On 10 March 2017 at 10:51, Grazvydas Ignotas <nota...@gmail.com> wrote:
> On Fri, Mar 10, 2017 at 6:23 AM, Timothy Arceri <tarc...@itsqueeze.com> wrote:
>> On 07/03/17 12:25, Alan Swanson wrote:
>>>
>>> Still using random selection of two-character subdirectory in which
>>> to check cache files rather than scanning entire cache.
>>>
>>> v2: Factor out double strlen call
>>> ---
>>> src/util/disk_cache.c | 78
>>> +++++++++++++++++++++++----------------------------
>>> 1 file changed, 35 insertions(+), 43 deletions(-)
>>>
>>> diff --git a/src/util/disk_cache.c b/src/util/disk_cache.c
>>> index 31a9336582..2a923be3dc 100644
>>> --- a/src/util/disk_cache.c
>>> +++ b/src/util/disk_cache.c
>>> @@ -438,70 +438,60 @@ make_cache_file_directory(struct disk_cache *cache,
>>> const cache_key key)
>>> free(dir);
>>> }
>>>
>>> -/* Given a directory path and predicate function, count all entries in
>>> - * that directory for which the predicate returns true. Then choose a
>>> - * random entry from among those counted.
>>> +/* Given a directory path and predicate function, find the entry with
>>> + * the oldest access time in that directory for which the predicate
>>> + * returns true.
>>> *
>>> * Returns: A malloc'ed string for the path to the chosen file, (or
>>> * NULL on any error). The caller should free the string when
>>> * finished.
>>> */
>>> static char *
>>> -choose_random_file_matching(const char *dir_path,
>>> - bool (*predicate)(const struct dirent *,
>>> - const char *dir_path))
>>> +choose_lru_file_matching(const char *dir_path,
>>> + bool (*predicate)(const struct dirent *,
>>> + const char *dir_path))
>>> {
>>> DIR *dir;
>>> struct dirent *entry;
>>> - unsigned int count, victim;
>>> + struct stat sb;
>>> + char *tmp, *lru_name = NULL;
>>> + size_t len;
>>> + time_t lru_atime = 0;
>>
>>
>> Please try to declare variables where they are used. The original version of
>> this file was written before we could use C99 features in Mesa.
>>
>>
>>
>>> char *filename;
>>>
>>> dir = opendir(dir_path);
>>> if (dir == NULL)
>>> return NULL;
>>>
>>> - count = 0;
>>> -
>>> - while (1) {
>>> - entry = readdir(dir);
>>> - if (entry == NULL)
>>> - break;
>>> - if (!predicate(entry, dir_path))
>>> - continue;
>>> -
>>> - count++;
>>> - }
>>> -
>>> - if (count == 0) {
>>> - closedir(dir);
>>> - return NULL;
>>> - }
>>> -
>>> - victim = rand() % count;
>>> -
>>> - rewinddir(dir);
>>> - count = 0;
>>> -
>>> while (1) {
>>> entry = readdir(dir);
>>> if (entry == NULL)
>>> break;
>>> if (!predicate(entry, dir_path))
>>> continue;
>>> - if (count == victim)
>>> - break;
>>>
>>> - count++;
>>> + if (fstatat(dirfd(dir), entry->d_name, &sb, 0) == 0) {
>>> + if (!lru_atime || (sb.st_atime < lru_atime)) {
>>> + len = strlen(entry->d_name) + 1;
>>> + tmp = realloc(lru_name, len);
>>> + if (tmp) {
>>> + lru_name = tmp;
>>
>>
>> I don't think we need tmp here. Why not use lru_name directly?
>
> It *is* needed, otherwise if realloc fails, you'll leak old memory.
>
Indeed. Alternatively one can avoid all the strlen/realloc/free dances
by using NAME_MAX.
As per the POSIX manual
"The array d_name is of unspecified size, but shall contain a filename
of at most {NAME_MAX} bytes followed by a terminating null byte."
Not 100% sure if it'll play well with Hurd and similar platforms :-\
-Emil
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