Major fixes and new features

venv/lib/python3.12/site-packages/coverage/multiproc.py

@@ -0,0 +1,120 @@
+# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
+# For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt
+
+"""Monkey-patching to add multiprocessing support for coverage.py"""
+
+from __future__ import annotations
+
+import multiprocessing
+import multiprocessing.process
+import os
+import os.path
+import sys
+import traceback
+from typing import Any
+
+from coverage.debug import DebugControl
+
+# An attribute that will be set on the module to indicate that it has been
+# monkey-patched.
+PATCHED_MARKER = "_coverage$patched"
+
+
+OriginalProcess = multiprocessing.process.BaseProcess
+original_bootstrap = OriginalProcess._bootstrap  # type: ignore[attr-defined]
+
+
+class ProcessWithCoverage(OriginalProcess):  # pylint: disable=abstract-method
+    """A replacement for multiprocess.Process that starts coverage."""
+
+    def _bootstrap(self, *args, **kwargs):  # type: ignore[no-untyped-def]
+        """Wrapper around _bootstrap to start coverage."""
+        debug: DebugControl | None = None
+        try:
+            from coverage import Coverage  # avoid circular import
+
+            cov = Coverage(data_suffix=True, auto_data=True)
+            cov._warn_preimported_source = False
+            cov.start()
+            _debug = cov._debug
+            assert _debug is not None
+            if _debug.should("multiproc"):
+                debug = _debug
+            if debug:
+                debug.write("Calling multiprocessing bootstrap")
+        except Exception:
+            print("Exception during multiprocessing bootstrap init:", file=sys.stderr)
+            traceback.print_exc(file=sys.stderr)
+            sys.stderr.flush()
+            raise
+        try:
+            return original_bootstrap(self, *args, **kwargs)
+        finally:
+            if debug:
+                debug.write("Finished multiprocessing bootstrap")
+            try:
+                cov.stop()
+                cov.save()
+            except Exception as exc:
+                if debug:
+                    debug.write("Exception during multiprocessing bootstrap cleanup", exc=exc)
+                raise
+            if debug:
+                debug.write("Saved multiprocessing data")
+
+
+class Stowaway:
+    """An object to pickle, so when it is unpickled, it can apply the monkey-patch."""
+
+    def __init__(self, rcfile: str) -> None:
+        self.rcfile = rcfile
+
+    def __getstate__(self) -> dict[str, str]:
+        return {"rcfile": self.rcfile}
+
+    def __setstate__(self, state: dict[str, str]) -> None:
+        patch_multiprocessing(state["rcfile"])
+
+
+def patch_multiprocessing(rcfile: str) -> None:
+    """Monkey-patch the multiprocessing module.
+
+    This enables coverage measurement of processes started by multiprocessing.
+    This involves aggressive monkey-patching.
+
+    `rcfile` is the path to the rcfile being used.
+
+    """
+
+    if hasattr(multiprocessing, PATCHED_MARKER):
+        return
+
+    OriginalProcess._bootstrap = ProcessWithCoverage._bootstrap  # type: ignore[attr-defined]
+
+    # Set the value in ProcessWithCoverage that will be pickled into the child
+    # process.
+    os.environ["COVERAGE_RCFILE"] = os.path.abspath(rcfile)
+
+    # When spawning processes rather than forking them, we have no state in the
+    # new process.  We sneak in there with a Stowaway: we stuff one of our own
+    # objects into the data that gets pickled and sent to the subprocess. When
+    # the Stowaway is unpickled, its __setstate__ method is called, which
+    # re-applies the monkey-patch.
+    # Windows only spawns, so this is needed to keep Windows working.
+    try:
+        from multiprocessing import spawn
+
+        original_get_preparation_data = spawn.get_preparation_data
+    except (ImportError, AttributeError):
+        pass
+    else:
+
+        def get_preparation_data_with_stowaway(name: str) -> dict[str, Any]:
+            """Get the original preparation data, and also insert our stowaway."""
+            d = original_get_preparation_data(name)
+            d["stowaway"] = Stowaway(rcfile)
+            return d
+
+        spawn.get_preparation_data = get_preparation_data_with_stowaway
+
+    setattr(multiprocessing, PATCHED_MARKER, True)