Current File : //snap/core20/current/lib/python3/dist-packages/urwid/main_loop.py
#!/usr/bin/python
#
# Urwid main loop code
# Copyright (C) 2004-2012 Ian Ward
# Copyright (C) 2008 Walter Mundt
# Copyright (C) 2009 Andrew Psaltis
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# Urwid web site: http://excess.org/urwid/
from __future__ import division, print_function
import time
import heapq
import select
import os
import signal
from functools import wraps
from itertools import count
from weakref import WeakKeyDictionary
try:
import fcntl
except ImportError:
pass # windows
from urwid.util import StoppingContext, is_mouse_event
from urwid.compat import PYTHON3, reraise
from urwid.command_map import command_map, REDRAW_SCREEN
from urwid.wimp import PopUpTarget
from urwid import signals
from urwid.display_common import INPUT_DESCRIPTORS_CHANGED
PIPE_BUFFER_READ_SIZE = 4096 # can expect this much on Linux, so try for that
class ExitMainLoop(Exception):
"""
When this exception is raised within a main loop the main loop
will exit cleanly.
"""
pass
class CantUseExternalLoop(Exception):
pass
class MainLoop(object):
"""
This is the standard main loop implementation for a single interactive
session.
:param widget: the topmost widget used for painting the screen, stored as
:attr:`widget` and may be modified. Must be a box widget.
:type widget: widget instance
:param palette: initial palette for screen
:type palette: iterable of palette entries
:param screen: screen to use, default is a new :class:`raw_display.Screen`
instance; stored as :attr:`screen`
:type screen: display module screen instance
:param handle_mouse: ``True`` to ask :attr:`.screen` to process mouse events
:type handle_mouse: bool
:param input_filter: a function to filter input before sending it to
:attr:`.widget`, called from :meth:`.input_filter`
:type input_filter: callable
:param unhandled_input: a function called when input is not handled by
:attr:`.widget`, called from :meth:`.unhandled_input`
:type unhandled_input: callable
:param event_loop: if :attr:`.screen` supports external an event loop it may be
given here, default is a new :class:`SelectEventLoop` instance;
stored as :attr:`.event_loop`
:type event_loop: event loop instance
:param pop_ups: `True` to wrap :attr:`.widget` with a :class:`PopUpTarget`
instance to allow any widget to open a pop-up anywhere on the screen
:type pop_ups: boolean
.. attribute:: screen
The screen object this main loop uses for screen updates and reading input
.. attribute:: event_loop
The event loop object this main loop uses for waiting on alarms and IO
"""
def __init__(self, widget, palette=(), screen=None,
handle_mouse=True, input_filter=None, unhandled_input=None,
event_loop=None, pop_ups=False):
self._widget = widget
self.handle_mouse = handle_mouse
self.pop_ups = pop_ups # triggers property setting side-effect
if not screen:
from urwid import raw_display
screen = raw_display.Screen()
if palette:
screen.register_palette(palette)
self.screen = screen
self.screen_size = None
self._unhandled_input = unhandled_input
self._input_filter = input_filter
if not hasattr(screen, 'hook_event_loop'
) and event_loop is not None:
raise NotImplementedError("screen object passed "
"%r does not support external event loops" % (screen,))
if event_loop is None:
event_loop = SelectEventLoop()
self.event_loop = event_loop
if hasattr(self.screen, 'signal_handler_setter'):
# Tell the screen what function it must use to set
# signal handlers
self.screen.signal_handler_setter = self.event_loop.set_signal_handler
self._watch_pipes = {}
def _set_widget(self, widget):
self._widget = widget
if self.pop_ups:
self._topmost_widget.original_widget = self._widget
else:
self._topmost_widget = self._widget
widget = property(lambda self:self._widget, _set_widget, doc=
"""
Property for the topmost widget used to draw the screen.
This must be a box widget.
""")
def _set_pop_ups(self, pop_ups):
self._pop_ups = pop_ups
if pop_ups:
self._topmost_widget = PopUpTarget(self._widget)
else:
self._topmost_widget = self._widget
pop_ups = property(lambda self:self._pop_ups, _set_pop_ups)
def set_alarm_in(self, sec, callback, user_data=None):
"""
Schedule an alarm in *sec* seconds that will call *callback* from the
within the :meth:`run` method.
:param sec: seconds until alarm
:type sec: float
:param callback: function to call with two parameters: this main loop
object and *user_data*
:type callback: callable
"""
def cb():
callback(self, user_data)
return self.event_loop.alarm(sec, cb)
def set_alarm_at(self, tm, callback, user_data=None):
"""
Schedule an alarm at *tm* time that will call *callback* from the
within the :meth:`run` function. Returns a handle that may be passed to
:meth:`remove_alarm`.
:param tm: time to call callback e.g. ``time.time() + 5``
:type tm: float
:param callback: function to call with two parameters: this main loop
object and *user_data*
:type callback: callable
"""
def cb():
callback(self, user_data)
return self.event_loop.alarm(tm - time.time(), cb)
def remove_alarm(self, handle):
"""
Remove an alarm. Return ``True`` if *handle* was found, ``False``
otherwise.
