semrw-generic.cpp@ 25707

Last change on this file since 25707 was 25707, checked in by vboxsync, 15 years ago
iprt: Added RTSemRWCreateEx and RTSemRWSetSubClass. Updated tstRTLockValidator with a test of the SemRW lock order validation.
Property svn:eol-style set to `native` Property svn:keywords set to `Id`
File size: 27.2 KB

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1	/* $Id: semrw-generic.cpp 25707 2010-01-11 10:02:03Z 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 = RTSemEventCreate(&pThis->WriteEvent);
118	if (RT_SUCCESS(rc))
119	{
120	rc = RTSemEventMultiCreate(&pThis->ReadEvent);
121	if (RT_SUCCESS(rc))
122	{
123	rc = RTCritSectInit(&pThis->CritSect);
124	if (RT_SUCCESS(rc))
125	{
126	/*
127	* Signal the read semaphore and initialize other variables.
128	*/
129	rc = RTSemEventMultiSignal(pThis->ReadEvent);
130	if (RT_SUCCESS(rc))
131	{
132	pThis->u32Padding = UINT32_C(0xa5a55a5a);
133	pThis->cReads = 0;
134	pThis->cWrites = 0;
135	pThis->cWriterReads = 0;
136	pThis->cWritesWaiting = 0;
137	pThis->hWriter = NIL_RTNATIVETHREAD;
138	pThis->fNeedResetReadEvent = true;
139	pThis->u32Magic = RTSEMRW_MAGIC;
140	#ifdef RTSEMRW_STRICT
141	bool const fLVEnabled = !(fFlags & RTSEMRW_FLAGS_NO_LOCK_VAL);
142	va_list va;
143	va_start(va, pszNameFmt);
144	RTLockValidatorRecExclInit(&pThis->ValidatorWrite, hClass, uSubClass, pThis, fLVEnabled, pszNameFmt);
145	va_end(va);
146	va_start(va, pszNameFmt);
147	RTLockValidatorRecSharedInit(&pThis->ValidatorRead, hClass, uSubClass, pThis, false /fSignaller/,
148	fLVEnabled, pszNameFmt);
149	va_end(va);
150	RTLockValidatorRecMakeSiblings(&pThis->ValidatorWrite.Core, &pThis->ValidatorRead.Core);
151	#endif
152	*phRWSem = pThis;
153	return VINF_SUCCESS;
154	}
155	RTCritSectDelete(&pThis->CritSect);
156	}
157	RTSemEventMultiDestroy(pThis->ReadEvent);
158	}
159	RTSemEventDestroy(pThis->WriteEvent);
160	}
161	RTMemFree(pThis);
162	}
163	else
164	rc = VERR_NO_MEMORY;
165
166	return rc;
167	}
168	RT_EXPORT_SYMBOL(RTSemRWCreate);
169
170
171	RTDECL(int) RTSemRWDestroy(RTSEMRW RWSem)
172	{
173	struct RTSEMRWINTERNAL *pThis = RWSem;
174
175	/*
176	* Validate handle.
177	*/
178	if (pThis == NIL_RTSEMRW)
179	return VINF_SUCCESS;
180	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
181	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
182
183	/*
184	* Check if busy.
185	*/
186	int rc = RTCritSectTryEnter(&pThis->CritSect);
187	if (RT_SUCCESS(rc))
188	{
189	if (!pThis->cReads && !pThis->cWrites)
190	{
191	/*
192	* Make it invalid and unusable.
193	*/
194	ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMRW_MAGIC);
195	pThis->cReads = ~0;
196
197	/*
198	* Do actual cleanup. None of these can now fail.
