//
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// Copyright (c) 1995-2020 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under
// the terms of the Eclipse Public License 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0
//
// This Source Code may also be made available under the following
// Secondary Licenses when the conditions for such availability set
// forth in the Eclipse Public License, v. 2.0 are satisfied:
// the Apache License v2.0 which is available at
// https://www.apache.org/licenses/LICENSE-2.0
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// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
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//

package org.eclipse.jetty.util.thread;

import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;

A variation of Executor that can confirm if a thread is available immediately
/** * A variation of Executor that can confirm if a thread is available immediately */
public interface TryExecutor extends Executor {
Attempt to execute a task.
Params:
  • task – The task to be executed
Returns:True IFF the task has been given directly to a thread to execute. The task cannot be queued pending the later availability of a Thread.
/** * Attempt to execute a task. * * @param task The task to be executed * @return True IFF the task has been given directly to a thread to execute. The task cannot be queued pending the later availability of a Thread. */
boolean tryExecute(Runnable task); @Override default void execute(Runnable task) { if (!tryExecute(task)) throw new RejectedExecutionException(); } public static TryExecutor asTryExecutor(Executor executor) { if (executor instanceof TryExecutor) return (TryExecutor)executor; return new NoTryExecutor(executor); } public static class NoTryExecutor implements TryExecutor { private final Executor executor; public NoTryExecutor(Executor executor) { this.executor = executor; } @Override public void execute(Runnable task) { executor.execute(task); } @Override public boolean tryExecute(Runnable task) { return false; } @Override public String toString() { return String.format("%s@%x[%s]", getClass().getSimpleName(), hashCode(), executor); } } TryExecutor NO_TRY = new TryExecutor() { @Override public boolean tryExecute(Runnable task) { return false; } @Override public String toString() { return "NO_TRY"; } }; }