org.eclipse.jetty.util.thread.PrivilegedThreadFactory Maven / Gradle / Ivy
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//
// ========================================================================
// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//
package org.eclipse.jetty.util.thread;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;
import java.util.function.Supplier;
import org.eclipse.jetty.util.security.SecurityUtils;
/**
* Convenience {@link Thread} factory that ensure threads are
* created without referencing any web application {@link ClassLoader}.
* Up to Java 17, the {@code Thread} constructor was taking a
* snapshot of the calling context, which may contain a {@link ProtectionDomain}
* that references a web application {@code ClassLoader}
* (for example if the creation of the {@code Thread} was triggered
* by some operation performed by the web application).
* The {@code Thread} might then be pooled and prevent the
* web application {@code ClassLoader} to be garbage collected
* when the web application is undeployed.
* For this reason, {@code Thread}s must be created in a privileged
* action, which restricts the calling context to just the caller
* frame, not all the frames in the stack.
* Since Java 18 and the removal of the Java security manager
* and related classes by JEP 411, {@code Thread}s do not retain
* the calling context, so there is no need to create them in a
* privileged action.
*/
class PrivilegedThreadFactory
{
/**
* Creates a new {@link Thread} from the given {@link Supplier},
* without retaining the calling context.
*
* @param creator the action that creates the {@link Thread}
* @return a new {@link Thread} without retaining the calling context
*/
static T newThread(PrivilegedAction creator)
{
return SecurityUtils.doPrivileged(creator);
}
private PrivilegedThreadFactory()
{
}
}