FreeRDP/winpr/libwinpr/synch/critical.c

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/**
* WinPR: Windows Portable Runtime
* Synchronization Functions
*
* Copyright 2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
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* Copyright 2013 Norbert Federa <norbert.federa@thincast.com>
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*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
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#include <winpr/config.h>
#include <winpr/assert.h>
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#include <winpr/tchar.h>
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#include <winpr/synch.h>
#include <winpr/sysinfo.h>
#include <winpr/interlocked.h>
#include <winpr/thread.h>
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#include "synch.h"
#ifdef WINPR_HAVE_UNISTD_H
#include <unistd.h>
#endif
#if defined(__APPLE__)
#include <mach/task.h>
#include <mach/mach.h>
#include <mach/semaphore.h>
#endif
#ifndef _WIN32
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#include "../log.h"
#define TAG WINPR_TAG("synch.critical")
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VOID InitializeCriticalSection(LPCRITICAL_SECTION lpCriticalSection)
{
InitializeCriticalSectionEx(lpCriticalSection, 0, 0);
}
BOOL InitializeCriticalSectionEx(LPCRITICAL_SECTION lpCriticalSection, DWORD dwSpinCount,
DWORD Flags)
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{
WINPR_ASSERT(lpCriticalSection);
/**
* See http://msdn.microsoft.com/en-us/library/ff541979(v=vs.85).aspx
* - The LockCount field indicates the number of times that any thread has
* called the EnterCriticalSection routine for this critical section,
* minus one. This field starts at -1 for an unlocked critical section.
* Each call of EnterCriticalSection increments this value; each call of
* LeaveCriticalSection decrements it.
* - The RecursionCount field indicates the number of times that the owning
* thread has called EnterCriticalSection for this critical section.
*/
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if (Flags != 0)
{
WLog_WARN(TAG, "Flags unimplemented");
}
lpCriticalSection->DebugInfo = NULL;
lpCriticalSection->LockCount = -1;
lpCriticalSection->SpinCount = 0;
lpCriticalSection->RecursionCount = 0;
lpCriticalSection->OwningThread = NULL;
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lpCriticalSection->LockSemaphore = (winpr_sem_t*)malloc(sizeof(winpr_sem_t));
if (!lpCriticalSection->LockSemaphore)
return FALSE;
#if defined(__APPLE__)
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if (semaphore_create(mach_task_self(), lpCriticalSection->LockSemaphore, SYNC_POLICY_FIFO, 0) !=
KERN_SUCCESS)
goto out_fail;
#else
if (sem_init(lpCriticalSection->LockSemaphore, 0, 0) != 0)
goto out_fail;
#endif
SetCriticalSectionSpinCount(lpCriticalSection, dwSpinCount);
return TRUE;
out_fail:
free(lpCriticalSection->LockSemaphore);
return FALSE;
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}
BOOL InitializeCriticalSectionAndSpinCount(LPCRITICAL_SECTION lpCriticalSection, DWORD dwSpinCount)
{
return InitializeCriticalSectionEx(lpCriticalSection, dwSpinCount, 0);
}
DWORD SetCriticalSectionSpinCount(LPCRITICAL_SECTION lpCriticalSection, DWORD dwSpinCount)
{
WINPR_ASSERT(lpCriticalSection);
#if !defined(WINPR_CRITICAL_SECTION_DISABLE_SPINCOUNT)
SYSTEM_INFO sysinfo;
DWORD dwPreviousSpinCount = lpCriticalSection->SpinCount;
if (dwSpinCount)
{
/* Don't spin on uniprocessor systems! */
GetNativeSystemInfo(&sysinfo);
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if (sysinfo.dwNumberOfProcessors < 2)
dwSpinCount = 0;
}
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lpCriticalSection->SpinCount = dwSpinCount;
return dwPreviousSpinCount;
#else
return 0;
#endif
}
static VOID _WaitForCriticalSection(LPCRITICAL_SECTION lpCriticalSection)
{
WINPR_ASSERT(lpCriticalSection);
#if defined(__APPLE__)
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semaphore_wait(*((winpr_sem_t*)lpCriticalSection->LockSemaphore));
#else
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sem_wait((winpr_sem_t*)lpCriticalSection->LockSemaphore);
#endif
}
static VOID _UnWaitCriticalSection(LPCRITICAL_SECTION lpCriticalSection)
{
WINPR_ASSERT(lpCriticalSection);
#if defined __APPLE__
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semaphore_signal(*((winpr_sem_t*)lpCriticalSection->LockSemaphore));
#else
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sem_post((winpr_sem_t*)lpCriticalSection->LockSemaphore);
#endif
}
VOID EnterCriticalSection(LPCRITICAL_SECTION lpCriticalSection)
{
WINPR_ASSERT(lpCriticalSection);
#if !defined(WINPR_CRITICAL_SECTION_DISABLE_SPINCOUNT)
ULONG SpinCount = lpCriticalSection->SpinCount;
/* If we're lucky or if the current thread is already owner we can return early */
if (SpinCount && TryEnterCriticalSection(lpCriticalSection))
return;
/* Spin requested times but don't compete with another waiting thread */
while (SpinCount-- && lpCriticalSection->LockCount < 1)
{
/* Atomically try to acquire and check the if the section is free. */
if (InterlockedCompareExchange(&lpCriticalSection->LockCount, 0, -1) == -1)
{
lpCriticalSection->RecursionCount = 1;
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lpCriticalSection->OwningThread = (HANDLE)(ULONG_PTR)GetCurrentThreadId();
return;
}
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/* Failed to get the lock. Let the scheduler know that we're spinning. */
if (sched_yield() != 0)
{
/**
* On some operating systems sched_yield is a stub.
