void ReadWriteLock::Release(WriteGuard&)
{
KS_ASSERT(mWriteEntryThread == GetCurrentThreadId() && mReentrancyCount >= 0);
int reentrants = mReentrancyCount > 0 ? atomic_decrement((u32*)&mReentrancyCount) + 1 : 0;
if (reentrants == 0)
{
mWriteEntryThread = 0;
const u32 lock_key(EXCL_ENCODE(exclusive_write, 0));
if (atomic_compare_and_swap(&mMutualExclusivityMask, lock_key, exclusive_none) != lock_key)
{
KS_ASSERT( ! "ReadWriteLockException::eAlreadyUnlocked" );
}
}
}
WriteGuard ReadWriteLock::Write()
{
const ThreadID threadID = GetCurrentThreadId();
const u32 lock_key(EXCL_ENCODE(exclusive_write, 0));
while (atomic_compare_and_swap(&mMutualExclusivityMask, exclusive_none, lock_key) != exclusive_none)
{
if (threadID == mWriteEntryThread)
{
atomic_increment((u32*)&mReentrancyCount);
break;
}
cond_wait();
}
KS_ASSERT(mWriteEntryThread == 0 || mWriteEntryThread == threadID);
mWriteEntryThread = threadID;
return WriteGuard(this);
}
void ReadWriteLock::Release(ReadGuard&)
{
const u32 lock_key = EXCL_ENCODE(exclusive_write, 0);
u32 mutual_mask = mMutualExclusivityMask;
u32 current_key = mutual_mask & READ_COUNT_MASK;
u32 exit_key = current_key - 1;
while (atomic_compare_and_swap(&mMutualExclusivityMask, current_key, exit_key) != current_key )
{
if (mutual_mask == lock_key && mWriteEntryThread == GetCurrentThreadId()) // it's a re-entrant read
{
int rentrants = atomic_decrement((u32*)&mReentrancyCount);
KS_ASSERT(rentrants >= 0);
break;
}
cond_wait();
mutual_mask = mMutualExclusivityMask;
current_key = mutual_mask & READ_COUNT_MASK;
exit_key = current_key - 1;
}
}
ReadWriteLock::~ReadWriteLock()
{
KS_ASSERT( mMutualExclusivityMask == 0 );
}
void *GPUBuffer::map(unsigned byte_size, unsigned access /*= GL_MAP_WRITE_BIT | GL_MAP_INVALIDATE_BUFFER_BIT*/)
{
KS_ASSERT(byte_size <= m_size);
bind();
return glMapBufferRange(m_target, 0, byte_size, access);
}
