dep: move Dep caching support into CachedDep class

That provides LRU-based instance caching for Dep objects.

benches/test_dep.py

@@ -2,6 +2,7 @@
 from pkgcore.ebuild.atom import atom as pkgcore_dep
 from portage.dep import Atom as portage_dep
 
+from pkgcraft.dep import CachedDep as pkgcraft_cached_dep
 from pkgcraft.dep import Dep as pkgcraft_dep
 
 pytest_plugins = ("benchmark", "pkgcraft")
@@ -16,7 +17,7 @@ def random_dep(func, random_str):
 
 dep_funcs = [
     ("pkgcraft", pkgcraft_dep),
-    ("pkgcraft", pkgcraft_dep.cached),
+    ("pkgcraft", pkgcraft_cached_dep),
     ("pkgcore", pkgcore_dep),
     ("portage", portage_dep),
 ]

membench/dep.py

@@ -11,13 +11,13 @@
 from pkgcore.ebuild.atom import atom as pkgcore_dep
 from portage.dep import Atom as portage_dep
 
-from pkgcraft.dep import Dep as pkgcraft_dep
+from pkgcraft.dep import CachedDep, Dep
 
 eprint = lambda x: print(x, file=sys.stderr)
 
 dep_funcs = [
-    ("pkgcraft", pkgcraft_dep),
-    ("pkgcraft-cached", pkgcraft_dep.cached),
+    ("pkgcraft", Dep),
+    ("pkgcraft-cached", CachedDep),
     ("pkgcore", pkgcore_dep),
     ("portage", portage_dep),
 ]

src/pkgcraft/dep/pkg.pyx

@@ -1,5 +1,4 @@
 from enum import IntEnum
-from functools import lru_cache
 from types import MappingProxyType
 
 cimport cython
@@ -12,18 +11,12 @@ from ..restrict cimport Restrict
 from . cimport Cpv
 from .version cimport Version
 
+from .._misc import LruInstanceCache
 from ..eapi import EAPI_LATEST
 from ..error import InvalidDep
 from ..types import OrderedFrozenSet
 
 
-# TODO: merge with Dep.cached function when cython bug is fixed
-# https://github.com/cython/cython/issues/1434
-@lru_cache(maxsize=10000)
-def _cached_dep(cls, dep, eapi=None):
-    return cls(dep, eapi)
-
-
 class Blocker(IntEnum):
     """Package dependency blocker."""
     Strong = C.BLOCKER_STRONG
@@ -125,11 +118,6 @@ cdef class Dep:
         inst.ptr = <C.Dep *>ptr
         return inst
 
-    @classmethod
-    def cached(cls, s: str, eapi=None):
-        """Return a cached Dep if one exists, otherwise return a new instance."""
-        return _cached_dep(cls, s, eapi)
-
     @staticmethod
     def valid(s: str, eapi=None, raised=False):
         """Determine if a string is a valid package dependency.
@@ -618,6 +606,10 @@ cdef class Dep:
         C.pkgcraft_dep_free(self.ptr)
 
 
+class CachedDep(Dep, metaclass=LruInstanceCache):
+    """Package dependency with LRU-based instance caching."""
+
+
 @cython.final
 cdef class Cpn(Dep):
     """Unversioned package dependency."""

tests/dep/test_pkg.py

@@ -355,16 +355,18 @@ def test_hash(self):
             length = 1 if d["equal"] else len(d["versions"])
             assert len(s) == length
 
-    def test_cached(self):
-        l = [Dep.cached("cat/pkg") for _ in range(1000)]
-        assert len(l) == 1000
-
     def test_pickle(self):
         dep = Dep("=cat/pkg-1-r2:0/2=[a,b,c]")
         new_dep = pickle.loads(pickle.dumps(dep))
         assert dep == new_dep
 
 
+class TestCachedDep:
+    def test_cached(self):
+        assert CachedDep("cat/pkg") is CachedDep("cat/pkg")
+        assert Dep("cat/pkg") is not Dep("cat/pkg")
+
+
 class TestCpn:
     def test_creation(self):
         dep = Cpn("cat/pkg")