[NTDLL_VISTA]
[reactos.git] / reactos / dll / win32 / ntdll_vista / condvar.c
1 /*
2 * COPYRIGHT: See COPYING in the top level directory
3 * PROJECT: ReactOS system libraries
4 * PURPOSE: Condition Variable Routines
5 * PROGRAMMERS: Thomas Weidenmueller <w3seek@reactos.com>
6 * Stephan A. R�ger
7 */
8
9 /* NOTE: This functionality can be optimized for releasing single
10 threads or for releasing all waiting threads at once. This
11 implementation is optimized for releasing a single thread at a time.
12 It wakes up sleeping threads in FIFO order. */
13
14 /* INCLUDES ******************************************************************/
15
16 #include <rtl_vista.h>
17
18 #define NDEBUG
19 #include <debug.h>
20
21 /* INTERNAL TYPES ************************************************************/
22
23 #define COND_VAR_UNUSED_FLAG ((ULONG_PTR)1)
24 #define COND_VAR_LOCKED_FLAG ((ULONG_PTR)2)
25 #define COND_VAR_FLAGS_MASK ((ULONG_PTR)3)
26 #define COND_VAR_ADDRESS_MASK (~COND_VAR_FLAGS_MASK)
27
28 typedef struct _COND_VAR_WAIT_ENTRY
29 {
30 /* ListEntry must have an alignment of at least 32-bits, since we
31 want COND_VAR_ADDRESS_MASK to cover all of the address. */
32 LIST_ENTRY ListEntry;
33 PVOID WaitKey;
34 BOOLEAN ListRemovalHandled;
35 } COND_VAR_WAIT_ENTRY, * PCOND_VAR_WAIT_ENTRY;
36
37 #define CONTAINING_COND_VAR_WAIT_ENTRY(address, field) \
38 CONTAINING_RECORD(address, COND_VAR_WAIT_ENTRY, field)
39
40 /* GLOBALS *******************************************************************/
41
42 static HANDLE CondVarKeyedEventHandle = NULL;
43
44 /* INTERNAL FUNCTIONS ********************************************************/
45
46 FORCEINLINE
47 ULONG_PTR
48 InternalCmpXChgCondVarAcq(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable,
49 IN ULONG_PTR Exchange,
50 IN ULONG_PTR Comperand)
51 {
52 return (ULONG_PTR)InterlockedCompareExchangePointerAcquire(&ConditionVariable->Ptr,
53 (PVOID)Exchange,
54 (PVOID)Comperand);
55 }
56
57 FORCEINLINE
58 ULONG_PTR
59 InternalCmpXChgCondVarRel(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable,
60 IN ULONG_PTR Exchange,
61 IN ULONG_PTR Comperand)
62 {
63 return (ULONG_PTR)InterlockedCompareExchangePointerRelease(&ConditionVariable->Ptr,
64 (PVOID)Exchange,
65 (PVOID)Comperand);
66 }
67
68 FORCEINLINE
69 BOOLEAN *
70 InternalGetListRemovalHandledFlag(IN PCOND_VAR_WAIT_ENTRY Entry)
71 {
72 return (BOOLEAN *)&Entry->ListRemovalHandled;
73 }
74
75 static
76 PCOND_VAR_WAIT_ENTRY
77 InternalLockCondVar(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable,
78 IN PCOND_VAR_WAIT_ENTRY InsertEntry OPTIONAL,
79 IN BOOLEAN * AbortIfLocked OPTIONAL)
80 {
81 /* InsertEntry and AbortIfLocked may be NULL on entry. This routine
82 will return NULL if the lock was not acquired. Otherwise it has
83 successfully acquired the lock and the return value is a valid
84 reference to the list head associated with ConditionVariable.
85 The caller must in this case call InternalUnlockCondVar later
86 in order to unlock the condition variable.
87
88 If InsertEntry is NULL and there are no entries on the list, this
89 routine will not acquire the lock and return NULL. If InsertEntry
90 is not NULL this routine ensures that InsertEntry will be on the
91 list when it returns successfully.
