Question

How can I implement something like pthreads pthread_cond_signal on WinOS. I don’t want to use the pthreads Win32 port for this as I also support Win64.

I’m working on a task-based system where a client request spawns n-tasks that spawn n-threads on the server. After the client thread has spawned all the server tasks I want it to enter a sleep state or some other thread state that does not consume any system resources. When all the server tasks have completed I want the client thread to be awoken and return the result(s) to the client application.

Edit:
I’ve thought about waiting for a conditional variable in some shared memory, and check the condvar in a loop, but don’t loops consume resources too? I could add a sleep() inside the loop but then I won’t get the real-time client request & server response – as a task could take 1/1000 of a second (but also multiple seconds).

Answer 1

The Win32 API supports condition variables on Vista and higher. See this MSDN page for the API and this one for example usage.

WakeConditionVariable() is equivalent to pthread_cond_signal() and WakeAllConditionVariable() is equivalent to pthread_cond_broadcast()

That said, if you are on VS2012, I’d really recommend that you use the new C++11 threading library. It also has support for condition variables and since running on multiple platforms is important to you, using the standard library could help you eventually merge your codebases.