first commit for openGauss server

src/test/examples/testlibpq2.cpp

@@ -0,0 +1,127 @@
+/*
+ * src/test/examples/testlibpq2.c
+ *
+ *
+ * testlibpq2.c
+ *		Test of the asynchronous notification interface
+ *
+ * Start this program, then from psql in another window do
+ *	 NOTIFY TBL2;
+ * Repeat four times to get this program to exit.
+ *
+ * Or, if you want to get fancy, try this:
+ * populate a database with the following commands
+ * (provided in src/test/examples/testlibpq2.sql):
+ *
+ *	 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);
+ *
+ * and do this four times:
+ *
+ *	 INSERT INTO TBL1 VALUES (10);
+ */
+
+#ifdef WIN32
+#include <windows.h>
+#endif
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include "libpq-fe.h"
+
+static void exit_nicely(PGconn* conn)
+{
+    PQfinish(conn);
+    exit(1);
+}
+
+int main(int argc, char** argv)
+{
+    const char* conninfo = NULL;
+    PGconn* conn = NULL;
+    PGresult* res = NULL;
+    PGnotify* notify = NULL;
+    int nnotifies;
+
+    /*
+     * If the user supplies a parameter on the command line, use it as the
+     * conninfo string; otherwise default to setting dbname=postgres and using
+     * environment variables or defaults for all other connection parameters.
+     */
+    if (argc > 1)
+        conninfo = argv[1];
+    else
+        conninfo = "dbname = postgres";
+
+    /* Make a connection to the database */
+    conn = PQconnectdb(conninfo);
+
+    /* Check to see that the backend connection was successfully made */
+    if (PQstatus(conn) != CONNECTION_OK) {
+        fprintf(stderr, "Connection to database failed: %s", PQerrorMessage(conn));
+        exit_nicely(conn);
+    }
+
+    /*
+     * Issue LISTEN command to enable notifications from the rule's NOTIFY.
+     */
+    res = PQexec(conn, "LISTEN TBL2");
+    if (PQresultStatus(res) != PGRES_COMMAND_OK) {
+        fprintf(stderr, "LISTEN command failed: %s", PQerrorMessage(conn));
+        PQclear(res);
+        exit_nicely(conn);
+    }
+
+    /*
+     * should PQclear PGresult whenever it is no longer needed to avoid memory
+     * leaks
+     */
+    PQclear(res);
+
+    /* Quit after four notifies are received. */
+    nnotifies = 0;
+    while (nnotifies < 4) {
+        /*
+         * Sleep until something happens on the connection.  We use select(2)
+         * to wait for input, but you could also use poll() or similar
+         * facilities.
+         */
+        int sock;
+        fd_set input_mask;
+
+        sock = PQsocket(conn);
+
+        if (sock < 0)
+            break; /* shouldn't happen */
+
+        FD_ZERO(&input_mask);
+        FD_SET(sock, &input_mask);
+
+        if (select(sock + 1, &input_mask, NULL, NULL, NULL) < 0) {
+            fprintf(stderr, "select() failed: %s\n", strerror(errno));
+            exit_nicely(conn);
+        }
+
+        /* Now check for input */
+        PQconsumeInput(conn);
+        while ((notify = PQnotifies(conn)) != NULL) {
+            fprintf(stderr, "ASYNC NOTIFY of '%s' received from backend PID %d\n", notify->relname, notify->be_pid);
+            PQfreemem(notify);
+            nnotifies++;
+        }
+    }
+
+    fprintf(stderr, "Done.\n");
+
+    /* close the connection to the database and cleanup */
+    PQfinish(conn);
+
+    return 0;
+}