semrw-generic.cpp@ 27124

Last change on this file since 27124 was 25908, checked in by vboxsync, 15 years ago
RTSemRWIsReadOwner: For assertion in main.
Property svn:eol-style set to `native` Property svn:keywords set to `Id`
File size: 29.5 KB

Line
1	/* $Id: semrw-generic.cpp 25908 2010-01-18 22:07:28Z vboxsync $ */
2	/** @file
3	* IPRT - Read-Write Semaphore, Generic.
4	*
5	* This is a generic implementation for OSes which don't have
6	* native RW semaphores.
7	*/
8
9	/*
10	* Copyright (C) 2006-2009 Sun Microsystems, Inc.
11	*
12	* This file is part of VirtualBox Open Source Edition (OSE), as
13	* available from http://www.virtualbox.org. This file is free software;
14	* you can redistribute it and/or modify it under the terms of the GNU
15	* General Public License (GPL) as published by the Free Software
16	* Foundation, in version 2 as it comes in the "COPYING" file of the
17	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
18	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
19	*
20	* The contents of this file may alternatively be used under the terms
21	* of the Common Development and Distribution License Version 1.0
22	* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
23	* VirtualBox OSE distribution, in which case the provisions of the
24	* CDDL are applicable instead of those of the GPL.
25	*
26	* You may elect to license modified versions of this file under the
27	* terms and conditions of either the GPL or the CDDL or both.
28	*
29	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
30	* Clara, CA 95054 USA or visit http://www.sun.com if you need
31	* additional information or have any questions.
32	*/
33
34
35	/*******************************************************************************
36	* Header Files *
37	*******************************************************************************/
38	#include <iprt/semaphore.h>
39	#include "internal/iprt.h"
40
41	#include <iprt/asm.h>
42	#include <iprt/assert.h>
43	#include <iprt/critsect.h>
44	#include <iprt/err.h>
45	#include <iprt/lockvalidator.h>
46	#include <iprt/mem.h>
47	#include <iprt/time.h>
48	#include <iprt/thread.h>
49
50	#include "internal/magics.h"
51	#include "internal/strict.h"
52
53
54	/*******************************************************************************
55	* Structures and Typedefs *
56	*******************************************************************************/
57
58	/** Internal representation of a Read-Write semaphore for the
59	* Generic implementation. */
60	struct RTSEMRWINTERNAL
61	{
62	/** The usual magic. (RTSEMRW_MAGIC) */
63	uint32_t u32Magic;
64	/* Alignment padding. */
65	uint32_t u32Padding;
66	/** This critical section serializes the access to and updating of the structure members. */
67	RTCRITSECT CritSect;
68	/** The current number of reads. (pure read recursion counts too) */
69	uint32_t cReads;
70	/** The current number of writes. (recursion counts too) */
71	uint32_t cWrites;
72	/** Number of read recursions by the writer. */
73	uint32_t cWriterReads;
74	/** Number of writers waiting. */
75	uint32_t cWritesWaiting;
76	/** The write owner of the lock. */
77	RTNATIVETHREAD hWriter;
78	/** The handle of the event object on which the waiting readers block. (manual reset). */
79	RTSEMEVENTMULTI ReadEvent;
80	/** The handle of the event object on which the waiting writers block. (automatic reset). */
81	RTSEMEVENT WriteEvent;
82	/** Need to reset ReadEvent. */
83	bool fNeedResetReadEvent;
84	#ifdef RTSEMRW_STRICT
85	/** The validator record for the writer. */
86	RTLOCKVALRECEXCL ValidatorWrite;
87	/** The validator record for the readers. */
88	RTLOCKVALRECSHRD ValidatorRead;
89	#endif
90	};
91
92
93
94	#undef RTSemRWCreate
95	RTDECL(int) RTSemRWCreate(PRTSEMRW phRWSem)
96	{
97	return RTSemRWCreateEx(phRWSem, 0 /fFlags/, NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, "RTSemRW");
98	}
99	RT_EXPORT_SYMBOL(RTSemRWCreate);
100
101
102	RTDECL(int) RTSemRWCreateEx(PRTSEMRW phRWSem, uint32_t fFlags,
103	RTLOCKVALCLASS hClass, uint32_t uSubClass, const char *pszNameFmt, ...)
104	{
105	AssertReturn(!(fFlags & ~RTSEMRW_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
106
107	/*
108	* Allocate memory.
