/*
* 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;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import org.h2.constant.ErrorCode;
import org.h2.constant.SysProperties;
import org.h2.engine.Constants;
import org.h2.message.DbException;
import org.h2.tools.CompressTool;
import org.h2.util.IOUtils;
import org.h2.util.MathUtils;
import org.h2.util.New;
import org.h2.util.StringUtils;
import org.h2.util.Utils;
import org.h2.value.Value;
import org.h2.value.ValueLob;
import org.h2.value.ValueLobDb;
/**
* This class stores LOB objects in the database.
*/
public class LobStorage {
/**
* The table id for session variables (LOBs not assigned to a table).
*/
public static final int TABLE_ID_SESSION_VARIABLE = -1;
/**
* The table id for temporary objects (not assigned to any object).
*/
public static final int TABLE_TEMP = -2;
/**
* The name of the lob data table. If this table exists, then lob storage is
* used.
*/
public static final String LOB_DATA_TABLE = "LOB_DATA";
private static final String LOB_SCHEMA = "INFORMATION_SCHEMA";
private static final String LOBS = LOB_SCHEMA + ".LOBS";
private static final String LOB_MAP = LOB_SCHEMA + ".LOB_MAP";
private static final String LOB_DATA = LOB_SCHEMA + "." + LOB_DATA_TABLE;
private static final int BLOCK_LENGTH = 20000;
/**
* The size of cache for lob block hashes. Each entry needs 2 longs (16
* bytes), therefore, the size 4096 means 64 KB.
*/
private static final int HASH_CACHE_SIZE = 4 * 1024;
private Connection conn;
private HashMap<String, PreparedStatement> prepared = New.hashMap();
private long nextBlock;
private CompressTool compress = CompressTool.getInstance();
private long[] hashBlocks = new long[HASH_CACHE_SIZE * 2];
private final DataHandler handler;
private boolean init;
public LobStorage(DataHandler handler) {
this.handler = handler;
}
/**
* Initialize the lob storage.
*/
public void init() {
if (init) {
return;
}
synchronized (handler) {
conn = handler.getLobConnection();
init = true;
if (conn == null) {
return;
}
try {
Statement stat = conn.createStatement();
// stat.execute("SET UNDO_LOG 0");
// stat.execute("SET REDO_LOG_BINARY 0");
stat.execute("CREATE TABLE IF NOT EXISTS " + LOBS +
"(ID BIGINT PRIMARY KEY, BYTE_COUNT BIGINT, TABLE INT) HIDDEN");
stat.execute("CREATE INDEX IF NOT EXISTS " +
"INFORMATION_SCHEMA.INDEX_LOB_TABLE ON " + LOBS + "(TABLE)");
stat.execute("CREATE TABLE IF NOT EXISTS " + LOB_MAP +
"(LOB BIGINT, SEQ INT, POS BIGINT, HASH INT, BLOCK BIGINT, PRIMARY KEY(LOB, SEQ)) HIDDEN");
// TODO the column name OFFSET was used in version 1.3.156,
// so this can be remove in a later version
stat.execute("ALTER TABLE " + LOB_MAP + " RENAME TO " + LOB_MAP + " HIDDEN");
stat.execute("ALTER TABLE " + LOB_MAP + " ADD IF NOT EXISTS POS BIGINT BEFORE HASH");
stat.execute("ALTER TABLE " + LOB_MAP + " DROP COLUMN IF EXISTS \"OFFSET\"");
stat.execute("CREATE INDEX IF NOT EXISTS " +
"INFORMATION_SCHEMA.INDEX_LOB_MAP_DATA_LOB ON " + LOB_MAP + "(BLOCK, LOB)");
stat.execute("CREATE TABLE IF NOT EXISTS " + LOB_DATA +
"(BLOCK BIGINT PRIMARY KEY, COMPRESSED INT, DATA BINARY) HIDDEN");
ResultSet rs;
rs = stat.executeQuery("SELECT MAX(BLOCK) FROM " + LOB_DATA);
rs.next();
nextBlock = rs.getLong(1) + 1;
stat.close();
} catch (SQLException e) {
throw DbException.convert(e);
}
}
}
private long getNextLobId() throws SQLException {
String sql = "SELECT MAX(LOB) FROM " + LOB_MAP;
PreparedStatement prep = prepare(sql);
ResultSet rs = prep.executeQuery();
rs.next();
long x = rs.getLong(1) + 1;
reuse(sql, prep);
sql = "SELECT MAX(ID) FROM " + LOBS;
prep = prepare(sql);
rs = prep.executeQuery();
rs.next();
x = Math.max(x, rs.getLong(1) + 1);
reuse(sql, prep);
return x;
}
/**
* Remove all LOBs for this table.
