88 *
99 *
1010 * IDENTIFICATION
11- * $Header: /cvsroot/pgsql/src/backend/utils/adt/regexp.c,v 1.39 2002/06/11 15:41:37 thomas Exp $
11+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/regexp.c,v 1.40 2002/06/15 02:49:47 thomas Exp $
1212 *
1313 *Alistair Crooks added the code for the regex caching
1414 *agc - cached the regular expressions used - there's a good chance
@@ -53,7 +53,7 @@ struct cached_re_str
5353static int rec = 0 ;/* # of cached re's */
5454static struct cached_re_str rev [MAX_CACHED_RES ];/* cached re's */
5555static unsigned long lru ;/* system lru tag */
56- static int pg_lastre = 0 ;
56+ static int pg_lastrec = 0 ;
5757
5858/* attempt to compile `re' as an re, then match it against text */
5959/* cflags - flag to regcomp indicates case sensitivity */
@@ -70,43 +70,46 @@ RE_compile_and_execute(text *text_re, char *text, int cflags,
7070re = DatumGetCString (DirectFunctionCall1 (textout ,
7171PointerGetDatum (text_re )));
7272
73- if ((i = pg_lastre )< rec )
73+ /* Find a previously compiled regular expression.
74+ * Run the cache as a ring buffer, starting the search
75+ * from the previous match if any.
76+ */
77+ i = pg_lastrec ;
78+ while (i < rec )
7479{
75- if (rev [i ].cre_s )
80+ if (rev [i ].cre_s != NULL )
7681{
7782if (strcmp (rev [i ].cre_s ,re )== 0 &&
7883rev [i ].cre_type == cflags )
7984{
85+ pg_lastrec = i ;
8086rev [i ].cre_lru = ++ lru ;
8187pfree (re );
8288return (pg_regexec (& rev [i ].cre_re ,
8389text ,nmatch ,
8490pmatch ,0 )== 0 );
8591}
8692}
87- }
88-
89- /* find a previously compiled regular expression */
90- for (i = 0 ;i < rec ;i ++ )
91- {
92- if (i == pg_lastre )continue ;
93+ i ++ ;
9394
94- if (rev [i ].cre_s )
95+ /* If we were not at the first slot to start,
96+ * then think about wrapping if necessary.
97+ */
98+ if (pg_lastrec != 0 )
9599{
96- if (strcmp (rev [i ].cre_s ,re )== 0 &&
97- rev [i ].cre_type == cflags )
100+ if (i >=rec )
98101{
99- rev [ i ]. cre_lru = ++ lru ;
100- pfree ( re );
101- return ( pg_regexec ( & rev [ i ]. cre_re ,
102- text , nmatch ,
103- pmatch , 0 ) == 0 ) ;
102+ i = 0 ;
103+ }
104+ else if ( i == pg_lastrec )
105+ {
106+ break ;
104107}
105108}
106109}
107110
108111/* we didn't find it - make room in the cache for it */
109- if (rec = =MAX_CACHED_RES )
112+ if (rec > =MAX_CACHED_RES )
110113{
111114/* cache is full - find the oldest entry */
112115for (oldest = 0 ,i = 1 ;i < rec ;i ++ )
@@ -116,13 +119,16 @@ RE_compile_and_execute(text *text_re, char *text, int cflags,
116119}
117120}
118121else
122+ {
119123oldest = rec ++ ;
124+ }
120125
121126/* if there was an old re, then de-allocate the space it used */
122127if (rev [oldest ].cre_s != (char * )NULL )
123128{
124129for (lru = i = 0 ;i < rec ;i ++ )
125130{
131+ /* downweight all of the other cached entries */
126132rev [i ].cre_lru = (rev [i ].cre_lru - rev [oldest ].cre_lru ) /2 ;
127133if (rev [i ].cre_lru > lru )
128134lru = rev [i ].cre_lru ;
@@ -141,6 +147,7 @@ RE_compile_and_execute(text *text_re, char *text, int cflags,
141147regcomp_result = pg_regcomp (& rev [oldest ].cre_re ,re ,cflags );
142148if (regcomp_result == 0 )
143149{
150+ pg_lastrec = oldest ;
144151/*
145152 * use malloc/free for the cre_s field because the storage has to
146153 * persist across transactions
@@ -311,7 +318,6 @@ textregexsubstr(PG_FUNCTION_ARGS)
311318{
312319text * s = PG_GETARG_TEXT_P (0 );
313320text * p = PG_GETARG_TEXT_P (1 );
314- text * result ;
315321char * sterm ;
316322int len ;
317323bool match ;
@@ -339,16 +345,6 @@ textregexsubstr(PG_FUNCTION_ARGS)
339345Int32GetDatum (pmatch .rm_so + 1 ),
340346Int32GetDatum (pmatch .rm_eo - pmatch .rm_so )));
341347}
342- #if 0
343- /* otherwise, return a zero-length string */
344- else
345- {
346- result = palloc (VARHDRSZ );
347- VARATT_SIZEP (result )= VARHDRSZ ;
348- PG_RETURN_TEXT_P (result );
349- }
350- #endif
351348
352- /* not reached */
353349PG_RETURN_NULL ();
354350}
