src/thread/windows/SDL_sysmutex.c - third_party/sdl - Git at Google

 /*
   Simple DirectMedia Layer
   Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>

   This software is provided 'as-is', without any express or implied
   warranty.  In no event will the authors be held liable for any damages
   arising from the use of this software.

   Permission is granted to anyone to use this software for any purpose,
   including commercial applications, and to alter it and redistribute it
   freely, subject to the following restrictions:

   1. The origin of this software must not be misrepresented; you must not
      claim that you wrote the original software. If you use this software
      in a product, an acknowledgment in the product documentation would be
      appreciated but is not required.
   2. Altered source versions must be plainly marked as such, and must not be
      misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
 */
 #include "../../SDL_internal.h"

 #if SDL_THREAD_WINDOWS

 /**
  * Mutex functions using the Win32 API
  * There are two implementations available based on:
  * - Critical Sections. Available on all OS versions since Windows XP.
  * - Slim Reader/Writer Locks. Requires Windows 7 or newer.
  * which are chosen at runtime.
  */


 #include "SDL_hints.h"

 #include "SDL_sysmutex_c.h"


 /* Implementation will be chosen at runtime based on available Kernel features */
 SDL_mutex_impl_t SDL_mutex_impl_active = {0};


 /**
  * Implementation based on Slim Reader/Writer (SRW) Locks for Win 7 and newer.
  */

 #if __WINRT__
 /* Functions are guaranteed to be available */
 #define pReleaseSRWLockExclusive ReleaseSRWLockExclusive
 #define pAcquireSRWLockExclusive AcquireSRWLockExclusive
 #define pTryAcquireSRWLockExclusive TryAcquireSRWLockExclusive
 #else
 typedef VOID(WINAPI *pfnReleaseSRWLockExclusive)(PSRWLOCK);
 typedef VOID(WINAPI *pfnAcquireSRWLockExclusive)(PSRWLOCK);
 typedef BOOLEAN(WINAPI *pfnTryAcquireSRWLockExclusive)(PSRWLOCK);
 static pfnReleaseSRWLockExclusive pReleaseSRWLockExclusive = NULL;
 static pfnAcquireSRWLockExclusive pAcquireSRWLockExclusive = NULL;
 static pfnTryAcquireSRWLockExclusive pTryAcquireSRWLockExclusive = NULL;
 #endif

 static SDL_mutex *
 SDL_CreateMutex_srw(void)
 {
     SDL_mutex_srw *mutex;

     /* Relies on SRWLOCK_INIT == 0. */
     mutex = (SDL_mutex_srw *) SDL_calloc(1, sizeof(*mutex));
     if (!mutex) {
         SDL_OutOfMemory();
     }

     return (SDL_mutex *)mutex;
 }

 static void
 SDL_DestroyMutex_srw(SDL_mutex * mutex)
 {
     if (mutex) {
         /* There are no kernel allocated resources */
         SDL_free(mutex);
     }
 }

 static int
 SDL_LockMutex_srw(SDL_mutex * _mutex)
 {
     SDL_mutex_srw *mutex = (SDL_mutex_srw *)_mutex;
     DWORD this_thread;

     if (mutex == NULL) {
         return SDL_SetError("Passed a NULL mutex");
     }

     this_thread = GetCurrentThreadId();
     if (mutex->owner == this_thread) {
         ++mutex->count;
     } else {
         /* The order of operations is important.
            We set the locking thread id after we obtain the lock
            so unlocks from other threads will fail.
          */
         pAcquireSRWLockExclusive(&mutex->srw);
         mutex->owner = this_thread;
         ++mutex->count;
     }
     return 0;
 }

 static int
 SDL_TryLockMutex_srw(SDL_mutex * _mutex)
 {
     SDL_mutex_srw *mutex = (SDL_mutex_srw *)_mutex;
     DWORD this_thread;
     int retval = 0;

     if (mutex == NULL) {
         return SDL_SetError("Passed a NULL mutex");
     }

     this_thread = GetCurrentThreadId();
     if (mutex->owner == this_thread) {
         ++mutex->count;
     } else {
         if (pTryAcquireSRWLockExclusive(&mutex->srw) != 0) {
             mutex->owner = this_thread;
             ++mutex->count;
         } else {
             retval = SDL_MUTEX_TIMEDOUT;
         }
     }
     return retval;
 }

