""" Back-ported, durable, and portable selectors """

# MIT License

#

# Copyright (c) 2017 Seth Michael Larson

#

# Permission is hereby granted, free of charge, to any person obtaining a copy

# of this software and associated documentation files (the "Software"), to deal

# in the Software without restriction, including without limitation the rights

# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

# copies of the Software, and to permit persons to whom the Software is

# furnished to do so, subject to the following conditions:

#

# The above copyright notice and this permission notice shall be included in all

# copies or substantial portions of the Software.

#

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

# SOFTWARE.

from __future__ import absolute_import

import collections

import errno

import math

import select

import socket

import sys

import time

namedtuple = collections.namedtuple

Mapping = collections.Mapping

try:

    monotonic = time.monotonic

except AttributeError:

    monotonic = time.time

__author__ = 'Seth Michael Larson'

__email__ = 'sethmichaellarson@protonmail.com'

__version__ = '2.0.0'

__license__ = 'MIT'

__url__ = 'https://www.github.com/SethMichaelLarson/selectors2'

__all__ = ['EVENT_READ',

           'EVENT_WRITE',

           'SelectorKey',

           'DefaultSelector',

           'BaseSelector']

EVENT_READ = (1 << 0)

EVENT_WRITE = (1 << 1)

_DEFAULT_SELECTOR = None

_SYSCALL_SENTINEL = object()  # Sentinel in case a system call returns None.

_ERROR_TYPES = (OSError, IOError, socket.error)

SelectorKey = namedtuple('SelectorKey', ['fileobj', 'fd', 'events', 'data'])

class _SelectorMapping(Mapping):

    """ Mapping of file objects to selector keys """

    def __init__(self, selector):

        self._selector = selector

    def __len__(self):

        return len(self._selector._fd_to_key)

    def __getitem__(self, fileobj):

        try:

            fd = self._selector._fileobj_lookup(fileobj)

            return self._selector._fd_to_key[fd]

        except KeyError:

            raise KeyError("{0!r} is not registered.".format(fileobj))

    def __iter__(self):

        return iter(self._selector._fd_to_key)

def _fileobj_to_fd(fileobj):

    """ Return a file descriptor from a file object. If

    given an integer will simply return that integer back. """

    if isinstance(fileobj, int):

        fd = fileobj

    else:

        try:

            fd = int(fileobj.fileno())

        except (AttributeError, TypeError, ValueError):

            raise ValueError("Invalid file object: {0!r}".format(fileobj))

    if fd < 0:

        raise ValueError("Invalid file descriptor: {0}".format(fd))

    return fd

class BaseSelector(object):

    """ Abstract Selector class

    A selector supports registering file objects to be monitored

    for specific I/O events.

    A file object is a file descriptor or any object with a

    `fileno()` method. An arbitrary object can be attached to the

    file object which can be used for example to store context info,

    a callback, etc.

    A selector can use various implementations (select(), poll(), epoll(),

    and kqueue()) depending on the platform. The 'DefaultSelector' class uses

    the most efficient implementation for the current platform.

    """

    def __init__(self):

        # Maps file descriptors to keys.

        self._fd_to_key = {}

        # Read-only mapping returned by get_map()

        self._map = _SelectorMapping(self)

    def _fileobj_lookup(self, fileobj):

        """ Return a file descriptor from a file object.

        This wraps _fileobj_to_fd() to do an exhaustive

        search in case the object is invalid but we still

        have it in our map. Used by unregister() so we can

        unregister an object that was previously registered

        even if it is closed. It is also used by _SelectorMapping

        """

        try:

            return _fileobj_to_fd(fileobj)

        except ValueError:

            # Search through all our mapped keys.

            for key in self._fd_to_key.values():

                if key.fileobj is fileobj:

                    return key.fd

            # Raise ValueError after all.

            raise

    def register(self, fileobj, events, data=None):

        """ Register a file object for a set of events to monitor. """

        if (not events) or (events & ~(EVENT_READ | EVENT_WRITE)):

            raise ValueError("Invalid events: {0!r}".format(events))

        key = SelectorKey(fileobj, self._fileobj_lookup(fileobj), events, data)

        if key.fd in self._fd_to_key:

            raise KeyError("{0!r} (FD {1}) is already registered"

                           .format(fileobj, key.fd))

        self._fd_to_key[key.fd] = key

        return key

    def unregister(self, fileobj):

        """ Unregister a file object from being monitored. """

        try:

            key = self._fd_to_key.pop(self._fileobj_lookup(fileobj))

        except KeyError:

            raise KeyError("{0!r} is not registered".format(fileobj))

        # Getting the fileno of a closed socket on Windows errors with EBADF.

        except socket.error as err:

            if err.errno != errno.EBADF:

                raise

            else:

                for key in self._fd_to_key.values():

                    if key.fileobj is fileobj:

                        self._fd_to_key.pop(key.fd)

                        break

                else:

                    raise KeyError("{0!r} is not registered".format(fileobj))

        return key

    def modify(self, fileobj, events, data=None):

        """ Change a registered file object monitored events and data. """

