semrw-generic.cpp@ 100765

Last change on this file since 100765 was 98103, checked in by vboxsync, 2 years ago
Copyright year updates by scm.
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1	/* $Id: semrw-generic.cpp 98103 2023-01-17 14:15:46Z 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) 2006-2023 Oracle and/or its affiliates.
11	*
12	* This file is part of VirtualBox base platform packages, as
13	* available from https://www.virtualbox.org.
14	*
15	* This program is free software; you can redistribute it and/or
16	* modify it under the terms of the GNU General Public License
17	* as published by the Free Software Foundation, in version 3 of the
18	* License.
19	*
20	* This program is distributed in the hope that it will be useful, but
21	* WITHOUT ANY WARRANTY; without even the implied warranty of
22	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23	* General Public License for more details.
24	*
25	* You should have received a copy of the GNU General Public License
26	* along with this program; if not, see <https://www.gnu.org/licenses>.
27	*
28	* The contents of this file may alternatively be used under the terms
29	* of the Common Development and Distribution License Version 1.0
30	* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
31	* in the VirtualBox distribution, in which case the provisions of the
32	* CDDL are applicable instead of those of the GPL.
33	*
34	* You may elect to license modified versions of this file under the
35	* terms and conditions of either the GPL or the CDDL or both.
36	*
37	* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
38	*/
39
40
41	/*********************************************************************************************************************************
42	* Header Files *
43	*********************************************************************************************************************************/
44	#define RTSEMRW_WITHOUT_REMAPPING
45	#include <iprt/semaphore.h>
46	#include "internal/iprt.h"
47
48	#include <iprt/asm.h>
49	#include <iprt/assert.h>
50	#include <iprt/critsect.h>
51	#include <iprt/err.h>
52	#include <iprt/lockvalidator.h>
53	#include <iprt/mem.h>
54	#include <iprt/time.h>
55	#include <iprt/thread.h>
56
57	#include "internal/magics.h"
58	#include "internal/strict.h"
59
60
61	/*********************************************************************************************************************************
62	* Structures and Typedefs *
63	*********************************************************************************************************************************/
64
65	/** Internal representation of a Read-Write semaphore for the
66	* Generic implementation. */
67	struct RTSEMRWINTERNAL
68	{
69	/** The usual magic. (RTSEMRW_MAGIC) */
70	uint32_t u32Magic;
71	/* Alignment padding. */
72	uint32_t u32Padding;
73	/** This critical section serializes the access to and updating of the structure members. */
74	RTCRITSECT CritSect;
75	/** The current number of reads. (pure read recursion counts too) */
76	uint32_t cReads;
77	/** The current number of writes. (recursion counts too) */
78	uint32_t cWrites;
79	/** Number of read recursions by the writer. */
80	uint32_t cWriterReads;
81	/** Number of writers waiting. */
82	uint32_t cWritesWaiting;
83	/** The write owner of the lock. */
84	RTNATIVETHREAD hWriter;
85	/** The handle of the event object on which the waiting readers block. (manual reset). */
86	RTSEMEVENTMULTI ReadEvent;
87	/** The handle of the event object on which the waiting writers block. (automatic reset). */
88	RTSEMEVENT WriteEvent;
89	/** Need to reset ReadEvent. */
90	bool fNeedResetReadEvent;
91	#ifdef RTSEMRW_STRICT
92	/** The validator record for the writer. */
93	RTLOCKVALRECEXCL ValidatorWrite;
94	/** The validator record for the readers. */
95	RTLOCKVALRECSHRD ValidatorRead;
96	#endif
97	};
98
99
100
101	RTDECL(int) RTSemRWCreate(PRTSEMRW phRWSem)
102	{
103	return RTSemRWCreateEx(phRWSem, 0 /fFlags/, NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, "RTSemRW");
104	}
105	RT_EXPORT_SYMBOL(RTSemRWCreate);
106
107
108	RTDECL(int) RTSemRWCreateEx(PRTSEMRW phRWSem, uint32_t fFlags,
109	RTLOCKVALCLASS hClass, uint32_t uSubClass, const char *pszNameFmt, ...)
110	{
111	AssertReturn(!(fFlags & ~RTSEMRW_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
112
113	/*
114	* Allocate memory.