92
93 If the lock is owned by another thread and AbortIfLocked is NULL,
94 this routine will block until it acquires the lock. If AbortIfLocked
95 is not NULL and the lock is owned by another thread, this routine
96 will periodically check if *AbortIfLocked is nonzero and if so, will
97 return NULL instead of continuing the wait. */
98
99 ULONG_PTR OldVal = (ULONG_PTR)ConditionVariable->Ptr;
100
101 for (;;)
102 {
103 ULONG_PTR NewVal, LockRes;
104 PLIST_ENTRY OldListHead;
105
106 if (OldVal & COND_VAR_LOCKED_FLAG)
107 {
108 /* The locked flag is set, indicating someone else currently
109 holds the lock. We'll spin until this flag becomes
110 clear or we're asked to abort. */
111 YieldProcessor();
112
113 if ((AbortIfLocked != NULL) && *AbortIfLocked)
114 {
115 /* The caller wants us to abort in this case. */
116 return NULL;
117 }
118
119 /* Refresh OldVal and try again. */
120 OldVal = *(ULONG_PTR *)&ConditionVariable->Ptr;
121 continue;
122 }
123
124 /* Retrieve the list head currently associated with the
125 condition variable. */
126 OldListHead = (PLIST_ENTRY)(OldVal & COND_VAR_ADDRESS_MASK);
127 if (InsertEntry == NULL)
128 {
129 /* The caller doesn't want to put any entry on the list. */
130 if (OldListHead == NULL)
131 {
132 /* The list is empty, so there is nothing to lock. */
133 return NULL;
134 }
135
136 /* The list isn't empty. In this case we need to preserve
137 all of OldVal. */
138 NewVal = OldVal;
139 }
140 else
141 {
142 /* Let InsertEntry be the new list head. Preserve only the
143 bits inside the COND_VAR_FLAGS_MASK range. */
144 NewVal = ((OldVal & COND_VAR_FLAGS_MASK) |
145 (ULONG_PTR)&InsertEntry->ListEntry);
146 }
147
148 /* Set the flag that indicates someone is holding the lock and
149 try to update the condition variable thread-safe. */
150 NewVal |= COND_VAR_LOCKED_FLAG;
151 LockRes = InternalCmpXChgCondVarAcq(ConditionVariable, NewVal, OldVal);
152 if (LockRes == OldVal)
153 {
154 /* We successfully updated ConditionVariable the way we
155 wanted and now hold the lock. */
156 if (InsertEntry == NULL)
157 {
158 /* We know that OldVal contains a valid address in
159 this case. */
160 ASSERT(OldListHead != NULL);
161 return CONTAINING_COND_VAR_WAIT_ENTRY(OldListHead, ListEntry);
162 }
163
164 /* InsertEntry is not on the list yet, so add it. In any
165 case InsertEntry will be the new list head. */
166 if (OldListHead == NULL)
167 {
168 /* List was empty before. */
169 InitializeListHead(&InsertEntry->ListEntry);
170 }
171 else
172 {
173 /* Make InsertEntry the last entry of the old list.
174 As InsertEntry will take the role as new list head,
175 OldListHead will become the second entry (InsertEntry->Flink)
176 on the new list. */
177 InsertTailList(OldListHead, &InsertEntry->ListEntry);
178 }
179
180 return InsertEntry;
181 }
182
183 /* We didn't manage to update ConditionVariable, so try again. */
184 OldVal = LockRes;
185 }
186 }
187
188 static
189 VOID
190 InternalUnlockCondVar(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable,
191 IN PCOND_VAR_WAIT_ENTRY RemoveEntry OPTIONAL)
192 {
193 /* This routine assumes that the lock is being held on entry.
