On Mon, 2013-01-14 at 06:37 -0500, Peter Eisentraut wrote:
> Here is a patch to add an option -I/--idempotent to pg_ctl, the result
> of which is that pg_ctl doesn't error on start or stop if the server is
> already running or already stopped.
So apparently, pg_upgrade needs the existing behavior, so making the
idempotent option the only behavior won't work. Therefore, I think this
patch is still useful as originally presented. I've made one change
that pg_ctl won't print any messages if the -I option is used and the
server is already started/stopped.
diff --git a/contrib/start-scripts/linux b/contrib/start-scripts/linux
index b950cf5..03c6e50 100644
--- a/contrib/start-scripts/linux
+++ b/contrib/start-scripts/linux
@@ -84,17 +84,17 @@ case $1 in
echo -n "Starting PostgreSQL: "
test x"$OOM_SCORE_ADJ" != x && echo "$OOM_SCORE_ADJ" > /proc/self/oom_score_adj
test x"$OOM_ADJ" != x && echo "$OOM_ADJ" > /proc/self/oom_adj
- su - $PGUSER -c "$DAEMON -D '$PGDATA' &" >>$PGLOG 2>&1
+ su - $PGUSER -c "$DAEMON -I -D '$PGDATA' &" >>$PGLOG 2>&1
echo "ok"
;;
stop)
echo -n "Stopping PostgreSQL: "
- su - $PGUSER -c "$PGCTL stop -D '$PGDATA' -s -m fast"
+ su - $PGUSER -c "$PGCTL stop -I -D '$PGDATA' -s -m fast"
echo "ok"
;;
restart)
echo -n "Restarting PostgreSQL: "
- su - $PGUSER -c "$PGCTL stop -D '$PGDATA' -s -m fast -w"
+ su - $PGUSER -c "$PGCTL stop -I -D '$PGDATA' -s -m fast -w"
test x"$OOM_SCORE_ADJ" != x && echo "$OOM_SCORE_ADJ" > /proc/self/oom_score_adj
test x"$OOM_ADJ" != x && echo "$OOM_ADJ" > /proc/self/oom_adj
su - $PGUSER -c "$DAEMON -D '$PGDATA' &" >>$PGLOG 2>&1
diff --git a/doc/src/sgml/ref/pg_ctl-ref.sgml b/doc/src/sgml/ref/pg_ctl-ref.sgml
index 3107514..549730d 100644
--- a/doc/src/sgml/ref/pg_ctl-ref.sgml
+++ b/doc/src/sgml/ref/pg_ctl-ref.sgml
@@ -39,6 +39,7 @@
<arg choice="opt"><option>-o</option> <replaceable>options</replaceable></arg>
<arg choice="opt"><option>-p</option> <replaceable>path</replaceable></arg>
<arg choice="opt"><option>-c</option></arg>
+ <arg choice="opt"><option>-I</option></arg>
</cmdsynopsis>
<cmdsynopsis>
@@ -55,6 +56,7 @@
<arg choice="plain"><option>i[mmediate]</option></arg>
</group>
</arg>
+ <arg choice="opt"><option>-I</option></arg>
</cmdsynopsis>
<cmdsynopsis>
@@ -271,6 +273,25 @@ <title>Options</title>
</varlistentry>
<varlistentry>
+ <term><option>-I</option></term>
+ <term><option>--idempotent</option></term>
+ <listitem>
+ <para>
+ When used with the <literal>start</literal> or <literal>stop</literal>
+ actions, return exit code 0 if the server is already running or
+ stopped, respectively. Otherwise, an error is raised and a nonzero
+ exit code is returned in these cases.
