/**
* @file mingw.mutex.h
* @brief std::mutex et al implementation for MinGW
** (c) 2013-2016 by Mega Limited, Auckland, New Zealand
* @author Alexander Vassilev
*
* @copyright Simplified (2-clause) BSD License.
* You should have received a copy of the license along with this
* program.
*
* This code is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* @note
* This file may become part of the mingw-w64 runtime package. If/when this happens,
* the appropriate license will be added, i.e. this code will become dual-licensed,
* and the current BSD 2-clause license will stay.
*/
#ifndef WIN32STDMUTEX_H
#define WIN32STDMUTEX_H
#if !defined(__cplusplus) || (__cplusplus < 201103L)
#error A C++11 compiler is required!
#endif
// Recursion checks on non-recursive locks have some performance penalty, and
// the C++ standard does not mandate them. The user might want to explicitly
// enable or disable such checks. If the user has no preference, enable such
// checks in debug builds, but not in release builds.
#ifdef STDMUTEX_RECURSION_CHECKS
#elif defined(NDEBUG)
#define STDMUTEX_RECURSION_CHECKS 0
#else
#define STDMUTEX_RECURSION_CHECKS 1
#endif
#include <chrono>
#include <system_error>
#include <atomic>
#include <mutex> //need for call_once()
#if STDMUTEX_RECURSION_CHECKS || !defined(NDEBUG)
#include <cstdio>
#endif
#include <sdkddkver.h> // Detect Windows version.
#if (defined(__MINGW32__) && !defined(__MINGW64_VERSION_MAJOR))
#pragma message "The Windows API that MinGW-w32 provides is not fully compatible\
with Microsoft's API. We'll try to work around this, but we can make no\
guarantees. This problem does not exist in MinGW-w64."
#include <windows.h> // No further granularity can be expected.
#else
#if STDMUTEX_RECURSION_CHECKS
#include <processthreadsapi.h> // For GetCurrentThreadId
#endif
#include <synchapi.h> // For InitializeCriticalSection, etc.
#include <errhandlingapi.h> // For GetLastError
#include <handleapi.h>
#endif
// Need for the implementation of invoke
#include "mingw.invoke.h"
#if !defined(_WIN32_WINNT) || (_WIN32_WINNT < 0x0501)
#error To use the MinGW-std-threads library, you will need to define the macro _WIN32_WINNT to be 0x0501 (Windows XP) or higher.
#endif
namespace mingw_stdthread
{
// The _NonRecursive class has mechanisms that do not play nice with direct
// manipulation of the native handle. This forward declaration is part of
// a friend class declaration.
#if STDMUTEX_RECURSION_CHECKS
namespace vista
{
class condition_variable;
}
#endif
// To make this namespace equivalent to the thread-related subset of std,
// pull in the classes and class templates supplied by std but not by this
// implementation.
using std::lock_guard;
using std::unique_lock;
using std::adopt_lock_t;
using std::defer_lock_t;
using std::try_to_lock_t;
using std::adopt_lock;
using std::defer_lock;
using std::try_to_lock;
class recursive_mutex
{
CRITICAL_SECTION mHandle;
public:
typedef LPCRITICAL_SECTION native_handle_type;
native_handle_type native_handle() {return &mHandle;}
recursive_mutex() noexcept : mHandle()
{
InitializeCriticalSection(&mHandle);
}
recursive_mutex (const recursive_mutex&) = delete;
recursive_mutex& operator=(const recursive_mutex&) = delete;
~recursive_mutex() noexcept
{
DeleteCriticalSection(&mHandle);
}
void lock()
{
EnterCriticalSection(&mHandle);
}
void unlock()
{
LeaveCriticalSection(&mHandle);
}
bool try_lock()
{
return (TryEnterCriticalSection(&mHandle)!=0);
}
};
#if STDMUTEX_RECURSION_CHECKS
struct _OwnerThread
{
// If this is to be read before locking, then the owner-thread variable must
// be atomic to prevent a torn read from spuriously causing errors.
