/**
* Licensed to Cloudera, Inc. under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. Cloudera, Inc. 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 com.cloudera.flume.reporter.sampler;
import java.io.IOException;
import java.util.Random;
import com.cloudera.flume.conf.Context;
import com.cloudera.flume.conf.SinkFactory.SinkDecoBuilder;
import com.cloudera.flume.core.Event;
import com.cloudera.flume.core.EventSink;
import com.cloudera.flume.core.EventSinkDecorator;
import com.cloudera.util.Clock;
import com.google.common.base.Preconditions;
/**
* This sampler works by specifying the probability (double between 0.0 and 1.0)
* that a message will be forwarded to the decorated sink. (e.g. .90 means 9 out
* of 10 message will be forwarded)
*/
public class ProbabilitySampler<S extends EventSink> extends
EventSinkDecorator<S> {
double prob;
Random rand;
public ProbabilitySampler(S s, double prob, long seed) {
super(s);
this.prob = prob;
this.rand = new Random(seed);
}
public ProbabilitySampler(S s, double prob) {
this(s, prob, Clock.unixTime());
}
@Override
public void append(Event e) throws IOException, InterruptedException {
if (rand.nextDouble() < prob) {
getSink().append(e);
}
}
public static SinkDecoBuilder builder() {
return new SinkDecoBuilder() {
@Override
public EventSinkDecorator<EventSink> build(Context context,
String... argv) {
Preconditions.checkArgument(argv.length == 1 || argv.length == 2,
"usage: probabilitySampler(prob[, seed])");
double prob = Double.parseDouble(argv[0]);
long seed = Clock.unixTime();
if (argv.length == 2) {
seed = Long.parseLong(argv[1]);
}
return new ProbabilitySampler<EventSink>(null, prob, seed);
}
};
}
}