"""
return self.event_loop.remove_alarm(handle)
def watch_pipe(self, callback):
"""
Create a pipe for use by a subprocess or thread to trigger a callback
in the process/thread running the main loop.
:param callback: function taking one parameter to call from within
the process/thread running the main loop
:type callback: callable
This method returns a file descriptor attached to the write end of a
pipe. The read end of the pipe is added to the list of files
:attr:`event_loop` is watching. When data is written to the pipe the
callback function will be called and passed a single value containing
data read from the pipe.
This method may be used any time you want to update widgets from
another thread or subprocess.
Data may be written to the returned file descriptor with
``os.write(fd, data)``. Ensure that data is less than 512 bytes (or 4K
on Linux) so that the callback will be triggered just once with the
complete value of data passed in.
If the callback returns ``False`` then the watch will be removed from
:attr:`event_loop` and the read end of the pipe will be closed. You
are responsible for closing the write end of the pipe with
``os.close(fd)``.
"""
pipe_rd, pipe_wr = os.pipe()
fcntl.fcntl(pipe_rd, fcntl.F_SETFL, os.O_NONBLOCK)
watch_handle = None
def cb():
data = os.read(pipe_rd, PIPE_BUFFER_READ_SIZE)
rval = callback(data)
if rval is False:
self.event_loop.remove_watch_file(watch_handle)
os.close(pipe_rd)
watch_handle = self.event_loop.watch_file(pipe_rd, cb)
self._watch_pipes[pipe_wr] = (watch_handle, pipe_rd)
return pipe_wr
def remove_watch_pipe(self, write_fd):
"""
Close the read end of the pipe and remove the watch created by
:meth:`watch_pipe`. You are responsible for closing the write end of
the pipe.
Returns ``True`` if the watch pipe exists, ``False`` otherwise
"""
try:
watch_handle, pipe_rd = self._watch_pipes.pop(write_fd)
except KeyError:
return False
if not self.event_loop.remove_watch_file(watch_handle):
return False
os.close(pipe_rd)
return True
def watch_file(self, fd, callback):
"""
Call *callback* when *fd* has some data to read. No parameters are
passed to callback.
Returns a handle that may be passed to :meth:`remove_watch_file`.
"""
return self.event_loop.watch_file(fd, callback)
def remove_watch_file(self, handle):
"""
Remove a watch file. Returns ``True`` if the watch file
exists, ``False`` otherwise.
"""
return self.event_loop.remove_watch_file(handle)
def run(self):
"""
Start the main loop handling input events and updating the screen. The
loop will continue until an :exc:`ExitMainLoop` exception is raised.
If you would prefer to manage the event loop yourself, don't use this
method. Instead, call :meth:`start` before starting the event loop,
and :meth:`stop` once it's finished.
"""
try:
self._run()
except ExitMainLoop:
pass
def _test_run(self):
"""
>>> w = _refl("widget") # _refl prints out function calls
>>> w.render_rval = "fake canvas" # *_rval is used for return values
>>> scr = _refl("screen")
>>> scr.get_input_descriptors_rval = [42]
>>> scr.get_cols_rows_rval = (20, 10)
>>> scr.started = True
>>> scr._urwid_signals = {}
>>> evl = _refl("event_loop")
>>> evl.enter_idle_rval = 1
>>> evl.watch_file_rval = 2
>>> ml = MainLoop(w, [], scr, event_loop=evl)
>>> ml.run() # doctest:+ELLIPSIS
screen.start()
screen.set_mouse_tracking()
screen.unhook_event_loop(...)
screen.hook_event_loop(...)
event_loop.enter_idle(<bound method MainLoop.entering_idle...>)
event_loop.run()
event_loop.remove_enter_idle(1)
screen.unhook_event_loop(...)
screen.stop()
>>> ml.draw_screen() # doctest:+ELLIPSIS
screen.get_cols_rows()
widget.render((20, 10), focus=True)
screen.draw_screen((20, 10), 'fake canvas')
"""
def start(self):
"""
Sets up the main loop, hooking into the event loop where necessary.
Starts the :attr:`screen` if it hasn't already been started.
If you want to control starting and stopping the event loop yourself,
you should call this method before starting, and call `stop` once the
loop has finished. You may also use this method as a context manager,
which will stop the loop automatically at the end of the block:
with main_loop.start():
...
Note that some event loop implementations don't handle exceptions
specially if you manage the event loop yourself. In particular, the
Twisted and asyncio loops won't stop automatically when
:exc:`ExitMainLoop` (or anything else) is raised.
