Use a set for TargetPython.get_tags for performance (pypa#12204)

news/12204.feature.rst

@@ -0,0 +1 @@
+Improve use of datastructures to make candidate selection 1.6x faster

src/pip/_internal/commands/debug.py

@@ -105,7 +105,7 @@ def show_tags(options: Values) -> None:
     tag_limit = 10
 
     target_python = make_target_python(options)
-    tags = target_python.get_tags()
+    tags = target_python.get_sorted_tags()
 
     # Display the target options that were explicitly provided.
     formatted_target = target_python.format_given()

src/pip/_internal/index/package_finder.py

@@ -198,7 +198,7 @@ def evaluate_link(self, link: Link) -> Tuple[LinkType, str]:
                     reason = f"wrong project name (not {self.project_name})"
                     return (LinkType.different_project, reason)
 
-                supported_tags = self._target_python.get_tags()
+                supported_tags = self._target_python.get_unsorted_tags()
                 if not wheel.supported(supported_tags):
                     # Include the wheel's tags in the reason string to
                     # simplify troubleshooting compatibility issues.
@@ -414,7 +414,7 @@ def create(
         if specifier is None:
             specifier = specifiers.SpecifierSet()
 
-        supported_tags = target_python.get_tags()
+        supported_tags = target_python.get_sorted_tags()
 
         return cls(
             project_name=project_name,

src/pip/_internal/models/target_python.py

@@ -1,5 +1,5 @@
 import sys
-from typing import List, Optional, Tuple
+from typing import List, Optional, Set, Tuple
 
 from pip._vendor.packaging.tags import Tag
 
@@ -22,6 +22,7 @@ class TargetPython:
         "py_version",
         "py_version_info",
         "_valid_tags",
+        "_valid_tags_set",
     ]
 
     def __init__(
@@ -61,8 +62,9 @@ def __init__(
         self.py_version = py_version
         self.py_version_info = py_version_info
 
-        # This is used to cache the return value of get_tags().
+        # This is used to cache the return value of get_(un)sorted_tags.
         self._valid_tags: Optional[List[Tag]] = None
+        self._valid_tags_set: Optional[Set[Tag]] = None
 
     def format_given(self) -> str:
         """
@@ -84,7 +86,7 @@ def format_given(self) -> str:
             f"{key}={value!r}" for key, value in key_values if value is not None
         )
 
-    def get_tags(self) -> List[Tag]:
+    def get_sorted_tags(self) -> List[Tag]:
         """
         Return the supported PEP 425 tags to check wheel candidates against.
 
@@ -108,3 +110,13 @@ def get_tags(self) -> List[Tag]:
             self._valid_tags = tags
 
         return self._valid_tags
+
+    def get_unsorted_tags(self) -> Set[Tag]:
+        """Exactly the same as get_sorted_tags, but returns a set.
+
+        This is important for performance.
+        """
+        if self._valid_tags_set is None:
+            self._valid_tags_set = set(self.get_sorted_tags())
+
+        return self._valid_tags_set

src/pip/_internal/resolution/resolvelib/factory.py

@@ -132,7 +132,7 @@ def _fail_if_link_is_unsupported_wheel(self, link: Link) -> None:
         if not link.is_wheel:
             return
         wheel = Wheel(link.filename)
-        if wheel.supported(self._finder.target_python.get_tags()):
+        if wheel.supported(self._finder.target_python.get_unsorted_tags()):
             return
         msg = f"{link.filename} is not a supported wheel on this platform."
         raise UnsupportedWheel(msg)

tests/unit/test_target_python.py

@@ -88,12 +88,12 @@ def test_format_given(self, kwargs: Dict[str, Any], expected: str) -> None:
             ((3, 7, 3), "37"),
             # Check a minor version with two digits.
             ((3, 10, 1), "310"),
-            # Check that versions=None is passed to get_tags().
+            # Check that versions=None is passed to get_sorted_tags().
             (None, None),
         ],
     )
     @mock.patch("pip._internal.models.target_python.get_supported")
-    def test_get_tags(
+    def test_get_sorted_tags(
         self,
         mock_get_supported: mock.Mock,
         py_version_info: Optional[Tuple[int, ...]],
@@ -102,7 +102,7 @@ def test_get_tags(
         mock_get_supported.return_value = ["tag-1", "tag-2"]
 
         target_python = TargetPython(py_version_info=py_version_info)
-        actual = target_python.get_tags()
+        actual = target_python.get_sorted_tags()
         assert actual == ["tag-1", "tag-2"]
 
         actual = mock_get_supported.call_args[1]["version"]
@@ -111,14 +111,14 @@ def test_get_tags(
         # Check that the value was cached.
         assert target_python._valid_tags == ["tag-1", "tag-2"]
 
-    def test_get_tags__uses_cached_value(self) -> None:
+    def test_get_unsorted_tags__uses_cached_value(self) -> None:
         """
-        Test that get_tags() uses the cached value.
+        Test that get_unsorted_tags() uses the cached value.
         """
         target_python = TargetPython(py_version_info=None)
-        target_python._valid_tags = [
+        target_python._valid_tags_set = {
             Tag("py2", "none", "any"),
             Tag("py3", "none", "any"),
-        ]
-        actual = target_python.get_tags()
-        assert actual == [Tag("py2", "none", "any"), Tag("py3", "none", "any")]
+        }
+        actual = target_python.get_unsorted_tags()
+        assert actual == {Tag("py2", "none", "any"), Tag("py3", "none", "any")}