#pragma once
#include "../C/Baselib_ReentrantLock.h"
#include "Time.h"
namespace baselib
{
BASELIB_CPP_INTERFACE
{
// In computer science, the reentrant mutex (recursive mutex, recursive lock) is particular type of mutual exclusion (mutex) device that may be locked multiple
// times by the same process/thread, without causing a deadlock.
// While any attempt to perform the "lock" operation on an ordinary mutex (lock) would either fail or block when the mutex is already locked, on a recursive
// mutex this operation will succeed if and only if the locking thread is the one that already holds the lock. Typically, a recursive mutex tracks the number
// of times it has been locked, and requires equally many unlock operations to be performed before other threads may lock it.
//
// "Reentrant mutex", Wikipedia: The Free Encyclopedia
// https://en.wikipedia.org/w/index.php?title=Reentrant_mutex&oldid=818566928
//
// For optimal performance, baselib::ReentrantLock should be stored at a cache aligned memory location.
class ReentrantLock
{
public:
// non-copyable
ReentrantLock(const ReentrantLock& other) = delete;
ReentrantLock& operator=(const ReentrantLock& other) = delete;
// non-movable (strictly speaking not needed but listed to signal intent)
ReentrantLock(ReentrantLock&& other) = delete;
ReentrantLock& operator=(ReentrantLock&& other) = delete;
// Creates a reentrant lock synchronization primitive.
// If there are not enough system resources to create a lock, process abort is triggered.
ReentrantLock() : m_ReentrantLockData(Baselib_ReentrantLock_Create())
{
}
// Reclaim resources and memory held by lock.
//
// If threads are waiting on the lock, calling free may trigger an assert and may cause process abort.
// Calling this function with a nullptr result in a no-op
~ReentrantLock()
{
Baselib_ReentrantLock_Free(&m_ReentrantLockData);
}
// Acquire lock.
//
// If lock is already acquired by the current thread this function increase the lock count so that an equal number of calls to Baselib_ReentrantLock_Release needs
// to be made before the lock is released.
// If lock is held by another thread, this function wait for lock to be released.
//
// This function is guaranteed to emit an acquire barrier.
inline void Acquire()
{
return Baselib_ReentrantLock_Acquire(&m_ReentrantLockData);
}
// Try to acquire lock and return immediately.
// If lock is already acquired by the current thread this function increase the lock count so that an equal number of calls to Baselib_ReentrantLock_Release needs
// to be made before the lock is released.
//
// When lock is acquired this function is guaranteed to emit an acquire barrier.
//
// Return: true if lock was acquired.
COMPILER_WARN_UNUSED_RESULT
FORCE_INLINE bool TryAcquire()
{
return Baselib_ReentrantLock_TryAcquire(&m_ReentrantLockData);
}
// Try to acquire lock.
// If lock is already acquired by the current thread this function increase the lock count so that an equal number of calls to Baselib_ReentrantLock_Release needs
// to be made before the lock is released.
// If lock is held by another thread, this function wait for timeoutInMilliseconds for lock to be released.
//
// When lock is acquired this function is guaranteed to emit an acquire barrier.
//
// TryAcquire with a zero timeout differs from TryAcquire() in that TryAcquire() is guaranteed to be a user space operation
// while TryAcquire with zero timeout may enter the kernel and cause a context switch.
//
// Timeout passed to this function may be subject to system clock resolution.
// If the system clock has a resolution of e.g. 16ms that means this function may exit with a timeout error 16ms earlier than originally scheduled.
//
// Return: true if lock was acquired.
COMPILER_WARN_UNUSED_RESULT
FORCE_INLINE bool TryTimedAcquire(const timeout_ms timeoutInMilliseconds)
{
return Baselib_ReentrantLock_TryTimedAcquire(&m_ReentrantLockData, timeoutInMilliseconds.count());
}
// Release lock.
// If lock count is still higher than zero after the release operation then lock remain in a locked state.
// If lock count reach zero the lock is unlocked and made available to other threads
//
// When the lock is released this function is guaranteed to emit a release barrier.
//
// Calling this function from a thread that doesn't own the lock triggers an assert in debug and causes undefined behavior in release builds.
FORCE_INLINE void Release()
{
return Baselib_ReentrantLock_Release(&m_ReentrantLockData);
}
// Acquire lock and invoke user defined function.
// If lock is held by another thread, this function wait for lock to be released.
//
// When a lock is acquired this function is guaranteed to emit an acquire barrier.
//
// Example usage:
// lock.AcquireScoped([] {
// enteredCriticalSection++;
// });
template<class FunctionType>
FORCE_INLINE void AcquireScoped(const FunctionType& func)
{
ReleaseOnDestroy releaseScope(*this);
Acquire();
func();
}
// Try to acquire lock and invoke user defined function.
// If lock is held by another thread, this function wait for timeoutInMilliseconds for lock to be released.
// On failure to obtain lock the user defined function is not invoked.
//
// When lock is acquired this function is guaranteed to emit an acquire barrier.
//
// Example usage:
// lock.TryAcquireScoped([] {
// enteredCriticalSection++;
// });
//
// Return: true if lock was acquired.
template<class FunctionType>
FORCE_INLINE bool TryAcquireScoped(const FunctionType& func)
{
if (TryAcquire())
{
ReleaseOnDestroy releaseScope(*this);
func();
return true;
}
return false;
}
// Try to acquire lock and invoke user defined function.
// If lock is held by another thread, this function wait for timeoutInMilliseconds for lock to be released.
// On failure to obtain lock the user defined function is not invoked.
//
// When lock is acquired this function is guaranteed to emit an acquire barrier.
//
// Timeout passed to this function may be subject to system clock resolution.
// If the system clock has a resolution of e.g. 16ms that means this function may exit with a timeout error 16ms earlier than originally scheduled.
//
// Example usage:
// bool lockAcquired = lock.TryTimedAcquireScoped(std::chrono::minutes(1), [] {
// enteredCriticalSection++;
// });
// assert(lockAcquired);
//
// Return: true if lock was acquired.
template<class FunctionType>
FORCE_INLINE bool TryTimedAcquireScoped(const timeout_ms timeoutInMilliseconds, const FunctionType& func)
{
if (TryTimedAcquire(timeoutInMilliseconds))
{
ReleaseOnDestroy releaseScope(*this);
func();
return true;
}
return false;
}
private:
class ReleaseOnDestroy
{
public:
FORCE_INLINE ReleaseOnDestroy(ReentrantLock& lockReference) : m_LockReference(lockReference) {}
FORCE_INLINE ~ReleaseOnDestroy() { m_LockReference.Release(); }
private:
ReentrantLock& m_LockReference;
};
Baselib_ReentrantLock m_ReentrantLockData;
};
}
}