"""
self.screen.start()
if self.handle_mouse:
self.screen.set_mouse_tracking()
if not hasattr(self.screen, 'hook_event_loop'):
raise CantUseExternalLoop(
"Screen {0!r} doesn't support external event loops")
try:
signals.connect_signal(self.screen, INPUT_DESCRIPTORS_CHANGED,
self._reset_input_descriptors)
except NameError:
pass
# watch our input descriptors
self._reset_input_descriptors()
self.idle_handle = self.event_loop.enter_idle(self.entering_idle)
return StoppingContext(self)
def stop(self):
"""
Cleans up any hooks added to the event loop. Only call this if you're
managing the event loop yourself, after the loop stops.
"""
self.event_loop.remove_enter_idle(self.idle_handle)
del self.idle_handle
signals.disconnect_signal(self.screen, INPUT_DESCRIPTORS_CHANGED,
self._reset_input_descriptors)
self.screen.unhook_event_loop(self.event_loop)
self.screen.stop()
def _reset_input_descriptors(self):
self.screen.unhook_event_loop(self.event_loop)
self.screen.hook_event_loop(self.event_loop, self._update)
def _run(self):
try:
self.start()
except CantUseExternalLoop:
try:
return self._run_screen_event_loop()
finally:
self.screen.stop()
try:
self.event_loop.run()
except:
self.screen.stop() # clean up screen control
raise
self.stop()
def _update(self, keys, raw):
"""
>>> w = _refl("widget")
>>> w.selectable_rval = True
>>> w.mouse_event_rval = True
>>> scr = _refl("screen")
>>> scr.get_cols_rows_rval = (15, 5)
>>> evl = _refl("event_loop")
>>> ml = MainLoop(w, [], scr, event_loop=evl)
>>> ml._input_timeout = "old timeout"
>>> ml._update(['y'], [121]) # doctest:+ELLIPSIS
screen.get_cols_rows()
widget.selectable()
widget.keypress((15, 5), 'y')
>>> ml._update([("mouse press", 1, 5, 4)], [])
widget.mouse_event((15, 5), 'mouse press', 1, 5, 4, focus=True)
>>> ml._update([], [])
"""
keys = self.input_filter(keys, raw)
if keys:
self.process_input(keys)
if 'window resize' in keys:
self.screen_size = None
def _run_screen_event_loop(self):
"""
This method is used when the screen does not support using
external event loops.
The alarms stored in the SelectEventLoop in :attr:`event_loop`
are modified by this method.
"""
next_alarm = None
while True:
self.draw_screen()
if not next_alarm and self.event_loop._alarms:
next_alarm = heapq.heappop(self.event_loop._alarms)
keys = None
while not keys:
if next_alarm:
sec = max(0, next_alarm[0] - time.time())
self.screen.set_input_timeouts(sec)
else:
self.screen.set_input_timeouts(None)
keys, raw = self.screen.get_input(True)
if not keys and next_alarm:
sec = next_alarm[0] - time.time()
if sec <= 0:
break
keys = self.input_filter(keys, raw)
if keys:
self.process_input(keys)
while next_alarm:
sec = next_alarm[0] - time.time()
if sec > 0:
break
tm, tie_break, callback = next_alarm
callback()
if self.event_loop._alarms:
next_alarm = heapq.heappop(self.event_loop._alarms)
else:
next_alarm = None
if 'window resize' in keys:
self.screen_size = None
def _test_run_screen_event_loop(self):
"""
>>> w = _refl("widget")
>>> scr = _refl("screen")
>>> scr.get_cols_rows_rval = (10, 5)
>>> scr.get_input_rval = [], []
>>> ml = MainLoop(w, screen=scr)
>>> def stop_now(loop, data):
... raise ExitMainLoop()
>>> handle = ml.set_alarm_in(0, stop_now)
>>> try:
... ml._run_screen_event_loop()
... except ExitMainLoop:
... pass
screen.get_cols_rows()
widget.render((10, 5), focus=True)
screen.draw_screen((10, 5), None)
screen.set_input_timeouts(0)
screen.get_input(True)
"""
def process_input(self, keys):
"""
This method will pass keyboard input and mouse events to :attr:`widget`.
This method is called automatically from the :meth:`run` method when
there is input, but may also be called to simulate input from the user.
*keys* is a list of input returned from :attr:`screen`'s get_input()
or get_input_nonblocking() methods.
Returns ``True`` if any key was handled by a widget or the
:meth:`unhandled_input` method.
