86 lines
3.1 KiB
C++
86 lines
3.1 KiB
C++
/*
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==============================================================================
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This file is part of the JUCE library.
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Copyright (c) 2017 - ROLI Ltd.
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JUCE is an open source library subject to commercial or open-source
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licensing.
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The code included in this file is provided under the terms of the ISC license
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http://www.isc.org/downloads/software-support-policy/isc-license. Permission
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To use, copy, modify, and/or distribute this software for any purpose with or
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without fee is hereby granted provided that the above copyright notice and
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this permission notice appear in all copies.
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JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
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EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
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DISCLAIMED.
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==============================================================================
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*/
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namespace juce
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{
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//==============================================================================
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/**
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A simple spin-lock class that can be used as a simple, low-overhead mutex for
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uncontended situations.
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Note that unlike a CriticalSection, this type of lock is not re-entrant, and may
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be less efficient when used in a highly contended situation, but it's very small and
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requires almost no initialisation.
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It's most appropriate for simple situations where you're only going to hold the
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lock for a very brief time.
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@see CriticalSection
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@tags{Core}
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*/
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class JUCE_API SpinLock
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{
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public:
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inline SpinLock() = default;
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inline ~SpinLock() = default;
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/** Acquires the lock.
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This will block until the lock has been successfully acquired by this thread.
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Note that a SpinLock is NOT re-entrant, and is not smart enough to know whether the
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caller thread already has the lock - so if a thread tries to acquire a lock that it
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already holds, this method will never return!
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It's strongly recommended that you never call this method directly - instead use the
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ScopedLockType class to manage the locking using an RAII pattern instead.
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*/
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void enter() const noexcept;
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/** Attempts to acquire the lock, returning true if this was successful. */
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inline bool tryEnter() const noexcept
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{
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return lock.compareAndSetBool (1, 0);
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}
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/** Releases the lock. */
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inline void exit() const noexcept
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{
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jassert (lock.get() == 1); // Agh! Releasing a lock that isn't currently held!
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lock = 0;
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}
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//==============================================================================
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/** Provides the type of scoped lock to use for locking a SpinLock. */
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using ScopedLockType = GenericScopedLock<SpinLock>;
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/** Provides the type of scoped unlocker to use with a SpinLock. */
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using ScopedUnlockType = GenericScopedUnlock<SpinLock>;
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private:
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//==============================================================================
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mutable Atomic<int> lock;
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JUCE_DECLARE_NON_COPYABLE (SpinLock)
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};
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} // namespace juce
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