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cpl_multiproc.cpp
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/**********************************************************************
*
* Project: CPL - Common Portability Library
* Purpose: CPL Multi-Threading, and process handling portability functions.
* Author: Frank Warmerdam, [email protected]
*
**********************************************************************
* Copyright (c) 2002, Frank Warmerdam
* Copyright (c) 2009-2013, Even Rouault <even dot rouault at spatialys.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
****************************************************************************/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
// Include cpl_config.h BEFORE cpl_multiproc.h, as the later may undefine
// CPL_MULTIPROC_PTHREAD for mingw case.
#include "cpl_config.h"
#include "cpl_multiproc.h"
#ifdef CHECK_THREAD_CAN_ALLOCATE_TLS
#include <cassert>
#endif
#include <cerrno>
#include <cmath>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <algorithm>
#include "cpl_atomic_ops.h"
#include "cpl_conv.h"
#include "cpl_error.h"
#include "cpl_string.h"
#include "cpl_vsi.h"
#if defined(CPL_MULTIPROC_STUB) && !defined(DEBUG)
#define MUTEX_NONE
#endif
// #define DEBUG_MUTEX
#if defined(DEBUG) && \
(defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)))
#ifndef DEBUG_CONTENTION
#define DEBUG_CONTENTION
#endif
#endif
typedef struct _CPLSpinLock CPLSpinLock;
struct _CPLLock
{
CPLLockType eType;
union
{
CPLMutex *hMutex;
CPLSpinLock *hSpinLock;
} u;
#ifdef DEBUG_CONTENTION
bool bDebugPerfAsked;
bool bDebugPerf;
volatile int nCurrentHolders;
GUIntBig nStartTime;
GIntBig nMaxDiff;
double dfAvgDiff;
GUIntBig nIters;
#endif
};
#ifdef DEBUG_CONTENTION
#if defined(__x86_64)
#define GCC_CPUID(level, a, b, c, d) \
__asm__ volatile("xchgq %%rbx, %q1\n" \
"cpuid\n" \
"xchgq %%rbx, %q1" \
: "=a"(a), "=r"(b), "=c"(c), "=d"(d) \
: "0"(level))
#else
#define GCC_CPUID(level, a, b, c, d) \
__asm__ volatile("xchgl %%ebx, %1\n" \
"cpuid\n" \
"xchgl %%ebx, %1" \
: "=a"(a), "=r"(b), "=c"(c), "=d"(d) \
: "0"(level))
#endif
static GUIntBig CPLrdtsc()
{
unsigned int a;
unsigned int d;
unsigned int unused1;
unsigned int unused2;
unsigned int unused3;
unsigned int unused4;
GCC_CPUID(0, unused1, unused2, unused3, unused4);
__asm__ volatile("rdtsc" : "=a"(a), "=d"(d));
return static_cast<GUIntBig>(a) | (static_cast<GUIntBig>(d) << 32);
}
static GUIntBig CPLrdtscp()
{
unsigned int a;
unsigned int d;
unsigned int unused1;
unsigned int unused2;
unsigned int unused3;
unsigned int unused4;
__asm__ volatile("rdtscp" : "=a"(a), "=d"(d));
GCC_CPUID(0, unused1, unused2, unused3, unused4);
return static_cast<GUIntBig>(a) | (static_cast<GUIntBig>(d) << 32);
}
#endif
static CPLSpinLock *CPLCreateSpinLock(); // Returned NON acquired.
static int CPLCreateOrAcquireSpinLockInternal(CPLLock **);
static int CPLAcquireSpinLock(CPLSpinLock *);
static void CPLReleaseSpinLock(CPLSpinLock *);
static void CPLDestroySpinLock(CPLSpinLock *);
#ifndef CPL_MULTIPROC_PTHREAD
#ifndef MUTEX_NONE
static CPLMutex *CPLCreateOrAcquireMasterMutex(double);
static CPLMutex *&CPLCreateOrAcquireMasterMutexInternal(double);
static CPLMutex *CPLCreateUnacquiredMutex();
#endif
#endif
// We don't want it to be publicly used since it solves rather tricky issues
// that are better to remain hidden.
