Re: libpq++: suggested patches for PgTransaction

I will keep this for 7.2. Thanks.

> The original PgTransaction, apparently having been written without exceptions
> in mind, didn't know how to abort a transaction. The suggested change makes
> it abort if the transaction object is destroyed without an explicit commit,
> as would happen if the program fell out of the transaction code through an
> unhandled exception (plus the patch makes constructors explicit where
> appropriate).
>
> Actually this still isn't very effective; I think it would be more useful to
> have a separate transaction object "latch onto" an existing connection and
> represent a single transaction delimited by the object's entire lifetime.
> That would make it easier to perform multiple independent (but presumably
> non-overlapping) transactions over the lifetime of a single connection in
> an exception-safe manner.
>
>
> --- postgresql-7.0.3/src/interfaces/libpq++/pgtransdb.cc Sun May 30 17:17:58 1999
> +++ postgresql-7.0.3-jtv/src/interfaces/libpq++/pgtransdb.cc Wed Feb 28 13:34:20 2001
> @@ -25,7 +25,8 @@
> // Make a connection to the specified database with default environment
> // See PQconnectdb() for conninfo usage.
> PgTransaction::PgTransaction(const char* conninfo)
> - : PgDatabase(conninfo)
> + : PgDatabase(conninfo),
> + pgCommitted(true)
> {
> BeginTransaction();
> }
> @@ -33,17 +34,20 @@
> // Destructor: End the transaction block
> PgTransaction::~PgTransaction()
> {
> - EndTransaction();
> + if (!pgCommitted) Exec("ABORT");
> }
>
> // Begin the transaction block
> ExecStatusType PgTransaction::BeginTransaction()
> {
> + pgCommitted = false;
> return Exec("BEGIN");
> } // End BeginTransaction()
>
> // Begin the transaction block
> ExecStatusType PgTransaction::EndTransaction()
> {
> + pgCommitted = true;
> return Exec("END");
> } // End EndTransaction()
> +
>
>
>
> --- postgresql-7.0.3/src/interfaces/libpq++/pgtransdb.h Sun Apr 23 00:39:15 2000
> +++ postgresql-7.0.3-jtv/src/interfaces/libpq++/pgtransdb.h Wed Feb 28 13:34:42 2001
> @@ -36,9 +36,9 @@
> // the object is destroyed.
> class PgTransaction : public PgDatabase {
> public:
> - PgTransaction(const char* conninfo); // use reasonable & environment defaults
> + explicit PgTransaction(const char conninfo[]); // use reasonable & environment defaults
> // connect to the database with given environment and database name
> - // PgTransaction(const PgConnection&);
> + // explicit PgTransaction(const PgConnection&);
> ~PgTransaction(); // close connection and clean up
>
> protected:
> @@ -46,9 +46,11 @@
> ExecStatusType EndTransaction();
>
> protected:
> - PgTransaction() : PgDatabase() {} // Do not connect
> + PgTransaction() : PgDatabase(), pgCommitted(true) {} // Do not connect
>
> private:
> + bool pgCommitted;
> +
> // We don't support copying of PgTransaction objects,
> // so make copy constructor and assignment op private.
> PgTransaction(const PgTransaction&);
>
>
>
> Jeroen
>
>

--
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