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// Copyright (c) 2011-present, 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.List;
/**
* RocksCallbackObject is similar to {@link RocksObject} but varies
* in its construction as it is designed for Java objects which have functions
* which are called from C++ via JNI.
*
* RocksCallbackObject is the base-class any RocksDB classes that acts as a
* callback from some underlying underlying native C++ {@code rocksdb} object.
*
* The use of {@code RocksObject} should always be preferred over
* {@link RocksCallbackObject} if callbacks are not required.
*/
public abstract class RocksCallbackObject extends
AbstractImmutableNativeReference {
protected final long nativeHandle_;
protected RocksCallbackObject(final long... nativeParameterHandles) {
super(true);
this.nativeHandle_ = initializeNative(nativeParameterHandles);
}
/**
* Given a list of RocksCallbackObjects, it returns a list
* of the native handles of the underlying objects.
*
* @param objectList the rocks callback objects
*
* @return the native handles
*/
static /* @Nullable */ long[] toNativeHandleList(
/* @Nullable */ final List objectList) {
if (objectList == null) {
return new long[0];
}
final int len = objectList.size();
final long[] handleList = new long[len];
for (int i = 0; i < len; i++) {
handleList[i] = objectList.get(i).nativeHandle_;
}
return handleList;
}
/**
* Construct the Native C++ object which will callback
* to our object methods
*
* @param nativeParameterHandles An array of native handles for any parameter
* objects that are needed during construction
*
* @return The native handle of the C++ object which will callback to us
*/
protected abstract long initializeNative(
final long... nativeParameterHandles);
/**
* Deletes underlying C++ native callback object pointer
*/
@Override
protected void disposeInternal() {
disposeInternal(nativeHandle_);
}
private native void disposeInternal(final long handle);
}