use of com.thinkaurelius.titan.diskstorage.keycolumnvalue.keyvalue.KeySelector in project titan by thinkaurelius.
the class BerkeleyJEKeyValueStore method getSlice.
@Override
public RecordIterator<KeyValueEntry> getSlice(KVQuery query, StoreTransaction txh) throws BackendException {
log.trace("beginning db={}, op=getSlice, tx={}", name, txh);
Transaction tx = getTransaction(txh);
Cursor cursor = null;
final StaticBuffer keyStart = query.getStart();
final StaticBuffer keyEnd = query.getEnd();
final KeySelector selector = query.getKeySelector();
final List<KeyValueEntry> result = new ArrayList<KeyValueEntry>();
try {
DatabaseEntry foundKey = keyStart.as(ENTRY_FACTORY);
DatabaseEntry foundData = new DatabaseEntry();
cursor = db.openCursor(tx, null);
OperationStatus status = cursor.getSearchKeyRange(foundKey, foundData, getLockMode(txh));
//Iterate until given condition is satisfied or end of records
while (status == OperationStatus.SUCCESS) {
StaticBuffer key = getBuffer(foundKey);
if (key.compareTo(keyEnd) >= 0)
break;
if (selector.include(key)) {
result.add(new KeyValueEntry(key, getBuffer(foundData)));
}
if (selector.reachedLimit())
break;
status = cursor.getNext(foundKey, foundData, getLockMode(txh));
}
log.trace("db={}, op=getSlice, tx={}, resultcount={}", name, txh, result.size());
return new RecordIterator<KeyValueEntry>() {
private final Iterator<KeyValueEntry> entries = result.iterator();
@Override
public boolean hasNext() {
return entries.hasNext();
}
@Override
public KeyValueEntry next() {
return entries.next();
}
@Override
public void close() {
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
};
} catch (Exception e) {
throw new PermanentBackendException(e);
} finally {
try {
if (cursor != null)
cursor.close();
} catch (Exception e) {
throw new PermanentBackendException(e);
}
}
}
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