threads in MinGW

mingw.mutex.h

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+/**
+* @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);
+        throw system_error(make_error_code(errc::resource_deadlock_would_occur));
+    }
+    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.
+#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))
+        {
+            throw std::system_error(GetLastError(), std::system_category());
+        }
+    }
+    void unlock()
+    {
+        if (!ReleaseMutex(mHandle))
+            throw std::system_error(GetLastError(), std::system_category());
+    }
+    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(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_acquire))
+        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)
+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