std::atomic<DWORD> mOwnerThread;
constexpr _OwnerThread () noexcept : mOwnerThread(0) {}
static void on_deadlock (void)
{
using namespace std;
fprintf(stderr, "FATAL: Recursive locking of non-recursive mutex\
detected. Throwing system exception\n");
fflush(stderr);
__builtin_trap();
}
DWORD checkOwnerBeforeLock() const
{
DWORD self = GetCurrentThreadId();
if (mOwnerThread.load(std::memory_order_relaxed) == self)
on_deadlock();
return self;
}
void setOwnerAfterLock(DWORD id)
{
mOwnerThread.store(id, std::memory_order_relaxed);
}
void checkSetOwnerBeforeUnlock()
{
DWORD self = GetCurrentThreadId();
if (mOwnerThread.load(std::memory_order_relaxed) != self)
on_deadlock();
mOwnerThread.store(0, std::memory_order_relaxed);
}
};
#endif
// Though the Slim Reader-Writer (SRW) locks used here are not complete until
// Windows 7, implementing partial functionality in Vista will simplify the
// interaction with condition variables.
//Define SRWLOCK_INIT.
#if !defined(SRWLOCK_INIT)
#pragma message "SRWLOCK_INIT macro is not defined. Defining automatically."
#define SRWLOCK_INIT {0}
#endif
#if defined(_WIN32) && (WINVER >= _WIN32_WINNT_VISTA)
namespace windows7
{
class mutex
{
SRWLOCK mHandle;
// Track locking thread for error checking.
#if STDMUTEX_RECURSION_CHECKS
friend class vista::condition_variable;
_OwnerThread mOwnerThread {};
#endif
public:
typedef PSRWLOCK native_handle_type;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wzero-as-null-pointer-constant"
constexpr mutex () noexcept : mHandle(SRWLOCK_INIT) { }
#pragma GCC diagnostic pop
mutex (const mutex&) = delete;
mutex & operator= (const mutex&) = delete;
void lock (void)
{
// Note: Undefined behavior if called recursively.
#if STDMUTEX_RECURSION_CHECKS
DWORD self = mOwnerThread.checkOwnerBeforeLock();
#endif
AcquireSRWLockExclusive(&mHandle);
#if STDMUTEX_RECURSION_CHECKS
mOwnerThread.setOwnerAfterLock(self);
#endif
}
void unlock (void)
{
#if STDMUTEX_RECURSION_CHECKS
mOwnerThread.checkSetOwnerBeforeUnlock();
#endif
ReleaseSRWLockExclusive(&mHandle);
}
// TryAcquireSRW functions are a Windows 7 feature.
#if (WINVER >= _WIN32_WINNT_WIN7)
bool try_lock (void)
{
#if STDMUTEX_RECURSION_CHECKS
DWORD self = mOwnerThread.checkOwnerBeforeLock();
#endif
BOOL ret = TryAcquireSRWLockExclusive(&mHandle);
#if STDMUTEX_RECURSION_CHECKS
if (ret)
mOwnerThread.setOwnerAfterLock(self);
#endif
return ret;
}
#endif
native_handle_type native_handle (void)
{
return &mHandle;
}
};
} // Namespace windows7
#endif // Compiling for Vista
namespace xp
{
class mutex
{
CRITICAL_SECTION mHandle;
std::atomic_uchar mState;
// Track locking thread for error checking.
#if STDMUTEX_RECURSION_CHECKS
friend class vista::condition_variable;
_OwnerThread mOwnerThread {};
#endif
public:
typedef PCRITICAL_SECTION native_handle_type;
constexpr mutex () noexcept : mHandle(), mState(2) { }
mutex (const mutex&) = delete;
mutex & operator= (const mutex&) = delete;
~mutex() noexcept
{
// Undefined behavior if the mutex is held (locked) by any thread.
// Undefined behavior if a thread terminates while holding ownership of the
// mutex.
