Examples with RowQuery com.netflix.astyanax.query.RowQuery used on opensource projects

Example 1 with RowQuery

use of com.netflix.astyanax.query.RowQuery in project janusgraph by JanusGraph.

the class AstyanaxKeyColumnValueStore method getNamesSlice.

public Map<StaticBuffer, EntryList> getNamesSlice(List<StaticBuffer> keys, SliceQuery query, StoreTransaction txh) throws BackendException {
    /*
         * RowQuery<K,C> should be parametrized as
         * RowQuery<ByteBuffer,ByteBuffer>. However, this causes the following
         * compilation error when attempting to call withColumnRange on a
         * RowQuery<ByteBuffer,ByteBuffer> instance:
         *
         * java.lang.Error: Unresolved compilation problem: The method
         * withColumnRange(ByteBuffer, ByteBuffer, boolean, int) is ambiguous
         * for the type RowQuery<ByteBuffer,ByteBuffer>
         *
         * The compiler substitutes ByteBuffer=C for both startColumn and
         * endColumn, compares it to its identical twin with that type
         * hard-coded, and dies.
         *
         */
    // Add one for last column potentially removed in CassandraHelper.makeEntryList
    final int queryLimit = query.getLimit() + (query.hasLimit() ? 1 : 0);
    final int pageLimit = Math.min(this.readPageSize, queryLimit);
    ByteBuffer sliceStart = query.getSliceStart().asByteBuffer();
    final ByteBuffer sliceEnd = query.getSliceEnd().asByteBuffer();
    final RowSliceQuery rq = keyspace.prepareQuery(columnFamily).setConsistencyLevel(getTx(txh).getReadConsistencyLevel().getAstyanax()).withRetryPolicy(retryPolicy.duplicate()).getKeySlice(CassandraHelper.convert(keys));
    // Don't directly chain due to ambiguity resolution; see top comment
    rq.withColumnRange(sliceStart, sliceEnd, false, pageLimit);
    final OperationResult<Rows<ByteBuffer, ByteBuffer>> r;
    try {
        r = (OperationResult<Rows<ByteBuffer, ByteBuffer>>) rq.execute();
    } catch (ConnectionException e) {
        throw new TemporaryBackendException(e);
    }
    final Rows<ByteBuffer, ByteBuffer> rows = r.getResult();
    final Map<StaticBuffer, EntryList> result = new HashMap<>(rows.size());
    for (Row<ByteBuffer, ByteBuffer> row : rows) {
        assert !result.containsKey(row.getKey());
        final ByteBuffer key = row.getKey();
        ColumnList<ByteBuffer> pageColumns = row.getColumns();
        final List<Column<ByteBuffer>> queryColumns = new ArrayList();
        Iterables.addAll(queryColumns, pageColumns);
        while (pageColumns.size() == pageLimit && queryColumns.size() < queryLimit) {
            final Column<ByteBuffer> lastColumn = queryColumns.get(queryColumns.size() - 1);
            sliceStart = lastColumn.getName();
            // No possibility of two values at the same column name, so start the
            // next slice one bit after the last column found by the previous query.
            // byte[] is little-endian
            Integer position = null;
            for (int i = sliceStart.array().length - 1; i >= 0; i--) {
                if (sliceStart.array()[i] < Byte.MAX_VALUE) {
                    position = i;
                    sliceStart.array()[i]++;
                    break;
                }
            }
            if (null == position) {
                throw new PermanentBackendException("Column was not incrementable");
            }
            final RowQuery pageQuery = keyspace.prepareQuery(columnFamily).setConsistencyLevel(getTx(txh).getReadConsistencyLevel().getAstyanax()).withRetryPolicy(retryPolicy.duplicate()).getKey(row.getKey());
            // Don't directly chain due to ambiguity resolution; see top comment
            pageQuery.withColumnRange(sliceStart, sliceEnd, false, pageLimit);
            final OperationResult<ColumnList<ByteBuffer>> pageResult;
            try {
                pageResult = (OperationResult<ColumnList<ByteBuffer>>) pageQuery.execute();
            } catch (ConnectionException e) {
                throw new TemporaryBackendException(e);
            }
            if (Thread.interrupted()) {
                throw new TraversalInterruptedException();
            }
            // Reset the incremented position to avoid leaking mutations up the
            // stack to callers - sliceStart.array() in fact refers to a column name
            // that will be later read to deserialize an edge (since we assigned it
            // via de-referencing a column from the previous query).
            sliceStart.array()[position]--;
            pageColumns = pageResult.getResult();
            Iterables.addAll(queryColumns, pageColumns);
        }
        result.put(StaticArrayBuffer.of(key), CassandraHelper.makeEntryList(queryColumns, entryGetter, query.getSliceEnd(), query.getLimit()));
    }
    return result;
}