/**
* 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.handlers.debug;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;
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.google.common.base.Preconditions;
/**
* This decorator adds a latch hook that will block the sink until the latch is
* triggered. Again this is for allowing different error conditions to be
* triggered.
*
* Allow precount events to pass first.
*
* Then latch until trigger is called the specified number of times.
*
* Afterwards, just work.
*
* TODO (jon) this isn't completely thought out.
*/
public class LatchedDecorator<S extends EventSink> extends
EventSinkDecorator<S> {
final CountDownLatch latch;
final int pre;
final AtomicInteger precount;
public LatchedDecorator(S s, int pre, int count) {
super(s);
this.latch = new CountDownLatch(count);
this.pre = pre;
this.precount = new AtomicInteger(pre);
}
@Override
public void append(Event e) throws IOException, InterruptedException {
if (precount.get() > 0) {
precount.decrementAndGet();
} else {
try {
latch.await();
} catch (InterruptedException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
super.append(e);
}
/**
* This decrements the latch counter the impede's progress
*/
public void trigger() {
latch.countDown();
}
public static SinkDecoBuilder builder() {
return new SinkDecoBuilder() {
@Override
public EventSinkDecorator<EventSink> build(Context context,
String... argv) {
Preconditions.checkArgument(argv.length <= 2,
"usage: latch([init=1,[pre=0]])");
int mult = 1;
int pre = 0;
if (argv.length >= 1)
mult = Integer.parseInt(argv[0]);
if (argv.length >= 2)
pre = Integer.parseInt(argv[1]);
return new LatchedDecorator<EventSink>(null, pre, mult);
}
};
}
}