+ </para>
+
+ <para>
+ This option is useful for System-V-style init scripts, which require
+ the <literal>start</literal> and <literal>stop</literal> actions to be
+ idempotent.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
<term><option>-l <replaceable class="parameter">filename</replaceable></option></term>
<term><option>--log <replaceable class="parameter">filename</replaceable></option></term>
<listitem>
diff --git a/src/bin/pg_ctl/pg_ctl.c b/src/bin/pg_ctl/pg_ctl.c
index 7d5e168..f6b92d1 100644
--- a/src/bin/pg_ctl/pg_ctl.c
+++ b/src/bin/pg_ctl/pg_ctl.c
@@ -86,6 +86,7 @@
static char *pgdata_opt = NULL;
static char *post_opts = NULL;
static const char *progname;
+static bool idempotent = false;
static char *log_file = NULL;
static char *exec_path = NULL;
static char *register_servicename = "PostgreSQL"; /* FIXME: + version ID? */
@@ -774,9 +775,15 @@
{
old_pid = get_pgpid();
if (old_pid != 0)
- write_stderr(_("%s: another server might be running; "
- "trying to start server anyway\n"),
- progname);
+ {
+ if (idempotent)
+ exit(0);
+ else
+ {
+ write_stderr(_("%s: another server might be running\n"), progname);
+ exit(1);
+ }
+ }
}
read_post_opts();
@@ -860,6 +867,8 @@
if (pid == 0) /* no pid file */
{
+ if (idempotent)
+ exit(0);
write_stderr(_("%s: PID file \"%s\" does not exist\n"), progname, pid_file);
write_stderr(_("Is server running?\n"));
exit(1);
@@ -1764,9 +1773,9 @@
printf(_("%s is a utility to initialize, start, stop, or control a PostgreSQL server.\n\n"), progname);
printf(_("Usage:\n"));
printf(_(" %s init[db] [-D DATADIR] [-s] [-o \"OPTIONS\"]\n"), progname);
- printf(_(" %s start [-w] [-t SECS] [-D DATADIR] [-s] [-l FILENAME] [-o \"OPTIONS\"]\n"), progname);
- printf(_(" %s stop [-W] [-t SECS] [-D DATADIR] [-s] [-m SHUTDOWN-MODE]\n"), progname);
- printf(_(" %s restart [-w] [-t SECS] [-D DATADIR] [-s] [-m SHUTDOWN-MODE]\n"
+ printf(_(" %s start [-w] [-t SECS] [-D DATADIR] [-s] [-I] [-l FILENAME] [-o \"OPTIONS\"]\n"), progname);
+ printf(_(" %s stop [-W] [-t SECS] [-D DATADIR] [-s] [-I] [-m SHUTDOWN-MODE]\n"), progname);
+ printf(_(" %s restart [-w] [-t SECS] [-D DATADIR] [-s] [-m SHUTDOWN-MODE]\n"
" [-o \"OPTIONS\"]\n"), progname);
printf(_(" %s reload [-D DATADIR] [-s]\n"), progname);
printf(_(" %s status [-D DATADIR]\n"), progname);
@@ -1799,6 +1808,8 @@
printf(_(" -o OPTIONS command line options to pass to postgres\n"
" (PostgreSQL server executable) or initdb\n"));
printf(_(" -p PATH-TO-POSTGRES normally not necessary\n"));
+ printf(_("\nOptions for start or stop:\n"));
+ printf(_(" -I, --idempotent don't error if server already running or stopped\n"));
printf(_("\nOptions for stop, restart, or promote:\n"));
printf(_(" -m, --mode=MODE MODE can be \"smart\", \"fast\", or \"immediate\"\n"));
@@ -1981,6 +1992,7 @@
{"silent", no_argument, NULL, 's'},
{"timeout", required_argument, NULL, 't'},
{"core-files", no_argument, NULL, 'c'},
+ {"idempotent", no_argument, NULL, 'I'},
{NULL, 0, NULL, 0}
};
@@ -2046,7 +2058,7 @@
/* process command-line options */
while (optind < argc)
{
- while ((c = getopt_long(argc, argv, "cD:l:m:N:o:p:P:sS:t:U:wW", long_options, &option_index)) != -1)
+ while ((c = getopt_long(argc, argv, "cD:Il:m:N:o:p:P:sS:t:U:wW", long_options, &option_index)) != -1)
{
switch (c)
{
@@ -2072,6 +2084,9 @@
pgdata_D);
break;
}
+ case 'I':
+ idempotent = true;
+ break;
case 'l':
log_file = pg_strdup(optarg);
break;
--
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