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Bring the libpq example programs into the 21st century.
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8 files changed

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-602
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8 files changed

+574
-602
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‎doc/src/sgml/libpq.sgml

Lines changed: 356 additions & 358 deletions
Large diffs are not rendered by default.

‎src/test/examples/Makefile

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,10 +7,9 @@ top_builddir = ../../..
77
include $(top_builddir)/src/Makefile.global
88

99
override CPPFLAGS := -I$(libpq_srcdir) $(CPPFLAGS)
10-
LIBS += $(libpq)
10+
LDFLAGS += $(libpq)
1111

1212

13-
# PROGS= testlibpq0 testlibpq1 testlibpq2 testlibpq3 testlibpq4 testlo
1413
PROGS = testlibpq testlibpq2 testlibpq3 testlibpq4 testlo
1514

1615
all: $(PROGS)

‎src/test/examples/testlibpq.c

Lines changed: 35 additions & 49 deletions
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,10 @@
11
/*
22
* testlibpq.c
3-
* Test the C version of LIBPQ, the POSTGRES frontend library.
4-
*
53
*
4+
* Test the C version of LIBPQ, the POSTGRES frontend library.
65
*/
76
#include <stdio.h>
7+
#include <stdlib.h>
88
#include "libpq-fe.h"
99

1010
static void
@@ -15,76 +15,66 @@ exit_nicely(PGconn *conn)
1515
}
1616

1717
int
18-
main()
18+
main(int argc, char **argv)
1919
{
20-
char *pghost,
21-
*pgport,
22-
*pgoptions,
23-
*pgtty;
24-
char *dbName;
20+
const char *conninfo;
21+
PGconn *conn;
22+
PGresult *res;
2523
int nFields;
2624
int i,
2725
j;
2826

29-
#ifdef DEBUG
30-
FILE *debug;
31-
#endif /* DEBUG */
32-
33-
PGconn *conn;
34-
PGresult *res;
35-
3627
/*
37-
* begin, by setting the parameters for a backend connection if the
38-
* parameters are null, then the system will try to use reasonable
39-
* defaults by looking up environment variables or, failing that,
40-
* using hardwired constants
28+
* If the user supplies a parameter on the command line, use it as
29+
* the conninfo string; otherwise default to setting dbname=template1
30+
* and using environment variables or defaults for all other connection
31+
* parameters.
4132
*/
42-
pghost = NULL; /* host name of the backend server */
43-
pgport = NULL; /* port of the backend server */
44-
pgoptions = NULL; /* special options to start up the backend
45-
* server */
46-
pgtty = NULL; /* debugging tty for the backend server */
47-
dbName = "template1";
48-
49-
/* make a connection to the database */
50-
conn = PQsetdb(pghost, pgport, pgoptions, pgtty, dbName);
51-
52-
/* check to see that the backend connection was successfully made */
53-
if (PQstatus(conn) == CONNECTION_BAD)
33+
if (argc > 1)
34+
conninfo = argv[1];
35+
else
36+
conninfo = "dbname = template1";
37+
38+
/* Make a connection to the database */
39+
conn = PQconnectdb(conninfo);
40+
41+
/* Check to see that the backend connection was successfully made */
42+
if (PQstatus(conn) != CONNECTION_OK)
5443
{
55-
fprintf(stderr, "Connection to database '%s' failed.\n", dbName);
44+
fprintf(stderr, "Connection to database '%s' failed.\n", PQdb(conn));
5645
fprintf(stderr, "%s", PQerrorMessage(conn));
5746
exit_nicely(conn);
5847
}
5948

60-
#ifdef DEBUG
61-
debug = fopen("/tmp/trace.out", "w");
62-
PQtrace(conn, debug);
63-
#endif /* DEBUG */
49+
/*
50+
* Our test case here involves using a cursor, for which we must be
51+
* inside a transaction block. We could do the whole thing with a
52+
* single PQexec() of "select * from pg_database", but that's too
53+
* trivial to make a good example.
54+
*/
6455

65-
/* start a transaction block */
56+
/* Start a transaction block */
6657
res = PQexec(conn, "BEGIN");
6758
if (PQresultStatus(res) != PGRES_COMMAND_OK)
6859
{
69-
fprintf(stderr, "BEGIN command failed\n");
60+
fprintf(stderr, "BEGIN command failed: %s", PQerrorMessage(conn));
7061
PQclear(res);
7162
exit_nicely(conn);
7263
}
7364