DeleteCriticalSection(&mHandle);
}
void lock (void)
{
unsigned char state = mState.load(std::memory_order_acquire);
while (state) {
if ((state == 2) && mState.compare_exchange_weak(state, 1, std::memory_order_acquire))
{
InitializeCriticalSection(&mHandle);
mState.store(0, std::memory_order_release);
break;
}
if (state == 1)
{
Sleep(0);
state = mState.load(std::memory_order_acquire);
}
}
#if STDMUTEX_RECURSION_CHECKS
DWORD self = mOwnerThread.checkOwnerBeforeLock();
#endif
EnterCriticalSection(&mHandle);
#if STDMUTEX_RECURSION_CHECKS
mOwnerThread.setOwnerAfterLock(self);
#endif
}
void unlock (void)
{
#if STDMUTEX_RECURSION_CHECKS
mOwnerThread.checkSetOwnerBeforeUnlock();
#endif
LeaveCriticalSection(&mHandle);
}
bool try_lock (void)
{
unsigned char state = mState.load(std::memory_order_acquire);
if ((state == 2) && mState.compare_exchange_strong(state, 1, std::memory_order_acquire))
{
InitializeCriticalSection(&mHandle);
mState.store(0, std::memory_order_release);
}
if (state == 1)
return false;
#if STDMUTEX_RECURSION_CHECKS
DWORD self = mOwnerThread.checkOwnerBeforeLock();
#endif
BOOL ret = TryEnterCriticalSection(&mHandle);
#if STDMUTEX_RECURSION_CHECKS
if (ret)
mOwnerThread.setOwnerAfterLock(self);
#endif
return ret;
}
native_handle_type native_handle (void)
{
return &mHandle;
}
};
} // Namespace "xp"
#if (WINVER >= _WIN32_WINNT_WIN7)
using windows7::mutex;
#else
using xp::mutex;
#endif
class recursive_timed_mutex
{
static constexpr DWORD kWaitAbandoned = 0x00000080l;
static constexpr DWORD kWaitObject0 = 0x00000000l;
static constexpr DWORD kInfinite = 0xffffffffl;
inline bool try_lock_internal (DWORD ms) noexcept
{
DWORD ret = WaitForSingleObject(mHandle, ms);
#ifndef NDEBUG
if (ret == kWaitAbandoned)
{
using namespace std;
fprintf(stderr, "FATAL: Thread terminated while holding a mutex.");
terminate();
}
#endif
return (ret == kWaitObject0) || (ret == kWaitAbandoned);
}
protected:
HANDLE mHandle;
// Track locking thread for error checking of non-recursive timed_mutex. For
// standard compliance, this must be defined in same class and at the same
// access-control level as every other variable in the timed_mutex.
#if STDMUTEX_RECURSION_CHECKS
friend class vista::condition_variable;
_OwnerThread mOwnerThread {};
#endif
public:
typedef HANDLE native_handle_type;
native_handle_type native_handle() const {return mHandle;}
recursive_timed_mutex(const recursive_timed_mutex&) = delete;
recursive_timed_mutex& operator=(const recursive_timed_mutex&) = delete;
recursive_timed_mutex(): mHandle(CreateMutex(NULL, FALSE, NULL)) {}
~recursive_timed_mutex()
{
CloseHandle(mHandle);
}
void lock()
{
DWORD ret = WaitForSingleObject(mHandle, kInfinite);
// If (ret == WAIT_ABANDONED), then the thread that held ownership was
// terminated. Behavior is undefined, but Windows will pass ownership to this
// thread.
#ifndef NDEBUG
if (ret == kWaitAbandoned)
{
using namespace std;
fprintf(stderr, "FATAL: Thread terminated while holding a mutex.");
terminate();
}
#endif
if ((ret != kWaitObject0) && (ret != kWaitAbandoned))
{
__builtin_trap();
}
}
void unlock()
{
if (!ReleaseMutex(mHandle))
__builtin_trap();
}
bool try_lock()
{
return try_lock_internal(0);
}
template <class Rep, class Period>
bool try_lock_for(const std::chrono::duration<Rep,Period>& dur)
{
using namespace std::chrono;
auto timeout = duration_cast<milliseconds>(dur).count();
while (timeout > 0)
{
constexpr auto kMaxStep = static_cast<decltype(timeout)>(kInfinite-1);
auto step = (timeout < kMaxStep) ? timeout : kMaxStep;
if (try_lock_internal(static_cast<DWORD>(step)))
return true;
timeout -= step;
}
return false;
}
template <class Clock, class Duration>
bool try_lock_until(const std::chrono::time_point<Clock,Duration>& timeout_time)
{
return try_lock_for(timeout_time - Clock::now());
}
};
// Override if, and only if, it is necessary for error-checking.
