Re: Where I find examples of pqtrace?

On Sat, May 06, 2006 at 12:08:32AM -0300, Marcelo Fabiano da Silveira wrote:
> I Have some questions of use PQtrace in Windows' systens....
>
> 1- The implementation of PQtrace, is possible ONLY with non bloking
> connections ???
> 2- Please, I need same samples of implementation of PQtrace.

PQtrace(PGconn *conn, FILE *fp) enables logging of sent/received data
(appears on PGconn *conn), to the file pointed by FILE *fp. It achieves
this by making simple fprintf(fp, ...) calls using the file pointed by fp.
(I hope above explanation also answers to your 1st question.)

Here's a simple use case:

PGconn *conn = PQconnectdb("...");
FILE *fp;

fp = fopen(...);
if (!fp)
{
/*
* It's programmer's responsibility to take care of the file
* pointer. Moreover, a blocking socket (on the FILE *fp) will
* cause fprintf(fp, ...) calls to block too, which is an undesired
* behaviour for an API. So you should take the care of consistency
* of this part too.
*/
}

/*
* File is opened with success and we're sure it won't block for
* writing.
*/
PQtrace(conn, fp);

...

/*
* We won't need a connection anymore. Thus, droping connection and its
* tracing.
*/
PQuntrace(conn);
PQfinish(conn);

Regards.