mirror of https://github.com/nocturn9x/giambio.git
Attempt to reimplement TaskManager, exceptions not working
This commit is contained in:
parent
1b958b0341
commit
d16c0932ac
|
@ -3,5 +3,6 @@ __version__ = (0, 0, 1)
|
||||||
from ._core import AsyncScheduler
|
from ._core import AsyncScheduler
|
||||||
from .exceptions import GiambioError, AlreadyJoinedError, CancelledError
|
from .exceptions import GiambioError, AlreadyJoinedError, CancelledError
|
||||||
from ._traps import sleep
|
from ._traps import sleep
|
||||||
|
from ._managers import TaskManager
|
||||||
|
|
||||||
__all__ = ["AsyncScheduler", "GiambioError", "AlreadyJoinedError", "CancelledError", "TaskManager", "sleep"]
|
__all__ = ["AsyncScheduler", "GiambioError", "AlreadyJoinedError", "CancelledError", "TaskManager", "sleep"]
|
||||||
|
|
|
@ -1,5 +1,5 @@
|
||||||
import types
|
import types
|
||||||
from collections import deque, defaultdict
|
from collections import deque
|
||||||
from selectors import DefaultSelector, EVENT_READ, EVENT_WRITE
|
from selectors import DefaultSelector, EVENT_READ, EVENT_WRITE
|
||||||
from heapq import heappush, heappop
|
from heapq import heappush, heappop
|
||||||
import socket
|
import socket
|
||||||
|
@ -24,7 +24,7 @@ class AsyncScheduler:
|
||||||
self.paused = [] # Sleeping tasks
|
self.paused = [] # Sleeping tasks
|
||||||
self.selector = DefaultSelector() # Selector object to perform I/O multiplexing
|
self.selector = DefaultSelector() # Selector object to perform I/O multiplexing
|
||||||
self.running = None # This will always point to the currently running coroutine (Task object)
|
self.running = None # This will always point to the currently running coroutine (Task object)
|
||||||
self.joined = defaultdict(list) # Tasks that want to join
|
self.joined = {} # Tasks that want to join
|
||||||
self.clock = default_timer # Monotonic clock to keep track of elapsed time
|
self.clock = default_timer # Monotonic clock to keep track of elapsed time
|
||||||
self.sequence = 0 # To avoid TypeError in the (unlikely) event of two task with the same deadline we use a unique and incremental integer pushed to the queue together with the deadline and the function itself
|
self.sequence = 0 # To avoid TypeError in the (unlikely) event of two task with the same deadline we use a unique and incremental integer pushed to the queue together with the deadline and the function itself
|
||||||
|
|
||||||
|
@ -52,9 +52,16 @@ class AsyncScheduler:
|
||||||
method, *args = self.running.run()
|
method, *args = self.running.run()
|
||||||
getattr(self, method)(*args) # Sneaky method call, thanks to David Beazley for this ;)
|
getattr(self, method)(*args) # Sneaky method call, thanks to David Beazley for this ;)
|
||||||
except StopIteration as e:
|
except StopIteration as e:
|
||||||
self.to_run.extend(self.joined.pop(self.running, ())) # Reschedules the parent task
|
e = e.args[0] if e.args else None
|
||||||
|
self.running.result = e
|
||||||
|
self.running.finished = True
|
||||||
|
self.reschedule_parent()
|
||||||
except CancelledError:
|
except CancelledError:
|
||||||
... # What to do here?
|
self.running.cancelled = True
|
||||||
|
self.reschedule_parent()
|
||||||
|
except Exception as error:
|
||||||
|
self.running.exc = error
|
||||||
|
self.reschedule_parent()
|
||||||
|
|
||||||
def start(self, coro: types.coroutine):
|
def start(self, coro: types.coroutine):
|
||||||
"""Starts the event loop using a coroutine as an entry point.
|
"""Starts the event loop using a coroutine as an entry point.
