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"""Event loop and event loop policy.""" __all__ = ['AbstractEventLoopPolicy', 'AbstractEventLoop', 'AbstractServer', 'Handle', 'TimerHandle', 'get_event_loop_policy', 'set_event_loop_policy', 'get_event_loop', 'set_event_loop', 'new_event_loop', 'get_child_watcher', 'set_child_watcher', '_set_running_loop', '_get_running_loop', ] import functools import inspect import os import reprlib import socket import subprocess import sys import threading import traceback from . import compat from . import constants def _get_function_source(func): if compat.PY34: func = inspect.unwrap(func) elif hasattr(func, '__wrapped__'): func = func.__wrapped__ if inspect.isfunction(func): code = func.__code__ return (code.co_filename, code.co_firstlineno) if isinstance(func, functools.partial): return _get_function_source(func.func) if compat.PY34 and isinstance(func, functools.partialmethod): return _get_function_source(func.func) return None def _format_args_and_kwargs(args, kwargs): """Format function arguments and keyword arguments. Special case for a single parameter: ('hello',) is formatted as ('hello'). """ # use reprlib to limit the length of the output items = [] if args: items.extend(reprlib.repr(arg) for arg in args) if kwargs: items.extend('{}={}'.format(k, reprlib.repr(v)) for k, v in kwargs.items()) return '(' + ', '.join(items) + ')' def _format_callback(func, args, kwargs, suffix=''): if isinstance(func, functools.partial): suffix = _format_args_and_kwargs(args, kwargs) + suffix return _format_callback(func.func, func.args, func.keywords, suffix) if hasattr(func, '__qualname__') and func.__qualname__: func_repr = func.__qualname__ elif hasattr(func, '__name__') and func.__name__: func_repr = func.__name__ else: func_repr = repr(func) func_repr += _format_args_and_kwargs(args, kwargs) if suffix: func_repr += suffix return func_repr def _format_callback_source(func, args): func_repr = _format_callback(func, args, None) source = _get_function_source(func) if source: func_repr += ' at %s:%s' % source return func_repr def extract_stack(f=None, limit=None): """Replacement for traceback.extract_stack() that only does the necessary work for asyncio debug mode. """ if f is None: f = sys._getframe().f_back if limit is None: # Limit the amount of work to a reasonable amount, as extract_stack() # can be called for each coroutine and future in debug mode. limit = constants.DEBUG_STACK_DEPTH stack = traceback.StackSummary.extract(traceback.walk_stack(f), limit=limit, lookup_lines=False) stack.reverse() return stack class Handle: """Object returned by callback registration methods.""" __slots__ = ('_callback', '_args', '_cancelled', '_loop', '_source_traceback', '_repr', '__weakref__') def __init__(self, callback, args, loop): self._loop = loop self._callback = callback self._args = args self._cancelled = False self._repr = None if self._loop.get_debug(): self._source_traceback = extract_stack(sys._getframe(1)) else: self._source_traceback = None def _repr_info(self): info = [self.__class__.__name__] if self._cancelled: info.append('cancelled') if self._callback is not None: info.append(_format_callback_source(self._callback, self._args)) if self._source_traceback: frame = self._source_traceback[-1] info.append('created at %s:%s' % (frame[0], frame[1])) return info def __repr__(self): if self._repr is not None: return self._repr info = self._repr_info() return '<%s>' % ' '.join(info) def cancel(self): if not self._cancelled: self._cancelled = True if self._loop.get_debug(): # Keep a representation in debug mode to keep callback and # parameters. For example, to log the warning # "Executing <Handle...> took 2.5 second" self._repr = repr(self) self._callback = None self._args = None def _run(self): try: self._callback(*self._args) except Exception as exc: cb = _format_callback_source(self._callback, self._args) msg = 'Exception in callback {}'.format(cb) context = { 'message': msg, 'exception': exc, 'handle': self, } if self._source_traceback: context['source_traceback'] = self._source_traceback self._loop.call_exception_handler(context) self = None # Needed to break cycles when an exception occurs. class TimerHandle(Handle): """Object returned by timed callback registration methods.""" __slots__ = ['_scheduled', '_when'] def __init__(self, when, callback, args, loop): assert when is not None super().__init__(callback, args, loop) if self._source_traceback: del self._source_traceback[-1] self._when = when self._scheduled = False def _repr_info(self): info = super()._repr_info() pos = 2 if self._cancelled else 1 info.insert(pos, 'when=%s' % self._when) return info def __hash__(self): return hash(self._when) def __lt__(self, other): return self._when < other._when def __le__(self, other): if self._when < other._when: return True return self.