/*
* Copyright © 2014 Cask Data, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package co.cask.cdap.data2.dataset2.lib.table.inmemory;
import co.cask.cdap.api.common.Bytes;
import co.cask.cdap.api.dataset.table.Result;
import co.cask.cdap.api.dataset.table.Row;
import co.cask.cdap.api.dataset.table.Scanner;
import co.cask.cdap.data2.dataset2.lib.table.FuzzyRowFilter;
import com.google.common.collect.Sets;
import java.util.Collections;
import java.util.Iterator;
import java.util.Map;
import java.util.NavigableMap;
import java.util.Set;
import java.util.TreeMap;
/**
* An in-memory implememtation of a scanner.
*/
public class InMemoryScanner implements Scanner {
private final Iterator<Map.Entry<byte[], NavigableMap<byte[], byte[]>>> rows;
private final Set<byte[]> columnsToInclude;
private final FuzzyRowFilter filter;
public InMemoryScanner(Iterator<Map.Entry<byte[], NavigableMap<byte[], byte[]>>> rows) {
this(rows, null, null);
}
public InMemoryScanner(Iterator<Map.Entry<byte[], NavigableMap<byte[], byte[]>>> rows, FuzzyRowFilter filter,
byte[][] columnsToInclude) {
this.rows = rows;
this.filter = filter;
if (columnsToInclude != null) {
this.columnsToInclude = Sets.newTreeSet(Bytes.BYTES_COMPARATOR);
Collections.addAll(this.columnsToInclude, columnsToInclude);
} else {
this.columnsToInclude = null;
}
}
@Override
public Row next() {
Map<byte[], byte[]> columns = new TreeMap<byte[], byte[]>(Bytes.BYTES_COMPARATOR);
Map.Entry<byte[], NavigableMap<byte[], byte[]>> rowEntry = null;
while (columns.isEmpty() && this.rows.hasNext()) {
rowEntry = this.rows.next();
if (filter != null) {
FuzzyRowFilter.ReturnCode code = filter.filterRow(rowEntry.getKey());
if (FuzzyRowFilter.ReturnCode.DONE.equals(code)) {
break; // no more rows can match
} else if (!FuzzyRowFilter.ReturnCode.INCLUDE.equals(code)) {
continue; // this row does not match filter, move to next row
}
}
//Try to read all columns for this row
for (Map.Entry<byte[], byte[]> colEntry : rowEntry.getValue().entrySet()) {
if (columnsToInclude == null || columnsToInclude.contains(colEntry.getKey())) {
columns.put(colEntry.getKey(), colEntry.getValue());
}
}
}
if (columns.size() > 0) {
assert rowEntry != null;
return new Result(rowEntry.getKey(), columns);
} else {
return null;
}
}
@Override
public void close() { /* no op */ }
}