Optimize Target and FieldSet operations (pantsbuild#18917)

Recent profiles (from pantsbuild#18911, and reproduced locally) highlighted:
* `FieldSet.create` was repeatedly calling the unmemoized
`_get_field_set_fields`, which used the surprisingly expensive `from
typing import get_type_hints`.
    * This change moves type hint extraction into a memoized property.
* `Target.has_fields` was doing an N^2 lookup of fields in a computed
collection of registered fields.
* Moved to using the `field_values` `dict` to represent the set of
present fields, and removed the `plugin_fields` property (which is
always incorporated into the `field_values` at construction time
anyway).

----

Performance for `./pants --no-pantsd dependencies ::` in
`pantsbuild/pants` improves by 9% (or 15%, if the time for rule graph
solving is ignored).

src/python/pants/backend/docker/goals/package_image_test.py

@@ -954,13 +954,13 @@ def check_docker_proc(process: Process):
         assert process.argv == (
             "/dummy/docker",
             "build",
+            "--pull=False",
             "--secret",
             "id=system-secret,src=/var/run/secrets/mysecret",
             "--secret",
             f"id=project-secret,src={rule_runner.build_root}/secrets/mysecret",
             "--secret",
             f"id=target-secret,src={rule_runner.build_root}/docker/test/mysecret",
-            "--pull=False",
             "--tag",
             "img1:latest",
             "--file",
@@ -993,9 +993,9 @@ def check_docker_proc(process: Process):
         assert process.argv == (
             "/dummy/docker",
             "build",
+            "--pull=False",
             "--ssh",
             "default",
-            "--pull=False",
             "--tag",
             "img1:latest",
             "--file",

src/python/pants/core/util_rules/partitions.py

@@ -17,13 +17,7 @@
 from pants.engine.engine_aware import EngineAwareParameter
 from pants.engine.internals.selectors import Get, MultiGet
 from pants.engine.rules import collect_rules, rule
-from pants.engine.target import (
-    FieldSet,
-    SourcesField,
-    SourcesPaths,
-    SourcesPathsRequest,
-    _get_field_set_fields,
-)
+from pants.engine.target import FieldSet, SourcesField, SourcesPaths, SourcesPathsRequest
 from pants.util.memo import memoized
 from pants.util.meta import runtime_ignore_subscripts
 
@@ -317,7 +311,7 @@ def _get_sources_field_name(field_set_type: type[FieldSet]) -> str:
     """
 
     sources_field_name = None
-    for fieldname, fieldtype in _get_field_set_fields(field_set_type).items():
+    for fieldname, fieldtype in field_set_type.fields.items():
         if issubclass(fieldtype, SourcesField):
             if sources_field_name is None:
                 sources_field_name = fieldname

src/python/pants/engine/internals/parser.py

@@ -323,7 +323,11 @@ def create_registrar_for_target(alias: str) -> tuple[str, Registrar]:
             return alias, Registrar(
                 parse_state,
                 alias,
-                registered_target_types.aliases_to_types[alias].class_field_types(union_membership),
+                tuple(
+                    registered_target_types.aliases_to_types[alias].class_field_types(
+                        union_membership
+                    )
+                ),
             )
 
         type_aliases = dict(map(create_registrar_for_target, registered_target_types.aliases))

src/python/pants/engine/target.py

@@ -18,13 +18,15 @@
 from enum import Enum
 from pathlib import PurePath
 from typing import (
+    AbstractSet,
     Any,
     Callable,
     ClassVar,
     Dict,
     Generic,
     Iterable,
     Iterator,
+    KeysView,
     Mapping,
     Optional,
     Sequence,
@@ -62,7 +64,7 @@
 from pants.util.dirutil import fast_relpath
 from pants.util.docutil import bin_name, doc_url
 from pants.util.frozendict import FrozenDict
-from pants.util.memo import memoized_method, memoized_property
+from pants.util.memo import memoized_classproperty, memoized_method, memoized_property
 from pants.util.ordered_set import FrozenOrderedSet
 from pants.util.strutil import bullet_list, help_text, pluralize, softwrap
 
@@ -379,7 +381,6 @@ class Target:
 