7465
/*
75-
* should PQclear PGresult whenever it is no longer needed to avoid
66+
* Should PQclear PGresult whenever it is no longer needed to avoid
7667
* memory leaks
7768
*/
7869
PQclear(res);
7970

8071
/*
81-
* fetch instances from the pg_database, the system catalog of
82-
* databases
72+
* Fetch rows from pg_database, the system catalog of databases
8373
*/
8474
res = PQexec(conn, "DECLARE myportal CURSOR FOR select * from pg_database");
8575
if (PQresultStatus(res) != PGRES_COMMAND_OK)
8676
{
87-
fprintf(stderr, "DECLARE CURSOR command failed\n");
77+
fprintf(stderr, "DECLARE CURSOR failed: %s", PQerrorMessage(conn));
8878
PQclear(res);
8979
exit_nicely(conn);
9080
}
@@ -93,7 +83,7 @@ main()
9383
res = PQexec(conn, "FETCH ALL in myportal");
9484
if (PQresultStatus(res) != PGRES_TUPLES_OK)
9585
{
96-
fprintf(stderr, "FETCH ALL command didn't return tuples properly\n");
86+
fprintf(stderr, "FETCH ALL failed: %s", PQerrorMessage(conn));
9787
PQclear(res);
9888
exit_nicely(conn);
9989
}
@@ -104,7 +94,7 @@ main()
10494
printf("%-15s", PQfname(res, i));
10595
printf("\n\n");
10696

107-
/* next, print out the instances */
97+
/* next, print out the rows */
10898
for (i = 0; i < PQntuples(res); i++)
10999
{
110100
for (j = 0; j < nFields; j++)
@@ -114,7 +104,7 @@ main()
114104

115105
PQclear(res);
116106

117-
/* close the portal */
107+
/* close the portal ... we don't bother to check for errors ... */
118108
res = PQexec(conn, "CLOSE myportal");
119109
PQclear(res);
120110

@@ -125,9 +115,5 @@ main()
125115
/* close the connection to the database and cleanup */
126116
PQfinish(conn);
127117

128-
#ifdef DEBUG
129-
fclose(debug);
130-
#endif /* DEBUG */
131-
132118
return 0;
133119
}

‎src/test/examples/testlibpq2.c

Lines changed: 75 additions & 56 deletions
Original file line numberDiff line numberDiff line change
@@ -2,24 +2,30 @@
22
* testlibpq2.c
33
* Test of the asynchronous notification interface
44
*
5-
populate a database with the following:
6-
7-
CREATE TABLE TBL1 (i int4);
8-
9-
CREATE TABLE TBL2 (i int4);
10-
11-
CREATE RULE r1 AS ON INSERT TO TBL1 DO [INSERT INTO TBL2 values (new.i); NOTIFY TBL2];
12-
13-
* Then start up this program
14-
* After the program has begun, do
15-
16-
INSERT INTO TBL1 values (10);
17-
5+
* Start this program, then from psql in another window do
6+
* NOTIFY TBL2;
7+
* Repeat four times to get this program to exit.
8+
*
9+
* Or, if you want to get fancy, try this:
10+
* populate a database with the following commands
11+
* (provided in src/test/examples/testlibpq2.sql):
1812
*
13+
* CREATE TABLE TBL1 (i int4);
1914
*
15+
* CREATE TABLE TBL2 (i int4);
16+
*
17+
* CREATE RULE r1 AS ON INSERT TO TBL1 DO
18+
* (INSERT INTO TBL2 VALUES (new.i); NOTIFY TBL2);
19+
*
20+
* and do this four times:
21+
*
22+
* INSERT INTO TBL1 VALUES (10);
2023
*/
2124
#include <stdio.h>
2225
#include <stdlib.h>
26+
#include <string.h>
27+
#include <errno.h>
28+
#include <sys/time.h>
2329
#include "libpq-fe.h"
2430

2531
static void
@@ -30,51 +36,43 @@ exit_nicely(PGconn *conn)
3036
}
3137

3238
int
33-
main()
39+
main(int argc, char **argv)
3440
{
35-
char *pghost,
36-
*pgport,
37-
*pgoptions,
38-
*pgtty;
39-
char *dbName;
40-
41-
/*
42-
* int nFields; int i, j;
43-
*/
44-
41+
const char *conninfo;
4542
PGconn *conn;
4643
PGresult *res;
4744
PGnotify *notify;
45+
int nnotifies;
4846

