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wine/dlls/ntdll/sync.c
Zebediah Figura f3e9498740 ntdll: Reimplement SRW locks on top of Win32 futexes. 
Signed-off-by: Zebediah Figura <zfigura@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
2021-11-18 11:09:25 +01:00

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/*
* Process synchronisation
*
* Copyright 1996, 1997, 1998 Marcus Meissner
* Copyright 1997, 1998, 1999 Alexandre Julliard
* Copyright 1999, 2000 Juergen Schmied
* Copyright 2003 Eric Pouech
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
#include <limits.h>
#include <string.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "ntstatus.h"
#define WIN32_NO_STATUS
#define NONAMELESSUNION
#include "windef.h"
#include "winternl.h"
#include "wine/debug.h"
#include "wine/list.h"
#include "ntdll_misc.h"
WINE_DEFAULT_DEBUG_CHANNEL(sync);
WINE_DECLARE_DEBUG_CHANNEL(relay);
static const char *debugstr_timeout( const LARGE_INTEGER *timeout )
{
if (!timeout) return "(infinite)";
return wine_dbgstr_longlong( timeout->QuadPart );
}
/******************************************************************
* RtlRunOnceInitialize (NTDLL.@)
*/
void WINAPI RtlRunOnceInitialize( RTL_RUN_ONCE *once )
{
once->Ptr = NULL;
}
/******************************************************************
* RtlRunOnceBeginInitialize (NTDLL.@)
*/
DWORD WINAPI RtlRunOnceBeginInitialize( RTL_RUN_ONCE *once, ULONG flags, void **context )
{
if (flags & RTL_RUN_ONCE_CHECK_ONLY)
{
ULONG_PTR val = (ULONG_PTR)once->Ptr;
if (flags & RTL_RUN_ONCE_ASYNC) return STATUS_INVALID_PARAMETER;
if ((val & 3) != 2) return STATUS_UNSUCCESSFUL;
if (context) *context = (void *)(val & ~3);
return STATUS_SUCCESS;
}
for (;;)
{
ULONG_PTR next, val = (ULONG_PTR)once->Ptr;
switch (val & 3)
{
case 0: /* first time */
if (!InterlockedCompareExchangePointer( &once->Ptr,
(flags & RTL_RUN_ONCE_ASYNC) ? (void *)3 : (void *)1, 0 ))
return STATUS_PENDING;
break;
case 1: /* in progress, wait */
if (flags & RTL_RUN_ONCE_ASYNC) return STATUS_INVALID_PARAMETER;
next = val & ~3;
if (InterlockedCompareExchangePointer( &once->Ptr, (void *)((ULONG_PTR)&next | 1),
(void *)val ) == (void *)val)
NtWaitForKeyedEvent( 0, &next, FALSE, NULL );
break;
case 2: /* done */
if (context) *context = (void *)(val & ~3);
return STATUS_SUCCESS;
case 3: /* in progress, async */
if (!(flags & RTL_RUN_ONCE_ASYNC)) return STATUS_INVALID_PARAMETER;
return STATUS_PENDING;
}
}
}
/******************************************************************
* RtlRunOnceComplete (NTDLL.@)
*/
DWORD WINAPI RtlRunOnceComplete( RTL_RUN_ONCE *once, ULONG flags, void *context )
{
if ((ULONG_PTR)context & 3) return STATUS_INVALID_PARAMETER;
if (flags & RTL_RUN_ONCE_INIT_FAILED)
{
if (context) return STATUS_INVALID_PARAMETER;
if (flags & RTL_RUN_ONCE_ASYNC) return STATUS_INVALID_PARAMETER;
}
else context = (void *)((ULONG_PTR)context | 2);
for (;;)
{
ULONG_PTR val = (ULONG_PTR)once->Ptr;
switch (val & 3)
{
case 1: /* in progress */
if (InterlockedCompareExchangePointer( &once->Ptr, context, (void *)val ) != (void *)val) break;
val &= ~3;
while (val)
{