115	*/
116	int rc;
117	struct RTSEMRWINTERNAL pThis = (struct RTSEMRWINTERNAL )RTMemAlloc(sizeof(struct RTSEMRWINTERNAL));
118	if (pThis)
119	{
120	/*
121	* Create the semaphores.
122	*/
123	rc = RTSemEventCreateEx(&pThis->WriteEvent, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
124	if (RT_SUCCESS(rc))
125	{
126	rc = RTSemEventMultiCreateEx(&pThis->ReadEvent, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
127	if (RT_SUCCESS(rc))
128	{
129	rc = RTCritSectInitEx(&pThis->CritSect, RTCRITSECT_FLAGS_NO_LOCK_VAL,
130	NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, NULL);
131	if (RT_SUCCESS(rc))
132	{
133	/*
134	* Signal the read semaphore and initialize other variables.
135	*/
136	rc = RTSemEventMultiSignal(pThis->ReadEvent);
137	if (RT_SUCCESS(rc))
138	{
139	pThis->u32Padding = UINT32_C(0xa5a55a5a);
140	pThis->cReads = 0;
141	pThis->cWrites = 0;
142	pThis->cWriterReads = 0;
143	pThis->cWritesWaiting = 0;
144	pThis->hWriter = NIL_RTNATIVETHREAD;
145	pThis->fNeedResetReadEvent = true;
146	pThis->u32Magic = RTSEMRW_MAGIC;
147	#ifdef RTSEMRW_STRICT
148	bool const fLVEnabled = !(fFlags & RTSEMRW_FLAGS_NO_LOCK_VAL);
149	if (!pszNameFmt)
150	{
151	static uint32_t volatile s_iSemRWAnon = 0;
152	uint32_t i = ASMAtomicIncU32(&s_iSemRWAnon) - 1;
153	RTLockValidatorRecExclInit(&pThis->ValidatorWrite, hClass, uSubClass, pThis,
154	fLVEnabled, "RTSemRW-%u", i);
155	RTLockValidatorRecSharedInit(&pThis->ValidatorRead, hClass, uSubClass, pThis,
156	false /fSignaller/, fLVEnabled, "RTSemRW-%u", i);
157	}
158	else
159	{
160	va_list va;
161	va_start(va, pszNameFmt);
162	RTLockValidatorRecExclInitV(&pThis->ValidatorWrite, hClass, uSubClass, pThis,
163	fLVEnabled, pszNameFmt, va);
164	va_end(va);
165	va_start(va, pszNameFmt);
166	RTLockValidatorRecSharedInitV(&pThis->ValidatorRead, hClass, uSubClass, pThis,
167	false /fSignaller/, fLVEnabled, pszNameFmt, va);
168	va_end(va);
169	}
170	RTLockValidatorRecMakeSiblings(&pThis->ValidatorWrite.Core, &pThis->ValidatorRead.Core);
171	#else
172	RT_NOREF_PV(hClass); RT_NOREF_PV(uSubClass); RT_NOREF_PV(pszNameFmt);
173	#endif
174	*phRWSem = pThis;
175	return VINF_SUCCESS;
176	}
177	RTCritSectDelete(&pThis->CritSect);
178	}
179	RTSemEventMultiDestroy(pThis->ReadEvent);
180	}
181	RTSemEventDestroy(pThis->WriteEvent);
182	}
183	RTMemFree(pThis);
184	}
185	else
186	rc = VERR_NO_MEMORY;
187
188	return rc;
189	}
190	RT_EXPORT_SYMBOL(RTSemRWCreate);
191
192
193	RTDECL(int) RTSemRWDestroy(RTSEMRW hRWSem)
194	{
195	struct RTSEMRWINTERNAL *pThis = hRWSem;
196
197	/*
198	* Validate handle.
199	*/
200	if (pThis == NIL_RTSEMRW)
201	return VINF_SUCCESS;
202	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
203	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
204
205	/*
206	* Check if busy.
207	*/
208	int rc = RTCritSectTryEnter(&pThis->CritSect);
209	if (RT_SUCCESS(rc))
210	{
211	if (!pThis->cReads && !pThis->cWrites)
212	{
213	/*
214	* Make it invalid and unusable.