109	*/
110	int rc;
111	struct RTSEMRWINTERNAL pThis = (struct RTSEMRWINTERNAL )RTMemAlloc(sizeof(struct RTSEMRWINTERNAL));
112	if (pThis)
113	{
114	/*
115	* Create the semaphores.
116	*/
117	rc = RTSemEventCreateEx(&pThis->WriteEvent, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
118	if (RT_SUCCESS(rc))
119	{
120	rc = RTSemEventMultiCreateEx(&pThis->ReadEvent, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
121	if (RT_SUCCESS(rc))
122	{
123	rc = RTCritSectInitEx(&pThis->CritSect, RTCRITSECT_FLAGS_NO_LOCK_VAL,
124	NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, NULL);
125	if (RT_SUCCESS(rc))
126	{
127	/*
128	* Signal the read semaphore and initialize other variables.
129	*/
130	rc = RTSemEventMultiSignal(pThis->ReadEvent);
131	if (RT_SUCCESS(rc))
132	{
133	pThis->u32Padding = UINT32_C(0xa5a55a5a);
134	pThis->cReads = 0;
135	pThis->cWrites = 0;
136	pThis->cWriterReads = 0;
137	pThis->cWritesWaiting = 0;
138	pThis->hWriter = NIL_RTNATIVETHREAD;
139	pThis->fNeedResetReadEvent = true;
140	pThis->u32Magic = RTSEMRW_MAGIC;
141	#ifdef RTSEMRW_STRICT
142	bool const fLVEnabled = !(fFlags & RTSEMRW_FLAGS_NO_LOCK_VAL);
143	if (!pszNameFmt)
144	{
145	static uint32_t volatile s_iSemRWAnon = 0;
146	uint32_t i = ASMAtomicIncU32(&s_iSemRWAnon) - 1;
147	RTLockValidatorRecExclInit(&pThis->ValidatorWrite, hClass, uSubClass, pThis,
148	fLVEnabled, "RTSemRW-%u", i);
149	RTLockValidatorRecSharedInit(&pThis->ValidatorRead, hClass, uSubClass, pThis,
150	false /fSignaller/, fLVEnabled, "RTSemRW-%u", i);
151	}
152	else
153	{
154	va_list va;
155	va_start(va, pszNameFmt);
156	RTLockValidatorRecExclInitV(&pThis->ValidatorWrite, hClass, uSubClass, pThis,
157	fLVEnabled, pszNameFmt, va);
158	va_end(va);
159	va_start(va, pszNameFmt);
160	RTLockValidatorRecSharedInitV(&pThis->ValidatorRead, hClass, uSubClass, pThis,
161	false /fSignaller/, fLVEnabled, pszNameFmt, va);
162	va_end(va);
163	}
164	RTLockValidatorRecMakeSiblings(&pThis->ValidatorWrite.Core, &pThis->ValidatorRead.Core);
165	#endif
166	*phRWSem = pThis;
167	return VINF_SUCCESS;
168	}
169	RTCritSectDelete(&pThis->CritSect);
170	}
171	RTSemEventMultiDestroy(pThis->ReadEvent);
172	}
173	RTSemEventDestroy(pThis->WriteEvent);
174	}
175	RTMemFree(pThis);
176	}
177	else
178	rc = VERR_NO_MEMORY;
179
180	return rc;
181	}
182	RT_EXPORT_SYMBOL(RTSemRWCreate);
183
184
185	RTDECL(int) RTSemRWDestroy(RTSEMRW hRWSem)
186	{
187	struct RTSEMRWINTERNAL *pThis = hRWSem;
188
189	/*
190	* Validate handle.
191	*/
192	if (pThis == NIL_RTSEMRW)
193	return VINF_SUCCESS;
194	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
195	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
196
197	/*
198	* Check if busy.
199	*/
200	int rc = RTCritSectTryEnter(&pThis->CritSect);
201	if (RT_SUCCESS(rc))
202	{
203	if (!pThis->cReads && !pThis->cWrites)
204	{
205	/*
206	* Make it invalid and unusable.
