/*
* Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.store.fs;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import org.h2.compress.CompressLZF;
import org.h2.constant.ErrorCode;
import org.h2.message.DbException;
import org.h2.util.MathUtils;
import org.h2.util.New;
/**
* This file system keeps files fully in memory. There is an option to compress
* file blocks to safe memory.
*/
public class FilePathMem extends FilePath {
private static final TreeMap<String, FileMemData> MEMORY_FILES = new TreeMap<String, FileMemData>();
public FilePathMem getPath(String path) {
FilePathMem p = new FilePathMem();
p.name = getCanonicalPath(path);
return p;
}
public long size() {
return getMemoryFile().length();
}
public void moveTo(FilePath newName) {
synchronized (MEMORY_FILES) {
FileMemData f = getMemoryFile();
f.setName(newName.name);
MEMORY_FILES.remove(name);
MEMORY_FILES.put(newName.name, f);
}
}
public boolean createFile() {
synchronized (MEMORY_FILES) {
if (exists()) {
return false;
}
getMemoryFile();
}
return true;
}
public boolean exists() {
if (isRoot()) {
return true;
}
synchronized (MEMORY_FILES) {
return MEMORY_FILES.get(name) != null;
}
}
public void delete() {
if (isRoot()) {
return;
}
synchronized (MEMORY_FILES) {
MEMORY_FILES.remove(name);
}
}
public List<FilePath> newDirectoryStream() {
ArrayList<FilePath> list = New.arrayList();
synchronized (MEMORY_FILES) {
for (String n : MEMORY_FILES.tailMap(name).keySet()) {
if (n.startsWith(name)) {
list.add(getPath(n));
} else {
break;
}
}
return list;
}
}
public boolean setReadOnly() {
return getMemoryFile().setReadOnly();
}
public boolean canWrite() {
return getMemoryFile().canWrite();
}
public FilePathMem getParent() {
int idx = name.lastIndexOf('/');
return idx < 0 ? null : getPath(name.substring(0, idx));
}
public boolean isDirectory() {
if (isRoot()) {
return true;
}
// TODO in memory file system currently
// does not really support directories
synchronized (MEMORY_FILES) {
return MEMORY_FILES.get(name) == null;
}
}
public boolean isAbsolute() {
// TODO relative files are not supported
return true;
}
public FilePathMem toRealPath() {
return this;
}
public long lastModified() {
return getMemoryFile().getLastModified();
}
public void createDirectory() {
if (exists() && isDirectory()) {
throw DbException.get(ErrorCode.FILE_CREATION_FAILED_1, name + " (a file with this name already exists)");
}
// TODO directories are not really supported
}
public OutputStream newOutputStream(boolean append) {
try {
FileMemData obj = getMemoryFile();
FileMem m = new FileMem(obj, false);
return new FileChannelOutputStream(m, append);
} catch (IOException e) {
throw DbException.convertIOException(e, name);
}
}
public InputStream newInputStream() {
FileMemData obj = getMemoryFile();
FileMem m = new FileMem(obj, true);
return new FileChannelInputStream(m);
}
public FileChannel open(String mode) {
FileMemData obj = getMemoryFile();
return new FileMem(obj, "r".equals(mode));
}
private FileMemData getMemoryFile() {
synchronized (MEMORY_FILES) {
FileMemData m = MEMORY_FILES.get(name);
if (m == null) {
m = new FileMemData(name, compressed());
MEMORY_FILES.put(name, m);
}
return m;
}
}
private boolean isRoot() {
return name.equals(getScheme());
}
private static String getCanonicalPath(String fileName) {
fileName = fileName.replace('\\', '/');
int idx = fileName.indexOf(':') + 1;
if (fileName.length() > idx && fileName.charAt(idx) != '/') {
fileName = fileName.substring(0, idx) + "/" + fileName.substring(idx);
}
return fileName;
}
public String getScheme() {
return "memFS";
}
/**
* Whether the file should be compressed.
*
* @return if it should be compressed.
