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#!/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(seconds1000), 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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