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Java JDBC 4.2 (JRE 8+) driver for Redshift database
/*
* Copyright (c) 2005, PostgreSQL Global Development Group
* See the LICENSE file in the project root for more information.
*/
package com.amazon.redshift.jdbc;
import com.amazon.redshift.core.BaseConnection;
import com.amazon.redshift.core.ServerVersion;
import com.amazon.redshift.largeobject.LargeObject;
import com.amazon.redshift.largeobject.LargeObjectManager;
import com.amazon.redshift.util.GT;
import com.amazon.redshift.util.RedshiftException;
import com.amazon.redshift.util.RedshiftState;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.SQLException;
import java.util.ArrayList;
/**
* This class holds all of the methods common to both Blobs and Clobs.
*
* @author Michael Barker
*/
public abstract class AbstractBlobClob {
protected BaseConnection conn;
private LargeObject currentLo;
private boolean currentLoIsWriteable;
private boolean support64bit;
/**
* We create separate LargeObjects for methods that use streams so they won't interfere with each
* other.
*/
private ArrayList subLOs;
private final long oid;
public AbstractBlobClob(BaseConnection conn, long oid) throws SQLException {
this.conn = conn;
this.oid = oid;
this.currentLo = null;
this.currentLoIsWriteable = false;
support64bit = conn.haveMinimumServerVersion(90300);
subLOs = new ArrayList();
}
public synchronized void free() throws SQLException {
if (currentLo != null) {
currentLo.close();
currentLo = null;
currentLoIsWriteable = false;
}
for (LargeObject subLO : subLOs) {
subLO.close();
}
subLOs = null;
}
/**
* For Blobs this should be in bytes while for Clobs it should be in characters. Since we really
* haven't figured out how to handle character sets for Clobs the current implementation uses
* bytes for both Blobs and Clobs.
*
* @param len maximum length
* @throws SQLException if operation fails
*/
public synchronized void truncate(long len) throws SQLException {
checkFreed();
if (!conn.haveMinimumServerVersion(ServerVersion.v8_3)) {
throw new RedshiftException(
GT.tr("Truncation of large objects is only implemented in 8.3 and later servers."),
RedshiftState.NOT_IMPLEMENTED);
}
if (len < 0) {
throw new RedshiftException(GT.tr("Cannot truncate LOB to a negative length."),
RedshiftState.INVALID_PARAMETER_VALUE);
}
if (len > Integer.MAX_VALUE) {
if (support64bit) {
getLo(true).truncate64(len);
} else {
throw new RedshiftException(GT.tr("Redshift LOBs can only index to: {0}", Integer.MAX_VALUE),
RedshiftState.INVALID_PARAMETER_VALUE);
}
} else {
getLo(true).truncate((int) len);
}
}
public synchronized long length() throws SQLException {
checkFreed();
if (support64bit) {
return getLo(false).size64();
} else {
return getLo(false).size();
}
}
public synchronized byte[] getBytes(long pos, int length) throws SQLException {
assertPosition(pos);
getLo(false).seek((int) (pos - 1), LargeObject.SEEK_SET);
return getLo(false).read(length);
}
public synchronized InputStream getBinaryStream() throws SQLException {
checkFreed();
LargeObject subLO = getLo(false).copy();
addSubLO(subLO);
subLO.seek(0, LargeObject.SEEK_SET);
return subLO.getInputStream();
}
public synchronized OutputStream setBinaryStream(long pos) throws SQLException {
assertPosition(pos);
LargeObject subLO = getLo(true).copy();
addSubLO(subLO);
subLO.seek((int) (pos - 1));
return subLO.getOutputStream();
}
/**
* Iterate over the buffer looking for the specified pattern.
*
* @param pattern A pattern of bytes to search the blob for
* @param start The position to start reading from
* @return position of the specified pattern
* @throws SQLException if something wrong happens
*/
public synchronized long position(byte[] pattern, long start) throws SQLException {
assertPosition(start, pattern.length);
int position = 1;
int patternIdx = 0;
long result = -1;
int tmpPosition = 1;
for (LOIterator i = new LOIterator(start - 1); i.hasNext(); position++) {
byte b = i.next();
if (b == pattern[patternIdx]) {
if (patternIdx == 0) {
tmpPosition = position;
}
patternIdx++;
if (patternIdx == pattern.length) {
result = tmpPosition;
break;
}
} else {
patternIdx = 0;
}
}
return result;
}
/**
* Iterates over a large object returning byte values. Will buffer the data from the large object.
*/
private class LOIterator {
private static final int BUFFER_SIZE = 8096;
private byte[] buffer = new byte[BUFFER_SIZE];
private int idx = BUFFER_SIZE;
private int numBytes = BUFFER_SIZE;
LOIterator(long start) throws SQLException {
getLo(false).seek((int) start);
}
public boolean hasNext() throws SQLException {
boolean result;
if (idx < numBytes) {
result = true;
} else {
numBytes = getLo(false).read(buffer, 0, BUFFER_SIZE);
idx = 0;
result = (numBytes > 0);
}
return result;
}
private byte next() {
return buffer[idx++];
}
}
/**
* This is simply passing the byte value of the pattern Blob.
*
* @param pattern search pattern
* @param start start position
* @return position of given pattern
* @throws SQLException if something goes wrong
*/
public synchronized long position(Blob pattern, long start) throws SQLException {
return position(pattern.getBytes(1, (int) pattern.length()), start);
}
/**
* Throws an exception if the pos value exceeds the max value by which the large object API can
* index.
*
* @param pos Position to write at.
* @throws SQLException if something goes wrong
*/
protected void assertPosition(long pos) throws SQLException {
assertPosition(pos, 0);
}
/**
* Throws an exception if the pos value exceeds the max value by which the large object API can
* index.
*
* @param pos Position to write at.
* @param len number of bytes to write.
* @throws SQLException if something goes wrong
*/
protected void assertPosition(long pos, long len) throws SQLException {
checkFreed();
if (pos < 1) {
throw new RedshiftException(GT.tr("LOB positioning offsets start at 1."),
RedshiftState.INVALID_PARAMETER_VALUE);
}
if (pos + len - 1 > Integer.MAX_VALUE) {
throw new RedshiftException(GT.tr("Redshift LOBs can only index to: {0}", Integer.MAX_VALUE),
RedshiftState.INVALID_PARAMETER_VALUE);
}
}
/**
* Checks that this LOB hasn't been free()d already.
*
* @throws SQLException if LOB has been freed.
*/
protected void checkFreed() throws SQLException {
if (subLOs == null) {
throw new RedshiftException(GT.tr("free() was called on this LOB previously"),
RedshiftState.OBJECT_NOT_IN_STATE);
}
}
protected synchronized LargeObject getLo(boolean forWrite) throws SQLException {
if (this.currentLo != null) {
if (forWrite && !currentLoIsWriteable) {
// Reopen the stream in read-write, at the same pos.
int currentPos = this.currentLo.tell();
LargeObjectManager lom = conn.getLargeObjectAPI();
LargeObject newLo = lom.open(oid, LargeObjectManager.READWRITE);
this.subLOs.add(this.currentLo);
this.currentLo = newLo;
if (currentPos != 0) {
this.currentLo.seek(currentPos);
}
}
return this.currentLo;
}
LargeObjectManager lom = conn.getLargeObjectAPI();
currentLo = lom.open(oid, forWrite ? LargeObjectManager.READWRITE : LargeObjectManager.READ);
currentLoIsWriteable = forWrite;
return currentLo;
}
protected void addSubLO(LargeObject subLO) {
subLOs.add(subLO);
}
}