194 RemoveEntry may be NULL. If it is not NULL, this routine
195 assumes that RemoveEntry is on the list and will remove it
196 before releasing the lock. */
197 ULONG_PTR OldVal = (ULONG_PTR)ConditionVariable->Ptr;
198 PLIST_ENTRY NewHeadEntry;
199
200 ASSERT((OldVal & COND_VAR_LOCKED_FLAG) &&
201 (OldVal & COND_VAR_ADDRESS_MASK));
202
203 NewHeadEntry = (PLIST_ENTRY)(OldVal & COND_VAR_ADDRESS_MASK);
204 if (RemoveEntry != NULL)
205 {
206 /* We have to drop RemoveEntry from the list. */
207 if (&RemoveEntry->ListEntry == NewHeadEntry)
208 {
209 /* RemoveEntry is the list head. */
210 if (!IsListEmpty(NewHeadEntry))
211 {
212 /* The second entry in the list will become the new
213 list head. It's from the thread that arrived
214 right before the owner of RemoveEntry. */
215 NewHeadEntry = NewHeadEntry->Flink;
216 RemoveEntryList(&RemoveEntry->ListEntry);
217 }
218 else
219 {
220 /* The list will be empty, so discard the list. */
221 NewHeadEntry = NULL;
222 }
223 }
224 else
225 {
226 /* RemoveEntry is not the list head. The current list head
227 will remain. */
228 RemoveEntryList(&RemoveEntry->ListEntry);
229 }
230
231 /* Indicate to the owner of RemoveEntry that the entry
232 was removed from the list. RemoveEntry may not be touched
233 from here on. We don't use volatile semantics here since
234 the cache will anyway be flushed soon when we update
235 ConditionVariable. */
236 RemoveEntry->ListRemovalHandled = TRUE;
237 }
238
239 /* Now unlock thread-safe, while preserving any flags within the
240 COND_VAR_FLAGS_MASK range except for COND_VAR_LOCKED_FLAG. */
241 for (;;)
242 {
243 ULONG_PTR NewVal = ((OldVal & (COND_VAR_FLAGS_MASK ^ COND_VAR_LOCKED_FLAG)) |
244 (ULONG_PTR)NewHeadEntry);
245 ULONG_PTR LockRes = InternalCmpXChgCondVarRel(ConditionVariable, NewVal, OldVal);
246 if (LockRes == OldVal)
247 {
248 /* We unlocked. */
249 break;
250 }
251
252 /* Try again. */
253 OldVal = LockRes;
254 }
255 }
256
257 static
258 VOID
259 InternalWake(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable,
260 IN BOOLEAN ReleaseAll)
261 {
262 /* If ReleaseAll is zero on entry, one thread at most will be woken.
263 Otherwise all waiting threads are woken. Wakeups happen in FIFO
264 order. */
265 PCOND_VAR_WAIT_ENTRY CONST HeadEntry = InternalLockCondVar(ConditionVariable, NULL, NULL);
266 PCOND_VAR_WAIT_ENTRY Entry;
267 PCOND_VAR_WAIT_ENTRY NextEntry;
268 LARGE_INTEGER Timeout;
269 PCOND_VAR_WAIT_ENTRY RemoveOnUnlockEntry;
270
271 ASSERT(CondVarKeyedEventHandle != NULL);
272
273 if (HeadEntry == NULL)
274 {
275 /* There is noone there to wake up. In this case do nothing
276 and return immediately. We don't stockpile releases. */
277 return;
278 }
279
280 Timeout.QuadPart = 0;
281 RemoveOnUnlockEntry = NULL;
282
283 /* Release sleeping threads. We will iterate from the last entry on
284 the list to the first. Note that the loop condition is always
285 true for the initial test. */
286 for (Entry = CONTAINING_COND_VAR_WAIT_ENTRY(HeadEntry->ListEntry.Blink, ListEntry);
287 Entry != NULL;
288 Entry = NextEntry)
289 {
290 NTSTATUS Status;
291
292 if (HeadEntry == Entry)
293 {
294 /* After the current entry we've iterated through the
295 entire list in backward direction. Then exit.*/
296 NextEntry = NULL;
297 }
298 else
299 {
300 /* Store away the next reference right now, since we may
301 not touch Entry anymore at the end of the block. */
302 NextEntry = CONTAINING_COND_VAR_WAIT_ENTRY(Entry->ListEntry.Blink, ListEntry);
303 }
304
305 /* Wake the thread associated with this event. We will