|
||||||
|
@ -64,6 +71,12 @@ class AsyncScheduler:
|
||||||
self.to_run.append(Task(coro))
|
self.to_run.append(Task(coro))
|
||||||
self.run()
|
self.run()
|
||||||
|
|
||||||
|
def reschedule_parent(self):
|
||||||
|
"""Reschedules the parent task"""
|
||||||
|
|
||||||
|
popped = self.joined.pop(self.running, None)
|
||||||
|
if popped:
|
||||||
|
self.to_run.append(popped)
|
||||||
|
|
||||||
def want_read(self, sock: socket.socket):
|
def want_read(self, sock: socket.socket):
|
||||||
"""Handler for the 'want_read' event, registers the socket inside the selector to perform I/0 multiplexing"""
|
"""Handler for the 'want_read' event, registers the socket inside the selector to perform I/0 multiplexing"""
|
||||||
|
@ -118,7 +131,7 @@ class AsyncScheduler:
|
||||||
|
|
||||||
|
|
||||||
if coro not in self.joined:
|
if coro not in self.joined:
|
||||||
self.joined[coro].append(self.running)
|
self.joined[coro] = self.running
|
||||||
else:
|
else:
|
||||||
raise AlreadyJoinedError("Joining the same task multiple times is not allowed!")
|
raise AlreadyJoinedError("Joining the same task multiple times is not allowed!")
|
||||||
|
|
||||||
|
@ -132,7 +145,7 @@ class AsyncScheduler:
|
||||||
def cancel(self, task):
|
def cancel(self, task):
|
||||||
"""Cancels a task"""
|
"""Cancels a task"""
|
||||||
|
|
||||||
self.running.coroutine.throw(CancelledError(task))
|
task.coroutine.throw(CancelledError)
|
||||||
|
|
||||||
async def connect_sock(self, sock: socket.socket, addr: tuple):
|
async def connect_sock(self, sock: socket.socket, addr: tuple):
|
||||||
"""Connects a socket asynchronously"""
|
"""Connects a socket asynchronously"""
|
||||||
|
|
|
@ -1,6 +1,6 @@
|
||||||
import types
|
import types
|
||||||
from ._traps import join, sleep, cancel
|
from ._traps import join, sleep, cancel
|
||||||
from .exceptions import CancelledError
|
|
||||||
|
|
||||||
class Task:
|
class Task:
|
||||||
|
|
||||||
|
@ -8,8 +8,10 @@ class Task:
|
||||||
|
|
||||||
def __init__(self, coroutine: types.coroutine):
|
def __init__(self, coroutine: types.coroutine):
|
||||||
self.coroutine = coroutine
|
self.coroutine = coroutine
|
||||||
self.joined = False # True if the task is joined
|
|
||||||
self.cancelled = False # True if the task gets cancelled
|
self.cancelled = False # True if the task gets cancelled
|
||||||
|
self.exc = None
|
||||||
|
self.result = None
|
||||||
|
self.finished = False
|
||||||
|
|
||||||
def run(self):
|
def run(self):
|
||||||
"""Simple abstraction layer over the coroutines ``send`` method"""
|
"""Simple abstraction layer over the coroutines ``send`` method"""
|
||||||
|
@ -26,3 +28,7 @@ class Task:
|
||||||
|
|
||||||
await cancel(self)
|
await cancel(self)
|
||||||
|
|
||||||
|
def __repr__(self):
|
||||||
|
"""Implements repr(self)"""
|
||||||
|
|
||||||
|
return f"Task({self.coroutine}, cancelled={self.cancelled}, exc={repr(self.exc)}, result={self.result}, finished={self.finished})"
|
||||||
|
|
|
@ -0,0 +1,99 @@
|
||||||
|
from collections import deque
|
||||||
|
import types
|
||||||
|
from ._layers import Task
|
||||||
|
from heapq import heappush
|
||||||
|
from ._traps import sleep
|
||||||
|
import time
|
||||||
|
|
||||||
|
|
||||||
|
class TaskManager:
|
||||||
|
"""The only way to execute asynchronous code in giambio is trough a ``TaskManager`` (or one of its children classes) object used within
|
||||||
|
an ``async with`` context manager. The ``TaskManager`` is an ideal "playground" where all asynchronous code runs and where giambio's
|
||||||
|
event loop can control their execution flow.
|
||||||
|
|
||||||
|
The key feature of this mechanism is that all tasks are always joined automatically: This opens a new world of features,
|
||||||
|
allowing exceptions to propagate just as expected (exceptions are **never** discarded in giambio, unlike in some other libraries) and some other lower-level advantages.
