/**
* Gets the sequence number associated with a block location.<br>
* <br>
* If soft is true, this method counts as a volatile read. Otherwise, it is both a volatile read
* and a volatile write.<br>
* <br>
* Soft reads should only be used for the first of the 2 step process for confirming that data
* hasn't changed.
*
* @param x the x coordinate
* @param y the y coordinate
* @param z the z coordinate
* @return the sequence number, or DatatableSequenceNumber.ATOMIC for a single short record
*/
@Override
public int getSequence(int x, int y, int z) {
checkCompressing();
int index = getIndex(x, y, z);
int spins = 0;
boolean interrupted = false;
try {
while (true) {
if (spins++ > SPINS) {
interrupted |= atomicWait(index);
}
checkCompressing();
int blockId = blockIds.get(index);
if (!auxStore.isReserved(blockId)) {
return AtomicSequenceNumber.ATOMIC;
}
int sequence = auxStore.getSequence(blockId);
if (sequence != AtomicSequenceNumber.UNSTABLE) {
return sequence;
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
/**
* Sets the block id, data and auxData for the block at (x, y, z), if the current data matches the
* expected data.<br>
*
* @param x the x coordinate
* @param y the y coordinate
* @param z the z coordinate
* @param expectId the expected block id
* @param expectData the expected block data
* @param expectAuxData the expected block auxiliary data
* @param newId the new block id
* @param newData the new block data
* @param newAuxData the new block auxiliary data
* @return true if the block was set
*/
@Override
public boolean compareAndSetBlock(
int x, int y, int z, short expectId, short expectData, short newId, short newData) {
int index = getIndex(x, y, z);
int spins = 0;
boolean interrupted = false;
try {
while (true) {
if (spins++ > SPINS) {
interrupted |= atomicWait(index);
}
checkCompressing();
short oldBlockId = blockIds.get(index);
boolean oldReserved = auxStore.isReserved(oldBlockId);
if (!oldReserved) {
if (blockIds.get(index) != expectId || expectData != 0) {
return false;
}
} else {
int seq = auxStore.getSequence(oldBlockId);
short oldId = auxStore.getId(oldBlockId);
short oldData = auxStore.getData(oldBlockId);
if (!testSequence(x, y, z, seq)) {
continue;
}
if (oldId != expectId || oldData != expectData) {
return false;
}
}
if (newData == 0 && !auxStore.isReserved(newId)) {
if (!blockIds.compareAndSet(index, oldBlockId, newId)) {
continue;
}
} else {
int newIndex = auxStore.add(newId, newData);
if (!blockIds.compareAndSet(index, oldBlockId, (short) newIndex)) {
auxStore.remove(newIndex);
continue;
}
}
if (oldReserved) {
auxStore.remove(oldBlockId);
}
markDirty(x, y, z);
return true;
}
} finally {
atomicNotify(index);
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
