pthread.c 5.39 KB
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/*
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 * Copyright (C) the libgit2 contributors. All rights reserved.
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 *
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 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
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 */

#include "pthread.h"
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#include "../global.h"
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int pthread_create(
	pthread_t *GIT_RESTRICT thread,
	const pthread_attr_t *GIT_RESTRICT attr,
	void *(*start_routine)(void*),
	void *GIT_RESTRICT arg)
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{
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	GIT_UNUSED(attr);
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	*thread = CreateThread(
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		NULL, 0, (LPTHREAD_START_ROUTINE)start_routine, arg, 0, NULL);
	return *thread ? 0 : -1;
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}

int pthread_join(pthread_t thread, void **value_ptr)
{
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	DWORD ret = WaitForSingleObject(thread, INFINITE);

	if (ret == WAIT_OBJECT_0) {
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		if (value_ptr != NULL) {
			*value_ptr = NULL;
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			GetExitCodeThread(thread, (void *)value_ptr);
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		}
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		CloseHandle(thread);
		return 0;
	}

	return -1;
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}

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int pthread_mutex_init(
	pthread_mutex_t *GIT_RESTRICT mutex,
	const pthread_mutexattr_t *GIT_RESTRICT mutexattr)
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{
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	GIT_UNUSED(mutexattr);
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	InitializeCriticalSection(mutex);
	return 0;
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}

int pthread_mutex_destroy(pthread_mutex_t *mutex)
{
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	DeleteCriticalSection(mutex);
	return 0;
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}

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int pthread_mutex_lock(pthread_mutex_t *mutex)
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{
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	EnterCriticalSection(mutex);
	return 0;
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}

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int pthread_mutex_unlock(pthread_mutex_t *mutex)
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{
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	LeaveCriticalSection(mutex);
	return 0;
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}

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int pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr)
{
	/* We don't support non-default attributes. */
	if (attr)
		return EINVAL;

	/* 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 pthread_cond_destroy(pthread_cond_t *cond)
{
	BOOL closed;

	if (!cond)
		return EINVAL;

	closed = CloseHandle(*cond);
	assert(closed);
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	GIT_UNUSED(closed);
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	*cond = NULL;
	return 0;
}

int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
	int error;
	DWORD wait_result;

	if (!cond || !mutex)
		return EINVAL;

	/* The caller must be holding the mutex. */
	error = pthread_mutex_unlock(mutex);

	if (error)
		return error;

	wait_result = WaitForSingleObject(*cond, INFINITE);
	assert(WAIT_OBJECT_0 == wait_result);
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	GIT_UNUSED(wait_result);
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	return pthread_mutex_lock(mutex);
}

int pthread_cond_signal(pthread_cond_t *cond)
{
	BOOL signaled;

	if (!cond)
		return EINVAL;

	signaled = SetEvent(*cond);
	assert(signaled);
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	GIT_UNUSED(signaled);
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	return 0;
}

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/* pthread_cond_broadcast is not implemented because doing so with just
 * Win32 events is quite complicated, and no caller in libgit2 uses it
 * yet.
 */
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int pthread_num_processors_np(void)
{
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	DWORD_PTR p, s;
	int n = 0;
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	if (GetProcessAffinityMask(GetCurrentProcess(), &p, &s))
		for (; p; p >>= 1)
			n += p&1;
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	return n ? n : 1;
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}

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static HINSTANCE win32_kernel32_dll;

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typedef void (WINAPI *win32_srwlock_fn)(GIT_SRWLOCK *);
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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;

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int pthread_rwlock_init(
	pthread_rwlock_t *GIT_RESTRICT lock,
	const pthread_rwlockattr_t *GIT_RESTRICT attr)
{
	(void)attr;
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	if (win32_srwlock_initialize)
		win32_srwlock_initialize(&lock->native.srwl);
	else
		InitializeCriticalSection(&lock->native.csec);

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	return 0;
}

int pthread_rwlock_rdlock(pthread_rwlock_t *lock)
{
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	if (win32_srwlock_acquire_shared)
		win32_srwlock_acquire_shared(&lock->native.srwl);
	else
		EnterCriticalSection(&lock->native.csec);

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	return 0;
}

int pthread_rwlock_rdunlock(pthread_rwlock_t *lock)
{
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	if (win32_srwlock_release_shared)
		win32_srwlock_release_shared(&lock->native.srwl);
	else
		LeaveCriticalSection(&lock->native.csec);

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	return 0;
}

int pthread_rwlock_wrlock(pthread_rwlock_t *lock)
{
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	if (win32_srwlock_acquire_exclusive)
		win32_srwlock_acquire_exclusive(&lock->native.srwl);
	else
		EnterCriticalSection(&lock->native.csec);

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	return 0;
}

int pthread_rwlock_wrunlock(pthread_rwlock_t *lock)
{
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	if (win32_srwlock_release_exclusive)
		win32_srwlock_release_exclusive(&lock->native.srwl);
	else
		LeaveCriticalSection(&lock->native.csec);

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	return 0;
}

int pthread_rwlock_destroy(pthread_rwlock_t *lock)
{
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	if (!win32_srwlock_initialize)
		DeleteCriticalSection(&lock->native.csec);
	git__memzero(lock, sizeof(*lock));
	return 0;
}


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static void win32_pthread_shutdown(void)
{
	if (win32_kernel32_dll) {
		FreeLibrary(win32_kernel32_dll);
		win32_kernel32_dll = NULL;
	}
}

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int win32_pthread_initialize(void)
{
	if (win32_kernel32_dll)
		return 0;

	win32_kernel32_dll = LoadLibrary("Kernel32.dll");
	if (!win32_kernel32_dll) {
		giterr_set(GITERR_OS, "Could not load Kernel32.dll!");
		return -1;
	}

	win32_srwlock_initialize = (win32_srwlock_fn)
		GetProcAddress(win32_kernel32_dll, "InitializeSRWLock");
	win32_srwlock_acquire_shared = (win32_srwlock_fn)
		GetProcAddress(win32_kernel32_dll, "AcquireSRWLockShared");
	win32_srwlock_release_shared = (win32_srwlock_fn)
		GetProcAddress(win32_kernel32_dll, "ReleaseSRWLockShared");
	win32_srwlock_acquire_exclusive = (win32_srwlock_fn)
		GetProcAddress(win32_kernel32_dll, "AcquireSRWLockExclusive");
	win32_srwlock_release_exclusive = (win32_srwlock_fn)
		GetProcAddress(win32_kernel32_dll, "ReleaseSRWLockExclusive");

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	git__on_shutdown(win32_pthread_shutdown);
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	return 0;
}