void CPLFinalizeTLS();
/************************************************************************/
/* CPLMutexHolder() */
/************************************************************************/
#ifdef MUTEX_NONE
CPLMutexHolder::CPLMutexHolder(CPLMutex ** /* phMutex */,
double /* dfWaitInSeconds */,
const char * /* pszFileIn */, int /* nLineIn */,
int /* nOptions */)
{
}
#else
CPLMutexHolder::CPLMutexHolder(CPLMutex **phMutex, double dfWaitInSeconds,
const char *pszFileIn, int nLineIn, int nOptions)
: hMutex(nullptr), pszFile(pszFileIn), nLine(nLineIn)
{
if (phMutex == nullptr)
{
fprintf(stderr, "CPLMutexHolder: phMutex )) NULL !\n");
hMutex = nullptr;
return;
}
#ifdef DEBUG_MUTEX
// There is no way to use CPLDebug() here because it works with
// mutexes itself so we will fall in infinite recursion.
// fprintf() will do the job right.
fprintf(stderr, "CPLMutexHolder: Request %p for pid %ld at %d/%s.\n",
*phMutex, static_cast<long>(CPLGetPID()), nLine, pszFile);
#else
// TODO(schwehr): Find a better way to do handle this.
(void)pszFile;
(void)nLine;
#endif
if (!CPLCreateOrAcquireMutexEx(phMutex, dfWaitInSeconds, nOptions))
{
fprintf(stderr, "CPLMutexHolder: Failed to acquire mutex!\n");
hMutex = nullptr;
}
else
{
#ifdef DEBUG_MUTEX
fprintf(stderr, "CPLMutexHolder: Acquired %p for pid %ld at %d/%s.\n",
*phMutex, static_cast<long>(CPLGetPID()), nLine, pszFile);
#endif
hMutex = *phMutex;
}
}
#endif // ndef MUTEX_NONE
/************************************************************************/
/* CPLMutexHolder() */
/************************************************************************/
#ifdef MUTEX_NONE
CPLMutexHolder::CPLMutexHolder(CPLMutex * /* hMutexIn */,
double /* dfWaitInSeconds */,
const char * /* pszFileIn */, int /* nLineIn */)
{
}
#else
CPLMutexHolder::CPLMutexHolder(CPLMutex *hMutexIn, double dfWaitInSeconds,
const char *pszFileIn, int nLineIn)
: hMutex(hMutexIn), pszFile(pszFileIn), nLine(nLineIn)
{
if (hMutex != nullptr && !CPLAcquireMutex(hMutex, dfWaitInSeconds))
{
fprintf(stderr, "CPLMutexHolder: Failed to acquire mutex!\n");
hMutex = nullptr;
}
}
#endif // ndef MUTEX_NONE
/************************************************************************/
/* ~CPLMutexHolder() */
/************************************************************************/
#ifdef MUTEX_NONE
CPLMutexHolder::~CPLMutexHolder()
{
}
#else
CPLMutexHolder::~CPLMutexHolder()
{
if (hMutex != nullptr)
{
#ifdef DEBUG_MUTEX
fprintf(stderr, "~CPLMutexHolder: Release %p for pid %ld at %d/%s.\n",
hMutex, static_cast<long>(CPLGetPID()), nLine, pszFile);
#endif
CPLReleaseMutex(hMutex);
}
}
#endif // ndef MUTEX_NONE
int CPLCreateOrAcquireMutex(CPLMutex **phMutex, double dfWaitInSeconds)
{
return CPLCreateOrAcquireMutexEx(phMutex, dfWaitInSeconds,
CPL_MUTEX_RECURSIVE);
}
/************************************************************************/
/* CPLCreateOrAcquireMutex() */
/************************************************************************/
#ifndef CPL_MULTIPROC_PTHREAD
#ifndef MUTEX_NONE
CPLMutex *CPLCreateUnacquiredMutex()
{
CPLMutex *hMutex = CPLCreateMutex();
if (hMutex)
{
CPLReleaseMutex(hMutex);
}
return hMutex;
}
CPLMutex *&
CPLCreateOrAcquireMasterMutexInternal(double dfWaitInSeconds = 1000.0)
{
// The dynamic initialization of the block scope hCOAMutex
// with static storage duration is thread-safe in C++11
static CPLMutex *hCOAMutex = CPLCreateUnacquiredMutex();
// WARNING: although adding an CPLAssert(hCOAMutex); might seem logical
// here, do not enable it (see comment below). It calls CPLError that
// uses the hCOAMutex itself leading to recursive mutex acquisition
// and likely a stack overflow.