215	*/
216	ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMRW_MAGIC);
217	pThis->cReads = UINT32_MAX;
218
219	/*
220	* Do actual cleanup. None of these can now fail.
221	*/
222	rc = RTSemEventMultiDestroy(pThis->ReadEvent);
223	AssertMsgRC(rc, ("RTSemEventMultiDestroy failed! rc=%Rrc\n", rc));
224	pThis->ReadEvent = NIL_RTSEMEVENTMULTI;
225
226	rc = RTSemEventDestroy(pThis->WriteEvent);
227	AssertMsgRC(rc, ("RTSemEventDestroy failed! rc=%Rrc\n", rc));
228	pThis->WriteEvent = NIL_RTSEMEVENT;
229
230	RTCritSectLeave(&pThis->CritSect);
231	rc = RTCritSectDelete(&pThis->CritSect);
232	AssertMsgRC(rc, ("RTCritSectDelete failed! rc=%Rrc\n", rc));
233
234	#ifdef RTSEMRW_STRICT
235	RTLockValidatorRecSharedDelete(&pThis->ValidatorRead);
236	RTLockValidatorRecExclDelete(&pThis->ValidatorWrite);
237	#endif
238	RTMemFree(pThis);
239	rc = VINF_SUCCESS;
240	}
241	else
242	{
243	rc = VERR_SEM_BUSY;
244	RTCritSectLeave(&pThis->CritSect);
245	}
246	}
247	else
248	{
249	AssertMsgRC(rc, ("RTCritSectTryEnter failed! rc=%Rrc\n", rc));
250	rc = VERR_SEM_BUSY;
251	}
252
253	return rc;
254	}
255	RT_EXPORT_SYMBOL(RTSemRWDestroy);
256
257
258	RTDECL(uint32_t) RTSemRWSetSubClass(RTSEMRW hRWSem, uint32_t uSubClass)
259	{
260	#ifdef RTSEMRW_STRICT
261	/*
262	* Validate handle.
263	*/
264	struct RTSEMRWINTERNAL *pThis = hRWSem;
265	AssertPtrReturn(pThis, RTLOCKVAL_SUB_CLASS_INVALID);
266	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, RTLOCKVAL_SUB_CLASS_INVALID);
267
268	RTLockValidatorRecSharedSetSubClass(&pThis->ValidatorRead, uSubClass);
269	return RTLockValidatorRecExclSetSubClass(&pThis->ValidatorWrite, uSubClass);
270	#else
271	RT_NOREF_PV(hRWSem); RT_NOREF_PV(uSubClass);
272	return RTLOCKVAL_SUB_CLASS_INVALID;
273	#endif
274	}
275	RT_EXPORT_SYMBOL(RTSemRWSetSubClass);
276
277
278	DECL_FORCE_INLINE(int) rtSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
279	{
280	/*
281	* Validate handle.
282	*/
283	struct RTSEMRWINTERNAL *pThis = hRWSem;
284	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
285	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
286
287	RTMSINTERVAL cMilliesInitial = cMillies;
288	uint64_t tsStart = 0;
289	if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
290	tsStart = RTTimeNanoTS();
291
292	#ifdef RTSEMRW_STRICT
293	RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt();
294	if (cMillies > 0)
295	{
296	int rc9;
297	if (pThis->hWriter != NIL_RTTHREAD && pThis->hWriter == RTThreadNativeSelf())
298	rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
299	else
300	rc9 = RTLockValidatorRecSharedCheckOrder(&pThis->ValidatorRead, hThreadSelf, pSrcPos, cMillies);
301	if (RT_FAILURE(rc9))
302	return rc9;
303	}
304	#endif
305
306	/*
307	* Take critsect.
308	*/
309	int rc = RTCritSectEnter(&pThis->CritSect);
310	if (RT_FAILURE(rc))
311	{
312	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
313	return rc;
314	}
315
316	/*
317	* Check if the state of affairs allows read access.
318	* Do not block further readers if there is a writer waiting, as
319	* that will break/deadlock reader recursion.
