/**
* 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
*/
public final 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();
}
checkCompressing();
int blockId = blockIds.get(index);
if (!auxStore.isReserved(blockId)) {
return DatatableSequenceNumber.ATOMIC;
} else {
int sequence = auxStore.getSequence(blockId);
if (sequence != DatatableSequenceNumber.UNSTABLE) {
return sequence;
}
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
/**
* Gets the block auxiliary data for a block at a particular location.<br>
* <br>
* Block data ranges from 0 to 65535.
*
* @param x the x coordinate
* @param y the y coordinate
* @param z the z coordinate
* @return the block auxiliary data
*/
public final T getAuxData(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();
}
checkCompressing();
int seq = getSequence(x, y, z);
short blockId = blockIds.get(index);
if (auxStore.isReserved(blockId)) {
T auxData = auxStore.getAuxData(blockId);
if (testSequence(x, y, z, seq)) {
return auxData;
}
} else {
return null;
}
}
} finally {
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
*/
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;
}
/**
* 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
*/
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;
}
/**
* 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
* @param fullState a BlockFullState object to store the return value, or null to generate a new
* one
* @return the full state of the block
*/
public final BlockFullState<T> getFullData(int x, int y, int z, BlockFullState<T> fullData) {
if (fullData == null) {
fullData = new BlockFullState<T>();
}
int index = getIndex(x, y, z);
int spins = 0;
boolean interrupted = false;
try {
while (true) {
if (spins++ > SPINS) {
interrupted |= atomicWait();
}
checkCompressing();
int seq = getSequence(x, y, z);
short blockId = blockIds.get(index);
if (auxStore.isReserved(blockId)) {
fullData.setId(auxStore.getId(blockId));
fullData.setData(auxStore.getData(blockId));
fullData.setAuxData(auxStore.getAuxData(blockId));
if (testSequence(x, y, z, seq)) {
return fullData;
}
} else {
fullData.setId(blockId);
fullData.setData((short) 0);
fullData.setAuxData(null);
return fullData;
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
/**
* 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
*/
public final boolean testSequence(int x, int y, int z, int expected) {
if (expected == DatatableSequenceNumber.ATOMIC) {
return false;
}
checkCompressing();
int index = getIndex(x, y, z);
int spins = 0;
boolean interrupted = false;
try {
if (spins++ > SPINS) {
interrupted |= atomicWait();
}
checkCompressing();
int blockId = blockIds.get(index);
return auxStore.isReserved(blockId) && auxStore.testSequence(blockId, expected);
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
/**
* Sets the block id, data and auxData for the block at (x, y, z).<br>
* <br>
* If the data is 0 and the auxData is null, then the block will be stored as a single short.<br>
*
* @param x the x coordinate
* @param y the y coordinate
* @param z the z coordinate
* @param id the block id
* @param data the block data
* @param auxData the block auxiliary data
*/
public final void setBlock(int x, int y, int z, short id, short data, T auxData) {
int index = getIndex(x, y, z);
int spins = 0;
boolean interrupted = false;
try {
while (true) {
if (spins++ > SPINS) {
interrupted |= atomicWait();
}
checkCompressing();
short oldBlockId = blockIds.get(index);
boolean oldReserved = auxStore.isReserved(oldBlockId);
if (data == 0 && auxData == null && !auxStore.isReserved(id)) {
if (!blockIds.compareAndSet(index, oldBlockId, id)) {
continue;
}
if (oldReserved) {
if (!auxStore.remove(oldBlockId)) {
throw new IllegalStateException(
"setBlock() tried to remove old record, but it had already been removed");
}
}
return;
} else {
int newIndex = auxStore.add(id, data, auxData);
if (!blockIds.compareAndSet(index, oldBlockId, (short) newIndex)) {
if (auxStore.remove(newIndex)) {
throw new IllegalStateException(
"setBlock() tried to remove old record, but it had already been removed");
}
continue;
}
if (oldReserved) {
if (!auxStore.remove(oldBlockId)) {
throw new IllegalStateException(
"setBlock() tried to remove old record, but it had already been removed");
}
}
return;
}
}
} finally {
markDirty(x, y, z);
atomicNotify();
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
/**
* 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>
*/
public final void compress() {
if (!compressing.compareAndSet(false, true)) {
throw new IllegalStateException("Compression started while compression was in progress");
}
int length = side * side * side;
AtomicIntReferenceArrayStore<T> newAuxStore =
new AtomicIntReferenceArrayStore<T>(side * side * side);
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);
T storedAuxData = auxStore.getAuxData(blockId);
int newIndex = newAuxStore.add(storedId, storedData, storedAuxData);
if (!blockIds.compareAndSet(i, blockId, (short) newIndex)) {
throw new IllegalStateException("Unstable block id data during compression step");
}
}
}
auxStore = newAuxStore;
compressing.set(false);
}
/**
* Gets the number of entries in the store
*
* @return the size of the arrays
*/
public final int getEntries() {
checkCompressing();
return auxStore.getEntries();
}
/**
* Gets the size of the internal arrays
*
* @return the size of the arrays
*/
public final 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
*/
public boolean needsCompression() {
return (auxStore.getEntries() << 3) / 3 < auxStore.getSize();
}
/**
* 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
*/
public final boolean compareAndSetBlock(
int x,
int y,
int z,
short expectId,
short expectData,
T expectAuxData,
short newId,
short newData,
T newAuxData) {
int index = getIndex(x, y, z);
int spins = 0;
boolean interrupted = false;
try {
while (true) {
if (spins++ > SPINS) {
interrupted |= atomicWait();
}
checkCompressing();
short oldBlockId = blockIds.get(index);
boolean oldReserved = auxStore.isReserved(oldBlockId);
if (!oldReserved) {
if (blockIds.get(index) != expectId || expectData != 0 || expectAuxData != null) {
return false;
}
} else {
int seq = auxStore.getSequence(oldBlockId);
short oldId = auxStore.getId(oldBlockId);
short oldData = auxStore.getData(oldBlockId);
T oldAuxData = auxStore.getAuxData(oldBlockId);
if (!testSequence(x, y, z, seq)) {
continue;
}
if (oldId != expectId || oldData != expectData || oldAuxData != expectAuxData) {
return false;
}
}
if (newData == 0 && newAuxData == null && !auxStore.isReserved(newId)) {
if (!blockIds.compareAndSet(index, oldBlockId, newId)) {
continue;
}
if (oldReserved) {
if (!auxStore.remove(oldBlockId)) {
throw new IllegalStateException(
"setBlock() tried to remove old record, but it had already been removed");
}
}
markDirty(x, y, z);
return true;
} else {
int newIndex = auxStore.add(newId, newData, newAuxData);
if (!blockIds.compareAndSet(index, oldBlockId, (short) newIndex)) {
if (!auxStore.remove(newIndex)) {
throw new IllegalStateException(
"setBlock() tried to remove old record, but it had already been removed");
}
continue;
}
if (oldReserved) {
if (!auxStore.remove(oldBlockId)) {
throw new IllegalStateException(
"setBlock() tried to remove old record, but it had already been removed");
}
}
markDirty(x, y, z);
return true;
}
}
} finally {
atomicNotify();
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
