could easily take advantage of the allegedly already existing event loop of the channels framework. I could send the AI thinking process to this loop and return the result later to the client through the send method of the consumer.
However, when I write:
loop = asyncio.get_event_loop()
loop.create_task(my_AI_thinking())
Django raises a runtime effort error (the same as described here: https://github.com/django/asgiref/issues/278) telling me there is no running event loop.
The solution seemed to be to upgrade asgiref to 3.5.0 which I did but issue not solved.
I think I am a little bit short of background, and some enlightments should help me to understand a little bit more what is the root cause of this fail.
My first questions would be:
In the combo django + channels + asgi: which is in charge to run the eventloop?
How to check if indeed one event loop is running whatever the thread?
Maybe your answers wil raise other questions.
Did you try running your event_loop example on Django 3.2? (and/or with different Python version)? I experienced various problems with Django 4.0 & Python 3.10, so I keep with Django 3.2 and Python3.7/3.8/3.9 for now, maybe your errors are one of these problems?
If you won't be able to get event_loop running, I see two possible alternative solutions:
Open two WS connections: one only for the moves, and the other for all the other stuff, such as updating information on Player's UI, etc.
You can also use multiprocessing to "manually" send calculating AI move to other thread, and then join the two threads again, after receiving the result (the move). To be honest, multiprocessing in Python is quite simple -- it's pretty handy, if you are familiar with the idea of multithreaded applications.
Unfortunately, I have not yet used event loops in channels myself, maybe someone more experienced in that matter will be able to better address your issue.
I have an application which needs to run several other applications in chain. I am running them via ShellExecuteEx. The order of running each of the apps is very important cause they are dependant on each other. For example:
Start(App1);
If App1.IsRunning then
Start(App2);
If App2.IsRunning then
Start(App3);
.........................
If App(N-1).IsRunning then
Start(App(N));
Everything works fine but there is a one possible problem:
ShellExecuteEx starts the application, and return almost immediately. The problem might arise when for example App1 has started properly but has not finished some internal tasks, it is not yet ready to use. But ShellExecuteEx is already starting App2 which depends on the App1, and App2 won't start properly because it needs fully initialized App1.
Please note, that I don't want to wait for App(N-1) to finish and then start AppN.
I don't know if this is possible to solve with ShellExecuteEx, I've tried to use
SEInfo.fMask := SEE_MASK_NOCLOSEPROCESS or SEE_MASK_NOASYNC;
but without any effect.
After starting the AppN application I have a handle to the process. If I assume that the application is initialized after its main window is created (all of Apps have a window), can I somehow put a hook on its message queue and wait until WM_CREATE appears or maybe WM_ACTIVATE? In pressence of such message my Application would know that it can move on.
It's just an idea. However, I don't know how to put such hook. So if you could help me in this or you have a better idea that would be great:)
Also, the solution must work on Windows XP and above.
Thanks for your time.
Edited
#Cosmic Prund: I don't understand why did you delete your answer? I might try your idea...
You can probably achieve what you need by calling WaitForInputIdle() on each process handle returned by ShellExecute().
Waits until the specified process has finished processing its initial input and is waiting for user input with no input pending, or until the time-out interval has elapsed.
If your application has some custom initialization logic that doesn't run in UI thread then WaitForInputIdle might not help. In that case you need a mechanism to signal the previous app that you're done initializing.
For signaling you can use named pipes, sockets, some RPC mechanism or a simple file based lock.
You can always use IPC and Interpocess Synchronization to make your application communicate with (and wait for, if needed) each other, as long as you code both applications.
NOTE: I'll use the ssh_sftp channel as an example here, but I've noticed the same behaviour when using different channels.
After starting a channel:
{ok, ChannelPid} = ssh_sftp:start_channel(State#state.cm),
(where cm is my Connection Manager), I'm performing an operation through the channel. Say:
ssh_sftp:write_file(ChannelPid, FilePath, Content),
Then, I'm stopping the channel:
ssh_sftp:stop_channel(ChannelPid),
Since, as far as I know, the channel is implemented as a gen_server, I was expecting the requests to be sequentialized.
Well, after a bit of tracing, I've noticed that the channel is somehow stopped before the file write is completed and the result of the operation is sent through the channel. As a conclusion, the response is not sent through the channel, since the channel doesn't exist anymore.
If I don't stop the channel explicitely, everything works fine and the file write (or any other operation performed through the channel) is completed correctly. But I would prefer to avoid to leave open channels. On the other hand, I would prefer to avoid implementing my own receive handler to wait for the result before the channel can be stopped.
I'm probably missing something trivial here. Do you have any idea why this is happening and/or I could fix it?
I repeat, the ssh_sftp is just an example. I'm using my own channels, implemented using the existing channels in the Erlang SSH application as a template.
As you can see in ssh_sftp.erl it forcefully kills channel after 5 sec timeout with exit(Pid, kill) which interrupts the process regardless of whether it's processing something or not.
