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JDBC Driver for the Firebird RDBMS
/*
* Firebird Open Source JDBC Driver
*
* Distributable under LGPL license.
* You may obtain a copy of the License at http://www.gnu.org/copyleft/lgpl.html
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* LGPL License for more details.
*
* This file was created by members of the firebird development team.
* All individual contributions remain the Copyright (C) of those
* individuals. Contributors to this file are either listed here or
* can be obtained from a source control history command.
*
* All rights reserved.
*/
package org.firebirdsql.jaybird.xca;
import javax.transaction.xa.Xid;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
import java.util.Arrays;
/**
* The class {@code FBXid} has methods for serializing xids for
* firebird use, and reading them back into instances of itself. It is
* a key component in adapting xa semantics and recovery to firebird
* native operations and data format.
*
* @author David Jencks
*/
final class FBXid implements Xid {
// Constant from alice.h
private static final int TDR_VERSION = 1;
// constants for xid encoding as used by Jaybird
private static final int TDR_XID_FORMAT_ID = 5;
private static final int TDR_XID_GLOBAL_ID = 6;
private static final int TDR_XID_BRANCH_ID = 4;
private final int formatId;
/**
* Global transaction id of this instance.
*/
private final byte[] globalId;
/**
* Branch qualifier of this instance.
* This identifies the branch of a transaction.
*/
private final byte[] branchId;
private final long firebirdTransactionId;
/**
* Return a string that describes any Xid instance.
*/
static String toString(Xid id) {
if (id == null)
return "[NULL Xid]";
String s = id.getClass().getName();
s = s.substring(s.lastIndexOf('.') + 1);
s = s + " [FormatId=" + id.getFormatId() +
", GlobalId=" + new String(id.getGlobalTransactionId()).trim() +
", BranchQual=" + new String(id.getBranchQualifier()).trim() + "]";
return s;
}
/**
* Create a xid with the specified values.
*
* @param firebirdTransactionId
* Firebird transaction id
* @param formatId
* format id
* @param globalId
* global transaction id
* @param branchId
* branch qualifier
*/
FBXid(long firebirdTransactionId, int formatId, byte[] globalId, byte[] branchId) {
this.firebirdTransactionId = firebirdTransactionId;
this.formatId = formatId;
this.globalId = globalId;
this.branchId = branchId;
}
/**
* Create a new instance copying an existing one.
*
* @param xid
* source xid
*/
FBXid(Xid xid) {
this(0L, xid.getFormatId(), xid.getGlobalTransactionId(), xid.getBranchQualifier());
}
/**
* Creates a new xid instance from the byte representation supplied. This is called by recover to reconstruct a xid
* from the toBytes() representation.
*
* @param rawIn
* Xid serialized in format of {@link #toBytes()}
* @param firebirdTransactionId
* The Firebird transactionId of the recovered Xid.
* @throws FBIncorrectXidException
* if an unexpected value is read from the input stream
*/
FBXid(byte[] rawIn, long firebirdTransactionId) throws FBIncorrectXidException {
this.firebirdTransactionId = firebirdTransactionId;
ByteBuffer buffer = ByteBuffer.wrap(rawIn);
try {
if (buffer.get() != TDR_VERSION) {
throw new FBIncorrectXidException("Wrong TDR_VERSION for xid");
}
if (buffer.get() != TDR_XID_FORMAT_ID) {
throw new FBIncorrectXidException("Wrong TDR_XID_FORMAT_ID for xid");
}
formatId = buffer.getInt();
if (buffer.get() != TDR_XID_GLOBAL_ID) {
throw new FBIncorrectXidException("Wrong TDR_XID_GLOBAL_ID for xid");
}
globalId = readBuffer(buffer);
if (buffer.get() != TDR_XID_BRANCH_ID) {
throw new FBIncorrectXidException("Wrong TDR_XID_BRANCH_ID for xid");
}
branchId = readBuffer(buffer);
} catch (BufferUnderflowException e) {
throw new FBIncorrectXidException("Unexpected format or incomplete serialized xid", e);
}
}
/**
* @return the global transaction id of this transaction.
*/
public byte[] getGlobalTransactionId() {
return globalId.clone();
}
/**
* @return the branch qualifier of this transaction.
*/
public byte[] getBranchQualifier() {
return branchId.clone();
}
/**
* The format identifier augments the global id and specifies
* how the global id and branch qualifier should be interpreted.
*
* @return the format identifier of this transaction.
*/
public int getFormatId() {
return formatId;
}
/**
* @return Firebird transaction ID or 0 if no transaction id is available.
*/
public long getFirebirdTransactionId() {
return firebirdTransactionId;
}
/**
* Compare for equality.
*
* Instances are considered equal if they are both instances of FBXid, and if they have the same global
* transaction id and transaction branch qualifier.
*
*/
public boolean equals(Object obj) {
if (this == obj) return true;
if (!(obj instanceof Xid)) return false;
Xid other = (Xid) obj;
boolean result = formatId == other.getFormatId();
byte[] otherGlobalID = other.getGlobalTransactionId();
byte[] otherBranchID = other.getBranchQualifier();
result &= Arrays.equals(globalId, otherGlobalID);
result &= Arrays.equals(branchId, otherBranchID);
return result;
}
public int hashCode() {
int hashCode = 1109;
hashCode = 43 * hashCode + formatId;
hashCode = 43 * hashCode + Arrays.hashCode(globalId);
hashCode = 43 * hashCode + Arrays.hashCode(branchId);
return hashCode;
}
public String toString() {
return toString(this);
}
/**
* @return Serialized byte representation of this Xid
*/
byte[] toBytes() {
byte[] b = new byte[1 + 1 + 4 + 1 + 4 + globalId.length + 1 + 4 + branchId.length];
ByteBuffer.wrap(b)
.put((byte) TDR_VERSION)
.put((byte) TDR_XID_FORMAT_ID)
.putInt(formatId)
.put((byte) TDR_XID_GLOBAL_ID)
.putInt(globalId.length)
.put(globalId)
.put((byte) TDR_XID_BRANCH_ID)
.putInt(branchId.length)
.put(branchId);
return b;
}
private byte[] readBuffer(ByteBuffer buffer) {
byte[] content = new byte[buffer.getInt()];
buffer.get(content);
return content;
}
}
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