jep.python.PyPointer Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of jep Show documentation
Jep embeds CPython in Java through JNI.
There is a newer version: 4.2.1
/**
 * Copyright (c) 2017-2022 JEP AUTHORS.
 *
 * This file is licensed under the the zlib/libpng License.
 *
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event will the authors be held liable for any
 * damages arising from the use of this software.
 * 
 * Permission is granted to anyone to use this software for any
 * purpose, including commercial applications, and to alter it and
 * redistribute it freely, subject to the following restrictions:
 * 
 *     1. The origin of this software must not be misrepresented; you
 *     must not claim that you wrote the original software. If you use
 *     this software in a product, an acknowledgment in the product
 *     documentation would be appreciated but is not required.
 * 
 *     2. Altered source versions must be plainly marked as such, and
 *     must not be misrepresented as being the original software.
 * 
 *     3. This notice may not be removed or altered from any source
 *     distribution.
 */
package jep.python;

import java.lang.ref.WeakReference;

import jep.JepException;

/**
 * Contains pointers to a JepThread* and a PyObject* for using a PyObject* in
 * Java as a PyObject or its subclasses.
 * 
 *
 * @author Nate Jensen
 * @since 3.8
 */
public class PyPointer extends WeakReference {

    protected final long pyObject;

    protected final MemoryManager memoryManager;

    protected volatile boolean disposed;

    /**
     * Constructor
     * 
     * @param referrent
     *            the PyObject (or subclass) corresponding to this PyPointer
     * @param memoryManager
     *            the MemoryManager responsible for tracking this pointer
     * @param pyObject
     *            the pointer to the PyObject*
     * @throws JepException
     *             if an error occurs
     */
    protected PyPointer(PyObject referrent, MemoryManager memoryManager,
            long pyObject) throws JepException {
        super(referrent, memoryManager.getReferenceQueue());
        this.pyObject = pyObject;
        this.memoryManager = memoryManager;
        this.memoryManager.addReference(this);
        disposed = false;
    }

    /**
     * Decrefs the PyObject* associated with this PyPointer. When a Python
     * object reaches zero references, it is available for Python garbage
     * collection.
     * 
     * @throws JepException
     *             if an error occurs
     */
    protected synchronized void dispose() throws JepException {
        if (!disposed) {
            disposed = true;
            decref(memoryManager.getThreadState(), pyObject);
            memoryManager.removeReference(this);
        }
    }

    protected boolean isDisposed() {
        return disposed;
    }

    private native void decref(long tstate, long pyObject) throws JepException;

}