ULONG_PTR next = *(ULONG_PTR *)val;
NtReleaseKeyedEvent( 0, (void *)val, FALSE, NULL );
val = next;
}
return STATUS_SUCCESS;
case 3: /* in progress, async */
if (!(flags & RTL_RUN_ONCE_ASYNC)) return STATUS_INVALID_PARAMETER;
if (InterlockedCompareExchangePointer( &once->Ptr, context, (void *)val ) != (void *)val) break;
return STATUS_SUCCESS;
default:
return STATUS_UNSUCCESSFUL;
}
}
}
/***********************************************************************
* Critical sections
***********************************************************************/
static void *no_debug_info_marker = (void *)(ULONG_PTR)-1;
static BOOL crit_section_has_debuginfo( const RTL_CRITICAL_SECTION *crit )
{
return crit->DebugInfo != NULL && crit->DebugInfo != no_debug_info_marker;
}
static inline HANDLE get_semaphore( RTL_CRITICAL_SECTION *crit )
{
HANDLE ret = crit->LockSemaphore;
if (!ret)
{
HANDLE sem;
if (NtCreateSemaphore( &sem, SEMAPHORE_ALL_ACCESS, NULL, 0, 1 )) return 0;
if (!(ret = InterlockedCompareExchangePointer( &crit->LockSemaphore, sem, 0 )))
ret = sem;
else
NtClose(sem); /* somebody beat us to it */
}
return ret;
}
static inline NTSTATUS wait_semaphore( RTL_CRITICAL_SECTION *crit, int timeout )
{
LARGE_INTEGER time = {.QuadPart = timeout * (LONGLONG)-10000000};
/* debug info is cleared by MakeCriticalSectionGlobal */
if (!crit_section_has_debuginfo( crit ))
{
HANDLE sem = get_semaphore( crit );
return NtWaitForSingleObject( sem, FALSE, &time );
}
else
{
int *lock = (int *)&crit->LockSemaphore;
while (!InterlockedCompareExchange( lock, 0, 1 ))
{
static const int zero;
/* this may wait longer than specified in case of multiple wake-ups */
if (RtlWaitOnAddress( lock, &zero, sizeof(int), &time ) == STATUS_TIMEOUT)
return STATUS_TIMEOUT;
}
return STATUS_WAIT_0;
}
}
/******************************************************************************
* RtlInitializeCriticalSection (NTDLL.@)
*/
NTSTATUS WINAPI RtlInitializeCriticalSection( RTL_CRITICAL_SECTION *crit )
{
return RtlInitializeCriticalSectionEx( crit, 0, 0 );
}
/******************************************************************************
* RtlInitializeCriticalSectionAndSpinCount (NTDLL.@)
*/
NTSTATUS WINAPI RtlInitializeCriticalSectionAndSpinCount( RTL_CRITICAL_SECTION *crit, ULONG spincount )
{
return RtlInitializeCriticalSectionEx( crit, spincount, 0 );
}
/******************************************************************************
* RtlInitializeCriticalSectionEx (NTDLL.@)
*/
NTSTATUS WINAPI RtlInitializeCriticalSectionEx( RTL_CRITICAL_SECTION *crit, ULONG spincount, ULONG flags )
{
if (flags & (RTL_CRITICAL_SECTION_FLAG_DYNAMIC_SPIN|RTL_CRITICAL_SECTION_FLAG_STATIC_INIT))
FIXME("(%p,%u,0x%08x) semi-stub\n", crit, spincount, flags);
/* FIXME: if RTL_CRITICAL_SECTION_FLAG_STATIC_INIT is given, we should use
* memory from a static pool to hold the debug info. Then heap.c could pass
* this flag rather than initialising the process heap CS by hand. If this
* is done, then debug info should be managed through Rtlp[Allocate|Free]DebugInfo
* so (e.g.) MakeCriticalSectionGlobal() doesn't free it using HeapFree().
