/**
* Preconditions: 1. xid must be in prepared state in the server
*
* <p>Implementation deficiency preconditions: 1. Connection must be in idle state
*
* <p>Postconditions: 1. Transaction is committed
*/
private void commitPrepared(Xid xid) throws XAException {
try {
// Check preconditions. The connection mustn't be used for another
// other XA or local transaction, or the COMMIT PREPARED command
// would mess it up.
if (state != STATE_IDLE || conn.getTransactionState() != ProtocolConnection.TRANSACTION_IDLE)
throw new PGXAException(
GT.tr("Not implemented: 2nd phase commit must be issued using an idle connection"),
XAException.XAER_RMERR);
String s = RecoveredXid.xidToString(xid);
localAutoCommitMode = conn.getAutoCommit();
conn.setAutoCommit(true);
Statement stmt = conn.createStatement();
try {
stmt.executeUpdate("COMMIT PREPARED '" + s + "'");
} finally {
stmt.close();
conn.setAutoCommit(localAutoCommitMode);
}
} catch (SQLException ex) {
throw new PGXAException(
GT.tr("Error committing prepared transaction"), ex, XAException.XAER_RMERR);
}
}
/**
* Preconditions: 1. xid is known to the RM or it's in prepared state
*
* <p>Implementation deficiency preconditions: 1. xid must be associated with this connection if
* it's not in prepared state.
*
* <p>Postconditions: 1. Transaction is rolled back and disassociated from connection
*/
public void rollback(Xid xid) throws XAException {
if (logger.logDebug()) debug("rolling back xid = " + xid);
// We don't explicitly check precondition 1.
try {
if (currentXid != null && xid.equals(currentXid)) {
state = STATE_IDLE;
currentXid = null;
conn.rollback();
conn.setAutoCommit(localAutoCommitMode);
} else {
String s = RecoveredXid.xidToString(xid);
conn.setAutoCommit(true);
Statement stmt = conn.createStatement();
try {
stmt.executeUpdate("ROLLBACK PREPARED '" + s + "'");
} finally {
stmt.close();
}
}
} catch (SQLException ex) {
throw new PGXAException(
GT.tr("Error rolling back prepared transaction"), ex, XAException.XAER_RMERR);
}
}
/**
* Preconditions: 1. flag must be one of TMSTARTRSCAN, TMENDRSCAN, TMNOFLAGS or TMSTARTTRSCAN |
* TMENDRSCAN 2. if flag isn't TMSTARTRSCAN or TMSTARTRSCAN | TMENDRSCAN, a recovery scan must be
* in progress
*
* <p>Postconditions: 1. list of prepared xids is returned
*/
public Xid[] recover(int flag) throws XAException {
// Check preconditions
if (flag != TMSTARTRSCAN
&& flag != TMENDRSCAN
&& flag != TMNOFLAGS
&& flag != (TMSTARTRSCAN | TMENDRSCAN))
throw new PGXAException(GT.tr("Invalid flag"), XAException.XAER_INVAL);
// We don't check for precondition 2, because we would have to add some additional state in
// this object to keep track of recovery scans.
// All clear. We return all the xids in the first TMSTARTRSCAN call, and always return
// an empty array otherwise.
if ((flag & TMSTARTRSCAN) == 0) return new Xid[0];
else {
try {
Statement stmt = conn.createStatement();
try {
// If this connection is simultaneously used for a transaction,
// this query gets executed inside that transaction. It's OK,
// except if the transaction is in abort-only state and the
// backed refuses to process new queries. Hopefully not a problem
// in practise.
ResultSet rs = stmt.executeQuery("SELECT gid FROM pg_prepared_xacts");
LinkedList l = new LinkedList();
while (rs.next()) {
Xid recoveredXid = RecoveredXid.stringToXid(rs.getString(1));
if (recoveredXid != null) l.add(recoveredXid);
}
rs.close();
return (Xid[]) l.toArray(new Xid[l.size()]);
} finally {
stmt.close();
}
} catch (SQLException ex) {
throw new PGXAException(GT.tr("Error during recover"), ex, XAException.XAER_RMERR);
}
}
}
/**
* Preconditions: 1. xid != null 2. xid is in ended state
*
* <p>Implementation deficiency preconditions: 1. xid was associated with this connection
*
* <p>Postconditions: 1. Transaction is prepared
*/
public int prepare(Xid xid) throws XAException {
if (logger.logDebug()) debug("preparing transaction xid = " + xid);
// Check preconditions
if (!currentXid.equals(xid)) {
throw new PGXAException(
GT.tr(
"Not implemented: Prepare must be issued using the same connection that started the transaction"),
XAException.XAER_RMERR);
}
if (state != STATE_ENDED)
throw new PGXAException(GT.tr("Prepare called before end"), XAException.XAER_INVAL);
state = STATE_IDLE;
currentXid = null;
if (!conn.haveMinimumServerVersion("8.1"))
throw new PGXAException(
GT.tr("Server versions prior to 8.1 do not support two-phase commit."),
XAException.XAER_RMERR);
try {
String s = RecoveredXid.xidToString(xid);
Statement stmt = conn.createStatement();
try {
stmt.executeUpdate("PREPARE TRANSACTION '" + s + "'");
} finally {
stmt.close();
}
conn.setAutoCommit(localAutoCommitMode);
return XA_OK;
} catch (SQLException ex) {
throw new PGXAException(GT.tr("Error preparing transaction"), ex, XAException.XAER_RMERR);
}
}