 static int
 SDL_UnlockMutex_srw(SDL_mutex * _mutex)
 {
     SDL_mutex_srw *mutex = (SDL_mutex_srw *)_mutex;

     if (mutex == NULL) {
         return SDL_SetError("Passed a NULL mutex");
     }

     if (mutex->owner == GetCurrentThreadId()) {
         if (--mutex->count == 0) {
             mutex->owner = 0;
             pReleaseSRWLockExclusive(&mutex->srw);
         }
     } else {
         return SDL_SetError("mutex not owned by this thread");
     }

     return 0;
 }

 static const SDL_mutex_impl_t SDL_mutex_impl_srw =
 {
     &SDL_CreateMutex_srw,
     &SDL_DestroyMutex_srw,
     &SDL_LockMutex_srw,
     &SDL_TryLockMutex_srw,
     &SDL_UnlockMutex_srw,
     SDL_MUTEX_SRW,
 };


 /**
  * Fallback Mutex implementation using Critical Sections (before Win 7)
  */

 typedef struct SDL_mutex_cs
 {
     CRITICAL_SECTION cs;
 } SDL_mutex_cs;

 /* Create a mutex */
 static SDL_mutex *
 SDL_CreateMutex_cs(void)
 {
     SDL_mutex_cs *mutex;

     /* Allocate mutex memory */
     mutex = (SDL_mutex_cs *) SDL_malloc(sizeof(*mutex));
     if (mutex) {
         /* Initialize */
         /* On SMP systems, a non-zero spin count generally helps performance */
 #if __WINRT__
         InitializeCriticalSectionEx(&mutex->cs, 2000, 0);
 #else
         InitializeCriticalSectionAndSpinCount(&mutex->cs, 2000);
 #endif
     } else {
         SDL_OutOfMemory();
     }
     return (SDL_mutex *)mutex;
 }

 /* Free the mutex */
 static void
 SDL_DestroyMutex_cs(SDL_mutex * mutex_)
 {
     SDL_mutex_cs *mutex = (SDL_mutex_cs *)mutex_;
     if (mutex) {
         DeleteCriticalSection(&mutex->cs);
         SDL_free(mutex);
     }
 }

 /* Lock the mutex */
 static int
 SDL_LockMutex_cs(SDL_mutex * mutex_)
 {
     SDL_mutex_cs *mutex = (SDL_mutex_cs *)mutex_;
     if (mutex == NULL) {
         return SDL_SetError("Passed a NULL mutex");
     }

     EnterCriticalSection(&mutex->cs);
     return 0;
 }

 /* TryLock the mutex */
 static int
 SDL_TryLockMutex_cs(SDL_mutex * mutex_)
 {
     SDL_mutex_cs *mutex = (SDL_mutex_cs *)mutex_;
     int retval = 0;
     if (mutex == NULL) {
         return SDL_SetError("Passed a NULL mutex");
     }

     if (TryEnterCriticalSection(&mutex->cs) == 0) {
         retval = SDL_MUTEX_TIMEDOUT;
     }
     return retval;
 }

 /* Unlock the mutex */
 static int
 SDL_UnlockMutex_cs(SDL_mutex * mutex_)
 {
     SDL_mutex_cs *mutex = (SDL_mutex_cs *)mutex_;
     if (mutex == NULL) {
         return SDL_SetError("Passed a NULL mutex");
     }

     LeaveCriticalSection(&mutex->cs);
     return 0;
 }

 static const SDL_mutex_impl_t SDL_mutex_impl_cs =
 {
     &SDL_CreateMutex_cs,
     &SDL_DestroyMutex_cs,
     &SDL_LockMutex_cs,
     &SDL_TryLockMutex_cs,
     &SDL_UnlockMutex_cs,
     SDL_MUTEX_CS,
 };