*/
if (flags & RTL_CRITICAL_SECTION_FLAG_NO_DEBUG_INFO)
crit->DebugInfo = no_debug_info_marker;
else
{
crit->DebugInfo = RtlAllocateHeap( GetProcessHeap(), 0, sizeof(RTL_CRITICAL_SECTION_DEBUG ));
if (crit->DebugInfo)
{
crit->DebugInfo->Type = 0;
crit->DebugInfo->CreatorBackTraceIndex = 0;
crit->DebugInfo->CriticalSection = crit;
crit->DebugInfo->ProcessLocksList.Blink = &crit->DebugInfo->ProcessLocksList;
crit->DebugInfo->ProcessLocksList.Flink = &crit->DebugInfo->ProcessLocksList;
crit->DebugInfo->EntryCount = 0;
crit->DebugInfo->ContentionCount = 0;
memset( crit->DebugInfo->Spare, 0, sizeof(crit->DebugInfo->Spare) );
}
}
crit->LockCount = -1;
crit->RecursionCount = 0;
crit->OwningThread = 0;
crit->LockSemaphore = 0;
if (NtCurrentTeb()->Peb->NumberOfProcessors <= 1) spincount = 0;
crit->SpinCount = spincount & ~0x80000000;
return STATUS_SUCCESS;
}
/******************************************************************************
* RtlSetCriticalSectionSpinCount (NTDLL.@)
*/
ULONG WINAPI RtlSetCriticalSectionSpinCount( RTL_CRITICAL_SECTION *crit, ULONG spincount )
{
ULONG oldspincount = crit->SpinCount;
if (NtCurrentTeb()->Peb->NumberOfProcessors <= 1) spincount = 0;
crit->SpinCount = spincount;
return oldspincount;
}
/******************************************************************************
* RtlDeleteCriticalSection (NTDLL.@)
*/
NTSTATUS WINAPI RtlDeleteCriticalSection( RTL_CRITICAL_SECTION *crit )
{
crit->LockCount = -1;
crit->RecursionCount = 0;
crit->OwningThread = 0;
if (crit_section_has_debuginfo( crit ))
{
/* only free the ones we made in here */
if (!crit->DebugInfo->Spare[0])
{
RtlFreeHeap( GetProcessHeap(), 0, crit->DebugInfo );
crit->DebugInfo = NULL;
}
}
else NtClose( crit->LockSemaphore );
crit->LockSemaphore = 0;
return STATUS_SUCCESS;
}
/******************************************************************************
* RtlpWaitForCriticalSection (NTDLL.@)
*/
NTSTATUS WINAPI RtlpWaitForCriticalSection( RTL_CRITICAL_SECTION *crit )
{
LONGLONG timeout = NtCurrentTeb()->Peb->CriticalSectionTimeout.QuadPart / -10000000;
/* Don't allow blocking on a critical section during process termination */
if (RtlDllShutdownInProgress())
{
WARN( "process %s is shutting down, returning STATUS_SUCCESS\n",
debugstr_w(NtCurrentTeb()->Peb->ProcessParameters->ImagePathName.Buffer) );
return STATUS_SUCCESS;
}
for (;;)
{
EXCEPTION_RECORD rec;
NTSTATUS status = wait_semaphore( crit, 5 );
timeout -= 5;
if ( status == STATUS_TIMEOUT )
{
const char *name = NULL;
if (crit_section_has_debuginfo( crit )) name = (char *)crit->DebugInfo->Spare[0];
if (!name) name = "?";
ERR( "section %p %s wait timed out in thread %04x, blocked by %04x, retrying (60 sec)\n",
crit, debugstr_a(name), GetCurrentThreadId(), HandleToULong(crit->OwningThread) );
status = wait_semaphore( crit, 60 );
timeout -= 60;
if ( status == STATUS_TIMEOUT && TRACE_ON(relay) )
{
ERR( "section %p %s wait timed out in thread %04x, blocked by %04x, retrying (5 min)\n",
crit, debugstr_a(name), GetCurrentThreadId(), HandleToULong(crit->OwningThread) );
status = wait_semaphore( crit, 300 );
timeout -= 300;
}
}
if (status == STATUS_WAIT_0) break;
/* Throw exception only for Wine internal locks */
if (!crit_section_has_debuginfo( crit ) || !crit->DebugInfo->Spare[0]) continue;
/* only throw deadlock exception if configured timeout is reached */
if (timeout > 0) continue;
rec.ExceptionCode = STATUS_POSSIBLE_DEADLOCK;
rec.ExceptionFlags = 0;
rec.ExceptionRecord = NULL;
rec.ExceptionAddress = RtlRaiseException; /* sic */
rec.NumberParameters = 1;
rec.ExceptionInformation[0] = (ULONG_PTR)crit;
RtlRaiseException( &rec );
}
if (crit_section_has_debuginfo( crit )) crit->DebugInfo->ContentionCount++;
return STATUS_SUCCESS;
}
/******************************************************************************
