libcryfs/lock/LockPool.h

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#pragma once
#ifndef MESSMER_CPPUTILS_LOCK_LOCKPOOL_H
#define MESSMER_CPPUTILS_LOCK_LOCKPOOL_H
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#include <mutex>
#include <condition_variable>
#include <vector>
#include <algorithm>
#include "../assert/assert.h"
#include "../macros.h"
//TODO Test
//TODO Rename package to synchronization
//TODO Rename to MutexPool
namespace cpputils {
template<class LockName>
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class LockPool final {
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public:
LockPool();
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~LockPool();
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void lock(const LockName &lock, std::unique_lock<std::mutex> *lockToFreeWhileWaiting = nullptr);
void release(const LockName &lock);
private:
bool _isLocked(const LockName &lock) const;
std::vector<LockName> _lockedLocks;
std::mutex _mutex;
std::condition_variable _cv;
DISALLOW_COPY_AND_ASSIGN(LockPool);
};
template<class LockName>
inline LockPool<LockName>::LockPool(): _lockedLocks(), _mutex(), _cv() {}
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template<class LockName>
inline LockPool<LockName>::~LockPool() {
ASSERT(_lockedLocks.size() == 0, "Still locks open");
}
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template<class LockName>
inline void LockPool<LockName>::lock(const LockName &lock, std::unique_lock<std::mutex> *lockToFreeWhileWaiting) {
std::unique_lock<std::mutex> mutexLock(_mutex); // TODO Is shared_lock enough here?
if (_isLocked(lock)) {
if(lockToFreeWhileWaiting != nullptr) {
lockToFreeWhileWaiting->unlock();
}
_cv.wait(mutexLock, [this, &lock]{
return !_isLocked(lock);
});
if(lockToFreeWhileWaiting != nullptr) {
lockToFreeWhileWaiting->lock();
}
}
_lockedLocks.push_back(lock);
}
template<class LockName>
inline bool LockPool<LockName>::_isLocked(const LockName &lock) const {
return std::find(_lockedLocks.begin(), _lockedLocks.end(), lock) != _lockedLocks.end();
}
template<class LockName>
inline void LockPool<LockName>::release(const LockName &lock) {
std::unique_lock<std::mutex> mutexLock(_mutex);
auto found = std::find(_lockedLocks.begin(), _lockedLocks.end(), lock);
ASSERT(found != _lockedLocks.end(), "Lock given to release() was not locked");
_lockedLocks.erase(found);
_cv.notify_all();
}
}
#endif