package org.apache.lucene.index;
/**
* Copyright 2004 The Apache Software Foundation
*
* 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.
*/
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.InputStream;
import org.apache.lucene.store.OutputStream;
import org.apache.lucene.store.Lock;
import java.util.HashMap;
import java.io.IOException;
/**
* 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.
*
* @author Dmitry Serebrennikov
* @version $Id: CompoundFileReader.java,v 1.7 2004/07/12 14:36:04 otis Exp $
*/
class CompoundFileReader extends Directory {
private static final class FileEntry {
long offset;
long length;
}
// Base info
private Directory directory;
private String fileName;
// Reference count
private boolean open;
private InputStream stream;
private HashMap entries = new HashMap();
public CompoundFileReader(Directory dir, String name)
throws IOException
{
directory = dir;
fileName = name;
boolean success = false;
try {
stream = dir.openFile(name);
// read the directory and init files
int count = stream.readVInt();
FileEntry entry = null;
for (int i=0; i<count; i++) {
long offset = stream.readLong();
String id = stream.readString();
if (entry != null) {
// set length of the previous entry
entry.length = offset - entry.offset;
}
entry = new FileEntry();
entry.offset = offset;
entries.put(id, entry);
}
// set the length of the final entry
if (entry != null) {
entry.length = stream.length() - entry.offset;
}
success = true;
} finally {
if (! success && (stream != null)) {
try {
stream.close();
} catch (IOException e) { }
}
}
}
public Directory getDirectory() {
return directory;
}
public String getName() {
return fileName;
}
public synchronized void close() throws IOException {
if (stream == null)
throw new IOException("Already closed");
entries.clear();
stream.close();
stream = null;
}
public synchronized InputStream openFile(String id)
throws IOException
{
if (stream == null)
throw new IOException("Stream closed");
FileEntry entry = (FileEntry) entries.get(id);
if (entry == null)
throw new IOException("No sub-file with id " + id + " found");
return new CSInputStream(stream, entry.offset, entry.length);
}
/** Returns an array of strings, one for each file in the directory. */
public String[] list() {
String res[] = new String[entries.size()];
return (String[]) entries.keySet().toArray(res);
}
/** Returns true iff a file with the given name exists. */
public boolean fileExists(String name) {
return entries.containsKey(name);
}
/** Returns the time the named file was last modified. */
public long fileModified(String name) throws IOException {
return directory.fileModified(fileName);
}
/** Set the modified time of an existing file to now. */
public void touchFile(String name) throws IOException {
directory.touchFile(fileName);
}
/** Removes an existing file in the directory. */
public void deleteFile(String name)
{
throw new UnsupportedOperationException();
}
/** Renames an existing file in the directory.
If a file already exists with the new name, then it is replaced.
This replacement should be atomic. */
public void renameFile(String from, String to)
{
throw new UnsupportedOperationException();
}
/** Returns the length of a file in the directory. */
public long fileLength(String name)
throws IOException
{
FileEntry e = (FileEntry) entries.get(name);
if (e == null)
throw new IOException("File " + name + " does not exist");
return e.length;
}
/** Creates a new, empty file in the directory with the given name.
Returns a stream writing this file. */
public OutputStream createFile(String name)
{
throw new UnsupportedOperationException();
}
/** Construct a {@link Lock}.
* @param name the name of the lock file
*/
public Lock makeLock(String name)
{
throw new UnsupportedOperationException();
}
/** Implementation of an InputStream that reads from a portion of the
* compound file. The visibility is left as "package" *only* because
* this helps with testing since JUnit test cases in a different class
* can then access package fields of this class.
*/
static final class CSInputStream extends InputStream {
InputStream base;
long fileOffset;
CSInputStream(final InputStream base, final long fileOffset, final long length)
throws IOException
{
this.base = base;
this.fileOffset = fileOffset;
this.length = length; // variable in the superclass
}
/** Expert: implements buffer refill. Reads bytes from the current
* position in the input.
* @param b the array to read bytes into
* @param offset the offset in the array to start storing bytes
* @param length the number of bytes to read
*/
protected void readInternal(byte[] b, int offset, int len)
throws IOException
{
synchronized (base) {
long start = getFilePointer();
if(start + len > length)
throw new IOException("read past EOF");
base.seek(fileOffset + start);
base.readBytes(b, offset, len);
}
}
/** Expert: implements seek. Sets current position in this file, where
* the next {@link #readInternal(byte[],int,int)} will occur.
* @see #readInternal(byte[],int,int)
*/
protected void seekInternal(long pos) throws IOException {}
/** Closes the stream to futher operations. */
public void close() throws IOException {}
}
}
|
