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
|
__all__ = ('Runner', 'run')
import contextvars
import enum
import functools
import threading
import signal
import sys
from . import coroutines
from . import events
from . import exceptions
from . import tasks
class _State(enum.Enum):
CREATED = "created"
INITIALIZED = "initialized"
CLOSED = "closed"
class Runner:
"""A context manager that controls event loop life cycle.
The context manager always creates a new event loop,
allows to run async functions inside it,
and properly finalizes the loop at the context manager exit.
If debug is True, the event loop will be run in debug mode.
If loop_factory is passed, it is used for new event loop creation.
asyncio.run(main(), debug=True)
is a shortcut for
with asyncio.Runner(debug=True) as runner:
runner.run(main())
The run() method can be called multiple times within the runner's context.
This can be useful for interactive console (e.g. IPython),
unittest runners, console tools, -- everywhere when async code
is called from existing sync framework and where the preferred single
asyncio.run() call doesn't work.
"""
# Note: the class is final, it is not intended for inheritance.
def __init__(self, *, debug=None, loop_factory=None):
self._state = _State.CREATED
self._debug = debug
self._loop_factory = loop_factory
self._loop = None
self._context = None
self._interrupt_count = 0
self._set_event_loop = False
def __enter__(self):
self._lazy_init()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.close()
def close(self):
"""Shutdown and close event loop."""
if self._state is not _State.INITIALIZED:
return
try:
loop = self._loop
_cancel_all_tasks(loop)
loop.run_until_complete(loop.shutdown_asyncgens())
loop.run_until_complete(loop.shutdown_default_executor())
finally:
if self._set_event_loop:
events.set_event_loop(None)
loop.close()
self._loop = None
self._state = _State.CLOSED
def get_loop(self):
"""Return embedded event loop."""
self._lazy_init()
return self._loop
def run(self, coro, *, context=None):
"""Run a coroutine inside the embedded event loop."""
if not coroutines.iscoroutine(coro):
raise ValueError("a coroutine was expected, got {!r}".format(coro))
if events._get_running_loop() is not None:
# fail fast with short traceback
raise RuntimeError(
"Runner.run() cannot be called from a running event loop")
self._lazy_init()
if context is None:
context = self._context
task = self._loop.create_task(coro, context=context)
if (threading.current_thread() is threading.main_thread()
and signal.getsignal(signal.SIGINT) is signal.default_int_handler
):
sigint_handler = functools.partial(self._on_sigint, main_task=task)
try:
signal.signal(signal.SIGINT, sigint_handler)
except ValueError:
# `signal.signal` may throw if `threading.main_thread` does
# not support signals (e.g. embedded interpreter with signals
# not registered - see gh-91880)
sigint_handler = None
else:
sigint_handler = None
self._interrupt_count = 0
try:
return self._loop.run_until_complete(task)
except exceptions.CancelledError:
if self._interrupt_count > 0:
uncancel = getattr(task, "uncancel", None)
if uncancel is not None and uncancel() == 0:
raise KeyboardInterrupt()
raise # CancelledError
finally:
if (sigint_handler is not None
and signal.getsignal(signal.SIGINT) is sigint_handler
):
signal.signal(signal.SIGINT, signal.default_int_handler)
def _lazy_init(self):
if self._state is _State.CLOSED:
raise RuntimeError("Runner is closed")
if self._state is _State.INITIALIZED:
return
if self._loop_factory is None:
self._loop = events.new_event_loop()
if not self._set_event_loop:
# Call set_event_loop only once to avoid calling
# attach_loop multiple times on child watchers
events.set_event_loop(self._loop)
self._set_event_loop = True
else:
self._loop = self._loop_factory()
if self._debug is not None:
self._loop.set_debug(self._debug)
self._context = contextvars.copy_context()
self._state = _State.INITIALIZED
def _on_sigint(self, signum, frame, main_task):
self._interrupt_count += 1
if self._interrupt_count == 1 and not main_task.done():
main_task.cancel()
# wakeup loop if it is blocked by select() with long timeout
self._loop.call_soon_threadsafe(lambda: None)
return
raise KeyboardInterrupt()
def run(main, *, debug=None):
"""Execute the coroutine and return the result.
This function runs the passed coroutine, taking care of
managing the asyncio event loop and finalizing asynchronous
generators.
This function cannot be called when another asyncio event loop is
running in the same thread.
If debug is True, the event loop will be run in debug mode.
This function always creates a new event loop and closes it at the end.
It should be used as a main entry point for asyncio programs, and should
ideally only be called once.
Example:
async def main():
await asyncio.sleep(1)
print('hello')
asyncio.run(main())
"""
if events._get_running_loop() is not None:
# fail fast with short traceback
raise RuntimeError(
"asyncio.run() cannot be called from a running event loop")
with Runner(debug=debug) as runner:
return runner.run(main)
def _cancel_all_tasks(loop):
to_cancel = tasks.all_tasks(loop)
if not to_cancel:
return
for task in to_cancel:
task.cancel()
loop.run_until_complete(tasks.gather(*to_cancel, return_exceptions=True))
for task in to_cancel:
if task.cancelled():
continue
if task.exception() is not None:
loop.call_exception_handler({
'message': 'unhandled exception during asyncio.run() shutdown',
'exception': task.exception(),
'task': task,
})
|