"""
if not self.screen_size:
self.screen_size = self.screen.get_cols_rows()
something_handled = False
for k in keys:
if k == 'window resize':
continue
if is_mouse_event(k):
event, button, col, row = k
if self._topmost_widget.mouse_event(self.screen_size,
event, button, col, row, focus=True ):
k = None
elif self._topmost_widget.selectable():
k = self._topmost_widget.keypress(self.screen_size, k)
if k:
if command_map[k] == REDRAW_SCREEN:
self.screen.clear()
something_handled = True
else:
something_handled |= bool(self.unhandled_input(k))
else:
something_handled = True
return something_handled
def _test_process_input(self):
"""
>>> w = _refl("widget")
>>> w.selectable_rval = True
>>> scr = _refl("screen")
>>> scr.get_cols_rows_rval = (10, 5)
>>> ml = MainLoop(w, [], scr)
>>> ml.process_input(['enter', ('mouse drag', 1, 14, 20)])
screen.get_cols_rows()
widget.selectable()
widget.keypress((10, 5), 'enter')
widget.mouse_event((10, 5), 'mouse drag', 1, 14, 20, focus=True)
True
"""
def input_filter(self, keys, raw):
"""
This function is passed each all the input events and raw keystroke
values. These values are passed to the *input_filter* function
passed to the constructor. That function must return a list of keys to
be passed to the widgets to handle. If no *input_filter* was
defined this implementation will return all the input events.
"""
if self._input_filter:
return self._input_filter(keys, raw)
return keys
def unhandled_input(self, input):
"""
This function is called with any input that was not handled by the
widgets, and calls the *unhandled_input* function passed to the
constructor. If no *unhandled_input* was defined then the input
will be ignored.
*input* is the keyboard or mouse input.
The *unhandled_input* function should return ``True`` if it handled
the input.
"""
if self._unhandled_input:
return self._unhandled_input(input)
def entering_idle(self):
"""
This method is called whenever the event loop is about to enter the
idle state. :meth:`draw_screen` is called here to update the
screen when anything has changed.
"""
if self.screen.started:
self.draw_screen()
def draw_screen(self):
"""
Render the widgets and paint the screen. This method is called
automatically from :meth:`entering_idle`.
If you modify the widgets displayed outside of handling input or
responding to an alarm you will need to call this method yourself
to repaint the screen.
"""
if not self.screen_size:
self.screen_size = self.screen.get_cols_rows()
canvas = self._topmost_widget.render(self.screen_size, focus=True)
self.screen.draw_screen(self.screen_size, canvas)
class EventLoop(object):
"""
Abstract class representing an event loop to be used by :class:`MainLoop`.
"""
def alarm(self, seconds, callback):
"""
Call callback() a given time from now. No parameters are
passed to callback.
This method has no default implementation.
Returns a handle that may be passed to remove_alarm()
seconds -- floating point time to wait before calling callback
callback -- function to call from event loop
"""
raise NotImplementedError()
def enter_idle(self, callback):
"""
Add a callback for entering idle.
This method has no default implementation.
Returns a handle that may be passed to remove_idle()
"""
raise NotImplementedError()
def remove_alarm(self, handle):
"""
Remove an alarm.
This method has no default implementation.
Returns True if the alarm exists, False otherwise
"""
raise NotImplementedError()
def remove_enter_idle(self, handle):
"""
Remove an idle callback.
This method has no default implementation.
Returns True if the handle was removed.
"""
raise NotImplementedError()
def remove_watch_file(self, handle):
"""
Remove an input file.
This method has no default implementation.
Returns True if the input file exists, False otherwise
"""
raise NotImplementedError()
def run(self):
"""
Start the event loop. Exit the loop when any callback raises
an exception. If ExitMainLoop is raised, exit cleanly.
This method has no default implementation.
"""
raise NotImplementedError()
def watch_file(self, fd, callback):
"""
Call callback() when fd has some data to read. No parameters
are passed to callback.
This method has no default implementation.
Returns a handle that may be passed to remove_watch_file()
fd -- file descriptor to watch for input
callback -- function to call when input is available
"""
raise NotImplementedError()
def set_signal_handler(self, signum, handler):
"""
Sets the signal handler for signal signum.
The default implementation of :meth:`set_signal_handler`
is simply a proxy function that calls :func:`signal.signal()`
and returns the resulting value.
signum -- signal number
handler -- function (taking signum as its single argument),
or `signal.SIG_IGN`, or `signal.SIG_DFL`
"""
return signal.signal(signum, handler)
class SelectEventLoop(EventLoop):
"""
Event loop based on :func:`select.select`
"""
def __init__(self):
self._alarms = []
self._watch_files = {}
self._idle_handle = 0
self._idle_callbacks = {}
self._tie_break = count()
def alarm(self, seconds, callback):
"""
Call callback() a given time from now. No parameters are
passed to callback.
Returns a handle that may be passed to remove_alarm()
seconds -- floating point time to wait before calling callback
callback -- function to call from event loop
"""
tm = time.time() + seconds
handle = (tm, next(self._tie_break), callback)
heapq.heappush(self._alarms, handle)
return handle
def remove_alarm(self, handle):
"""
Remove an alarm.
Returns True if the alarm exists, False otherwise
"""
try:
self._alarms.remove(handle)
heapq.heapify(self._alarms)
return True
except ValueError:
return False
def watch_file(self, fd, callback):
"""
Call callback() when fd has some data to read. No parameters
are passed to callback.
Returns a handle that may be passed to remove_watch_file()
fd -- file descriptor to watch for input
callback -- function to call when input is available
"""
self._watch_files[fd] = callback
return fd
def remove_watch_file(self, handle):
"""
Remove an input file.