199	*/
200	rc = RTSemEventMultiDestroy(pThis->ReadEvent);
201	AssertMsgRC(rc, ("RTSemEventMultiDestroy failed! rc=%Rrc\n", rc));
202	pThis->ReadEvent = NIL_RTSEMEVENTMULTI;
203
204	rc = RTSemEventDestroy(pThis->WriteEvent);
205	AssertMsgRC(rc, ("RTSemEventDestroy failed! rc=%Rrc\n", rc));
206	pThis->WriteEvent = NIL_RTSEMEVENT;
207
208	RTCritSectLeave(&pThis->CritSect);
209	rc = RTCritSectDelete(&pThis->CritSect);
210	AssertMsgRC(rc, ("RTCritSectDelete failed! rc=%Rrc\n", rc));
211
212	#ifdef RTSEMRW_STRICT
213	RTLockValidatorRecSharedDelete(&pThis->ValidatorRead);
214	RTLockValidatorRecExclDelete(&pThis->ValidatorWrite);
215	#endif
216	RTMemFree(pThis);
217	rc = VINF_SUCCESS;
218	}
219	else
220	{
221	rc = VERR_SEM_BUSY;
222	RTCritSectLeave(&pThis->CritSect);
223	}
224	}
225	else
226	{
227	AssertMsgRC(rc, ("RTCritSectTryEnter failed! rc=%Rrc\n", rc));
228	rc = VERR_SEM_BUSY;
229	}
230
231	return rc;
232	}
233	RT_EXPORT_SYMBOL(RTSemRWDestroy);
234
235
236	RTDECL(uint32_t) RTSemRWSetSubClass(RTSEMRW hRWSem, uint32_t uSubClass)
237	{
238	#ifdef RTSEMRW_STRICT
239	/*
240	* Validate handle.
241	*/
242	struct RTSEMRWINTERNAL *pThis = hRWSem;
243	AssertPtrReturn(pThis, RTLOCKVAL_SUB_CLASS_INVALID);
244	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, RTLOCKVAL_SUB_CLASS_INVALID);
245
246	RTLockValidatorRecSharedSetSubClass(&pThis->ValidatorRead, uSubClass);
247	return RTLockValidatorRecExclSetSubClass(&pThis->ValidatorWrite, uSubClass);
248	#else
249	return RTLOCKVAL_SUB_CLASS_INVALID;
250	#endif
251	}
252	RT_EXPORT_SYMBOL(RTSemRWSetSubClass);
253
254
255	DECL_FORCE_INLINE(int) rtSemRWRequestRead(RTSEMRW RWSem, unsigned cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
256	{
257	/*
258	* Validate handle.
259	*/
260	struct RTSEMRWINTERNAL *pThis = RWSem;
261	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
262	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
263
264	unsigned cMilliesInitial = cMillies;
265	uint64_t tsStart = 0;
266	if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
267	tsStart = RTTimeNanoTS();
268
269	#ifdef RTSEMRW_STRICT
270	RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt();
271	if (cMillies > 0)
272	{
273	int rc9 = RTLockValidatorRecSharedCheckOrder(&pThis->ValidatorRead, hThreadSelf, pSrcPos, cMillies);
274	if (RT_FAILURE(rc9))
275	return rc9;
276	}
277	#endif
278
279	/*
280	* Take critsect.
281	*/
282	int rc = RTCritSectEnter(&pThis->CritSect);
283	if (RT_FAILURE(rc))
284	{
285	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", RWSem, rc));
286	return rc;
287	}
288
289	/*
290	* Check if the state of affairs allows read access.
291	* Do not block further readers if there is a writer waiting, as
292	* that will break/deadlock reader recursion.
