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/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2022 - Raw Material Software Limited
JUCE is an open source library subject to commercial or open-source
licensing.
The code included in this file is provided under the terms of the ISC license
http://www.isc.org/downloads/software-support-policy/isc-license. Permission
To use, copy, modify, and/or distribute this software for any purpose with or
without fee is hereby granted provided that the above copyright notice and
this permission notice appear in all copies.
JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
DISCLAIMED.
==============================================================================
*/
namespace juce
{
//==============================================================================
/**
A simple spin-lock class that can be used as a simple, low-overhead mutex for
uncontended situations.
Note that unlike a CriticalSection, this type of lock is not re-entrant, and may
be less efficient when used in a highly contended situation, but it's very small and
requires almost no initialisation.
It's most appropriate for simple situations where you're only going to hold the
lock for a very brief time.
@see CriticalSection
@tags{Core}
*/
class JUCE_API SpinLock
{
public:
inline SpinLock() = default;
inline ~SpinLock() = default;
/** Acquires the lock.
This will block until the lock has been successfully acquired by this thread.
Note that a SpinLock is NOT re-entrant, and is not smart enough to know whether the
caller thread already has the lock - so if a thread tries to acquire a lock that it
already holds, this method will never return!
It's strongly recommended that you never call this method directly - instead use the
ScopedLockType class to manage the locking using an RAII pattern instead.
*/
void enter() const noexcept;
/** Attempts to acquire the lock, returning true if this was successful. */
inline bool tryEnter() const noexcept
{
return lock.compareAndSetBool (1, 0);
}
/** Releases the lock. */
inline void exit() const noexcept
{
jassert (lock.get() == 1); // Agh! Releasing a lock that isn't currently held!
lock = 0;
}
//==============================================================================
/** Provides the type of scoped lock to use for locking a SpinLock. */
using ScopedLockType = GenericScopedLock<SpinLock>;
/** Provides the type of scoped unlocker to use with a SpinLock. */
using ScopedUnlockType = GenericScopedUnlock<SpinLock>;
/** Provides the type of scoped try-lock to use for locking a SpinLock. */
using ScopedTryLockType = GenericScopedTryLock<SpinLock>;
private:
//==============================================================================
mutable Atomic<int> lock;
JUCE_DECLARE_NON_COPYABLE (SpinLock)
};
} // namespace juce