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Diffstat (limited to 'external_libs/python/zmq/eventloop/minitornado')
12 files changed, 1695 insertions, 0 deletions
diff --git a/external_libs/python/zmq/eventloop/minitornado/__init__.py b/external_libs/python/zmq/eventloop/minitornado/__init__.py new file mode 100644 index 00000000..e69de29b --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/__init__.py diff --git a/external_libs/python/zmq/eventloop/minitornado/concurrent.py b/external_libs/python/zmq/eventloop/minitornado/concurrent.py new file mode 100644 index 00000000..519b23d5 --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/concurrent.py @@ -0,0 +1,11 @@ +"""pyzmq does not ship tornado's futures, +this just raises informative NotImplementedErrors to avoid having to change too much code. +""" + +class NotImplementedFuture(object): + def __init__(self, *args, **kwargs): + raise NotImplementedError("pyzmq does not ship tornado's Futures, " + "install tornado >= 3.0 for future support." + ) + +Future = TracebackFuture = NotImplementedFuture diff --git a/external_libs/python/zmq/eventloop/minitornado/ioloop.py b/external_libs/python/zmq/eventloop/minitornado/ioloop.py new file mode 100644 index 00000000..710a3ecb --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/ioloop.py @@ -0,0 +1,829 @@ +#!/usr/bin/env python +# +# Copyright 2009 Facebook +# +# 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. + +"""An I/O event loop for non-blocking sockets. + +Typical applications will use a single `IOLoop` object, in the +`IOLoop.instance` singleton. The `IOLoop.start` method should usually +be called at the end of the ``main()`` function. Atypical applications may +use more than one `IOLoop`, such as one `IOLoop` per thread, or per `unittest` +case. + +In addition to I/O events, the `IOLoop` can also schedule time-based events. +`IOLoop.add_timeout` is a non-blocking alternative to `time.sleep`. +""" + +from __future__ import absolute_import, division, print_function, with_statement + +import datetime +import errno +import functools +import heapq +import logging +import numbers +import os +import select +import sys +import threading +import time +import traceback + +from .concurrent import Future, TracebackFuture +from .log import app_log, gen_log +from . import stack_context +from .util import Configurable + +try: + import signal +except ImportError: + signal = None + +try: + import thread # py2 +except ImportError: + import _thread as thread # py3 + +from .platform.auto import set_close_exec, Waker + + +class TimeoutError(Exception): + pass + + +class IOLoop(Configurable): + """A level-triggered I/O loop. + + We use ``epoll`` (Linux) or ``kqueue`` (BSD and Mac OS X) if they + are available, or else we fall back on select(). If you are + implementing a system that needs to handle thousands of + simultaneous connections, you should use a system that supports + either ``epoll`` or ``kqueue``. + + Example usage for a simple TCP server:: + + import errno + import functools + import ioloop + import socket + + def connection_ready(sock, fd, events): + while True: + try: + connection, address = sock.accept() + except socket.error, e: + if e.args[0] not in (errno.EWOULDBLOCK, errno.EAGAIN): + raise + return + connection.setblocking(0) + handle_connection(connection, address) + + sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) + sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) + sock.setblocking(0) + sock.bind(("", port)) + sock.listen(128) + + io_loop = ioloop.IOLoop.instance() + callback = functools.partial(connection_ready, sock) + io_loop.add_handler(sock.fileno(), callback, io_loop.READ) + io_loop.start() + + """ + # Constants from the epoll module + _EPOLLIN = 0x001 + _EPOLLPRI = 0x002 + _EPOLLOUT = 0x004 + _EPOLLERR = 0x008 + _EPOLLHUP = 0x010 + _EPOLLRDHUP = 0x2000 + _EPOLLONESHOT = (1 << 30) + _EPOLLET = (1 << 31) + + # Our events map exactly to the epoll events + NONE = 0 + READ = _EPOLLIN + WRITE = _EPOLLOUT + ERROR = _EPOLLERR | _EPOLLHUP + + # Global lock for creating global IOLoop instance + _instance_lock = threading.Lock() + + _current = threading.local() + + @staticmethod + def instance(): + """Returns a global `IOLoop` instance. + + Most applications have a single, global `IOLoop` running on the + main thread. Use this method to get this instance from + another thread. To get the current thread's `IOLoop`, use `current()`. + """ + if not hasattr(IOLoop, "_instance"): + with IOLoop._instance_lock: + if not hasattr(IOLoop, "_instance"): + # New instance after double check + IOLoop._instance = IOLoop() + return IOLoop._instance + + @staticmethod + def initialized(): + """Returns true if the singleton instance has been created.""" + return hasattr(IOLoop, "_instance") + + def install(self): + """Installs this `IOLoop` object as the singleton instance. + + This is normally not necessary as `instance()` will create + an `IOLoop` on demand, but you may want to call `install` to use + a custom subclass of `IOLoop`. + """ + assert not IOLoop.initialized() + IOLoop._instance = self + + @staticmethod + def current(): + """Returns the current thread's `IOLoop`. + + If an `IOLoop` is currently running or has been marked as current + by `make_current`, returns that instance. Otherwise returns + `IOLoop.instance()`, i.e. the main thread's `IOLoop`. + + A common pattern for classes that depend on ``IOLoops`` is to use + a default argument to enable programs with multiple ``IOLoops`` + but not require the argument for simpler applications:: + + class MyClass(object): + def __init__(self, io_loop=None): + self.io_loop = io_loop or IOLoop.current() + + In general you should use `IOLoop.current` as the default when + constructing an asynchronous object, and use `IOLoop.instance` + when you mean to communicate to the main thread from a different + one. + """ + current = getattr(IOLoop._current, "instance", None) + if current is None: + return IOLoop.instance() + return current + + def make_current(self): + """Makes this the `IOLoop` for the current thread. + + An `IOLoop` automatically becomes current for its thread + when it is started, but it is sometimes useful to call + `make_current` explictly before starting the `IOLoop`, + so that code run at startup time can find the right + instance. + """ + IOLoop._current.instance = self + + @staticmethod + def clear_current(): + IOLoop._current.instance = None + + @classmethod + def configurable_base(cls): + return IOLoop + + @classmethod + def configurable_default(cls): + # this is the only patch to IOLoop: + from zmq.eventloop.ioloop import ZMQIOLoop + return ZMQIOLoop + # the remainder of this method is unused, + # but left for preservation reasons + if hasattr(select, "epoll"): + from tornado.platform.epoll import EPollIOLoop + return EPollIOLoop + if hasattr(select, "kqueue"): + # Python 2.6+ on BSD or Mac + from tornado.platform.kqueue import KQueueIOLoop + return KQueueIOLoop + from tornado.platform.select import SelectIOLoop + return SelectIOLoop + + def initialize(self): + pass + + def close(self, all_fds=False): + """Closes the `IOLoop`, freeing any resources used. + + If ``all_fds`` is true, all file descriptors registered on the + IOLoop will be closed (not just the ones created by the + `IOLoop` itself). + + Many applications will only use a single `IOLoop` that runs for the + entire lifetime of the process. In that case closing the `IOLoop` + is not necessary since everything will be cleaned up when the + process exits. `IOLoop.close` is provided mainly for scenarios + such as unit tests, which create and destroy a large number of + ``IOLoops``. + + An `IOLoop` must be completely stopped before it can be closed. This + means that `IOLoop.stop()` must be called *and* `IOLoop.start()` must + be allowed to return before attempting to call `IOLoop.close()`. + Therefore the call to `close` will usually appear just after + the call to `start` rather than near the call to `stop`. + + .. versionchanged:: 3.1 + If the `IOLoop` implementation supports non-integer objects + for "file descriptors", those objects will have their + ``close`` method when ``all_fds`` is true. + """ + raise NotImplementedError() + + def add_handler(self, fd, handler, events): + """Registers the given handler to receive the given events for fd. + + The ``events`` argument is a bitwise or of the constants + ``IOLoop.READ``, ``IOLoop.WRITE``, and ``IOLoop.ERROR``. + + When an event occurs, ``handler(fd, events)`` will be run. + """ + raise NotImplementedError() + + def update_handler(self, fd, events): + """Changes the events we listen for fd.""" + raise NotImplementedError() + + def remove_handler(self, fd): + """Stop listening for events on fd.""" + raise NotImplementedError() + + def set_blocking_signal_threshold(self, seconds, action): + """Sends a signal if the `IOLoop` is blocked for more than + ``s`` seconds. + + Pass ``seconds=None`` to disable. Requires Python 2.6 on a unixy + platform. + + The action parameter is a Python signal handler. Read the + documentation for the `signal` module for more information. + If ``action`` is None, the process will be killed if it is + blocked for too long. + """ + raise NotImplementedError() + + def set_blocking_log_threshold(self, seconds): + """Logs a stack trace if the `IOLoop` is blocked for more than + ``s`` seconds. + + Equivalent to ``set_blocking_signal_threshold(seconds, + self.log_stack)`` + """ + self.set_blocking_signal_threshold(seconds, self.log_stack) + + def log_stack(self, signal, frame): + """Signal handler to log the stack trace of the current thread. + + For use with `set_blocking_signal_threshold`. + """ + gen_log.warning('IOLoop blocked for %f seconds in\n%s', + self._blocking_signal_threshold, + ''.join(traceback.format_stack(frame))) + + def start(self): + """Starts the I/O loop. + + The loop will run until one of the callbacks calls `stop()`, which + will make the loop stop after the current event iteration completes. + """ + raise NotImplementedError() + + def stop(self): + """Stop the I/O loop. + + If the event loop is not currently running, the next call to `start()` + will return immediately. + + To use asynchronous methods from otherwise-synchronous code (such as + unit tests), you can start and stop the event loop like this:: + + ioloop = IOLoop() + async_method(ioloop=ioloop, callback=ioloop.stop) + ioloop.start() + + ``ioloop.start()`` will return after ``async_method`` has run + its callback, whether that callback was invoked before or + after ``ioloop.start``. + + Note that even after `stop` has been called, the `IOLoop` is not + completely stopped until `IOLoop.start` has also returned. + Some work that was scheduled before the call to `stop` may still + be run before the `IOLoop` shuts down. + """ + raise NotImplementedError() + + def run_sync(self, func, timeout=None): + """Starts the `IOLoop`, runs the given function, and stops the loop. + + If the function returns a `.Future`, the `IOLoop` will run + until the future is resolved. If it raises an exception, the + `IOLoop` will stop and the exception will be re-raised to the + caller. + + The keyword-only argument ``timeout`` may be used to set + a maximum duration for the function. If the timeout expires, + a `TimeoutError` is raised. + + This method is useful in conjunction with `tornado.gen.coroutine` + to allow asynchronous calls in a ``main()`` function:: + + @gen.coroutine + def main(): + # do stuff... + + if __name__ == '__main__': + IOLoop.instance().run_sync(main) + """ + future_cell = [None] + + def run(): + try: + result = func() + except Exception: + future_cell[0] = TracebackFuture() + future_cell[0].set_exc_info(sys.exc_info()) + else: + if isinstance(result, Future): + future_cell[0] = result + else: + future_cell[0] = Future() + future_cell[0].set_result(result) + self.add_future(future_cell[0], lambda future: self.stop()) + self.add_callback(run) + if timeout is not None: + timeout_handle = self.add_timeout(self.time() + timeout, self.stop) + self.start() + if timeout is not None: + self.remove_timeout(timeout_handle) + if not future_cell[0].done(): + raise TimeoutError('Operation timed out after %s seconds' % timeout) + return future_cell[0].result() + + def time(self): + """Returns the current time according to the `IOLoop`'s clock. + + The return value is a floating-point number relative to an + unspecified time in the past. + + By default, the `IOLoop`'s time function is `time.time`. However, + it may be configured to use e.g. `time.monotonic` instead. + Calls to `add_timeout` that pass a number instead of a + `datetime.timedelta` should use this function to compute the + appropriate time, so they can work no matter what time function + is chosen. + """ + return time.time() + + def add_timeout(self, deadline, callback): + """Runs the ``callback`` at the time ``deadline`` from the I/O loop. + + Returns an opaque handle that may be passed to + `remove_timeout` to cancel. + + ``deadline`` may be a number denoting a time (on the same + scale as `IOLoop.time`, normally `time.time`), or a + `datetime.timedelta` object for a deadline relative to the + current time. + + Note that it is not safe to call `add_timeout` from other threads. + Instead, you must use `add_callback` to transfer control to the + `IOLoop`'s thread, and then call `add_timeout` from there. + """ + raise NotImplementedError() + + def remove_timeout(self, timeout): + """Cancels