293	*/
294	if ( pThis->hWriter == NIL_RTNATIVETHREAD
295	#if 0
296	&& ( !pThis->cWritesWaiting
297	\|\| pThis->cReads)
298	#endif
299	)
300	{
301	pThis->cReads++;
302	Assert(pThis->cReads > 0);
303	#ifdef RTSEMRW_STRICT
304	RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
305	#endif
306
307	RTCritSectLeave(&pThis->CritSect);
308	return VINF_SUCCESS;
309	}
310
311	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
312	if (pThis->hWriter == hNativeSelf)
313	{
314	#ifdef RTSEMRW_STRICT
315	int rc9 = RTLockValidatorRecExclRecursionMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core, pSrcPos);
316	if (RT_FAILURE(rc9))
317	{
318	RTCritSectLeave(&pThis->CritSect);
319	return rc9;
320	}
321	#endif
322
323	pThis->cWriterReads++;
324	Assert(pThis->cWriterReads > 0);
325
326	RTCritSectLeave(&pThis->CritSect);
327	return VINF_SUCCESS;
328	}
329
330	RTCritSectLeave(&pThis->CritSect);
331
332	/*
333	* Wait till it's ready for reading.
334	*/
335	if (cMillies == 0)
336	return VERR_TIMEOUT;
337
338	#ifndef RTSEMRW_STRICT
339	RTTHREAD hThreadSelf = RTThreadSelf();
340	#endif
341	for (;;)
342	{
343	if (cMillies != RT_INDEFINITE_WAIT)
344	{
345	int64_t tsDelta = RTTimeNanoTS() - tsStart;
346	if (tsDelta >= 1000000)
347	{
348	tsDelta /= 1000000;
349	if ((uint64_t)tsDelta < cMilliesInitial)
350	cMilliesInitial = (unsigned)tsDelta;
351	else
352	cMilliesInitial = 1;
353	}
354	}
355	#ifdef RTSEMRW_STRICT
356	rc = RTLockValidatorRecSharedCheckBlocking(&pThis->ValidatorRead, hThreadSelf, pSrcPos, true,
357	cMillies, RTTHREADSTATE_RW_READ, false);
358	if (RT_FAILURE(rc))
359	break;
360	#else
361	RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_READ, false);
362	#endif
363	int rcWait;
364	if (fInterruptible)
365	rcWait = rc = RTSemEventMultiWaitNoResume(pThis->ReadEvent, cMillies);
366	else
367	rcWait = rc = RTSemEventMultiWait(pThis->ReadEvent, cMillies);
368	RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_READ);
369	if (RT_FAILURE(rc) && rc != VERR_TIMEOUT) /* handle timeout below */
370	{
371	AssertMsgRC(rc, ("RTSemEventMultiWait failed on rwsem %p, rc=%Rrc\n", RWSem, rc));
372	break;
373	}
374
375	if (pThis->u32Magic != RTSEMRW_MAGIC)
376	{
377	rc = VERR_SEM_DESTROYED;
378	break;
379	}
380
381	/*
382	* Re-take critsect and repeate the check we did before the loop.
383	*/
384	rc = RTCritSectEnter(&pThis->CritSect);
385	if (RT_FAILURE(rc))
386	{
387	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", RWSem, rc));
388	break;
389	}
390
391	if ( pThis->hWriter == NIL_RTNATIVETHREAD
392	#if 0
393	&& ( !pThis->cWritesWaiting
394	\|\| pThis->cReads)
395	#endif
396	)
397	{
398	pThis->cReads++;
399	Assert(pThis->cReads > 0);
400	#ifdef RTSEMRW_STRICT
401	RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
402	#endif
403
404	RTCritSectLeave(&pThis->CritSect);
405	return VINF_SUCCESS;
406	}
407
408	RTCritSectLeave(&pThis->CritSect);
409
410	/*
411	* Quit if the wait already timed out.
