org.rocksdb.AbstractImmutableNativeReference Maven / Gradle / Ivy
// Copyright (c) 2016, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
package org.rocksdb;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* Offers functionality for implementations of
* {@link AbstractNativeReference} which have an immutable reference to the
* underlying native C++ object
*/
//@ThreadSafe
public abstract class AbstractImmutableNativeReference
extends AbstractNativeReference {
/**
* A flag indicating whether the current {@code AbstractNativeReference} is
* responsible to free the underlying C++ object
*/
private final AtomicBoolean owningHandle_;
protected AbstractImmutableNativeReference(final boolean owningHandle) {
this.owningHandle_ = new AtomicBoolean(owningHandle);
}
@Override
public boolean isOwningHandle() {
return owningHandle_.get();
}
/**
* Releases this {@code AbstractNativeReference} from the responsibility of
* freeing the underlying native C++ object
*
* This will prevent the object from attempting to delete the underlying
* native object in its finalizer. This must be used when another object
* takes over ownership of the native object or both will attempt to delete
* the underlying object when garbage collected.
*
* When {@code disOwnNativeHandle()} is called, {@code dispose()} will
* subsequently take no action. As a result, incorrect use of this function
* may cause a memory leak.
*
*
* @see #dispose()
*/
protected final void disOwnNativeHandle() {
owningHandle_.set(false);
}
@Override
public void close() {
if (owningHandle_.compareAndSet(true, false)) {
disposeInternal();
}
}
/**
* The helper function of {@link AbstractImmutableNativeReference#dispose()}
* which all subclasses of {@code AbstractImmutableNativeReference} must
* implement to release their underlying native C++ objects.
*/
protected abstract void disposeInternal();
}