Related quote from erlang man:
If Reason is the atom kill, that is if exit(Pid, kill) is called, an untrappable exit signal is sent to Pid which will unconditionally exit with exit reason killed.
I had a similar issue with ssh_connection:exec/4. The problem is that these ssh sibling modules ( ssh_connection, ssh_sftp, etc) all appear to behave asynchronously, therefore a closure of channel of ssh itself will shut down the ongoing action.
The options are:
1) do not close the connection : this may lead to leak of resources. Purpose of my question here
2) After the sftp, introduce a monitoring function that waits by monitoring on the file you are transfering at the remote server ( checksum check ). This can be based on ssh_connection:exec and poll on the file you are transferring. Once the checksum matches what you expect, you can free the main module
I created a class that handles serial port asynchronously. I use it to communicate with a modem. I have no idea why, but sometimes, when I close my application, I get the Blue Screen and my computer restarts. I logged my code step by step, but when the BSOD appeared, and my computer restarted, the file into which I was logging data contained only white spaces. Therefore I have no idea, what the reason of the BSOD could be.
I looked through my code carefully and I found several possible reasons of the problem (I was looking for all that could lead to accessing unallocated memory and causing AV exceptions).
When I rethought the idea of asynchronous operations, a few things came to my mind. Please verify whether these are right:
1) WaitCommEvent() takes a pointer to the overlapped structure. Therefore, if I call WaitCommEvent() inside a function and then leave the function, the overlapped structure cannot be a local variable, right? The event mask variable and event handle too, right?
2) ReadFile() and WriteFile() also take references or pointers to variables. Therefore all these variables have to be accessible until the overlapped read or write operations finish, right?
3) I call WaitCommEvent() only once and check for its result in a loop, in the mean time doing other things. Because I have no idea how to terminate asynchronous operations (is it possible?), when I destroy my class that keeps a handle to a serial port, I first close the handle, and then wait for the event in the overlapped structure that was used when calling the WaitCommEvent() function. I do this to be sure that the thread that waits asynchronously for a comm event does not access any fields of my class which is destroyed. Is it a good idea or is it stupid?
try
CloseHandle(FSerialPortHandle);
if Assigned(FWaitCommEvent) then
FWaitCommEvent.WaitFor(INFINITE);
finally
FSerialPortHandle := INVALID_HANDLE_VALUE;
FreeAndNil(FWaitCommEvent);
end;
Before I noticed all these, most of the variables mentioned in point one and two were local variables of the functions that called the three methods above. Could it be the reason of the BSOD or should I look for some other mistakes in my code?
When I corrected the code, the BSOD stopped occuring, but It might be a coincidence. How do you think?
Any ideas will be appreciated. Thanks in advance.
I read the CancelIo() function documentation and it states that this method cancells all I/O operations issued by the calling thread. Is it OK to wait for the FWaitCommEvent after calling CancelIo() if I know that WaitCommEvent() was issued by a different thread than the one that calls CancelIo()?
if Assigned(FWaitCommEvent) and CancelIo(FSerialPortHandle) then
begin
FWaitCommEvent.WaitFor(INFINITE);
FreeAndNil(FWaitCommEvent);
end;
I checked what happens in such case and the thread calling this piece of code didn't get deadlocked even though it did not issue WaitCommEvent(). I tested in on Windows 7 (if it matters). May I leave the code as is or is it dangerous? Maybe I misunderstood the documentation and this is the reason of my question. I apologize for asking so many questions, but I really need to be sure about that.
Thanks.
An application running as a standard user should never be able to cause a bug check (a.k.a. BSOD). (And an application running as an Administrator should have to go well out of its way to do so.) Either you ran into a driver bug or you have bad hardware.
By default, Windows is configured to save a minidump in %SystemRoot%\minidump whenever a bug check occurs. You may be able to determine more information about the crash by loading the minidump file in WinDbg, configuring WinDbg to use the Microsoft public symbol store, and running the !analyze -v command in WinDbg. At the very least, this should identify what driver is probably at fault (though I would guess it's your modem driver).
Yes, you do need to keep the TOverlapped structure available for the duration of the overlapped operation. You're going to call GetOverlappedResult at some point, and GetOverlappedResult says it should receive a pointer to a structure that was used when starting the overlapped operation. The event mask and handle can be stored in local variables if you want; you're going to have a copy of them in the TOverlapped structure anyway.
Yes, the buffers that ReadFile and WriteFile use must remain valid. They do not make their own local copies to use internally. The documentation for ReadFile even says so:
This buffer must remain valid for the duration of the read operation. The caller must not use this buffer until the read operation is completed.
If you weren't obeying that rule, then you were likely reading into unreserved stack space, which could easily cause all sorts of unexpected behavior.
To cancel an overlapped I/O operation, use CancelIo. It's essential that you not free the memory of your TOverlapped record until you're sure the associated operation has terminated. Likewise for the buffer you're reading or writing. CancelIo does not cancel the operation immediately, so your buffers might still be in use even after you call it.