Returns True if the input file exists, False otherwise
"""
if handle in self._watch_files:
del self._watch_files[handle]
return True
return False
def enter_idle(self, callback):
"""
Add a callback for entering idle.
Returns a handle that may be passed to remove_idle()
"""
self._idle_handle += 1
self._idle_callbacks[self._idle_handle] = callback
return self._idle_handle
def remove_enter_idle(self, handle):
"""
Remove an idle callback.
Returns True if the handle was removed.
"""
try:
del self._idle_callbacks[handle]
except KeyError:
return False
return True
def _entering_idle(self):
"""
Call all the registered idle callbacks.
"""
for callback in self._idle_callbacks.values():
callback()
def run(self):
"""
Start the event loop. Exit the loop when any callback raises
an exception. If ExitMainLoop is raised, exit cleanly.
"""
try:
self._did_something = True
while True:
try:
self._loop()
except select.error as e:
if e.args[0] != 4:
# not just something we need to retry
raise
except ExitMainLoop:
pass
def _loop(self):
"""
A single iteration of the event loop
"""
fds = list(self._watch_files.keys())
if self._alarms or self._did_something:
if self._alarms:
tm = self._alarms[0][0]
timeout = max(0, tm - time.time())
if self._did_something and (not self._alarms or
(self._alarms and timeout > 0)):
timeout = 0
tm = 'idle'
ready, w, err = select.select(fds, [], fds, timeout)
else:
tm = None
ready, w, err = select.select(fds, [], fds)
if not ready:
if tm == 'idle':
self._entering_idle()
self._did_something = False
elif tm is not None:
# must have been a timeout
tm, tie_break, alarm_callback = heapq.heappop(self._alarms)
alarm_callback()
self._did_something = True
for fd in ready:
self._watch_files[fd]()
self._did_something = True
class GLibEventLoop(EventLoop):
"""
Event loop based on GLib.MainLoop
"""
def __init__(self):
from gi.repository import GLib
self.GLib = GLib
self._alarms = []
self._watch_files = {}
self._idle_handle = 0
self._glib_idle_enabled = False # have we called glib.idle_add?
self._idle_callbacks = {}
self._loop = GLib.MainLoop()
self._exc_info = None
self._enable_glib_idle()
self._signal_handlers = {}
def alarm(self, seconds, callback):
"""
Call callback() a given time from now. No parameters are
passed to callback.
Returns a handle that may be passed to remove_alarm()
seconds -- floating point time to wait before calling callback
callback -- function to call from event loop
"""
@self.handle_exit
def ret_false():
callback()
self._enable_glib_idle()
return False
fd = self.GLib.timeout_add(int(seconds*1000), ret_false)
self._alarms.append(fd)
return (fd, callback)
def set_signal_handler(self, signum, handler):
"""
Sets the signal handler for signal signum.
.. WARNING::
Because this method uses the `GLib`-specific `unix_signal_add`
function, its behaviour is different than `signal.signal().`
If `signum` is not `SIGHUP`, `SIGINT`, `SIGTERM`, `SIGUSR1`,
`SIGUSR2` or `SIGWINCH`, this method performs no actions and
immediately returns None.
Returns None in all cases (unlike :func:`signal.signal()`).
..
signum -- signal number
handler -- function (taking signum as its single argument),
or `signal.SIG_IGN`, or `signal.SIG_DFL`
"""
glib_signals = [
signal.SIGHUP,
signal.SIGINT,
signal.SIGTERM,
signal.SIGUSR1,
signal.SIGUSR2,
signal.SIGWINCH
]
if signum not in glib_signals:
# The GLib event loop supports only the signals listed above
return
if signum in self._signal_handlers:
self.GLib.source_remove(self._signal_handlers.pop(signum))
if handler == signal.SIG_IGN:
handler = lambda x: None
elif handler == signal.SIG_DFL:
return
def final_handler(signal_number):
handler(signal_number)
return self.GLib.SOURCE_CONTINUE
source = self.GLib.unix_signal_add(self.GLib.PRIORITY_DEFAULT, signum, final_handler, signum)
self._signal_handlers[signum] = source
def remove_alarm(self, handle):
"""
Remove an alarm.
Returns True if the alarm exists, False otherwise
"""
try:
self._alarms.remove(handle[0])
self.GLib.source_remove(handle[0])
return True
except ValueError:
return False
def watch_file(self, fd, callback):
"""
Call callback() when fd has some data to read. No parameters
are passed to callback.
Returns a handle that may be passed to remove_watch_file()
fd -- file descriptor to watch for input
callback -- function to call when input is available
"""
@self.handle_exit
def io_callback(source, cb_condition):
callback()
self._enable_glib_idle()
return True
self._watch_files[fd] = \
self.GLib.io_add_watch(fd,self.GLib.IO_IN,io_callback)
return fd
def remove_watch_file(self, handle):
"""
Remove an input file.