a pending timeout. + + The argument is a handle as returned by `add_timeout`. It is + safe to call `remove_timeout` even if the callback has already + been run. + """ + raise NotImplementedError() + + def add_callback(self, callback, *args, **kwargs): + """Calls the given callback on the next I/O loop iteration. + + It is safe to call this method from any thread at any time, + except from a signal handler. Note that this is the **only** + method in `IOLoop` that makes this thread-safety guarantee; all + other interaction with the `IOLoop` must be done from that + `IOLoop`'s thread. `add_callback()` may be used to transfer + control from other threads to the `IOLoop`'s thread. + + To add a callback from a signal handler, see + `add_callback_from_signal`. + """ + raise NotImplementedError() + + def add_callback_from_signal(self, callback, *args, **kwargs): + """Calls the given callback on the next I/O loop iteration. + + Safe for use from a Python signal handler; should not be used + otherwise. + + Callbacks added with this method will be run without any + `.stack_context`, to avoid picking up the context of the function + that was interrupted by the signal. + """ + raise NotImplementedError() + + def add_future(self, future, callback): + """Schedules a callback on the ``IOLoop`` when the given + `.Future` is finished. + + The callback is invoked with one argument, the + `.Future`. + """ + assert isinstance(future, Future) + callback = stack_context.wrap(callback) + future.add_done_callback( + lambda future: self.add_callback(callback, future)) + + def _run_callback(self, callback): + """Runs a callback with error handling. + + For use in subclasses. + """ + try: + callback() + except Exception: + self.handle_callback_exception(callback) + + def handle_callback_exception(self, callback): + """This method is called whenever a callback run by the `IOLoop` + throws an exception. + + By default simply logs the exception as an error. Subclasses + may override this method to customize reporting of exceptions. + + The exception itself is not passed explicitly, but is available + in `sys.exc_info`. + """ + app_log.error("Exception in callback %r", callback, exc_info=True) + + +class PollIOLoop(IOLoop): + """Base class for IOLoops built around a select-like function. + + For concrete implementations, see `tornado.platform.epoll.EPollIOLoop` + (Linux), `tornado.platform.kqueue.KQueueIOLoop` (BSD and Mac), or + `tornado.platform.select.SelectIOLoop` (all platforms). + """ + def initialize(self, impl, time_func=None): + super(PollIOLoop, self).initialize() + self._impl = impl + if hasattr(self._impl, 'fileno'): + set_close_exec(self._impl.fileno()) + self.time_func = time_func or time.time + self._handlers = {} + self._events = {} + self._callbacks = [] + self._callback_lock = threading.Lock() + self._timeouts = [] + self._cancellations = 0 + self._running = False + self._stopped = False + self._closing = False + self._thread_ident = None + self._blocking_signal_threshold = None + + # Create a pipe that we send bogus data to when we want to wake + # the I/O loop when it is idle + self._waker = Waker() + self.add_handler(self._waker.fileno(), + lambda fd, events: self._waker.consume(), + self.READ) + + def close(self, all_fds=False): + with self._callback_lock: + self._closing = True + self.remove_handler(self._waker.fileno()) + if all_fds: + for fd in self._handlers.keys(): + try: + close_method = getattr(fd, 'close', None) + if close_method is not None: + close_method() + else: + os.close(fd) + except Exception: + gen_log.debug("error closing fd %s", fd, exc_info=True) + self._waker.close() + self._impl.close() + + def add_handler(self, fd, handler, events): + self._handlers[fd] = stack_context.wrap(handler) + self._impl.register(fd, events | self.ERROR) + + def update_handler(self, fd, events): + self._impl.modify(fd, events | self.ERROR) + + def remove_handler(self, fd): + self._handlers.pop(fd, None) + self._events.pop(fd, None) + try: + self._impl.unregister(fd) + except Exception: + gen_log.debug("Error deleting fd from IOLoop", exc_info=True) + + def set_blocking_signal_threshold(self, seconds, action): + if not hasattr(signal, "setitimer"): + gen_log.error("set_blocking_signal_threshold requires a signal module " + "with the setitimer method") + return + self._blocking_signal_threshold = seconds + if seconds is not None: + signal.signal(signal.SIGALRM, + action if action is not None else signal.SIG_DFL) + + def start(self): + if not logging.getLogger().handlers: + # The IOLoop catches and logs exceptions, so it's + # important that log output be visible. However, python's + # default behavior for non-root loggers (prior to python + # 3.2) is to print an unhelpful "no handlers could be + # found" message rather than the actual log entry, so we + # must explicitly configure logging if we've made it this + # far without anything. + logging.basicConfig() + if self._stopped: + self._stopped = False + return + old_current = getattr(IOLoop._current, "instance", None) + IOLoop._current.instance = self + self._thread_ident = thread.get_ident() + self._running = True + + # signal.set_wakeup_fd closes a race condition in event loops: + # a signal may arrive at the beginning of select/poll/etc + # before it goes into its interruptible sleep, so the signal + # will be consumed without waking the select. The solution is + # for the (C, synchronous) signal handler to write to a pipe, + # which will then be seen by select. + # + # In python's signal handling semantics, this only matters on the + # main thread (fortunately, set_wakeup_fd only works on the main + # thread and will raise a ValueError otherwise). + # + # If someone has already set a wakeup fd, we don't want to + # disturb it. This is an issue for twisted, which does its + # SIGCHILD processing in response to its own wakeup fd being + # written to. As long as the wakeup fd is registered on the IOLoop, + # the loop will still wake up and everything should work. + old_wakeup_fd = None + if hasattr(signal, 'set_wakeup_fd') and os.name == 'posix': + # requires python 2.6+, unix. set_wakeup_fd exists but crashes + # the python process on windows. + try: + old_wakeup_fd = signal.set_wakeup_fd(self._waker.write_fileno()) + if old_wakeup_fd != -1: + # Already set, restore previous value. This is a little racy, + # but there's no clean get_wakeup_fd and in real use the + # IOLoop is just started once at the beginning. + signal.set_wakeup_fd(old_wakeup_fd) + old_wakeup_fd = None + except ValueError: # non-main thread + pass + + while True: + poll_timeout = 3600.0 + + # Prevent IO event starvation by delaying new callbacks + # to the next iteration of the event loop. + with self._callback_lock: + callbacks = self._callbacks + self._callbacks = [] + for callback in callbacks: + self._run_callback(callback) + + if self._timeouts: + now = self.time() + while self._timeouts: + if self._timeouts[0].callback is None: + # the timeout was cancelled + heapq.heappop(self._timeouts) + self._cancellations -= 1 + elif self._timeouts[0].deadline <= now: + timeout = heapq.heappop(self._timeouts) + self._run_callback(timeout.callback) + else: + seconds = self._timeouts[0].deadline - now + poll_timeout = min(seconds, poll_timeout) + break + if (self._cancellations > 512 + and self._cancellations > (len(self._timeouts) >> 1)): + # Clean up the timeout queue when it gets large and it's + # more than half cancellations. + self._cancellations = 0 + self._timeouts = [x for x in self._timeouts + if x.callback is not None] + heapq.heapify(self._timeouts) + + if self._callbacks: + # If any callbacks or timeouts called add_callback, + # we don't want to wait in poll() before we run them. + poll_timeout = 0.0 + + if not self._running: + break + + if self._blocking_signal_threshold is not None: + # clear alarm so it doesn't fire while poll is waiting for + # events. + signal.setitimer(signal.ITIMER_REAL, 0, 0) + + try: + event_pairs = self._impl.poll(poll_timeout) + except Exception as e: + # Depending on python version and IOLoop implementation, + # different exception types may be thrown and there are + # two ways EINTR might be signaled: + # * e.errno == errno.EINTR + # * e.args is like (errno.EINTR, 'Interrupted system call') + if (getattr(e, 'errno', None) == errno.EINTR or + (isinstance(getattr(e, 'args', None), tuple) and + len(e.args) == 2 and e.args[0] == errno.EINTR)): + continue + else: + raise + + if self._blocking_signal_threshold is not None: + signal.setitimer(signal.ITIMER_REAL, + self._blocking_signal_threshold, 0) + + # Pop one fd at a time from the set of pending fds and run + # its handler. Since that handler may perform actions on + # other file descriptors, there may be reentrant calls to + # this IOLoop that update self._events + self._events.update(event_pairs) + while self._events: + fd, events = self._events.popitem() + try: + self._handlers[fd](fd, events) + except (OSError, IOError) as e: + if e.args[0] == errno.EPIPE: + # Happens when the client closes the connection + pass + else: + app_log.error("Exception in I/O handler for fd %s", + fd, exc_info=True) + except Exception: + app_log.error("Exception in I/O handler for fd %s", + fd, exc_info=True) + # reset the stopped flag so another start/stop pair can be issued + self._stopped = False + if self._blocking_signal_threshold is not None: + signal.setitimer(signal.ITIMER_REAL, 0, 0) + IOLoop._current.instance = old_current + if old_wakeup_fd is not None: + signal.set_wakeup_fd(old_wakeup_fd) + + def stop(self): + self._running = False + self._stopped = True + self._waker.wake() + + def time(self): + return self.time_func() + + def add_timeout(self, deadline, callback): + timeout = _Timeout(deadline, stack_context.wrap(callback), self) + heapq.heappush(self._timeouts, timeout) + return timeout + + def remove_timeout(self, timeout): + # Removing from a heap is complicated, so just leave the defunct + # timeout object in the queue (see discussion in + # http://docs.python.org/library/heapq.html). + # If this turns out to be a problem, we could add a garbage + # collection pass whenever there are too many dead timeouts. + timeout.callback = None + self._cancellations += 1 + + def add_callback(self, callback, *args, **kwargs): + with self._callback_lock: + if self._closing: + raise RuntimeError("IOLoop is closing") + list_empty = not self._callbacks + self._callbacks.append(functools.partial( + stack_context.wrap(callback), *args, **kwargs)) + if list_empty and thread.get_ident() != self._thread_ident: + # If we're in the IOLoop's thread, we know it's not currently + # polling. If we're not, and we added the first callback to an + # empty list, we may need to wake it up (it may wake up on its + # own, but an occasional extra wake is harmless). Waking + # up a polling IOLoop is relatively expensive, so we try to + # avoid it when we can. + self._waker.wake() + + def add_callback_from_signal(self, callback, *args, **kwargs): + with stack_context.NullContext(): + if thread.get_ident() != self._thread_ident: + # if the signal is handled on another thread, we can add + # it normally (modulo the NullContext) + self.add_callback(callback, *args, **kwargs) + else: + # If we're on the IOLoop's thread, we cannot use + # the regular add_callback because it may deadlock on + # _callback_lock. Blindly insert into self._callbacks. + # This is safe because the GIL makes list.append atomic. + # One subtlety is that if the signal interrupted the + # _callback_lock block in IOLoop.start, we may modify + # either the old or new version of self._callbacks, + # but either way will work. + self._callbacks.append(functools.partial( + stack_context.wrap(callback), *args, **kwargs)) + + +class _Timeout(object): + """An IOLoop timeout, a UNIX timestamp and a callback""" + + # Reduce memory overhead when there are lots of pending callbacks + __slots__ = ['deadline', 'callback'] + + def __init__(self, deadline, callback, io_loop): + if isinstance(deadline, numbers.Real): + self.deadline = deadline + elif isinstance(deadline, datetime.timedelta): + self.deadline = io_loop.time() + _Timeout.timedelta_to_seconds(deadline) + else: + raise TypeError("Unsupported deadline %r" % deadline) + self.callback = callback + + @staticmethod + def timedelta_to_seconds(td): + """Equivalent to td.total_seconds() (introduced in python 2.7).""" + return (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10 ** 6) / float(10 ** 6) + + # Comparison methods to sort by deadline, with object id as a tiebreaker + # to guarantee a consistent ordering. The heapq module uses __le__ + # in python2.5, and __lt__ in 2.6+ (sort() and most other comparisons + # use __lt__). + def __lt__(self, other): + return ((self.deadline, id(self)) < + (other.deadline, id(other))) + + def __le__(self, other): + return ((self.deadline, id(self)) <= + (other.deadline, id(other))) + + +class PeriodicCallback(object): + """Schedules the given callback to be called periodically. + + The callback is called every ``callback_time`` milliseconds. + + `start` must be called after the `PeriodicCallback` is created. + """ + def __init__(self, callback, callback_time, io_loop=None): + self.callback = callback + if callback_time <= 0: + raise ValueError("Periodic callback must have a positive callback_time") + self.callback_time = callback_time + self.io_loop = io_loop or IOLoop.current() + self._running = False + self._timeout = None + + def