Linux, C++, Waiting for an event using poll/select ( w/o blocking the executing thread )

Question

Use-case

• Single threaded Application
• Non-blocking Async-IO using poll
• A waitable object ( eg. a mutex ) with a timeout period

Problem at hand

I don;t want to create a specialized thread to wait for a timeout, and thus, I want to use poll to wait for a timeout on the waitable object in an ~Async~ fashion.

Is it possible to get notified for a mutex wait timeout using poll?

Main thread Pseudo code

• Existing logic
  1. wait for multiple FDs using poll
  2. for each ~ready~ FD, process the IO
  3. goto #1
• Desired Logic
  1. wait for multiple FDs and Mutexes using poll
  2. for each ~ready~ FD, process the IO
  3. For each timedout mutex process timeout ( eg. execute a registered callback )
  4. For each signaled mutex process wait completion
  5. goto #1

Answer 1

Pthread mutexes do not have a file handle.

Implement your own mutex on top of eventfd, then you can wait for it with poll().