* usleep should at least trigger a context switch if any thread is waiting.
* A ThreadYield() would be nice in winpr ...
*/
usleep(1);
}
}
#endif
/* First try the fastest possible path to get the lock. */
if (InterlockedIncrement(&lpCriticalSection->LockCount))
{
/* Section is already locked. Check if it is owned by the current thread. */
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if (lpCriticalSection->OwningThread == (HANDLE)(ULONG_PTR)GetCurrentThreadId())
{
/* Recursion. No need to wait. */
lpCriticalSection->RecursionCount++;
return;
}
/* Section is locked by another thread. We have to wait. */
_WaitForCriticalSection(lpCriticalSection);
}
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/* We got the lock. Own it ... */
lpCriticalSection->RecursionCount = 1;
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lpCriticalSection->OwningThread = (HANDLE)(ULONG_PTR)GetCurrentThreadId();
}
BOOL TryEnterCriticalSection(LPCRITICAL_SECTION lpCriticalSection)
{
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HANDLE current_thread = (HANDLE)(ULONG_PTR)GetCurrentThreadId();
WINPR_ASSERT(lpCriticalSection);
/* Atomically acquire the the lock if the section is free. */
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if (InterlockedCompareExchange(&lpCriticalSection->LockCount, 0, -1) == -1)
{
lpCriticalSection->RecursionCount = 1;
lpCriticalSection->OwningThread = current_thread;
return TRUE;
}
/* Section is already locked. Check if it is owned by the current thread. */
if (lpCriticalSection->OwningThread == current_thread)
{
/* Recursion, return success */
lpCriticalSection->RecursionCount++;
InterlockedIncrement(&lpCriticalSection->LockCount);
return TRUE;
}
return FALSE;
}
VOID LeaveCriticalSection(LPCRITICAL_SECTION lpCriticalSection)
{
WINPR_ASSERT(lpCriticalSection);
/* Decrement RecursionCount and check if this is the last LeaveCriticalSection call ...*/
if (--lpCriticalSection->RecursionCount < 1)
{
/* Last recursion, clear owner, unlock and if there are other waiting threads ... */
lpCriticalSection->OwningThread = NULL;
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if (InterlockedDecrement(&lpCriticalSection->LockCount) >= 0)
{
/* ...signal the semaphore to unblock the next waiting thread */
_UnWaitCriticalSection(lpCriticalSection);
}
}
else
{
InterlockedDecrement(&lpCriticalSection->LockCount);
}
}
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VOID DeleteCriticalSection(LPCRITICAL_SECTION lpCriticalSection)
{
WINPR_ASSERT(lpCriticalSection);
lpCriticalSection->LockCount = -1;
lpCriticalSection->SpinCount = 0;
lpCriticalSection->RecursionCount = 0;
lpCriticalSection->OwningThread = NULL;
if (lpCriticalSection->LockSemaphore != NULL)
{
#if defined __APPLE__
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semaphore_destroy(mach_task_self(), *((winpr_sem_t*)lpCriticalSection->LockSemaphore));
#else
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sem_destroy((winpr_sem_t*)lpCriticalSection->LockSemaphore);
#endif
free(lpCriticalSection->LockSemaphore);
lpCriticalSection->LockSemaphore = NULL;
}
}
#endif