Create session views of the build wheel/sdist into temp_dir (#2614)

Resolves https://github.com/tox-dev/tox/issues/2612

4 files changed, 58 insertions, 6 deletions

diff --git a/src/tox/config/sets.py b/src/tox/config/sets.py
index c87701f8..0315369a 100644
--- a/src/tox/config/sets.py
+++ b/src/tox/config/sets.py
@@ -199,8 +199,8 @@ class CoreConfigSet(ConfigSet):
         self.add_config(
             keys=["temp_dir"],
             of_type=Path,
-            default=lambda conf, _: cast(Path, self["tox_root"]) / ".tmp",  # noqa: U100, U101
-            desc="temporary directory cleaned at start",
+            default=lambda conf, _: cast(Path, self["work_dir"]) / ".tmp",  # noqa: U100, U101
+            desc="a folder for temporary files (is not cleaned at start)",
         )
 
     def _on_duplicate_conf(self, key: str, definition: ConfigDefinition[V]) -> None:  # noqa: U100
diff --git a/src/tox/tox_env/python/virtual_env/package/pyproject.py b/src/tox/tox_env/python/virtual_env/package/pyproject.py
index b9255c1c..de3a81c5 100644
--- a/src/tox/tox_env/python/virtual_env/package/pyproject.py
+++ b/src/tox/tox_env/python/virtual_env/package/pyproject.py
@@ -30,6 +30,7 @@ from tox.tox_env.python.package import (
 )
 from tox.tox_env.register import ToxEnvRegister
 from tox.tox_env.runner import RunToxEnv
+from tox.util.file_view import create_session_view
 
 from ..api import VirtualEnv
 from .util import dependencies_with_extras
@@ -99,6 +100,7 @@ class Pep517VirtualEnvPackager(PythonPackageToxEnv, VirtualEnv):
         self._package_name: str | None = None
         self._pkg_lock = RLock()  # can build only one package at a time
         self.root = self.conf["package_root"]
+        self._package_paths: set[Path] = set()
 
     @staticmethod
     def id() -> str:
@@ -164,6 +166,10 @@ class Pep517VirtualEnvPackager(PythonPackageToxEnv, VirtualEnv):
                 pass
             finally:
                 executor.close()
+        for path in self._package_paths:
+            if path.exists():
+                logging.debug("delete package %s", path)
+                path.unlink()
         super()._teardown()
 
     def perform_packaging(self, for_env: EnvConfigSet) -> list[Package]:
@@ -189,7 +195,10 @@ class Pep517VirtualEnvPackager(PythonPackageToxEnv, VirtualEnv):
         elif of_type == "sdist":
             self.setup()
             with self._pkg_lock:
-                package = SdistPackage(self._frontend.build_sdist(sdist_directory=self.pkg_dir).sdist, deps)
+                sdist = self._frontend.build_sdist(sdist_directory=self.pkg_dir).sdist
+                sdist = create_session_view(sdist, self._package_temp_path)
+                self._package_paths.add(sdist)
+                package = SdistPackage(sdist, deps)
         elif of_type in {"wheel", "editable"}:
             w_env = self._wheel_build_envs.get(for_env["wheel_build_env"])
             if w_env is not None and w_env is not self:
@@ -199,16 +208,22 @@ class Pep517VirtualEnvPackager(PythonPackageToxEnv, VirtualEnv):
                 self.setup()
                 method = "build_editable" if of_type == "editable" else "build_wheel"
                 with self._pkg_lock:
-                    path = getattr(self._frontend, method)(
+                    wheel = getattr(self._frontend, method)(
                         wheel_directory=self.pkg_dir,
                         metadata_directory=self.meta_folder,
                         config_settings=self._wheel_config_settings,
                     ).wheel
-                package = (EditablePackage if of_type == "editable" else WheelPackage)(path, deps)
+                    wheel = create_session_view(wheel, self._package_temp_path)
+                    self._package_paths.add(wheel)
+                package = (EditablePackage if of_type == "editable" else WheelPackage)(wheel, deps)
         else:  # pragma: no cover # for when we introduce new packaging types and don't implement
             raise TypeError(f"cannot handle package type {of_type}")  # pragma: no cover
         return [package]
 
+    @property
+    def _package_temp_path(self) -> Path:
+        return cast(Path, self.core["temp_dir"]) / "package"
+
     def _load_deps(self, for_env: EnvConfigSet) -> list[Requirement]:
         # first check if this is statically available via PEP-621
         deps = self._load_deps_from_static(for_env)
diff --git a/src/tox/tox_env/python/virtual_env/package/util.py b/src/tox/tox_env/python/virtual_env/package/util.py
index 9936c7f2..5139e7ba 100644
--- a/src/tox/tox_env/python/virtual_env/package/util.py
+++ b/src/tox/tox_env/python/virtual_env/package/util.py
@@ -2,7 +2,7 @@ from __future__ import annotations
 
 from copy import deepcopy
 
-from packaging.markers import Variable
+from packaging.markers import Variable  # type: ignore[attr-defined]
 from packaging.requirements import Requirement
 
 
diff --git a/src/tox/util/file_view.py b/src/tox/util/file_view.py
new file mode 100644
index 00000000..488d9aa8
--- /dev/null
+++ b/src/tox/util/file_view.py
@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+import logging
+import os
+import shutil
+from itertools import chain
+from os.path import commonpath
+from pathlib import Path
+
+
+def create_session_view(package: Path, temp_path: Path) -> Path:
+    """Allows using the file after you no longer holding a lock to it by moving it into a temp folder"""
+    # we'll number the active instances, and use the max value as session folder for a new build
+    # note we cannot change package names as PEP-491 (wheel binary format)
+    # is strict about file name structure
+
+    temp_path.mkdir(parents=True, exist_ok=True)
+    exists = [i.name for i in temp_path.iterdir()]
+    file_id = max(chain((0,), (int(i) for i in exists if str(i).isnumeric())))
+    session_dir = temp_path / str(file_id + 1)
+    session_dir.mkdir()
+    session_package = session_dir / package.name
+
+    links = False  # if we can do hard links do that, otherwise just copy
+    if hasattr(os, "link"):
+        try:
+            os.link(package, session_package)
+            links = True
+        except (OSError, NotImplementedError):
+            pass
+    if not links:
+        shutil.copyfile(package, session_package)
+    operation = "links" if links else "copied"
+    common = commonpath((session_package, package))
+    rel_session, rel_package = session_package.relative_to(common), package.relative_to(common)
+    logging.debug("package %s %s to %s (%s)", rel_session, operation, rel_package, common)
+    return session_package