Hmm,
THis should have been patch 0021 instead of 0012 , please disregard.
Ciao, Marcus On Wed, Jan 01, 2014 at 07:44:16PM +0100, Marcus Meissner wrote:
Hi,
Additional tightening and cleaning of comments.
After Alexandres last guidance ("no global allocation") and some hours of hair pulling I now did a implementation with just a linked list of waiters.
variable->Ptr points to the head of this list.
The bit 0 of variable->Ptr is used for atomic locking of the list and also its content, avoiding need for a lock variable.
Small issues: We are busy waiting on the bit 0 lock, not the most performance wise best thing.
Ciao, Marcus
dlls/kernel32/kernel32.spec | 4 ++ dlls/kernel32/sync.c | 151 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 155 insertions(+)
diff --git a/dlls/kernel32/kernel32.spec b/dlls/kernel32/kernel32.spec index 7779a75..e8d2bf0 100644 --- a/dlls/kernel32/kernel32.spec +++ b/dlls/kernel32/kernel32.spec @@ -750,6 +750,7 @@ @ stdcall InitOnceComplete(ptr long ptr) @ stdcall InitOnceExecuteOnce(ptr ptr ptr ptr) @ stdcall InitOnceInitialize(ptr) ntdll.RtlRunOnceInitialize +@ stdcall InitializeConditionVariable(ptr) @ stdcall InitializeCriticalSection(ptr) @ stdcall InitializeCriticalSectionAndSpinCount(ptr long) @ stdcall InitializeCriticalSectionEx(ptr long long) @@ -1194,6 +1195,7 @@ @ stdcall SignalObjectAndWait(long long long long) @ stdcall SizeofResource(long long) @ stdcall Sleep(long) +@ stdcall SleepConditionVariableCS(ptr ptr long) @ stdcall SleepEx(long long) @ stdcall SuspendThread(long) @ stdcall SwitchToFiber(ptr) @@ -1263,6 +1265,8 @@ @ stdcall WaitForSingleObjectEx(long long long) @ stdcall WaitNamedPipeA (str long) @ stdcall WaitNamedPipeW (wstr long) +@ stdcall WakeAllConditionVariable (ptr) +@ stdcall WakeConditionVariable (ptr) @ stdcall WerRegisterFile(wstr long long) @ stdcall WerRegisterMemoryBlock(ptr long) @ stdcall WerRegisterRuntimeExceptionModule(wstr ptr) diff --git a/dlls/kernel32/sync.c b/dlls/kernel32/sync.c index 3c9e42a..34f39cd 100644 --- a/dlls/kernel32/sync.c +++ b/dlls/kernel32/sync.c @@ -2327,3 +2327,154 @@ __ASM_STDCALL_FUNC(InterlockedDecrement, 4, "ret $4")
#endif /* __i386__ */
+/* See http://locklessinc.com/articles/mutex_cv_futex/ for a futex implementation
- See http://www.cs.wustl.edu/~schmidt/win32-cv-1.html for various implementations
- of pthread_cond_* with Win32 primitives.
- See glibc/nptl/DESIGN-condvar.txt for the glibc implementation
- This implementation uses a linked list as waiter queue, and the list
- and its content is locked for access via bit 0 of variable->Ptr.
- The actual waiting is done using a Win32 Event.
- */
+struct _condvar_intern {
- struct _condvar_intern *next;
- HANDLE event;
+};
+/**********************************************************************
InitializeConditionVariable (KERNEL32.@)- */
+VOID WINAPI InitializeConditionVariable(PCONDITION_VARIABLE variable) +{
- variable->Ptr = NULL;
+}
+/*
- We lock the condition variable by setting bit 0 in variable->Ptr
- atomically. We busy loop until we succeed and return the current value.
- We also lock the empty list (NULL).
- List unlocking is done with "variable->Ptr = <retvalue>"
- */
+static struct _condvar_intern* +_lock_list (PCONDITION_VARIABLE variable) {
- struct _condvar_intern *oldvar, *var;
- do {
__asm__ __volatile__("":::"memory");var = variable->Ptr;if ((DWORD_PTR)var & 1) continue; /* locked already, retry. */oldvar = InterlockedCompareExchangePointer (&variable->Ptr, (void*)((DWORD_PTR)var|1), var);if (oldvar == var)break;/* failed atomic locking, retry. */- } while (1);
- return var;
+}
+/**********************************************************************
WakeConditionVariable (KERNEL32.@)- */
+VOID WINAPI WakeConditionVariable(PCONDITION_VARIABLE variable) +{
- struct _condvar_intern *var;
- if (!variable->Ptr)
return;- var = _lock_list (variable);
- if (!var) {
variable->Ptr = NULL;return;- }
- /* remove and wake up the first entry */
- NtSetEvent (var->event, NULL);
- variable->Ptr = var->next;
+}
+/**********************************************************************
WakeAllConditionVariable (KERNEL32.@)- */
+VOID WINAPI WakeAllConditionVariable(PCONDITION_VARIABLE variable) +{
- struct _condvar_intern *var;
- if (!variable->Ptr)
return;- var = _lock_list (variable);
- /* dequeue the whole waiter chain and wake it up */
- while (var) {
NtSetEvent (var->event, NULL);var = var->next;- }
- variable->Ptr = NULL;
+}
+/**********************************************************************
SleepConditionVariableCS (KERNEL32.@)- */
+BOOL WINAPI SleepConditionVariableCS(PCONDITION_VARIABLE variable,
- LPCRITICAL_SECTION crit, DWORD timeout
+) +{
- struct _condvar_intern myself;
- struct _condvar_intern **xvar, *var;
- BOOL ret = TRUE;
- OBJECT_ATTRIBUTES attr;
- DWORD res;
- attr.Length = sizeof(attr);
- attr.RootDirectory = 0;
- attr.Attributes = OBJ_INHERIT;
- attr.ObjectName = NULL;
- attr.SecurityDescriptor = NULL;
- attr.SecurityQualityOfService = NULL;
- NtCreateEvent (&myself.event, EVENT_ALL_ACCESS, &attr, NotificationEvent, 0);
- myself.next = NULL;
- var = _lock_list (variable);
- /* Attach our stack based struct to the end of the list.
* (at the end for fairness)*/- xvar = &var;
- while (*xvar)
xvar = &(*xvar)->next;- *xvar = &myself;
- variable->Ptr = var;
- RtlLeaveCriticalSection(crit);
- res = WaitForSingleObject(myself.event, timeout);
- var = _lock_list (variable);
- /* Remove our entry */
- xvar = (struct _condvar_intern **)&var;
- while (*xvar) {
if (*xvar == &myself) {*xvar = (*xvar)->next;break;}xvar = &(*xvar)->next;- }
- variable->Ptr = var;
- CloseHandle (myself.event);
- RtlEnterCriticalSection(crit);
- if (res == WAIT_TIMEOUT) {
ret = FALSE;/* expected from caller, but not set by WaitForSingleObject */SetLastError(ERROR_TIMEOUT);- }
- return ret;
+}
1.7.10.4