*
* @param tableId the table id
*/
public void removeAllForTable(int tableId) {
if (SysProperties.LOB_IN_DATABASE) {
init();
try {
String sql = "SELECT ID FROM " + LOBS + " WHERE TABLE = ?";
PreparedStatement prep = prepare(sql);
prep.setInt(1, tableId);
ResultSet rs = prep.executeQuery();
while (rs.next()) {
removeLob(rs.getLong(1));
}
reuse(sql, prep);
} catch (SQLException e) {
throw DbException.convert(e);
}
if (tableId == TABLE_ID_SESSION_VARIABLE) {
removeAllForTable(TABLE_TEMP);
}
// remove both lobs in the database as well as in the file system
// (compatibility)
}
ValueLob.removeAllForTable(handler, tableId);
}
/**
* Create a LOB object that fits in memory.
*
* @param type the value type
* @param small the byte array
* @return the LOB
*/
public static Value createSmallLob(int type, byte[] small) {
if (SysProperties.LOB_IN_DATABASE) {
int precision;
if (type == Value.CLOB) {
precision = StringUtils.utf8Decode(small).length();
} else {
precision = small.length;
}
return ValueLobDb.createSmallLob(type, small, precision);
}
return ValueLob.createSmallLob(type, small);
}
/**
* Read a block of data from the given LOB.
*
* @param lob the lob id
* @param seq the block sequence number
* @return the block (expanded if stored compressed)
*/
byte[] readBlock(long lob, int seq) throws SQLException {
synchronized (handler) {
String sql = "SELECT COMPRESSED, DATA FROM " + LOB_MAP + " M " +
"INNER JOIN " + LOB_DATA + " D ON M.BLOCK = D.BLOCK " +
"WHERE M.LOB = ? AND M.SEQ = ?";
PreparedStatement prep = prepare(sql);
prep.setLong(1, lob);
prep.setInt(2, seq);
ResultSet rs = prep.executeQuery();
if (!rs.next()) {
throw DbException.get(ErrorCode.IO_EXCEPTION_1, "Missing lob entry: "+ lob + "/" + seq).getSQLException();
}
int compressed = rs.getInt(1);
byte[] buffer = rs.getBytes(2);
if (compressed != 0) {
buffer = compress.expand(buffer);
}
reuse(sql, prep);
return buffer;
}
}
/**
* Retrieve the sequence id and position that is smaller than the requested
* position. Those values can be used to quickly skip to a given position
* without having to read all data.
*
* @param lob the lob
* @param pos the required position
* @return null if the data is not available, or an array of two elements:
* the sequence, and the offset
*/
long[] skipBuffer(long lob, long pos) throws SQLException {
synchronized (handler) {
String sql = "SELECT MAX(SEQ), MAX(POS) FROM " + LOB_MAP +
" WHERE LOB = ? AND POS < ?";
PreparedStatement prep = prepare(sql);
prep.setLong(1, lob);
prep.setLong(2, pos);
ResultSet rs = prep.executeQuery();
rs.next();
int seq = rs.getInt(1);
pos = rs.getLong(2);
boolean wasNull = rs.wasNull();
rs.close();
reuse(sql, prep);
// upgraded: offset not set
return wasNull ? null : new long[]{seq, pos};
}
}
/**
* An input stream that reads from a LOB.