     # These get calculated in the constructor
     address: Address
-    plugin_fields: tuple[type[Field], ...]
     field_values: FrozenDict[type[Field], Field]
     residence_dir: str
     name_explicitly_set: bool
@@ -439,7 +440,7 @@ def __init__(
             self,
             "field_values",
             self._calculate_field_values(
-                unhydrated_values, address, ignore_unrecognized_fields=ignore_unrecognized_fields
+                unhydrated_values, address, union_membership, ignore_unrecognized_fields=ignore_unrecognized_fields
             ),
         )
 
@@ -450,11 +451,14 @@ def _calculate_field_values(
         self,
         unhydrated_values: dict[str, Any],
         address: Address,
+        # See `__init__`.
+        union_membership: UnionMembership | None,
         *,
         ignore_unrecognized_fields: bool,
     ) -> FrozenDict[type[Field], Field]:
+        all_field_types = self.class_field_types(union_membership)
         field_values = {}
-        aliases_to_field_types = self._get_field_aliases_to_field_types(self.field_types)
+        aliases_to_field_types = self._get_field_aliases_to_field_types(all_field_types)
 
         for alias, value in unhydrated_values.items():
             if alias not in aliases_to_field_types:
@@ -478,7 +482,9 @@ def _calculate_field_values(
             field_values[field_type] = field_type(value, address)
 
         # For undefined fields, mark the raw value as missing.
-        for field_type in set(self.field_types) - set(field_values.keys()):
+        for field_type in all_field_types:
+            if field_type in field_values:
+                continue
             field_values[field_type] = field_type(NO_VALUE, address)
         return FrozenDict(
             sorted(
@@ -490,7 +496,7 @@ def _calculate_field_values(
     @final
     @classmethod
     def _get_field_aliases_to_field_types(
-        cls, field_types: tuple[type[Field], ...]
+        cls, field_types: Iterable[type[Field]]
     ) -> dict[str, type[Field]]:
         aliases_to_field_types = {}
         for field_type in field_types:
@@ -501,8 +507,8 @@ def _get_field_aliases_to_field_types(
 
     @final
     @property
-    def field_types(self) -> Tuple[Type[Field], ...]:
-        return (*self.core_fields, *self.plugin_fields)
+    def field_types(self) -> KeysView[Type[Field]]:
+        return self.field_values.keys()
 
     @distinct_union_type_per_subclass
     class PluginField:
@@ -538,6 +544,7 @@ def __eq__(self, other: Union[Target, Any]) -> bool:
 
     @final
     @classmethod
+    @memoized_method
     def _find_plugin_fields(cls, union_membership: UnionMembership) -> tuple[type[Field], ...]:
         result: set[type[Field]] = set()
         classes = [cls]
@@ -577,7 +584,7 @@ def _maybe_get(self, field: Type[_F]) -> Optional[_F]:
         if result is not None:
             return cast(_F, result)
         field_subclass = self._find_registered_field_subclass(
-            field, registered_fields=self.field_types
+            field, registered_fields=self.field_values.keys()
         )
         if field_subclass is not None:
             return cast(_F, self.field_values[field_subclass])
@@ -631,7 +638,7 @@ def get(self, field: Type[_F], *, default_raw_value: Optional[Any] = None) -> _F
     @final
     @classmethod
     def _has_fields(
-        cls, fields: Iterable[Type[Field]], *, registered_fields: Iterable[Type[Field]]
+        cls, fields: Iterable[Type[Field]], *, registered_fields: AbstractSet[Type[Field]]
     ) -> bool:
         unrecognized_fields = [field for field in fields if field not in registered_fields]
         if not unrecognized_fields:
@@ -662,17 +669,23 @@ def has_fields(self, fields: Iterable[Type[Field]]) -> bool:
         custom subclass `CustomTags`, both `tgt.has_fields([Tags])` and
         `python_tgt.has_fields([CustomTags])` will return True.
         """
-        return self._has_fields(fields, registered_fields=self.field_types)
+        return self._has_fields(fields, registered_fields=self.field_values.keys())
 
     @final
     @classmethod
-    def class_field_types(cls, union_membership: UnionMembership) -> Tuple[Type[Field], ...]:
+    @memoized_method
+    def class_field_types(
+        cls, union_membership: UnionMembership | None
+    ) -> FrozenOrderedSet[Type[Field]]:
         """Return all registered Fields belonging to this target type.
 
