lockpool 3.0.1

This library offers a pool of locks where individual locks can be locked/unlocked by key
Documentation 
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/// [SyncLockPool] is an implementation of [LockPool] (see [LockPool] for API details) that is
/// based on [std::sync::Mutex] and can be used in synchronous code.
/// This implementation can also be used in `async` code and will be a little faster than [TokioLockPool],
/// but its locks cannot be held across `await` points if the corresponding async task is sent across threads.
///
/// [SyncLockPool] is based on top of [std::sync::Mutex] and supports poisoning of locks.
/// See the [std::sync::Mutex] documentation for details on poisoning.
pub type SyncLockPool<K> = super::LockPoolImpl<K, std::sync::Mutex<()>>;

#[cfg(test)]
mod tests {
    use super::SyncLockPool;
    use crate::pool::tests::utils::{
        launch_locking_owned_thread, launch_locking_thread, poison_lock, poison_lock_owned,
        poison_try_lock, poison_try_lock_owned,
    };
    use crate::{LockPool, PoisonError, TryLockError, UnpoisonError};
    use std::sync::atomic::{AtomicU32, Ordering};
    use std::sync::Arc;
    use std::thread;
    use std::time::Duration;

    crate::instantiate_common_tests!(common, super::SyncLockPool<isize>);

    fn assert_is_lock_poisoned_error<G>(expected_key: isize, error: &PoisonError<isize, G>) {
        assert_eq!(expected_key, error.key);
    }

    fn assert_is_try_lock_poisoned_error<G>(expected_key: isize, error: &TryLockError<isize, G>) {
        match error {
            TryLockError::Poisoned(PoisonError {
                key: actual_key, ..
            }) => {
                assert_eq!(expected_key, *actual_key);
            }
            _ => panic!("Wrong error type"),
        }
    }

    #[test]
    fn test_pool_mutex_poisoned_by_lock() {
        let pool = Arc::new(SyncLockPool::new());

        poison_lock(&pool, 3);

        // All future lock attempts should error
        {
            let err = pool.lock(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock_owned(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock_owned(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock_owned(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock_owned(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }
    }

    #[test]
    fn test_pool_mutex_poisoned_by_lock_owned() {
        let pool = Arc::new(SyncLockPool::new());

        poison_lock_owned(&pool, 3);

        // All future lock attempts should error
        {
            let err = pool.lock(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock_owned(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock_owned(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock_owned(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock_owned(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }
    }

    #[test]
    fn test_pool_mutex_poisoned_by_try_lock() {
        let pool = Arc::new(SyncLockPool::new());

        poison_try_lock(&pool, 3);

        // All future lock attempts should error
        {
            let err = pool.lock(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock_owned(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock_owned(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock_owned(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock_owned(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }
    }

    #[test]
    fn test_pool_mutex_poisoned_by_try_lock_owned() {
        let pool = Arc::new(SyncLockPool::new());

        poison_try_lock_owned(&pool, 3);

        // All future lock attempts should error
        {
            let err = pool.lock(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock_owned(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock_owned(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.lock_owned(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }

        {
            let err = pool.try_lock_owned(3).unwrap_err();
            assert_is_try_lock_poisoned_error(3, &err);
        }
    }

    #[test]
    fn test_poison_error_holds_lock() {
        let pool = Arc::new(SyncLockPool::new());
        poison_lock(&pool, 5);
        let error = pool.lock(5).unwrap_err();
        assert_is_lock_poisoned_error(5, &error);

        let counter = Arc::new(AtomicU32::new(0));

        let child = launch_locking_thread(&pool, 5, &counter, None);

        // Check that even if we wait, the child thread won't get the lock
        thread::sleep(Duration::from_millis(100));
        assert_eq!(0, counter.load(Ordering::SeqCst));

        // Now free the lock so the child can get it
        std::mem::drop(error);

        // And check that the child got it
        child.join().unwrap_err();
        assert_eq!(1, counter.load(Ordering::SeqCst));

        // The poisoned lock is still there
        assert_eq!(1, pool.num_locked_or_poisoned());
    }

    #[test]
    fn test_poison_error_holds_lock_owned() {
        let pool = Arc::new(SyncLockPool::new());
        poison_lock_owned(&pool, 5);
        let error = pool.lock_owned(5).unwrap_err();
        assert_is_lock_poisoned_error(5, &error);

        let counter = Arc::new(AtomicU32::new(0));

        let child = launch_locking_owned_thread(&pool, 5, &counter, None);

        // Check that even if we wait, the child thread won't get the lock
        thread::sleep(Duration::from_millis(100));
        assert_eq!(0, counter.load(Ordering::SeqCst));

        // Now free the lock so the child can get it
        std::mem::drop(error);

        // And check that the child got it
        child.join().unwrap_err();
        assert_eq!(1, counter.load(Ordering::SeqCst));

        // The poisoned lock is still there
        assert_eq!(1, pool.num_locked_or_poisoned());
    }

    #[test]
    fn test_poison_error_holds_try_lock() {
        let pool = Arc::new(SyncLockPool::new());
        poison_lock(&pool, 5);
        let error = pool.lock(5).unwrap_err();
        assert_is_lock_poisoned_error(5, &error);

        let err = pool.try_lock(5).unwrap_err();
        assert!(matches!(err, TryLockError::WouldBlock));

        // Now free the lock so the child can get it
        std::mem::drop(error);

        // And check that it is still poisoned
        let err = pool.try_lock(5).unwrap_err();
        assert_is_try_lock_poisoned_error(5, &err);

        // The poisoned lock is still there
        assert_eq!(1, pool.num_locked_or_poisoned());
    }

    #[test]
    fn test_poison_error_holds_try_lock_owned() {
        let pool = Arc::new(SyncLockPool::new());
        poison_lock_owned(&pool, 5);
        let error = pool.lock_owned(5).unwrap_err();
        assert_is_lock_poisoned_error(5, &error);

        let err = pool.try_lock_owned(5).unwrap_err();
        assert!(matches!(err, TryLockError::WouldBlock));

        // Now free the lock so the child can get it
        std::mem::drop(error);

        // And check that it is still poisoned
        let err = pool.try_lock(5).unwrap_err();
        assert_is_try_lock_poisoned_error(5, &err);

        // The poisoned lock is still there
        assert_eq!(1, pool.num_locked_or_poisoned());
    }

    #[test]
    fn test_unpoison() {
        let pool = Arc::new(SyncLockPool::new());

        poison_lock(&pool, 3);

        // Check that it is actually poisoned
        {
            let err = pool.lock(3).unwrap_err();
            assert_is_lock_poisoned_error(3, &err);
        }

        pool.unpoison(3).unwrap();

        // Check that it got unpoisoned
        {
            let _g = pool.lock(3).unwrap();
        }
        {
            let _g = pool.lock_owned(3).unwrap();
        }
        {
            let _g = pool.try_lock(3).unwrap();
        }
        {
            let _g = pool.try_lock_owned(3).unwrap();
        }
    }

    #[test]
    fn test_unpoison_not_poisoned() {
        let pool = Arc::new(SyncLockPool::new());

        let err = pool.unpoison(3).unwrap_err();
        assert_eq!(UnpoisonError::NotPoisoned, err);
    }

    #[test]
    fn test_unpoison_while_other_thread_waiting() {
        let pool = Arc::new(SyncLockPool::new());

        poison_lock(&pool, 3);

        let _err_guard = pool.lock(3).unwrap_err();

        // _err_guard keeps it locked

        let err = pool.unpoison(3).unwrap_err();
        assert!(matches!(err, UnpoisonError::OtherThreadsBlockedOnMutex));
    }
}