 /**
  * Runtime selection and redirection
  */

 SDL_mutex *
 SDL_CreateMutex(void)
 {
     if (SDL_mutex_impl_active.Create == NULL) {
         /* Default to fallback implementation */
         const SDL_mutex_impl_t * impl = &SDL_mutex_impl_cs;

         if (!SDL_GetHintBoolean(SDL_HINT_WINDOWS_FORCE_MUTEX_CRITICAL_SECTIONS, SDL_FALSE)) {
 #if __WINRT__
             /* Link statically on this platform */
             impl = &SDL_mutex_impl_srw;
 #else
             /* Try faster implementation for Windows 7 and newer */
             HMODULE kernel32 = GetModuleHandle(TEXT("kernel32.dll"));
             if (kernel32) {
                 /* Requires Vista: */
                 pReleaseSRWLockExclusive = (pfnReleaseSRWLockExclusive) GetProcAddress(kernel32, "ReleaseSRWLockExclusive");
                 pAcquireSRWLockExclusive = (pfnAcquireSRWLockExclusive) GetProcAddress(kernel32, "AcquireSRWLockExclusive");
                 /* Requires 7: */
                 pTryAcquireSRWLockExclusive = (pfnTryAcquireSRWLockExclusive) GetProcAddress(kernel32, "TryAcquireSRWLockExclusive");
                 if (pReleaseSRWLockExclusive && pAcquireSRWLockExclusive && pTryAcquireSRWLockExclusive) {
                     impl = &SDL_mutex_impl_srw;
                 }
             }
 #endif
         }

         /* Copy instead of using pointer to save one level of indirection */
         SDL_memcpy(&SDL_mutex_impl_active, impl, sizeof(SDL_mutex_impl_active));
     }
     return SDL_mutex_impl_active.Create();
 }

 void
 SDL_DestroyMutex(SDL_mutex * mutex) {
     SDL_mutex_impl_active.Destroy(mutex);
 }

 int
 SDL_LockMutex(SDL_mutex * mutex) {
     return SDL_mutex_impl_active.Lock(mutex);
 }

 int
 SDL_TryLockMutex(SDL_mutex * mutex) {
     return SDL_mutex_impl_active.TryLock(mutex);
 }

 int
 SDL_UnlockMutex(SDL_mutex * mutex) {
     return SDL_mutex_impl_active.Unlock(mutex);
 }

 #endif /* SDL_THREAD_WINDOWS */

 /* vi: set ts=4 sw=4 expandtab: */
	/*
	Simple DirectMedia Layer
	Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>

	This software is provided 'as-is', without any express or implied
	warranty. In no event will the authors be held liable for any damages
	arising from the use of this software.

	Permission is granted to anyone to use this software for any purpose,
	including commercial applications, and to alter it and redistribute it
	freely, subject to the following restrictions:

	1. The origin of this software must not be misrepresented; you must not
	claim that you wrote the original software. If you use this software
	in a product, an acknowledgment in the product documentation would be
	appreciated but is not required.
	2. Altered source versions must be plainly marked as such, and must not be
	misrepresented as being the original software.
	3. This notice may not be removed or altered from any source distribution.
	*/
	#include "../../SDL_internal.h"

	#if SDL_THREAD_WINDOWS

	/**
	* Mutex functions using the Win32 API
	* There are two implementations available based on:
	* - Critical Sections. Available on all OS versions since Windows XP.
	* - Slim Reader/Writer Locks. Requires Windows 7 or newer.
	* which are chosen at runtime.
	*/


	#include "SDL_hints.h"

	#include "SDL_sysmutex_c.h"


	/* Implementation will be chosen at runtime based on available Kernel features */
	SDL_mutex_impl_t SDL_mutex_impl_active = {0};


	/**
	* Implementation based on Slim Reader/Writer (SRW) Locks for Win 7 and newer.
	*/

	#if __WINRT__
	/* Functions are guaranteed to be available */
	#define pReleaseSRWLockExclusive ReleaseSRWLockExclusive
	#define pAcquireSRWLockExclusive AcquireSRWLockExclusive
	#define pTryAcquireSRWLockExclusive TryAcquireSRWLockExclusive
	#else
	typedef VOID(WINAPI *pfnReleaseSRWLockExclusive)(PSRWLOCK);
	typedef VOID(WINAPI *pfnAcquireSRWLockExclusive)(PSRWLOCK);
	typedef BOOLEAN(WINAPI *pfnTryAcquireSRWLockExclusive)(PSRWLOCK);
	static pfnReleaseSRWLockExclusive pReleaseSRWLockExclusive = NULL;
	static pfnAcquireSRWLockExclusive pAcquireSRWLockExclusive = NULL;
	static pfnTryAcquireSRWLockExclusive pTryAcquireSRWLockExclusive = NULL;
	#endif

	static SDL_mutex *
	SDL_CreateMutex_srw(void)
	{
	SDL_mutex_srw *mutex;

