commit 8afbc154f794835633559f81a89232f1bccc1d8e Author: Nick Mathewson nickm@torproject.org Date: Mon Aug 10 14:27:23 2015 -0400
Remove a 9-function strongly connected component of tor's callgraph.
microdesc_free_() called get_microdesc_cache(), which had the fun side-effect of potentially reloading the whole cache from disk. Replace it with a variant that doesn't. --- changes/microdesc_cycle | 4 ++++ src/or/microdesc.c | 27 +++++++++++++++++++++++---- 2 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/changes/microdesc_cycle b/changes/microdesc_cycle new file mode 100644 index 0000000..fddc2be --- /dev/null +++ b/changes/microdesc_cycle @@ -0,0 +1,4 @@ + o Code simplification and refactoring: + - Simplify the microdesc_free() implementation so that it no longer + appears (to code analysis tools) to potentially invoke a huge suite + of other microdesc functions. diff --git a/src/or/microdesc.c b/src/or/microdesc.c index ee48f6a..051603d 100644 --- a/src/or/microdesc.c +++ b/src/or/microdesc.c @@ -39,8 +39,13 @@ struct microdesc_cache_t { uint64_t total_len_seen; /** Total number of microdescriptors we have added to this cache */ unsigned n_seen; + + /** True iff we have loaded this cache from disk ever. */ + int is_loaded; };
+static microdesc_cache_t *get_microdesc_cache_noload(void); + /** Helper: computes a hash of <b>md</b> to place it in a hash table. */ static INLINE unsigned int microdesc_hash_(microdesc_t *md) @@ -113,12 +118,24 @@ static microdesc_cache_t *the_microdesc_cache = NULL; microdesc_cache_t * get_microdesc_cache(void) { + microdesc_cache_t *cache = get_microdesc_cache_noload(); + if (PREDICT_UNLIKELY(cache->is_loaded == 0)) { + microdesc_cache_reload(cache); + } + return cache; +} + +/** Return a pointer to the microdescriptor cache, creating (but not loading) + * it if necessary. */ +static microdesc_cache_t * +get_microdesc_cache_noload(void) +{ if (PREDICT_UNLIKELY(the_microdesc_cache==NULL)) { - microdesc_cache_t *cache = tor_malloc_zero(sizeof(microdesc_cache_t)); + microdesc_cache_t *cache = tor_malloc_zero(sizeof(*cache)); + tor_malloc_zero(sizeof(microdesc_cache_t)); HT_INIT(microdesc_map, &cache->map); cache->cache_fname = get_datadir_fname("cached-microdescs"); cache->journal_fname = get_datadir_fname("cached-microdescs.new"); - microdesc_cache_reload(cache); the_microdesc_cache = cache; } return the_microdesc_cache; @@ -353,6 +370,8 @@ microdesc_cache_reload(microdesc_cache_t *cache)
microdesc_cache_clear(cache);
+ cache->is_loaded = 1; + mm = cache->cache_content = tor_mmap_file(cache->cache_fname); if (mm) { added = microdescs_add_to_cache(cache, mm->data, mm->data+mm->size, @@ -697,7 +716,7 @@ microdesc_free_(microdesc_t *md, const char *fname, int lineno) /* Make sure that the microdesc was really removed from the appropriate data structures. */ if (md->held_in_map) { - microdesc_cache_t *cache = get_microdesc_cache(); + microdesc_cache_t *cache = get_microdesc_cache_noload(); microdesc_t *md2 = HT_FIND(microdesc_map, &cache->map, md); if (md2 == md) { log_warn(LD_BUG, "microdesc_free() called from %s:%d, but md was still " @@ -710,7 +729,7 @@ microdesc_free_(microdesc_t *md, const char *fname, int lineno) tor_fragile_assert(); } if (md->held_by_nodes) { - microdesc_cache_t *cache = get_microdesc_cache(); + microdesc_cache_t *cache = get_microdesc_cache_noload(); int found=0; const smartlist_t *nodes = nodelist_get_list(); const int ht_badness = HT_REP_IS_BAD_(microdesc_map, &cache->map);