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/*
* Original Guava code is copyright (C) 2015 The Guava Authors.
* Modifications from Guava are copyright (C) 2016 DiffPlug.
*
* Licensed 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.diffplug.common.util.concurrent;
import static java.util.logging.Level.SEVERE;
import java.lang.Thread.UncaughtExceptionHandler;
import java.util.Locale;
import java.util.logging.Logger;
import com.diffplug.common.annotations.VisibleForTesting;
/**
* Factories for {@link UncaughtExceptionHandler} instances.
*
* @author Gregory Kick
* @since 8.0
*/
public final class UncaughtExceptionHandlers {
private UncaughtExceptionHandlers() {}
/**
* Returns an exception handler that exits the system. This is particularly useful for the main
* thread, which may start up other, non-daemon threads, but fail to fully initialize the
* application successfully.
*
* Example usage:
*
public static void main(String[] args) {
* Thread.currentThread().setUncaughtExceptionHandler(UncaughtExceptionHandlers.systemExit());
* ...
*
*
* The returned handler logs any exception at severity {@code SEVERE} and then shuts down the
* process with an exit status of 1, indicating abnormal termination.
*/
public static UncaughtExceptionHandler systemExit() {
return new Exiter(Runtime.getRuntime());
}
@VisibleForTesting
static final class Exiter implements UncaughtExceptionHandler {
private static final Logger logger = Logger.getLogger(Exiter.class.getName());
private final Runtime runtime;
Exiter(Runtime runtime) {
this.runtime = runtime;
}
@Override
public void uncaughtException(Thread t, Throwable e) {
try {
// cannot use FormattingLogger due to a dependency loop
logger.log(SEVERE,
String.format(Locale.ROOT, "Caught an exception in %s. Shutting down.", t), e);
} catch (Throwable errorInLogging) {
// If logging fails, e.g. due to missing memory, at least try to log the
// message and the cause for the failed logging.
System.err.println(e.getMessage());
System.err.println(errorInLogging.getMessage());
} finally {
runtime.exit(1);
}
}
}
}