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| author | Bryce Kwon <bryce@brycekwon.com> | |
|---|---|---|
| committer | Bryce Kwon <bryce@brycekwon.com> | |
| commit | ||
| parent | ||
| tree | ||
| download | ||
Stop caching clone files and oversized responses
The dumb transport reads files that already sit on the disk, so a pack
copied into a slot cost that disk twice and the request a second write
of every byte. A snapshot took a slot whatever its size, so a visitor
naming distinct refs and ids could fill the cache root with archives.
cache-max-slot-size, 64 MB unless set, now serves a larger response from
the lock file and drops it, along with any expired copy it would have
replaced.
Diffstat (limited to 'source/cache.c')
| -rw-r--r-- | source/cache.c | 25 |
1 file changed, 22 insertions, 3 deletions
diff --git a/source/cache.c b/source/cache.c index 091c078..8c81f5c 100644 --- a/source/cache.c +++ b/source/cache.c @@ -60,6 +60,11 @@ struct cache_slot { // page has already reached the visitor and nothing more may be served // after it, not the lock file and not the stale copy still open. int abandoned; + // The largest page a slot may keep, with zero for no bound, and whether + // the fill went past it, in which case the lock file is served and then + // dropped instead of published. + size_t max_bytes; + int oversized; // The slot as it was when it was opened, or the lock file once // fill_slot has written a page into it. struct stat st; @@ -374,6 +379,7 @@ static int fill_slot(struct cache_slot *slot) // it copies after a fill is the lock file rather than the old slot. if (fstat(slot->lock_fd, &slot->st)) return errno; + slot->oversized = slot->max_bytes && (size_t)slot->st.st_size > slot->max_bytes; return 0; } @@ -398,7 +404,14 @@ static void refresh_slot(struct cache_slot *slot) close_lock(slot); } else { close_slot(slot); - publish_slot(slot); + if (slot->oversized) { + // The expired copy goes too, or every later request + // would refill it and drop the result again. + unlink(slot->path); + unlock_slot(slot, 0); + } else { + publish_slot(slot); + } slot->cache_fd = slot->lock_fd; } } @@ -460,7 +473,10 @@ static int process_slot(struct cache_slot *slot) // concurrent writer put there for a different key, so what gets // printed is the descriptor still open on the lock file. slot->cache_fd = slot->lock_fd; - publish_slot(slot); + if (slot->oversized) + unlock_slot(slot, 0); + else + publish_slot(slot); err = serve_slot(slot); close_slot(slot); return err; @@ -500,7 +516,8 @@ unsigned long cache_hash_str(const char *str) return h; } -int cache_process(int size, const char *path, const char *key, int ttl, cache_fill_fn fn) +int cache_process(int size, const char *path, const char *key, int ttl, size_t max_bytes, + cache_fill_fn fn) { unsigned long hash; int i; @@ -539,6 +556,8 @@ int cache_process(int size, const char *path, const char *key, int ttl, cache_fi slot.ttl = ttl; slot.saved_stdout = -1; slot.abandoned = 0; + slot.max_bytes = max_bytes; + slot.oversized = 0; slot.path = slot_path.buf; slot.lock_path = lock_path.buf; slot.key = key; |