/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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 org.apache.flink.runtime.util;
import org.apache.flink.util.OperatingSystem;
import org.slf4j.Logger;
import sun.misc.Signal;
/**
* This signal handler / signal logger is based on Apache Hadoop's org.apache.hadoop.util.SignalLogger.
*/
public class SignalHandler {
private static boolean registered = false;
/**
* Our signal handler.
*/
private static class Handler implements sun.misc.SignalHandler {
private final Logger LOG;
private final sun.misc.SignalHandler prevHandler;
Handler(String name, Logger LOG) {
this.LOG = LOG;
prevHandler = Signal.handle(new Signal(name), this);
}
/**
* Handle an incoming signal.
*
* @param signal The incoming signal
*/
@Override
public void handle(Signal signal) {
LOG.info("RECEIVED SIGNAL {}: SIG{}. Shutting down as requested.",
signal.getNumber(),
signal.getName());
prevHandler.handle(signal);
}
}
/**
* Register some signal handlers.
*
* @param LOG The slf4j logger
*/
public static void register(final Logger LOG) {
synchronized (SignalHandler.class) {
if (registered) {
return;
}
registered = true;
final String[] SIGNALS = OperatingSystem.isWindows()
? new String[]{ "TERM", "INT"}
: new String[]{ "TERM", "HUP", "INT" };
StringBuilder bld = new StringBuilder();
bld.append("Registered UNIX signal handlers for [");
String separator = "";
for (String signalName : SIGNALS) {
try {
new Handler(signalName, LOG);
bld.append(separator);
bld.append(signalName);
separator = ", ";
} catch (Exception e) {
LOG.info("Error while registering signal handler", e);
}
}
bld.append("]");
LOG.info(bld.toString());
}
}
}