207	*/
208	ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMRW_MAGIC);
209	pThis->cReads = ~0;
210
211	/*
212	* Do actual cleanup. None of these can now fail.
213	*/
214	rc = RTSemEventMultiDestroy(pThis->ReadEvent);
215	AssertMsgRC(rc, ("RTSemEventMultiDestroy failed! rc=%Rrc\n", rc));
216	pThis->ReadEvent = NIL_RTSEMEVENTMULTI;
217
218	rc = RTSemEventDestroy(pThis->WriteEvent);
219	AssertMsgRC(rc, ("RTSemEventDestroy failed! rc=%Rrc\n", rc));
220	pThis->WriteEvent = NIL_RTSEMEVENT;
221
222	RTCritSectLeave(&pThis->CritSect);
223	rc = RTCritSectDelete(&pThis->CritSect);
224	AssertMsgRC(rc, ("RTCritSectDelete failed! rc=%Rrc\n", rc));
225
226	#ifdef RTSEMRW_STRICT
227	RTLockValidatorRecSharedDelete(&pThis->ValidatorRead);
228	RTLockValidatorRecExclDelete(&pThis->ValidatorWrite);
229	#endif
230	RTMemFree(pThis);
231	rc = VINF_SUCCESS;
232	}
233	else
234	{
235	rc = VERR_SEM_BUSY;
236	RTCritSectLeave(&pThis->CritSect);
237	}
238	}
239	else
240	{
241	AssertMsgRC(rc, ("RTCritSectTryEnter failed! rc=%Rrc\n", rc));
242	rc = VERR_SEM_BUSY;
243	}
244
245	return rc;
246	}
247	RT_EXPORT_SYMBOL(RTSemRWDestroy);
248
249
250	RTDECL(uint32_t) RTSemRWSetSubClass(RTSEMRW hRWSem, uint32_t uSubClass)
251	{
252	#ifdef RTSEMRW_STRICT
253	/*
254	* Validate handle.
255	*/
256	struct RTSEMRWINTERNAL *pThis = hRWSem;
257	AssertPtrReturn(pThis, RTLOCKVAL_SUB_CLASS_INVALID);
258	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, RTLOCKVAL_SUB_CLASS_INVALID);
259
260	RTLockValidatorRecSharedSetSubClass(&pThis->ValidatorRead, uSubClass);
261	return RTLockValidatorRecExclSetSubClass(&pThis->ValidatorWrite, uSubClass);
262	#else
263	return RTLOCKVAL_SUB_CLASS_INVALID;
264	#endif
265	}
266	RT_EXPORT_SYMBOL(RTSemRWSetSubClass);
267
268
269	DECL_FORCE_INLINE(int) rtSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
270	{
271	/*
272	* Validate handle.
273	*/
274	struct RTSEMRWINTERNAL *pThis = hRWSem;
275	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
276	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
277
278	RTMSINTERVAL cMilliesInitial = cMillies;
279	uint64_t tsStart = 0;
280	if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
281	tsStart = RTTimeNanoTS();
282
283	#ifdef RTSEMRW_STRICT
284	RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt();
285	if (cMillies > 0)
286	{
287	int rc9;
288	if (pThis->hWriter != NIL_RTTHREAD && pThis->hWriter == RTThreadNativeSelf())
289	rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
290	else
291	rc9 = RTLockValidatorRecSharedCheckOrder(&pThis->ValidatorRead, hThreadSelf, pSrcPos, cMillies);
292	if (RT_FAILURE(rc9))
293	return rc9;
294	}
295	#endif
296
297	/*
298	* Take critsect.
299	*/
300	int rc = RTCritSectEnter(&pThis->CritSect);
301	if (RT_FAILURE(rc))
302	{
303	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
304	return rc;
305	}
306
307	/*
308	* Check if the state of affairs allows read access.
309	* Do not block further readers if there is a writer waiting, as
310	* that will break/deadlock reader recursion.