* RtlpUnWaitCriticalSection (NTDLL.@)
*/
NTSTATUS WINAPI RtlpUnWaitCriticalSection( RTL_CRITICAL_SECTION *crit )
{
NTSTATUS ret;
/* debug info is cleared by MakeCriticalSectionGlobal */
if (!crit_section_has_debuginfo( crit ))
{
HANDLE sem = get_semaphore( crit );
ret = NtReleaseSemaphore( sem, 1, NULL );
}
else
{
int *lock = (int *)&crit->LockSemaphore;
InterlockedExchange( lock, 1 );
RtlWakeAddressSingle( lock );
ret = STATUS_SUCCESS;
}
if (ret) RtlRaiseStatus( ret );
return ret;
}
static inline void small_pause(void)
{
#ifdef __i386__
__asm__ __volatile__( "rep;nop" : : : "memory" );
#else
__asm__ __volatile__( "" : : : "memory" );
#endif
}
/******************************************************************************
* RtlEnterCriticalSection (NTDLL.@)
*/
NTSTATUS WINAPI RtlEnterCriticalSection( RTL_CRITICAL_SECTION *crit )
{
if (crit->SpinCount)
{
ULONG count;
if (RtlTryEnterCriticalSection( crit )) return STATUS_SUCCESS;
for (count = crit->SpinCount; count > 0; count--)
{
if (crit->LockCount > 0) break; /* more than one waiter, don't bother spinning */
if (crit->LockCount == -1) /* try again */
{
if (InterlockedCompareExchange( &crit->LockCount, 0, -1 ) == -1) goto done;
}
small_pause();
}
}
if (InterlockedIncrement( &crit->LockCount ))
{
if (crit->OwningThread == ULongToHandle(GetCurrentThreadId()))
{
crit->RecursionCount++;
return STATUS_SUCCESS;
}
/* Now wait for it */
RtlpWaitForCriticalSection( crit );
}
done:
crit->OwningThread = ULongToHandle(GetCurrentThreadId());
crit->RecursionCount = 1;
return STATUS_SUCCESS;
}
/******************************************************************************
* RtlTryEnterCriticalSection (NTDLL.@)
*/
BOOL WINAPI RtlTryEnterCriticalSection( RTL_CRITICAL_SECTION *crit )
{
BOOL ret = FALSE;
if (InterlockedCompareExchange( &crit->LockCount, 0, -1 ) == -1)
{
crit->OwningThread = ULongToHandle(GetCurrentThreadId());
crit->RecursionCount = 1;
ret = TRUE;
}
else if (crit->OwningThread == ULongToHandle(GetCurrentThreadId()))
{
InterlockedIncrement( &crit->LockCount );
crit->RecursionCount++;
ret = TRUE;
}
return ret;
}
/******************************************************************************
* RtlIsCriticalSectionLocked (NTDLL.@)
*/
BOOL WINAPI RtlIsCriticalSectionLocked( RTL_CRITICAL_SECTION *crit )
{
return crit->RecursionCount != 0;
}
/******************************************************************************
* RtlIsCriticalSectionLockedByThread (NTDLL.@)
*/
BOOL WINAPI RtlIsCriticalSectionLockedByThread( RTL_CRITICAL_SECTION *crit )
{
return crit->OwningThread == ULongToHandle(GetCurrentThreadId()) &&
crit->RecursionCount;
}
/******************************************************************************
* RtlLeaveCriticalSection (NTDLL.@)
*/
NTSTATUS WINAPI RtlLeaveCriticalSection( RTL_CRITICAL_SECTION *crit )
{
if (--crit->RecursionCount)
{
if (crit->RecursionCount > 0) InterlockedDecrement( &crit->LockCount );
else ERR( "section %p is not acquired\n", crit );
}
else
{
crit->OwningThread = 0;
if (InterlockedDecrement( &crit->LockCount ) >= 0)
{
/* someone is waiting */
RtlpUnWaitCriticalSection( crit );
}
}
return STATUS_SUCCESS;
}
/******************************************************************
* RtlRunOnceExecuteOnce (NTDLL.@)
*/
DWORD WINAPI RtlRunOnceExecuteOnce( RTL_RUN_ONCE *once, PRTL_RUN_ONCE_INIT_FN func,
void *param, void **context )
{
DWORD ret = RtlRunOnceBeginInitialize( once, 0, context );
if (ret != STATUS_PENDING) return ret;
if (!func( once, param, context ))
{
RtlRunOnceComplete( once, RTL_RUN_ONCE_INIT_FAILED, NULL );
return STATUS_UNSUCCESSFUL;
}
return RtlRunOnceComplete( once, 0, context ? *context : NULL );
}
struct srw_lock
{
short exclusive_waiters;
/* Number of shared owners, or -1 if owned exclusive.
