Utilize GetMulti.

src/python/pants/engine/build_files.py

@@ -36,10 +36,6 @@ def _key_func(entry):
   return key
 
 
-class BuildDirs(datatype('BuildDirs', ['dependencies'])):
-  """A list of Stat objects for directories containing build files."""
-
-
 class Specs(Collection.of(Spec)):
   """A collection of Spec subclasses."""
 
@@ -209,17 +205,18 @@ def _hydrate(item_type, spec_path, **kwargs):
   return item
 
 
-@rule(BuildFileAddresses,
-      [Select(AddressMapper),
-       SelectDependencies(AddressFamily, BuildDirs, field_types=(Dir,)),
-       Select(Specs)])
-def addresses_from_address_families(address_mapper, address_families, specs):
+@rule(BuildFileAddresses, [Select(AddressMapper), Select(Specs)])
+def addresses_from_address_families(address_mapper, specs):
   """Given a list of AddressFamilies matching a list of Specs, return matching Addresses.
 
   Raises a AddressLookupError if:
      - there were no matching AddressFamilies, or
      - the Spec matches no addresses for SingleAddresses.
   """
+  # Capture a Snapshot covering all paths for these Specs, then group by directory.
+  snapshot = yield Get(Snapshot, _spec_to_globs(address_mapper, specs))
+  dirnames = set(dirname(f.stat.path) for f in snapshot.files)
+  address_families = yield [Get(AddressFamily, Dir(d)) for d in dirnames]
 
   # NB: `@memoized` does not work on local functions.
   def by_directory():
@@ -281,20 +278,11 @@ def include(address_families, predicate=None):
     else:
       raise ValueError('Unrecognized Spec type: {}'.format(spec))
 
-  return BuildFileAddresses(addresses)
+  yield BuildFileAddresses(addresses)
 
 
-@rule(BuildDirs, [Select(AddressMapper), Select(Snapshot)])
-def filter_build_dirs(address_mapper, snapshot):
-  """Given a Snapshot matching a build pattern, return parent directories as BuildDirs."""
-  dirnames = set(dirname(f.stat.path) for f in snapshot.files)
-  return BuildDirs(tuple(Dir(d) for d in dirnames))
-
-
-@rule(PathGlobs, [Select(AddressMapper), Select(Specs)])
-def spec_to_globs(address_mapper, specs):
-  """Given a Spec object, return a PathGlobs object for the build files that it matches.
-  """
+def _spec_to_globs(address_mapper, specs):
+  """Given a Specs object, return a PathGlobs object for the build files that it matches."""
   patterns = set()
   for spec in specs.dependencies:
     if type(spec) is DescendantAddresses:
@@ -365,8 +353,6 @@ def create_graph_rules(address_mapper, symbol_table):
     # Spec handling: locate directories that contain build files, and request
     # AddressFamilies for each of them.
     addresses_from_address_families,
-    filter_build_dirs,
-    spec_to_globs,
     # Root rules representing parameters that might be provided via root subjects.
     RootRule(Address),
     RootRule(BuildFileAddress),