org.apache.hadoop.hbase.client.AllowPartialScanResultCache Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hadoop.hbase.client;
import static org.apache.hadoop.hbase.client.ConnectionUtils.filterCells;
import java.io.IOException;
import java.util.List;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
/**
* A ScanResultCache that may return partial result.
*
* As we can only scan from the starting of a row when error, so here we also implement the logic
* that skips the cells that have already been returned.
*/
@InterfaceAudience.Private
class AllowPartialScanResultCache extends ScanResultCache {
// used to filter out the cells that already returned to user as we always start from the
// beginning of a row when retry.
private Cell lastCell;
private boolean lastResultPartial;
public AllowPartialScanResultCache(List cache) {
super(cache);
}
private void recordLastResult(Result result) {
lastCell = result.rawCells()[result.rawCells().length - 1];
lastResultPartial = result.mayHaveMoreCellsInRow();
}
@Override
public void loadResultsToCache(Result[] results, boolean isHeartbeatMessage) throws IOException {
if (results.length == 0) {
if (!isHeartbeatMessage && lastResultPartial) {
// An empty non heartbeat result indicate that there must be a row change. So if the
// lastResultPartial is true then we need to increase numberOfCompleteRows.
numberOfCompleteRows++;
}
return;
}
int i;
for (i = 0; i < results.length; i++) {
Result r = filterCells(results[i], lastCell);
if (r != null) {
results[i] = r;
break;
}
}
if (i == results.length) {
return;
}
if (lastResultPartial && !CellUtil.matchingRow(lastCell, results[0].getRow())) {
// there is a row change, so increase numberOfCompleteRows
numberOfCompleteRows++;
}
recordLastResult(results[results.length - 1]);
addResultArrayToCache(results, i, results.length);
}
@Override
protected void checkUpdateNumberOfCompleteRowsAndCache(Result rs) {
if (!rs.mayHaveMoreCellsInRow()) {
numberOfCompleteRows++;
}
addResultToCache(rs);
}
@Override
public void clear() {
// we do not cache anything
super.clear();
}
}