/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.lucene.codecs.lucene50;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.apache.lucene.codecs.CodecUtil;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexFileNames;
import org.apache.lucene.index.SegmentInfo;
import org.apache.lucene.store.ChecksumIndexInput;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IOContext;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.store.IndexOutput;
import org.apache.lucene.store.Lock;
import org.apache.lucene.util.IOUtils;
/**
* Class for accessing a compound stream.
* This class implements a directory, but is limited to only read operations.
* Directory methods that would normally modify data throw an exception.
* @lucene.experimental
*/
final class Lucene50CompoundReader extends Directory {
/** Offset/Length for a slice inside of a compound file */
public static final class FileEntry {
long offset;
long length;
}
private final Directory directory;
private final String segmentName;
private final Map<String,FileEntry> entries;
private final IndexInput handle;
private int version;
/**
* Create a new CompoundFileDirectory.
*/
// TODO: we should just pre-strip "entries" and append segment name up-front like simpletext?
// this need not be a "general purpose" directory anymore (it only writes index files)
public Lucene50CompoundReader(Directory directory, SegmentInfo si, IOContext context) throws IOException {
this.directory = directory;
this.segmentName = si.name;
String dataFileName = IndexFileNames.segmentFileName(segmentName, "", Lucene50CompoundFormat.DATA_EXTENSION);
String entriesFileName = IndexFileNames.segmentFileName(segmentName, "", Lucene50CompoundFormat.ENTRIES_EXTENSION);
this.entries = readEntries(si.getId(), directory, entriesFileName);
boolean success = false;
long expectedLength = CodecUtil.indexHeaderLength(Lucene50CompoundFormat.DATA_CODEC, "");
for(Map.Entry<String,FileEntry> ent : entries.entrySet()) {
expectedLength += ent.getValue().length;
}
expectedLength += CodecUtil.footerLength();
handle = directory.openInput(dataFileName, context);
try {
CodecUtil.checkIndexHeader(handle, Lucene50CompoundFormat.DATA_CODEC, version, version, si.getId(), "");
// NOTE: data file is too costly to verify checksum against all the bytes on open,
// but for now we at least verify proper structure of the checksum footer: which looks
// for FOOTER_MAGIC + algorithmID. This is cheap and can detect some forms of corruption
// such as file truncation.
CodecUtil.retrieveChecksum(handle);
// We also validate length, because e.g. if you strip 16 bytes off the .cfs we otherwise
// would not detect it:
if (handle.length() != expectedLength) {
throw new CorruptIndexException("length should be " + expectedLength + " bytes, but is " + handle.length() + " instead", handle);
}
success = true;
} finally {
if (!success) {
IOUtils.closeWhileHandlingException(handle);
}
}
}
/** Helper method that reads CFS entries from an input stream */
private Map<String, FileEntry> readEntries(byte[] segmentID, Directory dir, String entriesFileName) throws IOException {
Map<String,FileEntry> mapping = null;
try (ChecksumIndexInput entriesStream = dir.openChecksumInput(entriesFileName, IOContext.READONCE)) {
Throwable priorE = null;
try {
version = CodecUtil.checkIndexHeader(entriesStream, Lucene50CompoundFormat.ENTRY_CODEC,
Lucene50CompoundFormat.VERSION_START,
Lucene50CompoundFormat.VERSION_CURRENT, segmentID, "");
final int numEntries = entriesStream.readVInt();
mapping = new HashMap<>(numEntries);
for (int i = 0; i < numEntries; i++) {
final FileEntry fileEntry = new FileEntry();
final String id = entriesStream.readString();
FileEntry previous = mapping.put(id, fileEntry);
if (previous != null) {
throw new CorruptIndexException("Duplicate cfs entry id=" + id + " in CFS ", entriesStream);
}
fileEntry.offset = entriesStream.readLong();
fileEntry.length = entriesStream.readLong();
}
} catch (Throwable exception) {
priorE = exception;
} finally {
CodecUtil.checkFooter(entriesStream, priorE);
}
}
return Collections.unmodifiableMap(mapping);
}
@Override
public void close() throws IOException {
IOUtils.close(handle);
}
@Override
public IndexInput openInput(String name, IOContext context) throws IOException {
ensureOpen();
final String id = IndexFileNames.stripSegmentName(name);
final FileEntry entry = entries.get(id);
if (entry == null) {
String datFileName = IndexFileNames.segmentFileName(segmentName, "", Lucene50CompoundFormat.DATA_EXTENSION);
throw new FileNotFoundException("No sub-file with id " + id + " found in compound file \"" + datFileName + "\" (fileName=" + name + " files: " + entries.keySet() + ")");
}
return handle.slice(name, entry.offset, entry.length);
}
/** Returns an array of strings, one for each file in the directory. */
@Override
public String[] listAll() {
ensureOpen();
String[] res = entries.keySet().toArray(new String[entries.size()]);
// Add the segment name
for (int i = 0; i < res.length; i++) {
res[i] = segmentName + res[i];
}
return res;
}
/** Not implemented
* @throws UnsupportedOperationException always: not supported by CFS */
@Override
public void deleteFile(String name) {
throw new UnsupportedOperationException();
}
/** Not implemented
* @throws UnsupportedOperationException always: not supported by CFS */
@Override
public void rename(String from, String to) {
throw new UnsupportedOperationException();
}
@Override
public void syncMetaData() {
}
/** Returns the length of a file in the directory.
* @throws IOException if the file does not exist */
@Override
public long fileLength(String name) throws IOException {
ensureOpen();
FileEntry e = entries.get(IndexFileNames.stripSegmentName(name));
if (e == null)
throw new FileNotFoundException(name);
return e.length;
}
@Override
public IndexOutput createOutput(String name, IOContext context) throws IOException {
throw new UnsupportedOperationException();
}
@Override
public IndexOutput createTempOutput(String prefix, String suffix, IOContext context) throws IOException {
throw new UnsupportedOperationException();
}
@Override
public void sync(Collection<String> names) {
throw new UnsupportedOperationException();
}
@Override
public Lock obtainLock(String name) {
throw new UnsupportedOperationException();
}
@Override
public String toString() {
return "CompoundFileDirectory(segment=\"" + segmentName + "\" in dir=" + directory + ")";
}
}