C++ WxWidgets: Single log window for messages from Multiple Threads

Question

What's the best/proper method to collect log messages from multiple threads and have them all be displayed using a window? (while the threads are running).

I am currently trying to redirect stdout (cout) in to a wxTextCtrl but failing miserably when attempting to do so over multiple threads. Any help would be appreciated.

Answer 1

In what way is it failing? I'm not familiar with the wxTextCtrl, but unless it has built in synchronization (ie. its thread safe) that could be a big issue. The simplest way to protect a single resource like this is via a named 'mutex'. The following example is what you can do in each thread to make sure that only one accesses this resource (the output window) at a time.

// In each thread's initialization:
HANDLE mutexHandle = CreateMutex(0,FALSE,"__my_protecting_mutex__");


// Whenever you use the debug output:

WaitForSingleObject(mutexHandle, /* Timeout if you like. */ 0xFFFFFFFF );
// Do our printing here.
ReleaseMutex(mutexHandle);


// In each thread's cleanup:
CloseHandle(mutexHandle);

So this basically guarantees that only one thread can be in between the wait and the release. Now if your issue is actually routing to the wxTextCtrl, I would need some more details.

Edit: I just realized that what I posted is Windows specific, and maybe you aren't on windows! If you aren't I don't have experience with other platform's synchronization methods, but boost has some generic libraries which are not platform specific.

Answer 2

Logging has had a few major updates recently in the wxWidgets trunk, you can read about them here. One of them is to add support for logging from threads other than the main thread.