Examples with SSTableScanner org.apache.cassandra.io.sstable.SSTableScanner used on opensource projects

Example 1 with SSTableScanner

use of org.apache.cassandra.io.sstable.SSTableScanner in project eiger by wlloyd.

the class RowIteratorFactory method getIterator.

/**
     * Get a row iterator over the provided memtables and sstables, between the provided keys
     * and filtered by the queryfilter.
     * @param memtables Memtables pending flush.
     * @param sstables SStables to scan through.
     * @param startWith Start at this key
     * @param stopAt Stop and this key
     * @param filter Used to decide which columns to pull out
     * @param cfs
     * @return A row iterator following all the given restrictions
     */
public static CloseableIterator<Row> getIterator(final Iterable<Memtable> memtables, final Collection<SSTableReader> sstables, final RowPosition startWith, final RowPosition stopAt, final QueryFilter filter, final ColumnFamilyStore cfs) {
    // fetch data from current memtable, historical memtables, and SSTables in the correct order.
    final List<CloseableIterator<IColumnIterator>> iterators = new ArrayList<CloseableIterator<IColumnIterator>>();
    // memtables
    for (Memtable memtable : memtables) {
        iterators.add(new ConvertToColumnIterator(filter, memtable.getEntryIterator(startWith, stopAt)));
    }
    for (SSTableReader sstable : sstables) {
        final SSTableScanner scanner = sstable.getScanner(filter);
        scanner.seekTo(startWith);
        // otherwise we leak FDs
        assert scanner instanceof Closeable;
        iterators.add(scanner);
    }
    // reduce rows from all sources into a single row
    return MergeIterator.get(iterators, COMPARE_BY_KEY, new MergeIterator.Reducer<IColumnIterator, Row>() {

        private final int gcBefore = (int) (System.currentTimeMillis() / 1000) - cfs.metadata.getGcGraceSeconds();

        private final List<IColumnIterator> colIters = new ArrayList<IColumnIterator>();

        private DecoratedKey key;

        private ColumnFamily returnCF;

        @Override
        protected void onKeyChange() {
            this.returnCF = ColumnFamily.create(cfs.metadata);
        }

        public void reduce(IColumnIterator current) {
            this.colIters.add(current);
            this.key = current.getKey();
            this.returnCF.delete(current.getColumnFamily());
        }

        protected Row getReduced() {
            // First check if this row is in the rowCache. If it is we can skip the rest
            ColumnFamily cached = cfs.getRawCachedRow(key);
            if (cached == null)
                // not cached: collate
                filter.collateColumns(returnCF, colIters, gcBefore);
            else {
                QueryFilter keyFilter = new QueryFilter(key, filter.path, filter.filter);
                returnCF = cfs.filterColumnFamily(cached, keyFilter, gcBefore);
            }
            Row rv = new Row(key, returnCF);
            colIters.clear();
            key = null;
            return rv;
        }
    });
}