1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
|
# (C) Copyright 2005-2023 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!
"""
Interfaces and base classes for cross-toolkit timers
This module defines interfaces for toolkit event-loop based timers. It also
provides a base implementation that can be easily specialized for a particular
back-end, and mixins that provide additional capabilities.
"""
from abc import abstractmethod
import time
from traits.api import (
ABCHasTraits,
Bool,
Callable,
Dict,
Event,
Float,
HasTraits,
Int,
Interface,
Property,
Range,
Tuple,
provides,
Union,
)
perf_counter = time.perf_counter
class ITimer(Interface):
""" Interface for timer classes.
This is a base interface which doesn't specify any particular notification
mechanism.
"""
# ITimer interface -------------------------------------------------------
#: The interval at which to call the callback in seconds.
interval = Range(low=0.0)
#: The number of times to repeat the callback, or None if no limit.
repeat = Union(None, Int)
#: The maximum length of time to run in seconds, or None if no limit.
expire = Union(None, Float)
#: Whether or not the timer is currently running.
active = Bool()
# -------------------------------------------------------------------------
# ITimer interface
# -------------------------------------------------------------------------
@classmethod
def timer(cls, **traits):
""" Convenience method that creates and starts a timer.
"""
pass
@classmethod
def single_shot(cls, **traits):
""" Convenience method that creates and starts a single-shot timer.
"""
pass
def start(self):
""" Start the timer. """
pass
def stop(self):
""" Stop the timer. """
pass
def perform(self):
""" The method that will be called by the timer. """
pass
class IEventTimer(ITimer):
""" Interface for timers which fire a trait event periodically. """
# IEventTimer interface --------------------------------------------------
#: A traits Event to fire when the callback happens.
timeout = Event()
class ICallbackTimer(ITimer):
""" Interface for timers which call a callback periodically. """
# ICallbackTimer interface -----------------------------------------------
#: The callback to make, or None if no callback.
callback = Callable
#: Positional arguments to give the callback.
args = Tuple()
#: Keyword arguments to give the callback.
kwargs = Dict()
@provides(ITimer)
class BaseTimer(ABCHasTraits):
""" Base class for timer classes.
This class has a class variable which tracks active timers to prevent
failures caused by garbage collection. A timer is added to this tracker
when it is started if the repeat value is not None.
"""
# BaseTimer interface ----------------------------------------------------
#: Class variable tracking all active timers.
_active_timers = set()
# ITimer interface -------------------------------------------------------
#: The interval at which to call the callback in seconds.
interval = Range(low=0.0, value=0.05)
#: The number of times to repeat the callback, or None if no limit.
repeat = Union(None, Int)
#: The maximum length of time to run in seconds, or None if no limit.
expire = Union(None, Float)
#: Property that controls the state of the timer.
active = Property(Bool, observe="_active")
# Private interface ------------------------------------------------------
#: Whether or not the timer is currently running.
_active = Bool()
#: The most recent start time.
_start_time = Float()
# -------------------------------------------------------------------------
# ITimer interface
# -------------------------------------------------------------------------
@classmethod
def timer(cls, **traits):
""" Convenience method that creates and starts a timer.
"""
timer = cls(**traits)
timer.start()
return timer
@classmethod
def single_shot(cls, **traits):
timer = cls(repeat=1, **traits)
timer.start()
return timer
def start(self):
""" Start the timer. """
if not self._active:
if self.repeat is not None:
self._active_timers.add(self)
if self.expire is not None:
self._start_time = perf_counter()
self._active = True
self._start()
def stop(self):
""" Stop the timer. """
if self._active:
self._active_timers.discard(self)
self._stop()
self._active = False
def perform(self):
""" Perform the callback.
The timer will stop if repeats is not None and less than 1, or if
the `_perform` method raises StopIteration.
"""
if self.expire is not None:
if perf_counter() - self._start_time > self.expire:
self.stop()
return
if self.repeat is not None:
self.repeat -= 1
try:
self._perform()
except StopIteration:
self.stop()
except:
self.stop()
raise
else:
if self.repeat is not None and self.repeat <= 0:
self.stop()
self.repeat = 0
# BaseTimer Protected methods
def _start(self):
""" Start the toolkit timer.
Subclasses should overrided this method.
"""
raise NotImplementedError()
def _stop(self):
""" Stop the toolkit timer.
Subclasses should overrided this method.
"""
raise NotImplementedError()
@abstractmethod
def _perform(self):
""" perform the appropriate action.
Subclasses should overrided this method.
"""
raise NotImplementedError()
# -------------------------------------------------------------------------
# Private interface
# -------------------------------------------------------------------------
# Trait property handlers ------------------------------------------------
def _get_active(self):
return self._active
def _set_active(self, value):
if value:
self.start()
else:
self.stop()
@provides(IEventTimer)
class MEventTimer(HasTraits):
""" Mixin for event timer classes.
Other code can listen to the `timeout` event using standard traits
listeners.
"""
# IEventTimer interface --------------------------------------------------
#: A traits Event to fire when the callback happens.
timeout = Event()
# -------------------------------------------------------------------------
# ITimer interface
# -------------------------------------------------------------------------
# ITimer Protected methods -----------------------------------------------
def _perform(self):
""" Fire the event. """
self.timeout = True
@provides(ITimer)
class MCallbackTimer(HasTraits):
""" Mixin for callback timer classes.
"""
# ICallbackTimer interface -----------------------------------------------
#: The callback to make.
callback = Callable
#: Positional arguments to give the callback.
args = Tuple()
#: Keyword arguments to give the callback.
kwargs = Dict()
# -------------------------------------------------------------------------
# ITimer interface
# -------------------------------------------------------------------------
# ITimer Protected methods -----------------------------------------------
def _perform(self):
""" Perform the callback. """
self.callback(*self.args, **self.kwargs)
|
