thodg/libgit2/src/win32/thread.c

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• Hash : aab266c9
  Author :
  Date : 2016-06-20T20:07:33
  

  threads: add platform-independent thread initialization function

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• src/win32/thread.c

• /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #include "thread.h"
  #include "../global.h"
  
  #define CLEAN_THREAD_EXIT 0x6F012842
  
  typedef void (WINAPI *win32_srwlock_fn)(GIT_SRWLOCK *);
  
  static win32_srwlock_fn win32_srwlock_initialize;
  static win32_srwlock_fn win32_srwlock_acquire_shared;
  static win32_srwlock_fn win32_srwlock_release_shared;
  static win32_srwlock_fn win32_srwlock_acquire_exclusive;
  static win32_srwlock_fn win32_srwlock_release_exclusive;
  
  /* The thread procedure stub used to invoke the caller's procedure
   * and capture the return value for later collection. Windows will
   * only hold a DWORD, but we need to be able to store an entire
   * void pointer. This requires the indirection. */
  static DWORD WINAPI git_win32__threadproc(LPVOID lpParameter)
  {
  	git_thread *thread = lpParameter;
  
  	thread->result = thread->proc(thread->param);
  
  	git__free_tls_data();
  
  	return CLEAN_THREAD_EXIT;
  }
  
  int git_threads_init(void)
  {
  	HMODULE hModule = GetModuleHandleW(L"kernel32");
  
  	if (hModule) {
  		win32_srwlock_initialize = (win32_srwlock_fn)
  			GetProcAddress(hModule, "InitializeSRWLock");
  		win32_srwlock_acquire_shared = (win32_srwlock_fn)
  			GetProcAddress(hModule, "AcquireSRWLockShared");
  		win32_srwlock_release_shared = (win32_srwlock_fn)
  			GetProcAddress(hModule, "ReleaseSRWLockShared");
  		win32_srwlock_acquire_exclusive = (win32_srwlock_fn)
  			GetProcAddress(hModule, "AcquireSRWLockExclusive");
  		win32_srwlock_release_exclusive = (win32_srwlock_fn)
  			GetProcAddress(hModule, "ReleaseSRWLockExclusive");
  	}
  
  	return 0;
  }
  
  int git_thread_create(
  	git_thread *GIT_RESTRICT thread,
  	void *(*start_routine)(void*),
  	void *GIT_RESTRICT arg)
  {
  	thread->result = NULL;
  	thread->param = arg;
  	thread->proc = start_routine;
  	thread->thread = CreateThread(
  		NULL, 0, git_win32__threadproc, thread, 0, NULL);
  
  	return thread->thread ? 0 : -1;
  }
  
  int git_thread_join(
  	git_thread *thread,
  	void **value_ptr)
  {
  	DWORD exit;
  
  	if (WaitForSingleObject(thread->thread, INFINITE) != WAIT_OBJECT_0)
  		return -1;
  
  	if (!GetExitCodeThread(thread->thread, &exit)) {
  		CloseHandle(thread->thread);
  		return -1;
  	}
  
  	/* Check for the thread having exited uncleanly. If exit was unclean,
  	 * then we don't have a return value to give back to the caller. */
  	if (exit != CLEAN_THREAD_EXIT) {
  		assert(false);
  		thread->result = NULL;
  	}
  
  	if (value_ptr)
  		*value_ptr = thread->result;
  
  	CloseHandle(thread->thread);
  	return 0;
  }
  
  int git_mutex_init(git_mutex *GIT_RESTRICT mutex)
  {
  	InitializeCriticalSection(mutex);
  	return 0;
  }
  
  int git_mutex_free(git_mutex *mutex)
  {
  	DeleteCriticalSection(mutex);
  	return 0;
  }
  
  int git_mutex_lock(git_mutex *mutex)
  {
  	EnterCriticalSection(mutex);
  	return 0;
  }
  
  int git_mutex_unlock(git_mutex *mutex)
  {
  	LeaveCriticalSection(mutex);
  	return 0;
  }
  
  int git_cond_init(git_cond *cond)
  {
  	/* This is an auto-reset event. */
  	*cond = CreateEventW(NULL, FALSE, FALSE, NULL);
  	assert(*cond);
  
  	/* If we can't create the event, claim that the reason was out-of-memory.
  	 * The actual reason can be fetched with GetLastError(). */
  	return *cond ? 0 : ENOMEM;
  }
  
  int git_cond_free(git_cond *cond)
  {
  	BOOL closed;
  
  	if (!cond)
  		return EINVAL;
  
  	closed = CloseHandle(*cond);
  	assert(closed);
  	GIT_UNUSED(closed);
  
  	*cond = NULL;
  	return 0;
  }
  
  int git_cond_wait(git_cond *cond, git_mutex *mutex)
  {
  	int error;
  	DWORD wait_result;
  
  	if (!cond || !mutex)
  		return EINVAL;
  
  	/* The caller must be holding the mutex. */
  	error = git_mutex_unlock(mutex);
  
  	if (error)
  		return error;
  
  	wait_result = WaitForSingleObject(*cond, INFINITE);
  	assert(WAIT_OBJECT_0 == wait_result);
  	GIT_UNUSED(wait_result);
  
  	return git_mutex_lock(mutex);
  }
  
  int git_cond_signal(git_cond *cond)
  {
  	BOOL signaled;
  
  	if (!cond)
  		return EINVAL;
  
  	signaled = SetEvent(*cond);
  	assert(signaled);
  	GIT_UNUSED(signaled);
  
  	return 0;
  }
  
  int git_rwlock_init(git_rwlock *GIT_RESTRICT lock)
  {
  	if (win32_srwlock_initialize)
  		win32_srwlock_initialize(&lock->native.srwl);
  	else
  		InitializeCriticalSection(&lock->native.csec);
  
  	return 0;
  }
  
  int git_rwlock_rdlock(git_rwlock *lock)
  {
  	if (win32_srwlock_acquire_shared)
  		win32_srwlock_acquire_shared(&lock->native.srwl);
  	else
  		EnterCriticalSection(&lock->native.csec);
  
  	return 0;
  }
  
  int git_rwlock_rdunlock(git_rwlock *lock)
  {
  	if (win32_srwlock_release_shared)
  		win32_srwlock_release_shared(&lock->native.srwl);
  	else
  		LeaveCriticalSection(&lock->native.csec);
  
  	return 0;
  }
  
  int git_rwlock_wrlock(git_rwlock *lock)
  {
  	if (win32_srwlock_acquire_exclusive)
  		win32_srwlock_acquire_exclusive(&lock->native.srwl);
  	else
  		EnterCriticalSection(&lock->native.csec);
  
  	return 0;
  }
  
  int git_rwlock_wrunlock(git_rwlock *lock)
  {
  	if (win32_srwlock_release_exclusive)
  		win32_srwlock_release_exclusive(&lock->native.srwl);
  	else
  		LeaveCriticalSection(&lock->native.csec);
  
  	return 0;
  }
  
  int git_rwlock_free(git_rwlock *lock)
  {
  	if (!win32_srwlock_initialize)
  		DeleteCriticalSection(&lock->native.csec);
  	git__memzero(lock, sizeof(*lock));
  	return 0;
  }
  

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