io.humble.ferry

Class JNIReference

java.lang.Object

java.lang.ref.Reference<T>

java.lang.ref.WeakReference<Object>

io.humble.ferry.JNIReference

public final class JNIReference
extends WeakReference<Object>

Returned by Buffer.getByteBuffer(int, int, java.util.concurrent.atomic.AtomicReference) for users that want to explicitly manage when the returned ByteBuffer is released.

This class creates a WeakReference that Ferry classes will use for memory management. We do this to avoid relying on Java's finalizer thread to keep up and instead make every new native allocation first release any unreachable objects.

Most times these objects are managed behind the scenes when you call RefCounted.delete(). But when we return ByteBuffer objects, there is no equivalent of delete(), so this object can be used if you want to explicitly control when the ByteBuffer's underlying native memory is freed.

Method Summary

Modifier and Type	Method and Description
void	delete() Explicitly deletes the underlying native storage used by the object this object references.
static JNIMemoryManager	getMgr() Returns the JNIMemoryManager we're using.
String	toString() Creates a string representation of this reference.

Methods inherited from class java.lang.ref.Reference

clear, enqueue, get, isEnqueued

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

getMgr

public static JNIMemoryManager getMgr()

Returns the JNIMemoryManager we're using.

Returns:

the manager

delete

public void delete()

Explicitly deletes the underlying native storage used by the object this object references. The underlying native object is now no long valid, and attempts to use it could cause unspecified behavior.

toString

public String toString()

Creates a string representation of this reference. If the underlying object this reference points to has been deleted, then "native" will be zero. If JNIMemoryManager.isMemoryDebugging() is true, then the class and hashcode of the object this reference points to (or used to point to) is also printed.

If the reference still points to an actual object, we will also print the contents of that object. It may return "null" in which case the underlying object is no longer reachable, but if native != 0, it means it has not yet been collected by Ferry.

Overrides:

toString in class Object