Refactor code in pgsql_src for server monitoring

Michael Paquier · Michael Paquier · commit ebe21663797d · 2013-12-12T23:54:52.000+09:00
Most of those things are taken from pg_ctl.c, but were somewhat not
really in a place corresponding to their role.
diff --git a/Makefile b/Makefile
@@ -10,10 +10,10 @@ SRCS = \
 	pg_rman.c \
 	restore.c \
 	show.c \
+	status.c \
 	util.c \
 	validate.c \
 	xlog.c \
-	pgsql_src/pg_ctl.c \
 	pgut/pgut.c \
 	pgut/pgut-port.c
 OBJS = $(SRCS:.c=.o)
diff --git a/pgsql_src/COPYRIGHT.pgsql_src b/pgsql_src/COPYRIGHT.pgsql_src
diff --git a/status.c b/status.c
@@ -1,10 +1,10 @@
 /*-------------------------------------------------------------------------
  *
- * pg_ctl --- start/stops/restarts the PostgreSQL server
+ * status.c
  *
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/bin/pg_ctl/pg_ctl.c,v 1.111 2009/06/11 14:49:07 momjian Exp $
+ * Monitor status of a PostgreSQL server.
  *
  *-------------------------------------------------------------------------
  */
@@ -24,36 +24,51 @@ typedef long pgpid_t;
 static pgpid_t get_pgpid(void);
 static bool postmaster_is_alive(pid_t pid);
 
-static char pid_file[MAXPGPATH];
-
-
+/*
+ * get_pgpid
+ *
+ * Get PID of postmaster, by scanning postmaster.pid.
+ */
 static pgpid_t
 get_pgpid(void)
 {
 	FILE	   *pidf;
 	long		pid;
+	char		pid_file[MAXPGPATH];
 
 	snprintf(pid_file, lengthof(pid_file), "%s/postmaster.pid", pgdata);
+
 	pidf = fopen(pid_file, "r");
 	if (pidf == NULL)
 	{
 		/* No pid file, not an error on startup */
 		if (errno == ENOENT)
 			return 0;
 		else
+		{
 			elog(ERROR_SYSTEM, _("could not open PID file \"%s\": %s\n"),
-						 pid_file, strerror(errno));
+				 pid_file, strerror(errno));
+		}
+		if (fscanf(pidf, "%ld", &pid) != 1)
+		{
+			/* Is the file empty? */
+			if (ftell(pidf) == 0 && feof(pidf))
+				elog(ERROR_SYSTEM, _("the PID file \"%s\" is empty\n"),
+					 pid_file);
+			else
+				elog(ERROR_SYSTEM, _("invalid data in PID file \"%s\"\n"),
+					 pid_file);
+		}
 	}
-	if (fscanf(pidf, "%ld", &pid) != 1)
-		elog(ERROR_PID_BROKEN, _("invalid data in PID file \"%s\"\n"), pid_file);
 	fclose(pidf);
 	return (pgpid_t) pid;
 }
 
 /*
- *	utility routines
+ * postmaster_is_alive
+ *
+ * Check whether postmaster is alive or not.
  */
-
 static bool
 postmaster_is_alive(pid_t pid)
 {
@@ -79,27 +94,25 @@ postmaster_is_alive(pid_t pid)
 }
 
 /*
- * original is do_status() in src/bin/pg_ctl/pg_ctl.c
- * changes are:
- *   renamed from do_status() from do_status().
- *   return true if PG server is running.
- *   don't print any message.
- *   don't print postopts file.
- *   log with elog() in pgut library.
+ * is_pg_running
+ *
+ *
  */
 bool
 is_pg_running(void)
 {
 	pgpid_t		pid;
 
 	pid = get_pgpid();
-	if (pid == 0)				/* 0 means no pid file */
+
+	/* 0 means no pid file */
+	if (pid == 0)
 		return false;
 
-	if (pid < 0)			/* standalone backend */
+	/* Case of a standalone backend */
+	if (pid < 0)
 		pid = -pid;
 
-
+	/* Check if postmaster is alive */
 	return postmaster_is_alive((pid_t) pid);
 }
-
