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/*
* Copyright (C) 2010 The Guava Authors
*
* 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.google.common.util.concurrent;
import static java.util.logging.Level.SEVERE;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.annotations.VisibleForTesting;
import java.lang.Thread.UncaughtExceptionHandler;
import java.util.Locale;
/**
* Factories for {@link UncaughtExceptionHandler} instances.
*
* @author Gregory Kick
* @since 8.0
*/
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
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.
*
* <p>Example usage:
*
* <pre>
* public static void main(String[] args) {
* Thread.currentThread().setUncaughtExceptionHandler(UncaughtExceptionHandlers.systemExit());
* ...
* </pre>
*
* <p>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 LazyLogger logger = new LazyLogger(Exiter.class);
private final Runtime runtime;
Exiter(Runtime runtime) {
this.runtime = runtime;
}
@Override
public void uncaughtException(Thread t, Throwable e) {
try {
logger
.get()
.log(
SEVERE,
String.format(Locale.ROOT, "Caught an exception in %s. Shutting down.", t),
e);
} catch (Throwable errorInLogging) { // sneaky checked exception
// 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);
}
}
}
}
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