Blocking/Non-blocking vs Sync/Async

When an I/O function is invoked:

• Blocking: Waits for the process to complete before returning.
• Non-Blocking: Returns immediately, regardless of whether the task has finished.

In terms of who oversees task completion for the I/O function:

• Synchronous: Managed by the application.
• Asynchronous: Overseen by the kernel.

epoll vs kqueque

Kqueue allows one to batch modify watcher states and to retrieve watcher states in a single system call. With epoll, you have to call a system call for every modification. Kqueue also allows one to watch for things like filesystem changes and process state changes, epoll is limited to socket/pipe I/O only.

Reactor pattern

didawiki.cli.di.unipi.it/lib/exe/fet…

The Reactor pattern allows event-driven applications to demultiplex and dispatch synchronously and serially service requests that are received simultaneously from one or more clients.

• It waits for indication events to occur on some event sources.

• Indication event: event that identify the arrival of a request.

• Non-blocking Synchronous I/O strategy

• the control is returned to the caller immediately: the call was performed and the results are ready, or the system has no resources to execute the requested operation.

Proactor pattern

The Proactor pattern allows event-driven applications to demultiplex and dispatch service requests in an efficient asynchronous way.

. It waits for completion events to occur on some event sources.

• Completion event: event that identify the end of the execution of an asynchronous operation.

• Non-blocking Asynchronous I/O strategy

• the control is returned to the caller immediately, indicating that the requested operation was initiated. The called system will notify the caller.