	/* Relies on SRWLOCK_INIT == 0. */
	mutex = (SDL_mutex_srw ) SDL_calloc(1, sizeof(mutex));
	if (!mutex) {
	SDL_OutOfMemory();
	}

	return (SDL_mutex *)mutex;
	}

	static void
	SDL_DestroyMutex_srw(SDL_mutex * mutex)
	{
	if (mutex) {
	/* There are no kernel allocated resources */
	SDL_free(mutex);
	}
	}

	static int
	SDL_LockMutex_srw(SDL_mutex * _mutex)
	{
	SDL_mutex_srw mutex = (SDL_mutex_srw )_mutex;
	DWORD this_thread;

	if (mutex == NULL) {
	return SDL_SetError("Passed a NULL mutex");
	}

	this_thread = GetCurrentThreadId();
	if (mutex->owner == this_thread) {
	++mutex->count;
	} else {
	/* The order of operations is important.
	We set the locking thread id after we obtain the lock
	so unlocks from other threads will fail.
	*/
	pAcquireSRWLockExclusive(&mutex->srw);
	mutex->owner = this_thread;
	++mutex->count;
	}
	return 0;
	}

	static int
	SDL_TryLockMutex_srw(SDL_mutex * _mutex)
	{
	SDL_mutex_srw mutex = (SDL_mutex_srw )_mutex;
	DWORD this_thread;
	int retval = 0;

	if (mutex == NULL) {
	return SDL_SetError("Passed a NULL mutex");
	}

	this_thread = GetCurrentThreadId();
	if (mutex->owner == this_thread) {
	++mutex->count;
	} else {
	if (pTryAcquireSRWLockExclusive(&mutex->srw) != 0) {
	mutex->owner = this_thread;
	++mutex->count;
	} else {
	retval = SDL_MUTEX_TIMEDOUT;
	}
	}
	return retval;
	}

	static int
	SDL_UnlockMutex_srw(SDL_mutex * _mutex)
	{
	SDL_mutex_srw mutex = (SDL_mutex_srw )_mutex;

	if (mutex == NULL) {
	return SDL_SetError("Passed a NULL mutex");
	}

	if (mutex->owner == GetCurrentThreadId()) {
	if (--mutex->count == 0) {
	mutex->owner = 0;
	pReleaseSRWLockExclusive(&mutex->srw);
	}
	} else {
	return SDL_SetError("mutex not owned by this thread");
	}

	return 0;
	}

	static const SDL_mutex_impl_t SDL_mutex_impl_srw =
	{
	&SDL_CreateMutex_srw,
	&SDL_DestroyMutex_srw,
	&SDL_LockMutex_srw,
	&SDL_TryLockMutex_srw,
	&SDL_UnlockMutex_srw,
	SDL_MUTEX_SRW,
	};


	/**
	* Fallback Mutex implementation using Critical Sections (before Win 7)
	*/

	typedef struct SDL_mutex_cs
	{
	CRITICAL_SECTION cs;
	} SDL_mutex_cs;

	/* Create a mutex */
	static SDL_mutex *
	SDL_CreateMutex_cs(void)
	{
	SDL_mutex_cs *mutex;

	/* Allocate mutex memory */
	mutex = (SDL_mutex_cs ) SDL_malloc(sizeof(mutex));
	if (mutex) {
	/* Initialize */
	/* On SMP systems, a non-zero spin count generally helps performance */
	#if __WINRT__
	InitializeCriticalSectionEx(&mutex->cs, 2000, 0);
	#else
	InitializeCriticalSectionAndSpinCount(&mutex->cs, 2000);
	#endif
	} else {
	SDL_OutOfMemory();
	}
	return (SDL_mutex *)mutex;
	}