|
||||||
|
Moreover, giambio always saves the return values so that you don't lose any important information when executing a coroutine.
|
||||||
|
|
||||||
|
There are a few concepts to explain here, though:
|
||||||
|
|
||||||
|
- The term "task" refers to a coroutine executed trough the ``TaskManager``'s methods ``spawn()`` and ``schedule()``, as well as
|
||||||
|
one executed with ``await coro()``
|
||||||
|
- If an exception occurs, all other tasks are cancelled (read more below) and the exception is later propagated in the parent task
|
||||||
|
- The concept of cancellation is a bit tricky, because there is no real way to stop a coroutine from executing without actually raising
|
||||||
|
an exception inside i. So when giambio needs to cancel a task, it just throws ``giambio.exceptions.CancelledError`` inside it and hopes for the best.
|
||||||
|
This exception inherits from ``BaseException``, which by convention means that it should not be catched. Doing so in giambio will likely break your code
|
||||||
|
and make it explode spectacularly. If you really want to catch it to perform cleanup, be sure to re-raise it when done (or to raise another unhandled exception if you want)
|
||||||
|
so that the internal loop can proceed with execution.
|
||||||
|
In general, when writing an asynchronous function, you should always consider that it might be cancelled at any time and handle that case accordingly.
|
||||||
|
"""
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
def __init__(self, loop):
|
||||||
|
self.values = {} # Results from each task
|
||||||
|
self.loop = loop # The event loop that spawned the TaskManager
|
||||||
|
|
||||||
|
async def _cancel_and_raise(self, exc):
|
||||||
|
"""Cancels all the tasks inside the TaskManager object and raises the exception
|
||||||
|
of the task that triggered this mechanism"""
|
||||||
|
|
||||||
|
try:
|
||||||
|
await self.loop.running.cancel()
|
||||||
|
except Exception as error:
|
||||||
|
self.loop.running.exc = error
|
||||||
|
for task in self.loop.to_run + deque(self.loop.paused):
|
||||||
|
if isinstance(task, tuple): # Sleeping task
|
||||||
|
_, _, task = task
|
||||||
|
try:
|
||||||
|
await task.cancel()
|
||||||
|
except Exception as error:
|
||||||
|
task.exc = error
|
||||||
|
raise exc
|
||||||
|
|
||||||
|
async def __aenter__(self):
|
||||||
|
return self
|
||||||
|
|
||||||
|
async def __aexit__(self, type, value, traceback):
|
||||||
|
while True:
|
||||||
|
if not any([self.loop.to_run, self.loop.paused]):
|
||||||
|
break
|
||||||
|
tasks = self.loop.to_run + deque(self.loop.paused)
|
||||||
|
task = tasks.popleft()
|
||||||
|
if isinstance(task, tuple): # Sleeping task
|
||||||
|
_, _, task = task
|
||||||
|
self.values[task] = await task.join()
|
||||||
|
if task.exc:
|
||||||
|
print(task)
|
||||||
|
await self._cancel_and_raise(task.exc)
|
||||||
|
|
||||||
|
def spawn(self, coroutine: types.coroutine):
|
||||||
|
"""Schedules a task for execution, appending it to the call stack
|
||||||
|
|
||||||
|
:param coroutine: The coroutine to spawn, please note that if you want to execute foo, you need to pass foo() as this
|
||||||
|
returns a coroutine instead of a function object
|
||||||
|
:type coroutine: types.coroutine
|
||||||
|
:returns: A ``Task`` object
|
||||||
|
:rtype: class: Task
|
||||||
|
"""
|
||||||
|
|
||||||
|
task = Task(coroutine)
|
||||||
|
self.loop.to_run.append(task)
|
||||||
|
return task
|
||||||
|
|
||||||
|
def schedule(self, coroutine: types.coroutine, n: int):
|
||||||
|
"""Schedules a task for execution after when seconds
|
||||||
|
|
||||||
|
