second commit

venv/Lib/site-packages/trio/_subprocess_platform/kqueue.py

@@ -0,0 +1,41 @@
+import sys
+import select
+from typing import TYPE_CHECKING
+from .. import _core, _subprocess
+
+assert (sys.platform != "win32" and sys.platform != "linux") or not TYPE_CHECKING
+
+
+async def wait_child_exiting(process: "_subprocess.Process") -> None:
+    kqueue = _core.current_kqueue()
+    try:
+        from select import KQ_NOTE_EXIT
+    except ImportError:  # pragma: no cover
+        # pypy doesn't define KQ_NOTE_EXIT:
+        # https://bitbucket.org/pypy/pypy/issues/2921/
+        # I verified this value against both Darwin and FreeBSD
+        KQ_NOTE_EXIT = 0x80000000
+
+    make_event = lambda flags: select.kevent(
+        process.pid, filter=select.KQ_FILTER_PROC, flags=flags, fflags=KQ_NOTE_EXIT
+    )
+
+    try:
+        kqueue.control([make_event(select.KQ_EV_ADD | select.KQ_EV_ONESHOT)], 0)
+    except ProcessLookupError:  # pragma: no cover
+        # This can supposedly happen if the process is in the process
+        # of exiting, and it can even be the case that kqueue says the
+        # process doesn't exist before waitpid(WNOHANG) says it hasn't
+        # exited yet. See the discussion in https://chromium.googlesource.com/
+        # chromium/src/base/+/master/process/kill_mac.cc .
+        # We haven't actually seen this error occur since we added
+        # locking to prevent multiple calls to wait_child_exiting()
+        # for the same process simultaneously, but given the explanation
+        # in Chromium it seems we should still keep the check.
+        return
+
+    def abort(_):
+        kqueue.control([make_event(select.KQ_EV_DELETE)], 0)
+        return _core.Abort.SUCCEEDED
+
+    await _core.wait_kevent(process.pid, select.KQ_FILTER_PROC, abort)