320	*/
321	if ( pThis->hWriter == NIL_RTNATIVETHREAD
322	#if 0
323	&& ( !pThis->cWritesWaiting
324	\|\| pThis->cReads)
325	#endif
326	)
327	{
328	pThis->cReads++;
329	Assert(pThis->cReads > 0);
330	#ifdef RTSEMRW_STRICT
331	RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
332	#endif
333
334	RTCritSectLeave(&pThis->CritSect);
335	return VINF_SUCCESS;
336	}
337
338	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
339	if (pThis->hWriter == hNativeSelf)
340	{
341	#ifdef RTSEMRW_STRICT
342	int rc9 = RTLockValidatorRecExclRecursionMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core, pSrcPos);
343	if (RT_FAILURE(rc9))
344	{
345	RTCritSectLeave(&pThis->CritSect);
346	return rc9;
347	}
348	#endif
349
350	pThis->cWriterReads++;
351	Assert(pThis->cWriterReads > 0);
352
353	RTCritSectLeave(&pThis->CritSect);
354	return VINF_SUCCESS;
355	}
356
357	RTCritSectLeave(&pThis->CritSect);
358
359	/*
360	* Wait till it's ready for reading.
361	*/
362	if (cMillies == 0)
363	return VERR_TIMEOUT;
364
365	#ifndef RTSEMRW_STRICT
366	RTTHREAD hThreadSelf = RTThreadSelf();
367	#endif
368	for (;;)
369	{
370	if (cMillies != RT_INDEFINITE_WAIT)
371	{
372	int64_t tsDelta = RTTimeNanoTS() - tsStart;
373	if (tsDelta >= 1000000)
374	{
375	tsDelta /= 1000000;
376	if ((uint64_t)tsDelta < cMilliesInitial)
377	cMilliesInitial = (RTMSINTERVAL)tsDelta;
378	else
379	cMilliesInitial = 1;
380	}
381	}
382	#ifdef RTSEMRW_STRICT
383	rc = RTLockValidatorRecSharedCheckBlocking(&pThis->ValidatorRead, hThreadSelf, pSrcPos, true,
384	cMillies, RTTHREADSTATE_RW_READ, false);
385	if (RT_FAILURE(rc))
386	break;
387	#else
388	RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_READ, false);
389	RT_NOREF_PV(pSrcPos);
390	#endif
391	int rcWait;
392	if (fInterruptible)
393	rcWait = rc = RTSemEventMultiWaitNoResume(pThis->ReadEvent, cMillies);
394	else
395	rcWait = rc = RTSemEventMultiWait(pThis->ReadEvent, cMillies);
396	RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_READ);
397	if (RT_FAILURE(rc) && rc != VERR_TIMEOUT) /* handle timeout below */
398	{
399	AssertMsgRC(rc, ("RTSemEventMultiWait failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
400	break;
401	}
402
403	if (pThis->u32Magic != RTSEMRW_MAGIC)
404	{
405	rc = VERR_SEM_DESTROYED;
406	break;
407	}
408
409	/*
410	* Re-take critsect and repeat the check we did before the loop.
411	*/
412	rc = RTCritSectEnter(&pThis->CritSect);
413	if (RT_FAILURE(rc))
414	{
415	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
416	break;
417	}
418
419	if ( pThis->hWriter == NIL_RTNATIVETHREAD
420	#if 0
421	&& ( !pThis->cWritesWaiting
422	\|\| pThis->cReads)
423	#endif
424	)
425	{
426	pThis->cReads++;
427	Assert(pThis->cReads > 0);
428	#ifdef RTSEMRW_STRICT
429	RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
430	#endif
431
432	RTCritSectLeave(&pThis->CritSect);
433	return VINF_SUCCESS;
434	}
435
436	RTCritSectLeave(&pThis->CritSect);
437
438	/*
439	* Quit if the wait already timed out.
