[−][src]Crate semka

Semaphore primitive for Rust

Types

Library supplied two types of semaphores, which generally should not be mixed together as it created a mess.

Binary

Binary semaphore is similar to the Mutex as it allows singular lock & unlock.

This is the approach that should work for most simple use cases.

This implementation is available for all targets.

 use semka::{Sem, BinarySemaphore};
 let sem = Sem::new().unwrap();

 let _guard = sem.lock();

Counting Semaphore

Semaphore state is expressed as atomic integer, which gets decremented(if possible) on wait If decrement is not possible (i.e. state is 0) then it awaits for state to get incremented.

Meanwhile signal increments the counter. If any other tried is locked in wait, then it also wakes one of the locked threads.

 use semka::{Sem, CountingSemaphore};
 let sem = Sem::new(0).unwrap();

 assert!(sem.try_lock().is_none());
 sem.signal();
 sem.signal();
 let _guard = sem.lock();
 assert!(sem.try_wait());
 assert!(!sem.try_wait());

 drop(_guard);
 assert!(sem.try_wait());