static int rtCritSectRwEnterShared(PRTCRITSECTRW pThis, PCRTLOCKVALSRCPOS pSrcPos, bool fTryOnly)
{
/*
* Validate input.
*/
AssertPtr(pThis);
AssertReturn(pThis->u32Magic == RTCRITSECTRW_MAGIC, VERR_SEM_DESTROYED);
#ifdef IN_RING0
Assert(pThis->fFlags & RTCRITSECT_FLAGS_RING0);
#else
Assert(!(pThis->fFlags & RTCRITSECT_FLAGS_RING0));
#endif
#ifdef RTCRITSECTRW_STRICT
RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt();
if (!fTryOnly)
{
int rc9;
RTNATIVETHREAD hNativeWriter;
ASMAtomicUoReadHandle(&pThis->hNativeWriter, &hNativeWriter);
if (hNativeWriter != NIL_RTTHREAD && hNativeWriter == RTThreadNativeSelf())
rc9 = RTLockValidatorRecExclCheckOrder(pThis->pValidatorWrite, hThreadSelf, pSrcPos, RT_INDEFINITE_WAIT);
else
rc9 = RTLockValidatorRecSharedCheckOrder(pThis->pValidatorRead, hThreadSelf, pSrcPos, RT_INDEFINITE_WAIT);
if (RT_FAILURE(rc9))
return rc9;
}
#endif
/*
* Get cracking...
*/
uint64_t u64State = ASMAtomicReadU64(&pThis->u64State);
uint64_t u64OldState = u64State;
for (;;)
{
if ((u64State & RTCSRW_DIR_MASK) == (RTCSRW_DIR_READ << RTCSRW_DIR_SHIFT))
{
/* It flows in the right direction, try follow it before it changes. */
uint64_t c = (u64State & RTCSRW_CNT_RD_MASK) >> RTCSRW_CNT_RD_SHIFT;
c++;
Assert(c < RTCSRW_CNT_MASK / 2);
u64State &= ~RTCSRW_CNT_RD_MASK;
u64State |= c << RTCSRW_CNT_RD_SHIFT;
if (ASMAtomicCmpXchgU64(&pThis->u64State, u64State, u64OldState))
{
#ifdef RTCRITSECTRW_STRICT
RTLockValidatorRecSharedAddOwner(pThis->pValidatorRead, hThreadSelf, pSrcPos);
#endif
break;
}
}
else if ((u64State & (RTCSRW_CNT_RD_MASK | RTCSRW_CNT_WR_MASK)) == 0)
static int rtSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
{
/*
* Validate input.
*/
RTSEMRWINTERNAL *pThis = hRWSem;
if (pThis == NIL_RTSEMRW)
return VINF_SUCCESS;
AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
#ifdef RTSEMRW_STRICT
RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt();
if (cMillies > 0)
{
int rc9;
RTNATIVETHREAD hNativeWriter;
ASMAtomicUoReadHandle(&pThis->hNativeWriter, &hNativeWriter);
if (hNativeWriter != NIL_RTTHREAD && hNativeWriter == RTThreadNativeSelf())
rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
else
rc9 = RTLockValidatorRecSharedCheckOrder(&pThis->ValidatorRead, hThreadSelf, pSrcPos, cMillies);
if (RT_FAILURE(rc9))
return rc9;
}
#endif
/*
* Get cracking...
*/
uint64_t u64State = ASMAtomicReadU64(&pThis->u64State);
uint64_t u64OldState = u64State;
for (;;)
{
if ((u64State & RTSEMRW_DIR_MASK) == (RTSEMRW_DIR_READ << RTSEMRW_DIR_SHIFT))
{
/* It flows in the right direction, try follow it before it changes. */
uint64_t c = (u64State & RTSEMRW_CNT_RD_MASK) >> RTSEMRW_CNT_RD_SHIFT;
c++;
Assert(c < RTSEMRW_CNT_MASK / 2);
u64State &= ~RTSEMRW_CNT_RD_MASK;
u64State |= c << RTSEMRW_CNT_RD_SHIFT;
if (ASMAtomicCmpXchgU64(&pThis->u64State, u64State, u64OldState))
{
#ifdef RTSEMRW_STRICT
RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
#endif
break;
}
}
else if ((u64State & (RTSEMRW_CNT_RD_MASK | RTSEMRW_CNT_WR_MASK)) == 0)
DECL_FORCE_INLINE(int) rtSemRWRequestRead(RTSEMRW hRWSem, RTMSINTERVAL cMillies, bool fInterruptible, PCRTLOCKVALSRCPOS pSrcPos)
{
/*
* Validate handle.
