Attached patch gets rid of the global timezone in the following steps:

* Changes the APIs to the timezone functions to take a pg_tz pointer as
an argument, representing the timezone to use for the selected
operation.

* Adds a global_timezone variable that represents the current timezone
in the backend as set by SET TIMEZONE (or guc, or env, etc).

* Implements a hash-table cache of loaded tables, so we don't have to
read and parse the TZ file everytime we change a timezone. While not
necesasry now (we don't change timezones very often), I beleive this
will be necessary (or at least good) when "multiple timezones in the
same query" is eventually implemented. And code-wise, this was the time
to do it.


There are no user-visible changes at this time. Implementing the
"multiple zones in one query" is a later step...

This also gets rid of some of the cruft needed to "back out a timezone
change", since we previously couldn't check a timezone unless it was
activated first.

Passes regression tests on win32, linux (slackware 10) and solaris x86.

Magnus Hagander

1 files changed, 43 insertions, 1 deletions

diff --git a/src/timezone/pgtz.h b/src/timezone/pgtz.h
index 6c05198aed7..e325dec4832 100644
--- a/src/timezone/pgtz.h
+++ b/src/timezone/pgtz.h
@@ -9,15 +9,57 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/timezone/pgtz.h,v 1.10 2004/12/31 22:03:59 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/timezone/pgtz.h,v 1.11 2005/04/19 03:13:59 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
 #ifndef _PGTZ_H
 #define _PGTZ_H
 
+#include "tzfile.h"
+
 #define TZ_STRLEN_MAX 255
 
 extern char *pg_TZDIR(void);
 
+#define BIGGEST(a, b)	(((a) > (b)) ? (a) : (b))
+
+struct ttinfo
+{								/* time type information */
+	long		tt_gmtoff;		/* UTC offset in seconds */
+	int			tt_isdst;		/* used to set tm_isdst */
+	int			tt_abbrind;		/* abbreviation list index */
+	int			tt_ttisstd;		/* TRUE if transition is std time */
+	int			tt_ttisgmt;		/* TRUE if transition is UTC */
+};
+
+struct lsinfo
+{								/* leap second information */
+	pg_time_t	ls_trans;		/* transition time */
+	long		ls_corr;		/* correction to apply */
+};
+
+struct state
+{
+	int			leapcnt;
+	int			timecnt;
+	int			typecnt;
+	int			charcnt;
+	pg_time_t	ats[TZ_MAX_TIMES];
+	unsigned char types[TZ_MAX_TIMES];
+	struct ttinfo ttis[TZ_MAX_TYPES];
+	char		chars[BIGGEST(BIGGEST(TZ_MAX_CHARS + 1, 3 /* sizeof gmt */),
+										  (2 * (TZ_STRLEN_MAX + 1)))];
+	struct lsinfo lsis[TZ_MAX_LEAPS];
+};
+
+
+struct pg_tz {
+	char TZname[TZ_STRLEN_MAX + 1];
+	struct state state;
+};
+
+int	tzload(const char *name, struct state * sp);
+int	tzparse(const char *name, struct state * sp, int lastditch);
+
 #endif   /* _PGTZ_H */