if (!hCOAMutex)
{
// Fall back to this, ironically, NOT thread-safe re-initialisation of
// hCOAMutex in case of a memory error or call to CPLCleanupMasterMutex
// sequenced in an unusual, unexpected or erroneous way.
// For example, an unusual sequence could be:
// GDALDriverManager has been instantiated,
// then OGRCleanupAll is called which calls CPLCleanupMasterMutex,
// then CPLFreeConfig is called which acquires the hCOAMutex
// that has already been released and destroyed.
hCOAMutex = CPLCreateUnacquiredMutex();
}
if (hCOAMutex)
{
CPLAcquireMutex(hCOAMutex, dfWaitInSeconds);
}
return hCOAMutex;
}
CPLMutex *CPLCreateOrAcquireMasterMutex(double dfWaitInSeconds = 1000.0)
{
CPLMutex *hCOAMutex =
CPLCreateOrAcquireMasterMutexInternal(dfWaitInSeconds);
return hCOAMutex;
}
#endif
#ifdef MUTEX_NONE
int CPLCreateOrAcquireMutexEx(CPLMutex **phMutex, double dfWaitInSeconds,
int nOptions)
{
return false;
}
#else
int CPLCreateOrAcquireMutexEx(CPLMutex **phMutex, double dfWaitInSeconds,
int nOptions)
{
bool bSuccess = false;
CPLMutex *hCOAMutex = CPLCreateOrAcquireMasterMutex(dfWaitInSeconds);
if (hCOAMutex == nullptr)
{
*phMutex = nullptr;
return FALSE;
}
if (*phMutex == nullptr)
{
*phMutex = CPLCreateMutexEx(nOptions);
bSuccess = *phMutex != nullptr;
CPLReleaseMutex(hCOAMutex);
}
else
{
CPLReleaseMutex(hCOAMutex);
bSuccess = CPL_TO_BOOL(CPLAcquireMutex(*phMutex, dfWaitInSeconds));
}
return bSuccess;
}
#endif // ndef MUTEX_NONE
/************************************************************************/
/* CPLCreateOrAcquireMutexInternal() */
/************************************************************************/
#ifdef MUTEX_NONE
static int CPLCreateOrAcquireMutexInternal(CPLLock **phLock,
double dfWaitInSeconds,
CPLLockType eType)
{
return false;
}
#else
static int CPLCreateOrAcquireMutexInternal(CPLLock **phLock,
double dfWaitInSeconds,
CPLLockType eType)
{
bool bSuccess = false;
CPLMutex *hCOAMutex = CPLCreateOrAcquireMasterMutex(dfWaitInSeconds);
if (hCOAMutex == nullptr)
{
*phLock = nullptr;
return FALSE;
}
if (*phLock == nullptr)
{
*phLock = static_cast<CPLLock *>(calloc(1, sizeof(CPLLock)));
if (*phLock)
{
(*phLock)->eType = eType;
(*phLock)->u.hMutex = CPLCreateMutexEx(
(eType == LOCK_RECURSIVE_MUTEX) ? CPL_MUTEX_RECURSIVE
: CPL_MUTEX_ADAPTIVE);
if ((*phLock)->u.hMutex == nullptr)
{
free(*phLock);
*phLock = nullptr;
}
}
bSuccess = *phLock != nullptr;
CPLReleaseMutex(hCOAMutex);
}
else
{
CPLReleaseMutex(hCOAMutex);
bSuccess =
CPL_TO_BOOL(CPLAcquireMutex((*phLock)->u.hMutex, dfWaitInSeconds));
}
return bSuccess;
}
#endif // ndef MUTEX_NONE
#endif // CPL_MULTIPROC_PTHREAD
/************************************************************************/
/* CPLCleanupMasterMutex() */
/************************************************************************/
void CPLCleanupMasterMutex()
{
#ifndef CPL_MULTIPROC_PTHREAD
#ifndef MUTEX_NONE
CPLMutex *&hCOAMutex = CPLCreateOrAcquireMasterMutexInternal();
if (hCOAMutex != nullptr)
{
CPLReleaseMutex(hCOAMutex);
CPLDestroyMutex(hCOAMutex);
hCOAMutex = nullptr;
}
#endif
#endif
}
/************************************************************************/
/* CPLCleanupTLSList() */
/* */
/* Free resources associated with a TLS vector (implementation */
/* independent). */
/************************************************************************/
static void CPLCleanupTLSList(void **papTLSList)
{
#ifdef DEBUG_VERBOSE
printf("CPLCleanupTLSList(%p)\n", papTLSList); /*ok*/
#endif
if (papTLSList == nullptr)
return;
for (int i = 0; i < CTLS_MAX; i++)
{
if (papTLSList[i] != nullptr && papTLSList[i + CTLS_MAX] != nullptr)
{
CPLTLSFreeFunc pfnFree =
reinterpret_cast<CPLTLSFreeFunc>(papTLSList[i + CTLS_MAX]);
