/*
* Copyright © 2015 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.etl.common;
import co.cask.cdap.etl.api.Destroyable;
import co.cask.cdap.etl.api.Emitter;
import co.cask.cdap.etl.api.StageMetrics;
import co.cask.cdap.etl.api.Transformation;
import javax.annotation.Nullable;
/**
* A {@link Transformation} that delegates transform operations while emitting metrics
* around how many records were input into the transform and output by it.
*
* @param <IN> Type of input object
* @param <OUT> Type of output object
*/
public class TrackedTransform<IN, OUT> implements Transformation<IN, OUT>, Destroyable {
public static final String RECORDS_IN = "records.in";
public static final String RECORDS_OUT = "records.out";
private final Transformation<IN, OUT> transform;
private final StageMetrics metrics;
private final String metricInName;
private final String metricOutName;
public TrackedTransform(Transformation<IN, OUT> transform, StageMetrics metrics) {
this(transform, metrics, RECORDS_IN, RECORDS_OUT);
}
public TrackedTransform(Transformation<IN, OUT> transform, StageMetrics metrics,
@Nullable String metricInName, @Nullable String metricOutName) {
this.transform = transform;
this.metrics = metrics;
this.metricInName = metricInName;
this.metricOutName = metricOutName;
}
@Override
public void transform(IN input, Emitter<OUT> emitter) throws Exception {
if (metricInName != null) {
metrics.count(metricInName, 1);
}
transform.transform(input, metricOutName == null ? emitter : new TrackedEmitter<>(emitter, metrics, metricOutName));
}
@Override
public void destroy() {
if (transform instanceof Destroyable) {
((Destroyable) transform).destroy();
}
}
}