proj/pkgcore/snakeoil:master commit in: /, src/snakeoil/klass/

commit:     9ea8b9d99bf77a8b7cffc9a1c3cba8abafd9b9ec
Author:     Arthur Zamarin <arthurzam <AT> gentoo <DOT> org>
AuthorDate: Fri Aug  7 21:20:09 2026 +0000
Commit:     Arthur Zamarin <arthurzam <AT> gentoo <DOT> org>
CommitDate: Fri Aug  7 21:20:09 2026 +0000
URL:        https://gitweb.gentoo.org/proj/pkgcore/snakeoil.git/commit/?id=9ea8b9d9

klass.immutable: inline the mutation block into the autowrapper

__allow_mutation_wrapper__ entered __allow_mutation__ via `with`, so every
auto wrapped __init__ built a generator, drove it through __enter__ and
__exit__, and tore it down - all to set one contextvar and reset it. Do
that directly in the wrapper instead. __allow_mutation__ itself is
untouched and still the way to open a mutation block by hand; nothing
overrides it, so the wrapper was it's only caller.

Semantics are identical: same contextvar, same id(instance), same reset in
a finally. Construction of small immutable instances gets cheaper, the
saving being a fixed cost per call rather than per attribute:

    StrExactMatch            0.047s -> 0.031s   1.53x
    PackageRestriction       0.128s -> 0.111s   1.16x
    atom                     0.212s -> 0.195s   1.09x
    19602 restriction trees  0.270s -> 0.236s   1.15x

Signed-off-by: Arthur Zamarin <arthurzam <AT> gentoo.org>

 NEWS.rst                        | 4 ++++
 src/snakeoil/klass/immutable.py | 7 ++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/NEWS.rst b/NEWS.rst
index 9898052..556a36d 100644
--- a/NEWS.rst
+++ b/NEWS.rst
@@ -23,6 +23,10 @@ snakeoil 0.11.4 (unreleased)
   serialization.  Dropping it makes serializing slotted objects ~4x faster
   (Arthur Zamarin, #117)
 
+- ``snakeoil.klass.immutable.Simple``: methods auto wrapped in a mutation block
+  no longer build and drive a ``@contextmanager`` generator per call.  Creating
+  small immutable instances is up to 1.5x faster (Arthur Zamarin)
+
 
 snakeoil 0.11.3 (2026-07-30)
 ----------------------------

diff --git a/src/snakeoil/klass/immutable.py b/src/snakeoil/klass/immutable.py
index 8d0c972..e47d967 100644
--- a/src/snakeoil/klass/immutable.py
+++ b/src/snakeoil/klass/immutable.py
@@ -122,8 +122,13 @@ class Simple:
     def __allow_mutation_wrapper__(cls, functor):
         @functools.wraps(functor)
         def f(instance, *args, **kwargs):
-            with cls.__allow_mutation__(instance):
+            # __allow_mutation__ inlined; building and driving it's generator is
+            # the dominant cost of creating small immutable instances.
+            last = _immutable_allow_mutations.set(id(instance))
+            try:
                 return functor(instance, *args, **kwargs)
+            finally:
+                _immutable_allow_mutations.reset(last)
 
         f.__disable_mutation_autowrapping__ = True  # pyright: ignore[reportAttributeAccessIssue] # it's already wrapped.
         return f