pfnFree(papTLSList[i]);
papTLSList[i] = nullptr;
}
}
CPLFree(papTLSList);
}
#if defined(CPL_MULTIPROC_STUB)
/************************************************************************/
/* ==================================================================== */
/* CPL_MULTIPROC_STUB */
/* */
/* Stub implementation. Mutexes don't provide exclusion, file */
/* locking is achieved with extra "lock files", and thread */
/* creation doesn't work. The PID is always just one. */
/* ==================================================================== */
/************************************************************************/
/************************************************************************/
/* CPLGetNumCPUs() */
/************************************************************************/
int CPLGetNumCPUs()
{
return 1;
}
/************************************************************************/
/* CPLGetThreadingModel() */
/************************************************************************/
const char *CPLGetThreadingModel()
{
return "stub";
}
/************************************************************************/
/* CPLCreateMutex() */
/************************************************************************/
#ifdef MUTEX_NONE
CPLMutex *CPLCreateMutex()
{
return (CPLMutex *)0xdeadbeef;
}
#else
CPLMutex *CPLCreateMutex()
{
unsigned char *pabyMutex = static_cast<unsigned char *>(malloc(4));
if (pabyMutex == nullptr)
return nullptr;
pabyMutex[0] = 1;
pabyMutex[1] = 'r';
pabyMutex[2] = 'e';
pabyMutex[3] = 'd';
return (CPLMutex *)pabyMutex;
}
#endif
CPLMutex *CPLCreateMutexEx(int /*nOptions*/)
{
return CPLCreateMutex();
}
/************************************************************************/
/* CPLAcquireMutex() */
/************************************************************************/
#ifdef MUTEX_NONE
int CPLAcquireMutex(CPLMutex *hMutex, double /* dfWaitInSeconds */)
{
return TRUE;
}
#else
int CPLAcquireMutex(CPLMutex *hMutex, double /*dfWaitInSeconds*/)
{
unsigned char *pabyMutex = reinterpret_cast<unsigned char *>(hMutex);
CPLAssert(pabyMutex[1] == 'r' && pabyMutex[2] == 'e' &&
pabyMutex[3] == 'd');
pabyMutex[0] += 1;
return TRUE;
}
#endif // ! MUTEX_NONE
/************************************************************************/
/* CPLReleaseMutex() */
/************************************************************************/
#ifdef MUTEX_NONE
void CPLReleaseMutex(CPLMutex * /* hMutex */)
{
}
#else
void CPLReleaseMutex(CPLMutex *hMutex)
{
unsigned char *pabyMutex = reinterpret_cast<unsigned char *>(hMutex);
CPLAssert(pabyMutex[1] == 'r' && pabyMutex[2] == 'e' &&
pabyMutex[3] == 'd');
if (pabyMutex[0] < 1)
CPLDebug("CPLMultiProc",
"CPLReleaseMutex() called on mutex with %d as ref count!",
pabyMutex[0]);
pabyMutex[0] -= 1;
}
#endif
/************************************************************************/
/* CPLDestroyMutex() */
/************************************************************************/
#ifdef MUTEX_NONE
void CPLDestroyMutex(CPLMutex * /* hMutex */)
{
}
#else
void CPLDestroyMutex(CPLMutex *hMutex)
{
unsigned char *pabyMutex = reinterpret_cast<unsigned char *>(hMutex);
CPLAssert(pabyMutex[1] == 'r' && pabyMutex[2] == 'e' &&
pabyMutex[3] == 'd');
free(pabyMutex);
}
#endif
/************************************************************************/
/* CPLCreateCond() */
/************************************************************************/
CPLCond *CPLCreateCond()
{
return nullptr;
}
/************************************************************************/
/* CPLCondWait() */
/************************************************************************/
void CPLCondWait(CPLCond * /* hCond */, CPLMutex * /* hMutex */)
