/*
* Copyright (c) 2010-2012 LinkedIn, Inc
*
* 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 krati.core.array.entry;
import java.io.File;
import java.io.IOException;
import org.apache.log4j.Logger;
import krati.io.ChannelReader;
import krati.io.DataReader;
import krati.io.DataWriter;
import krati.io.FastDataWriter;
import krati.util.Chronos;
/**
* Entry.
*
* Transactional Redo Entry.
*
* @author jwu
*
*/
public abstract class AbstractEntry<T extends EntryValue> implements Entry<T> {
private static final Logger _log = Logger.getLogger(Entry.class);
protected long _minScn = 0;
protected long _maxScn = 0;
protected final EntryValueFactory<T> _valFactory;
protected int _entryCapacity;
private File _entryFile = null;
/**
* Create a new entry to hold updates to an array.
*
* @param valFactory
* The factory for manufacturing EntryValue(s).
* @param initialCapacity
* The initial number of values this entry can hold.
*/
protected AbstractEntry(EntryValueFactory<T> valFactory, int initialCapacity) {
this._valFactory = valFactory;
this._entryCapacity = initialCapacity;
}
/**
* Gets the Entry file.
*
* @return this Entry's file.
*/
@Override
public File getFile() {
return _entryFile;
}
/**
* Get the minimum SCN of updates maintained by this Entry.
*/
@Override
public final long getMinScn() {
return _minScn;
}
/**
* Get the maximum SCN of updates maintained by this Entry.
*/
@Override
public final long getMaxScn() {
return _maxScn;
}
@Override
public final EntryValueFactory<T> getValueFactory() {
return _valFactory;
}
@Override
public final int capacity() {
return _entryCapacity;
}
@Override
public final boolean isFull() {
return size() >= _entryCapacity;
}
@Override
public final boolean isEmpty() {
return size() == 0;
}
@Override
public void clear() {
_minScn = 0;
_maxScn = 0;
}
@Override
public int compareTo(Entry<T> e) {
return (_maxScn < e.getMaxScn() ? -1 : (_maxScn == e.getMaxScn() ? (_minScn < e.getMinScn() ? -1 : (_minScn == e.getMinScn() ? 0 : 1)) : 1));
}
/**
* Saves to a file.
*
* @param file
* @throws IOException
*/
public final void save(File file) throws IOException {
_entryFile = file;
Chronos c = new Chronos();
DataWriter out = new FastDataWriter(file);
try {
out.open();
// Save entry head
out.writeLong(STORAGE_VERSION); // write the entry file version
out.writeLong(_minScn);
out.writeLong(_maxScn);
out.writeInt(size());
// Save entry body
saveDataSection(out);
// Save entry tail.
out.writeLong(_minScn);
out.writeLong(_maxScn);
} finally {
out.close();
}
if(_log.isInfoEnabled()) {
_log.info("Saved entry: minScn=" + _minScn + " maxScn=" + _maxScn + " size=" + size() + " file=" + file.getName() + " in " + c.getElapsedTime());
}
}
/**
* Loads an entry from a given file.
*
* @param file
* @throws IOException
*/
public void load(File file) throws IOException {
_entryFile = file;
Chronos c = new Chronos();
ChannelReader in = new ChannelReader(file);
try {
in.open();
// Read entry head
long fileVersion = in.readLong();
if (fileVersion != STORAGE_VERSION) {
throw new RuntimeException("Wrong storage version " + fileVersion + " encounted in " + file.getAbsolutePath() + ". Version " + STORAGE_VERSION
+ " expected.");
}
long minScnHead = in.readLong();
long maxScnHead = in.readLong();
int length = in.readInt();
// Read entry body
loadDataSection(in, length);
// Read entry tail
long minScnTail = in.readLong();
long maxScnTail = in.readLong();
if (minScnHead != minScnTail) {
throw new IOException("min scns don't match: " + minScnHead + " vs " + minScnTail);
}
if (maxScnHead != maxScnTail) {
throw new IOException("max scns don't match:" + maxScnHead + " vs " + maxScnTail);
}
_minScn = minScnHead;
_maxScn = maxScnHead;
if(_log.isInfoEnabled()) {
_log.info("loaded entry: minScn=" + _minScn + " maxScn=" + _maxScn + " size=" + size() + " file=" + file.getName() + " in " + c.getElapsedTime());
}
} finally {
in.close();
}
}
abstract protected void saveDataSection(DataWriter out) throws IOException;
abstract protected void loadDataSection(DataReader in, int cnt) throws IOException;
protected final void maintainScn(long scn) {
_maxScn = Math.max(_maxScn, scn);
_minScn = (_minScn == 0) ? scn : Math.min(_minScn, scn);
}
}