mirror of https://github.com/nocturn9x/giambio.git
164 lines
7.2 KiB
Python
164 lines
7.2 KiB
Python
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import types
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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, GiambioError
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from timeit import default_timer
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from time import sleep as wait
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from .socket import AsyncSocket, WantRead, WantWrite
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from .abstractions import Task, Result
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from socket import SOL_SOCKET, SO_ERROR
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from .traps import _join, _sleep, _want_read, _want_write, _cancel
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from .util import TaskManager
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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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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
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self._exiting = False
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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 any((self.to_run + deque(self.paused))):
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break
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while not self.to_run: # 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 = 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()
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getattr(self, method)(*args) # Sneaky method call, thanks to David Beazley for this ;)
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self.running.steps += 1
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except StopIteration as e:
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self.running.execution = "FINISH"
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self.running.result = Result(e.args[0] if e.args else None, 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 RuntimeError:
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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.execution = "CANCELLED"
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self.to_run.extend(self.joined.pop(self.running, ()))
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except Exception as err:
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if not self._exiting:
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self.running.execution = "ERRORED"
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self.running.result = Result(None, err)
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self.to_run.extend(self.joined.pop(self.running, ())) # Reschedules the parent task
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else:
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raise
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except KeyboardInterrupt:
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self.running.throw(KeyboardInterrupt)
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def start(self, coroutine: types.coroutine, *args, **kwargs):
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"""Starts the event loop"""
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TaskManager(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, registers the socket inside the selector to perform I/0 multiplexing"""
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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, registers the socket inside the selector to perform I/0 multiplexing"""
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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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"""Wraps a standard socket into an AsyncSocket object"""
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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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"""Reads from a socket asynchronously, waiting until the resource is available and returning up to buffer bytes
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from the socket
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"""
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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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"""Accepts a socket connection asynchronously, waiting until the resource is available and returning the
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result of the accept() call
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"""
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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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"""Sends all the passed data, as bytes, trough the socket asynchronously"""
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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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"""Closes the socket asynchronously"""
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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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"""Handler for the 'want_join' event, does some magic to tell the scheduler
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to wait until the passed coroutine ends. The result of this call equals whatever the
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coroutine returns or, if an exception gets raised, the exception will get propagated inside the
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parent task"""
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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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self.running.throw(AlreadyJoinedError("Joining the same task multiple times is not allowed!"))
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def want_sleep(self, seconds):
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if seconds > 0: # If seconds <= 0 this function just acts as a checkpoint
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self.sequence += 1 # Make this specific sleeping task unique to avoid error when comparing identical deadlines
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heappush(self.paused, (self.clock() + seconds, self.sequence, self.running))
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else:
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self.to_run.append(self.running) # Reschedule the task that called sleep
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def want_cancel(self, task):
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self.to_run.extend(self.joined.pop(self.running, ()))
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self.to_run.append(self.running) # Reschedules the parent task
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try:
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task.throw(CancelledError())
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except Exception as e:
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task.result.exc = e
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async def connect_sock(self, sock: socket.socket, addr: tuple):
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try: # "Borrowed" from curio
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result = sock.connect(addr)
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return result
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except WantWrite:
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await _want_write(sock)
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err = sock.getsockopt(SOL_SOCKET, SO_ERROR)
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if err != 0:
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raise OSError(err, f'Connect call failed: {addr}')
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