jetbrains.exodus.util.SharedRandomAccessFile Maven / Gradle / Ivy
/**
* Copyright 2010 - 2022 JetBrains s.r.o.
*
* 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
*
* https://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 jetbrains.exodus.util;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.concurrent.atomic.AtomicInteger;
public class SharedRandomAccessFile extends RandomAccessFile {
private final File file;
private final AtomicInteger clients;
public SharedRandomAccessFile(File file, String mode) throws FileNotFoundException {
super(file, mode);
this.file = file;
clients = new AtomicInteger();
}
public File getFile() {
return file;
}
/**
* Employs the file and returns resulting number of its clients.
*
* @return number of clients of the file.
*/
public int employ() {
return clients.incrementAndGet();
}
public void close() throws IOException {
if (clients.getAndDecrement() == 0) {
super.close();
}
}
}