start(self): + """Starts the timer.""" + self._running = True + self._next_timeout = self.io_loop.time() + self._schedule_next() + + def stop(self): + """Stops the timer.""" + self._running = False + if self._timeout is not None: + self.io_loop.remove_timeout(self._timeout) + self._timeout = None + + def _run(self): + if not self._running: + return + try: + self.callback() + except Exception: + app_log.error("Error in periodic callback", exc_info=True) + self._schedule_next() + + def _schedule_next(self): + if self._running: + current_time = self.io_loop.time() + while self._next_timeout <= current_time: + self._next_timeout += self.callback_time / 1000.0 + self._timeout = self.io_loop.add_timeout(self._next_timeout, self._run) diff --git a/external_libs/python/zmq/eventloop/minitornado/log.py b/external_libs/python/zmq/eventloop/minitornado/log.py new file mode 100644 index 00000000..49051e89 --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/log.py @@ -0,0 +1,6 @@ +"""minimal subset of tornado.log for zmq.eventloop.minitornado""" + +import logging + +app_log = logging.getLogger("tornado.application") +gen_log = logging.getLogger("tornado.general") diff --git a/external_libs/python/zmq/eventloop/minitornado/platform/__init__.py b/external_libs/python/zmq/eventloop/minitornado/platform/__init__.py new file mode 100644 index 00000000..e69de29b --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/platform/__init__.py diff --git a/external_libs/python/zmq/eventloop/minitornado/platform/auto.py b/external_libs/python/zmq/eventloop/minitornado/platform/auto.py new file mode 100644 index 00000000..b40ccd94 --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/platform/auto.py @@ -0,0 +1,45 @@ +#!/usr/bin/env python +# +# Copyright 2011 Facebook +# +# 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. + +"""Implementation of platform-specific functionality. + +For each function or class described in `tornado.platform.interface`, +the appropriate platform-specific implementation exists in this module. +Most code that needs access to this functionality should do e.g.:: + + from tornado.platform.auto import set_close_exec +""" + +from __future__ import absolute_import, division, print_function, with_statement + +import os + +if os.name == 'nt': + from .common import Waker + from .windows import set_close_exec +else: + from .posix import set_close_exec, Waker + +try: + # monotime monkey-patches the time module to have a monotonic function + # in versions of python before 3.3. + import monotime +except ImportError: + pass +try: + from time import monotonic as monotonic_time +except ImportError: + monotonic_time = None diff --git a/external_libs/python/zmq/eventloop/minitornado/platform/common.py b/external_libs/python/zmq/eventloop/minitornado/platform/common.py new file mode 100644 index 00000000..2d75dc1e --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/platform/common.py @@ -0,0 +1,91 @@ +"""Lowest-common-denominator implementations of platform functionality.""" +from __future__ import absolute_import, division, print_function, with_statement + +import errno +import socket + +from . import interface + + +class Waker(interface.Waker): + """Create an OS independent asynchronous pipe. + + For use on platforms that don't have os.pipe() (or where pipes cannot + be passed to select()), but do have sockets. This includes Windows + and Jython. + """ + def __init__(self): + # Based on Zope async.py: http://svn.zope.org/zc.ngi/trunk/src/zc/ngi/async.py + + self.writer = socket.socket() + # Disable buffering -- pulling the trigger sends 1 byte, + # and we want that sent immediately, to wake up ASAP. + self.writer.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1) + + count = 0 + while 1: + count += 1 + # Bind to a local port; for efficiency, let the OS pick + # a free port for us. + # Unfortunately, stress tests showed that we may not + # be able to connect to that port ("Address already in + # use") despite that the OS picked it. This appears + # to be a race bug in the Windows socket implementation. + # So we loop until a connect() succeeds (almost always + # on the first try). See the long thread at + # http://mail.zope.org/pipermail/zope/2005-July/160433.html + # for hideous details. + a = socket.socket() + a.bind(("127.0.0.1", 0)) + a.listen(1) + connect_address = a.getsockname() # assigned (host, port) pair + try: + self.writer.connect(connect_address) + break # success + except socket.error as detail: + if (not hasattr(errno, 'WSAEADDRINUSE') or + detail[0] != errno.WSAEADDRINUSE): + # "Address already in use" is the only error + # I've seen on two WinXP Pro SP2 boxes, under + # Pythons 2.3.5 and 2.4.1. + raise + # (10048, 'Address already in use') + # assert count <= 2 # never triggered in Tim's tests + if count >= 10: # I've never seen it go above 2 + a.close() + self.writer.close() + raise socket.error("Cannot bind trigger!") + # Close `a` and try again. Note: I originally put a short + # sleep() here, but it didn't appear to help or hurt. + a.close() + + self.reader, addr = a.accept() + self.reader.setblocking(0) + self.writer.setblocking(0) + a.close() + self.reader_fd = self.reader.fileno() + + def fileno(self): + return self.reader.fileno() + + def write_fileno(self): + return self.writer.fileno() + + def wake(self): + try: + self.writer.send(b"x") + except (IOError, socket.error): + pass + + def consume(self): + try: + while True: + result = self.reader.recv(1024) + if not result: + break + except (IOError, socket.error): + pass + + def close(self): + self.reader.close() + self.writer.close() diff --git a/external_libs/python/zmq/eventloop/minitornado/platform/interface.py b/external_libs/python/zmq/eventloop/minitornado/platform/interface.py new file mode 100644 index 00000000..07da6bab --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/platform/interface.py @@ -0,0 +1,63 @@ +#!