Merge branch 'bugfixes/16-EINVAL-during-bus-transition'

magicbus/base.py

@@ -10,6 +10,7 @@
 are free to define their own channels. If a message is sent to a
 channel that has not been defined or has no listeners, there is no effect.
 """
+import errno
 import os
 import random
 try:
@@ -202,7 +203,23 @@ def _transition(self, newstate, *args, **kwargs):
             # Write to any pipes created by threads calling self.wait().
             # Use list() to avoid "Set changed size during iteration" errors.
             for read_fd, write_fd in list(self._state_transition_pipes):
-                os.write(write_fd, b'1')
+                try:
+                    os.write(write_fd, b'1')
+                except OSError as os_err_exc:
+                    # Ref: https://github.com/cherrypy/magicbus/issues/16
+                    #
+                    # NOTE: This is supposedly happening when `self.wait()`
+                    # NOTE: closes the pipe on disposal.
+                    if os_err_exc.errno not in {
+                        # NOTE: This has been noticed in CI under both
+                        # NOTE: Ubuntu and Windows:
+                        errno.EBADF,
+
+                        # NOTE: This behavior is currently only observed
+                        # NOTE: under Windows in GHA CI/CD workflows:
+                        errno.EINVAL,
+                    }:
+                        raise
 
             # Note: logging here means 1) the initial transition
             # will not be logged if loggers are set up in the initial
@@ -335,8 +352,10 @@ def _wait():
                     self.publish(channel)
             finally:
                 self._state_transition_pipes.discard(pipe)
-                os.close(read_fd)
+                # NOTE: Closing the write file descriptor first
+                # NOTE: to prevent "Broken pipe" in `self._transition()`.
                 os.close(write_fd)
+                os.close(read_fd)
 
         # From http://psyco.sourceforge.net/psycoguide/bugs.html:
         # "The compiled machine code does not include the regular polling

magicbus/test/test_processbus.py

@@ -203,17 +203,6 @@ def test_idle_to_exit(self):
             'Bus state: EXITED'
         ])
 
-    @pytest.mark.xfail(
-        reason=r"""Fails intermittently with
-        Traceback (most recent call last):
-        File "D:\a\magicbus\magicbus\magicbus\base.py",
-             line 205, in _transition
-        os.write(write_fd, b'1')
-        OSError: [Errno 22] Invalid argument
-        """,
-        raises=AssertionError,
-        strict=False,  # Because it's flaky
-    )
     def test_wait(self):
         b = ProcessBus()
         self.log(b)