Change usage to reuse the cache for the hash computation.

piptools/repositories/base.py

@@ -3,6 +3,7 @@
                         unicode_literals)
 
 from abc import ABCMeta, abstractmethod
+from contextlib import contextmanager
 
 from six import add_metaclass
 
@@ -38,3 +39,10 @@ def get_hashes(self, ireq):
         all of the files for a given requirement. It is not acceptable for an
         editable or unpinned requirement to be passed to this function.
         """
+
+    @abstractmethod
+    @contextmanager
+    def allow_all_wheels(self):
+        """
+        Monkey patches pip.Wheel to allow wheels from all platforms and Python versions.
+        """

piptools/repositories/local.py

@@ -2,6 +2,8 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
+from contextlib import contextmanager
+
 from piptools.utils import as_tuple, key_from_req, make_install_requirement
 from .base import BaseRepository
 
@@ -63,3 +65,8 @@ def get_dependencies(self, ireq):
 
     def get_hashes(self, ireq):
         return self.repository.get_hashes(ireq)
+
+    @contextmanager
+    def allow_all_wheels(self):
+        with self.repository.allow_all_wheels():
+            yield

piptools/repositories/pypi.py

@@ -165,12 +165,11 @@ def get_hashes(self, ireq):
         # We need to get all of the candidates that match our current version
         # pin, these will represent all of the files that could possibly
         # satisfy this constraint.
-        with self.allow_all_wheels():
-            all_candidates = self.find_all_candidates(ireq.name)
-            candidates_by_version = lookup_table(all_candidates, key=lambda c: c.version)
-            matching_versions = list(
-                ireq.specifier.filter((candidate.version for candidate in all_candidates)))
-            matching_candidates = candidates_by_version[matching_versions[0]]
+        all_candidates = self.find_all_candidates(ireq.name)
+        candidates_by_version = lookup_table(all_candidates, key=lambda c: c.version)
+        matching_versions = list(
+            ireq.specifier.filter((candidate.version for candidate in all_candidates)))
+        matching_candidates = candidates_by_version[matching_versions[0]]
 
         return {
             self._get_file_hash(candidate.location)

piptools/resolver.py

@@ -68,7 +68,8 @@ def resolve_hashes(self, ireqs):
         """
         Finds acceptable hashes for all of the given InstallRequirements.
         """
-        return {ireq: self.repository.get_hashes(ireq) for ireq in ireqs}
+        with self.repository.allow_all_wheels():
+            return {ireq: self.repository.get_hashes(ireq) for ireq in ireqs}
 
     def resolve(self, max_rounds=10):
         """

tests/conftest.py

@@ -1,4 +1,5 @@
 import json
+from contextlib import contextmanager
 from functools import partial
 
 from pip._vendor.packaging.version import Version
@@ -49,6 +50,11 @@ def get_dependencies(self, ireq):
         dependencies = [dep for extra in extras for dep in self.index[name][version][extra]]
         return [InstallRequirement.from_line(dep, constraint=ireq.constraint) for dep in dependencies]
 
+    @contextmanager
+    def allow_all_wheels(self):
+        # No need to do an actual pip.Wheel mock here.
+        yield
+
 
 class FakeInstalledDistribution(object):
     def __init__(self, line, deps=None):

tests/test_repository_pypi.py

@@ -52,7 +52,8 @@ def test_generate_hashes_all_platforms(from_line):
     session = pip_command._build_session(pip_options)
     repository = PyPIRepository(pip_options, session)
     ireq = from_line('cffi==1.9.1')
-    assert repository.get_hashes(ireq) == expected
+    with repository.allow_all_wheels():
+        assert repository.get_hashes(ireq) == expected
 
 
 def test_generate_hashes_without_interfering_with_each_other(from_line):