pg_ctl: Add idempotent option

This changes the behavior of the start and stop actions to exit
successfully if the server was already started or stopped.

This changes the default behavior of the start action:  Before, if the
server was already running, it would print a message and succeed.  Now,
that situation will result in an error.  When running in idempotent
mode, no message is printed and pg_ctl exits successfully.

It was considered to just make the idempotent behavior the default and
only option, but pg_upgrade needs the old behavior.

diff --git a/contrib/start-scripts/linux b/contrib/start-scripts/linux
index b950cf512c3c519c1813f69af98a7a0ce7422769..03c6e503bc609d01b59cf9d2aeaa2658f48c703b 100644 (file)
--- 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 3107514901ce96463261596931b1721534ca9089..549730da6f9edd5aefb67973c5925aa1725d1cb9 100644 (file)
--- a/doc/src/sgml/ref/pg_ctl-ref.sgml
+++ b/doc/src/sgml/ref/pg_ctl-ref.sgml
@@ -39,6 +39,7 @@ PostgreSQL documentation
    <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 @@ PostgreSQL documentation
        <arg choice="plain"><option>i[mmediate]</option></arg>
      </group>
    </arg>
+   <arg choice="opt"><option>-I</option></arg>
   </cmdsynopsis>
 
   <cmdsynopsis>
@@ -270,6 +272,25 @@ PostgreSQL documentation
       </listitem>
      </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>

diff --git a/src/bin/pg_ctl/pg_ctl.c b/src/bin/pg_ctl/pg_ctl.c
index 537d173e893b0a56d99e0015dd7764dc7c76c5af..a4e7922d687e2c67c5ed0898e3319ecb18c107c0 100644 (file)
--- a/src/bin/pg_ctl/pg_ctl.c
+++ b/src/bin/pg_ctl/pg_ctl.c
@@ -85,6 +85,7 @@ static char *pg_config = NULL;
 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? */
@@ -773,9 +774,15 @@ do_start(void)
    {
        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();
@@ -859,6 +866,8 @@ do_stop(void)
 
    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);
@@ -1763,9 +1772,9 @@ do_help(void)
    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);
@@ -1798,6 +1807,8 @@ do_help(void)
    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"));
 
@@ -1980,6 +1991,7 @@ main(int argc, char **argv)
        {"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}
    };
 
@@ -2045,7 +2057,7 @@ main(int argc, char **argv)
    /* 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)
            {
@@ -2071,6 +2083,9 @@ main(int argc, char **argv)
                                 pgdata_D);
                        break;
                    }
+               case 'I':
+                   idempotent = true;
+                   break;
                case 'l':
                    log_file = pg_strdup(optarg);
                    break;