Returns True if the input file exists, False otherwise
"""
if handle in self._watch_files:
self.GLib.source_remove(self._watch_files[handle])
del self._watch_files[handle]
return True
return False
def enter_idle(self, callback):
"""
Add a callback for entering idle.
Returns a handle that may be passed to remove_enter_idle()
"""
self._idle_handle += 1
self._idle_callbacks[self._idle_handle] = callback
return self._idle_handle
def _enable_glib_idle(self):
if self._glib_idle_enabled:
return
self.GLib.idle_add(self._glib_idle_callback)
self._glib_idle_enabled = True
def _glib_idle_callback(self):
for callback in self._idle_callbacks.values():
callback()
self._glib_idle_enabled = False
return False # ask glib not to call again (or we would be called
def remove_enter_idle(self, handle):
"""
Remove an idle callback.
Returns True if the handle was removed.
"""
try:
del self._idle_callbacks[handle]
except KeyError:
return False
return True
def run(self):
"""
Start the event loop. Exit the loop when any callback raises
an exception. If ExitMainLoop is raised, exit cleanly.
"""
try:
self._loop.run()
finally:
if self._loop.is_running():
self._loop.quit()
if self._exc_info:
# An exception caused us to exit, raise it now
exc_info = self._exc_info
self._exc_info = None
reraise(*exc_info)
def handle_exit(self,f):
"""
Decorator that cleanly exits the :class:`GLibEventLoop` if
:exc:`ExitMainLoop` is thrown inside of the wrapped function. Store the
exception info if some other exception occurs, it will be reraised after
the loop quits.
*f* -- function to be wrapped
"""
def wrapper(*args,**kargs):
try:
return f(*args,**kargs)
except ExitMainLoop:
self._loop.quit()
except:
import sys
self._exc_info = sys.exc_info()
if self._loop.is_running():
self._loop.quit()
return False
return wrapper
class TornadoEventLoop(EventLoop):
""" This is an Urwid-specific event loop to plug into its MainLoop.
It acts as an adaptor for Tornado's IOLoop which does all
heavy lifting except idle-callbacks.
Notice, since Tornado has no concept of idle callbacks we
monkey patch ioloop._impl.poll() function to be able to detect
potential idle periods.
"""
_ioloop_registry = WeakKeyDictionary() # {<ioloop> : {<handle> : <idle_func>}}
_max_idle_handle = 0
class PollProxy(object):
""" A simple proxy for a Python's poll object that wraps the .poll() method
in order to detect idle periods and call Urwid callbacks
"""
def __init__(self, poll_obj, idle_map):
self.__poll_obj = poll_obj
self.__idle_map = idle_map
self._idle_done = False
self._prev_timeout = 0
def __getattr__(self, name):
return getattr(self.__poll_obj, name)
def poll(self, timeout):
if timeout > self._prev_timeout:
# if timeout increased we assume a timer event was handled
self._idle_done = False
self._prev_timeout = timeout
start = time.time()
# any IO pending wins
events = self.__poll_obj.poll(0)
if events:
self._idle_done = False
return events
# our chance to enter idle
if not self._idle_done:
for callback in self.__idle_map.values():
callback()
self._idle_done = True
# then complete the actual request (adjusting timeout)
timeout = max(0, min(timeout, timeout + start - time.time()))
events = self.__poll_obj.poll(timeout)
if events:
self._idle_done = False
return events
@classmethod
def _patch_poll_impl(cls, ioloop):
""" Wraps original poll object in the IOLoop's poll object
"""
if ioloop in cls._ioloop_registry:
return # we already patched this instance
cls._ioloop_registry[ioloop] = idle_map = {}
ioloop._impl = cls.PollProxy(ioloop._impl, idle_map)
def __init__(self, ioloop=None):
if not ioloop:
from tornado.ioloop import IOLoop
ioloop = IOLoop.instance()
self._ioloop = ioloop
self._patch_poll_impl(ioloop)
self._pending_alarms = {}
self._watch_handles = {} # {<watch_handle> : <file_descriptor>}
self._max_watch_handle = 0
self._exception = None
def alarm(self, secs, callback):
ioloop = self._ioloop
def wrapped():
try:
del self._pending_alarms[handle]
except KeyError:
pass
self.handle_exit(callback)()
handle = ioloop.add_timeout(ioloop.time() + secs, wrapped)
self._pending_alarms[handle] = 1
return handle
def remove_alarm(self, handle):
self._ioloop.remove_timeout(handle)
try:
del self._pending_alarms[handle]
except KeyError:
return False
else:
return True
def watch_file(self, fd, callback):
from tornado.ioloop import IOLoop
handler = lambda fd,events: self.handle_exit(callback)()
self._ioloop.add_handler(fd, handler, IOLoop.READ)
self._max_watch_handle += 1
handle = self._max_watch_handle
self._watch_handles[handle] = fd
return handle
def remove_watch_file(self, handle):
fd = self._watch_handles.pop(handle, None)
if fd is None:
return False
else:
self._ioloop.remove_handler(fd)
