Optimise -fstype NOTUSED to -false at -O2.
* find/parser.c: Include mountlist.h.
(insert_false): New function, inserts a -false predicate.
(parse_false): Use insert_false.
(is_used_fs_type): New function, determines if any mounted
filesystem is of the named type.
(parse_fstype): At optimisation level 2 and above, -fstpe FOO
is converted to -false if no mounted filesytem is of type FOO.
* find/find.1: Document this optimisation.
* doc/find.texi (Optimisation Options): Likewise.
* NEWS: Mention this change.
---
ChangeLog | 12 ++++++++
NEWS | 7 +++++
doc/find.texi | 6 ++++
find/find.1 | 9 ++++++
find/parser.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++---------
5 files changed, 102 insertions(+), 14 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index e069683..eab9e91 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -219,6 +219,18 @@
(parse_iwholename): Remove redundant extra definition.
(parse_ipath): Likewise.
+ Optimise -fstype NOTUSED to -false at -O2.
+ * find/parser.c: Include mountlist.h.
+ (insert_false): New function, inserts a -false predicate.
+ (parse_false): Use insert_false.
+ (is_used_fs_type): New function, determines if any mounted
+ filesystem is of the named type.
+ (parse_fstype): At optimisation level 2 and above, -fstpe FOO
+ is converted to -false if no mounted filesytem is of type FOO.
+ * find/find.1: Document this optimisation.
+ * doc/find.texi (Optimisation Options): Likewise.
+ * NEWS: Mention this change.
+
2009-07-14 James Youngman <j...@gnu.org>
Fix Savannah bug #27017: find -D opt / -fstype ext3 -print , -quit
diff --git a/NEWS b/NEWS
index 29b78f9..5088dd2 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,13 @@ GNU findutils NEWS - User visible changes. -*- outline -*-
(allout)
* Major changes in release 4.5.6-git, YYYY-MM-DD
+** Performance changes
+
+If you use the -fstype FOO predicate and specify a filsystem type FOO
+which is not known (e.g. present in /etc/mtab) at the time find
+starts, that predicate is now equivalent to -false. This substitution
+currently occurs at optimisation level 2 and above.
+
** Bug Fixes
#28872: Mistake in "#safer" example in "Problems with -exec and
diff --git a/doc/find.texi b/doc/find.texi
index c2c2c03..3b21c0a 100644
--- a/doc/find.texi
+++ b/doc/find.texi
@@ -3106,6 +3106,12 @@ information from the inode. On many modern versions of
Unix, file
types are returned by @code{readdir()} and so these predicates are
faster to evaluate than predicates which need to stat the file first.
+If you use the @samp{-fstype FOO} predicate and specify a filsystem
+type @samp{FOO} which is not known (that is, present in
+...@file{/etc/mtab}) at the time @code{find} starts, that predicate is
+equivalent to @samp{-false}.
+
+
@item 3
At this optimisation level, the full cost-based query optimiser is
enabled. The order of tests is modified so that cheap (i.e., fast)
diff --git a/find/find.1 b/find/find.1
index e17b21e..34daf54 100644
--- a/find/find.1
+++ b/find/find.1
@@ -253,6 +253,15 @@ modern versions of Unix, file types are returned by
.B readdir()
and so these predicates are faster to evaluate than predicates which
need to stat the file first.
+If you use the
+.B \-fstype
+.I FOO
+predicate and specify a filsystem type
+.I FOO
+which is not known (that is, present in `/etc/mtab') at the time
+.B find
+starts, that predicate is equivalent to
+.BR \-false .
.IP 3
At this optimisation level, the full cost-based query optimiser is
enabled. The order of tests is modified so that cheap (i.e. fast)
diff --git a/find/parser.c b/find/parser.c
index 5fdb949..8a15148 100644
--- a/find/parser.c
+++ b/find/parser.c
@@ -26,6 +26,7 @@
#include <errno.h>
#include <grp.h>
#include <fnmatch.h>
+#include "mountlist.h"
#include "modechange.h"
#include "modetype.h"
#include "xstrtol.h"
@@ -854,20 +855,26 @@ parse_execdir (const struct parser_table* entry, char
**argv, int *arg_ptr)
}
static boolean
-parse_false (const struct parser_table* entry, char **argv, int *arg_ptr)
+insert_false(void)
{
struct predicate *our_pred;
+ const struct parser_table *entry_false;
- (void) argv;
- (void) arg_ptr;
-
- our_pred = insert_primary_noarg (entry);
+ entry_false = find_parser("false");
+ our_pred = insert_primary_noarg (entry_false);
our_pred->need_stat = our_pred->need_type = false;
our_pred->side_effects = our_pred->no_default_print = false;
our_pred->est_success_rate = 0.0f;
return true;
}
+
+static boolean
+parse_false (const struct parser_table* entry, char **argv, int *arg_ptr)
+{
+ return insert_false ();
+}
+
static boolean
insert_fls (const struct parser_table* entry, const char *filename)
{
@@ -969,22 +976,69 @@ static float estimate_fstype_success_rate(const char
*fsname)
}
+
+static boolean
+is_used_fs_type(const char *name)
+{
+ if (0 == strcmp("afs", name))
+ {
+ /* I guess AFS may not appear in /etc/mtab (or equivalent) but still be
in use,
+ so assume we always need to check for AFS. */
+ return true;
+ }
+ else
+ {
+ const struct mount_entry *entries = read_file_system_list(false);
+ if (entries)
+ {
+ const struct mount_entry *entry;
+ for (entry = entries; entry; entry = entry->me_next)
+ {
+ if (0 == strcmp(name, entry->me_type))
+ return true;
+ }
+ }
+ else
+ {
+ return true;
+ }
+ }
+ return false;
+}
+
+
static boolean
parse_fstype (const struct parser_table* entry, char **argv, int *arg_ptr)
{
const char *typename;
if (collect_arg(argv, arg_ptr, &typename))
{
- struct predicate *our_pred = insert_primary (entry, typename);
- our_pred->args.str = typename;
+ if (options.optimisation_level < 2 || is_used_fs_type (typename))
+ {
+ struct predicate *our_pred = insert_primary (entry, typename);
+ our_pred->args.str = typename;
- /* This is an expensive operation, so although there are
- * circumstances where it is selective, we ignore this fact
- * because we probably don't want to promote this test to the
- * front anyway.
- */
- our_pred->est_success_rate = estimate_fstype_success_rate(typename);
- return true;
+ /* This is an expensive operation, so although there are
+ * circumstances where it is selective, we ignore this fact
+ * because we probably don't want to promote this test to the
+ * front anyway.
+ */
+ our_pred->est_success_rate = estimate_fstype_success_rate(typename);
+ return true;
+ }
+ else
+ {
+ /* This filesystem type is not listed in the mount table.
+ * Hence this predicate will always return false (with this argument).
+ * Substitute a predicate with the same effect as -false.
+ */
+ if (options.debug_options & DebugTreeOpt)
+ {
+ fprintf(stderr,
+ "-fstype %s can never succeed, substituting -false\n",
typename);
+ }
+ return insert_false ();
+ }
}
else
{
--
1.5.6.5
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