mirror of https://github.com/nocturn9x/giambio.git
399 lines
14 KiB
Python
399 lines
14 KiB
Python
"""
|
|
The main runtime environment for giambio
|
|
|
|
Copyright (C) 2020 nocturn9x
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
"""
|
|
|
|
# Import libraries and internal resources
|
|
import types
|
|
import socket
|
|
from time import sleep as wait
|
|
from timeit import default_timer
|
|
from .objects import Task, TimeQueue
|
|
from socket import SOL_SOCKET, SO_ERROR
|
|
from .traps import want_read, want_write
|
|
from collections import deque
|
|
from .socket import AsyncSocket, WantWrite, WantRead
|
|
from selectors import DefaultSelector, EVENT_READ, EVENT_WRITE
|
|
from .exceptions import (InternalError,
|
|
CancelledError,
|
|
ResourceBusy,
|
|
)
|
|
|
|
|
|
|
|
class AsyncScheduler:
|
|
"""
|
|
An asynchronous scheduler implementation. Tries to mimic the threaded
|
|
model in its simplicity, without using actual threads, but rather alternating
|
|
across coroutines execution to let more than one thing at a time to proceed
|
|
with its calculations. An attempt to fix the threaded model has been made
|
|
without making the API unnecessarily complicated.
|
|
A few examples are tasks cancellation and exception propagation.
|
|
"""
|
|
|
|
def __init__(self):
|
|
"""
|
|
Object constructor
|
|
"""
|
|
|
|
# Tasks that are ready to run
|
|
self.tasks = deque()
|
|
# Selector object to perform I/O multiplexing
|
|
self.selector = DefaultSelector()
|
|
# This will always point to the currently running coroutine (Task object)
|
|
self.current_task = None
|
|
# Monotonic clock to keep track of elapsed time reliably
|
|
self.clock = default_timer
|
|
# Tasks that are asleep
|
|
self.paused = TimeQueue(self.clock)
|
|
# All active Event objects
|
|
self.events = set()
|
|
# Data to send back to a trap
|
|
self.to_send = None
|
|
# Have we ever ran?
|
|
self.has_ran = False
|
|
|
|
def done(self):
|
|
"""
|
|
Returns True if there is work to do
|
|
"""
|
|
|
|
if self.selector.get_map() or any([self.paused,
|
|
self.tasks,
|
|
self.events
|
|
]):
|
|
return False
|
|
return True
|
|
|
|
def shutdown(self):
|
|
"""
|
|
Shuts down the event loop
|
|
"""
|
|
|
|
# TODO: See if other teardown is required (massive join()?)
|
|
self.selector.close()
|
|
|
|
def run(self):
|
|
"""
|
|
Starts the loop and 'listens' for events until there is work to do,
|
|
then exits. This behavior kinda reflects a kernel, as coroutines can
|
|
request the loop's functionality only trough some fixed entry points,
|
|
which in turn yield and give execution control to the loop itself.
|
|
"""
|
|
|
|
while True:
|
|
try:
|
|
if self.done():
|
|
self.shutdown()
|
|
break
|
|
elif not self.tasks:
|
|
if self.paused:
|
|
# If there are no actively running tasks
|
|
# we try to schedule the asleep ones
|
|
self.awake_sleeping()
|
|
if self.selector.get_map():
|
|
# The next step is checking for I/O
|
|
self.check_io()
|
|
if self.events:
|
|
# Try to awake event-waiting tasks
|
|
self.check_events()
|
|
# While there are tasks to run
|
|
while self.tasks:
|
|
# Sets the currently running task
|
|
self.current_task = self.tasks.popleft()
|
|
if self.current_task.cancel_pending:
|
|
self.do_cancel()
|
|
if self.to_send and self.current_task.status != "init":
|
|
data = self.to_send
|
|
else:
|
|
data = None
|
|
# Run a single step with the calculation
|
|
method, *args = self.current_task.run(data)
|
|
self.current_task.status = "run"
|
|
self.current_task.steps += 1
|
|
# Data has been sent, reset it to None
|
|
if self.to_send and self.current_task != "init":
|
|
self.to_send = None
|
|
# Sneaky method call, thanks to David Beazley for this ;)
|
|
getattr(self, method)(*args)
|
|
except AttributeError: # If this happens, that's quite bad!
