From 4dc48da9dbdea09364a67c98f4f3d3b4499d4b7d Mon Sep 17 00:00:00 2001
From: Xavier Fernandez <xavier.fernandez@polyconseil.fr>
Date: Sat, 31 Oct 2020 15:54:54 +0100
Subject: [PATCH 1/2] utils: make Hashes object hashable

---
 src/pip/_internal/utils/hashes.py | 23 ++++++++++++++++++++++-
 tests/unit/test_utils.py          | 10 ++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/pip/_internal/utils/hashes.py b/src/pip/_internal/utils/hashes.py
index b306dafe7d7..4d90f5bfda4 100644
--- a/src/pip/_internal/utils/hashes.py
+++ b/src/pip/_internal/utils/hashes.py
@@ -39,7 +39,12 @@ def __init__(self, hashes=None):
         :param hashes: A dict of algorithm names pointing to lists of allowed
             hex digests
         """
-        self._allowed = {} if hashes is None else hashes
+        allowed = {}
+        if hashes is not None:
+            for alg, keys in hashes.items():
+                # Make sure values are always sorted (to ease equality checks)
+                allowed[alg] = sorted(keys)
+        self._allowed = allowed
 
     def __and__(self, other):
         # type: (Hashes) -> Hashes
@@ -128,6 +133,22 @@ def __bool__(self):
         # type: () -> bool
         return self.__nonzero__()
 
+    def __eq__(self, other):
+        # type: (object) -> bool
+        if not isinstance(other, Hashes):
+            return NotImplemented
+        return self._allowed == other._allowed
+
+    def __hash__(self):
+        # type: () -> int
+        return hash(
+            ",".join(sorted(
+                ":".join((alg, digest))
+                for alg, digest_list in self._allowed.items()
+                for digest in digest_list
+            ))
+        )
+
 
 class MissingHashes(Hashes):
     """A workalike for Hashes used when we're missing a hash for a requirement
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index 14b4d74820f..1996b35cb37 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -541,6 +541,16 @@ def test_non_zero(self):
         assert not Hashes()
         assert not Hashes({})
 
+    def test_equality(self):
+        assert Hashes() == Hashes()
+        assert Hashes({'sha256': ['abcd']}) == Hashes({'sha256': ['abcd']})
+        assert Hashes({'sha256': ['ab', 'cd']}) == Hashes({'sha256': ['cd', 'ab']})
+
+    def test_hash(self):
+        cache = {}
+        cache[Hashes({'sha256': ['ab', 'cd']})] = 42
+        assert cache[Hashes({'sha256': ['ab', 'cd']})] == 42
+
 
 class TestEncoding(object):
     """Tests for pip._internal.utils.encoding"""

From 5ec275fca2b8a1944c2b0a19ae4c334febd4929f Mon Sep 17 00:00:00 2001
From: Xavier Fernandez <xavier.fernandez@polyconseil.fr>
Date: Sat, 31 Oct 2020 16:00:11 +0100
Subject: [PATCH 2/2] Cache find_best_candidate results

This is possible because self.make_candidate_evaluator only depends
on:
- the function arguments which are keys to the cache
- self._target_python which never changes during a pip resolution
- self._candidate_prefs which never changes during a pip resolution

On a fresh install, pip install <a package with ~ 100 dependencies>
runs on my machine in:

master (a0e34e9cf707c5)
=======================

0m33.058s
0m34.105s
0m32.426s

This commit
===========

0m15.860s
0m16.254s
0m15.910s

pip 20.2.4 - legacy resolver
============================

0m15.145s
0m15.040s
0m15.152s
---
 src/pip/_internal/index/package_finder.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/pip/_internal/index/package_finder.py b/src/pip/_internal/index/package_finder.py
index b361e194d75..9f39631dde2 100644
--- a/src/pip/_internal/index/package_finder.py
+++ b/src/pip/_internal/index/package_finder.py
@@ -863,6 +863,7 @@ def make_candidate_evaluator(
             hashes=hashes,
         )
 
+    @lru_cache(maxsize=None)
     def find_best_candidate(
         self,
         project_name,       # type: str