/**
* Atomically gets the full set of data associated with the block.<br>
* <br>
*
* @param x the x coordinate
* @param y the y coordinate
* @param z the z coordinate
* @return the full state of the block
*/
@Override
public int getFullData(int x, int y, int z) {
int index = getIndex(x, y, z);
int spins = 0;
boolean interrupted = false;
try {
while (true) {
if (spins++ > SPINS) {
interrupted |= atomicWait(index);
}
checkCompressing();
int seq = getSequence(x, y, z);
short blockId = blockIds.get(index);
if (auxStore.isReserved(blockId)) {
int state = auxStore.getInt(blockId);
if (testSequence(x, y, z, seq)) {
return state;
}
} else {
int state = BlockFullState.getPacked(blockId, (short) 0);
return state;
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
/**
* Gets the block id for a block at a particular location.<br>
* <br>
* Block ids range from 0 to 65535.
*
* @param x the x coordinate
* @param y the y coordinate
* @param z the z coordinate
* @return the block id
*/
@Override
public int getBlockId(int x, int y, int z) {
int index = getIndex(x, y, z);
int spins = 0;
boolean interrupted = false;
try {
while (true) {
if (spins++ > SPINS) {
interrupted |= atomicWait(index);
}
checkCompressing();
int seq = getSequence(x, y, z);
short blockId = blockIds.get(index);
if (auxStore.isReserved(blockId)) {
blockId = auxStore.getId(blockId);
if (testSequence(x, y, z, seq)) {
return blockId & 0x0000FFFF;
}
} else {
return blockId & 0x0000FFFF;
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
/**
* 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();
}
}
}
/**
* Copies the block data in the store into an array.<br>
* <br>
* If the store is updated while this snapshot is being taken, data tearing could occur.<br>
* <br>
* If the array is the wrong length or null, a new array is created.
*
* @param the array to place the data
* @return the array
*/
@Override
public short[] getDataArray(short[] array) {
int length = blockIds.length();
if (array == null || array.length != length) {
array = new short[length];
}
for (int i = 0; i < length; i++) {
short blockId = blockIds.get(i);
if (auxStore.isReserved(blockId)) {
array[i] = auxStore.getData(blockId);
} else {
array[i] = 0;
}
}
return array;
}
/** Notifies all waiting threads */
private final void atomicNotify(int index) {
AtomicInteger i = auxStore.getWaiting(index);
if (!i.compareAndSet(0, 0)) {
synchronized (i) {
i.notifyAll();
}
}
}
/**
* Copies the block ids in the store into an array.<br>
* <br>
* If the store is updated while this snapshot is being taken, data tearing could occur.<br>
* <br>
* If the array is the wrong length or null, a new array is created.
*
* @param the array to place the data
* @return the array
*/
@Override
public short[] getBlockIdArray(short[] array) {
int length = blockIds.length();
if (array == null || array.length != length) {
array = new short[length];
}
for (int i = 0; i < length; i++) {
short blockId = blockIds.get(i);
if (auxStore.isReserved(blockId)) {
blockId = auxStore.getId(blockId);
} else {
blockId &= 0x0000FFFF;
}
array[i] = blockId;
}
return array;
}
/**
* Waits until a notify
*
* @return true if interrupted during the wait
*/
private final boolean atomicWait(int index) {
AtomicInteger i = auxStore.getWaiting(index);
i.incrementAndGet();
try {
short blockId = blockIds.get(index);
boolean reserved = auxStore.isReserved(blockId);
synchronized (i) {
if (!reserved || !auxStore.testUnstable(blockId)) {
return false;
}
try {
i.wait();
} catch (InterruptedException e) {
return true;
}
}
} finally {
i.decrementAndGet();
}
return false;
}
/**
* Compresses the auxiliary store.<br>
* <br>
* This method should only be called when the store is guaranteed not to be accessed from any
* other thread.<br>
*/
@Override
public void compress() {
if (!compressing.compareAndSet(false, true)) {
throw new IllegalStateException("Compression started while compression was in progress");
}
int length = side * side * side;
AtomicIntArrayStore newAuxStore = new AtomicIntArrayStore(length);
for (int i = 0; i < length; i++) {
short blockId = blockIds.get(i);
if (auxStore.isReserved(blockId)) {
short storedId = auxStore.getId(blockId);
short storedData = auxStore.getData(blockId);
int newIndex = newAuxStore.add(storedId, storedData);
if (!blockIds.compareAndSet(i, blockId, (short) newIndex)) {
throw new IllegalStateException("Unstable block id data during compression step");
}
}
}
auxStore = newAuxStore;
compressing.set(false);
}
/**
* Tests if a the sequence number associated with a particular block location has not changed.
*
* @param x the x coordinate
* @param y the y coordinate
* @param z the z coordinate
* @param expected the expected sequence number
* @return true if the sequence number has not changed and expected is not
* DatatableSequenceNumber.ATOMIC
*/
@Override
public boolean testSequence(int x, int y, int z, int expected) {
if (expected == AtomicSequenceNumber.ATOMIC) {
return false;
}
checkCompressing();
int index = getIndex(x, y, z);
boolean interrupted = false;
try {
checkCompressing();
int blockId = blockIds.get(index);
return auxStore.isReserved(blockId) && auxStore.testSequence(blockId, expected);
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
private int getAndSetBlockRaw(int x, int y, int z, short id, short data) {
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 (data == 0 && !auxStore.isReserved(id)) {
if (!blockIds.compareAndSet(index, oldBlockId, id)) {
continue;
}
} else {
int newIndex = auxStore.add(id, data);
if (!blockIds.compareAndSet(index, oldBlockId, (short) newIndex)) {
auxStore.remove(newIndex);
continue;
}
}
if (oldReserved) {
return auxStore.remove(oldBlockId);
}
return BlockFullState.getPacked(oldBlockId, (short) 0);
}
} finally {
markDirty(x, y, z);
atomicNotify(index);
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
/**
* Gets the number of entries in the store
*
* @return the size of the arrays
*/
public int getEntries() {
checkCompressing();
return auxStore.getEntries();
}
/**
* Gets the size of the internal arrays
*
* @return the size of the arrays
*/
public int getSize() {
checkCompressing();
return auxStore.getSize();
}
/**
* Gets if the store would benefit from compression.<br>
* <br>
* If this method is called when the store is being accessed by another thread, it may give
* spurious results.
*
* @return true if compression would reduce the store size
*/
@Override
public final boolean needsCompression() {
int entries = auxStore.getEntries();
int size = auxStore.getSize();
return auxStore.isAboveMinimumSize() && (entries << 3) / 3 < size;
}