306 immediately return if we failed (zero timeout). */
307 Status = NtReleaseKeyedEvent(CondVarKeyedEventHandle,
308 &Entry->WaitKey,
309 FALSE,
310 &Timeout);
311
312 if (!NT_SUCCESS(Status))
313 {
314 /* We failed to wake a thread. We'll keep trying. */
315 ASSERT(STATUS_INVALID_HANDLE != Status);
316 continue;
317 }
318
319 /* We've woken a thread and will make sure this thread
320 is removed from the list. */
321 if (HeadEntry == Entry)
322 {
323 /* This is the list head. We can't remove it as easily as
324 other entries and will pass it to the unlock routine
325 later (we will exit the loop after this round anyway). */
326 RemoveOnUnlockEntry = HeadEntry;
327 }
328 else
329 {
330 /* We can remove the entry right away. */
331 RemoveEntryList(&Entry->ListEntry);
332
333 /* Now tell the woken thread that removal from the list was
334 already taken care of here so that this thread can resume
335 its normal operation more quickly. We may not touch
336 Entry after signaling this, since it may lie in invalid
337 memory from there on. */
338 *InternalGetListRemovalHandledFlag(Entry) = TRUE;
339 }
340
341 if (!ReleaseAll)
342 {
343 /* We've successfully woken one thread as the caller
344 demanded. */
345 break;
346 }
347 }
348
349 InternalUnlockCondVar(ConditionVariable, RemoveOnUnlockEntry);
350 }
351
352 VOID
353 NTAPI
354 RtlAcquireSRWLockExclusive(IN OUT PRTL_SRWLOCK SRWLock);
355 VOID
356 NTAPI
357 RtlAcquireSRWLockShared(IN OUT PRTL_SRWLOCK SRWLock);
358 VOID
359 NTAPI
360 RtlReleaseSRWLockExclusive(IN OUT PRTL_SRWLOCK SRWLock);
361 VOID
362 NTAPI
363 RtlReleaseSRWLockShared(IN OUT PRTL_SRWLOCK SRWLock);
364
365 static
366 NTSTATUS
367 InternalSleep(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable,
368 IN OUT PRTL_CRITICAL_SECTION CriticalSection OPTIONAL,
369 IN OUT PRTL_SRWLOCK SRWLock OPTIONAL,
370 IN ULONG SRWFlags,
371 IN const LARGE_INTEGER * TimeOut OPTIONAL)
372 {
373 /* Either CriticalSection or SRWLock must be NULL, but not both.
374 These caller provided lock must be held on entry and will be
375 held again on return. */
376
377 COND_VAR_WAIT_ENTRY OwnEntry;
378 NTSTATUS Status;
379
380 ASSERT(CondVarKeyedEventHandle != NULL);
381 ASSERT((CriticalSection == NULL) != (SRWLock == NULL));
382
383 RtlZeroMemory(&OwnEntry, sizeof(OwnEntry));
384
385 /* Put OwnEntry on the list. */
386 InternalLockCondVar(ConditionVariable, &OwnEntry, NULL);
387 InternalUnlockCondVar(ConditionVariable, NULL);
388
389 /* We can now drop the caller provided lock as a preparation for
390 going to sleep. */
391 if (CriticalSection == NULL)
392 {
393 if (0 == (RTL_CONDITION_VARIABLE_LOCKMODE_SHARED & SRWFlags))
394 {
395 RtlReleaseSRWLockExclusive(SRWLock);
396 }
397 else
398 {
399 RtlReleaseSRWLockShared(SRWLock);
400 }
401 }
402 else
403 {
404 RtlLeaveCriticalSection(CriticalSection);
405 }
406
407 /* Now sleep using the caller provided timeout. */
408 Status = NtWaitForKeyedEvent(CondVarKeyedEventHandle,
409 &OwnEntry.WaitKey,
410 FALSE,
411 (PLARGE_INTEGER)TimeOut);
412
413 ASSERT(STATUS_INVALID_HANDLE != Status);
414
415 if (!*InternalGetListRemovalHandledFlag(&OwnEntry))
416 {
417 /* Remove OwnEntry from the list again, since it still seems to
418 be on the list. We will know for sure once we've acquired
419 the lock. */
420 if (InternalLockCondVar(ConditionVariable,
421 NULL,
422 InternalGetListRemovalHandledFlag(&OwnEntry)))
423 {
424 /* Unlock and potentially remove OwnEntry. Self-removal is
425 usually only necessary when a timeout occurred. */
426 InternalUnlockCondVar(ConditionVariable,
427 !OwnEntry.ListRemovalHandled ?