440	*/
441	if (rcWait == VERR_TIMEOUT)
442	{
443	rc = VERR_TIMEOUT;
444	break;
445	}
446	}
447
448	/* failed */
449	return rc;
450	}
451
452
453	RTDECL(int) RTSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
454	{
455	#ifndef RTSEMRW_STRICT
456	return rtSemRWRequestRead(hRWSem, cMillies, false, NULL);
457	#else
458	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
459	return rtSemRWRequestRead(hRWSem, cMillies, false, &SrcPos);
460	#endif
461	}
462	RT_EXPORT_SYMBOL(RTSemRWRequestRead);
463
464
465	RTDECL(int) RTSemRWRequestReadDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
466	{
467	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
468	return rtSemRWRequestRead(hRWSem, cMillies, false, &SrcPos);
469	}
470	RT_EXPORT_SYMBOL(RTSemRWRequestReadDebug);
471
472
473	RTDECL(int) RTSemRWRequestReadNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
474	{
475	#ifndef RTSEMRW_STRICT
476	return rtSemRWRequestRead(hRWSem, cMillies, true, NULL);
477	#else
478	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
479	return rtSemRWRequestRead(hRWSem, cMillies, true, &SrcPos);
480	#endif
481	}
482	RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResume);
483
484
485	RTDECL(int) RTSemRWRequestReadNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
486	{
487	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
488	return rtSemRWRequestRead(hRWSem, cMillies, true, &SrcPos);
489	}
490	RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResumeDebug);
491
492
493	RTDECL(int) RTSemRWReleaseRead(RTSEMRW hRWSem)
494	{
495	struct RTSEMRWINTERNAL *pThis = hRWSem;
496
497	/*
498	* Validate handle.
499	*/
500	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
501	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
502
503	/*
504	* Take critsect.
505	*/
506	int rc = RTCritSectEnter(&pThis->CritSect);
507	if (RT_SUCCESS(rc))
508	{
509	if (pThis->hWriter == NIL_RTNATIVETHREAD)
510	{
511	#ifdef RTSEMRW_STRICT
512	rc = RTLockValidatorRecSharedCheckAndRelease(&pThis->ValidatorRead, NIL_RTTHREAD);
513	if (RT_SUCCESS(rc))
514	#endif
515	{
516	if (RT_LIKELY(pThis->cReads > 0))
517	{
518	pThis->cReads--;
519
520	/* Kick off a writer if appropriate. */
521	if ( pThis->cWritesWaiting > 0
522	&& !pThis->cReads)
523	{
524	rc = RTSemEventSignal(pThis->WriteEvent);
525	AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", hRWSem, rc));
526	}
527	}
528	else
529	{
530	AssertFailed();
531	rc = VERR_NOT_OWNER;
532	}
533	}
534	}
535	else
536	{
537	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
538	if (pThis->hWriter == hNativeSelf)
539	{
540	if (pThis->cWriterReads > 0)
541	{
542	#ifdef RTSEMRW_STRICT
543	rc = RTLockValidatorRecExclUnwindMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core);
544	if (RT_SUCCESS(rc))
545	#endif
546	{
547	pThis->cWriterReads--;
548	}
549	}
550	else
551	{
552	AssertFailed();
553	rc = VERR_NOT_OWNER;
554	}
555	}
556	else
557	{
558	AssertFailed();
559	rc = VERR_NOT_OWNER;
560	}
561	}
562
563	RTCritSectLeave(&pThis->CritSect);
564	}
565	else
566	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
567
568	return rc;
569	}
570	RT_EXPORT_SYMBOL(RTSemRWReleaseRead);
571
572
573	DECL_FORCE_INLINE(int) rtSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
574	{
575	/*
576	* Validate handle.
577	*/
578	struct RTSEMRWINTERNAL *pThis = hRWSem;
579	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
580	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
581
582	RTMSINTERVAL cMilliesInitial = cMillies;
583	uint64_t tsStart = 0;
584	if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
585	tsStart = RTTimeNanoTS();
586
587	#ifdef RTSEMRW_STRICT
588	RTTHREAD hThreadSelf = NIL_RTTHREAD;
589	if (cMillies)
590	{
591	hThreadSelf = RTThreadSelfAutoAdopt();
592	int rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
593	if (RT_FAILURE(rc9))
594	return rc9;
595	}
596	#endif
597
598	/*
599	* Take critsect.
