testlibpq2.c

This is testlibpq2.c in view mode; [Download] [Up]

/*
 * testlibpq2.c
 * 	Test of the asynchronous notification interface
 *
   populate a database with the following:

CREATE TABLE TBL1 (i int4);

CREATE TABLE TBL2 (i int4);

CREATE RULE r1 AS ON INSERT TO TBL1 DO [INSERT INTO TBL2 values (new.i); NOTIFY TBL2];

 * Then start up this program
 * After the program has begun, do

INSERT INTO TBL1 values (10);

 *
 *
 */
#include <stdio.h>
#include "libpq-fe.h"

void exit_nicely(PGconn* conn)
{
  PQfinish(conn);
  exit(1);
}

main()
{
  char *pghost, *pgport, *pgoptions, *pgtty;
  char* dbName;
  int nFields;
  int i,j;

  PGconn* conn;
  PGresult* res;
  PGnotify* notify;

  /* begin, by setting the parameters for a backend connection
     if the parameters are null, then the system will try to use
     reasonable defaults by looking up environment variables 
     or, failing that, using hardwired constants */
  pghost = NULL;  /* host name of the backend server */
  pgport = NULL;  /* port of the backend server */
  pgoptions = NULL; /* special options to start up the backend server */
  pgtty = NULL;     /* debugging tty for the backend server */
  dbName = getenv("USER"); /* change this to the name of your test database*/

  /* make a connection to the database */
  conn = PQsetdb(pghost, pgport, pgoptions, pgtty, dbName);

  /* check to see that the backend connection was successfully made */
  if (PQstatus(conn) == CONNECTION_BAD) {
    fprintf(stderr,"Connection to database '%s' failed.\n", dbName);
    fprintf(stderr,"%s",PQerrorMessage(conn));
    exit_nicely(conn);
  }

  res = PQexec(conn, "LISTEN TBL2");
  if (PQresultStatus(res) != PGRES_COMMAND_OK) {
    fprintf(stderr,"LISTEN command failed\n");
    PQclear(res);
    exit_nicely(conn);
  }
  /* should PQclear PGresult whenever it is no longer needed to avoid
     memory leaks */
  PQclear(res); 

  while (1) {
      /* async notification only come back as a result of a query*/
      /* we can send empty queries */
      res = PQexec(conn, " ");
/*      printf("res->status = %s\n", pgresStatus[PQresultStatus(res)]); */
      /* check for asynchronous returns */
      notify = PQnotifies(conn);
      if (notify) {
	  fprintf(stderr,
		  "ASYNC NOTIFY of '%s' from backend pid '%d' received\n",
		  notify->relname, notify->be_pid);
	  free(notify);
	  break;
      }
      PQclear(res);
  }
      
  /* close the connection to the database and cleanup */
  PQfinish(conn);

}

These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.