311	*/
312	if ( pThis->hWriter == NIL_RTNATIVETHREAD
313	#if 0
314	&& ( !pThis->cWritesWaiting
315	\|\| pThis->cReads)
316	#endif
317	)
318	{
319	pThis->cReads++;
320	Assert(pThis->cReads > 0);
321	#ifdef RTSEMRW_STRICT
322	RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
323	#endif
324
325	RTCritSectLeave(&pThis->CritSect);
326	return VINF_SUCCESS;
327	}
328
329	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
330	if (pThis->hWriter == hNativeSelf)
331	{
332	#ifdef RTSEMRW_STRICT
333	int rc9 = RTLockValidatorRecExclRecursionMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core, pSrcPos);
334	if (RT_FAILURE(rc9))
335	{
336	RTCritSectLeave(&pThis->CritSect);
337	return rc9;
338	}
339	#endif
340
341	pThis->cWriterReads++;
342	Assert(pThis->cWriterReads > 0);
343
344	RTCritSectLeave(&pThis->CritSect);
345	return VINF_SUCCESS;
346	}
347
348	RTCritSectLeave(&pThis->CritSect);
349
350	/*
351	* Wait till it's ready for reading.
352	*/
353	if (cMillies == 0)
354	return VERR_TIMEOUT;
355
356	#ifndef RTSEMRW_STRICT
357	RTTHREAD hThreadSelf = RTThreadSelf();
358	#endif
359	for (;;)
360	{
361	if (cMillies != RT_INDEFINITE_WAIT)
362	{
363	int64_t tsDelta = RTTimeNanoTS() - tsStart;
364	if (tsDelta >= 1000000)
365	{
366	tsDelta /= 1000000;
367	if ((uint64_t)tsDelta < cMilliesInitial)
368	cMilliesInitial = (RTMSINTERVAL)tsDelta;
369	else
370	cMilliesInitial = 1;
371	}
372	}
373	#ifdef RTSEMRW_STRICT
374	rc = RTLockValidatorRecSharedCheckBlocking(&pThis->ValidatorRead, hThreadSelf, pSrcPos, true,
375	cMillies, RTTHREADSTATE_RW_READ, false);
376	if (RT_FAILURE(rc))
377	break;
378	#else
379	RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_READ, false);
380	#endif
381	int rcWait;
382	if (fInterruptible)
383	rcWait = rc = RTSemEventMultiWaitNoResume(pThis->ReadEvent, cMillies);
384	else
385	rcWait = rc = RTSemEventMultiWait(pThis->ReadEvent, cMillies);
386	RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_READ);
387	if (RT_FAILURE(rc) && rc != VERR_TIMEOUT) /* handle timeout below */
388	{
389	AssertMsgRC(rc, ("RTSemEventMultiWait failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
390	break;
391	}
392
393	if (pThis->u32Magic != RTSEMRW_MAGIC)
394	{
395	rc = VERR_SEM_DESTROYED;
396	break;
397	}
398
399	/*
400	* Re-take critsect and repeate the check we did before the loop.
401	*/
402	rc = RTCritSectEnter(&pThis->CritSect);
403	if (RT_FAILURE(rc))
404	{
405	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
406	break;
407	}
408
409	if ( pThis->hWriter == NIL_RTNATIVETHREAD
410	#if 0
411	&& ( !pThis->cWritesWaiting
412	\|\| pThis->cReads)
413	#endif
414	)
415	{
416	pThis->cReads++;
417	Assert(pThis->cReads > 0);
418	#ifdef RTSEMRW_STRICT
419	RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
420	#endif
421
422	RTCritSectLeave(&pThis->CritSect);
423	return VINF_SUCCESS;
424	}
425
426	RTCritSectLeave(&pThis->CritSect);
427
428	/*
429	* Quit if the wait already timed out.