{
}
/************************************************************************/
/* CPLCondTimedWait() */
/************************************************************************/
CPLCondTimedWaitReason CPLCondTimedWait(CPLCond * /* hCond */,
CPLMutex * /* hMutex */, double)
{
return COND_TIMED_WAIT_OTHER;
}
/************************************************************************/
/* CPLCondSignal() */
/************************************************************************/
void CPLCondSignal(CPLCond * /* hCond */)
{
}
/************************************************************************/
/* CPLCondBroadcast() */
/************************************************************************/
void CPLCondBroadcast(CPLCond * /* hCond */)
{
}
/************************************************************************/
/* CPLDestroyCond() */
/************************************************************************/
void CPLDestroyCond(CPLCond * /* hCond */)
{
}
/************************************************************************/
/* CPLLockFile() */
/* */
/* Lock a file. This implementation has a terrible race */
/* condition. If we don't succeed in opening the lock file, we */
/* assume we can create one and own the target file, but other */
/* processes might easily try creating the target file at the */
/* same time, overlapping us. Death! Mayhem! The traditional */
/* solution is to use open() with _O_CREAT|_O_EXCL but this */
/* function and these arguments aren't trivially portable. */
/* Also, this still leaves a race condition on NFS drivers */
/* (apparently). */
/************************************************************************/
void *CPLLockFile(const char *pszPath, double dfWaitInSeconds)
{
/* -------------------------------------------------------------------- */
/* We use a lock file with a name derived from the file we want */
/* to lock to represent the file being locked. Note that for */
/* the stub implementation the target file does not even need */
/* to exist to be locked. */
/* -------------------------------------------------------------------- */
char *pszLockFilename =
static_cast<char *>(CPLMalloc(strlen(pszPath) + 30));
snprintf(pszLockFilename, strlen(pszPath) + 30, "%s.lock", pszPath);
FILE *fpLock = fopen(pszLockFilename, "r");
while (fpLock != nullptr && dfWaitInSeconds > 0.0)
{
fclose(fpLock);
CPLSleep(std::min(dfWaitInSeconds, 0.5));
dfWaitInSeconds -= 0.5;
fpLock = fopen(pszLockFilename, "r");
}
if (fpLock != nullptr)
{
fclose(fpLock);
CPLFree(pszLockFilename);
return nullptr;
}
fpLock = fopen(pszLockFilename, "w");
if (fpLock == nullptr)
{
CPLFree(pszLockFilename);
return nullptr;
}
fwrite("held\n", 1, 5, fpLock);
fclose(fpLock);
return pszLockFilename;
}
/************************************************************************/
/* CPLUnlockFile() */
/************************************************************************/
void CPLUnlockFile(void *hLock)
{
char *pszLockFilename = static_cast<char *>(hLock);
if (hLock == nullptr)
return;
VSIUnlink(pszLockFilename);
CPLFree(pszLockFilename);
}
/************************************************************************/
/* CPLGetPID() */
/************************************************************************/
GIntBig CPLGetPID()
{
return 1;
}
/************************************************************************/
/* CPLCreateThread(); */
/************************************************************************/
int CPLCreateThread(CPLThreadFunc /* pfnMain */, void * /* pArg */)
{
CPLDebug("CPLCreateThread", "Fails to dummy implementation");
return -1;
}
/************************************************************************/