*
* Sadly Windows has no equivalent to FUTEX_WAIT_BITSET, so in order to wake
* up *only* exclusive or *only* shared waiters (and thus avoid spurious
* wakeups), we need to wait on two different addresses.
* RtlAcquireSRWLockShared() needs to know the values of "exclusive_waiters"
* and "owners", but RtlAcquireSRWLockExclusive() only needs to know the
* value of "owners", so the former can wait on the entire structure, and
* the latter waits only on the "owners" member. Note then that "owners"
* must not be the first element in the structure.
*/
short owners;
};
C_ASSERT( sizeof(struct srw_lock) == 4 );
/***********************************************************************
* RtlInitializeSRWLock (NTDLL.@)
*
* NOTES
* Please note that SRWLocks do not keep track of the owner of a lock.
* It doesn't make any difference which thread for example unlocks an
* SRWLock (see corresponding tests). This implementation uses two
* keyed events (one for the exclusive waiters and one for the shared
* waiters) and is limited to 2^15-1 waiting threads.
*/
void WINAPI RtlInitializeSRWLock( RTL_SRWLOCK *lock )
{
lock->Ptr = NULL;
}
/***********************************************************************
* RtlAcquireSRWLockExclusive (NTDLL.@)
*
* NOTES
* Unlike RtlAcquireResourceExclusive this function doesn't allow
* nested calls from the same thread. "Upgrading" a shared access lock
* to an exclusive access lock also doesn't seem to be supported.
*/
void WINAPI RtlAcquireSRWLockExclusive( RTL_SRWLOCK *lock )
{
union { RTL_SRWLOCK *rtl; struct srw_lock *s; LONG *l; } u = { lock };
InterlockedIncrement16( &u.s->exclusive_waiters );
for (;;)
{
union { struct srw_lock s; LONG l; } old, new;
BOOL wait;
do
{
old.s = *u.s;
new.s = old.s;
if (!old.s.owners)
{
/* Not locked exclusive or shared. We can try to grab it. */
new.s.owners = -1;
--new.s.exclusive_waiters;
wait = FALSE;
}
else
{
wait = TRUE;
}
} while (InterlockedCompareExchange( u.l, new.l, old.l ) != old.l);
if (!wait) return;
RtlWaitOnAddress( &u.s->owners, &new.s.owners, sizeof(short), NULL );
}
}
/***********************************************************************
* RtlAcquireSRWLockShared (NTDLL.@)
*
* NOTES
* Do not call this function recursively - it will only succeed when
* there are no threads waiting for an exclusive lock!
*/
void WINAPI RtlAcquireSRWLockShared( RTL_SRWLOCK *lock )
{
union { RTL_SRWLOCK *rtl; struct srw_lock *s; LONG *l; } u = { lock };
for (;;)
{
union { struct srw_lock s; LONG l; } old, new;
BOOL wait;
do
{
old.s = *u.s;
new = old;
if (old.s.owners != -1 && !old.s.exclusive_waiters)
{
/* Not locked exclusive, and no exclusive waiters.
