/*
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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 com.forgerock.opendj.util.Validator.*;
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import static org.opends.messages.ReplicationMessages.*;
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import static org.opends.server.replication.server.changelog.file.BlockLogReader.*;
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import java.io.Closeable;
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import java.io.IOException;
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import java.io.SyncFailedException;
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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.types.ByteStringBuilder;
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/**
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* A log writer, using fixed-size blocks to allow fast retrieval when reading.
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* <p>
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* The log file contains record offsets at fixed block size : given block size N,
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* an offset is written at every N bytes. The offset contains the number of bytes to
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* reach the beginning of previous record (or next record if offset equals 0).
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*
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* @param <K>
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* Type of the key of a record, which must be comparable.
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* @param <V>
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* Type of the value of a record.
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*/
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class BlockLogWriter<K extends Comparable<K>, V> implements Closeable
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{
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private final int blockSize;
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private final RecordParser<K, V> parser;
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private final LogWriter writer;
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/**
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* Creates a writer for the provided log writer and parser.
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*
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* @param <K>
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* Type of the key of a record, which must be comparable.
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* @param <V>
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* Type of the value of a record.
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* @param writer
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* The writer on the log file.
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* @param parser
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* The parser to encode the records.
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* @return a new log reader
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*/
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static <K extends Comparable<K>, V> BlockLogWriter<K,V> newWriter(
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final LogWriter writer, final RecordParser<K, V> parser)
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{
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return new BlockLogWriter<K, V>(writer, parser, BLOCK_SIZE);
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}
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/**
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* Creates a writer for the provided log writer, parser and size for blocks.
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* <p>
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* This method is intended for tests only, to allow tuning of the block size.
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*
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* @param <K>
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* Type of the key of a record, which must be comparable.
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* @param <V>
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* Type of the value of a record.
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* @param writer
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* The writer on the log file.
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* @param parser
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* The parser to encode the records.
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* @param blockSize
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* The size of each block, or frequency at which the record offset is
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* present in the log file.
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* @return a new log reader
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*/
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static <K extends Comparable<K>, V> BlockLogWriter<K,V> newWriterForTests(
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final LogWriter writer, final RecordParser<K, V> parser, final int blockSize)
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{
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return new BlockLogWriter<K, V>(writer, parser, blockSize);
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}
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/**
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* Creates the writer with an underlying writer, a parser and a size for blocks.
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*
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* @param writer
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* The writer to the log file.
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* @param parser
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* The parser to encode the records.
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* @param blockSize
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* The size of each block.
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*/
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private BlockLogWriter(LogWriter writer, RecordParser<K, V> parser, int blockSize)
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{
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ensureNotNull(writer, parser);
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this.writer = writer;
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this.parser = parser;
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this.blockSize = blockSize;
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}
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/**
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* Writes the provided record to the log file.
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*
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* @param record
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* The record to write.
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* @throws ChangelogException
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* If a problem occurs during write.
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*/
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public void write(final Record<K, V> record) throws ChangelogException
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{
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try
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{
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write(parser.encodeRecord(record));
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writer.flush();
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}
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catch (IOException e)
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{
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throw new ChangelogException(ERR_CHANGELOG_UNABLE_TO_ADD_RECORD.get(record.toString(),
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writer.getFile().getPath()), e);
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}
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}
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/**
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* Returns the number of bytes written in the log file.
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*
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* @return the number of bytes
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*/
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public long getBytesWritten()
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{
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return writer.getBytesWritten();
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}
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/**
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* Synchronize all modifications to the log 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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public void sync() throws SyncFailedException
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{
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writer.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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writer.close();
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}
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/**
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* Writes the provided byte string to the log file.
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*
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* @param record
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* The value to write.
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* @throws IOException
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* If an error occurs while writing
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*/
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private void write(final ByteString record) throws IOException
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{
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// Add length of record before writing
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ByteString data = new ByteStringBuilder(SIZE_OF_RECORD_SIZE + record.length()).
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append(record.length()).
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append(record).
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toByteString();
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int distanceToBlockStart = BlockLogReader.getDistanceToNextBlockStart(writer.getBytesWritten(), blockSize);
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int cumulatedDistanceToBeginning = distanceToBlockStart;
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int dataPosition = 0;
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int dataRemaining = data.length();
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final int dataSizeForOneBlock = blockSize - SIZE_OF_BLOCK_OFFSET;
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while (distanceToBlockStart < dataRemaining)
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{
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if (distanceToBlockStart > 0)
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{
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// append part of record
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final int dataEndPosition = dataPosition + distanceToBlockStart;
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writer.write(data.subSequence(dataPosition, dataEndPosition));
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dataPosition = dataEndPosition;
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dataRemaining -= distanceToBlockStart;
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}
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// append the offset to the record
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writer.write(ByteString.valueOf(cumulatedDistanceToBeginning));
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// next step
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distanceToBlockStart = dataSizeForOneBlock;
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cumulatedDistanceToBeginning += blockSize;
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}
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// append the remaining bytes to finish the record
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writer.write(data.subSequence(dataPosition, data.length()));
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}
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}
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