430	*/
431	if (rcWait == VERR_TIMEOUT)
432	{
433	rc = VERR_TIMEOUT;
434	break;
435	}
436	}
437
438	/* failed */
439	return rc;
440	}
441
442
443	#undef RTSemRWRequestRead
444	RTDECL(int) RTSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
445	{
446	#ifndef RTSEMRW_STRICT
447	return rtSemRWRequestRead(hRWSem, cMillies, false, NULL);
448	#else
449	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
450	return rtSemRWRequestRead(hRWSem, cMillies, false, &SrcPos);
451	#endif
452	}
453	RT_EXPORT_SYMBOL(RTSemRWRequestRead);
454
455
456	RTDECL(int) RTSemRWRequestReadDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
457	{
458	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
459	return rtSemRWRequestRead(hRWSem, cMillies, false, &SrcPos);
460	}
461	RT_EXPORT_SYMBOL(RTSemRWRequestReadDebug);
462
463
464	#undef RTSemRWRequestReadNoResume
465	RTDECL(int) RTSemRWRequestReadNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
466	{
467	#ifndef RTSEMRW_STRICT
468	return rtSemRWRequestRead(hRWSem, cMillies, true, NULL);
469	#else
470	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
471	return rtSemRWRequestRead(hRWSem, cMillies, true, &SrcPos);
472	#endif
473	}
474	RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResume);
475
476
477	RTDECL(int) RTSemRWRequestReadNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
478	{
479	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
480	return rtSemRWRequestRead(hRWSem, cMillies, true, &SrcPos);
481	}
482	RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResumeDebug);
483
484
485	RTDECL(int) RTSemRWReleaseRead(RTSEMRW hRWSem)
486	{
487	struct RTSEMRWINTERNAL *pThis = hRWSem;
488
489	/*
490	* Validate handle.
491	*/
492	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
493	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
494
495	/*
496	* Take critsect.
497	*/
498	int rc = RTCritSectEnter(&pThis->CritSect);
499	if (RT_SUCCESS(rc))
500	{
501	if (pThis->hWriter == NIL_RTNATIVETHREAD)
502	{
503	#ifdef RTSEMRW_STRICT
504	rc = RTLockValidatorRecSharedCheckAndRelease(&pThis->ValidatorRead, NIL_RTTHREAD);
505	if (RT_SUCCESS(rc))
506	#endif
507	{
508	if (RT_LIKELY(pThis->cReads > 0))
509	{
510	pThis->cReads--;
511
512	/* Kick off a writer if appropriate. */
513	if ( pThis->cWritesWaiting > 0
514	&& !pThis->cReads)
515	{
516	rc = RTSemEventSignal(pThis->WriteEvent);
517	AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", hRWSem, rc));
518	}
519	}
520	else
521	{
522	AssertFailed();
523	rc = VERR_NOT_OWNER;
524	}
525	}
526	}
527	else
528	{
529	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
530	if (pThis->hWriter == hNativeSelf)
531	{
532	if (pThis->cWriterReads > 0)
533	{
534	#ifdef RTSEMRW_STRICT
535	rc = RTLockValidatorRecExclUnwindMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core);
536	if (RT_SUCCESS(rc))
537	#endif
538	{
539	pThis->cWriterReads--;
540	}
541	}
542	else
543	{
544	AssertFailed();
545	rc = VERR_NOT_OWNER;
546	}
547	}
548	else
549	{
550	AssertFailed();
551	rc = VERR_NOT_OWNER;
552	}
553	}
554
555	RTCritSectLeave(&pThis->CritSect);
556	}
557	else
558	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
559
560	return rc;
561	}
562	RT_EXPORT_SYMBOL(RTSemRWReleaseRead);
563
564
565	DECL_FORCE_INLINE(int) rtSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
566	{
567	/*
568	* Validate handle.
569	*/
570	struct RTSEMRWINTERNAL *pThis = hRWSem;
571	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
572	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
573
574	RTMSINTERVAL cMilliesInitial = cMillies;
575	uint64_t tsStart = 0;
576	if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
577	tsStart = RTTimeNanoTS();
578
579	#ifdef RTSEMRW_STRICT
580	RTTHREAD hThreadSelf = NIL_RTTHREAD;
581	if (cMillies)
582	{
583	hThreadSelf = RTThreadSelfAutoAdopt();
584	int rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
585	if (RT_FAILURE(rc9))
586	return rc9;
587	}
588	#endif
589
590	/*
591	* Take critsect.
592	*/
593	int rc = RTCritSectEnter(&pThis->CritSect);
594	if (RT_FAILURE(rc))
595	{
596	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
597	return rc;
598	}
599
600	/*
601	* Check if the state of affairs allows write access.