__eq__(other) def __gt__(self, other): return self._when > other._when def __ge__(self, other): if self._when > other._when: return True return self.__eq__(other) def __eq__(self, other): if isinstance(other, TimerHandle): return (self._when == other._when and self._callback == other._callback and self._args == other._args and self._cancelled == other._cancelled) return NotImplemented def __ne__(self, other): equal = self.__eq__(other) return NotImplemented if equal is NotImplemented else not equal def cancel(self): if not self._cancelled: self._loop._timer_handle_cancelled(self) super().cancel() class AbstractServer: """Abstract server returned by create_server().""" def close(self): """Stop serving. This leaves existing connections open.""" return NotImplemented def wait_closed(self): """Coroutine to wait until service is closed.""" return NotImplemented class AbstractEventLoop: """Abstract event loop.""" # Running and stopping the event loop. def run_forever(self): """Run the event loop until stop() is called.""" raise NotImplementedError def run_until_complete(self, future): """Run the event loop until a Future is done. Return the Future's result, or raise its exception. """ raise NotImplementedError def stop(self): """Stop the event loop as soon as reasonable. Exactly how soon that is may depend on the implementation, but no more I/O callbacks should be scheduled. """ raise NotImplementedError def is_running(self): """Return whether the event loop is currently running.""" raise NotImplementedError def is_closed(self): """Returns True if the event loop was closed.""" raise NotImplementedError def close(self): """Close the loop. The loop should not be running. This is idempotent and irreversible. No other methods should be called after this one. """ raise NotImplementedError def shutdown_asyncgens(self): """Shutdown all active asynchronous generators.""" raise NotImplementedError # Methods scheduling callbacks. All these return Handles. def _timer_handle_cancelled(self, handle): """Notification that a TimerHandle has been cancelled.""" raise NotImplementedError def call_soon(self, callback, *args): return self.call_later(0, callback, *args) def call_later(self, delay, callback, *args): raise NotImplementedError def call_at(self, when, callback, *args): raise NotImplementedError def time(self): raise NotImplementedError def create_future(self): raise NotImplementedError # Method scheduling a coroutine object: create a task. def create_task(self, coro): raise NotImplementedError # Methods for interacting with threads. def call_soon_threadsafe(self, callback, *args): raise NotImplementedError def run_in_executor(self, executor, func, *args): raise NotImplementedError def set_default_executor(self, executor): raise NotImplementedError # Network I/O methods returning Futures. def getaddrinfo(self, host, port, *, family=0, type=0, proto=0, flags=0): raise NotImplementedError def getnameinfo(self, sockaddr, flags=0): raise NotImplementedError def create_connection(self, protocol_factory, host=None, port=None, *, ssl=None, family=0, proto=0, flags=0, sock=None, local_addr=None, server_hostname=None): raise NotImplementedError def create_server(self, protocol_factory, host=None, port=None, *, family=socket.AF_UNSPEC, flags=socket.AI_PASSIVE, sock=None, backlog=100, ssl=None, reuse_address=None, reuse_port=None): """A coroutine which creates a TCP server bound to host and port. The return value is a Server object which can be used to stop the service. If host is an empty string or None all interfaces are assumed and a list of multiple sockets will be returned (most likely one for IPv4 and another one for IPv6). The host parameter can also be a sequence (e.g. list) of hosts to bind to. family can be set to either AF_INET or AF_INET6 to force the socket to use IPv4 or IPv6. If not set it will be determined from host (defaults to AF_UNSPEC). flags is a bitmask for getaddrinfo(). sock can optionally be specified in order to use a preexisting socket object. backlog is the maximum number of queued connections passed to listen() (defaults to 100). ssl can be set to an SSLContext to enable SSL over the accepted connections. reuse_address tells the kernel to reuse a local socket in TIME_WAIT state, without waiting for its natural timeout to expire. If not specified will automatically be set to True on UNIX. reuse_port tells the kernel to allow this endpoint to be bound to the same port as other existing endpoints are bound to, so long as they all set this flag when being created. This option is not supported on Windows. """ raise NotImplementedError def create_unix_connection(self, protocol_factory, path, *, ssl=None, sock=None, server_hostname=None): raise NotImplementedError def create_unix_server(self, protocol_factory, path, *, sock=None, backlog=100, ssl=None): """A coroutine which creates a UNIX Domain