428 &OwnEntry : NULL);
429 }
430 }
431
432 #if _DEBUG
433 /* Clear OwnEntry to aid in detecting bugs. */
434 RtlZeroMemory(&OwnEntry, sizeof(OwnEntry));
435 #endif
436
437 /* Reacquire the caller provided lock, as we are about to return. */
438 if (CriticalSection == NULL)
439 {
440 if (0 == (RTL_CONDITION_VARIABLE_LOCKMODE_SHARED & SRWFlags))
441 {
442 RtlAcquireSRWLockExclusive(SRWLock);
443 }
444 else
445 {
446 RtlAcquireSRWLockShared(SRWLock);
447 }
448 }
449 else
450 {
451 RtlEnterCriticalSection(CriticalSection);
452 }
453
454 /* Return whatever NtWaitForKeyedEvent returned. */
455 return Status;
456 }
457
458 VOID
459 RtlpInitializeKeyedEvent(VOID)
460 {
461 ASSERT(CondVarKeyedEventHandle == NULL);
462 NtCreateKeyedEvent(&CondVarKeyedEventHandle, EVENT_ALL_ACCESS, NULL, 0);
463 }
464
465 VOID
466 RtlpCloseKeyedEvent(VOID)
467 {
468 ASSERT(CondVarKeyedEventHandle != NULL);
469 NtClose(CondVarKeyedEventHandle);
470 CondVarKeyedEventHandle = NULL;
471 }
472
473 /* EXPORTED FUNCTIONS ********************************************************/
474
475 VOID
476 NTAPI
477 RtlInitializeConditionVariable(OUT PRTL_CONDITION_VARIABLE ConditionVariable)
478 {
479 ConditionVariable->Ptr = NULL;
480 }
481
482 VOID
483 NTAPI
484 RtlWakeConditionVariable(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable)
485 {
486 InternalWake(ConditionVariable, FALSE);
487 }
488
489 VOID
490 NTAPI
491 RtlWakeAllConditionVariable(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable)
492 {
493 InternalWake(ConditionVariable, TRUE);
494 }
495
496 NTSYSAPI
497 NTSTATUS
498 NTAPI
499 RtlSleepConditionVariableCS(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable,
500 IN OUT PRTL_CRITICAL_SECTION CriticalSection,
501 IN const LARGE_INTEGER * TimeOut OPTIONAL)
502 {
503 return InternalSleep(ConditionVariable,
504 CriticalSection,
505 (PRTL_SRWLOCK)NULL,
506 0,
507 TimeOut);
508 }
509
510 NTSYSAPI
511 NTSTATUS
512 NTAPI
513 RtlSleepConditionVariableSRW(IN OUT PRTL_CONDITION_VARIABLE ConditionVariable,
514 IN OUT PRTL_SRWLOCK SRWLock,
515 IN const LARGE_INTEGER * TimeOut OPTIONAL,
516 IN ULONG Flags)
517 {
518 return InternalSleep(ConditionVariable,
519 (PRTL_CRITICAL_SECTION)NULL,
520 SRWLock,
521 Flags,
522 TimeOut);
523 }
524
525 /* EOF */