:param coroutine: The coroutine to spawn, please note that if you want to execute foo, you need to pass foo() as this
|
||||||
|
returns a coroutine instead of a function object
|
||||||
|
:type coroutine: types.coroutine
|
||||||
|
:param n: The delay in seconds after which the task should start running
|
||||||
|
:type n: int
|
||||||
|
:returns: A ``Task`` object
|
||||||
|
:rtype: class: Task
|
||||||
|
"""
|
||||||
|
|
||||||
|
self.loop.sequence += 1
|
||||||
|
task = Task(coroutine)
|
||||||
|
heappush(self.loop.paused, (self.loop.clock() + n, self.loop.sequence, task))
|
||||||
|
return task
|
|
@ -0,0 +1,8 @@
|
||||||
|
from ._core import AsyncScheduler
|
||||||
|
from types import coroutine
|
||||||
|
|
||||||
|
|
||||||
|
def run(coro: coroutine):
|
||||||
|
"""Shorthand for giambio.AsyncScheduler().start(coro)"""
|
||||||
|
|
||||||
|
... # How to do it? (Share objects between coroutines etc)
|
|
@ -24,18 +24,16 @@ def sleep(seconds: int):
|
||||||
yield "sleep", seconds
|
yield "sleep", seconds
|
||||||
|
|
||||||
@types.coroutine
|
@types.coroutine
|
||||||
def join(task, silent=False):
|
def join(task):
|
||||||
"""'Tells' the scheduler that the desired task MUST be awaited for completion
|
"""'Tells' the scheduler that the desired task MUST be awaited for completion
|
||||||
If silent is True, any exception in the child task will be discarded
|
|
||||||
|
|
||||||
:param task: The task to join
|
:param task: The task to join
|
||||||
:type task: class: Task
|
:type task: class: Task
|
||||||
:param silent: If ``True``, any exception raised from the child will be ignored (not recommended), defaults to ``False``
|
|
||||||
:type silent: bool, optional
|
|
||||||
"""
|
"""
|
||||||
|
|
||||||
return (yield "join", task)
|
yield "join", task
|
||||||
|
assert task.finished
|
||||||
|
return task.result
|
||||||
|
|
||||||
@types.coroutine
|
@types.coroutine
|
||||||
def cancel(task):
|
def cancel(task):
|
||||||
|
@ -49,7 +47,7 @@ def cancel(task):
|
||||||
"""
|
"""
|
||||||
|
|
||||||
yield "cancel", task
|
yield "cancel", task
|
||||||
|
assert task.cancelled
|
||||||
|
|
||||||
@types.coroutine
|
@types.coroutine
|
||||||
def want_read(sock: socket.socket):
|
def want_read(sock: socket.socket):
|
||||||
|
|
|
@ -1,4 +1,4 @@
|
||||||
from giambio import AsyncScheduler, sleep, CancelledError
|
from giambio import AsyncScheduler, sleep, TaskManager
|
||||||
import time
|
import time
|
||||||
|
|
||||||
|
|
||||||
|
@ -7,6 +7,8 @@ async def countdown(n: int):
|
||||||
print(f"Down {n}")
|
print(f"Down {n}")
|
||||||
n -= 1
|
n -= 1
|
||||||
await sleep(1)
|
await sleep(1)
|
||||||
|
if n == 5:
|
||||||
|
raise ValueError('lul')
|
||||||
print("Countdown over")
|
print("Countdown over")
|
||||||
|
|
||||||
|
|
||||||
|
@ -20,14 +22,10 @@ async def countup(stop, step: int or float = 1):
|
||||||
|
|
||||||
|
|
||||||
async def main():
|
async def main():
|
||||||
counter = scheduler.create_task(countup(5, 4))
|
async with TaskManager(scheduler) as manager:
|
||||||
counter2 = scheduler.create_task(countdown(20))
|
manager.spawn(countdown(10))
|
||||||
print("Counters started, awaiting completion")
|
manager.spawn(countup(5, 2))
|
||||||
await sleep(4)
|
print("Counters started, awaiting completion")
|
||||||
print("4 seconds have passed, killing countup task")
|
|
||||||
await counter.cancel()
|
|
||||||
await counter.join()
|
|
||||||
await counter2.join()
|
|
||||||
print("Task execution complete")
|
print("Task execution complete")
|
||||||
|
|
||||||
if __name__ == "__main__":
|
if __name__ == "__main__":
|
||||||
|
|
Loading…
Reference in New Issue