Socket server. The return value is a Server object, which can be used to stop the service. path is a str, representing a file systsem path to bind the server socket to. sock can optionally be specified in order to use a preexisting socket object. backlog is the maximum number of queued connections passed to listen() (defaults to 100). ssl can be set to an SSLContext to enable SSL over the accepted connections. """ raise NotImplementedError def create_datagram_endpoint(self, protocol_factory, local_addr=None, remote_addr=None, *, family=0, proto=0, flags=0, reuse_address=None, reuse_port=None, allow_broadcast=None, sock=None): """A coroutine which creates a datagram endpoint. This method will try to establish the endpoint in the background. When successful, the coroutine returns a (transport, protocol) pair. protocol_factory must be a callable returning a protocol instance. socket family AF_INET or socket.AF_INET6 depending on host (or family if specified), socket type SOCK_DGRAM. reuse_address tells the kernel to reuse a local socket in TIME_WAIT state, without waiting for its natural timeout to expire. If not specified it will automatically be set to True on UNIX. reuse_port tells the kernel to allow this endpoint to be bound to the same port as other existing endpoints are bound to, so long as they all set this flag when being created. This option is not supported on Windows and some UNIX's. If the :py:data:`~socket.SO_REUSEPORT` constant is not defined then this capability is unsupported. allow_broadcast tells the kernel to allow this endpoint to send messages to the broadcast address. sock can optionally be specified in order to use a preexisting socket object. """ raise NotImplementedError # Pipes and subprocesses. def connect_read_pipe(self, protocol_factory, pipe): """Register read pipe in event loop. Set the pipe to non-blocking mode. protocol_factory should instantiate object with Protocol interface. pipe is a file-like object. Return pair (transport, protocol), where transport supports the ReadTransport interface.""" # The reason to accept file-like object instead of just file descriptor # is: we need to own pipe and close it at transport finishing # Can got complicated errors if pass f.fileno(), # close fd in pipe transport then close f and vise versa. raise NotImplementedError def connect_write_pipe(self, protocol_factory, pipe): """Register write pipe in event loop. protocol_factory should instantiate object with BaseProtocol interface. Pipe is file-like object already switched to nonblocking. Return pair (transport, protocol), where transport support WriteTransport interface.""" # The reason to accept file-like object instead of just file descriptor # is: we need to own pipe and close it at transport finishing # Can got complicated errors if pass f.fileno(), # close fd in pipe transport then close f and vise versa. raise NotImplementedError def subprocess_shell(self, protocol_factory, cmd, *, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, **kwargs): raise NotImplementedError def subprocess_exec(self, protocol_factory, *args, stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, **kwargs): raise NotImplementedError # Ready-based callback registration methods. # The add_*() methods return None. # The remove_*() methods return True if something was removed, # False if there was nothing to delete. def add_reader(self, fd, callback, *args): raise NotImplementedError def remove_reader(self, fd): raise NotImplementedError def add_writer(self, fd, callback, *args): raise NotImplementedError def remove_writer(self, fd): raise NotImplementedError # Completion based I/O methods returning Futures. def sock_recv(self, sock, nbytes): raise NotImplementedError def sock_sendall(self, sock, data): raise NotImplementedError def sock_connect(self, sock, address): raise NotImplementedError def sock_accept(self, sock): raise NotImplementedError # Signal handling. def add_signal_handler(self, sig, callback, *args): raise NotImplementedError def remove_signal_handler(self, sig): raise NotImplementedError # Task factory. def set_task_factory(self, factory): raise NotImplementedError def get_task_factory(self): raise NotImplementedError # Error handlers. def get_exception_handler(self): raise NotImplementedError def set_exception_handler(self, handler): raise NotImplementedError def default_exception_handler(self, context): raise NotImplementedError def call_exception_handler(self, context): raise NotImplementedError # Debug flag management. def get_debug(self): raise NotImplementedError def set_debug(self, enabled): raise NotImplementedError class AbstractEventLoopPolicy: """Abstract policy for accessing the event loop.""" def get_event_loop(self): """Get the event loop for the current context. Returns an event loop object implementing the BaseEventLoop interface, or raises an exception