return True
def enter_idle(self, callback):
self._max_idle_handle += 1
handle = self._max_idle_handle
idle_map = self._ioloop_registry[self._ioloop]
idle_map[handle] = callback
return handle
def remove_enter_idle(self, handle):
idle_map = self._ioloop_registry[self._ioloop]
cb = idle_map.pop(handle, None)
return cb is not None
def handle_exit(self, func):
@wraps(func)
def wrapper(*args, **kw):
try:
return func(*args, **kw)
except ExitMainLoop:
self._ioloop.stop()
except Exception as exc:
self._exception = exc
self._ioloop.stop()
return False
return wrapper
def run(self):
self._ioloop.start()
if self._exception:
exc, self._exception = self._exception, None
raise exc
try:
from twisted.internet.abstract import FileDescriptor
except ImportError:
FileDescriptor = object
class TwistedInputDescriptor(FileDescriptor):
def __init__(self, reactor, fd, cb):
self._fileno = fd
self.cb = cb
FileDescriptor.__init__(self, reactor)
def fileno(self):
return self._fileno
def doRead(self):
return self.cb()
class TwistedEventLoop(EventLoop):
"""
Event loop based on Twisted_
"""
_idle_emulation_delay = 1.0/256 # a short time (in seconds)
def __init__(self, reactor=None, manage_reactor=True):
"""
:param reactor: reactor to use
:type reactor: :class:`twisted.internet.reactor`.
:param: manage_reactor: `True` if you want this event loop to run
and stop the reactor.
:type manage_reactor: boolean
.. WARNING::
Twisted's reactor doesn't like to be stopped and run again. If you
need to stop and run your :class:`MainLoop`, consider setting
``manage_reactor=False`` and take care of running/stopping the reactor
at the beginning/ending of your program yourself.
You can also forego using :class:`MainLoop`'s run() entirely, and
instead call start() and stop() before and after starting the
reactor.
.. _Twisted: http://twistedmatrix.com/trac/
"""
if reactor is None:
import twisted.internet.reactor
reactor = twisted.internet.reactor
self.reactor = reactor
self._alarms = []
self._watch_files = {}
self._idle_handle = 0
self._twisted_idle_enabled = False
self._idle_callbacks = {}
self._exc_info = None
self.manage_reactor = manage_reactor
self._enable_twisted_idle()
def alarm(self, seconds, callback):
"""
Call callback() a given time from now. No parameters are
passed to callback.
Returns a handle that may be passed to remove_alarm()
seconds -- floating point time to wait before calling callback
callback -- function to call from event loop
"""
handle = self.reactor.callLater(seconds, self.handle_exit(callback))
return handle
def remove_alarm(self, handle):
"""
Remove an alarm.
Returns True if the alarm exists, False otherwise
"""
from twisted.internet.error import AlreadyCancelled, AlreadyCalled
try:
handle.cancel()
return True
except AlreadyCancelled:
return False
except AlreadyCalled:
return False
def watch_file(self, fd, callback):
"""
Call callback() when fd has some data to read. No parameters
are passed to callback.
Returns a handle that may be passed to remove_watch_file()
fd -- file descriptor to watch for input
callback -- function to call when input is available
"""
ind = TwistedInputDescriptor(self.reactor, fd,
self.handle_exit(callback))
self._watch_files[fd] = ind
self.reactor.addReader(ind)
return fd
def remove_watch_file(self, handle):
"""
Remove an input file.
Returns True if the input file exists, False otherwise
"""
if handle in self._watch_files:
self.reactor.removeReader(self._watch_files[handle])
del self._watch_files[handle]
return True
return False
def enter_idle(self, callback):
"""
Add a callback for entering idle.
Returns a handle that may be passed to remove_enter_idle()
"""
self._idle_handle += 1
self._idle_callbacks[self._idle_handle] = callback
return self._idle_handle
def _enable_twisted_idle(self):
"""
Twisted's reactors don't have an idle or enter-idle callback
so the best we can do for now is to set a timer event in a very
short time to approximate an enter-idle callback.
.. WARNING::
This will perform worse than the other event loops until we can find a
fix or workaround
"""
if self._twisted_idle_enabled:
return
self.reactor.callLater(self._idle_emulation_delay,
self.handle_exit(self._twisted_idle_callback, enable_idle=False))
self._twisted_idle_enabled = True
def _twisted_idle_callback(self):
for callback in self._idle_callbacks.values():
callback()
self._twisted_idle_enabled = False
def remove_enter_idle(self, handle):
"""
Remove an idle callback.
Returns True if the handle was removed.
"""
try:
del self._idle_callbacks[handle]
except KeyError:
return False
return True
def run(self):
"""
Start the event loop. Exit the loop when any callback raises
an exception. If ExitMainLoop is raised, exit cleanly.
