/*
* 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.coprocessor.example;
import com.google.protobuf.RpcCallback;
import com.google.protobuf.RpcController;
import com.google.protobuf.Service;
import org.apache.hadoop.hbase.Coprocessor;
import org.apache.hadoop.hbase.CoprocessorEnvironment;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.exceptions.CoprocessorException;
import org.apache.hadoop.hbase.coprocessor.CoprocessorService;
import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
import org.apache.hadoop.hbase.coprocessor.example.generated.ExampleProtos;
import org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter;
import org.apache.hadoop.hbase.protobuf.ResponseConverter;
import org.apache.hadoop.hbase.regionserver.InternalScanner;
import org.apache.hadoop.hbase.util.Bytes;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
/**
* Sample coprocessor endpoint exposing a Service interface for counting rows and key values.
*
* <p>
* For the protocol buffer definition of the RowCountService, see the source file located under
* hbase-server/src/main/protobuf/Examples.proto.
* </p>
*/
public class RowCountEndpoint extends ExampleProtos.RowCountService
implements Coprocessor, CoprocessorService {
private RegionCoprocessorEnvironment env;
public RowCountEndpoint() {
}
/**
* Just returns a reference to this object, which implements the RowCounterService interface.
*/
@Override
public Service getService() {
return this;
}
/**
* Returns a count of the rows in the region where this coprocessor is loaded.
*/
@Override
public void getRowCount(RpcController controller, ExampleProtos.CountRequest request,
RpcCallback<ExampleProtos.CountResponse> done) {
Scan scan = new Scan();
scan.setFilter(new FirstKeyOnlyFilter());
ExampleProtos.CountResponse response = null;
InternalScanner scanner = null;
try {
scanner = env.getRegion().getScanner(scan);
List<KeyValue> results = new ArrayList<KeyValue>();
boolean hasMore = false;
byte[] lastRow = null;
long count = 0;
do {
hasMore = scanner.next(results);
for (KeyValue kv : results) {
byte[] currentRow = kv.getRow();
if (lastRow == null || !Bytes.equals(lastRow, currentRow)) {
lastRow = currentRow;
count++;
}
}
results.clear();
} while (hasMore);
response = ExampleProtos.CountResponse.newBuilder()
.setCount(count).build();
} catch (IOException ioe) {
ResponseConverter.setControllerException(controller, ioe);
} finally {
if (scanner != null) {
try {
scanner.close();
} catch (IOException ignored) {}
}
}
done.run(response);
}
/**
* Returns a count of all KeyValues in the region where this coprocessor is loaded.
*/
@Override
public void getKeyValueCount(RpcController controller, ExampleProtos.CountRequest request,
RpcCallback<ExampleProtos.CountResponse> done) {
ExampleProtos.CountResponse response = null;
InternalScanner scanner = null;
try {
scanner = env.getRegion().getScanner(new Scan());
List<KeyValue> results = new ArrayList<KeyValue>();
boolean hasMore = false;
long count = 0;
do {
hasMore = scanner.next(results);
for (KeyValue kv : results) {
count++;
}
results.clear();
} while (hasMore);
response = ExampleProtos.CountResponse.newBuilder()
.setCount(count).build();
} catch (IOException ioe) {
ResponseConverter.setControllerException(controller, ioe);
} finally {
if (scanner != null) {
try {
scanner.close();
} catch (IOException ignored) {}
}
}
done.run(response);
}
/**
* Stores a reference to the coprocessor environment provided by the
* {@link org.apache.hadoop.hbase.regionserver.RegionCoprocessorHost} from the region where this
* coprocessor is loaded. Since this is a coprocessor endpoint, it always expects to be loaded
* on a table region, so always expects this to be an instance of
* {@link RegionCoprocessorEnvironment}.
* @param env the environment provided by the coprocessor host
* @throws IOException if the provided environment is not an instance of
* {@code RegionCoprocessorEnvironment}
*/
@Override
public void start(CoprocessorEnvironment env) throws IOException {
if (env instanceof RegionCoprocessorEnvironment) {
this.env = (RegionCoprocessorEnvironment)env;
} else {
throw new CoprocessorException("Must be loaded on a table region!");
}
}
@Override
public void stop(CoprocessorEnvironment env) throws IOException {
// nothing to do
}
}