in case no event loop has been set for the current context and the current policy does not specify to create one. It should never return None.""" raise NotImplementedError def set_event_loop(self, loop): """Set the event loop for the current context to loop.""" raise NotImplementedError def new_event_loop(self): """Create and return a new event loop object according to this policy's rules. If there's need to set this loop as the event loop for the current context, set_event_loop must be called explicitly.""" raise NotImplementedError # Child processes handling (Unix only). def get_child_watcher(self): "Get the watcher for child processes." raise NotImplementedError def set_child_watcher(self, watcher): """Set the watcher for child processes.""" raise NotImplementedError class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy): """Default policy implementation for accessing the event loop. In this policy, each thread has its own event loop. However, we only automatically create an event loop by default for the main thread; other threads by default have no event loop. Other policies may have different rules (e.g. a single global event loop, or automatically creating an event loop per thread, or using some other notion of context to which an event loop is associated). """ _loop_factory = None class _Local(threading.local): _loop = None _set_called = False def __init__(self): self._local = self._Local() def get_event_loop(self): """Get the event loop. This may be None or an instance of EventLoop. """ if (self._local._loop is None and not self._local._set_called and isinstance(threading.current_thread(), threading._MainThread)): self.set_event_loop(self.new_event_loop()) if self._local._loop is None: raise RuntimeError('There is no current event loop in thread %r.' % threading.current_thread().name) return self._local._loop def set_event_loop(self, loop): """Set the event loop.""" self._local._set_called = True assert loop is None or isinstance(loop, AbstractEventLoop) self._local._loop = loop def new_event_loop(self): """Create a new event loop. You must call set_event_loop() to make this the current event loop. """ return self._loop_factory() # Event loop policy. The policy itself is always global, even if the # policy's rules say that there is an event loop per thread (or other # notion of context). The default policy is installed by the first # call to get_event_loop_policy(). _event_loop_policy = None # Lock for protecting the on-the-fly creation of the event loop policy. _lock = threading.Lock() # A TLS for the running event loop, used by _get_running_loop. class _RunningLoop(threading.local): loop_pid = (None, None) _running_loop = _RunningLoop() def _get_running_loop(): """Return the running event loop or None. This is a low-level function intended to be used by event loops. This function is thread-specific. """ running_loop, pid = _running_loop.loop_pid if running_loop is not None and pid == os.getpid(): return running_loop def _set_running_loop(loop): """Set the running event loop. This is a low-level function intended to be used by event loops. This function is thread-specific. """ _running_loop.loop_pid = (loop, os.getpid()) def _init_event_loop_policy(): global _event_loop_policy with _lock: if _event_loop_policy is None: # pragma: no branch from . import DefaultEventLoopPolicy _event_loop_policy = DefaultEventLoopPolicy() def get_event_loop_policy(): """Get the current event loop policy.""" if _event_loop_policy is None: _init_event_loop_policy() return _event_loop_policy def set_event_loop_policy(policy): """Set the current event loop policy. If policy is None, the default policy is restored.""" global _event_loop_policy assert policy is None or isinstance(policy, AbstractEventLoopPolicy) _event_loop_policy = policy def get_event_loop(): """Return an asyncio event loop. When called from a coroutine or a callback (e.g. scheduled with call_soon or similar API), this function will always return the running event loop. If there is no running event loop set, the function will return the result of `get_event_loop_policy().get_event_loop()` call. """ current_loop = _get_running_loop() if current_loop is not None: return current_loop return get_event_loop_policy().get_event_loop() def set_event_loop(loop): """Equivalent to calling get_event_loop_policy().set_event_loop(loop).""" get_event_loop_policy().set_event_loop(loop) def new_event_loop(): """Equivalent to calling get_event_loop_policy().new_event_loop().""" return get_event_loop_policy().new_event_loop() def get_child_watcher(): """Equivalent to calling get_event_loop_policy().get_child_watcher().""" return get_event_loop_policy().get_child_watcher() def set_child_watcher(watcher): """Equivalent to calling get_event_loop_policy().set_child_watcher(watcher).""" return get_event_loop_policy().set_child_watcher(watcher)