mirror of https://github.com/nocturn9x/giambio.git
242 lines
8.5 KiB
Python
242 lines
8.5 KiB
Python
import types
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import datetime
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from collections import deque, defaultdict
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from selectors import DefaultSelector, EVENT_READ, EVENT_WRITE
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from heapq import heappush, heappop
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import socket
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from .exceptions import AlreadyJoinedError, CancelledError
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import traceback
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from timeit import default_timer
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from time import sleep as wait
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class Task:
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"""A simple wrapper around a coroutine object"""
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def __init__(self, coroutine: types.coroutine):
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self.coroutine = coroutine
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self.status = False # Not ran yet
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self.joined = False
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self.ret_val = None # Return value is saved here
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self.exception = None # If errored, the exception is saved here
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self.cancelled = False # When cancelled, this is True
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def run(self):
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self.status = True
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return self.coroutine.send(None)
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def __repr__(self):
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return f"giambio.core.Task({self.coroutine}, {self.status}, {self.joined}, {self.ret_val}, {self.exception}, {self.cancelled})"
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async def cancel(self):
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return await cancel(self)
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async def join(self):
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return await join(self)
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class EventLoop:
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"""Implementation of an event loop, alternates between execution of coroutines (asynchronous functions)
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to allow a concurrency model or 'green threads'"""
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def __init__(self):
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"""Object constructor"""
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self.to_run = deque() # Scheduled tasks
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self.paused = [] # Sleeping tasks
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self.selector = DefaultSelector() # Selector object to perform I/O multiplexing
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self.running = None # This will always point to the currently running coroutine (Task object)
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self.joined = defaultdict(list) # Tasks that want to join
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self.clock = default_timer # Monotonic clock to keep track of elapsed time
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def loop(self):
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"""Main event loop for giambio"""
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while True:
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if not self.selector.get_map() and not self.to_run:
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break
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while self.selector.get_map(): # If there are sockets ready, (re)schedule their associated task
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timeout = 0.0 if self.to_run else None
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tasks = deque(self.selector.select(timeout))
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for key, _ in tasks:
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self.to_run.append(key.data) # Socket ready? Schedule the task
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self.selector.unregister(key.fileobj) # Once (re)scheduled, the task does not need to perform I/O multiplexing (for now)
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while self.to_run or self.paused:
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if not self.to_run:
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wait(max(0.0, self.paused[0][0] - self.clock())) # If there are no tasks ready, just do nothing
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while self.paused and self.paused[0][0] < self.clock(): # Reschedules task when their timer has elapsed
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_, coro = heappop(self.paused)
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self.to_run.append(coro)
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self.running = self.to_run.popleft() # Sets the currently running task
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try:
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method, *args = self.running.run() # Sneaky method call, thanks to David Beazley for this ;)
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getattr(self, method)(*args)
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except StopIteration as e:
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self.running.ret_value = e.args[0] if e.args else None # Saves the return value
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self.to_run.extend(self.joined.pop(self.running, ())) # Reschedules the parent task
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except CancelledError:
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self.running.cancelled = True # Update the coroutine status
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raise
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except Exception as has_raised:
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self.to_run.extend(self.joined.pop(self.running, ())) # Reschedules the parent task
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if self.running.joined: # Let the join function handle the hassle of propagating the error
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self.running.exception = has_raised # Save the exception
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else: # Let the exception propagate (I'm looking at you asyncIO ;))
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raise
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except KeyboardInterrupt:
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self.running.coroutine.throw(KeyboardInterrupt)
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def spawn(self, coroutine: types.coroutine):
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"""Schedules a task for execution, appending it to the call stack"""
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task = Task(coroutine)
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self.to_run.append(task)
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return task
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def start(self, coroutine: types.coroutine, *args, **kwargs):
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self.spawn(coroutine(*args, **kwargs))
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self.loop()
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def want_read(self, sock: socket.socket):
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"""Handler for the 'want_read' event, performs the needed operations to read from the passed socket
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asynchronously"""
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self.selector.register(sock, EVENT_READ, self.running)
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def want_write(self, sock: socket.socket):
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"""Handler for the 'want_write' event, performs the needed operations to write into the passed socket
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asynchronously"""
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self.selector.register(sock, EVENT_WRITE, self.running)
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def wrap_socket(self, sock):
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return AsyncSocket(sock, self)
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async def read_sock(self, sock: socket.socket, buffer: int):
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await want_read(sock)
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return sock.recv(buffer)
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async def accept_sock(self, sock: socket.socket):
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await want_read(sock)
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return sock.accept()
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async def sock_sendall(self, sock: socket.socket, data: bytes):
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while data:
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await want_write(sock)
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sent_no = sock.send(data)
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data = data[sent_no:]
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async def close_sock(self, sock: socket.socket):
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await want_write(sock)
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return sock.close()
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def want_join(self, coro: types.coroutine):
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if coro not in self.joined:
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self.joined[coro].append(self.running)
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else:
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raise AlreadyJoinedError("Joining the same task multiple times is not allowed!")
