import asyncio
import logging
import threading
from contextlib import contextmanager
from functools import partial
from .base import Session
from ..exceptions import SessionNotFoundException, SessionClosedException, SessionException
from ..utils import random_str, isgeneratorfunction, iscoroutinefunction
logger = logging.getLogger(__name__)
class WebIOFuture:
def __init__(self, coro=None):
self.coro = coro
def __iter__(self):
result = yield self
return result
__await__ = __iter__ # make compatible with 'await' expression
class _context:
current_session = None # type:"CoroutineBasedSession"
current_task_id = None
class CoroutineBasedSession(Session):
"""
基于协程的任务会话
当主协程任务和会话内所有通过 `run_async` 注册的协程都退出后，会话关闭。
当用户浏览器主动关闭会话，CoroutineBasedSession.close 被调用， 协程任务和会话内所有通过 `run_async` 注册的协程都被关闭。
"""
# 运行事件循环的线程id
# 用于在 CoroutineBasedSession.get_current_session() 判断调用方是否合法
# Tornado backend时，在创建第一个CoroutineBasedSession时初始化
# Flask backend时，在platform.flaskrun_event_loop()时初始化
event_loop_thread_id = None
@classmethod
def get_current_session(cls) -> "CoroutineBasedSession":
if _context.current_session is None or cls.event_loop_thread_id != threading.current_thread().ident:
raise SessionNotFoundException("No session found in current context!")
if _context.current_session.closed():
raise SessionClosedException
return _context.current_session
@staticmethod
def get_current_task_id():
if _context.current_task_id is None:
raise RuntimeError("No current task found in context!")
return _context.current_task_id
def __init__(self, target, session_info, on_task_command=None, on_session_close=None):
"""
:param target: 协程函数
:param on_task_command: 由协程内发给session的消息的处理函数
:param on_session_close: 会话结束的处理函数。后端Backend在相应on_session_close时关闭连接时，需要保证会话内的所有消息都传送到了客户端
"""
assert iscoroutinefunction(target) or isgeneratorfunction(target), ValueError(
"CoroutineBasedSession accept coroutine function or generator function as task function")
super().__init__(session_info)
cls = type(self)
self._on_task_command = on_task_command or (lambda _: None)
self._on_session_close = on_session_close or (lambda: None)
# 当前会话未被Backend处理的消息
self.unhandled_task_msgs = []
# 在创建第一个CoroutineBasedSession时 event_loop_thread_id 还未被初始化
# 则当前线程即为运行 event loop 的线程
if cls.event_loop_thread_id is None:
cls.event_loop_thread_id = threading.current_thread().ident
# 会话内的协程任务
self.coros = {} # coro_task_id -> Task()
self._closed = False
self._need_keep_alive = False
# 当前会话未结束运行(已创建和正在运行的)的协程数量。当 _alive_coro_cnt 变为 0 时，会话结束。
self._alive_coro_cnt = 1
main_task = Task(self._start_main_task(target), session=self, on_coro_stop=self._on_task_finish)
self.coros[main_task.coro_id] = main_task
self._step_task(main_task)
async def _start_main_task(self, target):
await target()
if self.need_keep_alive():
from ..session import hold
await hold()
def _step_task(self, task, result=None):
asyncio.get_event_loop().call_soon_threadsafe(partial(task.step, result))
def _on_task_finish(self, task: "Task"):
self._alive_coro_cnt -= 1
if task.coro_id in self.coros:
logger.debug('del self.coros[%s]', task.coro_id)
del self.coros[task.coro_id]
if self._alive_coro_cnt <= 0 and not self.closed():
self.send_task_command(dict(command='close_session'))
self._on_session_close()
self.close()
def send_task_command(self, command):
"""向会话发送来自协程内的消息
:param dict command: 消息
"""
if self.closed():
raise SessionClosedException()
self.unhandled_task_msgs.append(command)
self._on_task_command(self)
async def next_client_event(self):
# 函数开始不需要判断 self.closed()
# 如果会话关闭，对 get_current_session().next_client_event() 的调用会抛出SessionClosedException
return await WebIOFuture()
def send_client_event(self, event):
"""向会话发送来自用户浏览器的事件️
:param dict event: 事件️消息
"""
coro_id = event['task_id']
coro = self.coros.get(coro_id)
if not coro:
logger.error('coro not found, coro_id:%s', coro_id)
return
self._step_task(coro, event)
def get_task_commands(self):
msgs = self.unhandled_task_msgs
self.unhandled_task_msgs = []
return msgs
def _cleanup(self):
for t in list(self.coros.values()): # t.close() may cause self.coros changed size
t.step(SessionClosedException, throw_exp=True)
# in case that the task catch the SessionClosedException, we need to close it manually
t.close()
self.coros = {} # delete session tasks
# reset the reference, to avoid circular reference
self._on_session_close = None
self._on_task_command = None
def close(self, nonblock=False):
"""关闭当前Session。由Backend调用"""
if self.closed():
return
super().close()
self._cleanup()
def register_callback(self, callback, mutex_mode=False):
""" 向Session注册一个回调函数，返回回调id
:type callback: Callable or Coroutine
:param callback: 回调函数. 函数签名为 ``callback(data)``. ``data`` 参数为回调事件的值
:param bool mutex_mode: 互斥模式。若为 ``True`` ，则在运行回调函数过程中，无法响应同一组件（callback_id相同）的新点击事件，仅当 ``callback`` 为协程函数时有效
:return str: 回调id.
