132 lines
2.5 KiB
C++
132 lines
2.5 KiB
C++
/**
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\file G3D/GMutex.h
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\created 2005-09-22
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\edited 2013-04-03
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*/
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#ifndef G3D_GMutex_h
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#define G3D_GMutex_h
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#include "G3D/platform.h"
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#include "G3D/AtomicInt32.h"
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#include "G3D/debugAssert.h"
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#include <string>
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#ifndef G3D_WINDOWS
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# include <pthread.h>
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# include <signal.h>
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#endif
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#if defined(G3D_LINUX) || defined(G3D_OSX)
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# include <unistd.h> // For usleep
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#endif
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namespace G3D {
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/**
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\brief A mutual exclusion lock that busy-waits when locking.
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On a machine with one (significant) thread per processor core,
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a Spinlock may be substantially faster than a mutex.
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\sa G3D::GThread, G3D::GMutex, G3D::AtomicInt32
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*/
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class Spinlock {
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private:
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AtomicInt32 x;
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public:
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inline Spinlock() : x(0) {}
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/** Busy waits until the lock is unlocked, then locks it
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exclusively. Returns true if the lock succeeded on the first
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try (indicating no contention).
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Unlike a G3D::GMutex, a single thread cannot re-enter
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Spinlock::lock() that it already locked.
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*/
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inline bool lock() {
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bool first = true;
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while (x.compareAndSet(0, 1) == 1) {
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first = false;
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# ifdef G3D_WINDOWS
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Sleep(0);
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# else
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usleep(0);
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# endif
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}
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return first;
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}
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inline void unlock() {
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x.compareAndSet(1, 0);
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}
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};
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/**
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\brief Mutual exclusion lock used for synchronization.
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@sa G3D::GThread, G3D::AtomicInt32, G3D::Spinlock
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*/
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class GMutex {
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private:
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# ifdef G3D_WINDOWS
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CRITICAL_SECTION m_handle;
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# else
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pthread_mutex_t m_handle;
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pthread_mutexattr_t m_attr;
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# endif
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// Not implemented on purpose, don't use
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GMutex(const GMutex &mlock);
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GMutex &operator=(const GMutex &);
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bool operator==(const GMutex&);
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public:
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GMutex();
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~GMutex();
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/** Locks the mutex or blocks until available. */
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void lock();
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/** Locks the mutex if it not already locked.
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Returns true if lock successful, false otherwise. */
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bool tryLock();
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/** Unlocks the mutex. */
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void unlock();
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};
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/**
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Automatically locks while in scope.
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*/
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class GMutexLock {
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private:
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GMutex* m;
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// Not implemented on purpose, don't use
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GMutexLock(const GMutexLock &mlock);
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GMutexLock &operator=(const GMutexLock &);
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bool operator==(const GMutexLock&);
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public:
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GMutexLock(GMutex* mutex) {
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m = mutex;
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m->lock();
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}
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~GMutexLock() {
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m->unlock();
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}
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};
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} // G3D
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#endif
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