602	*/
603	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
604	if ( !pThis->cReads
605	&& ( ( !pThis->cWrites
606	&& ( !pThis->cWritesWaiting /* play fair if we can wait */
607	\|\| !cMillies)
608	)
609	\|\| pThis->hWriter == hNativeSelf
610	)
611	)
612	{
613	/*
614	* Reset the reader event semaphore if necessary.
615	*/
616	if (pThis->fNeedResetReadEvent)
617	{
618	pThis->fNeedResetReadEvent = false;
619	rc = RTSemEventMultiReset(pThis->ReadEvent);
620	AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", hRWSem, rc));
621	}
622
623	pThis->cWrites++;
624	pThis->hWriter = hNativeSelf;
625	#ifdef RTSEMRW_STRICT
626	RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, pThis->cWrites == 1);
627	#endif
628	RTCritSectLeave(&pThis->CritSect);
629	return VINF_SUCCESS;
630	}
631
632	/*
633	* Signal writer presence.
634	*/
635	if (cMillies != 0)
636	pThis->cWritesWaiting++;
637
638	RTCritSectLeave(&pThis->CritSect);
639
640	/*
641	* Wait till it's ready for writing.
642	*/
643	if (cMillies == 0)
644	return VERR_TIMEOUT;
645
646	#ifndef RTSEMRW_STRICT
647	RTTHREAD hThreadSelf = RTThreadSelf();
648	#endif
649	for (;;)
650	{
651	if (cMillies != RT_INDEFINITE_WAIT)
652	{
653	int64_t tsDelta = RTTimeNanoTS() - tsStart;
654	if (tsDelta >= 1000000)
655	{
656	tsDelta /= 1000000;
657	if ((uint64_t)tsDelta < cMilliesInitial)
658	cMilliesInitial = (RTMSINTERVAL)tsDelta;
659	else
660	cMilliesInitial = 1;
661	}
662	}
663
664	#ifdef RTSEMRW_STRICT
665	rc = RTLockValidatorRecExclCheckBlocking(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true,
666	cMillies, RTTHREADSTATE_RW_WRITE, false);
667	if (RT_FAILURE(rc))
668	break;
669	#else
670	RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_WRITE, false);
671	#endif
672	int rcWait;
673	if (fInterruptible)
674	rcWait = rc = RTSemEventWaitNoResume(pThis->WriteEvent, cMillies);
675	else
676	rcWait = rc = RTSemEventWait(pThis->WriteEvent, cMillies);
677	RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_WRITE);
678	if (RT_UNLIKELY(RT_FAILURE_NP(rc) && rc != VERR_TIMEOUT)) /* timeouts are handled below */
679	{
680	AssertMsgRC(rc, ("RTSemEventWait failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
681	break;
682	}
683
684	if (RT_UNLIKELY(pThis->u32Magic != RTSEMRW_MAGIC))
685	{
686	rc = VERR_SEM_DESTROYED;
687	break;
688	}
689
690	/*
691	* Re-take critsect and repeate the check we did prior to this loop.
692	*/
693	rc = RTCritSectEnter(&pThis->CritSect);
694	if (RT_FAILURE(rc))
695	{
696	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
697	break;
698	}
699
700	if (!pThis->cReads && (!pThis->cWrites \|\| pThis->hWriter == hNativeSelf))
701	{
702	/*
703	* Reset the reader event semaphore if necessary.
704	*/
705	if (pThis->fNeedResetReadEvent)
706	{
707	pThis->fNeedResetReadEvent = false;
708	rc = RTSemEventMultiReset(pThis->ReadEvent);
709	AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", hRWSem, rc));
710	}
711
712	pThis->cWrites++;
713	pThis->hWriter = hNativeSelf;
714	pThis->cWritesWaiting--;
715	#ifdef RTSEMRW_STRICT
716	RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true);
717	#endif
718
719	RTCritSectLeave(&pThis->CritSect);
720	return VINF_SUCCESS;
721	}
722
723	RTCritSectLeave(&pThis->CritSect);
724
725	/*
726	* Quit if the wait already timed out.