* We can try to grab it. */
++new.s.owners;
wait = FALSE;
}
else
{
wait = TRUE;
}
} while (InterlockedCompareExchange( u.l, new.l, old.l ) != old.l);
if (!wait) return;
RtlWaitOnAddress( u.s, &new.s, sizeof(struct srw_lock), NULL );
}
}
/***********************************************************************
* RtlReleaseSRWLockExclusive (NTDLL.@)
*/
void WINAPI RtlReleaseSRWLockExclusive( RTL_SRWLOCK *lock )
{
union { RTL_SRWLOCK *rtl; struct srw_lock *s; LONG *l; } u = { lock };
union { struct srw_lock s; LONG l; } old, new;
do
{
old.s = *u.s;
new = old;
if (old.s.owners != -1) ERR("Lock %p is not owned exclusive!\n", lock);
new.s.owners = 0;
} while (InterlockedCompareExchange( u.l, new.l, old.l ) != old.l);
if (new.s.exclusive_waiters)
RtlWakeAddressSingle( &u.s->owners );
else
RtlWakeAddressAll( u.s );
}
/***********************************************************************
* RtlReleaseSRWLockShared (NTDLL.@)
*/
void WINAPI RtlReleaseSRWLockShared( RTL_SRWLOCK *lock )
{
union { RTL_SRWLOCK *rtl; struct srw_lock *s; LONG *l; } u = { lock };
union { struct srw_lock s; LONG l; } old, new;
do
{
old.s = *u.s;
new = old;
if (old.s.owners == -1) ERR("Lock %p is owned exclusive!\n", lock);
else if (!old.s.owners) ERR("Lock %p is not owned shared!\n", lock);
--new.s.owners;
} while (InterlockedCompareExchange( u.l, new.l, old.l ) != old.l);
if (!new.s.owners)
RtlWakeAddressSingle( &u.s->owners );
}
/***********************************************************************
* RtlTryAcquireSRWLockExclusive (NTDLL.@)
*
* NOTES
* Similarly to AcquireSRWLockExclusive, recursive calls are not allowed
* and will fail with a FALSE return value.
*/
BOOLEAN WINAPI RtlTryAcquireSRWLockExclusive( RTL_SRWLOCK *lock )
{
union { RTL_SRWLOCK *rtl; struct srw_lock *s; LONG *l; } u = { lock };
union { struct srw_lock s; LONG l; } old, new;
BOOLEAN ret;
do
{
old.s = *u.s;
new.s = old.s;
if (!old.s.owners)
{
/* Not locked exclusive or shared. We can try to grab it. */
new.s.owners = -1;
ret = TRUE;
}
else
{
ret = FALSE;
}
} while (InterlockedCompareExchange( u.l, new.l, old.l ) != old.l);
return ret;
}
/***********************************************************************
* RtlTryAcquireSRWLockShared (NTDLL.@)
*/
BOOLEAN WINAPI RtlTryAcquireSRWLockShared( RTL_SRWLOCK *lock )
{
union { RTL_SRWLOCK *rtl; struct srw_lock *s; LONG *l; } u = { lock };
union { struct srw_lock s; LONG l; } old, new;
BOOLEAN ret;
do
{
old.s = *u.s;
new.s = old.s;
if (old.s.owners != -1 && !old.s.exclusive_waiters)
{
/* Not locked exclusive, and no exclusive waiters.
* We can try to grab it. */
++new.s.owners;
ret = TRUE;
}
else
{
ret = FALSE;
}
} while (InterlockedCompareExchange( u.l, new.l, old.l ) != old.l);
return ret;
}
/***********************************************************************
* RtlInitializeConditionVariable (NTDLL.@)
*
* Initializes the condition variable with NULL.
*
* PARAMS
* variable [O] condition variable
*
* RETURNS
* Nothing.
*/
void WINAPI RtlInitializeConditionVariable( RTL_CONDITION_VARIABLE *variable )
{
variable->Ptr = NULL;
}
/***********************************************************************
* RtlWakeConditionVariable (NTDLL.@)
*
* Wakes up one thread waiting on the condition variable.
*
* PARAMS
* variable [I/O] condition variable to wake up.
*
* RETURNS
* Nothing.
*
* NOTES
* The calling thread does not have to own any lock in order to call
* this function.
