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lstat_cache(): print a warning if doing ping-pong between cache types

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This is a debug patch which is only to be used while the lstat_cache()
is in the test stage, and should be removed/reverted before the final
relase.

I think it should be useful to catch these warnings, as I it could be
an indication of that the cache would not be very effective if it is
doing ping-pong by switching between different cache types too many
times.

Also, if someone is experimenting with the lstat_cache(), this patch
will maybe be useful while debugging.

If someone is able to trigger the warning, then send a mail to the GIT
mailing list, containing the first 15 lines of the warning, and a
short description of the GIT commands to trigger the warnings.

I hope someone is willing to use this patch for a while, to be able to
catch possible ping-pong's.

Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Kjetil Barvik 2009-02-09 21:54:53 +01:00 committed by Junio C Hamano
parent 91fcbcbdcd
commit 7734f04873
1 changed files with 23 additions and 0 deletions
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23
symlinks.c
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@ -51,6 +51,11 @@ static inline void reset_lstat_cache(void)
*/
}
#define SWITCHES_BEFORE_WARNING 10
static unsigned int cache_switches, number_of_warnings;
static unsigned int current_cache_func, last_cache_func;
static unsigned int total_calls;
#define FL_DIR (1 << 0)
#define FL_NOENT (1 << 1)
#define FL_SYMLINK (1 << 2)
@ -77,6 +82,7 @@ static int lstat_cache(const char *name, int len,
int match_flags, ret_flags, save_flags, max_len, ret;
struct stat st;
total_calls++;
if (cache.track_flags != track_flags ||
cache.prefix_len_stat_func != prefix_len_stat_func) {
/*
@ -88,6 +94,17 @@ static int lstat_cache(const char *name, int len,
cache.track_flags = track_flags;
cache.prefix_len_stat_func = prefix_len_stat_func;
match_len = last_slash = 0;
cache_switches++;
if (cache_switches > SWITCHES_BEFORE_WARNING) {
if (number_of_warnings < 10 || number_of_warnings % 1000 == 0)
printf("warning from %s:%d cache_switches:%u > %u "\
"(current:%u last:%u total:%u)\n",
__FILE__, __LINE__,
cache_switches, SWITCHES_BEFORE_WARNING,
current_cache_func, last_cache_func,
total_calls);
number_of_warnings++;
}
} else {
/*
* Check to see if we have a match from the cache for
@ -216,6 +233,8 @@ void clear_lstat_cache(void)
*/
int has_symlink_leading_path(const char *name, int len)
{
last_cache_func = current_cache_func;
current_cache_func = 1;
return lstat_cache(name, len,
FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) &
FL_SYMLINK;
@ -227,6 +246,8 @@ int has_symlink_leading_path(const char *name, int len)
*/
int has_symlink_or_noent_leading_path(const char *name, int len)
{
last_cache_func = current_cache_func;
current_cache_func = 2;
return lstat_cache(name, len,
FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT) &
(FL_SYMLINK|FL_NOENT);
@ -241,6 +262,8 @@ int has_symlink_or_noent_leading_path(const char *name, int len)
*/
int has_dirs_only_path(const char *name, int len, int prefix_len)
{
last_cache_func = current_cache_func;
current_cache_func = 3;
return lstat_cache(name, len,
FL_DIR|FL_FULLPATH, prefix_len) &
FL_DIR;