4947
/*
50-
* begin, by setting the parameters for a backend connection if the
51-
* parameters are null, then the system will try to use reasonable
52-
* defaults by looking up environment variables or, failing that,
53-
* using hardwired constants
48+
* If the user supplies a parameter on the command line, use it as
49+
* the conninfo string; otherwise default to setting dbname=template1
50+
* and using environment variables or defaults for all other connection
51+
* parameters.
5452
*/
55-
pghost = NULL; /* host name of the backend server */
56-
pgport = NULL; /* port of the backend server */
57-
pgoptions = NULL; /* special options to start up the backend
58-
* server */
59-
pgtty = NULL; /* debugging tty for the backend server */
60-
dbName = getenv("USER"); /* change this to the name of your test
61-
* database */
62-
63-
/* make a connection to the database */
64-
conn = PQsetdb(pghost, pgport, pgoptions, pgtty, dbName);
65-
66-
/* check to see that the backend connection was successfully made */
67-
if (PQstatus(conn) == CONNECTION_BAD)
53+
if (argc > 1)
54+
conninfo = argv[1];
55+
else
56+
conninfo = "dbname = template1";
57+
58+
/* Make a connection to the database */
59+
conn = PQconnectdb(conninfo);
60+
61+
/* Check to see that the backend connection was successfully made */
62+
if (PQstatus(conn) != CONNECTION_OK)
6863
{
69-
fprintf(stderr, "Connection to database '%s' failed.\n", dbName);
64+
fprintf(stderr, "Connection to database '%s' failed.\n", PQdb(conn));
7065
fprintf(stderr, "%s", PQerrorMessage(conn));
7166
exit_nicely(conn);
7267
}
7368

69+
/*
70+
* Issue LISTEN command to enable notifications from the rule's NOTIFY.
71+
*/
7472
res = PQexec(conn, "LISTEN TBL2");
7573
if (PQresultStatus(res) != PGRES_COMMAND_OK)
7674
{
77-
fprintf(stderr, "LISTEN command failed\n");
75+
fprintf(stderr, "LISTEN command failed: %s", PQerrorMessage(conn));
7876
PQclear(res);
7977
exit_nicely(conn);
8078
}
@@ -85,27 +83,48 @@ main()
8583
*/
8684
PQclear(res);
8785

88-
while (1)
86+
/* Quit after four notifies are received. */
87+
nnotifies = 0;
88+
while (nnotifies < 4)
8989
{
90-
/* async notification only come back as a result of a query */
91-
/* we can send empty queries */
92-
res = PQexec(conn, " ");
93-
/* printf("res->status = %s\n", PQresStatus(PQresultStatus(res))); */
94-
/* check for asynchronous returns */
95-
notify = PQnotifies(conn);
96-
if (notify)
90+
/*
91+
* Sleep until something happens on the connection. We use select(2)
92+
* to wait for input, but you could also use poll() or similar
93+
* facilities.
94+
*/
95+
int sock;
96+
fd_set input_mask;
97+
98+
sock = PQsocket(conn);
99+
100+
if (sock < 0)
101+
break; /* shouldn't happen */
102+
103+
FD_ZERO(&input_mask);
104+
FD_SET(sock, &input_mask);
105+
106+
if (select(sock + 1, &input_mask, NULL, NULL, NULL) < 0)
107+
{
108+
fprintf(stderr, "select() failed: %s\n", strerror(errno));
109+
exit_nicely(conn);
110+
}
111+
112+
/* Now check for input */
113+
PQconsumeInput(conn);
114+
while ((notify = PQnotifies(conn)) != NULL)
97115
{
98116
fprintf(stderr,
99-
"ASYNC NOTIFY of '%s' from backend pid '%d' received\n",
117+
"ASYNC NOTIFY of '%s' received from backend pid %d\n",
100118
notify->relname, notify->be_pid);
101119
PQfreemem(notify);
102-
break;
120+
nnotifies++;
103121
}
104-
PQclear(res);
105122
}
106123

124+
fprintf(stderr, "Done.\n");
125+
107126
/* close the connection to the database and cleanup */
108127
PQfinish(conn);
109-
return 0; /* Though PQfinish(conn1) has called
110-
* exit(1) */
128+
129+
return 0;
111130
}

‎src/test/examples/testlibpq2.sql

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2,4 +2,5 @@ CREATE TABLE TBL1 (i int4);
22

33
CREATE TABLE TBL2 (i int4);
44

5-
CREATE RULE r1 AS ON INSERT TO TBL1 DO [INSERT INTO TBL2 values (new.i); NOTIFY TBL2];
5+
CREATE RULE r1 AS ON INSERT TO TBL1 DO
6+
(INSERT INTO TBL2 VALUES (new.i); NOTIFY TBL2);

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