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Disable WinXP mutex emulation when _WIN32_WINNT >= 0x0600

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This commit is contained in:
rdb 2019-02-09 22:54:17 +01:00
parent 89392f0e2d
commit ab569916b1
1 changed files with 32 additions and 4 deletions
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36
dtool/src/dtoolbase/mutexWin32Impl.cxx
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@ -17,13 +17,18 @@
#include "mutexWin32Impl.h"
// The number of spins to do before suspending the thread.
static const unsigned int spin_count = 4000;
// Only compile the below nonsense if we're not compiling for a Vista minimum.
#if _WIN32_WINNT < 0x0600
// If this is true, we will use SRWLock on Windows Vista and above instead of
// our own implementation.
static const bool prefer_srwlock = true;
// These configure our own Windows XP implementation.
static const uintptr_t lock_bit = 0x40000000;
static const unsigned int spin_count = 4000;
// This gets set to spin_count if we are on a multi-core system.
static unsigned int effective_spin_count = 0;
@ -262,6 +267,8 @@ cvar_notify_all_xp(volatile PVOID *cvar) {
}
}
#endif // _WIN32_WINNT < 0x0600
/**
* This is put initially in the _lock slot; it makes sure that the lock
* functions get initialized the first time someone tries to grab a lock.
@ -282,17 +289,29 @@ try_lock_initially(volatile PVOID *lock) {
return MutexWin32Impl::_funcs._try_lock(lock);
}
#ifndef NDEBUG
/**
* This gets put initially in the _unlock slot and should never be called,
* since the initial lock/try_lock implementation will replace the pointers.
*/
void __stdcall MutexWin32Impl::
unlock_initially(volatile PVOID *) {
#if !defined(NDEBUG) || defined(DEBUG_THREADS)
std::cerr << "Attempt to release a mutex at static init time before acquiring it!\n";
assert(false);
}
#endif
}
/**
* Same as above for condition variables.
*/
static BOOL __stdcall
cvar_wait_initially(volatile PVOID *cvar, volatile PVOID *lock, DWORD timeout, ULONG) {
#if !defined(NDEBUG) || defined(DEBUG_THREADS)
std::cerr << "Attempt to wait for condition variable at static init time before acquiring mutex!\n";
assert(false);
#endif
return FALSE;
}
/**
* Does nothing.
@ -312,7 +331,7 @@ MutexWin32Impl::LockFunctions MutexWin32Impl::_funcs = {
&noop,
#endif
&cvar_wait_xp,
&cvar_wait_initially,
#ifndef NDEBUG
&MutexWin32Impl::unlock_initially,
&MutexWin32Impl::unlock_initially,
@ -332,6 +351,14 @@ init_lock_funcs() {
return;
}
#if _WIN32_WINNT >= 0x0600
_funcs._lock = (LockFunc)AcquireSRWLockExclusive;
_funcs._try_lock = (TryLockFunc)TryAcquireSRWLockExclusive;
_funcs._unlock = (LockFunc)ReleaseSRWLockExclusive;
_funcs._cvar_wait = (CondWaitFunc)SleepConditionVariableSRW;
_funcs._cvar_notify_one = (LockFunc)WakeConditionVariable;
_funcs._cvar_notify_all = (LockFunc)WakeAllConditionVariable;
#else
// We don't need to be very thread safe here. This can only ever be called
// at static init time, when there is still only one thread.
if (prefer_srwlock) {
@ -370,6 +397,7 @@ init_lock_funcs() {
} else {
effective_spin_count = 0;
}
#endif // _WIN32_WINNT < 0x0600
}
/**