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def want_sleep(self, seconds):
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heappush(self.paused, (self.clock() + seconds, self.running))
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def want_cancel(self, task):
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task.coroutine.throw(CancelledError)
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async def connect_sock(self, sock: socket.socket, addr: tuple):
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await want_write(sock)
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return sock.connect(addr)
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class AsyncSocket(object):
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"""Abstraction layer for asynchronous sockets"""
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def __init__(self, sock: socket.socket, loop: EventLoop):
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self.sock = sock
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self.sock.setblocking(False)
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self.loop = loop
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async def receive(self, max_size: int):
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"""Receives up to max_size from a socket asynchronously"""
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return await self.loop.read_sock(self.sock, max_size)
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async def accept(self):
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"""Accepts the socket, completing the 3-step TCP handshake asynchronously"""
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to_wrap = await self.loop.accept_sock(self.sock)
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return self.loop.wrap_socket(to_wrap[0]), to_wrap[1]
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async def send_all(self, data: bytes):
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"""Sends all data inside the buffer asynchronously until it is empty"""
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return await self.loop.sock_sendall(self.sock, data)
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async def close(self):
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"""Closes the socket asynchronously"""
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await self.loop.close_sock(self.sock)
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async def connect(self, addr: tuple):
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"""Connects the socket to an endpoint"""
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await self.loop.connect_sock(self.sock, addr)
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def __enter__(self):
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return self.sock.__enter__()
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def __exit__(self, *args):
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return self.sock.__exit__(*args)
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def __repr__(self):
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return f"AsyncSocket({self.sock}, {self.loop})"
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@types.coroutine
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def sleep(seconds: int):
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"""Pause the execution of a coroutine for the passed amount of seconds,
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without blocking the entire event loop, which keeps watching for other events"""
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yield "want_sleep", seconds
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@types.coroutine
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def want_read(sock: socket.socket):
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"""'Tells' the event loop that there is some coroutine that wants to read from the passed socket"""
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yield "want_read", sock
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@types.coroutine
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def want_write(sock: socket.socket):
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"""'Tells' the event loop that there is some coroutine that wants to write into the passed socket"""
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yield "want_write", sock
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@types.coroutine
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def join(task: Task):
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"""'Tells' the scheduler that the desired task MUST be awaited for completion"""
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task.joined = True
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yield "want_join", task
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if task.exception:
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print("Traceback (most recent call last):")
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traceback.print_tb(task.exception.__traceback__)
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exception_name = type(task.exception).__name__
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if str(task.exception):
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print(f"{exception_name}: {task.exception}")
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else:
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print(task.exception)
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raise task.exception
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return task.ret_val
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@types.coroutine
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def cancel(task: Task):
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yield "want_cancel", task
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assert task.cancelled
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