*/
boolean compressed() {
return false;
}
}
/**
* A memory file system that compresses blocks to conserve memory.
*/
class FilePathMemLZF extends FilePathMem {
boolean compressed() {
return true;
}
public String getScheme() {
return "memLZF";
}
}
/**
* This class represents an in-memory file.
*/
class FileMem extends FileBase {
private final FileMemData data;
private final boolean readOnly;
private long pos;
FileMem(FileMemData data, boolean readOnly) {
this.data = data;
this.readOnly = readOnly;
}
public long size() {
return data.length();
}
public FileChannel truncate(long newLength) throws IOException {
if (newLength < size()) {
data.touch(readOnly);
pos = Math.min(pos, newLength);
data.truncate(newLength);
}
return this;
}
public FileChannel position(long newPos) {
this.pos = (int) newPos;
return this;
}
public int write(ByteBuffer src) throws IOException {
int len = src.remaining();
if (len == 0) {
return 0;
}
data.touch(readOnly);
pos = data.readWrite(pos, src.array(), src.position(), len, true);
src.position(src.position() + len);
return len;
}
public int read(ByteBuffer dst) throws IOException {
int len = dst.remaining();
if (len == 0) {
return 0;
}
long newPos = data.readWrite(pos, dst.array(), dst.position(), len, false);
len = (int) (newPos - pos);
if (len <= 0) {
return -1;
}
dst.position(dst.position() + len);
pos = newPos;
return len;
}
public long position() {
return pos;
}
public void implCloseChannel() throws IOException {
pos = 0;
}
public void force(boolean metaData) throws IOException {
// do nothing
}
public synchronized FileLock tryLock(long position, long size, boolean shared) throws IOException {
return null;
}
public String toString() {
return data.getName();
}
}
/**
* This class contains the data of an in-memory random access file.
* Data compression using the LZF algorithm is supported as well.
*/
class FileMemData {
private static final int CACHE_SIZE = 8;
private static final int BLOCK_SIZE_SHIFT = 10;
private static final int BLOCK_SIZE = 1 << BLOCK_SIZE_SHIFT;
private static final int BLOCK_SIZE_MASK = BLOCK_SIZE - 1;
private static final CompressLZF LZF = new CompressLZF();
private static final byte[] BUFFER = new byte[BLOCK_SIZE * 2];
private static final byte[] COMPRESSED_EMPTY_BLOCK;
private static final Cache<CompressItem, CompressItem> COMPRESS_LATER =
new Cache<CompressItem, CompressItem>(CACHE_SIZE);
private String name;
private final boolean compress;
private long length;
private byte[][] data;
private long lastModified;
private boolean isReadOnly;
static {
byte[] n = new byte[BLOCK_SIZE];
int len = LZF.compress(n, BLOCK_SIZE, BUFFER, 0);
COMPRESSED_EMPTY_BLOCK = new byte[len];
System.arraycopy(BUFFER, 0, COMPRESSED_EMPTY_BLOCK, 0, len);
}
/**
* This small cache compresses the data if an element leaves the cache.
*/
static class Cache<K, V> extends LinkedHashMap<K, V> {
private static final long serialVersionUID = 1L;
private int size;
Cache(int size) {
super(size, (float) 0.75, true);
this.size = size;
}
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
if (size() < size) {
return false;
}
CompressItem c = (CompressItem) eldest.getKey();
compress(c.data, c.page);
return true;
}
}
/**
* Represents a compressed item.
*/
static class CompressItem {
/**
* The file data.
*/
byte[][] data;
/**
* The page to compress.
