/**
* 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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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.flume.reporter.ReportEvent;
import com.google.common.base.Preconditions;
/**
* This delays turns a sink into a lazy one by delaying opening a node until an
* append attempt is made.
*
* This is thread safe.
*/
public class LazyOpenDecorator<S extends EventSink> extends
EventSinkDecorator<S> {
public static final Logger LOG = LoggerFactory
.getLogger(LazyOpenDecorator.class);
public static final String A_ACTUALLY_OPEN = "actuallyOpen";
public static final String A_LOGICALLY_OPEN = "logicallyOpen";
/**
* open has been called on this sink
*/
boolean logicallyOpen = false;
/**
* open has been called on subsink
*/
boolean actuallyOpen = false;
public LazyOpenDecorator(S s) {
super(s);
}
@Override
public void open() {
Preconditions.checkState(!logicallyOpen,
"Attempting to open already open LazyOpenDeco");
logicallyOpen = true;
}
@Override
public void append(Event e) throws IOException, InterruptedException {
if (logicallyOpen && !actuallyOpen) {
super.open();
actuallyOpen = true;
}
super.append(e);
}
@Override
public void close() throws IOException, InterruptedException {
if (actuallyOpen) {
super.close();
}
if (!logicallyOpen) {
LOG.warn("Closing a lazy sink that was not logically opened");
}
actuallyOpen = false;
logicallyOpen = false;
}
@Override
public ReportEvent getMetrics() {
ReportEvent rpt = super.getMetrics();
rpt.setStringMetric(A_ACTUALLY_OPEN, "" + actuallyOpen);
rpt.setStringMetric(A_LOGICALLY_OPEN, "" + logicallyOpen);
return rpt;
}
public static SinkDecoBuilder builder() {
return new SinkDecoBuilder() {
@Override
public EventSinkDecorator<EventSink> build(Context context,
String... argv) {
Preconditions.checkArgument(argv.length == 0);
return new LazyOpenDecorator<EventSink>(null);
}
};
}
}