Examples with KeySelector org.janusgraph.diskstorage.keycolumnvalue.keyvalue.KeySelector used on opensource projects

Example 1 with KeySelector

use of org.janusgraph.diskstorage.keycolumnvalue.keyvalue.KeySelector in project janusgraph by JanusGraph.

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);
    final Transaction tx = getTransaction(txh);
    final StaticBuffer keyStart = query.getStart();
    final StaticBuffer keyEnd = query.getEnd();
    final KeySelector selector = query.getKeySelector();
    final List<KeyValueEntry> result = new ArrayList<>();
    final DatabaseEntry foundKey = keyStart.as(ENTRY_FACTORY);
    final DatabaseEntry foundData = new DatabaseEntry();
    try (final Cursor 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));
        }
    } catch (Exception e) {
        throw new PermanentBackendException(e);
    }
    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();
        }
    };
}