*/
public class LobInputStream extends InputStream {
private byte[] buffer;
private long length;
private int pos;
private long remainingBytes;
private long lob;
private int seq;
public LobInputStream(long lob, long byteCount) {
this.lob = lob;
remainingBytes = byteCount;
this.length = byteCount;
}
public int read() throws IOException {
fillBuffer();
if (remainingBytes <= 0) {
return -1;
}
remainingBytes--;
return buffer[pos++] & 255;
}
public long skip(long n) throws IOException {
n -= skipSmall(n);
if (n > BLOCK_LENGTH) {
long toPos = length - remainingBytes + n;
try {
long[] seqPos = skipBuffer(lob, toPos);
if (seqPos == null) {
return super.skip(n);
}
seq = (int) seqPos[0];
n = toPos - seqPos[1];
} catch (SQLException e) {
throw DbException.convertToIOException(e);
}
pos = 0;
buffer = null;
}
fillBuffer();
n -= skipSmall(n);
return super.skip(n);
}
private int skipSmall(long n) {
if (n > 0 && buffer != null && pos < buffer.length) {
int x = MathUtils.convertLongToInt(Math.min(n, buffer.length - pos));
n -= x;
pos += x;
remainingBytes -= x;
return x;
}
return 0;
}
public int read(byte[] buff) throws IOException {
return readFully(buff, 0, buff.length);
}
public int read(byte[] buff, int off, int length) throws IOException {
return readFully(buff, off, length);
}
private int readFully(byte[] buff, int off, int length) throws IOException {
if (length == 0) {
return 0;
}
int read = 0;
while (length > 0) {
fillBuffer();
if (remainingBytes <= 0) {
break;
}
int len = (int) Math.min(length, remainingBytes);
len = Math.min(len, buffer.length - pos);
System.arraycopy(buffer, pos, buff, off, len);
pos += len;
read += len;
remainingBytes -= len;
off += len;
length -= len;
}
return read == 0 ? -1 : read;
}
private void fillBuffer() throws IOException {
if (buffer != null && pos < buffer.length) {
return;
}
if (remainingBytes <= 0) {
return;
}
try {
buffer = readBlock(lob, seq++);
pos = 0;
} catch (SQLException e) {
throw DbException.convertToIOException(e);
}
}
}
private PreparedStatement prepare(String sql) throws SQLException {
if (SysProperties.CHECK2) {
if (!Thread.holdsLock(handler)) {
throw DbException.throwInternalError();
}
}
PreparedStatement prep = prepared.remove(sql);
if (prep == null) {
prep = conn.prepareStatement(sql);
}
return prep;
}
private void reuse(String sql, PreparedStatement prep) {
if (SysProperties.CHECK2) {
if (!Thread.holdsLock(handler)) {
throw DbException.throwInternalError();
}
}
prepared.put(sql, prep);
}
/**
* Delete a LOB from the database.
*
* @param lob the lob id
*/
public void removeLob(long lob) {
try {
synchronized (handler) {
if (conn == null) {
return;
}
String sql = "SELECT BLOCK, HASH FROM " + LOB_MAP + " D WHERE D.LOB = ? " +
"AND NOT EXISTS(SELECT 1 FROM " + LOB_MAP + " O " +
"WHERE O.BLOCK = D.BLOCK AND O.LOB <> ?)";
PreparedStatement prep = prepare(sql);
prep.setLong(1, lob);
prep.setLong(2, lob);
ResultSet rs = prep.executeQuery();
ArrayList<Long> blocks = New.arrayList();
while (rs.next()) {
blocks.add(rs.getLong(1));
int hash = rs.getInt(2);
setHashCacheBlock(hash, -1);
}
reuse(sql, prep);
sql = "DELETE FROM " + LOB_MAP + " WHERE LOB = ?";
prep = prepare(sql);
prep.setLong(1, lob);
prep.execute();
reuse(sql, prep);
sql = "DELETE FROM " + LOB_DATA + " WHERE BLOCK = ?";
prep = prepare(sql);
for (long block : blocks) {
prep.setLong(1, block);
prep.execute();
}
reuse(sql, prep);
sql = "DELETE FROM " + LOBS + " WHERE ID = ?";
prep = prepare(sql);
prep.setLong(1, lob);
prep.execute();
reuse(sql, prep);
}
} catch (SQLException e) {
throw DbException.convert(e);
}
}
/**
* Get the input stream for the given lob.
