Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#ifndef THREAD_WIN32_H_INCLUDED
#define THREAD_WIN32_H_INCLUDED
-/// STL thread library uded by gcc and mingw compilers is implemented above
-/// POSIX pthread. Unfortunatly this yields to a much slower speed (about 30%)
-/// than the native Win32 calls. So use our own implementation that relies on
-/// the Windows specific low level calls.
+/// STL thread library used by mingw and gcc when cross compiling for Windows
+/// relies on libwinpthread. Currently libwinpthread implements mutexes directly
+/// on top of Windows semaphores. Semaphores, being kernel objects, require kernel
+/// mode transition in order to lock or unlock, which is very slow compared to
+/// interlocked operations (about 30% slower on bench test). To work around this
+/// issue, we define our wrappers to the low level Win32 calls. We use critical
+/// sections to support Windows XP and older versions. Unfortunately, cond_wait()
+/// is racy between unlock() and WaitForSingleObject() but they have the same
+/// speed performance as the SRW locks.
+
+#include <condition_variable>
+#include <mutex>
#if defined(_WIN32) && !defined(_MSC_VER)
#ifndef NOMINMAX
-# define NOMINMAX // disable macros min() and max()
+# define NOMINMAX // Disable macros min() and max()
#endif
#define WIN32_LEAN_AND_MEAN
#undef WIN32_LEAN_AND_MEAN
#undef NOMINMAX
-// We use critical sections on Windows to support Windows XP and older versions.
-// Unfortunately, cond_wait() is racy between lock_release() and WaitForSingleObject()
-// but apart from this they have the same speed performance of SRW locks.
-typedef CRITICAL_SECTION Lock;
-typedef HANDLE WaitCondition;
-typedef HANDLE NativeHandle;
-
-// On Windows 95 and 98 parameter lpThreadId may not be null
-inline DWORD* dwWin9xKludge() { static DWORD dw; return &dw; }
-
-# define lock_init(x) InitializeCriticalSection(&(x))
-# define lock_grab(x) EnterCriticalSection(&(x))
-# define lock_release(x) LeaveCriticalSection(&(x))
-# define lock_destroy(x) DeleteCriticalSection(&(x))
-# define cond_init(x) { x = CreateEvent(0, FALSE, FALSE, 0); }
-# define cond_destroy(x) CloseHandle(x)
-# define cond_signal(x) SetEvent(x)
-# define cond_wait(x,y) { lock_release(y); WaitForSingleObject(x, INFINITE); lock_grab(y); }
-# define cond_timedwait(x,y,z) { lock_release(y); WaitForSingleObject(x,z); lock_grab(y); }
-
/// Mutex and ConditionVariable struct are wrappers of the low level locking
/// machinery and are modeled after the corresponding C++11 classes.
struct Mutex {
- Mutex() { lock_init(l); }
- ~Mutex() { lock_destroy(l); }
-
- void lock() { lock_grab(l); }
- void unlock() { lock_release(l); }
+ Mutex() { InitializeCriticalSection(&cs); }
+ ~Mutex() { DeleteCriticalSection(&cs); }
+ void lock() { EnterCriticalSection(&cs); }
+ void unlock() { LeaveCriticalSection(&cs); }
private:
- friend struct ConditionVariable;
-
- Lock l;
+ CRITICAL_SECTION cs;
};
-struct ConditionVariable {
- ConditionVariable() { cond_init(c); }
- ~ConditionVariable() { cond_destroy(c); }
-
- void notify_one() { cond_signal(c); }
- void wait(std::unique_lock<Mutex>& lk) { cond_wait(c, lk.mutex()->l); }
-
- template<class Predicate>
- void wait(std::unique_lock<Mutex>& lk, Predicate p) { while (!p()) this->wait(lk); }
-
- void wait_for(std::unique_lock<Mutex>& lk, const std::chrono::milliseconds& ms) {
- cond_timedwait(c, lk.mutex()->l, ms.count());
- }
-
-private:
- WaitCondition c;
-};
+typedef std::condition_variable_any ConditionVariable;
#else // Default case: use STL classes