/* CPLCreateJoinableThread() */
/************************************************************************/
CPLJoinableThread *CPLCreateJoinableThread(CPLThreadFunc /* pfnMain */,
void * /* pThreadArg */)
{
CPLDebug("CPLCreateJoinableThread", "Fails to dummy implementation");
return nullptr;
}
/************************************************************************/
/* CPLJoinThread() */
/************************************************************************/
void CPLJoinThread(CPLJoinableThread * /* hJoinableThread */)
{
}
/************************************************************************/
/* CPLSleep() */
/************************************************************************/
void CPLSleep(double dfWaitInSeconds)
{
time_t ltime;
time(<ime);
const time_t ttime = ltime + static_cast<int>(dfWaitInSeconds + 0.5);
for (; ltime < ttime; time(<ime))
{
// Currently we just busy wait. Perhaps we could at least block on io?
}
}
/************************************************************************/
/* CPLGetTLSList() */
/************************************************************************/
static void **papTLSList = nullptr;
static void **CPLGetTLSList(int *pbMemoryErrorOccurred)
{
if (pbMemoryErrorOccurred)
*pbMemoryErrorOccurred = FALSE;
if (papTLSList == nullptr)
{
papTLSList =
static_cast<void **>(VSICalloc(sizeof(void *), CTLS_MAX * 2));
if (papTLSList == nullptr)
{
if (pbMemoryErrorOccurred)
{
*pbMemoryErrorOccurred = TRUE;
fprintf(stderr,
"CPLGetTLSList() failed to allocate TLS list!\n");
return nullptr;
}
CPLEmergencyError("CPLGetTLSList() failed to allocate TLS list!");
}
}
return papTLSList;
}
/************************************************************************/
/* CPLFinalizeTLS() */
/************************************************************************/
void CPLFinalizeTLS()
{
CPLCleanupTLS();
}
/************************************************************************/
/* CPLCleanupTLS() */
/************************************************************************/
void CPLCleanupTLS()
{
CPLCleanupTLSList(papTLSList);
papTLSList = nullptr;
}
// endif CPL_MULTIPROC_STUB
#elif defined(CPL_MULTIPROC_WIN32)
/************************************************************************/
/* ==================================================================== */
/* CPL_MULTIPROC_WIN32 */
/* */
/* WIN32 Implementation of multiprocessing functions. */
/* ==================================================================== */
/************************************************************************/
/* InitializeCriticalSectionAndSpinCount requires _WIN32_WINNT >= 0x403 */
#undef _WIN32_WINNT
#define _WIN32_WINNT 0x0500
#include <windows.h>
/************************************************************************/
/* CPLGetNumCPUs() */
/************************************************************************/
int CPLGetNumCPUs()
{
SYSTEM_INFO info;
GetSystemInfo(&info);
const DWORD dwNum = info.dwNumberOfProcessors;
if (dwNum < 1)
return 1;
return static_cast<int>(dwNum);
}
/************************************************************************/
/* CPLGetThreadingModel() */
/************************************************************************/
const char *CPLGetThreadingModel()
{
return "win32";
}
/************************************************************************/
/* CPLCreateMutex() */
/************************************************************************/
CPLMutex *CPLCreateMutex()
{
#ifdef USE_WIN32_MUTEX
HANDLE hMutex = CreateMutex(nullptr, TRUE, nullptr);
return (CPLMutex *)hMutex;
#else
// Do not use CPLMalloc() since its debugging infrastructure
// can call the CPL*Mutex functions.