412	*/
413	if (rcWait == VERR_TIMEOUT)
414	{
415	rc = VERR_TIMEOUT;
416	break;
417	}
418	}
419
420	/* failed */
421	return rc;
422	}
423
424
425	#undef RTSemRWRequestRead
426	RTDECL(int) RTSemRWRequestRead(RTSEMRW RWSem, unsigned cMillies)
427	{
428	#ifndef RTSEMRW_STRICT
429	return rtSemRWRequestRead(RWSem, cMillies, false, NULL);
430	#else
431	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
432	return rtSemRWRequestRead(RWSem, cMillies, false, &SrcPos);
433	#endif
434	}
435	RT_EXPORT_SYMBOL(RTSemRWRequestRead);
436
437
438	RTDECL(int) RTSemRWRequestReadDebug(RTSEMRW RWSem, unsigned cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
439	{
440	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
441	return rtSemRWRequestRead(RWSem, cMillies, false, &SrcPos);
442	}
443	RT_EXPORT_SYMBOL(RTSemRWRequestReadDebug);
444
445
446	#undef RTSemRWRequestReadNoResume
447	RTDECL(int) RTSemRWRequestReadNoResume(RTSEMRW RWSem, unsigned cMillies)
448	{
449	#ifndef RTSEMRW_STRICT
450	return rtSemRWRequestRead(RWSem, cMillies, true, NULL);
451	#else
452	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
453	return rtSemRWRequestRead(RWSem, cMillies, true, &SrcPos);
454	#endif
455	}
456	RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResume);
457
458
459	RTDECL(int) RTSemRWRequestReadNoResumeDebug(RTSEMRW RWSem, unsigned cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
460	{
461	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
462	return rtSemRWRequestRead(RWSem, cMillies, true, &SrcPos);
463	}
464	RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResumeDebug);
465
466
467	RTDECL(int) RTSemRWReleaseRead(RTSEMRW RWSem)
468	{
469	struct RTSEMRWINTERNAL *pThis = RWSem;
470
471	/*
472	* Validate handle.
473	*/
474	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
475	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
476
477	/*
478	* Take critsect.
479	*/
480	int rc = RTCritSectEnter(&pThis->CritSect);
481	if (RT_SUCCESS(rc))
482	{
483	if (pThis->hWriter == NIL_RTNATIVETHREAD)
484	{
485	#ifdef RTSEMRW_STRICT
486	rc = RTLockValidatorRecSharedCheckAndRelease(&pThis->ValidatorRead, NIL_RTTHREAD);
487	if (RT_SUCCESS(rc))
488	#endif
489	{
490	if (RT_LIKELY(pThis->cReads > 0))
491	{
492	pThis->cReads--;
493
494	/* Kick off a writer if appropriate. */
495	if ( pThis->cWritesWaiting > 0
496	&& !pThis->cReads)
497	{
498	rc = RTSemEventSignal(pThis->WriteEvent);
499	AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", RWSem, rc));
500	}
501	}
502	else
503	{
504	AssertFailed();
505	rc = VERR_NOT_OWNER;
506	}
507	}
508	}
509	else
510	{
511	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
512	if (pThis->hWriter == hNativeSelf)
513	{
514	if (pThis->cWriterReads > 0)
515	{
516	#ifdef RTSEMRW_STRICT
517	rc = RTLockValidatorRecExclUnwindMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core);
518	if (RT_SUCCESS(rc))
519	#endif
520	{
521	pThis->cWriterReads--;
522	}
523	}
524	else
525	{
526	AssertFailed();
527	rc = VERR_NOT_OWNER;
528	}
529	}
530	else
531	{
532	AssertFailed();
533	rc = VERR_NOT_OWNER;
534	}
535	}
536
537	RTCritSectLeave(&pThis->CritSect);
538	}
539	else
540	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", RWSem, rc));
541
542	return rc;
543	}
544	RT_EXPORT_SYMBOL(RTSemRWReleaseRead);
545
546
547	DECL_FORCE_INLINE(int) rtSemRWRequestWrite(RTSEMRW RWSem, unsigned cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
548	{
549	/*
550	* Validate handle.
551	*/
552	struct RTSEMRWINTERNAL *pThis = RWSem;
553	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
554	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
555
556	unsigned cMilliesInitial = cMillies;
557	uint64_t tsStart = 0;
558	if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
559	tsStart = RTTimeNanoTS();
560
561	#ifdef RTSEMRW_STRICT
562	RTTHREAD hThreadSelf = NIL_RTTHREAD;
563	if (cMillies)
564	{
565	hThreadSelf = RTThreadSelfAutoAdopt();
566	int rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
567	if (RT_FAILURE(rc9))
568	return rc9;
569	}
570	#endif
571
572	/*
573	* Take critsect.
