diff options
Diffstat (limited to 'src/backend/utils/adt/regexp.c')
| -rw-r--r-- | src/backend/utils/adt/regexp.c | 56 |
1 files changed, 26 insertions, 30 deletions
diff --git a/src/backend/utils/adt/regexp.c b/src/backend/utils/adt/regexp.c index 9afc58feee7..c8ef235f60f 100644 --- a/src/backend/utils/adt/regexp.c +++ b/src/backend/utils/adt/regexp.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/utils/adt/regexp.c,v 1.39 2002/06/11 15:41:37 thomas Exp $ + * $Header: /cvsroot/pgsql/src/backend/utils/adt/regexp.c,v 1.40 2002/06/15 02:49:47 thomas Exp $ * * Alistair Crooks added the code for the regex caching * agc - cached the regular expressions used - there's a good chance @@ -53,7 +53,7 @@ struct cached_re_str static int rec = 0; /* # of cached re's */ static struct cached_re_str rev[MAX_CACHED_RES]; /* cached re's */ static unsigned long lru; /* system lru tag */ -static int pg_lastre = 0; +static int pg_lastrec = 0; /* attempt to compile `re' as an re, then match it against text */ /* cflags - flag to regcomp indicates case sensitivity */ @@ -70,13 +70,19 @@ RE_compile_and_execute(text *text_re, char *text, int cflags, re = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(text_re))); - if ((i = pg_lastre) < rec) + /* Find a previously compiled regular expression. + * Run the cache as a ring buffer, starting the search + * from the previous match if any. + */ + i = pg_lastrec; + while (i < rec) { - if (rev[i].cre_s) + if (rev[i].cre_s != NULL) { if (strcmp(rev[i].cre_s, re) == 0 && rev[i].cre_type == cflags) { + pg_lastrec = i; rev[i].cre_lru = ++lru; pfree(re); return (pg_regexec(&rev[i].cre_re, @@ -84,29 +90,26 @@ RE_compile_and_execute(text *text_re, char *text, int cflags, pmatch, 0) == 0); } } - } - - /* find a previously compiled regular expression */ - for (i = 0; i < rec; i++) - { - if (i == pg_lastre) continue; + i++; - if (rev[i].cre_s) + /* If we were not at the first slot to start, + * then think about wrapping if necessary. + */ + if (pg_lastrec != 0) { - if (strcmp(rev[i].cre_s, re) == 0 && - rev[i].cre_type == cflags) + if (i >= rec) { - rev[i].cre_lru = ++lru; - pfree(re); - return (pg_regexec(&rev[i].cre_re, - text, nmatch, - pmatch, 0) == 0); + i = 0; + } + else if (i == pg_lastrec) + { + break; } } } /* we didn't find it - make room in the cache for it */ - if (rec == MAX_CACHED_RES) + if (rec >= MAX_CACHED_RES) { /* cache is full - find the oldest entry */ for (oldest = 0, i = 1; i < rec; i++) @@ -116,13 +119,16 @@ RE_compile_and_execute(text *text_re, char *text, int cflags, } } else + { oldest = rec++; + } /* if there was an old re, then de-allocate the space it used */ if (rev[oldest].cre_s != (char *) NULL) { for (lru = i = 0; i < rec; i++) { + /* downweight all of the other cached entries */ rev[i].cre_lru = (rev[i].cre_lru - rev[oldest].cre_lru) / 2; if (rev[i].cre_lru > lru) lru = rev[i].cre_lru; @@ -141,6 +147,7 @@ RE_compile_and_execute(text *text_re, char *text, int cflags, regcomp_result = pg_regcomp(&rev[oldest].cre_re, re, cflags); if (regcomp_result == 0) { + pg_lastrec = oldest; /* * use malloc/free for the cre_s field because the storage has to * persist across transactions @@ -311,7 +318,6 @@ textregexsubstr(PG_FUNCTION_ARGS) { text *s = PG_GETARG_TEXT_P(0); text *p = PG_GETARG_TEXT_P(1); - text *result; char *sterm; int len; bool match; @@ -339,16 +345,6 @@ textregexsubstr(PG_FUNCTION_ARGS) Int32GetDatum(pmatch.rm_so+1), Int32GetDatum(pmatch.rm_eo-pmatch.rm_so))); } -#if 0 - /* otherwise, return a zero-length string */ - else - { - result = palloc(VARHDRSZ); - VARATT_SIZEP(result) = VARHDRSZ; - PG_RETURN_TEXT_P(result); - } -#endif - /* not reached */ PG_RETURN_NULL(); } |