"""
async def callback_coro():
while True:
try:
event = await self.next_client_event()
except SessionClosedException:
return
assert event['event'] == 'callback'
coro = None
if iscoroutinefunction(callback):
coro = callback(event['data'])
elif isgeneratorfunction(callback):
coro = asyncio.coroutine(callback)(event['data'])
else:
try:
res = callback(event['data'])
if asyncio.iscoroutine(res):
coro = res
else:
del res # `res` maybe pywebio.io_ctrl.Output, so need release `res`
except Exception:
self.on_task_exception()
if coro is not None:
if mutex_mode:
await coro
else:
self.run_async(coro)
cls = type(self)
callback_task = Task(callback_coro(), cls.get_current_session())
# Activate task
# Don't callback.step(), it will result in recursive calls to step()
# todo: integrate with inactive_coro_instances
callback_task.coro.send(None)
cls.get_current_session().coros[callback_task.coro_id] = callback_task
self._need_keep_alive = True
return callback_task.coro_id
def run_async(self, coro_obj):
"""异步运行协程对象。可以在协程内调用 PyWebIO 交互函数
:param coro_obj: 协程对象
:return: An instance of `TaskHandler` is returned, which can be used later to close the task.
"""
assert asyncio.iscoroutine(coro_obj), '`run_async()` only accept coroutine object'
self._alive_coro_cnt += 1
task = Task(coro_obj, session=self, on_coro_stop=self._on_task_finish)
self.coros[task.coro_id] = task
asyncio.get_event_loop().call_soon_threadsafe(task.step)
return task.task_handle()
async def run_asyncio_coroutine(self, coro_obj):
"""若会话线程和运行事件的线程不是同一个线程，需要用 asyncio_coroutine 来运行asyncio中的协程"""
assert asyncio.iscoroutine(coro_obj), '`run_asyncio_coroutine()` only accept coroutine object'
res = await WebIOFuture(coro=coro_obj)
return res
def need_keep_alive(self) -> bool:
return self._need_keep_alive
[docs]class TaskHandler:
"""The handler of coroutine task
See also: `run_async() <pywebio.session.run_async>`
"""
def __init__(self, close, closed):
self._close = close
self._closed = closed
[docs] def close(self):
"""Close the coroutine task."""
return self._close()
[docs] def closed(self) -> bool:
"""Returns a bool stating whether the coroutine task is closed. """
return self._closed()
class Task:
@contextmanager
def session_context(self):
"""
>>> with session_context():
... res = self.coros[-1].send(data)
"""
# todo issue: with 语句可能发生嵌套，导致内层with退出时，将属性置空
_context.current_session = self.session
_context.current_task_id = self.coro_id
try:
yield
finally:
_context.current_session = None
_context.current_task_id = None
@staticmethod
def gen_coro_id(coro=None):
"""生成协程id"""
name = 'coro'
if hasattr(coro, '__name__'):
name = coro.__name__
return '%s-%s' % (name, random_str(10))
def __init__(self, coro, session: CoroutineBasedSession, on_coro_stop=None):
"""
:param coro: 协程对象
:param session: 创建该Task的会话实例
:param on_coro_stop: 任务结束(正常结束或外部调用Task.close)时运行的回调
"""
self.session = session
self.coro = coro
self.result = None
self.task_closed = False # 任务完毕/取消
self.on_coro_stop = on_coro_stop or (lambda _: None)
self.coro_id = self.gen_coro_id(self.coro)
self.pending_futures = {} # id(future) -> future
logger.debug('Task[%s] created ', self.coro_id)
def step(self, result=None, throw_exp=False):
"""激活协程
:param any result: 向协程传入的数据
:param bool throw_exp: 是否向协程引发异常，为 True 时， result 参数为相应的异常对象
"""
coro_yield = None
with self.session_context():
try:
if throw_exp:
coro_yield = self.coro.throw(result)
else:
coro_yield = self.coro.send(result)
except StopIteration as e:
if len(e.args) == 1:
self.result = e.args[0]
self.close()
logger.debug('Task[%s] finished', self.coro_id)
except Exception as e:
if not isinstance(e, SessionException):
self.session.on_task_exception()
self.close()
if coro_yield is None:
return
future = None
if isinstance(coro_yield, WebIOFuture):
if coro_yield.coro:
future = asyncio.run_coroutine_threadsafe(coro_yield.coro, asyncio.get_event_loop())
else:
future = coro_yield
if not self.session.closed() and hasattr(future, 'add_done_callback'):
future.add_done_callback(self._wakeup)
self.pending_futures[id(future)] = future
def _wakeup(self, future):
if not future.cancelled():
del self.pending_futures[id(future)]
self.step(future.result())
def close(self):
if self.task_closed:
return
self.task_closed = True
self.coro.close()
while self.pending_futures:
_, f = self.pending_futures.popitem()
f.cancel()
self.on_coro_stop(self)
self.on_coro_stop = None # avoid circular reference
self.session = None
logger.debug('Task[%s] closed', self.coro_id)
def __del__(self):
if not self.task_closed:
logger.warning('Task[%s] was destroyed but it is pending!', self.coro_id)
def task_handle(self):
handle = TaskHandler(close=self.close, closed=lambda: self.task_closed)
return handle