574	*/
575	int rc = RTCritSectEnter(&pThis->CritSect);
576	if (RT_FAILURE(rc))
577	{
578	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", RWSem, rc));
579	return rc;
580	}
581
582	/*
583	* Check if the state of affairs allows write access.
584	*/
585	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
586	if ( !pThis->cReads
587	&& ( ( !pThis->cWrites
588	&& ( !pThis->cWritesWaiting /* play fair if we can wait */
589	\|\| !cMillies)
590	)
591	\|\| pThis->hWriter == hNativeSelf
592	)
593	)
594	{
595	/*
596	* Reset the reader event semaphore if necessary.
597	*/
598	if (pThis->fNeedResetReadEvent)
599	{
600	pThis->fNeedResetReadEvent = false;
601	rc = RTSemEventMultiReset(pThis->ReadEvent);
602	AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", RWSem, rc));
603	}
604
605	pThis->cWrites++;
606	pThis->hWriter = hNativeSelf;
607	#ifdef RTSEMRW_STRICT
608	RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, pThis->cWrites == 1);
609	#endif
610	RTCritSectLeave(&pThis->CritSect);
611	return VINF_SUCCESS;
612	}
613
614	/*
615	* Signal writer presence.
616	*/
617	if (cMillies != 0)
618	pThis->cWritesWaiting++;
619
620	RTCritSectLeave(&pThis->CritSect);
621
622	/*
623	* Wait till it's ready for writing.
624	*/
625	if (cMillies == 0)
626	return VERR_TIMEOUT;
627
628	#ifndef RTSEMRW_STRICT
629	RTTHREAD hThreadSelf = RTThreadSelf();
630	#endif
631	for (;;)
632	{
633	if (cMillies != RT_INDEFINITE_WAIT)
634	{
635	int64_t tsDelta = RTTimeNanoTS() - tsStart;
636	if (tsDelta >= 1000000)
637	{
638	tsDelta /= 1000000;
639	if ((uint64_t)tsDelta < cMilliesInitial)
640	cMilliesInitial = (unsigned)tsDelta;
641	else
642	cMilliesInitial = 1;
643	}
644	}
645
646	#ifdef RTSEMRW_STRICT
647	rc = RTLockValidatorRecExclCheckBlocking(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true,
648	cMillies, RTTHREADSTATE_RW_WRITE, false);
649	if (RT_FAILURE(rc))
650	break;
651	#else
652	RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_WRITE, false);
653	#endif
654	int rcWait;
655	if (fInterruptible)
656	rcWait = rc = RTSemEventWaitNoResume(pThis->WriteEvent, cMillies);
657	else
658	rcWait = rc = RTSemEventWait(pThis->WriteEvent, cMillies);
659	RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_WRITE);
660	if (RT_UNLIKELY(RT_FAILURE_NP(rc) && rc != VERR_TIMEOUT)) /* timeouts are handled below */
661	{
662	AssertMsgRC(rc, ("RTSemEventWait failed on rwsem %p, rc=%Rrc\n", RWSem, rc));
663	break;
664	}
665
666	if (RT_UNLIKELY(pThis->u32Magic != RTSEMRW_MAGIC))
667	{
668	rc = VERR_SEM_DESTROYED;
669	break;
670	}
671
672	/*
673	* Re-take critsect and repeate the check we did prior to this loop.
674	*/
675	rc = RTCritSectEnter(&pThis->CritSect);
676	if (RT_FAILURE(rc))
677	{
678	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", RWSem, rc));
679	break;
680	}
681
682	if (!pThis->cReads && (!pThis->cWrites \|\| pThis->hWriter == hNativeSelf))
683	{
684	/*
685	* Reset the reader event semaphore if necessary.
