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LenCachingMutex #9988
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LenCachingMutex #9988
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LenCachingMutex can be used in place of a Mutex, when working with collections, or other types with a len() method. When the Guard is dropped, the value returned from len() is stored into an AtomicUsize and can be queried using load_len() without needing to lock the Mutex.
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| self.len.load(Ordering::SeqCst) | ||
| } | ||
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| pub fn lock(&self) -> Guard<T> { |
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Please remember to add docs for public functions in the future!
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New util LenCachingMutex can be used in place of a Mutex, when working with collections, or other types with a len() method. When the Guard is dropped, the value returned from len() is stored into an AtomicUsize and can be queried using load_len() without needing to lock the Mutex. Implementations for ```Vec``` and ```VecDeque```. Now used in [Verification](https://github.com/paritytech/parity-ethereum/blob/4ded4181a651fe9c26850f908e4ab63bf952cab6/ethcore/src/verification/queue/mod.rs#L196) so that calls to ```VerificationQueue.queue_info()``` no longer require locks.
insipx
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New util LenCachingMutex can be used in place of a Mutex, when working with collections, or other types with a len() method. When the Guard is dropped, the value returned from len() is stored into an AtomicUsize and can be queried using load_len() without needing to lock the Mutex. Implementations for ```Vec``` and ```VecDeque```. Now used in [Verification](https://github.com/paritytech/parity-ethereum/blob/4ded4181a651fe9c26850f908e4ab63bf952cab6/ethcore/src/verification/queue/mod.rs#L196) so that calls to ```VerificationQueue.queue_info()``` no longer require locks.
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While working on another issue I developed a way to query the size of a collection held in a
Mutexwithout requiring a lock. Ultimately I found a a different way to solve the issue without needing this, but it may be useful anyway. I've included a commit to show it used inVerification. If another thread has the lock whileload_len()is called, the cached value may not be accurate. However this is often not too different to normal operation - stored len() may be stale at any point after the Guard is dropped.