CRITICAL_SECTION *pcs =
static_cast<CRITICAL_SECTION *>(malloc(sizeof(*pcs)));
if (pcs)
{
InitializeCriticalSectionAndSpinCount(pcs, 4000);
EnterCriticalSection(pcs);
}
return reinterpret_cast<CPLMutex *>(pcs);
#endif
}
CPLMutex *CPLCreateMutexEx(int /* nOptions */)
{
return CPLCreateMutex();
}
/************************************************************************/
/* CPLAcquireMutex() */
/************************************************************************/
int CPLAcquireMutex(CPLMutex *hMutexIn, double dfWaitInSeconds)
{
#ifdef USE_WIN32_MUTEX
HANDLE hMutex = (HANDLE)hMutexIn;
const DWORD hr =
WaitForSingleObject(hMutex, static_cast<int>(dfWaitInSeconds * 1000));
return hr != WAIT_TIMEOUT;
#else
CRITICAL_SECTION *pcs = reinterpret_cast<CRITICAL_SECTION *>(hMutexIn);
BOOL ret;
if (dfWaitInSeconds >= 1000.0)
{
// We assume this is the synonymous for infinite, so it is more
// efficient to use EnterCriticalSection() directly
EnterCriticalSection(pcs);
ret = TRUE;
}
else
{
while ((ret = TryEnterCriticalSection(pcs)) == 0 &&
dfWaitInSeconds > 0.0)
{
CPLSleep(std::min(dfWaitInSeconds, 0.01));
dfWaitInSeconds -= 0.01;
}
}
return ret;
#endif
}
/************************************************************************/
/* CPLReleaseMutex() */
/************************************************************************/
void CPLReleaseMutex(CPLMutex *hMutexIn)
{
#ifdef USE_WIN32_MUTEX
HANDLE hMutex = (HANDLE)hMutexIn;
ReleaseMutex(hMutex);
#else
CRITICAL_SECTION *pcs = reinterpret_cast<CRITICAL_SECTION *>(hMutexIn);
LeaveCriticalSection(pcs);
#endif
}
/************************************************************************/
/* CPLDestroyMutex() */
/************************************************************************/
void CPLDestroyMutex(CPLMutex *hMutexIn)
{
#ifdef USE_WIN32_MUTEX
HANDLE hMutex = (HANDLE)hMutexIn;
CloseHandle(hMutex);
#else
CRITICAL_SECTION *pcs = reinterpret_cast<CRITICAL_SECTION *>(hMutexIn);
DeleteCriticalSection(pcs);
free(pcs);
#endif
}
/************************************************************************/
/* CPLCreateCond() */
/************************************************************************/
struct _WaiterItem
{
HANDLE hEvent;
struct _WaiterItem *psNext;
};
typedef struct _WaiterItem WaiterItem;
typedef struct
{
CPLMutex *hInternalMutex;
WaiterItem *psWaiterList;
} Win32Cond;
CPLCond *CPLCreateCond()
{
Win32Cond *psCond = static_cast<Win32Cond *>(malloc(sizeof(Win32Cond)));
if (psCond == nullptr)
return nullptr;
psCond->hInternalMutex = CPLCreateMutex();