*/
void WINAPI RtlWakeConditionVariable( RTL_CONDITION_VARIABLE *variable )
{
InterlockedIncrement( (int *)&variable->Ptr );
RtlWakeAddressSingle( variable );
}
/***********************************************************************
* RtlWakeAllConditionVariable (NTDLL.@)
*
* See WakeConditionVariable, wakes up all waiting threads.
*/
void WINAPI RtlWakeAllConditionVariable( RTL_CONDITION_VARIABLE *variable )
{
InterlockedIncrement( (int *)&variable->Ptr );
RtlWakeAddressAll( variable );
}
/***********************************************************************
* RtlSleepConditionVariableCS (NTDLL.@)
*
* Atomically releases the critical section and suspends the thread,
* waiting for a Wake(All)ConditionVariable event. Afterwards it enters
* the critical section again and returns.
*
* PARAMS
* variable [I/O] condition variable
* crit [I/O] critical section to leave temporarily
* timeout [I] timeout
*
* RETURNS
* see NtWaitForKeyedEvent for all possible return values.
*/
NTSTATUS WINAPI RtlSleepConditionVariableCS( RTL_CONDITION_VARIABLE *variable, RTL_CRITICAL_SECTION *crit,
const LARGE_INTEGER *timeout )
{
int value = *(int *)&variable->Ptr;
NTSTATUS status;
RtlLeaveCriticalSection( crit );
status = RtlWaitOnAddress( &variable->Ptr, &value, sizeof(value), timeout );
RtlEnterCriticalSection( crit );
return status;
}
/***********************************************************************
* RtlSleepConditionVariableSRW (NTDLL.@)
*
* Atomically releases the SRWLock and suspends the thread,
* waiting for a Wake(All)ConditionVariable event. Afterwards it enters
* the SRWLock again with the same access rights and returns.
*
* PARAMS
* variable [I/O] condition variable
* lock [I/O] SRWLock to leave temporarily
* timeout [I] timeout
* flags [I] type of the current lock (exclusive / shared)
*
* RETURNS
* see NtWaitForKeyedEvent for all possible return values.
*
* NOTES
* the behaviour is undefined if the thread doesn't own the lock.
*/
NTSTATUS WINAPI RtlSleepConditionVariableSRW( RTL_CONDITION_VARIABLE *variable, RTL_SRWLOCK *lock,
const LARGE_INTEGER *timeout, ULONG flags )
{
int value = *(int *)&variable->Ptr;
NTSTATUS status;
if (flags & RTL_CONDITION_VARIABLE_LOCKMODE_SHARED)
RtlReleaseSRWLockShared( lock );
else
RtlReleaseSRWLockExclusive( lock );
status = RtlWaitOnAddress( &variable->Ptr, &value, sizeof(value), timeout );
if (flags & RTL_CONDITION_VARIABLE_LOCKMODE_SHARED)
RtlAcquireSRWLockShared( lock );
else
RtlAcquireSRWLockExclusive( lock );
return status;
}
/* RtlWaitOnAddress() and RtlWakeAddress*(), hereafter referred to as "Win32
* futexes", offer futex-like semantics with a variable set of address sizes,
* but are limited to a single process. They are also fair—the documentation
* specifies this, and tests bear it out.
*
* On Windows they are implemented using NtAlertThreadByThreadId and
* NtWaitForAlertByThreadId, which manipulate a single flag (similar to an
* auto-reset event) per thread. This can be tested by attempting to wake a
* thread waiting in RtlWaitOnAddress() via NtAlertThreadByThreadId.
