/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.mvstore;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.nio.channels.OverlappingFileLockException;
import org.h2.mvstore.cache.FilePathCache;
import org.h2.store.fs.FilePath;
import org.h2.store.fs.FilePathDisk;
import org.h2.store.fs.FilePathEncrypt;
import org.h2.store.fs.FilePathNio;
/**
* The default storage mechanism of the MVStore. This implementation persists
* data to a file. The file store is responsible to persist data and for free
* space management.
*/
public class FileStore {
/**
* The number of read operations.
*/
protected long readCount;
/**
* The number of read bytes.
*/
protected long readBytes;
/**
* The number of write operations.
*/
protected long writeCount;
/**
* The number of written bytes.
*/
protected long writeBytes;
/**
* The free spaces between the chunks. The first block to use is block 2
* (the first two blocks are the store header).
*/
protected final FreeSpaceBitSet freeSpace =
new FreeSpaceBitSet(2, MVStore.BLOCK_SIZE);
/**
* The file name.
*/
protected String fileName;
/**
* Whether this store is read-only.
*/
protected boolean readOnly;
/**
* The file size (cached).
*/
protected long fileSize;
/**
* The file.
*/
protected FileChannel file;
/**
* The encrypted file (if encryption is used).
*/
protected FileChannel encryptedFile;
/**
* The file lock.
*/
protected FileLock fileLock;
@Override
public String toString() {
return fileName;
}
/**
* Read from the file.
*
* @param pos the write position
* @param len the number of bytes to read
* @return the byte buffer
*/
public ByteBuffer readFully(long pos, int len) {
ByteBuffer dst = ByteBuffer.allocate(len);
DataUtils.readFully(file, pos, dst);
readCount++;
readBytes += len;
return dst;
}
/**
* Write to the file.
*
* @param pos the write position
* @param src the source buffer
*/
public void writeFully(long pos, ByteBuffer src) {
int len = src.remaining();
fileSize = Math.max(fileSize, pos + len);
DataUtils.writeFully(file, pos, src);
writeCount++;
writeBytes += len;
}
/**
* Try to open the file.
*
* @param fileName the file name
* @param readOnly whether the file should only be opened in read-only mode,
* even if the file is writable
* @param encryptionKey the encryption key, or null if encryption is not
* used
*/
public void open(String fileName, boolean readOnly, char[] encryptionKey) {
if (file != null) {
return;
}
if (fileName != null) {
// ensure the Cache file system is registered
FilePathCache.INSTANCE.getScheme();
FilePath p = FilePath.get(fileName);
// if no explicit scheme was specified, NIO is used
if (p instanceof FilePathDisk &&
!fileName.startsWith(p.getScheme() + ":")) {
// ensure the NIO file system is registered
FilePathNio.class.getName();
fileName = "nio:" + fileName;
}
}
this.fileName = fileName;
FilePath f = FilePath.get(fileName);
FilePath parent = f.getParent();
if (parent != null && !parent.exists()) {
throw DataUtils.newIllegalArgumentException(
"Directory does not exist: {0}", parent);
}
if (f.exists() && !f.canWrite()) {
readOnly = true;
}
this.readOnly = readOnly;
try {
file = f.open(readOnly ? "r" : "rw");
if (encryptionKey != null) {
byte[] key = FilePathEncrypt.getPasswordBytes(encryptionKey);
encryptedFile = file;
file = new FilePathEncrypt.FileEncrypt(fileName, key, file);
}
try {
if (readOnly) {
fileLock = file.tryLock(0, Long.MAX_VALUE, true);
} else {
fileLock = file.tryLock();
}
} catch (OverlappingFileLockException e) {
throw DataUtils.newIllegalStateException(
DataUtils.ERROR_FILE_LOCKED,
"The file is locked: {0}", fileName, e);
}
if (fileLock == null) {
throw DataUtils.newIllegalStateException(
DataUtils.ERROR_FILE_LOCKED,
"The file is locked: {0}", fileName);
}
fileSize = file.size();
} catch (IOException e) {
throw DataUtils.newIllegalStateException(
DataUtils.ERROR_READING_FAILED,
"Could not open file {0}", fileName, e);
}
}
/**
* Close this store.
*/
public void close() {
try {
if (fileLock != null) {
fileLock.release();
fileLock = null;
}
file.close();
freeSpace.clear();
} catch (Exception e) {
throw DataUtils.newIllegalStateException(
DataUtils.ERROR_WRITING_FAILED,
"Closing failed for file {0}", fileName, e);
} finally {
file = null;
}
}
/**
* Flush all changes.
*/
public void sync() {
try {
file.force(true);
} catch (IOException e) {
throw DataUtils.newIllegalStateException(
DataUtils.ERROR_WRITING_FAILED,
"Could not sync file {0}", fileName, e);
}
}
/**
* Get the file size.
*
* @return the file size
*/
public long size() {
return fileSize;
}
/**
* Truncate the file.
*
* @param size the new file size
*/
public void truncate(long size) {
try {
writeCount++;
file.truncate(size);
fileSize = Math.min(fileSize, size);
} catch (IOException e) {
throw DataUtils.newIllegalStateException(
DataUtils.ERROR_WRITING_FAILED,
"Could not truncate file {0} to size {1}",
fileName, size, e);
}
}
/**
* Get the file instance in use.
* <p>
* The application may read from the file (for example for online backup),
* but not write to it or truncate it.
*
* @return the file
*/
public FileChannel getFile() {
return file;
}
/**
* Get the encrypted file instance, if encryption is used.
* <p>
* The application may read from the file (for example for online backup),
* but not write to it or truncate it.
*
* @return the encrypted file, or null if encryption is not used
*/
public FileChannel getEncryptedFile() {
return encryptedFile;
}
/**
* Get the number of write operations since this store was opened.
* For file based stores, this is the number of file write operations.
*
* @return the number of write operations
*/
public long getWriteCount() {
return writeCount;
}
/**
* Get the number of written bytes since this store was opened.
*
* @return the number of write operations
*/
public long getWriteBytes() {
return writeBytes;
}
/**
* Get the number of read operations since this store was opened.
* For file based stores, this is the number of file read operations.
*
* @return the number of read operations
*/
public long getReadCount() {
return readCount;
}
/**
* Get the number of read bytes since this store was opened.
*
* @return the number of write operations
*/
public long getReadBytes() {
return readBytes;
}
public boolean isReadOnly() {
return readOnly;
}
/**
* Get the default retention time for this store in milliseconds.
*
* @return the retention time
*/
public int getDefaultRetentionTime() {
return 45000;
}
/**
* Mark the space as in use.
*
* @param pos the position in bytes
* @param length the number of bytes
*/
public void markUsed(long pos, int length) {
freeSpace.markUsed(pos, length);
}
/**
* Allocate a number of blocks and mark them as used.
*
* @param length the number of bytes to allocate
* @return the start position in bytes
*/
public long allocate(int length) {
return freeSpace.allocate(length);
}
/**
* Mark the space as free.
*
* @param pos the position in bytes
* @param length the number of bytes
*/
public void free(long pos, int length) {
freeSpace.free(pos, length);
}
public int getFillRate() {
return freeSpace.getFillRate();
}
long getFirstFree() {
return freeSpace.getFirstFree();
}
/**
* Mark the file as empty.
*/
public void clear() {
freeSpace.clear();
}
/**
* Get the file name.
*
* @return the file name
*/
public String getFileName() {
return fileName;
}
}