|
|
raise InternalError("Uh oh! Something very bad just happened, did"
|
|
" you try to mix primitives from other async libraries?") from None
|
|
except CancelledError:
|
|
self.current_task.status = "cancelled"
|
|
self.current_task.cancelled = True
|
|
self.current_task.cancel_pending = False
|
|
self.join() # TODO: Investigate if a call to join() is needed
|
|
except StopIteration as ret:
|
|
# Coroutine ends
|
|
self.current_task.status = "end"
|
|
self.current_task.result = ret.value
|
|
self.current_task.finished = True
|
|
self.join()
|
|
except BaseException as err:
|
|
self.current_task.exc = err
|
|
self.current_task.status = "crashed"
|
|
self.join()
|
|
|
|
def do_cancel(self):
|
|
"""
|
|
Performs task cancellation by throwing CancelledError inside the current
|
|
task in order to stop it from executing. The loop continues to execute
|
|
as tasks are independent
|
|
"""
|
|
|
|
# TODO: Do we need anything else?
|
|
self.current_task.throw(CancelledError)
|
|
|
|
def get_running(self):
|
|
"""
|
|
Returns the current task
|
|
"""
|
|
|
|
self.tasks.append(self.current_task)
|
|
self.to_send = self.current_task
|
|
|
|
def check_events(self):
|
|
"""
|
|
Checks for ready or expired events and triggers them
|
|
"""
|
|
|
|
for event in self.events.copy():
|
|
if event.set:
|
|
event.event_caught = True
|
|
event.waiters
|
|
self.tasks.extend(event.waiters)
|
|
self.events.remove(event)
|
|
|
|
def awake_sleeping(self):
|
|
"""
|
|
Checks for and reschedules sleeping tasks
|
|
"""
|
|
|
|
wait(max(0.0, self.paused[0][0] - self.clock()))
|
|
# Sleep until the closest deadline in order not to waste CPU cycles
|
|
while self.paused[0][0] < self.clock():
|
|
# Reschedules tasks when their deadline has elapsed
|
|
self.tasks.append(self.paused.get())
|
|
if not self.paused:
|
|
break
|
|
|
|
def check_io(self):
|
|
"""
|
|
Checks and schedules task to perform I/O
|
|
"""
|
|
|
|
if self.tasks or self.events: # If there are tasks or events, never wait
|
|
timeout = 0.0
|
|
elif self.paused: # If there are asleep tasks, wait until the closest
|
|
# deadline
|
|
timeout = max(0.0, self.paused[0][0] - self.clock())
|
|
else:
|
|
timeout = None # If we _only_ have I/O to do, then wait indefinitely
|
|
for key in dict(self.selector.get_map()).values():
|
|
# We make sure we don't reschedule finished tasks
|
|
if key.data.finished:
|
|
key.data.last_io = ()
|
|
self.selector.unregister(key.fileobj)
|
|
if self.selector.get_map(): # If there is indeed tasks waiting on I/O
|
|
io_ready = self.selector.select(timeout)
|
|
# Get sockets that are ready and schedule their tasks
|
|
for key, _ in io_ready:
|
|
self.tasks.append(key.data) # Resource ready? Schedule its task
|
|
|
|
def start(self, func: types.FunctionType, *args):
|
|
"""
|
|
Starts the event loop from a sync context
|
|
"""
|
|
|
|
entry = Task(func(*args), func.__name__ or str(func))
|
|
self.tasks.append(entry)
|
|
self.run()
|
|
self.has_ran = True
|
|
if entry.exc:
|
|
raise entry.exc from None
|
|
|
|
def reschedule_joinee(self):
|
|
"""
|
|
Reschedules the joinee(s) of the
|
|
currently running task, if any
|
|
"""
|
|
|
|
self.tasks.extend(self.current_task.waiters)
|
|
|
|
def join(self):
|
|
"""
|
|
Handler for the 'join' event, does some magic to tell the scheduler
|
|
to wait until the current coroutine ends
|
|
"""
|
|
|
|
child = self.current_task
|
|
child.joined = True
|
|
if child.parent:
|
|
child.waiters.append(child.parent)
|
|
if child.finished:
|
|
self.reschedule_joinee()
|
|
elif child.exc:
|
|
... # TODO: Handle exceptions
|
|
|
|
def sleep(self, seconds: int or float):
|
|
"""
|
|
Puts the caller to sleep for a given amount of seconds
|
|
"""
|
|
|
|
if seconds:
|
|
self.current_task.status = "sleep"
|
|
self.paused.put(self.current_task, seconds)
|
|
else:
|
|
self.tasks.append(self.current_task)
|
|
|
|
# TODO: More generic I/O rather than just sockets
|
|
def want_read(self, sock: socket.socket):
|
|
"""
|
|
Handler for the 'want_read' event, registers the socket inside the
|
|
selector to perform I/0 multiplexing
|
|
"""
|
|
|
|
self.current_task.status = "I/O"
|
|
if self.current_task.last_io:
|
|
if self.current_task.last_io == ("READ", sock):
