/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
* or http://forgerock.org/license/CDDLv1.0.html.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at legal-notices/CDDLv1_0.txt.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information:
* Portions Copyright [yyyy] [name of copyright owner]
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* CDDL HEADER END
*
*
* Copyright 2014-2015 ForgeRock AS.
*/
package org.opends.server.replication.server.changelog.file;
import static org.opends.messages.ReplicationMessages.*;
import static org.opends.server.replication.server.changelog.file.BlockLogReader.*;
import java.io.Closeable;
import java.io.IOException;
import java.io.SyncFailedException;
import org.forgerock.opendj.ldap.ByteString;
import org.forgerock.opendj.ldap.ByteStringBuilder;
import org.forgerock.util.Reject;
import org.opends.server.replication.server.changelog.api.ChangelogException;
/**
* A log writer, using fixed-size blocks to allow fast retrieval when reading.
* <p>
* The log file contains record offsets at fixed block size : given block size N,
* an offset is written at every N bytes. The offset contains the number of bytes to
* reach the beginning of previous record (or next record if offset equals 0).
*
* @param <K>
* Type of the key of a record, which must be comparable.
* @param <V>
* Type of the value of a record.
*/
class BlockLogWriter<K extends Comparable<K>, V> implements Closeable
{
private final int blockSize;
private final RecordParser<K, V> parser;
private final LogWriter writer;
/**
* Creates a writer for the provided log writer and parser.
*
* @param <K>
* Type of the key of a record, which must be comparable.
* @param <V>
* Type of the value of a record.
* @param writer
* The writer on the log file.
* @param parser
* The parser to encode the records.
* @return a new log reader
*/
static <K extends Comparable<K>, V> BlockLogWriter<K,V> newWriter(
final LogWriter writer, final RecordParser<K, V> parser)
{
return new BlockLogWriter<>(writer, parser, BLOCK_SIZE);
}
/**
* Creates a writer for the provided log writer, parser and size for blocks.
* <p>
* This method is intended for tests only, to allow tuning of the block size.
*
* @param <K>
* Type of the key of a record, which must be comparable.
* @param <V>
* Type of the value of a record.
* @param writer
* The writer on the log file.
* @param parser
* The parser to encode the records.
* @param blockSize
* The size of each block, or frequency at which the record offset is
* present in the log file.
* @return a new log reader
*/
static <K extends Comparable<K>, V> BlockLogWriter<K,V> newWriterForTests(
final LogWriter writer, final RecordParser<K, V> parser, final int blockSize)
{
return new BlockLogWriter<>(writer, parser, blockSize);
}
/**
* Creates the writer with an underlying writer, a parser and a size for blocks.
*
* @param writer
* The writer to the log file.
* @param parser
* The parser to encode the records.
* @param blockSize
* The size of each block.
*/
private BlockLogWriter(LogWriter writer, RecordParser<K, V> parser, int blockSize)
{
Reject.ifNull(writer, parser);
this.writer = writer;
this.parser = parser;
this.blockSize = blockSize;
}
/**
* Writes the provided record to the log file.
*
* @param record
* The record to write.
* @throws ChangelogException
* If a problem occurs during write.
*/
public void write(final Record<K, V> record) throws ChangelogException
{
try
{
write(parser.encodeRecord(record));
writer.flush();
}
catch (IOException e)
{
throw new ChangelogException(ERR_CHANGELOG_UNABLE_TO_ADD_RECORD.get(record.toString(),
writer.getFile().getPath()), e);
}
}
/**
* Returns the number of bytes written in the log file.
*
* @return the number of bytes
*/
public long getBytesWritten()
{
return writer.getBytesWritten();
}
/**
* Synchronize all modifications to the log file to the underlying device.
*
* @throws SyncFailedException
* If synchronization fails.
*/
public void sync() throws SyncFailedException
{
writer.sync();
}
/** {@inheritDoc} */
@Override
public void close()
{
writer.close();
}
/**
* Writes the provided byte string to the log file.
*
* @param record
* The value to write.
* @throws IOException
* If an error occurs while writing
*/
private void write(final ByteString record) throws IOException
{
// Add length of record before writing
ByteString data = new ByteStringBuilder(SIZE_OF_RECORD_SIZE + record.length()).
appendInt(record.length()).
appendBytes(record).
toByteString();
int distanceToBlockStart = BlockLogReader.getDistanceToNextBlockStart(writer.getBytesWritten(), blockSize);
int cumulatedDistanceToBeginning = distanceToBlockStart;
int dataPosition = 0;
int dataRemaining = data.length();
final int dataSizeForOneBlock = blockSize - SIZE_OF_BLOCK_OFFSET;
while (distanceToBlockStart < dataRemaining)
{
if (distanceToBlockStart > 0)
{
// append part of record
final int dataEndPosition = dataPosition + distanceToBlockStart;
writer.write(data.subSequence(dataPosition, dataEndPosition));
dataPosition = dataEndPosition;
dataRemaining -= distanceToBlockStart;
}
// append the offset to the record
writer.write(ByteString.valueOfInt(cumulatedDistanceToBeginning));
// next step
distanceToBlockStart = dataSizeForOneBlock;
cumulatedDistanceToBeginning += blockSize;
}
// append the remaining bytes to finish the record
writer.write(data.subSequence(dataPosition, data.length()));
}
}