686	*/
687	if (pThis->fNeedResetReadEvent)
688	{
689	pThis->fNeedResetReadEvent = false;
690	rc = RTSemEventMultiReset(pThis->ReadEvent);
691	AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", RWSem, rc));
692	}
693
694	pThis->cWrites++;
695	pThis->hWriter = hNativeSelf;
696	pThis->cWritesWaiting--;
697	#ifdef RTSEMRW_STRICT
698	RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true);
699	#endif
700
701	RTCritSectLeave(&pThis->CritSect);
702	return VINF_SUCCESS;
703	}
704
705	RTCritSectLeave(&pThis->CritSect);
706
707	/*
708	* Quit if the wait already timed out.
709	*/
710	if (rcWait == VERR_TIMEOUT)
711	{
712	rc = VERR_TIMEOUT;
713	break;
714	}
715	}
716
717	/*
718	* Timeout/error case, clean up.
719	*/
720	if (pThis->u32Magic == RTSEMRW_MAGIC)
721	{
722	RTCritSectEnter(&pThis->CritSect);
723	/* Adjust this counter, whether we got the critsect or not. */
724	pThis->cWritesWaiting--;
725	RTCritSectLeave(&pThis->CritSect);
726	}
727	return rc;
728	}
729
730
731	#undef RTSemRWRequestWrite
732	RTDECL(int) RTSemRWRequestWrite(RTSEMRW RWSem, unsigned cMillies)
733	{
734	#ifndef RTSEMRW_STRICT
735	return rtSemRWRequestWrite(RWSem, cMillies, false, NULL);
736	#else
737	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
738	return rtSemRWRequestWrite(RWSem, cMillies, false, &SrcPos);
739	#endif
740	}
741	RT_EXPORT_SYMBOL(RTSemRWRequestWrite);
742
743
744	RTDECL(int) RTSemRWRequestWriteDebug(RTSEMRW RWSem, unsigned cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
745	{
746	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
747	return rtSemRWRequestWrite(RWSem, cMillies, false, &SrcPos);
748	}
749	RT_EXPORT_SYMBOL(RTSemRWRequestWriteDebug);
750
751
752	#undef RTSemRWRequestWriteNoResume
753	RTDECL(int) RTSemRWRequestWriteNoResume(RTSEMRW RWSem, unsigned cMillies)
754	{
755	#ifndef RTSEMRW_STRICT
756	return rtSemRWRequestWrite(RWSem, cMillies, true, NULL);
757	#else
758	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
759	return rtSemRWRequestWrite(RWSem, cMillies, true, &SrcPos);
760	#endif
761	}
762	RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResume);
763
764
765	RTDECL(int) RTSemRWRequestWriteNoResumeDebug(RTSEMRW RWSem, unsigned cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
766	{
767	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
768	return rtSemRWRequestWrite(RWSem, cMillies, true, &SrcPos);
769	}
770	RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResumeDebug);
771
772
773	RTDECL(int) RTSemRWReleaseWrite(RTSEMRW RWSem)
774	{
775
776	/*
777	* Validate handle.
778	*/
779	struct RTSEMRWINTERNAL *pThis = RWSem;
780	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
781	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
782
783	/*
784	* Take critsect.
785	*/
786	int rc = RTCritSectEnter(&pThis->CritSect);
787	AssertRCReturn(rc, rc);
788
789	/*
790	* Check if owner.
791	*/
792	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
793	if (pThis->hWriter != hNativeSelf)
794	{
795	RTCritSectLeave(&pThis->CritSect);
796	AssertMsgFailed(("Not read-write owner of rwsem %p.\n", RWSem));
797	return VERR_NOT_OWNER;
798	}
799
800	#ifdef RTSEMRW_STRICT
801	if (pThis->cWrites > 1 \|\| !pThis->cWriterReads) /* don't check+release if VERR_WRONG_ORDER */
802	{
803	int rc9 = RTLockValidatorRecExclReleaseOwner(&pThis->ValidatorWrite, pThis->cWrites == 1);
804	if (RT_FAILURE(rc9))
805	{
806	RTCritSectLeave(&pThis->CritSect);
807	return rc9;
808	}
809	}
810	#endif
811
812	/*
813	* Release ownership and remove ourselves from the writers count.
