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/*
* Copyright (c) 2008-2017, NVIDIA CORPORATION. All rights reserved.
*
* NVIDIA CORPORATION and its licensors retain all intellectual property
* and proprietary rights in and to this software, related documentation
* and any modifications thereto. Any use, reproduction, disclosure or
* distribution of this software and related documentation without an express
* license agreement from NVIDIA CORPORATION is strictly prohibited.
*/
// Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
// Copyright (c) 2001-2004 NovodeX AG. All rights reserved.
#include "ApexRWLockable.h"
#include "PsThread.h"
#include "PsAtomic.h"
#include "ApexSDKIntl.h"
namespace nvidia
{
namespace apex
{
ApexRWLockable::ApexRWLockable()
:
mEnabled (true)
, mCurrentWriter(0)
, mRWLock()
, mConcurrentWriteCount (0)
, mConcurrentReadCount (0)
, mConcurrentErrorCount (0)
{
}
ApexRWLockable::~ApexRWLockable()
{
}
void ApexRWLockable::setEnabled(bool e)
{
mEnabled = e;
}
bool ApexRWLockable::isEnabled() const
{
return mEnabled;
}
void ApexRWLockable::acquireReadLock(const char*, uint32_t) const
{
mRWLock.lockReader();
}
void ApexRWLockable::acquireWriteLock(const char*, uint32_t) const
{
mRWLock.lockWriter();
mCurrentWriter = Thread::getId();
}
void ApexRWLockable::releaseReadLock(void) const
{
mRWLock.unlockReader();
}
void ApexRWLockable::releaseWriteLock(void) const
{
mCurrentWriter = 0;
mRWLock.unlockWriter();
}
bool ApexRWLockable::startWrite(bool allowReentry)
{
PX_COMPILE_TIME_ASSERT(sizeof(ThreadReadWriteCount) == 4);
mDataLock.lock();
bool error = false;
ThreadReadWriteCount& rwc = mData[Thread::getId()];
// check that we are the only thread reading (this allows read->write order on a single thread)
error |= mConcurrentReadCount != rwc.counters.readDepth;
// check no other threads are writing
error |= mConcurrentWriteCount != rwc.counters.writeDepth;
// increment shared write counter
shdfnd::atomicIncrement(&mConcurrentWriteCount);
// in the normal case (re-entry is allowed) then we simply increment
// the writeDepth by 1, otherwise (re-entry is not allowed) increment
// by 2 to force subsequent writes to fail by creating a mismatch between
// the concurrent write counter and the local counter, any value > 1 will do
if (allowReentry)
rwc.counters.writeDepth++;
else
rwc.counters.writeDepth += 2;
mDataLock.unlock();
if (error)
shdfnd::atomicIncrement(&mConcurrentErrorCount);
return !error;
}
void ApexRWLockable::stopWrite(bool allowReentry)
{
shdfnd::atomicDecrement(&mConcurrentWriteCount);
// decrement depth of writes for this thread
mDataLock.lock();
nvidia::ThreadImpl::Id id = nvidia::Thread::getId();
// see comment in startWrite()
if (allowReentry)
mData[id].counters.writeDepth--;
else
mData[id].counters.writeDepth -= 2;
mDataLock.unlock();
}
nvidia::Thread::Id ApexRWLockable::getCurrentWriter() const
{
return mCurrentWriter;
}
bool ApexRWLockable::startRead() const
{
shdfnd::atomicIncrement(&mConcurrentReadCount);
mDataLock.lock();
nvidia::ThreadImpl::Id id = nvidia::Thread::getId();
ThreadReadWriteCount& rwc = mData[id];
rwc.counters.readDepth++;
bool success = (rwc.counters.writeDepth > 0 || mConcurrentWriteCount == 0);
mDataLock.unlock();
if (!success)
shdfnd::atomicIncrement(&mConcurrentErrorCount);
return success;
}
void ApexRWLockable::stopRead() const
{
shdfnd::atomicDecrement(&mConcurrentReadCount);
mDataLock.lock();
nvidia::ThreadImpl::Id id = nvidia::Thread::getId();
mData[id].counters.readDepth--;
mDataLock.unlock();
}
uint32_t ApexRWLockable::getReadWriteErrorCount() const
{
return static_cast<uint32_t>(mConcurrentErrorCount);
}
ApexRWLockableScopedDisable::ApexRWLockableScopedDisable(RWLockable* rw) : mLockable(static_cast<ApexRWLockable*>(rw))
{
mLockable->setEnabled(false);
}
ApexRWLockableScopedDisable::~ApexRWLockableScopedDisable()
{
mLockable->setEnabled(true);
}
ApexRWLockableScopedDisable::ApexRWLockableScopedDisable(const ApexRWLockableScopedDisable& o) : mLockable(o.mLockable)
{
}
ApexRWLockableScopedDisable& ApexRWLockableScopedDisable::operator=(const ApexRWLockableScopedDisable&)
{
return *this;
}
}
}
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