727	*/
728	if (rcWait == VERR_TIMEOUT)
729	{
730	rc = VERR_TIMEOUT;
731	break;
732	}
733	}
734
735	/*
736	* Timeout/error case, clean up.
737	*/
738	if (pThis->u32Magic == RTSEMRW_MAGIC)
739	{
740	RTCritSectEnter(&pThis->CritSect);
741	/* Adjust this counter, whether we got the critsect or not. */
742	pThis->cWritesWaiting--;
743	RTCritSectLeave(&pThis->CritSect);
744	}
745	return rc;
746	}
747
748
749	#undef RTSemRWRequestWrite
750	RTDECL(int) RTSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
751	{
752	#ifndef RTSEMRW_STRICT
753	return rtSemRWRequestWrite(hRWSem, cMillies, false, NULL);
754	#else
755	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
756	return rtSemRWRequestWrite(hRWSem, cMillies, false, &SrcPos);
757	#endif
758	}
759	RT_EXPORT_SYMBOL(RTSemRWRequestWrite);
760
761
762	RTDECL(int) RTSemRWRequestWriteDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
763	{
764	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
765	return rtSemRWRequestWrite(hRWSem, cMillies, false, &SrcPos);
766	}
767	RT_EXPORT_SYMBOL(RTSemRWRequestWriteDebug);
768
769
770	#undef RTSemRWRequestWriteNoResume
771	RTDECL(int) RTSemRWRequestWriteNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
772	{
773	#ifndef RTSEMRW_STRICT
774	return rtSemRWRequestWrite(hRWSem, cMillies, true, NULL);
775	#else
776	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
777	return rtSemRWRequestWrite(hRWSem, cMillies, true, &SrcPos);
778	#endif
779	}
780	RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResume);
781
782
783	RTDECL(int) RTSemRWRequestWriteNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
784	{
785	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
786	return rtSemRWRequestWrite(hRWSem, cMillies, true, &SrcPos);
787	}
788	RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResumeDebug);
789
790
791	RTDECL(int) RTSemRWReleaseWrite(RTSEMRW hRWSem)
792	{
793
794	/*
795	* Validate handle.
796	*/
797	struct RTSEMRWINTERNAL *pThis = hRWSem;
798	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
799	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
800
801	/*
802	* Take critsect.
803	*/
804	int rc = RTCritSectEnter(&pThis->CritSect);
805	AssertRCReturn(rc, rc);
806
807	/*
808	* Check if owner.
809	*/
810	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
811	if (pThis->hWriter != hNativeSelf)
812	{
813	RTCritSectLeave(&pThis->CritSect);
814	AssertMsgFailed(("Not read-write owner of rwsem %p.\n", hRWSem));
815	return VERR_NOT_OWNER;
816	}
817
818	#ifdef RTSEMRW_STRICT
819	if (pThis->cWrites > 1 \|\| !pThis->cWriterReads) /* don't check+release if VERR_WRONG_ORDER */
820	{
821	int rc9 = RTLockValidatorRecExclReleaseOwner(&pThis->ValidatorWrite, pThis->cWrites == 1);
822	if (RT_FAILURE(rc9))
823	{
824	RTCritSectLeave(&pThis->CritSect);
825	return rc9;
826	}
827	}
828	#endif
829
830	/*
831	* Release ownership and remove ourselves from the writers count.
832	*/
833	Assert(pThis->cWrites > 0);
834	pThis->cWrites--;
835	if (!pThis->cWrites)
836	{
837	if (RT_UNLIKELY(pThis->cWriterReads > 0))
838	{
839	pThis->cWrites++;
840	RTCritSectLeave(&pThis->CritSect);
841	AssertMsgFailed(("All recursive read locks need to be released prior to the final write lock! (%p)n\n", pThis));
842	return VERR_WRONG_ORDER;
843	}
844
845	pThis->hWriter = NIL_RTNATIVETHREAD;
846	}
847
848	/*
849	* Release the readers if no more writers waiting, otherwise the writers.