814	*/
815	Assert(pThis->cWrites > 0);
816	pThis->cWrites--;
817	if (!pThis->cWrites)
818	{
819	if (RT_UNLIKELY(pThis->cWriterReads > 0))
820	{
821	pThis->cWrites++;
822	RTCritSectLeave(&pThis->CritSect);
823	AssertMsgFailed(("All recursive read locks need to be released prior to the final write lock! (%p)n\n", pThis));
824	return VERR_WRONG_ORDER;
825	}
826
827	pThis->hWriter = NIL_RTNATIVETHREAD;
828	}
829
830	/*
831	* Release the readers if no more writers waiting, otherwise the writers.
832	*/
833	if (!pThis->cWritesWaiting)
834	{
835	rc = RTSemEventMultiSignal(pThis->ReadEvent);
836	AssertMsgRC(rc, ("RTSemEventMultiSignal failed for rwsem %p, rc=%Rrc.\n", RWSem, rc));
837	pThis->fNeedResetReadEvent = true;
838	}
839	else
840	{
841	rc = RTSemEventSignal(pThis->WriteEvent);
842	AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", RWSem, rc));
843	}
844	RTCritSectLeave(&pThis->CritSect);
845
846	return rc;
847	}
848	RT_EXPORT_SYMBOL(RTSemRWReleaseWrite);
849
850
851	RTDECL(bool) RTSemRWIsWriteOwner(RTSEMRW RWSem)
852	{
853	struct RTSEMRWINTERNAL *pThis = RWSem;
854
855	/*
856	* Validate handle.
857	*/
858	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
859	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
860
861	/*
862	* Check ownership.
863	*/
864	RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
865	RTNATIVETHREAD hWriter;
866	ASMAtomicUoReadHandle(&pThis->hWriter, &hWriter);
867	return hWriter == hNativeSelf;
868	}
869	RT_EXPORT_SYMBOL(RTSemRWIsWriteOwner);
870
871
872	RTDECL(uint32_t) RTSemRWGetWriteRecursion(RTSEMRW RWSem)
873	{
874	struct RTSEMRWINTERNAL *pThis = RWSem;
875
876	/*
877	* Validate handle.
878	*/
879	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
880	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
881
882	/*
883	* Return the requested data.
884	*/
885	return pThis->cWrites;
886	}
887	RT_EXPORT_SYMBOL(RTSemRWGetWriteRecursion);
888
889
890	RTDECL(uint32_t) RTSemRWGetWriterReadRecursion(RTSEMRW RWSem)
891	{
892	struct RTSEMRWINTERNAL *pThis = RWSem;
893
894	/*
895	* Validate handle.
896	*/
897	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
898	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
899
900	/*
901	* Return the requested data.
902	*/
903	return pThis->cWriterReads;
904	}
905	RT_EXPORT_SYMBOL(RTSemRWGetWriterReadRecursion);
906
907
908	RTDECL(uint32_t) RTSemRWGetReadCount(RTSEMRW RWSem)
909	{
910	/*
911	* Validate input.
912	*/
913	struct RTSEMRWINTERNAL *pThis = RWSem;
914	AssertPtrReturn(pThis, 0);
915	AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC,
916	("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
917	0);
918
919	/*
920	* Return the requested data.
921	*/
922	return pThis->cReads;
923	}
924	RT_EXPORT_SYMBOL(RTSemRWGetReadCount);
925

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source: vbox/trunk/src/VBox/Runtime/generic/semrw-generic.cpp@ 25707

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