86 lines
3.1 KiB
C++
86 lines
3.1 KiB
C++
/*
|
|
==============================================================================
|
|
|
|
This file is part of the JUCE library.
|
|
Copyright (c) 2017 - ROLI Ltd.
|
|
|
|
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() noexcept {}
|
|
inline ~SpinLock() noexcept {}
|
|
|
|
/** 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. */
|
|
typedef GenericScopedLock <SpinLock> ScopedLockType;
|
|
|
|
/** Provides the type of scoped unlocker to use with a SpinLock. */
|
|
typedef GenericScopedUnlock <SpinLock> ScopedUnlockType;
|
|
|
|
private:
|
|
//==============================================================================
|
|
mutable Atomic<int> lock;
|
|
|
|
JUCE_DECLARE_NON_COPYABLE (SpinLock)
|
|
};
|
|
|
|
} // namespace juce
|