com.sun.jna

Class CallbackThreadInitializer

java.lang.Object

com.sun.jna.CallbackThreadInitializer

public class CallbackThreadInitializer
extends Object

This class provides for customization of the mapping of native threads onto attached Java threads. Use Native.setCallbackThreadInitializer(com.sun.jna.Callback, com.sun.jna.CallbackThreadInitializer) 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 Native.detach(boolean) 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.

Constructor Summary

Constructors

Constructor and Description
CallbackThreadInitializer() The default initializer causes the callback thread to remain attached as a daemon thread, using the default thread name and group.
CallbackThreadInitializer(boolean daemon) Keep the callback thread attached, with the given daemon state, using the default thread name and group.
CallbackThreadInitializer(boolean daemon, boolean detach) Uses the default thread name and group.
CallbackThreadInitializer(boolean daemon, boolean detach, String name) Uses the default thread group.
CallbackThreadInitializer(boolean daemon, boolean detach, String name, ThreadGroup group) Specify all aspects of how the callback thread should be initialized.

Method Summary

Modifier and Type	Method and Description
boolean	detach(Callback cb) Returns whether the Thread should be detached from the VM after the callback exits, if the thread was not already attached to begin with.
String	getName(Callback cb) Returns the desired name for this thread, or null for the default.
ThreadGroup	getThreadGroup(Callback cb) Returns the desired ThreadGroup for thread, or null for the default.
boolean	isDaemon(Callback cb) Returns whether the callback thread should be a daemon thread.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CallbackThreadInitializer

public CallbackThreadInitializer()

The default initializer causes the callback thread to remain attached as a daemon thread, using the default thread name and group.

CallbackThreadInitializer

public CallbackThreadInitializer(boolean daemon)

Keep the callback thread attached, with the given daemon state, using the default thread name and group.

CallbackThreadInitializer

public CallbackThreadInitializer(boolean daemon,
                                 boolean detach)

Uses the default thread name and group.

CallbackThreadInitializer

public CallbackThreadInitializer(boolean daemon,
                                 boolean detach,
                                 String name)

Uses the default thread group.

CallbackThreadInitializer

public CallbackThreadInitializer(boolean daemon,
                                 boolean detach,
                                 String name,
                                 ThreadGroup group)

Specify all aspects of how the callback thread should be initialized.

Method Detail

getName

public String getName(Callback cb)

Returns the desired name for this thread, or null for the default.

getThreadGroup

public ThreadGroup getThreadGroup(Callback cb)

Returns the desired ThreadGroup for thread, or null for the default.

isDaemon

public boolean isDaemon(Callback cb)

Returns whether the callback thread should be a daemon thread.

detach

public boolean detach(Callback cb)

Returns whether the Thread should be detached from the VM after the callback exits, if the thread was not already attached to begin with.