com.sun.jna.CallbackThreadInitializer Maven / Gradle / Ivy
/* Copyright (c) 2011 Timothy Wall, All Rights Reserved
*
* The contents of this file is dual-licensed under 2
* alternative Open Source/Free licenses: LGPL 2.1 or later and
* Apache License 2.0. (starting with JNA version 4.0.0).
*
* You can freely decide which license you want to apply to
* the project.
*
* You may obtain a copy of the LGPL License at:
*
* http://www.gnu.org/licenses/licenses.html
*
* A copy is also included in the downloadable source code package
* containing JNA, in file "LGPL2.1".
*
* You may obtain a copy of the Apache License at:
*
* http://www.apache.org/licenses/
*
* A copy is also included in the downloadable source code package
* containing JNA, in file "AL2.0".
*/
/**This class provides for customization of the mapping of native threads
* onto attached Java threads. Use
* {@link Native#setCallbackThreadInitializer} to customize the thread context
* in which a given callback is invoked.
* When a JNA callback is invoked on a native thread that is not currently
* tracked by the VM and a CallbackThreadInitiailizer is
* registered for that callback, the initializer object will be used to
* determine how the thread should be attached to the VM.
* Once attached, the method {@link Native#detach} may be used from within
* the callback invocation to alter whether the thread will be detached or not
* when the callback finishes execution. Typically this functionality is used
* in situations where you expect a callback to be called repeatedly from the
* same thread and you want to avoid potential extra thread allocation
* overhead on each callback invocation, since the VM may or may not re-use
* the same allocated thread object each time the thread is attached.
* A single initializer may be used for multiple callbacks, one initializer
* per callback, or you may subclass the initializer to provide different
* initializer settings depending on the callback.
*/
package com.sun.jna;
public class CallbackThreadInitializer {
private boolean daemon;
private boolean detach;
private String name;
private ThreadGroup group;
/** The default initializer causes the callback thread to remain attached
as a daemon thread, using the default thread name and group.
*/
public CallbackThreadInitializer() {
this(true);
}
/** Keep the callback thread attached, with the given daemon state,
using the default thread name and group.
*/
public CallbackThreadInitializer(boolean daemon) {
this(daemon, false);
}
/** Uses the default thread name and group. */
public CallbackThreadInitializer(boolean daemon, boolean detach) {
this(daemon, detach, null);
}
/** Uses the default thread group. */
public CallbackThreadInitializer(boolean daemon, boolean detach, String name) {
this(daemon, detach, name, null);
}
/** Specify all aspects of how the callback thread should be initialized. */
public CallbackThreadInitializer(boolean daemon, boolean detach, String name, ThreadGroup group) {
this.daemon = daemon;
this.detach = detach;
this.name = name;
this.group = group;
}
/** Returns the desired name for this thread, or null for the default. */
public String getName(Callback cb) { return name; }
/** Returns the desired ThreadGroup for thread, or null for the default. */
public ThreadGroup getThreadGroup(Callback cb) { return group; }
/** Returns whether the callback thread should be a daemon thread. */
public boolean isDaemon(Callback cb) { return daemon; }
/** Returns whether the Thread should be detached from the VM after the
callback exits, if the thread was not already attached to begin with.
*/
public boolean detach(Callback cb) { return detach; }
}