int32 BufferPool::tryGetBuffer(uint32* bid)
{
int32 ret = 0;
// lock mutex for reset
MutexLocker ml(&_mutexReset);
// decrement free buffers counter
ret = _semFree.tryWait();
if (ret == FAILURE)
return FAILURE;
DataBuf* buf = (DataBuf*) _psFree.pop();
if (!buf) {
puts("Critical: null buffer in pool"); return FAILURE;
}
*bid = buf->getBID();
// increment used buffers counter
_semUsed.post();
// ok
return SUCCESS;
}
uint32 BufferPool::getBuffer(void)
{
DataBuf* buf = NULL;
// lock mutex for reset
MutexLocker ml(&_mutexReset);
// decrement free buffers counter
_semFree.wait();
// get bid from stack
buf = (DataBuf *) _psFree.pop();
// check if there are no more free buffers
if (!buf) {
fprintf(stderr, "BufferPool: NO MORE FREE BUFFERS...\n");
return 0;
}
// increment used buffers counter
_semUsed.post();
// return this bid
return buf->getBID();
}
void BufferPool::reset(void)
{
DataBuf* buf = NULL;
int32 ret = 0;
// lock mutex for reset
MutexLocker ml(&_mutexReset);
// empty buffers stack
for (uint32 j = 0; j < _bcount; j++) {
buf = (DataBuf *) _psFree.pop();
if (!buf)
break;
UOSUTIL_DOUT(("Get buffer from the stack: %u\n", buf->getBID()));
}
// reset "used" semaphore
while ((ret = _semUsed.tryWait()) != FAILURE)
UOSUTIL_DOUT(("Waiting on semaphore \"used\"\n"));
// reset "free" semaphore
while ((ret = _semFree.tryWait()) != FAILURE)
UOSUTIL_DOUT(("Waiting on semaphore \"free\"\n"));
// put all buffers in the buffers stack
for (uint32 i = 0; i < _bcount; i++) {
// reset buffer
_bufs[i]->setInUse(false);
_bufs[i]->setCount(0);
// push buffer pointer into the "free buffers" stack
_psFree.push(_bufs[i]);
// DEBUG
UOSUTIL_DOUT(("Buffer %u pushed.\n", _bufs[i]->getBID()));
}
// reset "free" semaphore
for (uint32 k = 0; k < _bcount; k++) {
UOSUTIL_DOUT(("Posting semaphore \"free\" (%u)\n", k));
_semFree.post();
}
}
BufferPool::~BufferPool(void)
{
uint32 bid = 0, i = 0;
uint32 wait = 10, bc = 0;
MutexLocker ml(&_mutexReset);
/*
* Here we must free the unlocked buffers first,
* then wait some time for further buffers that will
* be freed by worker threads.
*/
while (bc < _bcount && i++ < wait) {
DataBuf* buf = (DataBuf*) _psFree.pop();
if (buf) {
// get buffer id
bid = buf->getBID();
// free selected buffer
delete _bufs[bid];
// reset pointer
_bufs[bid] = NULL;
// count freed buffers
bc++;
} else {
// wait some time
Thread::sleep(50);
}
}
/*
* Timeout expired, so check which buffers are not
* returned home.
*/
for (i = 0; i < _bcount; i++) {
if (_bufs[i]) {
// DEBUG
UOSUTIL_DOUT(("BufferPool: Buffer %d is NOT NULL\n", i));
if (!_bufs[i]->isInUse()) {
// DEBUG
UOSUTIL_DOUT(("BufferPool: Buffer %d is NOT IN USE\n", i));
UOSUTIL_DOUT(("BufferPool: Buffer %d will be DELETED\n", i));
delete _bufs[i];
} else {
// DEBUG
UOSUTIL_DOUT(("BufferPool: Buffer %d is IN USE: leaked\n", i));
}
} else {
// DEBUG
UOSUTIL_DOUT(("BufferPool: Buffer %d is NULL, ignored\n", i));
}
}
/*
* Delete other objects.
*/
delete[] _bufs;
}