600	*/
601	int rc = RTCritSectEnter(&pThis->CritSect);
602	if (RT_FAILURE(rc))
603	{
604	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
605	return rc;
606	}
607
608	/*
609	* Check if the state of affairs allows write access.
610	*/
611	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
612	if ( !pThis->cReads
613	&& ( ( !pThis->cWrites
614	&& ( !pThis->cWritesWaiting /* play fair if we can wait */
615	\|\| !cMillies)
616	)
617	\|\| pThis->hWriter == hNativeSelf
618	)
619	)
620	{
621	/*
622	* Reset the reader event semaphore if necessary.
623	*/
624	if (pThis->fNeedResetReadEvent)
625	{
626	pThis->fNeedResetReadEvent = false;
627	rc = RTSemEventMultiReset(pThis->ReadEvent);
628	AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", hRWSem, rc));
629	}
630
631	pThis->cWrites++;
632	pThis->hWriter = hNativeSelf;
633	#ifdef RTSEMRW_STRICT
634	RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, pThis->cWrites == 1);
635	#endif
636	RTCritSectLeave(&pThis->CritSect);
637	return VINF_SUCCESS;
638	}
639
640	/*
641	* Signal writer presence.
642	*/
643	if (cMillies != 0)
644	pThis->cWritesWaiting++;
645
646	RTCritSectLeave(&pThis->CritSect);
647
648	/*
649	* Wait till it's ready for writing.
650	*/
651	if (cMillies == 0)
652	return VERR_TIMEOUT;
653
654	#ifndef RTSEMRW_STRICT
655	RTTHREAD hThreadSelf = RTThreadSelf();
656	#endif
657	for (;;)
658	{
659	if (cMillies != RT_INDEFINITE_WAIT)
660	{
661	int64_t tsDelta = RTTimeNanoTS() - tsStart;
662	if (tsDelta >= 1000000)
663	{
664	tsDelta /= 1000000;
665	if ((uint64_t)tsDelta < cMilliesInitial)
666	cMilliesInitial = (RTMSINTERVAL)tsDelta;
667	else
668	cMilliesInitial = 1;
669	}
670	}
671
672	#ifdef RTSEMRW_STRICT
673	rc = RTLockValidatorRecExclCheckBlocking(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true,
674	cMillies, RTTHREADSTATE_RW_WRITE, false);
675	if (RT_FAILURE(rc))
676	break;
677	#else
678	RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_WRITE, false);
679	RT_NOREF_PV(pSrcPos);
680	#endif
681	int rcWait;
682	if (fInterruptible)
683	rcWait = rc = RTSemEventWaitNoResume(pThis->WriteEvent, cMillies);
684	else
685	rcWait = rc = RTSemEventWait(pThis->WriteEvent, cMillies);
686	RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_WRITE);
687	if (RT_UNLIKELY(RT_FAILURE_NP(rc) && rc != VERR_TIMEOUT)) /* timeouts are handled below */
688	{
689	AssertMsgRC(rc, ("RTSemEventWait failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
690	break;
691	}
692
693	if (RT_UNLIKELY(pThis->u32Magic != RTSEMRW_MAGIC))
694	{
695	rc = VERR_SEM_DESTROYED;
696	break;
697	}
698
699	/*
700	* Re-take critsect and repeat the check we did prior to this loop.
701	*/
702	rc = RTCritSectEnter(&pThis->CritSect);
703	if (RT_FAILURE(rc))
704	{
705	AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
706	break;
707	}
708
709	if (!pThis->cReads && (!pThis->cWrites \|\| pThis->hWriter == hNativeSelf))
710	{
711	/*
712	* Reset the reader event semaphore if necessary.
713	*/
714	if (pThis->fNeedResetReadEvent)
715	{
716	pThis->fNeedResetReadEvent = false;
717	rc = RTSemEventMultiReset(pThis->ReadEvent);
718	AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", hRWSem, rc));
719	}
720
721	pThis->cWrites++;
722	pThis->hWriter = hNativeSelf;
723	pThis->cWritesWaiting--;
724	#ifdef RTSEMRW_STRICT
725	RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true);
726	#endif
727
728	RTCritSectLeave(&pThis->CritSect);
729	return VINF_SUCCESS;
730	}
731
732	RTCritSectLeave(&pThis->CritSect);
733
734	/*
735	* Quit if the wait already timed out.