	/* Free the mutex */
	static void
	SDL_DestroyMutex_cs(SDL_mutex * mutex_)
	{
	SDL_mutex_cs mutex = (SDL_mutex_cs )mutex_;
	if (mutex) {
	DeleteCriticalSection(&mutex->cs);
	SDL_free(mutex);
	}
	}

	/* Lock the mutex */
	static int
	SDL_LockMutex_cs(SDL_mutex * mutex_)
	{
	SDL_mutex_cs mutex = (SDL_mutex_cs )mutex_;
	if (mutex == NULL) {
	return SDL_SetError("Passed a NULL mutex");
	}

	EnterCriticalSection(&mutex->cs);
	return 0;
	}

	/* TryLock the mutex */
	static int
	SDL_TryLockMutex_cs(SDL_mutex * mutex_)
	{
	SDL_mutex_cs mutex = (SDL_mutex_cs )mutex_;
	int retval = 0;
	if (mutex == NULL) {
	return SDL_SetError("Passed a NULL mutex");
	}

	if (TryEnterCriticalSection(&mutex->cs) == 0) {
	retval = SDL_MUTEX_TIMEDOUT;
	}
	return retval;
	}

	/* Unlock the mutex */
	static int
	SDL_UnlockMutex_cs(SDL_mutex * mutex_)
	{
	SDL_mutex_cs mutex = (SDL_mutex_cs )mutex_;
	if (mutex == NULL) {
	return SDL_SetError("Passed a NULL mutex");
	}

	LeaveCriticalSection(&mutex->cs);
	return 0;
	}

	static const SDL_mutex_impl_t SDL_mutex_impl_cs =
	{
	&SDL_CreateMutex_cs,
	&SDL_DestroyMutex_cs,
	&SDL_LockMutex_cs,
	&SDL_TryLockMutex_cs,
	&SDL_UnlockMutex_cs,
	SDL_MUTEX_CS,
	};


	/**
	* Runtime selection and redirection
	*/

	SDL_mutex *
	SDL_CreateMutex(void)
	{
	if (SDL_mutex_impl_active.Create == NULL) {
	/* Default to fallback implementation */
	const SDL_mutex_impl_t * impl = &SDL_mutex_impl_cs;

	if (!SDL_GetHintBoolean(SDL_HINT_WINDOWS_FORCE_MUTEX_CRITICAL_SECTIONS, SDL_FALSE)) {
	#if __WINRT__
	/* Link statically on this platform */
	impl = &SDL_mutex_impl_srw;
	#else
	/* Try faster implementation for Windows 7 and newer */
	HMODULE kernel32 = GetModuleHandle(TEXT("kernel32.dll"));
	if (kernel32) {
	/* Requires Vista: */
	pReleaseSRWLockExclusive = (pfnReleaseSRWLockExclusive) GetProcAddress(kernel32, "ReleaseSRWLockExclusive");
	pAcquireSRWLockExclusive = (pfnAcquireSRWLockExclusive) GetProcAddress(kernel32, "AcquireSRWLockExclusive");
	/* Requires 7: */
	pTryAcquireSRWLockExclusive = (pfnTryAcquireSRWLockExclusive) GetProcAddress(kernel32, "TryAcquireSRWLockExclusive");
	if (pReleaseSRWLockExclusive && pAcquireSRWLockExclusive && pTryAcquireSRWLockExclusive) {
	impl = &SDL_mutex_impl_srw;
	}
	}
	#endif
	}

	/* Copy instead of using pointer to save one level of indirection */
	SDL_memcpy(&SDL_mutex_impl_active, impl, sizeof(SDL_mutex_impl_active));
	}
	return SDL_mutex_impl_active.Create();
	}

	void
	SDL_DestroyMutex(SDL_mutex * mutex) {
	SDL_mutex_impl_active.Destroy(mutex);
	}

	int
	SDL_LockMutex(SDL_mutex * mutex) {
	return SDL_mutex_impl_active.Lock(mutex);
	}

	int
	SDL_TryLockMutex(SDL_mutex * mutex) {
	return SDL_mutex_impl_active.TryLock(mutex);
	}

	int
	SDL_UnlockMutex(SDL_mutex * mutex) {
	return SDL_mutex_impl_active.Unlock(mutex);
	}

	#endif /* SDL_THREAD_WINDOWS */

	/* vi: set ts=4 sw=4 expandtab: */