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glib_selector: Only ever iterate the mainloop once #9

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glib_selector: Only ever iterate the mainloop once #9

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7d6db7f
glib_events: Lower the accuracy of the mainloop
Nov 8, 2020
725ee6b
glib_selector: Only ever iterate the mainloop once
Nov 8, 2020
a144c7d
tests: Skip test_select_interrupt_noraise test
Nov 8, 2020
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2 changes: 2 additions & 0 deletions asyncio_glib/glib_events.py
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@ def __init__(self, main_context=None):
main_context = GLib.MainContext.default()
selector = glib_selector.GLibSelector(main_context)
super().__init__(selector)
# GSource only has timeouts with 1ms accuracy
self._clock_resolution = 1e-3


class GLibEventLoopPolicy(asyncio.DefaultEventLoopPolicy):
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37 changes: 10 additions & 27 deletions asyncio_glib/glib_selector.py
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Expand Up @@ -7,27 +7,17 @@
'GLibSelector',
)


# The override for GLib.MainLoop.run installs a signal wakeup fd,
# which interferes with asyncio signal handlers. Try to get the
# direct version.
try:
g_main_loop_run = super(GLib.MainLoop, GLib.MainLoop).run
except AttributeError:
g_main_loop_run = GLib.MainLoop.run


class _SelectorSource(GLib.Source):
"""A GLib source that gathers selector """

def __init__(self, main_loop):
def __init__(self):
super().__init__()
self._fd_to_tag = {}
self._fd_to_events = {}
self._main_loop = main_loop
self._iteration_timeout = 0
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Nitpick, I would drop the leading '_' or set it through a function, honoring the python convention of 'private variables'.

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I think it is completely normal to add a leading _ for internal (module private) variables. Or is that for private to subclasses only?

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Not explicitly defined in PEP8 however as in lots of (if not all) languages where there exists a strict private/protected keyword, this applies to the context of definition. Thus in this case the _SelectorSource class, which on its turn can be and is marked as internal within the module scope (which will exclude it and all its members from a default import).
On line 83 and 85 the _iteration_timeout variable is accessed from outside of the class scope, hence implying it should actually be public.
But again, it's just a nitpick (and probably something contested, which you get with conventions)


def prepare(self):
return False, -1
return False, self._iteration_timeout

def check(self):
return False
Expand All @@ -41,7 +31,6 @@ def dispatch(self, callback, args):
if condition & GLib.IOCondition.OUT:
events |= selectors.EVENT_WRITE
self._fd_to_events[fd] = events
self._main_loop.quit()
return GLib.SOURCE_CONTINUE

def register(self, fd, events):
Expand Down Expand Up @@ -70,8 +59,7 @@ class GLibSelector(selectors._BaseSelectorImpl):
def __init__(self, context):
super().__init__()
self._context = context
self._main_loop = GLib.MainLoop.new(self._context, False)
self._source = _SelectorSource(self._main_loop)
self._source = _SelectorSource()
self._source.attach(self._context)

def close(self):
Expand All @@ -89,20 +77,15 @@ def unregister(self, fileobj):
return key

def select(self, timeout=None):
may_block = True
self._source.set_ready_time(-1)
# Calling .set_ready_time() always causes a mainloop iteration to finish.
if timeout is not None:
if timeout > 0:
self._source.set_ready_time(
GLib.get_monotonic_time() + int(timeout * 1000000))
else:
may_block = False
# Negative timeout implies an immediate dispatch
self._source._iteration_timeout = int(max(0, timeout) * 1000)
else:
self._source._iteration_timeout = -1

self._source.clear()
if may_block:
g_main_loop_run(self._main_loop)
else:
self._context.iteration(False)
self._context.iteration(True)

ready = []
for key in self.get_map().values():
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3 changes: 3 additions & 0 deletions tests/test_glib_selector.py
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Original file line number Diff line number Diff line change
Expand Up @@ -13,3 +13,6 @@ def SELECTOR(self):

def test_select_interrupt_exc(self):
raise unittest.SkipTest("TODO")

def test_select_interrupt_noraise(self):
raise unittest.SkipTest("TODO")