736	*/
737	if (rcWait == VERR_TIMEOUT)
738	{
739	rc = VERR_TIMEOUT;
740	break;
741	}
742	}
743
744	/*
745	* Timeout/error case, clean up.
746	*/
747	if (pThis->u32Magic == RTSEMRW_MAGIC)
748	{
749	RTCritSectEnter(&pThis->CritSect);
750	/* Adjust this counter, whether we got the critsect or not. */
751	pThis->cWritesWaiting--;
752	RTCritSectLeave(&pThis->CritSect);
753	}
754	return rc;
755	}
756
757
758	RTDECL(int) RTSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
759	{
760	#ifndef RTSEMRW_STRICT
761	return rtSemRWRequestWrite(hRWSem, cMillies, false, NULL);
762	#else
763	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
764	return rtSemRWRequestWrite(hRWSem, cMillies, false, &SrcPos);
765	#endif
766	}
767	RT_EXPORT_SYMBOL(RTSemRWRequestWrite);
768
769
770	RTDECL(int) RTSemRWRequestWriteDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
771	{
772	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
773	return rtSemRWRequestWrite(hRWSem, cMillies, false, &SrcPos);
774	}
775	RT_EXPORT_SYMBOL(RTSemRWRequestWriteDebug);
776
777
778	RTDECL(int) RTSemRWRequestWriteNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
779	{
780	#ifndef RTSEMRW_STRICT
781	return rtSemRWRequestWrite(hRWSem, cMillies, true, NULL);
782	#else
783	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
784	return rtSemRWRequestWrite(hRWSem, cMillies, true, &SrcPos);
785	#endif
786	}
787	RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResume);
788
789
790	RTDECL(int) RTSemRWRequestWriteNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
791	{
792	RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
793	return rtSemRWRequestWrite(hRWSem, cMillies, true, &SrcPos);
794	}
795	RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResumeDebug);
796
797
798	RTDECL(int) RTSemRWReleaseWrite(RTSEMRW hRWSem)
799	{
800
801	/*
802	* Validate handle.
803	*/
804	struct RTSEMRWINTERNAL *pThis = hRWSem;
805	AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
806	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
807
808	/*
809	* Take critsect.
810	*/
811	int rc = RTCritSectEnter(&pThis->CritSect);
812	AssertRCReturn(rc, rc);
813
814	/*
815	* Check if owner.
816	*/
817	RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
818	if (pThis->hWriter != hNativeSelf)
819	{
820	RTCritSectLeave(&pThis->CritSect);
821	AssertMsgFailed(("Not read-write owner of rwsem %p.\n", hRWSem));
822	return VERR_NOT_OWNER;
823	}
824
825	#ifdef RTSEMRW_STRICT
826	if (pThis->cWrites > 1 \|\| !pThis->cWriterReads) /* don't check+release if VERR_WRONG_ORDER */
827	{
828	int rc9 = RTLockValidatorRecExclReleaseOwner(&pThis->ValidatorWrite, pThis->cWrites == 1);
829	if (RT_FAILURE(rc9))
830	{
831	RTCritSectLeave(&pThis->CritSect);
832	return rc9;
833	}
834	}
835	#endif
836
837	/*
838	* Release ownership and remove ourselves from the writers count.
839	*/
840	Assert(pThis->cWrites > 0);
841	pThis->cWrites--;
842	if (!pThis->cWrites)
843	{
844	if (RT_UNLIKELY(pThis->cWriterReads > 0))
845	{
846	pThis->cWrites++;
847	RTCritSectLeave(&pThis->CritSect);
848	AssertMsgFailed(("All recursive read locks need to be released prior to the final write lock! (%p)n\n", pThis));
849	return VERR_WRONG_ORDER;
850	}
851
852	pThis->hWriter = NIL_RTNATIVETHREAD;
853	}
854
855	/*
856	* Release the readers if no more writers waiting, otherwise the writers.
