Add a hashtable to consdiffmgr to keep track of diff status

In several places in the old code, we had problems that only an
in-memory index of diff status could solve, including:
   * Remembering which diffs were in-progress, so that we didn't
     re-launch them.
   * Remembering which diffs had failed, so that we didn't try to
     recompute them over and over.
   * Having a fast way to look up the diff from a given consensus to
     the latest consensus of a given flavor.

This patch adds a hashtable mapping from (flavor, source diff), to
solve the problem.  It maps to a cache entry handle, rather than to
a cache entry directly, so that it doesn't affect the reference
counts of the cache entries, and so that we don't otherwise need to
worry about lifetime management.

0 files changed, 0 insertions, 0 deletions