/**
* 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.core;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
import com.cloudera.flume.conf.Context;
import com.cloudera.flume.conf.SinkFactory.SinkDecoBuilder;
import com.cloudera.flume.reporter.ReportEvent;
import com.cloudera.flume.reporter.Reportable;
import com.google.common.base.Preconditions;
/**
* A simple wrapper class that allows for easy extension of EventSinks. (This
* acts like a trait/mixin)
*
* The constructor can allow null sinks as arguments, but append/close/open
* assumes non null.
*
* The decorators have semantics where they act like synchronous functions. When
* there is no buffering and close is just a synchronous call, this is simple,
* just call the child close and return after it returns. If any buffering
* occurs in the decorator, the decorator must flush its contents before
* returning from close.
*/
public class EventSinkDecorator<S extends EventSink> extends EventSink.Base {
protected S sink;
protected AtomicBoolean isOpen = new AtomicBoolean(false);
public EventSinkDecorator(S s) {
// we allow null here to make FlumeBuilder implementation simpler
this.sink = s;
}
@Override
public void append(Event e) throws IOException, InterruptedException {
Preconditions.checkNotNull(sink);
Preconditions.checkState(isOpen.get(), "EventSink " + this.getName()
+ " not open");
sink.append(e);
super.append(e);
}
@Override
public void close() throws IOException, InterruptedException {
Preconditions.checkNotNull(sink);
sink.close();
isOpen.set(false);
}
@Override
public void open() throws IOException, InterruptedException {
Preconditions.checkNotNull(sink);
Preconditions.checkState(!isOpen.get(), "EventSink Decorator was not open");
sink.open();
isOpen.set(true);
}
@Override
public ReportEvent getMetrics() {
ReportEvent rpt = new ReportEvent(getName());
return rpt;
}
@Override
public Map<String, Reportable> getSubMetrics() {
HashMap<String, Reportable> map = new HashMap<String, Reportable>();
map.put(sink.getName(), sink);
return map;
}
@Deprecated
@Override
public void getReports(String namePrefix, Map<String, ReportEvent> reports) {
Preconditions.checkNotNull(sink);
super.getReports(namePrefix, reports);
sink.getReports(namePrefix + getName() + ".", reports);
}
public S getSink() {
return sink;
}
public void setSink(S sink) {
this.sink = sink;
}
public static SinkDecoBuilder nullBuilder() {
return new SinkDecoBuilder() {
@Override
public EventSinkDecorator<EventSink> build(Context context,
String... argv) {
Preconditions.checkArgument(argv.length == 0);
return new EventSinkDecorator<EventSink>(null);
}
};
}
}