|
|
# Socket is already scheduled!
|
|
return
|
|
else:
|
|
self.selector.unregister(sock)
|
|
self.current_task.last_io = "READ", sock
|
|
try:
|
|
self.selector.register(sock, EVENT_READ, self.current_task)
|
|
except KeyError:
|
|
# The socket is already registered doing something else
|
|
raise ResourceBusy("The given resource is busy!") from None
|
|
|
|
def want_write(self, sock: socket.socket):
|
|
"""
|
|
Handler for the 'want_write' event, registers the socket inside the
|
|
selector to perform I/0 multiplexing
|
|
"""
|
|
|
|
self.current_task.status = "I/O"
|
|
if self.current_task.last_io:
|
|
if self.current_task.last_io == ("WRITE", sock):
|
|
# Socket is already scheduled!
|
|
return
|
|
else:
|
|
# TODO: Inspect why modify() causes issues
|
|
self.selector.unregister(sock)
|
|
self.current_task.last_io = "WRITE", sock
|
|
try:
|
|
self.selector.register(sock, EVENT_WRITE, self.current_task)
|
|
except KeyError:
|
|
raise ResourceBusy("The given resource is busy!") from None
|
|
|
|
def event_set(self, event):
|
|
"""
|
|
Sets an event
|
|
"""
|
|
|
|
self.events.add(event)
|
|
event.waiters.append(self.current_task)
|
|
event.set = True
|
|
self.reschedule_joinee()
|
|
|
|
def event_wait(self, event):
|
|
"""
|
|
Pauses the current task on an event
|
|
"""
|
|
|
|
event.waiters.append(self.current_task)
|
|
|
|
|
|
def cancel(self):
|
|
"""
|
|
Handler for the 'cancel' event, schedules the task to be cancelled later
|
|
or does so straight away if it is safe to do so
|
|
"""
|
|
|
|
if self.current_task.status in ("I/O", "sleep"):
|
|
# We cancel right away
|
|
self.do_cancel()
|
|
else:
|
|
self.current_task.cancel_pending = True # Cancellation is deferred
|
|
|
|
def wrap_socket(self, sock):
|
|
"""
|
|
Wraps a standard socket into an AsyncSocket object
|
|
"""
|
|
|
|
return AsyncSocket(sock, self)
|
|
|
|
async def read_sock(self, sock: socket.socket, buffer: int):
|
|
"""
|
|
Reads from a socket asynchronously, waiting until the resource is
|
|
available and returning up to buffer bytes from the socket
|
|
"""
|
|
|
|
try:
|
|
return sock.recv(buffer)
|
|
except WantRead:
|
|
await want_read(sock)
|
|
return sock.recv(buffer)
|
|
|
|
async def accept_sock(self, sock: socket.socket):
|
|
"""
|
|
Accepts a socket connection asynchronously, waiting until the resource
|
|
is available and returning the result of the accept() call
|
|
"""
|
|
|
|
try:
|
|
return sock.accept()
|
|
except WantRead:
|
|
await want_read(sock)
|
|
return sock.accept()
|
|
|
|
async def sock_sendall(self, sock: socket.socket, data: bytes):
|
|
"""
|
|
Sends all the passed data, as bytes, trough the socket asynchronously
|
|
"""
|
|
|
|
while data:
|
|
try:
|
|
sent_no = sock.send(data)
|
|
except WantWrite:
|
|
await want_write(sock)
|
|
sent_no = sock.send(data)
|
|
data = data[sent_no:]
|
|
|
|
async def close_sock(self, sock: socket.socket):
|
|
"""
|
|
Closes the socket asynchronously
|
|
"""
|
|
|
|
await want_write(sock)
|
|
self.selector.unregister(sock)
|
|
return sock.close()
|
|
|
|
async def connect_sock(self, sock: socket.socket, addr: tuple):
|
|
"""
|
|
Connects a socket asynchronously
|
|
"""
|
|
|
|
try: # "Borrowed" from curio
|
|
return sock.connect(addr)
|
|
except WantWrite:
|
|
await want_write(sock)
|
|
err = sock.getsockopt(SOL_SOCKET, SO_ERROR)
|
|
if err != 0:
|
|
raise OSError(err, f"Connect call failed: {addr}")
|