/usr/bin/env python +# +# Copyright 2011 Facebook +# +# 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. + +"""Interfaces for platform-specific functionality. + +This module exists primarily for documentation purposes and as base classes +for other tornado.platform modules. Most code should import the appropriate +implementation from `tornado.platform.auto`. +""" + +from __future__ import absolute_import, division, print_function, with_statement + + +def set_close_exec(fd): + """Sets the close-on-exec bit (``FD_CLOEXEC``)for a file descriptor.""" + raise NotImplementedError() + + +class Waker(object): + """A socket-like object that can wake another thread from ``select()``. + + The `~tornado.ioloop.IOLoop` will add the Waker's `fileno()` to + its ``select`` (or ``epoll`` or ``kqueue``) calls. When another + thread wants to wake up the loop, it calls `wake`. Once it has woken + up, it will call `consume` to do any necessary per-wake cleanup. When + the ``IOLoop`` is closed, it closes its waker too. + """ + def fileno(self): + """Returns the read file descriptor for this waker. + + Must be suitable for use with ``select()`` or equivalent on the + local platform. + """ + raise NotImplementedError() + + def write_fileno(self): + """Returns the write file descriptor for this waker.""" + raise NotImplementedError() + + def wake(self): + """Triggers activity on the waker's file descriptor.""" + raise NotImplementedError() + + def consume(self): + """Called after the listen has woken up to do any necessary cleanup.""" + raise NotImplementedError() + + def close(self): + """Closes the waker's file descriptor(s).""" + raise NotImplementedError() diff --git a/external_libs/python/zmq/eventloop/minitornado/platform/posix.py b/external_libs/python/zmq/eventloop/minitornado/platform/posix.py new file mode 100644 index 00000000..ccffbb66 --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/platform/posix.py @@ -0,0 +1,70 @@ +#!/usr/bin/env python +# +# Copyright 2011 Facebook +# +# 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. + +"""Posix implementations of platform-specific functionality.""" + +from __future__ import absolute_import, division, print_function, with_statement + +import fcntl +import os + +from . import interface + + +def set_close_exec(fd): + flags = fcntl.fcntl(fd, fcntl.F_GETFD) + fcntl.fcntl(fd, fcntl.F_SETFD, flags | fcntl.FD_CLOEXEC) + + +def _set_nonblocking(fd): + flags = fcntl.fcntl(fd, fcntl.F_GETFL) + fcntl.fcntl(fd, fcntl.F_SETFL, flags | os.O_NONBLOCK) + + +class Waker(interface.Waker): + def __init__(self): + r, w = os.pipe() + _set_nonblocking(r) + _set_nonblocking(w) + set_close_exec(r) + set_close_exec(w) + self.reader = os.fdopen(r, "rb", 0) + self.writer = os.fdopen(w, "wb", 0) + + def fileno(self): + return self.reader.fileno() + + def write_fileno(self): + return self.writer.fileno() + + def wake(self): + try: + self.writer.write(b"x") + except IOError: + pass + + def consume(self): + try: + while True: + result = self.reader.read() + if not result: + break + except IOError: + pass + + def close(self): + self.reader.close() + self.writer.close() diff --git a/external_libs/python/zmq/eventloop/minitornado/platform/windows.py b/external_libs/python/zmq/eventloop/minitornado/platform/windows.py new file mode 100644 index 00000000..817bdca1 --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/platform/windows.py @@ -0,0 +1,20 @@ +# NOTE: win32 support is currently experimental, and not recommended +# for production use. + + +from __future__ import absolute_import, division, print_function, with_statement +import ctypes +import ctypes.wintypes + +# See: http://msdn.microsoft.com/en-us/library/ms724935(VS.85).aspx +SetHandleInformation = ctypes.windll.kernel32.SetHandleInformation +SetHandleInformation.argtypes = (ctypes.wintypes.HANDLE, ctypes.wintypes.DWORD, ctypes.wintypes.DWORD) +SetHandleInformation.restype = ctypes.wintypes.BOOL + +HANDLE_FLAG_INHERIT = 0x00000001 + + +def set_close_exec(fd): + success = SetHandleInformation(fd, HANDLE_FLAG_INHERIT, 0) + if not success: + raise ctypes.GetLastError() diff --git a/external_libs/python/zmq/eventloop/minitornado/stack_context.py b/external_libs/python/zmq/eventloop/minitornado/stack_context.py new file mode 100644 index 00000000..226d8042 --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/stack_context.py @@ -0,0 +1,376 @@ +#!/usr/bin/env python +# +# Copyright 2010 Facebook +# +# 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. + +"""`StackContext` allows applications to maintain threadlocal-like state +that follows execution as it moves to other execution contexts. + +The motivating examples are to eliminate the need for explicit +``async_callback`` wrappers (as in `tornado.web.RequestHandler`), and to +allow some additional context to be kept for logging. + +This is slightly magic, but it's an extension of the idea that an +exception handler is a kind of stack-local state and when that stack +is suspended and resumed in a new context that state needs to be +preserved. `StackContext` shifts the burden of restoring that state +from each call site (e.g. wrapping each `.AsyncHTTPClient` callback +in ``async_callback``) to the mechanisms that transfer control from +one context to another (e.g. `.AsyncHTTPClient` itself, `.IOLoop`, +thread pools, etc). + +Example usage:: + + @contextlib.contextmanager + def die_on_error(): + try: + yield + except Exception: + logging.error("exception in asynchronous operation",exc_info=True) + sys.exit(1) + + with StackContext(die_on_error): + # Any exception thrown here *or in callback and its desendents* + # will cause the process to exit instead of spinning endlessly + # in the ioloop. + http_client.fetch(url, callback) + ioloop.start() + +Most applications shouln't have to work with `StackContext` directly. +Here are a few rules of thumb for when it's necessary: + +* If you're writing an asynchronous library that doesn't rely on a + stack_context-aware library like `tornado.ioloop` or `tornado.iostream` + (for example, if you're writing a thread pool), use + `.stack_context.wrap()` before any asynchronous operations to capture the + stack context from where the operation was started. + +* If you're writing an asynchronous library that has some shared + resources (such as a connection pool), create those shared resources + within a ``with stack_context.NullContext():`` block. This will prevent + ``StackContexts`` from leaking from one request to another. + +* If you want to write something like an exception handler that will + persist across asynchronous calls, create a new `StackContext` (or + `ExceptionStackContext`), and make your asynchronous calls in a ``with`` + block that references your `StackContext`. +""" + +from __future__ import absolute_import, division, print_function, with_statement + +import sys +import threading + +from .util import raise_exc_info + + +class StackContextInconsistentError(Exception): + pass + + +class _State(threading.local): + def __init__(self): + self.contexts = (tuple(), None) +_state = _State() + + +class StackContext(object): + """Establishes the given context as a StackContext that will be transferred. + + Note that the parameter is a callable that returns a context + manager, not the context itself. That is, where for a + non-transferable context manager you would say:: + + with my_context(): + + StackContext takes the function itself rather than its result:: + + with StackContext(my_context): + + The result of ``with StackContext() as cb:`` is a deactivation + callback. Run this callback when the StackContext is no longer + needed to ensure that it is not propagated any further (note that + deactivating a context does not affect any instances of that + context that are currently pending). This is an advanced feature + and not necessary in most applications. + """ + def __init__(self, context_factory): + self.context_factory = context_factory + self.contexts = [] + self.active = True + + def _deactivate(self): + self.active = False + + # StackContext protocol + def enter(self): + context = self.context_factory() + self.contexts.append(context) + context.