*/
struct futex_entry
{
struct list entry;
const void *addr;
DWORD tid;
};
struct futex_queue
{
struct list queue;
LONG lock;
};
static struct futex_queue futex_queues[256];
static struct futex_queue *get_futex_queue( const void *addr )
{
ULONG_PTR val = (ULONG_PTR)addr;
return &futex_queues[(val >> 4) % ARRAY_SIZE(futex_queues)];
}
static void spin_lock( LONG *lock )
{
while (InterlockedCompareExchange( lock, -1, 0 ))
YieldProcessor();
}
static void spin_unlock( LONG *lock )
{
InterlockedExchange( lock, 0 );
}
static BOOL compare_addr( const void *addr, const void *cmp, SIZE_T size )
{
switch (size)
{
case 1:
return (*(const UCHAR *)addr == *(const UCHAR *)cmp);
case 2:
return (*(const USHORT *)addr == *(const USHORT *)cmp);
case 4:
return (*(const ULONG *)addr == *(const ULONG *)cmp);
case 8:
return (*(const ULONG64 *)addr == *(const ULONG64 *)cmp);
}
return FALSE;
}
/***********************************************************************
* RtlWaitOnAddress (NTDLL.@)
*/
NTSTATUS WINAPI RtlWaitOnAddress( const void *addr, const void *cmp, SIZE_T size,
const LARGE_INTEGER *timeout )
{
struct futex_queue *queue = get_futex_queue( addr );
struct futex_entry entry;
NTSTATUS ret;
TRACE("addr %p cmp %p size %#Ix timeout %s\n", addr, cmp, size, debugstr_timeout( timeout ));
if (size != 1 && size != 2 && size != 4 && size != 8)
return STATUS_INVALID_PARAMETER;
entry.addr = addr;
entry.tid = GetCurrentThreadId();
spin_lock( &queue->lock );
/* Do the comparison inside of the spinlock, to reduce spurious wakeups. */
if (!compare_addr( addr, cmp, size ))
{
spin_unlock( &queue->lock );
return STATUS_SUCCESS;
}
if (!queue->queue.next)
list_init( &queue->queue );
list_add_tail( &queue->queue, &entry.entry );
spin_unlock( &queue->lock );
ret = NtWaitForAlertByThreadId( NULL, timeout );
spin_lock( &queue->lock );
/* We may have already been removed by a call to RtlWakeAddressSingle(). */
if (entry.addr)
list_remove( &entry.entry );
spin_unlock( &queue->lock );
TRACE("returning %#x\n", ret);
if (ret == STATUS_ALERTED) ret = STATUS_SUCCESS;
return ret;
}
/***********************************************************************
* RtlWakeAddressAll (NTDLL.@)
*/
void WINAPI RtlWakeAddressAll( const void *addr )
{
struct futex_queue *queue = get_futex_queue( addr );
unsigned int count = 0, i;
struct futex_entry *entry;
DWORD tids[256];
TRACE("%p\n", addr);
if (!addr) return;
spin_lock( &queue->lock );
if (!queue->queue.next)
list_init(&queue->queue);
LIST_FOR_EACH_ENTRY( entry, &queue->queue, struct futex_entry, entry )
{
if (entry->addr == addr)
{
/* Try to buffer wakes, so that we don't make a system call while
* holding a spinlock. */
if (count < ARRAY_SIZE(tids))
tids[count++] = entry->tid;
else
NtAlertThreadByThreadId( (HANDLE)(DWORD_PTR)entry->tid );
}
}
spin_unlock( &queue->lock );
for (i = 0; i < count; ++i)
NtAlertThreadByThreadId( (HANDLE)(DWORD_PTR)tids[i] );
}
/***********************************************************************
* RtlWakeAddressSingle (NTDLL.@)
*/
void WINAPI RtlWakeAddressSingle( const void *addr )
{
struct futex_queue *queue = get_futex_queue( addr );
struct futex_entry *entry;
DWORD tid = 0;
TRACE("%p\n", addr);
if (!addr) return;
spin_lock( &queue->lock );
if (!queue->queue.next)
list_init(&queue->queue);
LIST_FOR_EACH_ENTRY( entry, &queue->queue, struct futex_entry, entry )
{
if (entry->addr == addr)
{
/* Try to buffer wakes, so that we don't make a system call while
* holding a spinlock. */
tid = entry->tid;
/* Remove this entry from the queue, so that a simultaneous call to
* RtlWakeAddressSingle() will not also wake it—two simultaneous
* calls must wake at least two waiters if they exist. */
entry->addr = NULL;
list_remove( &entry->entry );
break;
}
}
spin_unlock( &queue->lock );
if (tid) NtAlertThreadByThreadId( (HANDLE)(DWORD_PTR)tid );
}
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