/*
* Copyright by the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.bitcoinj.store;
import sun.misc.*;
import sun.nio.ch.*;
import java.nio.*;
/**
* <p>This class knows how to force an mmap'd ByteBuffer to reliquish its file handles before it becomes garbage collected,
* by exploiting implementation details of the HotSpot JVM implementation.</p>
*
* <p>This is required on Windows because otherwise an attempt to delete a file that is still mmapped will fail. This can
* happen when a user requests a "restore from seed" function, which involves deleting and recreating the chain file.
* At some point we should stop using mmap in SPVBlockStore and we can then delete this class.</p>
*
* <p>It is a separate class to avoid hitting unknown imports when running on other JVMs.</p>
*/
public class WindowsMMapHack {
public static void forceRelease(MappedByteBuffer buffer) {
Cleaner cleaner = ((DirectBuffer) buffer).cleaner();
if (cleaner != null) cleaner.clean();
}
}