*/
struct RTSEMRWINTERNAL *pThis = hRWSem;
AssertPtrReturn(pThis, VERR_INVALID_HANDLE);
AssertReturn(pThis->u32Magic == RTSEMRW_MAGIC, VERR_INVALID_HANDLE);
RTMSINTERVAL cMilliesInitial = cMillies;
uint64_t tsStart = 0;
if (cMillies != RT_INDEFINITE_WAIT && cMillies != 0)
tsStart = RTTimeNanoTS();
#ifdef RTSEMRW_STRICT
RTTHREAD hThreadSelf = RTThreadSelfAutoAdopt();
if (cMillies > 0)
{
int rc9;
if (pThis->hWriter != NIL_RTTHREAD && pThis->hWriter == RTThreadNativeSelf())
rc9 = RTLockValidatorRecExclCheckOrder(&pThis->ValidatorWrite, hThreadSelf, pSrcPos, cMillies);
else
rc9 = RTLockValidatorRecSharedCheckOrder(&pThis->ValidatorRead, hThreadSelf, pSrcPos, cMillies);
if (RT_FAILURE(rc9))
return rc9;
}
#endif
/*
* Take critsect.
*/
int rc = RTCritSectEnter(&pThis->CritSect);
if (RT_FAILURE(rc))
{
AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
return rc;
}
/*
* Check if the state of affairs allows read access.
* Do not block further readers if there is a writer waiting, as
* that will break/deadlock reader recursion.
*/
if ( pThis->hWriter == NIL_RTNATIVETHREAD
#if 0
&& ( !pThis->cWritesWaiting
|| pThis->cReads)
#endif
)
{
pThis->cReads++;
Assert(pThis->cReads > 0);
#ifdef RTSEMRW_STRICT
RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
#endif
RTCritSectLeave(&pThis->CritSect);
return VINF_SUCCESS;
}
RTNATIVETHREAD hNativeSelf = pThis->CritSect.NativeThreadOwner;
if (pThis->hWriter == hNativeSelf)
{
#ifdef RTSEMRW_STRICT
int rc9 = RTLockValidatorRecExclRecursionMixed(&pThis->ValidatorWrite, &pThis->ValidatorRead.Core, pSrcPos);
if (RT_FAILURE(rc9))
{
RTCritSectLeave(&pThis->CritSect);
return rc9;
}
#endif
pThis->cWriterReads++;
Assert(pThis->cWriterReads > 0);
RTCritSectLeave(&pThis->CritSect);
return VINF_SUCCESS;
}
RTCritSectLeave(&pThis->CritSect);
/*
* Wait till it's ready for reading.
*/
if (cMillies == 0)
return VERR_TIMEOUT;
#ifndef RTSEMRW_STRICT
RTTHREAD hThreadSelf = RTThreadSelf();
#endif
for (;;)
{
if (cMillies != RT_INDEFINITE_WAIT)
{
int64_t tsDelta = RTTimeNanoTS() - tsStart;
if (tsDelta >= 1000000)
{
tsDelta /= 1000000;
if ((uint64_t)tsDelta < cMilliesInitial)
cMilliesInitial = (RTMSINTERVAL)tsDelta;
else
cMilliesInitial = 1;
}
}
#ifdef RTSEMRW_STRICT
rc = RTLockValidatorRecSharedCheckBlocking(&pThis->ValidatorRead, hThreadSelf, pSrcPos, true,
cMillies, RTTHREADSTATE_RW_READ, false);
if (RT_FAILURE(rc))
break;
#else
RTThreadBlocking(hThreadSelf, RTTHREADSTATE_RW_READ, false);
#endif
int rcWait;
if (fInterruptible)
rcWait = rc = RTSemEventMultiWaitNoResume(pThis->ReadEvent, cMillies);
else
rcWait = rc = RTSemEventMultiWait(pThis->ReadEvent, cMillies);
RTThreadUnblocked(hThreadSelf, RTTHREADSTATE_RW_READ);
if (RT_FAILURE(rc) && rc != VERR_TIMEOUT) /* handle timeout below */
{
AssertMsgRC(rc, ("RTSemEventMultiWait failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
break;
}
if (pThis->u32Magic != RTSEMRW_MAGIC)
{
rc = VERR_SEM_DESTROYED;
break;
}
/*
* Re-take critsect and repeat the check we did before the loop.
*/
rc = RTCritSectEnter(&pThis->CritSect);
if (RT_FAILURE(rc))
{
AssertMsgFailed(("RTCritSectEnter failed on rwsem %p, rc=%Rrc\n", hRWSem, rc));
break;
}
if ( pThis->hWriter == NIL_RTNATIVETHREAD
#if 0
&& ( !pThis->cWritesWaiting
|| pThis->cReads)
#endif
)
{
pThis->cReads++;
Assert(pThis->cReads > 0);
#ifdef RTSEMRW_STRICT
RTLockValidatorRecSharedAddOwner(&pThis->ValidatorRead, hThreadSelf, pSrcPos);
#endif
RTCritSectLeave(&pThis->CritSect);
return VINF_SUCCESS;
}
RTCritSectLeave(&pThis->CritSect);
/*
* Quit if the wait already timed out.
*/
if (rcWait == VERR_TIMEOUT)
{
rc = VERR_TIMEOUT;
break;
}
}
/* failed */
return rc;
}