Rebuild the microdesc cache when a sufficient number of bytes are dropped

Previously on 0.2.2, we'd never clean the cache.  Now that we can
clean it, we want to add a condition to rebuild it: that should happen
whenever we have dropped enough microdescriptors that we could save a
lot of space.

No changes file, since 0.2.3 doesn't need one and 0.2.2 already has some
changes files for the backport of the microdesc_clean_cahce() function.
This commit is contained in:
Nick Mathewson 2011-05-03 17:03:49 -04:00
parent 56fbd728c2
commit cb6c909664
2 changed files with 34 additions and 13 deletions

View File

@ -177,6 +177,8 @@ microdescs_add_list_to_cache(microdesc_cache_t *cache,
if (md2->last_listed < md->last_listed)
md2->last_listed = md->last_listed;
microdesc_free(md);
if (where != SAVED_NOWHERE)
cache->bytes_dropped += size;
continue;
}
@ -206,14 +208,7 @@ microdescs_add_list_to_cache(microdesc_cache_t *cache,
if (f)
finish_writing_to_file(open_file); /*XXX Check me.*/
{
size_t old_content_len =
cache->cache_content ? cache->cache_content->size : 0;
if (cache->journal_len > 16384 + old_content_len &&
cache->journal_len > old_content_len / 2) {
microdesc_cache_rebuild(cache);
}
}
microdesc_cache_rebuild(cache, 0/* only as needed */);
return added;
}
@ -275,6 +270,9 @@ microdesc_cache_reload(microdesc_cache_t *cache)
}
log_notice(LD_DIR, "Reloaded microdescriptor cache. Found %d descriptors.",
total);
microdesc_cache_clean(cache, 0, 0);
return 0;
}
@ -323,11 +321,30 @@ microdesc_cache_clean(microdesc_cache_t *cache, time_t cutoff, int force)
}
}
static int
should_rebuild_md_cache(microdesc_cache_t *cache)
{
const size_t old_len =
cache->cache_content ? cache->cache_content->size : 0;
const size_t journal_len = cache->journal_len;
const size_t dropped = cache->bytes_dropped;
if (journal_len < 16384)
return 0; /* Don't bother, not enough has happened yet. */
if (dropped > (journal_len + old_len) / 3)
return 1; /* We could save 1/3 or more of the currently used space. */
if (journal_len > old_len / 2)
return 1; /* We should append to the regular file */
return 0;
}
/** Regenerate the main cache file for <b>cache</b>, clear the journal file,
* and update every microdesc_t in the cache with pointers to its new
* location. */
* location. If <b>force</b> is true, do this unconditionally. If
* <b>force</b> is false, do it only if we expect to save space on disk. */
int
microdesc_cache_rebuild(microdesc_cache_t *cache)
microdesc_cache_rebuild(microdesc_cache_t *cache, int force)
{
open_file_t *open_file;
FILE *f;
@ -337,11 +354,14 @@ microdesc_cache_rebuild(microdesc_cache_t *cache)
off_t off = 0;
int orig_size, new_size;
log_info(LD_DIR, "Rebuilding the microdescriptor cache...");
/* Remove dead descriptors */
microdesc_cache_clean(cache, 0/*cutoff*/, 0/*force*/);
if (!force && !should_rebuild_md_cache(cache))
return 0;
log_info(LD_DIR, "Rebuilding the microdescriptor cache...");
orig_size = (int)(cache->cache_content ? cache->cache_content->size : 0);
orig_size += (int)cache->journal_len;
@ -396,6 +416,7 @@ microdesc_cache_rebuild(microdesc_cache_t *cache)
write_str_to_file(cache->journal_fname, "", 1);
cache->journal_len = 0;
cache->bytes_dropped = 0;
new_size = (int)cache->cache_content->size;
log_info(LD_DIR, "Done rebuilding microdesc cache. "

View File

@ -22,7 +22,7 @@ smartlist_t *microdescs_add_list_to_cache(microdesc_cache_t *cache,
int no_save);
void microdesc_cache_clean(microdesc_cache_t *cache, time_t cutoff, int force);
int microdesc_cache_rebuild(microdesc_cache_t *cache);
int microdesc_cache_rebuild(microdesc_cache_t *cache, int force);
int microdesc_cache_reload(microdesc_cache_t *cache);
void microdesc_cache_clear(microdesc_cache_t *cache);