#if STDMUTEX_RECURSION_CHECKS
class timed_mutex: recursive_timed_mutex
{
public:
timed_mutex() = default;
timed_mutex(const timed_mutex&) = delete;
timed_mutex& operator=(const timed_mutex&) = delete;
void lock()
{
DWORD self = mOwnerThread.checkOwnerBeforeLock();
recursive_timed_mutex::lock();
mOwnerThread.setOwnerAfterLock(self);
}
void unlock()
{
mOwnerThread.checkSetOwnerBeforeUnlock();
recursive_timed_mutex::unlock();
}
template <class Rep, class Period>
bool try_lock_for(const std::chrono::duration<Rep,Period>& dur)
{
DWORD self = mOwnerThread.checkOwnerBeforeLock();
bool ret = recursive_timed_mutex::try_lock_for(dur);
if (ret)
mOwnerThread.setOwnerAfterLock(self);
return ret;
}
template <class Clock, class Duration>
bool try_lock_until(const std::chrono::time_point<Clock,Duration>& timeout_time)
{
return try_lock_for(timeout_time - Clock::now());
}
bool try_lock ()
{
return try_lock_for(std::chrono::milliseconds(0));
}
};
#else
typedef recursive_timed_mutex timed_mutex;
#endif
class once_flag
{
// When available, the SRW-based mutexes should be faster than the
// CriticalSection-based mutexes. Only try_lock will be unavailable in Vista,
// and try_lock is not used by once_flag.
#if (_WIN32_WINNT == _WIN32_WINNT_VISTA)
windows7::mutex mMutex;
#else
mutex mMutex;
#endif
std::atomic_bool mHasRun;
once_flag(const once_flag&) = delete;
once_flag& operator=(const once_flag&) = delete;
template<class Callable, class... Args>
friend void call_once(once_flag& once, Callable&& f, Args&&... args);
public:
constexpr once_flag() noexcept: mMutex(), mHasRun(false) {}
};
template<class Callable, class... Args>
void call_once(once_flag& flag, Callable&& func, Args&&... args)
{
if (flag.mHasRun.load(std::memory_order_acquire))
return;
lock_guard<decltype(flag.mMutex)> lock(flag.mMutex);
if (flag.mHasRun.load(std::memory_order_relaxed))
return;
detail::invoke(std::forward<Callable>(func),std::forward<Args>(args)...);
flag.mHasRun.store(true, std::memory_order_release);
}
} // Namespace mingw_stdthread
// Push objects into std, but only if they are not already there.
namespace std
{
// Because of quirks of the compiler, the common "using namespace std;"
// directive would flatten the namespaces and introduce ambiguity where there
// was none. Direct specification (std::), however, would be unaffected.
// Take the safe option, and include only in the presence of MinGW's win32
// implementation.
#if defined(__MINGW32__ ) && !defined(_GLIBCXX_HAS_GTHREADS) && !defined(__clang__)
using mingw_stdthread::recursive_mutex;
using mingw_stdthread::mutex;
using mingw_stdthread::recursive_timed_mutex;
using mingw_stdthread::timed_mutex;
using mingw_stdthread::once_flag;
using mingw_stdthread::call_once;
#elif !defined(MINGW_STDTHREAD_REDUNDANCY_WARNING) // Skip repetition
#define MINGW_STDTHREAD_REDUNDANCY_WARNING
#pragma message "This version of MinGW seems to include a win32 port of\
pthreads, and probably already has C++11 std threading classes implemented,\
based on pthreads. These classes, found in namespace std, are not overridden\
by the mingw-std-thread library. If you would still like to use this\
implementation (as it is more lightweight), use the classes provided in\
namespace mingw_stdthread."
#endif
}
#endif // WIN32STDMUTEX_H
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