com.greenpepper.shaded.com.google.common.util.concurrent.Callables Maven / Gradle / Ivy
/*
* Copyright (C) 2009 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.greenpepper.shaded.com.google.common.util.concurrent;
import static com.greenpepper.shaded.com.google.common.base.Preconditions.checkNotNull;
import com.greenpepper.shaded.com.google.common.annotations.GwtCompatible;
import com.greenpepper.shaded.com.google.common.annotations.GwtIncompatible;
import com.greenpepper.shaded.com.google.common.base.Supplier;
import java.util.concurrent.Callable;
import javax.annotation.Nullable;
/**
* Static utility methods pertaining to the {@link Callable} interface.
*
* @author Isaac Shum
* @since 1.0
*/
@GwtCompatible(emulated = true)
public final class Callables {
private Callables() {}
/**
* Creates a {@code Callable} which immediately returns a preset value each
* time it is called.
*/
public static Callable returning(final @Nullable T value) {
return new Callable() {
@Override public T call() {
return value;
}
};
}
/**
* Wraps the given callable such that for the duration of {@link Callable#call} the thread that is
* running will have the given name.
*
*
* @param callable The callable to wrap
* @param nameSupplier The supplier of thread names, {@link Supplier#get get} will be called once
* for each invocation of the wrapped callable.
*/
@GwtIncompatible("threads")
static Callable threadRenaming(final Callable callable,
final Supplier nameSupplier) {
checkNotNull(nameSupplier);
checkNotNull(callable);
return new Callable() {
@Override public T call() throws Exception {
Thread currentThread = Thread.currentThread();
String oldName = currentThread.getName();
boolean restoreName = trySetName(nameSupplier.get(), currentThread);
try {
return callable.call();
} finally {
if (restoreName) {
trySetName(oldName, currentThread);
}
}
}
};
}
/**
* Wraps the given runnable such that for the duration of {@link Runnable#run} the thread that is
* running with have the given name.
*
*
* @param task The Runnable to wrap
* @param nameSupplier The supplier of thread names, {@link Supplier#get get} will be called once
* for each invocation of the wrapped callable.
*/
@GwtIncompatible("threads")
static Runnable threadRenaming(final Runnable task, final Supplier nameSupplier) {
checkNotNull(nameSupplier);
checkNotNull(task);
return new Runnable() {
@Override public void run() {
Thread currentThread = Thread.currentThread();
String oldName = currentThread.getName();
boolean restoreName = trySetName(nameSupplier.get(), currentThread);
try {
task.run();
} finally {
if (restoreName) {
trySetName(oldName, currentThread);
}
}
}
};
}
/** Tries to set name of the given {@link Thread}, returns true if successful. */
@GwtIncompatible("threads")
private static boolean trySetName(final String threadName, Thread currentThread) {
// In AppEngine this will always fail, should we test for that explicitly using
// MoreExecutors.isAppEngine. More generally, is there a way to see if we have the modifyThread
// permission without catching an exception?
try {
currentThread.setName(threadName);
return true;
} catch (SecurityException e) {
return false;
}
}
}