"""
if not self.manage_reactor:
return
self.reactor.run()
if self._exc_info:
# An exception caused us to exit, raise it now
exc_info = self._exc_info
self._exc_info = None
reraise(*exc_info)
def handle_exit(self, f, enable_idle=True):
"""
Decorator that cleanly exits the :class:`TwistedEventLoop` if
:class:`ExitMainLoop` is thrown inside of the wrapped function. Store the
exception info if some other exception occurs, it will be reraised after
the loop quits.
*f* -- function to be wrapped
"""
def wrapper(*args,**kargs):
rval = None
try:
rval = f(*args,**kargs)
except ExitMainLoop:
if self.manage_reactor:
self.reactor.stop()
except:
import sys
print(sys.exc_info())
self._exc_info = sys.exc_info()
if self.manage_reactor:
self.reactor.crash()
if enable_idle:
self._enable_twisted_idle()
return rval
return wrapper
class AsyncioEventLoop(EventLoop):
"""
Event loop based on the standard library ``asyncio`` module.
``asyncio`` is new in Python 3.4, but also exists as a backport on PyPI for
Python 3.3. The ``trollius`` package is available for older Pythons with
slightly different syntax, but also works with this loop.
"""
_we_started_event_loop = False
_idle_emulation_delay = 1.0/256 # a short time (in seconds)
def __init__(self, **kwargs):
if 'loop' in kwargs:
self._loop = kwargs.pop('loop')
else:
import asyncio
self._loop = asyncio.get_event_loop()
def alarm(self, seconds, callback):
"""
Call callback() a given time from now. No parameters are
passed to callback.
Returns a handle that may be passed to remove_alarm()
seconds -- time in seconds to wait before calling callback
callback -- function to call from event loop
"""
return self._loop.call_later(seconds, callback)
def remove_alarm(self, handle):
"""
Remove an alarm.
Returns True if the alarm exists, False otherwise
"""
existed = not handle._cancelled
handle.cancel()
return existed
def watch_file(self, fd, callback):
"""
Call callback() when fd has some data to read. No parameters
are passed to callback.
Returns a handle that may be passed to remove_watch_file()
fd -- file descriptor to watch for input
callback -- function to call when input is available
"""
self._loop.add_reader(fd, callback)
return fd
def remove_watch_file(self, handle):
"""
Remove an input file.
Returns True if the input file exists, False otherwise
"""
return self._loop.remove_reader(handle)
def enter_idle(self, callback):
"""
Add a callback for entering idle.
Returns a handle that may be passed to remove_idle()
"""
# XXX there's no such thing as "idle" in most event loops; this fakes
# it the same way as Twisted, by scheduling the callback to be called
# repeatedly
mutable_handle = [None]
def faux_idle_callback():
callback()
mutable_handle[0] = self._loop.call_later(
self._idle_emulation_delay, faux_idle_callback)
mutable_handle[0] = self._loop.call_later(
self._idle_emulation_delay, faux_idle_callback)
return mutable_handle
def remove_enter_idle(self, handle):
"""
Remove an idle callback.
Returns True if the handle was removed.
"""
# `handle` is just a list containing the current actual handle
return self.remove_alarm(handle[0])
_exc_info = None
def _exception_handler(self, loop, context):
exc = context.get('exception')
if exc:
loop.stop()
if not isinstance(exc, ExitMainLoop):
# Store the exc_info so we can re-raise after the loop stops
import sys
self._exc_info = sys.exc_info()
else:
loop.default_exception_handler(context)
def run(self):
"""
Start the event loop. Exit the loop when any callback raises
an exception. If ExitMainLoop is raised, exit cleanly.
"""
self._loop.set_exception_handler(self._exception_handler)
self._loop.run_forever()
if self._exc_info:
exc_info = self._exc_info
self._exc_info = None
reraise(*exc_info)
def _refl(name, rval=None, exit=False):
"""
This function is used to test the main loop classes.
>>> scr = _refl("screen")
>>> scr.function("argument")
screen.function('argument')
>>> scr.callme(when="now")
screen.callme(when='now')
>>> scr.want_something_rval = 42
>>> x = scr.want_something()
screen.want_something()
>>> x
42
"""
class Reflect(object):
def __init__(self, name, rval=None):
self._name = name
self._rval = rval
def __call__(self, *argl, **argd):
args = ", ".join([repr(a) for a in argl])
if args and argd:
args = args + ", "
args = args + ", ".join([k+"="+repr(v) for k,v in argd.items()])
print(self._name+"("+args+")")
if exit:
raise ExitMainLoop()
return self._rval
def __getattr__(self, attr):
if attr.endswith("_rval"):
raise AttributeError()
#print self._name+"."+attr
if hasattr(self, attr+"_rval"):
return Reflect(self._name+"."+attr, getattr(self, attr+"_rval"))
return Reflect(self._name+"."+attr)
return Reflect(name)
def _test():
import doctest
doctest.testmod()
if __name__=='__main__':
_test()
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