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TripleStore implementation for SemanticWebBuilder using LevelDB
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/**
* Copyright (C) 2011 the original author or authors.
* See the notice.md file distributed with this work for additional
* information regarding copyright ownership.
*
* 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 org.iq80.leveldb.impl;
import com.google.common.base.Charsets;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.io.Files;
import java.io.File;
import java.io.IOException;
import java.util.List;
public class Filename
{
public enum FileType
{
LOG,
DB_LOCK,
TABLE,
DESCRIPTOR,
CURRENT,
TEMP,
INFO_LOG // Either the current one, or an old one
}
/**
* Return the name of the log file with the specified number.
*/
public static String logFileName(long number)
{
return makeFileName(number, "log");
}
/**
* Return the name of the sstable with the specified number.
*/
public static String tableFileName(long number)
{
return makeFileName(number, "sst");
}
/**
* Return the name of the descriptor file with the specified incarnation number.
*/
public static String descriptorFileName(long number)
{
Preconditions.checkArgument(number >= 0, "number is negative");
return String.format("MANIFEST-%06d", number);
}
/**
* Return the name of the current file.
*/
public static String currentFileName()
{
return "CURRENT";
}
/**
* Return the name of the lock file.
*/
public static String lockFileName()
{
return "LOCK";
}
/**
* Return the name of a temporary file with the specified number.
*/
public static String tempFileName(long number)
{
return makeFileName(number, "dbtmp");
}
/**
* Return the name of the info log file.
*/
public static String infoLogFileName()
{
return "LOG";
}
/**
* Return the name of the old info log file.
*/
public static String oldInfoLogFileName()
{
return "LOG.old";
}
/**
* If filename is a leveldb file, store the type of the file in *type.
* The number encoded in the filename is stored in *number. If the
* filename was successfully parsed, returns true. Else return false.
*/
public static FileInfo parseFileName(File file)
{
// Owned filenames have the form:
// dbname/CURRENT
// dbname/LOCK
// dbname/LOG
// dbname/LOG.old
// dbname/MANIFEST-[0-9]+
// dbname/[0-9]+.(log|sst|dbtmp)
String fileName = file.getName();
if ("CURRENT".equals(fileName)) {
return new FileInfo(FileType.CURRENT);
}
else if ("LOCK".equals(fileName)) {
return new FileInfo(FileType.DB_LOCK);
}
else if ("LOG".equals(fileName)) {
return new FileInfo(FileType.INFO_LOG);
}
else if ("LOG.old".equals(fileName)) {
return new FileInfo(FileType.INFO_LOG);
}
else if (fileName.startsWith("MANIFEST-")) {
long fileNumber = Long.parseLong(removePrefix(fileName, "MANIFEST-"));
return new FileInfo(FileType.DESCRIPTOR, fileNumber);
}
else if (fileName.endsWith(".log")) {
long fileNumber = Long.parseLong(removeSuffix(fileName, ".log"));
return new FileInfo(FileType.LOG, fileNumber);
}
else if (fileName.endsWith(".sst")) {
long fileNumber = Long.parseLong(removeSuffix(fileName, ".sst"));
return new FileInfo(FileType.TABLE, fileNumber);
}
else if (fileName.endsWith(".dbtmp")) {
long fileNumber = Long.parseLong(removeSuffix(fileName, ".dbtmp"));
return new FileInfo(FileType.TEMP, fileNumber);
}
return null;
}
/**
* Make the CURRENT file point to the descriptor file with the
* specified number.
* @return true if successful; false otherwise
*/
public static boolean setCurrentFile(File databaseDir, long descriptorNumber)
throws IOException
{
String manifest = descriptorFileName(descriptorNumber);
String temp = tempFileName(descriptorNumber);
File tempFile = new File(databaseDir, temp);
Files.write(manifest + "\n", tempFile, Charsets.UTF_8);
File to = new File(databaseDir, currentFileName());
boolean ok = tempFile.renameTo(to);
if (!ok) {
tempFile.delete();
Files.write(manifest + "\n", to, Charsets.UTF_8);
}
return ok;
}
public static List listFiles(File dir)
{
File[] files = dir.listFiles();
if (files == null) {
return ImmutableList.of();
}
return ImmutableList.copyOf(files);
}
private static String makeFileName(long number, String suffix)
{
Preconditions.checkArgument(number >= 0, "number is negative");
Preconditions.checkNotNull(suffix, "suffix is null");
return String.format("%06d.%s", number, suffix);
}
private static String removePrefix(String value, String prefix)
{
return value.substring(prefix.length());
}
private static String removeSuffix(String value, String suffix)
{
return value.substring(0, value.length() - suffix.length());
}
public static class FileInfo
{
private FileType fileType;
private long fileNumber;
public FileInfo(FileType fileType)
{
this(fileType, 0);
}
public FileInfo(FileType fileType, long fileNumber)
{
Preconditions.checkNotNull(fileType, "fileType is null");
this.fileType = fileType;
this.fileNumber = fileNumber;
}
public FileType getFileType()
{
return fileType;
}
public long getFileNumber()
{
return fileNumber;
}
@Override
public boolean equals(Object o)
{
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
FileInfo fileInfo = (FileInfo) o;
if (fileNumber != fileInfo.fileNumber) {
return false;
}
if (fileType != fileInfo.fileType) {
return false;
}
return true;
}
@Override
public int hashCode()
{
int result = fileType.hashCode();
result = 31 * result + (int) (fileNumber ^ (fileNumber >>> 32));
return result;
}
@Override
public String toString()
{
final StringBuilder sb = new StringBuilder();
sb.append("FileInfo");
sb.append("{fileType=").append(fileType);
sb.append(", fileNumber=").append(fileNumber);
sb.append('}');
return sb.toString();
}
}
}