__enter__() + + def exit(self, type, value, traceback): + context = self.contexts.pop() + context.__exit__(type, value, traceback) + + # Note that some of this code is duplicated in ExceptionStackContext + # below. ExceptionStackContext is more common and doesn't need + # the full generality of this class. + def __enter__(self): + self.old_contexts = _state.contexts + self.new_contexts = (self.old_contexts[0] + (self,), self) + _state.contexts = self.new_contexts + + try: + self.enter() + except: + _state.contexts = self.old_contexts + raise + + return self._deactivate + + def __exit__(self, type, value, traceback): + try: + self.exit(type, value, traceback) + finally: + final_contexts = _state.contexts + _state.contexts = self.old_contexts + + # Generator coroutines and with-statements with non-local + # effects interact badly. Check here for signs of + # the stack getting out of sync. + # Note that this check comes after restoring _state.context + # so that if it fails things are left in a (relatively) + # consistent state. + if final_contexts is not self.new_contexts: + raise StackContextInconsistentError( + 'stack_context inconsistency (may be caused by yield ' + 'within a "with StackContext" block)') + + # Break up a reference to itself to allow for faster GC on CPython. + self.new_contexts = None + + +class ExceptionStackContext(object): + """Specialization of StackContext for exception handling. + + The supplied ``exception_handler`` function will be called in the + event of an uncaught exception in this context. The semantics are + similar to a try/finally clause, and intended use cases are to log + an error, close a socket, or similar cleanup actions. The + ``exc_info`` triple ``(type, value, traceback)`` will be passed to the + exception_handler function. + + If the exception handler returns true, the exception will be + consumed and will not be propagated to other exception handlers. + """ + def __init__(self, exception_handler): + self.exception_handler = exception_handler + self.active = True + + def _deactivate(self): + self.active = False + + def exit(self, type, value, traceback): + if type is not None: + return self.exception_handler(type, value, traceback) + + def __enter__(self): + self.old_contexts = _state.contexts + self.new_contexts = (self.old_contexts[0], self) + _state.contexts = self.new_contexts + + return self._deactivate + + def __exit__(self, type, value, traceback): + try: + if type is not None: + return self.exception_handler(type, value, traceback) + finally: + final_contexts = _state.contexts + _state.contexts = self.old_contexts + + if final_contexts is not self.new_contexts: + raise StackContextInconsistentError( + 'stack_context inconsistency (may be caused by yield ' + 'within a "with StackContext" block)') + + # Break up a reference to itself to allow for faster GC on CPython. + self.new_contexts = None + + +class NullContext(object): + """Resets the `StackContext`. + + Useful when creating a shared resource on demand (e.g. an + `.AsyncHTTPClient`) where the stack that caused the creating is + not relevant to future operations. + """ + def __enter__(self): + self.old_contexts = _state.contexts + _state.contexts = (tuple(), None) + + def __exit__(self, type, value, traceback): + _state.contexts = self.old_contexts + + +def _remove_deactivated(contexts): + """Remove deactivated handlers from the chain""" + # Clean ctx handlers + stack_contexts = tuple([h for h in contexts[0] if h.active]) + + # Find new head + head = contexts[1] + while head is not None and not head.active: + head = head.old_contexts[1] + + # Process chain + ctx = head + while ctx is not None: + parent = ctx.old_contexts[1] + + while parent is not None: + if parent.active: + break + ctx.old_contexts = parent.old_contexts + parent = parent.old_contexts[1] + + ctx = parent + + return (stack_contexts, head) + + +def wrap(fn): + """Returns a callable object that will restore the current `StackContext` + when executed. + + Use this whenever saving a callback to be executed later in a + different execution context (either in a different thread or + asynchronously in the same thread). + """ + # Check if function is already wrapped + if fn is None or hasattr(fn, '_wrapped'): + return fn + + # Capture current stack head + # TODO: Any other better way to store contexts and update them in wrapped function? + cap_contexts = [_state.contexts] + + def wrapped(*args, **kwargs): + ret = None + try: + # Capture old state + current_state = _state.contexts + + # Remove deactivated items + cap_contexts[0] = contexts = _remove_deactivated(cap_contexts[0]) + + # Force new state + _state.contexts = contexts + + # Current exception + exc = (None, None, None) + top = None + + # Apply stack contexts + last_ctx = 0 + stack = contexts[0] + + # Apply state + for n in stack: + try: + n.enter() + last_ctx += 1 + except: + # Exception happened. Record exception info and store top-most handler + exc = sys.exc_info() + top = n.old_contexts[1] + + # Execute callback if no exception happened while restoring state + if top is None: + try: + ret = fn(*args, **kwargs) + except: + exc = sys.exc_info() + top = contexts[1] + + # If there was exception, try to handle it by going through the exception chain + if top is not None: + exc = _handle_exception(top, exc) + else: + # Otherwise take shorter path and run stack contexts in reverse order + while last_ctx > 0: + last_ctx -= 1 + c = stack[last_ctx] + + try: + c.exit(*exc) + except: + exc = sys.exc_info() + top = c.old_contexts[1] + break + else: + top = None + + # If if exception happened while unrolling, take longer exception handler path + if top is not None: + exc = _handle_exception(top, exc) + + # If exception was not handled, raise it + if exc != (None, None, None): + raise_exc_info(exc) + finally: + _state.contexts = current_state + return ret + + wrapped._wrapped = True + return wrapped + + +def _handle_exception(tail, exc): + while tail is not None: + try: + if tail.exit(*exc): + exc = (None, None, None) + except: + exc = sys.exc_info() + + tail = tail.old_contexts[1] + + return exc + + +def