850	*/
851	if (!pThis->cWritesWaiting)
852	{
853	rc = RTSemEventMultiSignal(pThis->ReadEvent);
854	AssertMsgRC(rc, ("RTSemEventMultiSignal failed for rwsem %p, rc=%Rrc.\n", hRWSem, rc));
855	pThis->fNeedResetReadEvent = true;
856	}
857	else
858	{
859	rc = RTSemEventSignal(pThis->WriteEvent);
860	AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", hRWSem, rc));
861	}
862	RTCritSectLeave(&pThis->CritSect);
863
864	return rc;
865	}
866	RT_EXPORT_SYMBOL(RTSemRWReleaseWrite);
867
868
869	RTDECL(bool) RTSemRWIsWriteOwner(RTSEMRW hRWSem)
870	{
871	/*
872	* Validate handle.
873	*/
874	struct RTSEMRWINTERNAL *pThis = hRWSem;
875	AssertPtrReturn(pThis, false);
876	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, false);
877
878	/*
879	* Check ownership.
880	*/
881	RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
882	RTNATIVETHREAD hWriter;
883	ASMAtomicUoReadHandle(&pThis->hWriter, &hWriter);
884	return hWriter == hNativeSelf;
885	}
886	RT_EXPORT_SYMBOL(RTSemRWIsWriteOwner);
887
888
889	RTDECL(bool) RTSemRWIsReadOwner(RTSEMRW hRWSem, bool fWannaHear)
890	{
891	/*
892	* Validate handle.
893	*/
894	struct RTSEMRWINTERNAL *pThis = hRWSem;
895	AssertPtrReturn(pThis, false);
896	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, false);
897
898	/*
899	* Check write ownership. The writer is also a valid reader.
900	*/
901	RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
902	RTNATIVETHREAD hWriter;
903	ASMAtomicUoReadHandle(&pThis->hWriter, &hWriter);
904	if (hWriter == hNativeSelf)
905	return true;
906	if (hWriter != NIL_RTNATIVETHREAD)
907	return false;
908
909	#ifdef RTSEMRW_STRICT
910	/*
911	* Ask the lock validator.
912	*/
913	return RTLockValidatorRecSharedIsOwner(&pThis->ValidatorRead, NIL_RTTHREAD);
914	#else
915	/*
916	* If there are no reads we cannot be one of them... But if there are we
917	* cannot know and can only return what the caller want to hear.
918	*/
919	if (pThis->cReads == 0)
920	return false;
921	return fWannaHear;
922	#endif
923	}
924	RT_EXPORT_SYMBOL(RTSemRWIsReadOwner);
925
926
927	RTDECL(uint32_t) RTSemRWGetWriteRecursion(RTSEMRW hRWSem)
928	{
929	struct RTSEMRWINTERNAL *pThis = hRWSem;
930
931	/*
932	* Validate handle.
933	*/
934	AssertPtrReturn(pThis, 0);
935	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, 0);
936
937	/*
938	* Return the requested data.
939	*/
940	return pThis->cWrites;
941	}
942	RT_EXPORT_SYMBOL(RTSemRWGetWriteRecursion);
943
944
945	RTDECL(uint32_t) RTSemRWGetWriterReadRecursion(RTSEMRW hRWSem)
946	{
947	struct RTSEMRWINTERNAL *pThis = hRWSem;
948
949	/*
950	* Validate handle.
951	*/
952	AssertPtrReturn(pThis, 0);
953	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, 0);
954
955	/*
956	* Return the requested data.
957	*/
958	return pThis->cWriterReads;
959	}
960	RT_EXPORT_SYMBOL(RTSemRWGetWriterReadRecursion);
961
962
963	RTDECL(uint32_t) RTSemRWGetReadCount(RTSEMRW hRWSem)
964	{
965	/*
966	* Validate input.
967	*/
968	struct RTSEMRWINTERNAL *pThis = hRWSem;
969	AssertPtrReturn(pThis, 0);
970	AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC,
971	("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
972	0);
973
974	/*
975	* Return the requested data.
976	*/
977	return pThis->cReads;
978	}
979	RT_EXPORT_SYMBOL(RTSemRWGetReadCount);
980

Note: See TracBrowser for help on using the repository browser.

source: vbox/trunk/src/VBox/Runtime/generic/semrw-generic.cpp@ 27124

Download in other formats: