VirtualBox

source: vbox/trunk/src/VBox/Runtime/generic/semrw-generic.cpp@ 76553

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1/* $Id: semrw-generic.cpp 76553 2019-01-01 01:45:53Z 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) 2006-2019 Oracle Corporation
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
30
31/*********************************************************************************************************************************
32* Header Files *
33*********************************************************************************************************************************/
34#define RTSEMRW_WITHOUT_REMAPPING
35#include <iprt/semaphore.h>
36#include "internal/iprt.h"
37
38#include <iprt/asm.h>
39#include <iprt/assert.h>
40#include <iprt/critsect.h>
41#include <iprt/err.h>
42#include <iprt/lockvalidator.h>
43#include <iprt/mem.h>
44#include <iprt/time.h>
45#include <iprt/thread.h>
46
47#include "internal/magics.h"
48#include "internal/strict.h"
49
50
51/*********************************************************************************************************************************
52* Structures and Typedefs *
53*********************************************************************************************************************************/
54
55/** Internal representation of a Read-Write semaphore for the
56 * Generic implementation. */
57struct RTSEMRWINTERNAL
58{
59 /** The usual magic. (RTSEMRW_MAGIC) */
60 uint32_t u32Magic;
61 /* Alignment padding. */
62 uint32_t u32Padding;
63 /** This critical section serializes the access to and updating of the structure members. */
64 RTCRITSECT CritSect;
65 /** The current number of reads. (pure read recursion counts too) */
66 uint32_t cReads;
67 /** The current number of writes. (recursion counts too) */
68 uint32_t cWrites;
69 /** Number of read recursions by the writer. */
70 uint32_t cWriterReads;
71 /** Number of writers waiting. */
72 uint32_t cWritesWaiting;
73 /** The write owner of the lock. */
74 RTNATIVETHREAD hWriter;
75 /** The handle of the event object on which the waiting readers block. (manual reset). */
76 RTSEMEVENTMULTI ReadEvent;
77 /** The handle of the event object on which the waiting writers block. (automatic reset). */
78 RTSEMEVENT WriteEvent;
79 /** Need to reset ReadEvent. */
80 bool fNeedResetReadEvent;
81#ifdef RTSEMRW_STRICT
82 /** The validator record for the writer. */
83 RTLOCKVALRECEXCL ValidatorWrite;
84 /** The validator record for the readers. */
85 RTLOCKVALRECSHRD ValidatorRead;
86#endif
87};
88
89
90
91RTDECL(int) RTSemRWCreate(PRTSEMRW phRWSem)
92{
93 return RTSemRWCreateEx(phRWSem, 0 /*fFlags*/, NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, "RTSemRW");
94}
95RT_EXPORT_SYMBOL(RTSemRWCreate);
96
97
98RTDECL(int) RTSemRWCreateEx(PRTSEMRW phRWSem, uint32_t fFlags,
99 RTLOCKVALCLASS hClass, uint32_t uSubClass, const char *pszNameFmt, ...)
100{
101 AssertReturn(!(fFlags & ~RTSEMRW_FLAGS_NO_LOCK_VAL), VERR_INVALID_PARAMETER);
102
103 /*
104 * Allocate memory.
105 */
106 int rc;
107 struct RTSEMRWINTERNAL *pThis = (struct RTSEMRWINTERNAL *)RTMemAlloc(sizeof(struct RTSEMRWINTERNAL));
108 if (pThis)
109 {
110 /*
111 * Create the semaphores.
112 */
113 rc = RTSemEventCreateEx(&pThis->WriteEvent, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
114 if (RT_SUCCESS(rc))
115 {
116 rc = RTSemEventMultiCreateEx(&pThis->ReadEvent, RTSEMEVENT_FLAGS_NO_LOCK_VAL, NIL_RTLOCKVALCLASS, NULL);
117 if (RT_SUCCESS(rc))
118 {
119 rc = RTCritSectInitEx(&pThis->CritSect, RTCRITSECT_FLAGS_NO_LOCK_VAL,
120 NIL_RTLOCKVALCLASS, RTLOCKVAL_SUB_CLASS_NONE, NULL);
121 if (RT_SUCCESS(rc))
122 {
123 /*
124 * Signal the read semaphore and initialize other variables.
125 */
126 rc = RTSemEventMultiSignal(pThis->ReadEvent);
127 if (RT_SUCCESS(rc))
128 {
129 pThis->u32Padding = UINT32_C(0xa5a55a5a);
130 pThis->cReads = 0;
131 pThis->cWrites = 0;
132 pThis->cWriterReads = 0;
133 pThis->cWritesWaiting = 0;
134 pThis->hWriter = NIL_RTNATIVETHREAD;
135 pThis->fNeedResetReadEvent = true;
136 pThis->u32Magic = RTSEMRW_MAGIC;
137#ifdef RTSEMRW_STRICT
138 bool const fLVEnabled = !(fFlags & RTSEMRW_FLAGS_NO_LOCK_VAL);
139 if (!pszNameFmt)
140 {
141 static uint32_t volatile s_iSemRWAnon = 0;
142 uint32_t i = ASMAtomicIncU32(&s_iSemRWAnon) - 1;
143 RTLockValidatorRecExclInit(&pThis->ValidatorWrite, hClass, uSubClass, pThis,
144 fLVEnabled, "RTSemRW-%u", i);
145 RTLockValidatorRecSharedInit(&pThis->ValidatorRead, hClass, uSubClass, pThis,
146 false /*fSignaller*/, fLVEnabled, "RTSemRW-%u", i);
147 }
148 else
149 {
150 va_list va;
151 va_start(va, pszNameFmt);
152 RTLockValidatorRecExclInitV(&pThis->ValidatorWrite, hClass, uSubClass, pThis,
153 fLVEnabled, pszNameFmt, va);
154 va_end(va);
155 va_start(va, pszNameFmt);
156 RTLockValidatorRecSharedInitV(&pThis->ValidatorRead, hClass, uSubClass, pThis,
157 false /*fSignaller*/, fLVEnabled, pszNameFmt, va);
158 va_end(va);
159 }
160 RTLockValidatorRecMakeSiblings(&pThis->ValidatorWrite.Core, &pThis->ValidatorRead.Core);
161#else
162 RT_NOREF_PV(hClass); RT_NOREF_PV(uSubClass); RT_NOREF_PV(pszNameFmt);
163#endif
164 *phRWSem = pThis;
165 return VINF_SUCCESS;
166 }
167 RTCritSectDelete(&pThis->CritSect);
168 }
169 RTSemEventMultiDestroy(pThis->ReadEvent);
170 }
171 RTSemEventDestroy(pThis->WriteEvent);
172 }
173 RTMemFree(pThis);
174 }
175 else
176 rc = VERR_NO_MEMORY;
177
178 return rc;
179}
180RT_EXPORT_SYMBOL(RTSemRWCreate);
181
182
183RTDECL(int) RTSemRWDestroy(RTSEMRW hRWSem)
184{
185 struct RTSEMRWINTERNAL *pThis = hRWSem;
186
187 /*
188 * Validate handle.
189 */
190 if (pThis == NIL_RTSEMRW)
191 return VINF_SUCCESS;
192 AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
193 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
194
195 /*
196 * Check if busy.
197 */
198 int rc = RTCritSectTryEnter(&pThis->CritSect);
199 if (RT_SUCCESS(rc))
200 {
201 if (!pThis->cReads && !pThis->cWrites)
202 {
203 /*
204 * Make it invalid and unusable.
205 */
206 ASMAtomicWriteU32(&pThis->u32Magic, ~RTSEMRW_MAGIC);
207 pThis->cReads = UINT32_MAX;
208
209 /*
210 * Do actual cleanup. None of these can now fail.
211 */
212 rc = RTSemEventMultiDestroy(pThis->ReadEvent);
213 AssertMsgRC(rc, ("RTSemEventMultiDestroy failed! rc=%Rrc\n", rc));
214 pThis->ReadEvent = NIL_RTSEMEVENTMULTI;
215
216 rc = RTSemEventDestroy(pThis->WriteEvent);
217 AssertMsgRC(rc, ("RTSemEventDestroy failed! rc=%Rrc\n", rc));
218 pThis->WriteEvent = NIL_RTSEMEVENT;
219
220 RTCritSectLeave(&pThis->CritSect);
221 rc = RTCritSectDelete(&pThis->CritSect);
222 AssertMsgRC(rc, ("RTCritSectDelete failed! rc=%Rrc\n", rc));
223
224#ifdef RTSEMRW_STRICT
225 RTLockValidatorRecSharedDelete(&pThis->ValidatorRead);
226 RTLockValidatorRecExclDelete(&pThis->ValidatorWrite);
227#endif
228 RTMemFree(pThis);
229 rc = VINF_SUCCESS;
230 }
231 else
232 {
233 rc = VERR_SEM_BUSY;
234 RTCritSectLeave(&pThis->CritSect);
235 }
236 }
237 else
238 {
239 AssertMsgRC(rc, ("RTCritSectTryEnter failed! rc=%Rrc\n", rc));
240 rc = VERR_SEM_BUSY;
241 }
242
243 return rc;
244}
245RT_EXPORT_SYMBOL(RTSemRWDestroy);
246
247
248RTDECL(uint32_t) RTSemRWSetSubClass(RTSEMRW hRWSem, uint32_t uSubClass)
249{
250#ifdef RTSEMRW_STRICT
251 /*
252 * Validate handle.
253 */
254 struct RTSEMRWINTERNAL *pThis = hRWSem;
255 AssertPtrReturn(pThis, RTLOCKVAL_SUB_CLASS_INVALID);
256 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, RTLOCKVAL_SUB_CLASS_INVALID);
257
258 RTLockValidatorRecSharedSetSubClass(&pThis->ValidatorRead, uSubClass);
259 return RTLockValidatorRecExclSetSubClass(&pThis->ValidatorWrite, uSubClass);
260#else
261 RT_NOREF_PV(hRWSem); RT_NOREF_PV(uSubClass);
262 return RTLOCKVAL_SUB_CLASS_INVALID;
263#endif
264}
265RT_EXPORT_SYMBOL(RTSemRWSetSubClass);
266
267
268DECL_FORCE_INLINE(int) rtSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
269{
270 /*
271 * Validate handle.
272 */
273 struct RTSEMRWINTERNAL *pThis = hRWSem;
274 AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
275 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
276
277 RTMSINTERVAL cMilliesInitial = cMillies;
278 uint64_t tsStart = 0;
279 if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
280 tsStart = RTTimeNanoTS();
281
282#ifdef RTSEMRW_STRICT
283 RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt();
284 if (cMillies > 0)
285 {
286 int rc9;
287 if (pThis->hWriter != NIL_RTTHREAD && pThis->hWriter == RTThreadNativeSelf())
288 rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
289 else
290 rc9 = RTLockValidatorRecSharedCheckOrder(&pThis->ValidatorRead, hThreadSelf, pSrcPos, cMillies);
291 if (RT_FAILURE(rc9))
292 return rc9;
293 }
294#endif
295
296 /*
297 * Take critsect.
298 */
299 int rc = RTCritSectEnter(&pThis->CritSect);
300 if (RT_FAILURE(rc))
301 {
302 AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
303 return rc;
304 }
305
306 /*
307 * Check if the state of affairs allows read access.
308 * Do not block further readers if there is a writer waiting, as
309 * that will break/deadlock reader recursion.
310 */
311 if ( pThis->hWriter == NIL_RTNATIVETHREAD
312#if 0
313 && ( !pThis->cWritesWaiting
314 || pThis->cReads)
315#endif
316 )
317 {
318 pThis->cReads++;
319 Assert(pThis->cReads > 0);
320#ifdef RTSEMRW_STRICT
321 RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
322#endif
323
324 RTCritSectLeave(&pThis->CritSect);
325 return VINF_SUCCESS;
326 }
327
328 RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
329 if (pThis->hWriter == hNativeSelf)
330 {
331#ifdef RTSEMRW_STRICT
332 int rc9 = RTLockValidatorRecExclRecursionMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core, pSrcPos);
333 if (RT_FAILURE(rc9))
334 {
335 RTCritSectLeave(&pThis->CritSect);
336 return rc9;
337 }
338#endif
339
340 pThis->cWriterReads++;
341 Assert(pThis->cWriterReads > 0);
342
343 RTCritSectLeave(&pThis->CritSect);
344 return VINF_SUCCESS;
345 }
346
347 RTCritSectLeave(&pThis->CritSect);
348
349 /*
350 * Wait till it's ready for reading.
351 */
352 if (cMillies == 0)
353 return VERR_TIMEOUT;
354
355#ifndef RTSEMRW_STRICT
356 RTTHREAD hThreadSelf = RTThreadSelf();
357#endif
358 for (;;)
359 {
360 if (cMillies != RT_INDEFINITE_WAIT)
361 {
362 int64_t tsDelta = RTTimeNanoTS() - tsStart;
363 if (tsDelta >= 1000000)
364 {
365 tsDelta /= 1000000;
366 if ((uint64_t)tsDelta < cMilliesInitial)
367 cMilliesInitial = (RTMSINTERVAL)tsDelta;
368 else
369 cMilliesInitial = 1;
370 }
371 }
372#ifdef RTSEMRW_STRICT
373 rc = RTLockValidatorRecSharedCheckBlocking(&pThis->ValidatorRead, hThreadSelf, pSrcPos, true,
374 cMillies, RTTHREADSTATE_RW_READ, false);
375 if (RT_FAILURE(rc))
376 break;
377#else
378 RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_READ, false);
379 RT_NOREF_PV(pSrcPos);
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 repeat 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
443RTDECL(int) RTSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
444{
445#ifndef RTSEMRW_STRICT
446 return rtSemRWRequestRead(hRWSem, cMillies, false, NULL);
447#else
448 RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
449 return rtSemRWRequestRead(hRWSem, cMillies, false, &SrcPos);
450#endif
451}
452RT_EXPORT_SYMBOL(RTSemRWRequestRead);
453
454
455RTDECL(int) RTSemRWRequestReadDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
456{
457 RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
458 return rtSemRWRequestRead(hRWSem, cMillies, false, &SrcPos);
459}
460RT_EXPORT_SYMBOL(RTSemRWRequestReadDebug);
461
462
463RTDECL(int) RTSemRWRequestReadNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
464{
465#ifndef RTSEMRW_STRICT
466 return rtSemRWRequestRead(hRWSem, cMillies, true, NULL);
467#else
468 RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
469 return rtSemRWRequestRead(hRWSem, cMillies, true, &SrcPos);
470#endif
471}
472RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResume);
473
474
475RTDECL(int) RTSemRWRequestReadNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
476{
477 RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
478 return rtSemRWRequestRead(hRWSem, cMillies, true, &SrcPos);
479}
480RT_EXPORT_SYMBOL(RTSemRWRequestReadNoResumeDebug);
481
482
483RTDECL(int) RTSemRWReleaseRead(RTSEMRW hRWSem)
484{
485 struct RTSEMRWINTERNAL *pThis = hRWSem;
486
487 /*
488 * Validate handle.
489 */
490 AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
491 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
492
493 /*
494 * Take critsect.
495 */
496 int rc = RTCritSectEnter(&pThis->CritSect);
497 if (RT_SUCCESS(rc))
498 {
499 if (pThis->hWriter == NIL_RTNATIVETHREAD)
500 {
501#ifdef RTSEMRW_STRICT
502 rc = RTLockValidatorRecSharedCheckAndRelease(&pThis->ValidatorRead, NIL_RTTHREAD);
503 if (RT_SUCCESS(rc))
504#endif
505 {
506 if (RT_LIKELY(pThis->cReads > 0))
507 {
508 pThis->cReads--;
509
510 /* Kick off a writer if appropriate. */
511 if ( pThis->cWritesWaiting > 0
512 && !pThis->cReads)
513 {
514 rc = RTSemEventSignal(pThis->WriteEvent);
515 AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", hRWSem, rc));
516 }
517 }
518 else
519 {
520 AssertFailed();
521 rc = VERR_NOT_OWNER;
522 }
523 }
524 }
525 else
526 {
527 RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
528 if (pThis->hWriter == hNativeSelf)
529 {
530 if (pThis->cWriterReads > 0)
531 {
532#ifdef RTSEMRW_STRICT
533 rc = RTLockValidatorRecExclUnwindMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core);
534 if (RT_SUCCESS(rc))
535#endif
536 {
537 pThis->cWriterReads--;
538 }
539 }
540 else
541 {
542 AssertFailed();
543 rc = VERR_NOT_OWNER;
544 }
545 }
546 else
547 {
548 AssertFailed();
549 rc = VERR_NOT_OWNER;
550 }
551 }
552
553 RTCritSectLeave(&pThis->CritSect);
554 }
555 else
556 AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
557
558 return rc;
559}
560RT_EXPORT_SYMBOL(RTSemRWReleaseRead);
561
562
563DECL_FORCE_INLINE(int) rtSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
564{
565 /*
566 * Validate handle.
567 */
568 struct RTSEMRWINTERNAL *pThis = hRWSem;
569 AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
570 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
571
572 RTMSINTERVAL cMilliesInitial = cMillies;
573 uint64_t tsStart = 0;
574 if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
575 tsStart = RTTimeNanoTS();
576
577#ifdef RTSEMRW_STRICT
578 RTTHREAD hThreadSelf = NIL_RTTHREAD;
579 if (cMillies)
580 {
581 hThreadSelf = RTThreadSelfAutoAdopt();
582 int rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
583 if (RT_FAILURE(rc9))
584 return rc9;
585 }
586#endif
587
588 /*
589 * Take critsect.
590 */
591 int rc = RTCritSectEnter(&pThis->CritSect);
592 if (RT_FAILURE(rc))
593 {
594 AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
595 return rc;
596 }
597
598 /*
599 * Check if the state of affairs allows write access.
600 */
601 RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
602 if ( !pThis->cReads
603 && ( ( !pThis->cWrites
604 && ( !pThis->cWritesWaiting /* play fair if we can wait */
605 || !cMillies)
606 )
607 || pThis->hWriter == hNativeSelf
608 )
609 )
610 {
611 /*
612 * Reset the reader event semaphore if necessary.
613 */
614 if (pThis->fNeedResetReadEvent)
615 {
616 pThis->fNeedResetReadEvent = false;
617 rc = RTSemEventMultiReset(pThis->ReadEvent);
618 AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", hRWSem, rc));
619 }
620
621 pThis->cWrites++;
622 pThis->hWriter = hNativeSelf;
623#ifdef RTSEMRW_STRICT
624 RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, pThis->cWrites == 1);
625#endif
626 RTCritSectLeave(&pThis->CritSect);
627 return VINF_SUCCESS;
628 }
629
630 /*
631 * Signal writer presence.
632 */
633 if (cMillies != 0)
634 pThis->cWritesWaiting++;
635
636 RTCritSectLeave(&pThis->CritSect);
637
638 /*
639 * Wait till it's ready for writing.
640 */
641 if (cMillies == 0)
642 return VERR_TIMEOUT;
643
644#ifndef RTSEMRW_STRICT
645 RTTHREAD hThreadSelf = RTThreadSelf();
646#endif
647 for (;;)
648 {
649 if (cMillies != RT_INDEFINITE_WAIT)
650 {
651 int64_t tsDelta = RTTimeNanoTS() - tsStart;
652 if (tsDelta >= 1000000)
653 {
654 tsDelta /= 1000000;
655 if ((uint64_t)tsDelta < cMilliesInitial)
656 cMilliesInitial = (RTMSINTERVAL)tsDelta;
657 else
658 cMilliesInitial = 1;
659 }
660 }
661
662#ifdef RTSEMRW_STRICT
663 rc = RTLockValidatorRecExclCheckBlocking(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true,
664 cMillies, RTTHREADSTATE_RW_WRITE, false);
665 if (RT_FAILURE(rc))
666 break;
667#else
668 RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_WRITE, false);
669 RT_NOREF_PV(pSrcPos);
670#endif
671 int rcWait;
672 if (fInterruptible)
673 rcWait = rc = RTSemEventWaitNoResume(pThis->WriteEvent, cMillies);
674 else
675 rcWait = rc = RTSemEventWait(pThis->WriteEvent, cMillies);
676 RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_WRITE);
677 if (RT_UNLIKELY(RT_FAILURE_NP(rc) && rc != VERR_TIMEOUT)) /* timeouts are handled below */
678 {
679 AssertMsgRC(rc, ("RTSemEventWait failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
680 break;
681 }
682
683 if (RT_UNLIKELY(pThis->u32Magic != RTSEMRW_MAGIC))
684 {
685 rc = VERR_SEM_DESTROYED;
686 break;
687 }
688
689 /*
690 * Re-take critsect and repeat the check we did prior to this loop.
691 */
692 rc = RTCritSectEnter(&pThis->CritSect);
693 if (RT_FAILURE(rc))
694 {
695 AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
696 break;
697 }
698
699 if (!pThis->cReads && (!pThis->cWrites || pThis->hWriter == hNativeSelf))
700 {
701 /*
702 * Reset the reader event semaphore if necessary.
703 */
704 if (pThis->fNeedResetReadEvent)
705 {
706 pThis->fNeedResetReadEvent = false;
707 rc = RTSemEventMultiReset(pThis->ReadEvent);
708 AssertMsgRC(rc, ("Failed to reset readers, rwsem %p, rc=%Rrc.\n", hRWSem, rc));
709 }
710
711 pThis->cWrites++;
712 pThis->hWriter = hNativeSelf;
713 pThis->cWritesWaiting--;
714#ifdef RTSEMRW_STRICT
715 RTLockValidatorRecExclSetOwner(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, true);
716#endif
717
718 RTCritSectLeave(&pThis->CritSect);
719 return VINF_SUCCESS;
720 }
721
722 RTCritSectLeave(&pThis->CritSect);
723
724 /*
725 * Quit if the wait already timed out.
726 */
727 if (rcWait == VERR_TIMEOUT)
728 {
729 rc = VERR_TIMEOUT;
730 break;
731 }
732 }
733
734 /*
735 * Timeout/error case, clean up.
736 */
737 if (pThis->u32Magic == RTSEMRW_MAGIC)
738 {
739 RTCritSectEnter(&pThis->CritSect);
740 /* Adjust this counter, whether we got the critsect or not. */
741 pThis->cWritesWaiting--;
742 RTCritSectLeave(&pThis->CritSect);
743 }
744 return rc;
745}
746
747
748RTDECL(int) RTSemRWRequestWrite(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
749{
750#ifndef RTSEMRW_STRICT
751 return rtSemRWRequestWrite(hRWSem, cMillies, false, NULL);
752#else
753 RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
754 return rtSemRWRequestWrite(hRWSem, cMillies, false, &SrcPos);
755#endif
756}
757RT_EXPORT_SYMBOL(RTSemRWRequestWrite);
758
759
760RTDECL(int) RTSemRWRequestWriteDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
761{
762 RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
763 return rtSemRWRequestWrite(hRWSem, cMillies, false, &SrcPos);
764}
765RT_EXPORT_SYMBOL(RTSemRWRequestWriteDebug);
766
767
768RTDECL(int) RTSemRWRequestWriteNoResume(RTSEMRW hRWSem, RTMSINTERVAL cMillies)
769{
770#ifndef RTSEMRW_STRICT
771 return rtSemRWRequestWrite(hRWSem, cMillies, true, NULL);
772#else
773 RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_NORMAL_API();
774 return rtSemRWRequestWrite(hRWSem, cMillies, true, &SrcPos);
775#endif
776}
777RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResume);
778
779
780RTDECL(int) RTSemRWRequestWriteNoResumeDebug(RTSEMRW hRWSem, RTMSINTERVAL cMillies, RTHCUINTPTR uId, RT_SRC_POS_DECL)
781{
782 RTLOCKVALSRCPOS SrcPos = RTLOCKVALSRCPOS_INIT_DEBUG_API();
783 return rtSemRWRequestWrite(hRWSem, cMillies, true, &SrcPos);
784}
785RT_EXPORT_SYMBOL(RTSemRWRequestWriteNoResumeDebug);
786
787
788RTDECL(int) RTSemRWReleaseWrite(RTSEMRW hRWSem)
789{
790
791 /*
792 * Validate handle.
793 */
794 struct RTSEMRWINTERNAL *pThis = hRWSem;
795 AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
796 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
797
798 /*
799 * Take critsect.
800 */
801 int rc = RTCritSectEnter(&pThis->CritSect);
802 AssertRCReturn(rc, rc);
803
804 /*
805 * Check if owner.
806 */
807 RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
808 if (pThis->hWriter != hNativeSelf)
809 {
810 RTCritSectLeave(&pThis->CritSect);
811 AssertMsgFailed(("Not read-write owner of rwsem %p.\n", hRWSem));
812 return VERR_NOT_OWNER;
813 }
814
815#ifdef RTSEMRW_STRICT
816 if (pThis->cWrites > 1 || !pThis->cWriterReads) /* don't check+release if VERR_WRONG_ORDER */
817 {
818 int rc9 = RTLockValidatorRecExclReleaseOwner(&pThis->ValidatorWrite, pThis->cWrites == 1);
819 if (RT_FAILURE(rc9))
820 {
821 RTCritSectLeave(&pThis->CritSect);
822 return rc9;
823 }
824 }
825#endif
826
827 /*
828 * Release ownership and remove ourselves from the writers count.
829 */
830 Assert(pThis->cWrites > 0);
831 pThis->cWrites--;
832 if (!pThis->cWrites)
833 {
834 if (RT_UNLIKELY(pThis->cWriterReads > 0))
835 {
836 pThis->cWrites++;
837 RTCritSectLeave(&pThis->CritSect);
838 AssertMsgFailed(("All recursive read locks need to be released prior to the final write lock! (%p)n\n", pThis));
839 return VERR_WRONG_ORDER;
840 }
841
842 pThis->hWriter = NIL_RTNATIVETHREAD;
843 }
844
845 /*
846 * Release the readers if no more writers waiting, otherwise the writers.
847 */
848 if (!pThis->cWritesWaiting)
849 {
850 rc = RTSemEventMultiSignal(pThis->ReadEvent);
851 AssertMsgRC(rc, ("RTSemEventMultiSignal failed for rwsem %p, rc=%Rrc.\n", hRWSem, rc));
852 pThis->fNeedResetReadEvent = true;
853 }
854 else
855 {
856 rc = RTSemEventSignal(pThis->WriteEvent);
857 AssertMsgRC(rc, ("Failed to signal writers on rwsem %p, rc=%Rrc\n", hRWSem, rc));
858 }
859 RTCritSectLeave(&pThis->CritSect);
860
861 return rc;
862}
863RT_EXPORT_SYMBOL(RTSemRWReleaseWrite);
864
865
866RTDECL(bool) RTSemRWIsWriteOwner(RTSEMRW hRWSem)
867{
868 /*
869 * Validate handle.
870 */
871 struct RTSEMRWINTERNAL *pThis = hRWSem;
872 AssertPtrReturn(pThis, false);
873 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, false);
874
875 /*
876 * Check ownership.
877 */
878 RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
879 RTNATIVETHREAD hWriter;
880 ASMAtomicUoReadHandle(&pThis->hWriter, &hWriter);
881 return hWriter == hNativeSelf;
882}
883RT_EXPORT_SYMBOL(RTSemRWIsWriteOwner);
884
885
886RTDECL(bool) RTSemRWIsReadOwner(RTSEMRW hRWSem, bool fWannaHear)
887{
888 /*
889 * Validate handle.
890 */
891 struct RTSEMRWINTERNAL *pThis = hRWSem;
892 AssertPtrReturn(pThis, false);
893 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, false);
894
895 /*
896 * Check write ownership. The writer is also a valid reader.
897 */
898 RTNATIVETHREAD hNativeSelf = RTThreadNativeSelf();
899 RTNATIVETHREAD hWriter;
900 ASMAtomicUoReadHandle(&pThis->hWriter, &hWriter);
901 if (hWriter == hNativeSelf)
902 return true;
903 if (hWriter != NIL_RTNATIVETHREAD)
904 return false;
905
906#ifdef RTSEMRW_STRICT
907 /*
908 * Ask the lock validator.
909 */
910 NOREF(fWannaHear);
911 return RTLockValidatorRecSharedIsOwner(&pThis->ValidatorRead, NIL_RTTHREAD);
912#else
913 /*
914 * If there are no reads we cannot be one of them... But if there are we
915 * cannot know and can only return what the caller want to hear.
916 */
917 if (pThis->cReads == 0)
918 return false;
919 return fWannaHear;
920#endif
921}
922RT_EXPORT_SYMBOL(RTSemRWIsReadOwner);
923
924
925RTDECL(uint32_t) RTSemRWGetWriteRecursion(RTSEMRW hRWSem)
926{
927 struct RTSEMRWINTERNAL *pThis = hRWSem;
928
929 /*
930 * Validate handle.
931 */
932 AssertPtrReturn(pThis, 0);
933 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, 0);
934
935 /*
936 * Return the requested data.
937 */
938 return pThis->cWrites;
939}
940RT_EXPORT_SYMBOL(RTSemRWGetWriteRecursion);
941
942
943RTDECL(uint32_t) RTSemRWGetWriterReadRecursion(RTSEMRW hRWSem)
944{
945 struct RTSEMRWINTERNAL *pThis = hRWSem;
946
947 /*
948 * Validate handle.
949 */
950 AssertPtrReturn(pThis, 0);
951 AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, 0);
952
953 /*
954 * Return the requested data.
955 */
956 return pThis->cWriterReads;
957}
958RT_EXPORT_SYMBOL(RTSemRWGetWriterReadRecursion);
959
960
961RTDECL(uint32_t) RTSemRWGetReadCount(RTSEMRW hRWSem)
962{
963 /*
964 * Validate input.
965 */
966 struct RTSEMRWINTERNAL *pThis = hRWSem;
967 AssertPtrReturn(pThis, 0);
968 AssertMsgReturn(pThis->u32Magic == RTSEMRW_MAGIC,
969 ("pThis=%p u32Magic=%#x\n", pThis, pThis->u32Magic),
970 0);
971
972 /*
973 * Return the requested data.
974 */
975 return pThis->cReads;
976}
977RT_EXPORT_SYMBOL(RTSemRWGetReadCount);
978
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