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138 lines
2.9 KiB
C
138 lines
2.9 KiB
C
/*
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* src/test/examples/testlibpq2.c
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*
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*
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* testlibpq2.c
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* Test of the asynchronous notification interface
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*
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* Start this program, then from psql in another window do
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* NOTIFY TBL2;
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* Repeat four times to get this program to exit.
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*
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* Or, if you want to get fancy, try this:
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* populate a database with the following commands
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* (provided in src/test/examples/testlibpq2.sql):
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*
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* CREATE TABLE TBL1 (i int4);
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*
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* CREATE TABLE TBL2 (i int4);
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*
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* CREATE RULE r1 AS ON INSERT TO TBL1 DO
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* (INSERT INTO TBL2 VALUES (new.i); NOTIFY TBL2);
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*
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* and do this four times:
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*
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* INSERT INTO TBL1 VALUES (10);
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*/
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#ifdef WIN32
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#include <windows.h>
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include "libpq-fe.h"
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static void
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exit_nicely(PGconn *conn)
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{
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PQfinish(conn);
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exit(1);
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}
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int
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main(int argc, char **argv)
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{
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const char *conninfo;
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PGconn *conn;
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PGresult *res;
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PGnotify *notify;
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int nnotifies;
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/*
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* If the user supplies a parameter on the command line, use it as the
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* conninfo string; otherwise default to setting dbname=postgres and using
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* environment variables or defaults for all other connection parameters.
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*/
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if (argc > 1)
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conninfo = argv[1];
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else
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conninfo = "dbname = postgres";
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/* Make a connection to the database */
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conn = PQconnectdb(conninfo);
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/* Check to see that the backend connection was successfully made */
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if (PQstatus(conn) != CONNECTION_OK)
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{
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fprintf(stderr, "Connection to database failed: %s",
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PQerrorMessage(conn));
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exit_nicely(conn);
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}
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/*
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* Issue LISTEN command to enable notifications from the rule's NOTIFY.
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*/
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res = PQexec(conn, "LISTEN TBL2");
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if (PQresultStatus(res) != PGRES_COMMAND_OK)
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{
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fprintf(stderr, "LISTEN command failed: %s", PQerrorMessage(conn));
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PQclear(res);
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exit_nicely(conn);
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}
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/*
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* should PQclear PGresult whenever it is no longer needed to avoid memory
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* leaks
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*/
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PQclear(res);
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/* Quit after four notifies are received. */
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nnotifies = 0;
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while (nnotifies < 4)
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{
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/*
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* Sleep until something happens on the connection. We use select(2)
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* to wait for input, but you could also use poll() or similar
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* facilities.
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*/
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int sock;
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fd_set input_mask;
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sock = PQsocket(conn);
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if (sock < 0)
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break; /* shouldn't happen */
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FD_ZERO(&input_mask);
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FD_SET(sock, &input_mask);
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if (select(sock + 1, &input_mask, NULL, NULL, NULL) < 0)
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{
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fprintf(stderr, "select() failed: %s\n", strerror(errno));
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exit_nicely(conn);
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}
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/* Now check for input */
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PQconsumeInput(conn);
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while ((notify = PQnotifies(conn)) != NULL)
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{
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fprintf(stderr,
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"ASYNC NOTIFY of '%s' received from backend PID %d\n",
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notify->relname, notify->be_pid);
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PQfreemem(notify);
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nnotifies++;
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}
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}
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fprintf(stderr, "Done.\n");
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/* close the connection to the database and cleanup */
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PQfinish(conn);
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return 0;
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}
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