openSUSE / osc-plugin-factory / 1816

30%

Pull #629

travis-ci

Provide cache for expensive and cache-able staging requests.

The two slowest staging API calls are for information that rarely changes.
By caching the result the commands typically execute over twice as fast.
Going further can see improvements of an order of magnitude or more by
caching almost all the GET requests.

In contrast to osclib/memoize.py this cache operates at the HTTP request
level. This has several advantages:

- Caches the expensive part (ie the HTTP request). There are a number of
  functions in osc.core and elsewhere that make the same API request, but
  process the result differently which would require multiple API calls
  using memoize.
- Handles cases were a loader function uses class attributes as input and
  output and thus no relevant method parameters or return. An important
  example is StagingAPI._generate_ring_packages().
- Storage is project aware which allows caches to be deleted when a project
  is known to have changed.
- Due to project awareness, can utilize OBS /statistics/latest_updated API
  call to determine which projects need to be expired.

The cache file structure is as follows:

- hostname(apiurl)
  - project
    - sha1(url)
  - sha1(url)

See Cache.PATTERNS for changing the time to live (ttl) or add patterns to
be cached.

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