*
* @param lobId the lob id
* @param byteCount the number of bytes to read, or -1 if not known
* @return the stream
*/
public InputStream getInputStream(long lobId, long byteCount) throws IOException {
init();
if (byteCount == -1) {
synchronized (handler) {
try {
String sql = "SELECT BYTE_COUNT FROM " + LOBS + " WHERE ID = ?";
PreparedStatement prep = prepare(sql);
prep.setLong(1, lobId);
ResultSet rs = prep.executeQuery();
if (!rs.next()) {
throw DbException.get(ErrorCode.IO_EXCEPTION_1, "Missing lob: "+ lobId).getSQLException();
}
byteCount = rs.getLong(1);
reuse(sql, prep);
} catch (SQLException e) {
throw DbException.convertToIOException(e);
}
}
}
return new LobInputStream(lobId, byteCount);
}
private ValueLobDb addLob(InputStream in, long maxLength, int type) {
try {
byte[] buff = new byte[BLOCK_LENGTH];
if (maxLength < 0) {
maxLength = Long.MAX_VALUE;
}
long length = 0;
long lobId = -1;
int maxLengthInPlaceLob = handler.getMaxLengthInplaceLob();
String compressAlgorithm = handler.getLobCompressionAlgorithm(type);
try {
byte[] small = null;
for (int seq = 0; maxLength > 0; seq++) {
int len = (int) Math.min(BLOCK_LENGTH, maxLength);
len = IOUtils.readFully(in, buff, 0, len);
if (len <= 0) {
break;
}
maxLength -= len;
byte[] b;
if (len != buff.length) {
b = new byte[len];
System.arraycopy(buff, 0, b, 0, len);
} else {
b = buff;
}
if (seq == 0 && b.length < BLOCK_LENGTH && b.length <= maxLengthInPlaceLob) {
small = b;
break;
}
synchronized (handler) {
if (seq == 0) {
lobId = getNextLobId();
}
storeBlock(lobId, seq, length, b, compressAlgorithm);
}
length += len;
}
if (lobId == -1 && small == null) {
// zero length
small = new byte[0];
}
if (small != null) {
// CLOB: the precision will be fixed later
ValueLobDb v = ValueLobDb.createSmallLob(type, small, small.length);
return v;
}
return registerLob(type, lobId, TABLE_TEMP, length);
} catch (IOException e) {
if (lobId != -1) {
removeLob(lobId);
}
throw DbException.convertIOException(e, null);
}
} catch (SQLException e) {
throw DbException.convert(e);
}
}
private ValueLobDb registerLob(int type, long lobId, int tableId, long byteCount) {
synchronized (handler) {
try {
String sql = "INSERT INTO " + LOBS + "(ID, BYTE_COUNT, TABLE) VALUES(?, ?, ?)";
PreparedStatement prep = prepare(sql);
prep.setLong(1, lobId);
prep.setLong(2, byteCount);
prep.setInt(3, tableId);
prep.execute();
reuse(sql, prep);
ValueLobDb v = ValueLobDb.create(type, this, null, tableId, lobId, byteCount);
return v;
} catch (SQLException e) {
throw DbException.convert(e);
}
}
}
/**
* Copy a lob.
*
* @param type the type
* @param oldLobId the old lob id
* @param tableId the new table id
* @param length the length
* @return the new lob
*/
public ValueLobDb copyLob(int type, long oldLobId, int tableId, long length) {
synchronized (handler) {
try {
init();
long lobId = getNextLobId();
String sql = "INSERT INTO " + LOB_MAP + "(LOB, SEQ, POS, HASH, BLOCK) " +
"SELECT ?, SEQ, POS, HASH, BLOCK FROM " + LOB_MAP + " WHERE LOB = ?";
PreparedStatement prep = prepare(sql);
prep.setLong(1, lobId);
prep.setLong(2, oldLobId);
prep.executeUpdate();
reuse(sql, prep);
sql = "INSERT INTO " + LOBS + "(ID, BYTE_COUNT, TABLE) " +
"SELECT ?, BYTE_COUNT, ? FROM " + LOBS + " WHERE ID = ?";
prep = prepare(sql);
prep.setLong(1, lobId);
prep.setLong(2, tableId);
prep.setLong(3, oldLobId);
prep.executeUpdate();
reuse(sql, prep);
ValueLobDb v = ValueLobDb.create(type, this, null, tableId, lobId, length);
return v;
} catch (SQLException e) {
throw DbException.convert(e);
}
}
}
private long getHashCacheBlock(int hash) {
if (HASH_CACHE_SIZE > 0) {
int index = hash & (HASH_CACHE_SIZE - 1);
long oldHash = hashBlocks[index];
if (oldHash == hash) {
return hashBlocks[index + HASH_CACHE_SIZE];
}
}
return -1;
}
private void setHashCacheBlock(int hash, long block) {
if (HASH_CACHE_SIZE > 0) {
int index = hash & (HASH_CACHE_SIZE - 1);
hashBlocks[index] = hash;
hashBlocks[index + HASH_CACHE_SIZE] = block;
}
}
/**
* Store a block in the LOB storage.