         You can also use the instance property `tgt.field_types` to avoid having to pass the
         parameter UnionMembership.
         """
-        return (*cls.core_fields, *cls._find_plugin_fields(union_membership))
+        if union_membership is None:
+            return FrozenOrderedSet(cls.core_fields)
+        else:
+            return FrozenOrderedSet((*cls.core_fields, *cls._find_plugin_fields(union_membership)))
 
     @final
     @classmethod
@@ -1326,23 +1339,14 @@ def gen_tgt(address: Address, full_fp: str, generated_target_fields: dict[str, A
 # -----------------------------------------------------------------------------------------------
 # FieldSet
 # -----------------------------------------------------------------------------------------------
-def _get_field_set_fields(field_set: Type[FieldSet]) -> Dict[str, Type[Field]]:
-    return {
-        name: field_type
-        for name, field_type in get_type_hints(field_set).items()
-        if isinstance(field_type, type) and issubclass(field_type, Field)
-    }
-
-
 def _get_field_set_fields_from_target(
     field_set: Type[FieldSet], target: Target
 ) -> Dict[str, Field]:
-    all_expected_fields = _get_field_set_fields(field_set)
     return {
         dataclass_field_name: (
             target[field_cls] if field_cls in field_set.required_fields else target.get(field_cls)
         )
-        for dataclass_field_name, field_cls in all_expected_fields.items()
+        for dataclass_field_name, field_cls in field_set.fields.items()
     }
 
 
@@ -1428,6 +1432,17 @@ def applicable_target_types(
     def create(cls: Type[_FS], tgt: Target) -> _FS:
         return cls(address=tgt.address, **_get_field_set_fields_from_target(cls, tgt))
 
+    @final
+    @memoized_classproperty
+    def fields(cls) -> FrozenDict[str, Type[Field]]:
+        return FrozenDict(
+            (
+                (name, field_type)
+                for name, field_type in get_type_hints(cls).items()
+                if isinstance(field_type, type) and issubclass(field_type, Field)
+            )
+        )
+
     def debug_hint(self) -> str:
         return self.address.spec
 

src/python/pants/engine/target_test.py

@@ -216,11 +216,11 @@ def test_has_fields() -> None:
     empty_union_membership = UnionMembership({})
     tgt = FortranTarget({}, Address("", target_name="lib"))
 
-    assert tgt.field_types == (FortranExtensions, FortranVersion)
-    assert FortranTarget.class_field_types(union_membership=empty_union_membership) == (
+    assert tgt.field_types == {FortranExtensions, FortranVersion}
+    assert set(FortranTarget.class_field_types(union_membership=empty_union_membership)) == {
         FortranExtensions,
         FortranVersion,
-    )
+    }
 
     assert tgt.has_fields([]) is True
     assert FortranTarget.class_has_fields([], union_membership=empty_union_membership) is True
@@ -269,16 +269,15 @@ class CustomField(BoolField):
         tgt_values, Address("", target_name="lib"), union_membership=union_membership
     )
 
-    assert tgt.field_types == (FortranExtensions, FortranVersion, CustomField)
+    assert tgt.field_types == {FortranExtensions, FortranVersion, CustomField}
     assert tgt.core_fields == (FortranExtensions, FortranVersion)
-    assert tgt.plugin_fields == (CustomField,)
     assert tgt.has_field(CustomField) is True
 
-    assert FortranTarget.class_field_types(union_membership=union_membership) == (
+    assert set(FortranTarget.class_field_types(union_membership=union_membership)) == {
         FortranExtensions,
         FortranVersion,
         CustomField,
-    )
+    }
     assert FortranTarget.class_has_field(CustomField, union_membership=union_membership) is True
     assert (
         FortranTarget.class_get_field(CustomField, union_membership=union_membership) is CustomField
@@ -297,7 +296,7 @@ class OtherTarget(Target):
         core_fields = ()
 
     other_tgt = OtherTarget({}, Address("", target_name="other"))
-    assert other_tgt.plugin_fields == ()
+    assert tuple(other_tgt.field_types) == ()
     assert other_tgt.has_field(CustomField) is False