We need to ensure that only one repository operation is active on a particular
JDBC connection at a time. JDBC connections are thread safe, but we frequently have to execute statements like: insert into FOO values(0, blah, blah); select LAST_INSERTED_ID() to get the value assigned to an auto-increment column. If another thread slipped in between those statements and inserted something into its own auto-increment column having table, we'd get funny business. And indeed we very occasionally see this race condition happen in the thread-happy webapps. git-svn-id: https://samskivert.googlecode.com/svn/trunk@1838 6335cc39-0255-0410-8fd6-9bcaacd3b74c
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mdb
@@ -142,104 +142,111 @@ public class SimpleRepository extends Repository
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Thread.dumpStack();
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}
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try {
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// obtain our database connection and associated goodies
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conn = _provider.getConnection(_dbident, readOnly);
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liaison = LiaisonRegistry.getLiaison(conn);
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// obtain our database connection and associated goodies
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conn = _provider.getConnection(_dbident, readOnly);
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// find out if we support transactions
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DatabaseMetaData dmd = conn.getMetaData();
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if (dmd != null) {
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supportsTransactions = dmd.supportsTransactions();
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}
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// make sure that no one else performs a database operation using the
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// same connection until we're done
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synchronized (conn) {
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try {
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liaison = LiaisonRegistry.getLiaison(conn);
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// turn off auto-commit
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conn.setAutoCommit(false);
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// find out if we support transactions
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DatabaseMetaData dmd = conn.getMetaData();
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if (dmd != null) {
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supportsTransactions = dmd.supportsTransactions();
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}
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// let derived classes do any got-connection processing
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gotConnection(conn);
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// turn off auto-commit
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conn.setAutoCommit(false);
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// invoke the operation
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attemptedOperation = true;
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rv = op.invoke(conn, liaison);
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// let derived classes do any got-connection processing
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gotConnection(conn);
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// commit the transaction
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if (supportsTransactions) {
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conn.commit();
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}
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// invoke the operation
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attemptedOperation = true;
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rv = op.invoke(conn, liaison);
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// return the operation result
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return rv;
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// commit the transaction
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if (supportsTransactions) {
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conn.commit();
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}
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} catch (SQLException sqe) {
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if (attemptedOperation) {
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// back out our changes if something got hosed (but not if
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// the hosage was a result of losing our connection)
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// return the operation result
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return rv;
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} catch (SQLException sqe) {
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if (attemptedOperation) {
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// back out our changes if something got hosed (but not if
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// the hosage was a result of losing our connection)
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try {
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if (supportsTransactions && !conn.isClosed()) {
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conn.rollback();
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}
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} catch (SQLException rbe) {
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Log.warning("Unable to roll back operation " +
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"[err=" + sqe + ", rberr=" + rbe + "].");
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}
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}
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if (conn != null) {
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// let the provider know that the connection failed
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_provider.connectionFailed(_dbident, readOnly, conn, sqe);
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// clear out the reference so that we don't release it later
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conn = null;
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}
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if (!retryOnTransientFailure || liaison == null ||
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!liaison.isTransientException(sqe)) {
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String err = "Operation invocation failed";
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throw new PersistenceException(err, sqe);
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}
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// the MySQL JDBC driver has the annoying habit of including
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// the embedded exception stack trace in the message of their
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// outer exception; if I want a fucking stack trace, I'll call
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// printStackTrace() thanksverymuch
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String msg = StringUtil.split("" + sqe, "\n")[0];
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Log.info("Transient failure executing operation, " +
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"retrying [error=" + msg + "].");
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} catch (PersistenceException pe) {
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// back out our changes if something got hosed
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try {
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if (supportsTransactions && !conn.isClosed()) {
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conn.rollback();
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}
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} catch (SQLException rbe) {
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Log.warning("Unable to roll back operation " +
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"[origerr=" + sqe + ", rberr=" + rbe + "].");
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"[origerr=" + pe + ", rberr=" + rbe + "].");
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}
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throw pe;
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} catch (RuntimeException rte) {
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// back out our changes if something got hosed
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try {
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if (supportsTransactions &&
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conn != null && !conn.isClosed()) {
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conn.rollback();
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}
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} catch (SQLException rbe) {
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Log.warning("Unable to roll back operation " +
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"[origerr=" + rte + ", rberr=" + rbe + "].");
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}
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throw rte;
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} finally {
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if (conn != null) {
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// release the database connection
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_provider.releaseConnection(_dbident, readOnly, conn);
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}
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}
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}
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if (conn != null) {
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// let the connection provider know that the connection failed
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_provider.connectionFailed(_dbident, readOnly, conn, sqe);
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// clear out the reference so that we don't release it later
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conn = null;
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}
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// if this is a transient failure and we've been requested to
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// retry such failures, try one more time
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if (retryOnTransientFailure &&
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liaison != null && liaison.isTransientException(sqe)) {
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// the MySQL JDBC driver has the annoying habit of
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// including the embedded exception stack trace in the
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// message of their outer exception; if I want a fucking
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// stack trace, I'll call printStackTrace() thanksverymuch
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String msg = StringUtil.split("" + sqe, "\n")[0];
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Log.info("Transient failure executing operation, " +
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"retrying [error=" + msg + "].");
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return execute(op, false, readOnly);
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}
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String err = "Operation invocation failed";
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throw new PersistenceException(err, sqe);
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} catch (PersistenceException pe) {
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// back out our changes if something got hosed
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try {
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if (supportsTransactions && !conn.isClosed()) {
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conn.rollback();
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}
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} catch (SQLException rbe) {
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Log.warning("Unable to roll back operation " +
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"[origerr=" + pe + ", rberr=" + rbe + "].");
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}
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throw pe;
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} catch (RuntimeException rte) {
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// back out our changes if something got hosed
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try {
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if (conn != null && supportsTransactions && !conn.isClosed()) {
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conn.rollback();
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}
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} catch (SQLException rbe) {
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Log.warning("Unable to roll back operation " +
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"[origerr=" + rte + ", rberr=" + rbe + "].");
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}
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throw rte;
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} finally {
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if (conn != null) {
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// release the database connection
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_provider.releaseConnection(_dbident, readOnly, conn);
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}
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}
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// we'll only fall through here if the above code failed due to a
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// transient exception (the connection was closed for being idle, for
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// example) and we've been asked to retry; so let's do so
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return execute(op, false, readOnly);
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}
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/**
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