*
* @param lobId the lob id
* @param seq the sequence number
* @param pos the position within the lob
* @param b the data
* @param compressAlgorithm the compression algorithm (may be null)
*/
void storeBlock(long lobId, int seq, long pos, byte[] b, String compressAlgorithm) throws SQLException {
long block;
boolean blockExists = false;
if (compressAlgorithm != null) {
b = compress.compress(b, compressAlgorithm);
}
int hash = Arrays.hashCode(b);
synchronized (handler) {
block = getHashCacheBlock(hash);
if (block != -1) {
String sql = "SELECT COMPRESSED, DATA FROM " + LOB_DATA +
" WHERE BLOCK = ?";
PreparedStatement prep = prepare(sql);
prep.setLong(1, block);
ResultSet rs = prep.executeQuery();
if (rs.next()) {
boolean compressed = rs.getInt(1) != 0;
byte[] compare = rs.getBytes(2);
if (compressed == (compressAlgorithm != null) && Arrays.equals(b, compare)) {
blockExists = true;
}
}
reuse(sql, prep);
}
if (!blockExists) {
block = nextBlock++;
setHashCacheBlock(hash, block);
String sql = "INSERT INTO " + LOB_DATA + "(BLOCK, COMPRESSED, DATA) VALUES(?, ?, ?)";
PreparedStatement prep = prepare(sql);
prep.setLong(1, block);
prep.setInt(2, compressAlgorithm == null ? 0 : 1);
prep.setBytes(3, b);
prep.execute();
reuse(sql, prep);
}
String sql = "INSERT INTO " + LOB_MAP + "(LOB, SEQ, POS, HASH, BLOCK) VALUES(?, ?, ?, ?, ?)";
PreparedStatement prep = prepare(sql);
prep.setLong(1, lobId);
prep.setInt(2, seq);
prep.setLong(3, pos);
prep.setLong(4, hash);
prep.setLong(5, block);
prep.execute();
reuse(sql, prep);
}
}
/**
* An input stream that reads the data from a reader.
*/
static class CountingReaderInputStream extends InputStream {
private final Reader reader;
private long length;
private long remaining;
private int pos;
private char[] charBuffer = new char[Constants.IO_BUFFER_SIZE];
private byte[] buffer;
CountingReaderInputStream(Reader reader, long maxLength) {
this.reader = reader;
this.remaining = maxLength;
buffer = Utils.EMPTY_BYTES;
}
public int read(byte[] buff, int offset, int len) throws IOException {
if (buffer == null) {
return -1;
}
if (pos >= buffer.length) {
fillBuffer();
if (buffer == null) {
return -1;
}
}
len = Math.min(len, buffer.length - pos);
System.arraycopy(buffer, pos, buff, offset, len);
pos += len;
return len;
}
public int read() throws IOException {
if (buffer == null) {
return -1;
}
if (pos >= buffer.length) {
fillBuffer();
if (buffer == null) {
return -1;
}
}
return buffer[pos++];
}
private void fillBuffer() throws IOException {
int len = (int) Math.min(charBuffer.length, remaining);
if (len > 0) {
len = reader.read(charBuffer, 0, len);
} else {
len = -1;
}
if (len < 0) {
buffer = null;
} else {
buffer = StringUtils.utf8Encode(new String(charBuffer, 0, len));
length += len;
remaining -= len;
}
pos = 0;
}
public long getLength() {
return length;
}
public void close() throws IOException {
reader.close();
}
}
/**
* Create a BLOB object.
*
* @param in the input stream
* @param maxLength the maximum length (-1 if not known)
* @return the LOB
*/
public Value createBlob(InputStream in, long maxLength) {
if (SysProperties.LOB_IN_DATABASE) {
init();
if (conn == null) {
return ValueLobDb.createTempBlob(in, maxLength, handler);
}
return addLob(in, maxLength, Value.BLOB);
}
return ValueLob.createBlob(in, maxLength, handler);
}
/**
* Create a CLOB object.
*
* @param reader the reader
* @param maxLength the maximum length (-1 if not known)
* @return the LOB
*/
public Value createClob(Reader reader, long maxLength) {
if (SysProperties.LOB_IN_DATABASE) {
init();
if (conn == null) {
return ValueLobDb.createTempClob(reader, maxLength, handler);
}
long max = maxLength == -1 ? Long.MAX_VALUE : maxLength;
CountingReaderInputStream in = new CountingReaderInputStream(reader, max);
ValueLobDb lob = addLob(in, Long.MAX_VALUE, Value.CLOB);
lob.setPrecision(in.getLength());
return lob;
}
return ValueLob.createClob(reader, maxLength, handler);
}
/**
* Set the table reference of this lob.
*
* @param lobId the lob
* @param table the table
*/
public void setTable(long lobId, int table) {
synchronized (handler) {
try {
init();
String sql = "UPDATE " + LOBS + " SET TABLE = ? WHERE ID = ?";
PreparedStatement prep = prepare(sql);
prep.setInt(1, table);
prep.setLong(2, lobId);
prep.executeUpdate();
reuse(sql, prep);
} catch (SQLException e) {
throw DbException.convert(e);
}
}
}
}