run_with_stack_context(context, func): + """Run a coroutine ``func`` in the given `StackContext`. + + It is not safe to have a ``yield`` statement within a ``with StackContext`` + block, so it is difficult to use stack context with `.gen.coroutine`. + This helper function runs the function in the correct context while + keeping the ``yield`` and ``with`` statements syntactically separate. + + Example:: + + @gen.coroutine + def incorrect(): + with StackContext(ctx): + # ERROR: this will raise StackContextInconsistentError + yield other_coroutine() + + @gen.coroutine + def correct(): + yield run_with_stack_context(StackContext(ctx), other_coroutine) + + .. versionadded:: 3.1 + """ + with context: + return func() diff --git a/external_libs/python/zmq/eventloop/minitornado/util.py b/external_libs/python/zmq/eventloop/minitornado/util.py new file mode 100644 index 00000000..c1e2eb95 --- /dev/null +++ b/external_libs/python/zmq/eventloop/minitornado/util.py @@ -0,0 +1,184 @@ +"""Miscellaneous utility functions and classes. + +This module is used internally by Tornado. It is not necessarily expected +that the functions and classes defined here will be useful to other +applications, but they are documented here in case they are. + +The one public-facing part of this module is the `Configurable` class +and its `~Configurable.configure` method, which becomes a part of the +interface of its subclasses, including `.AsyncHTTPClient`, `.IOLoop`, +and `.Resolver`. +""" + +from __future__ import absolute_import, division, print_function, with_statement + +import sys + + +def import_object(name): + """Imports an object by name. + + import_object('x') is equivalent to 'import x'. + import_object('x.y.z') is equivalent to 'from x.y import z'. + + >>> import tornado.escape + >>> import_object('tornado.escape') is tornado.escape + True + >>> import_object('tornado.escape.utf8') is tornado.escape.utf8 + True + >>> import_object('tornado') is tornado + True + >>> import_object('tornado.missing_module') + Traceback (most recent call last): + ... + ImportError: No module named missing_module + """ + if name.count('.') == 0: + return __import__(name, None, None) + + parts = name.split('.') + obj = __import__('.'.join(parts[:-1]), None, None, [parts[-1]], 0) + try: + return getattr(obj, parts[-1]) + except AttributeError: + raise ImportError("No module named %s" % parts[-1]) + + +# Fake unicode literal support: Python 3.2 doesn't have the u'' marker for +# literal strings, and alternative solutions like "from __future__ import +# unicode_literals" have other problems (see PEP 414). u() can be applied +# to ascii strings that include \u escapes (but they must not contain +# literal non-ascii characters). +if type('') is not type(b''): + def u(s): + return s + bytes_type = bytes + unicode_type = str + basestring_type = str +else: + def u(s): + return s.decode('unicode_escape') + bytes_type = str + unicode_type = unicode + basestring_type = basestring + + +if sys.version_info > (3,): + exec(""" +def raise_exc_info(exc_info): + raise exc_info[1].with_traceback(exc_info[2]) + +def exec_in(code, glob, loc=None): + if isinstance(code, str): + code = compile(code, '<string>', 'exec', dont_inherit=True) + exec(code, glob, loc) +""") +else: + exec(""" +def raise_exc_info(exc_info): + raise exc_info[0], exc_info[1], exc_info[2] + +def exec_in(code, glob, loc=None): + if isinstance(code, basestring): + # exec(string) inherits the caller's future imports; compile + # the string first to prevent that. + code = compile(code, '<string>', 'exec', dont_inherit=True) + exec code in glob, loc +""") + + +class Configurable(object): + """Base class for configurable interfaces. + + A configurable interface is an (abstract) class whose constructor + acts as a factory function for one of its implementation subclasses. + The implementation subclass as well as optional keyword arguments to + its initializer can be set globally at runtime with `configure`. + + By using the constructor as the factory method, the interface + looks like a normal class, `isinstance` works as usual, etc. This + pattern is most useful when the choice of implementation is likely + to be a global decision (e.g. when `~select.epoll` is available, + always use it instead of `~select.select`), or when a + previously-monolithic class has been split into specialized + subclasses. + + Configurable subclasses must define the class methods + `configurable_base` and `configurable_default`, and use the instance + method `initialize` instead of ``__init__``. + """ + __impl_class = None + __impl_kwargs = None + + def __new__(cls, **kwargs): + base = cls.configurable_base() + args = {} + if cls is base: + impl = cls.configured_class() + if base.__impl_kwargs: + args.update(base.__impl_kwargs) + else: + impl = cls + args.update(kwargs) + instance = super(Configurable, cls).__new__(impl) + # initialize vs __init__ chosen for compatiblity with AsyncHTTPClient + # singleton magic. If we get rid of that we can switch to __init__ + # here too. + instance.initialize(**args) + return instance + + @classmethod + def configurable_base(cls): + """Returns the base class of a configurable hierarchy. + + This will normally return the class in which it is defined. + (which is *not* necessarily the same as the cls classmethod parameter). + """ + raise NotImplementedError() + + @classmethod + def configurable_default(cls): + """Returns the implementation class to be used if none is configured.""" + raise NotImplementedError() + + def initialize(self): + """Initialize a `Configurable` subclass instance. + + Configurable classes should use `initialize` instead of ``__init__``. + """ + + @classmethod + def configure(cls, impl, **kwargs): + """Sets the class to use when the base class is instantiated. + + Keyword arguments will be saved and added to the arguments passed + to the constructor. This can be used to set global defaults for + some parameters. + """ + base = cls.configurable_base() + if isinstance(impl, (unicode_type, bytes_type)): + impl = import_object(impl) + if impl is not None and not issubclass(impl, cls): + raise ValueError("Invalid subclass of %s" % cls) + base.__impl_class = impl + base.__impl_kwargs = kwargs + + @classmethod + def configured_class(cls): + """Returns the currently configured class.""" + base = cls.configurable_base() + if cls.__impl_class is None: + base.__impl_class = cls.configurable_default() + return base.__impl_class + + @classmethod + def _save_configuration(cls): + base = cls.configurable_base() + return (base.__impl_class, base.__impl_kwargs) + + @classmethod + def _restore_configuration(cls, saved): + base = cls.configurable_base() + base.__impl_class = saved[0] + base.__impl_kwargs = saved[1] + |