857	*/
858	if (!pThis->cWritesWaiting)
859	{
860	rc = RTSemEventMultiSignal(pThis->ReadEvent);
861	AssertMsgRC(rc, ("RTSemEventMultiSignal failed for rwsem %p, rc=%Rrc.\n", hRWSem, rc));
862	pThis->fNeedResetReadEvent = true;
863	}
864	else
865	{
866	rc = RTSemEventSignal(pThis->WriteEvent);
867	AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", hRWSem, rc));
868	}
869	RTCritSectLeave(&pThis->CritSect);
870
871	return rc;
872	}
873	RT_EXPORT_SYMBOL(RTSemRWReleaseWrite);
874
875
876	RTDECL(bool) RTSemRWIsWriteOwner(RTSEMRW hRWSem)
877	{
878	/*
879	* Validate handle.
880	*/
881	struct RTSEMRWINTERNAL *pThis = hRWSem;
882	AssertPtrReturn(pThis, false);
883	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, false);
884
885	/*
886	* Check ownership.
887	*/
888	RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
889	RTNATIVETHREAD hWriter;
890	ASMAtomicUoReadHandle(&pThis->hWriter, &hWriter);
891	return hWriter == hNativeSelf;
892	}
893	RT_EXPORT_SYMBOL(RTSemRWIsWriteOwner);
894
895
896	RTDECL(bool) RTSemRWIsReadOwner(RTSEMRW hRWSem, bool fWannaHear)
897	{
898	/*
899	* Validate handle.
900	*/
901	struct RTSEMRWINTERNAL *pThis = hRWSem;
902	AssertPtrReturn(pThis, false);
903	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, false);
904
905	/*
906	* Check write ownership. The writer is also a valid reader.
907	*/
908	RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
909	RTNATIVETHREAD hWriter;
910	ASMAtomicUoReadHandle(&pThis->hWriter, &hWriter);
911	if (hWriter == hNativeSelf)
912	return true;
913	if (hWriter != NIL_RTNATIVETHREAD)
914	return false;
915
916	#ifdef RTSEMRW_STRICT
917	/*
918	* Ask the lock validator.
919	*/
920	NOREF(fWannaHear);
921	return RTLockValidatorRecSharedIsOwner(&pThis->ValidatorRead, NIL_RTTHREAD);
922	#else
923	/*
924	* If there are no reads we cannot be one of them... But if there are we
925	* cannot know and can only return what the caller want to hear.
926	*/
927	if (pThis->cReads == 0)
928	return false;
929	return fWannaHear;
930	#endif
931	}
932	RT_EXPORT_SYMBOL(RTSemRWIsReadOwner);
933
934
935	RTDECL(uint32_t) RTSemRWGetWriteRecursion(RTSEMRW hRWSem)
936	{
937	struct RTSEMRWINTERNAL *pThis = hRWSem;
938
939	/*
940	* Validate handle.
941	*/
942	AssertPtrReturn(pThis, 0);
943	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, 0);
944
945	/*
946	* Return the requested data.
947	*/
948	return pThis->cWrites;
949	}
950	RT_EXPORT_SYMBOL(RTSemRWGetWriteRecursion);
951
952
953	RTDECL(uint32_t) RTSemRWGetWriterReadRecursion(RTSEMRW hRWSem)
954	{
955	struct RTSEMRWINTERNAL *pThis = hRWSem;
956
957	/*
958	* Validate handle.
959	*/
960	AssertPtrReturn(pThis, 0);
961	AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, 0);
962
963	/*
964	* Return the requested data.
965	*/
966	return pThis->cWriterReads;
967	}
968	RT_EXPORT_SYMBOL(RTSemRWGetWriterReadRecursion);
969
970
971	RTDECL(uint32_t) RTSemRWGetReadCount(RTSEMRW hRWSem)
972	{
973	/*
974	* Validate input.
975	*/
976	struct RTSEMRWINTERNAL *pThis = hRWSem;
977	AssertPtrReturn(pThis, 0);
978	AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC,
979	("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
980	0);
981
982	/*
983	* Return the requested data.
984	*/
985	return pThis->cReads;
986	}
987	RT_EXPORT_SYMBOL(RTSemRWGetReadCount);
988

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source: vbox/trunk/src/VBox/Runtime/generic/semrw-generic.cpp@ 100765

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