Make the man(1) and apropos(1) options -s and -S much less expensive:

Do not append an SQL clause looking into the large "keys" table.
Instead, filter the result of the SQL query in buildnames() where
equivalent data from the much smaller "mlinks" table is already
available for free.

This is relevant because man(1) uses the equivalent of "-S ${MACHINE}"
by default since main.c rev. 1.216, to make sure that manuals for
the current architecture are shown.  With many ports installed, this
patch can speed up man(1) by a factor of more than a hundred.

Slowness reported by Theo Buehler <theo at math dot ethz dot ch>, thanks!

1 files changed, 23 insertions, 49 deletions

diff --git a/mansearch.c b/mansearch.c
index dbfbe025..a4d40544 100644
--- a/mansearch.c
+++ b/mansearch.c
@@ -1,7 +1,7 @@
-/*	$Id: mansearch.c,v 1.52 2014/12/06 01:23:24 schwarze Exp $ */
+/*	$Id: mansearch.c,v 1.53 2015/01/20 18:21:18 schwarze Exp $ */
 /*
  * Copyright (c) 2012 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2013, 2014 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2013, 2014, 2015 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -85,7 +85,8 @@ struct	match {
 	int		 form; /* bit field: formatted, zipped? */
 };
 
-static	void		 buildnames(struct manpage *, sqlite3 *,
+static	void		 buildnames(const struct mansearch *,
+				struct manpage *, sqlite3 *,
 				sqlite3_stmt *, uint64_t,
 				const char *, int form);
 static	char		*buildoutput(sqlite3 *, sqlite3_stmt *,
@@ -96,8 +97,6 @@ static	void		*hash_calloc(size_t, size_t, void *);
 static	struct expr	*exprcomp(const struct mansearch *,
 				int, char *[]);
 static	void		 exprfree(struct expr *);
-static	struct expr	*exprspec(struct expr *, uint64_t,
-				 const char *, const char *);
 static	struct expr	*exprterm(const struct mansearch *, char *, int);
 static	int		 manpage_compare(const void *, const void *);
 static	void		 sql_append(char **sql, size_t *sz,
@@ -343,14 +342,16 @@ mansearch(const struct mansearch *search,
 			mpage->bits = mp->bits;
 			mpage->sec = 10;
 			mpage->form = mp->form;
-			buildnames(mpage, db, s, mp->pageid,
+			buildnames(search, mpage, db, s, mp->pageid,
 			    paths->paths[i], mp->form);
-			mpage->output = TYPE_Nd & outbit ?
-			    mp->desc : outbit ?
-			    buildoutput(db, s2, mp->pageid, outbit) : NULL;
-
+			if (mpage->names != NULL) {
+				mpage->output = TYPE_Nd & outbit ?
+				    mp->desc : outbit ?
+				    buildoutput(db, s2, mp->pageid, outbit) :
+				    NULL;
+				cur++;
+			}
 			free(mp);
-			cur++;
 		}
 
 		sqlite3_finalize(s);
@@ -407,7 +408,8 @@ manpage_compare(const void *vp1, const void *vp2)
 }
 
 static void
-buildnames(struct manpage *mpage, sqlite3 *db, sqlite3_stmt *s,
+buildnames(const struct mansearch *search, struct manpage *mpage,
+		sqlite3 *db, sqlite3_stmt *s,
 		uint64_t pageid, const char *path, int form)
 {
 	char		*newnames, *prevsec, *prevarch;
@@ -432,10 +434,15 @@ buildnames(struct manpage *mpage, sqlite3 *db, sqlite3_stmt *s,
 			sep1 = ", ";
 		}
 
-		/* Fetch the next name. */
+		/* Fetch the next name, rejecting sec/arch mismatches. */
 
 		sec = (const char *)sqlite3_column_text(s, 0);
+		if (search->sec != NULL && strcasecmp(sec, search->sec))
+			continue;
 		arch = (const char *)sqlite3_column_text(s, 1);
+		if (search->arch != NULL && *arch != '\0' &&
+		    strcasecmp(arch, search->arch))
+			continue;
 		name = (const char *)sqlite3_column_text(s, 2);
 
 		/* Remember the first section found. */
@@ -645,8 +652,7 @@ exprcomp(const struct mansearch *search, int argc, char *argv[])
 	struct expr	*first, *prev, *cur, *next;
 
 	first = cur = NULL;
-	logic = igncase = toclose = 0;
-	toopen = NULL != search->sec || NULL != search->arch;
+	logic = igncase = toopen = toclose = 0;
 
 	for (i = 0; i < argc; i++) {
 		if (0 == strcmp("(", argv[i])) {
@@ -712,17 +718,8 @@ exprcomp(const struct mansearch *search, int argc, char *argv[])
 
 		toopen = logic = igncase = 0;
 	}
-	if (toopen || logic || igncase || toclose)
-		goto fail;
-
-	if (NULL != search->sec || NULL != search->arch)
-		cur->close++;
-	if (NULL != search->arch)
-		cur = exprspec(cur, TYPE_arch, search->arch, "^(%s|any)$");
-	if (NULL != search->sec)
-		exprspec(cur, TYPE_sec, search->sec, "^%s$");
-
-	return(first);
+	if ( ! (toopen || logic || igncase || toclose))
+		return(first);
 
 fail:
 	if (NULL != first)
@@ -731,29 +728,6 @@ fail:
 }
 
 static struct expr *
-exprspec(struct expr *cur, uint64_t key, const char *value,
-		const char *format)
-{
-	char	 errbuf[BUFSIZ];
-	char	*cp;
-	int	 irc;
-
-	mandoc_asprintf(&cp, format, value);
-	cur->next = mandoc_calloc(1, sizeof(struct expr));
-	cur = cur->next;
-	cur->and = 1;
-	cur->bits = key;
-	if (0 != (irc = regcomp(&cur->regexp, cp,
-	    REG_EXTENDED | REG_NOSUB | REG_ICASE))) {
-		regerror(irc, &cur->regexp, errbuf, sizeof(errbuf));
-		fprintf(stderr, "regcomp: %s\n", errbuf);
-		cur->substr = value;
-	}
-	free(cp);
-	return(cur);
-}
-
-static struct expr *
 exprterm(const struct mansearch *search, char *buf, int cs)
 {
 	char		 errbuf[BUFSIZ];