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