[MERGE] Enable caching of negative revision lookups in RemoteRepository write locks when no _real_repository has been constructed.

[John Arbash Meinel]

John Arbash Meinel has voted tweak.
Status is now: Conditionally approved
Comment:
          if self._real_repository is None:
+            self._unstacked_provider.missing_keys.clear()
              self.bzrdir._ensure_real()
              self._set_real_repository(
                  self.bzrdir._real_bzrdir.open_repository())

^- Don't you need to call 
self._unstacked_provider.enable_cache(cache_misses=True) at this point?

Then it seems consistent with:
+            cache_misses = self._real_repository is None
+ 
self._unstacked_provider.enable_cache(cache_misses=cache_misses)

(so on the first request, if the real_repo isn't present, you cache 
misses, until something calls _ensure_real, then you stop caching 
misses).

I'm not 100% sure about this one:
      def insert_stream(self, stream, src_format, resume_tokens):
          target = self.target_repo
+        target._unstacked_provider.missing_keys.clear()
          if target._lock_token:
              verb = 'Repository.insert_stream_locked'
              extra_args = (target._lock_token or '',)


Though my guess is that you wouldn't have to stop caching misses as long 
as _real_repo isn't invoked yet. You could even get away with looping 
over the stream and only removing ones that are seen, but this is 
certainly simpler.



For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C1240901973.5830.19.camel%40lifeless-64%3E
Project: Bazaar