- # reload the source and regenerate the cache
- cfg = wrap(file(src_path), lambda f: yaml.load(f, default_loader))
- try: wrap(file(cache_path, 'w'), lambda f: f.write(json.write(cfg)))
- except: pass # silent failure
+ # Atomically reload the source and regenerate the cache. The read and
+ # write must be a single transaction, or a stale version may be
+ # written.
+ @with_lock_file('/var/lib/invirt/cache.lock')
+ def cfg():
+ cfg = with_closing(file(src_path))(lambda f: yaml.load(f, default_loader))
+ try: with_closing(file(cache_path, 'w'))(lambda f: f.write(json.write(cfg)))
+ except: pass # silent failure
+ return cfg