PriorityQueue - Rust #004 - Blocking Dequeue

This video is in French.

In this video, we continue building our concurrent Priority Queue. This time we add a blocking version of the dequeue() method and handle controlled shutdown with shutdown_immediate().

Topics covered

• Why try_dequeue() is not sufficient (the polling problem)
• Designing a blocking dequeue() method with Condvar
• The wait predicate (!pq.is_empty()) || closed
• Handling spurious wakeups
• The mutation-then-notification order for safe behavior
• Implementing a clean and consistent immediate shutdown (shutdown_immediate)

An important step before introducing graceful shutdowns and timeouts in the next video.

Useful links

• std::sync::Condvar
• Spurious wakeups
• Mutex
• Arc

Source code: github.com/xigh/pq-async-rs