*/
int page;
public int hashCode() {
return page;
}
public boolean equals(Object o) {
if (o instanceof CompressItem) {
CompressItem c = (CompressItem) o;
return c.data == data && c.page == page;
}
return false;
}
}
FileMemData(String name, boolean compress) {
this.name = name;
this.compress = compress;
data = new byte[0][];
lastModified = System.currentTimeMillis();
}
private static void compressLater(byte[][] data, int page) {
CompressItem c = new CompressItem();
c.data = data;
c.page = page;
synchronized (LZF) {
COMPRESS_LATER.put(c, c);
}
}
private static void expand(byte[][] data, int page) {
byte[] d = data[page];
if (d.length == BLOCK_SIZE) {
return;
}
byte[] out = new byte[BLOCK_SIZE];
if (d != COMPRESSED_EMPTY_BLOCK) {
synchronized (LZF) {
LZF.expand(d, 0, d.length, out, 0, BLOCK_SIZE);
}
}
data[page] = out;
}
/**
* Compress the data in a byte array.
*
* @param data the page array
* @param page which page to compress
*/
static void compress(byte[][] data, int page) {
byte[] d = data[page];
synchronized (LZF) {
int len = LZF.compress(d, BLOCK_SIZE, BUFFER, 0);
if (len <= BLOCK_SIZE) {
d = new byte[len];
System.arraycopy(BUFFER, 0, d, 0, len);
data[page] = d;
}
}
}
/**
* Update the last modified time.
*
* @param openReadOnly if the file was opened in read-only mode
*/
void touch(boolean openReadOnly) throws IOException {
if (isReadOnly || openReadOnly) {
throw new IOException("Read only");
}
lastModified = System.currentTimeMillis();
}
/**
* Get the file length.
*
* @return the length
*/
long length() {
return length;
}
/**
* Truncate the file.
*
* @param newLength the new length
*/
void truncate(long newLength) {
changeLength(newLength);
long end = MathUtils.roundUpLong(newLength, BLOCK_SIZE);
if (end != newLength) {
int lastPage = (int) (newLength >>> BLOCK_SIZE_SHIFT);
expand(data, lastPage);
byte[] d = data[lastPage];
for (int i = (int) (newLength & BLOCK_SIZE_MASK); i < BLOCK_SIZE; i++) {
d[i] = 0;
}
if (compress) {
compressLater(data, lastPage);
}
}
}
private void changeLength(long len) {
length = len;
len = MathUtils.roundUpLong(len, BLOCK_SIZE);
int blocks = (int) (len >>> BLOCK_SIZE_SHIFT);
if (blocks != data.length) {
byte[][] n = new byte[blocks][];
System.arraycopy(data, 0, n, 0, Math.min(data.length, n.length));
for (int i = data.length; i < blocks; i++) {
n[i] = COMPRESSED_EMPTY_BLOCK;
}
data = n;
}
}
/**
* Read or write.
*
* @param pos the position
* @param b the byte array
* @param off the offset within the byte array
* @param len the number of bytes
* @param write true for writing
* @return the new position
*/
long readWrite(long pos, byte[] b, int off, int len, boolean write) {
long end = pos + len;
if (end > length) {
if (write) {
changeLength(end);
} else {
return pos;
}
}
while (len > 0) {
int l = (int) Math.min(len, BLOCK_SIZE - (pos & BLOCK_SIZE_MASK));
int page = (int) (pos >>> BLOCK_SIZE_SHIFT);
expand(data, page);
byte[] block = data[page];
int blockOffset = (int) (pos & BLOCK_SIZE_MASK);
if (write) {
System.arraycopy(b, off, block, blockOffset, l);
} else {
System.arraycopy(block, blockOffset, b, off, l);
}
if (compress) {
compressLater(data, page);
}
off += l;
pos += l;
len -= l;
}
return pos;
}
/**
* Set the file name.
*
* @param name the name
*/
void setName(String name) {
this.name = name;
}
/**
* Get the file name
*
* @return the name
*/
String getName() {
return name;
}
/**
* Get the last modified time.
*
* @return the time
*/
long getLastModified() {
return lastModified;
}
/**
* Check whether writing is allowed.
*
* @return true if it is
*/
boolean canWrite() {
return !isReadOnly;
}
/**
* Set the read-only flag.
*
* @return true
*/
boolean setReadOnly() {
isReadOnly = true;
return true;
}
}