/*
* This file is part of the Heritrix web crawler (crawler.archive.org).
*
* Licensed to the Internet Archive (IA) by one or more individual
* contributors.
*
* The IA 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.archive.crawler.frontier;
import java.io.IOException;
import com.sleepycat.bind.serial.ClassCatalog;
import com.sleepycat.bind.serial.SerialBinding;
import com.sleepycat.bind.serial.SerialOutput;
import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.util.FastOutputStream;
import com.sleepycat.util.RuntimeExceptionWrapper;
/**
* A SerialBinding that recycles a single FastOutputStream per
* thread, avoiding reallocation of the internal buffer for
* either repeated serializations or because of mid-serialization
* expansions. (Cached stream's buffer will quickly grow to a size
* sufficient for all serialized instances.)
*
* @author gojomo
*/
public class RecyclingSerialBinding<K> extends SerialBinding<K> {
/**
* Thread-local cache of reusable FastOutputStream
*/
protected ThreadLocal<FastOutputStream> fastOutputStreamHolder
= new ThreadLocal<FastOutputStream>();
private ClassCatalog classCatalog;
private Class<K> baseClass;
/**
* Constructor. Save parameters locally, as superclass
* fields are private.
*
* @param classCatalog is the catalog to hold shared class information
*
* @param baseClass is the base class for serialized objects stored using
* this binding
*/
@SuppressWarnings("unchecked")
public RecyclingSerialBinding(ClassCatalog classCatalog, Class baseClass) {
super(classCatalog, baseClass);
this.classCatalog = classCatalog;
this.baseClass = baseClass;
}
/**
* Copies superclass simply to allow different source for FastOoutputStream.
*
* @see com.sleepycat.bind.serial.SerialBinding#entryToObject
*/
public void objectToEntry(Object object, DatabaseEntry entry) {
if (baseClass != null && !baseClass.isInstance(object)) {
throw new IllegalArgumentException(
"Data object class (" + object.getClass() +
") not an instance of binding's base class (" +
baseClass + ')');
}
FastOutputStream fo = getFastOutputStream();
try {
SerialOutput jos = new SerialOutput(fo, classCatalog);
jos.writeObject(object);
} catch (IOException e) {
throw new RuntimeExceptionWrapper(e);
}
byte[] hdr = SerialOutput.getStreamHeader();
entry.setData(fo.getBufferBytes(), hdr.length,
fo.getBufferLength() - hdr.length);
}
/**
* Get the cached (and likely pre-grown to efficient size) FastOutputStream,
* creating it if necessary.
*
* @return FastOutputStream
*/
private FastOutputStream getFastOutputStream() {
FastOutputStream fo = (FastOutputStream) fastOutputStreamHolder.get();
if (fo == null) {
fo = new FastOutputStream();
fastOutputStreamHolder.set(fo);
}
fo.reset();
return fo;
}
}