/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.jackrabbit.core.value;
import java.io.InputStream;
import javax.jcr.RepositoryException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* <code>RefCountingBLOBFileValue</code> implements a reference counting BLOB
* file value on top of an existing {@link BLOBFileValue}. Whenever a
* {@link #copy()} is created from this BLOB file value, a new light weight
* {@link RefCountBinary} is created and the reference count {@link #refCount}
* is incremented. The underlying value is discarded once this
* {@link RefCountingBLOBFileValue} and all its light weight
* {@link RefCountBinary} instances have been discarded.
*/
public class RefCountingBLOBFileValue extends BLOBFileValue {
/**
* The logger instance for this class.
*/
private static final Logger log = LoggerFactory.getLogger(RefCountingBLOBFileValue.class);
/**
* The actual value.
*/
private final BLOBFileValue value;
/**
* The current ref count. Initially set to one.
*/
private int refCount = 1;
/**
* Whether this instance has been discarded and cannot be used anymore.
*/
private boolean disposed = false;
/**
* Creates a new reference counting blob file value based on the given
* <code>value</code>.
*
* @param value the underlying value.
*/
public RefCountingBLOBFileValue(BLOBFileValue value) {
this.value = value;
}
//----------------------------< BLOBFileValue >-----------------------------
/**
* Discards the underlying value if the reference count drops to zero.
*/
public synchronized void dispose() {
if (refCount > 0) {
if (--refCount == 0) {
log.debug("{}@refCount={}, discarding value...",
System.identityHashCode(this), refCount);
value.dispose();
disposed = true;
} else {
log.debug("{}@refCount={}",
System.identityHashCode(this), refCount);
}
}
}
/**
* Forwards the call to the underlying value.
*
* @param pruneEmptyParentDirs if <code>true</code>, empty parent
* directories will automatically be deleted
*/
@Override
void delete(boolean pruneEmptyParentDirs) {
value.delete(pruneEmptyParentDirs);
}
/**
* Returns a light weight copy of this BLOB file value.
*
* @return a copy of this value.
* @throws RepositoryException if an error occurs while creating the copy or
* if this value has been disposed already.
*/
@Override
synchronized BLOBFileValue copy() throws RepositoryException {
if (refCount <= 0) {
throw new RepositoryException("this BLOBFileValue has been disposed");
}
BLOBFileValue bin = new RefCountBinary();
refCount++;
log.debug("{}@refCount={}", System.identityHashCode(this), refCount);
return bin;
}
public boolean equals(Object obj) {
if (obj instanceof RefCountingBLOBFileValue) {
RefCountingBLOBFileValue val = (RefCountingBLOBFileValue) obj;
return value.equals(val.value);
}
return false;
}
public String toString() {
return value.toString();
}
public int hashCode() {
return 0;
}
//-----------------------------------------------------< javax.jcr.Binary >
public long getSize() throws RepositoryException {
return value.getSize();
}
public InputStream getStream() throws RepositoryException {
return value.getStream();
}
@Override
protected void finalize() throws Throwable {
if (!disposed) {
dispose();
}
super.finalize();
}
//------------------------< RefCountBinary >--------------------------------
private final class RefCountBinary extends BLOBFileValue {
private boolean disposed;
public InputStream getStream() throws RepositoryException {
checkDisposed();
return getInternalValue().getStream();
}
public long getSize() throws RepositoryException {
checkDisposed();
return getInternalValue().getSize();
}
public void dispose() {
if (!disposed) {
disposed = true;
getInternalValue().dispose();
}
}
@Override
void delete(boolean pruneEmptyParentDirs) {
getInternalValue().delete(pruneEmptyParentDirs);
}
@Override
BLOBFileValue copy() throws RepositoryException {
checkDisposed();
return getInternalValue().copy();
}
public boolean equals(Object obj) {
if (obj instanceof RefCountBinary) {
RefCountBinary other = (RefCountBinary) obj;
return getInternalValue().equals(other.getInternalValue());
}
return false;
}
public String toString() {
return getInternalValue().toString();
}
public int hashCode() {
return 0;
}
@Override
protected void finalize() throws Throwable {
dispose();
super.finalize();
}
private BLOBFileValue getInternalValue() {
return RefCountingBLOBFileValue.this;
}
private void checkDisposed() throws RepositoryException {
if (disposed) {
throw new RepositoryException("this BLOBFileValue is disposed");
}
}
}
}