/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
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* or http://forgerock.org/license/CDDLv1.0.html.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at legal-notices/CDDLv1_0.txt.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information:
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* Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*
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*
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* Copyright 2014 ForgeRock AS.
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*/
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package org.opends.server.replication.server.changelog.file;
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import static org.opends.server.loggers.debug.DebugLogger.*;
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import java.io.BufferedOutputStream;
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import java.io.File;
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import java.io.FileDescriptor;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.io.SyncFailedException;
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import java.util.HashMap;
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import java.util.Map;
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import org.opends.server.replication.server.changelog.api.ChangelogException;
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import org.opends.server.types.ByteString;
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import org.opends.server.util.StaticUtils;
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import static org.opends.messages.ReplicationMessages.*;
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/**
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* A writer on a log file.
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* <p>
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* The writer is cached in order to have a single writer per file in the JVM.
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*/
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class LogWriter extends OutputStream
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{
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/** The cache of log writers. There is a single writer per file in the JVM. */
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private static final Map<File, LogWriter> logWritersCache = new HashMap<File, LogWriter>();
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/** The exclusive lock used to acquire or close a log writer. */
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private static final Object lock = new Object();
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/** The file to write in. */
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private final File file;
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/** The stream to write data in the file. */
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private final BufferedOutputStream stream;
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/** The file descriptor on the file. */
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private final FileDescriptor fileDescriptor;
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/** The number of references on this writer. */
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private int referenceCount;
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/**
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* Creates a writer on the provided file.
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*
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* @param file
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* The file to write.
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* @param stream
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* The stream to write in the file.
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* @param fileDescriptor
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* The descriptor on the file.
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*/
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private LogWriter(final File file, BufferedOutputStream stream, FileDescriptor fileDescriptor)
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throws ChangelogException
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{
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this.file = file;
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this.stream = stream;
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this.fileDescriptor = fileDescriptor;
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this.referenceCount = 1;
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}
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/**
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* Returns a log writer on the provided file, creating it if necessary.
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*
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* @param file
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* The log file to write in.
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* @return the log writer
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* @throws ChangelogException
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* If a problem occurs.
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*/
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public static LogWriter acquireWriter(File file) throws ChangelogException
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{
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synchronized (lock)
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{
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LogWriter logWriter = logWritersCache.get(file);
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if (logWriter == null)
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{
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try
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{
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final FileOutputStream stream = new FileOutputStream(file, true);
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logWriter = new LogWriter(file, new BufferedOutputStream(stream), stream.getFD());
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}
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catch (Exception e)
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{
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throw new ChangelogException(ERR_CHANGELOG_UNABLE_TO_OPEN_LOG_FILE.get(file.getPath()));
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}
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logWritersCache.put(file, logWriter);
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}
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else
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{
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logWriter.incrementRefCounter();
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}
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return logWriter;
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}
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}
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/** {@inheritDoc} */
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@Override
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public void write(int b) throws IOException
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{
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stream.write(b);
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}
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/** {@inheritDoc} */
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@Override
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public void write(byte[] b) throws IOException
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{
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stream.write(b);
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}
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/** {@inheritDoc} */
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@Override
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public void write(byte[] b, int off, int len) throws IOException
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{
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stream.write(b, off, len);
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}
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/**
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* Writes the provided byte string to the underlying output stream of this writer.
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*
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* @param bs
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* The byte string to write.
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* @throws IOException
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* if an I/O error occurs. In particular, an IOException may be
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* thrown if the output stream has been closed.
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*/
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public void write(ByteString bs) throws IOException
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{
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bs.copyTo(stream);
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}
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/** {@inheritDoc} */
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@Override
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public void flush() throws IOException
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{
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stream.flush();
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}
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/**
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* Synchronize all modifications to the file to the underlying device.
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*
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* @throws SyncFailedException
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* If synchronization fails.
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*/
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void sync() throws SyncFailedException {
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fileDescriptor.sync();
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}
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/** {@inheritDoc} */
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@Override
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public void close()
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{
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synchronized (lock)
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{
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LogWriter writer = logWritersCache.get(file);
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if (writer == null)
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{
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// writer is already closed
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return;
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}
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// counter == 0 should never happen
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if (referenceCount == 0 || referenceCount == 1)
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{
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StaticUtils.close(stream);
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logWritersCache.remove(file);
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referenceCount = 0;
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}
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else
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{
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referenceCount--;
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}
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}
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}
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private void incrementRefCounter()
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{
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referenceCount++;
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}
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}
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