        # NOTE: Some subclasses optimize this operation even further.

        try:

            key = self._fd_to_key[self._fileobj_lookup(fileobj)]

        except KeyError:

            raise KeyError("{0!r} is not registered".format(fileobj))

        if events != key.events:

            self.unregister(fileobj)

            key = self.register(fileobj, events, data)

        elif data != key.data:

            # Use a shortcut to update the data.

            key = key._replace(data=data)

            self._fd_to_key[key.fd] = key

        return key

    def select(self, timeout=None):

        """ Perform the actual selection until some monitored file objects

        are ready or the timeout expires. """

        raise NotImplementedError()

    def close(self):

        """ Close the selector. This must be called to ensure that all

        underlying resources are freed. """

        self._fd_to_key.clear()

        self._map = None

    def get_key(self, fileobj):

        """ Return the key associated with a registered file object. """

        mapping = self.get_map()

        if mapping is None:

            raise RuntimeError("Selector is closed")

        try:

            return mapping[fileobj]

        except KeyError:

            raise KeyError("{0!r} is not registered".format(fileobj))

    def get_map(self):

        """ Return a mapping of file objects to selector keys """

        return self._map

    def _key_from_fd(self, fd):

        """ Return the key associated to a given file descriptor

         Return None if it is not found. """

        try:

            return self._fd_to_key[fd]

        except KeyError:

            return None

    def __enter__(self):

        return self

    def __exit__(self, *_):

        self.close()

# Almost all platforms have select.select()

if hasattr(select, "select"):

    class SelectSelector(BaseSelector):

        """ Select-based selector. """

        def __init__(self):

            super(SelectSelector, self).__init__()

            self._readers = set()

            self._writers = set()

        def register(self, fileobj, events, data=None):

            key = super(SelectSelector, self).register(fileobj, events, data)

            if events & EVENT_READ:

                self._readers.add(key.fd)

            if events & EVENT_WRITE:

                self._writers.add(key.fd)

            return key

        def unregister(self, fileobj):

            key = super(SelectSelector, self).unregister(fileobj)

            self._readers.discard(key.fd)

            self._writers.discard(key.fd)

            return key

        def select(self, timeout=None):

            # Selecting on empty lists on Windows errors out.

            if not len(self._readers) and not len(self._writers):

                return []

            timeout = None if timeout is None else max(timeout, 0.0)

            ready = []

            r, w, _ = _syscall_wrapper(self._wrap_select, True, self._readers,

                                       self._writers, timeout)

            r = set(r)

            w = set(w)

            for fd in r | w:

                events = 0

                if fd in r:

                    events |= EVENT_READ

                if fd in w:

                    events |= EVENT_WRITE

                key = self._key_from_fd(fd)

                if key:

                    ready.append((key, events & key.events))

            return ready

        def _wrap_select(self, r, w, timeout=None):

            """ Wrapper for select.select because timeout is a positional arg """

            return select.select(r, w, [], timeout)

    __all__.append('SelectSelector')

    # Jython has a different implementation of .fileno() for socket objects.

    if pycompat.isjython:

        class _JythonSelectorMapping(object):

            """ This is an implementation of _SelectorMapping that is built

            for use specifically with Jython, which does not provide a hashable

            value from socket.socket.fileno(). """

            def __init__(self, selector):

                assert isinstance(selector, JythonSelectSelector)

                self._selector = selector

            def __len__(self):

                return len(self._selector._sockets)

            def __getitem__(self, fileobj):

                for sock, key in self._selector._sockets:

                    if sock is fileobj:

                        return key

                else:

                    raise KeyError("{0!r} is not registered.".format(fileobj))

        class JythonSelectSelector(SelectSelector):

            """ This is an implementation of SelectSelector that is for Jython

            which works around that Jython's socket.socket.fileno() does not

            return an integer fd value. All SelectorKey.fd will be equal to -1

            and should not be used. This instead uses object id to compare fileobj

            and will only use select.select as it's the only selector that allows

            directly passing in socket objects rather than registering fds.

            See: http://bugs.jython.org/issue1678

                 https://wiki.python.org/jython/NewSocketModule#socket.fileno.28.29_does_not_return_an_integer

            """

            def __init__(self):

                super(JythonSelectSelector, self).__init__()

                self._sockets = []  # Uses a list of tuples instead of dictionary.

                self._map = _JythonSelectorMapping(self)

                self._readers = []

                self._writers = []

                # Jython has a select.cpython_compatible_select function in older versions.

                self._select_func = getattr(select, 'cpython_compatible_select', select.select)

            def register(self, fileobj, events, data=None):

                for sock, _ in self._sockets:

                    if sock is fileobj:

                        raise KeyError("{0!r} is already registered"

                                       .format(fileobj, sock))

                key = SelectorKey(fileobj, -1, events, data)

                self._sockets.append((fileobj, key))

                if events & EVENT_READ:

                    self._readers.append(fileobj)

                if events & EVENT_WRITE:

                    self._writers.append(fileobj)

                return key

            def unregister(self, fileobj):

                for i, (sock, key) in enumerate(self._sockets):

                    if sock is fileobj:

                        break

                else:

                    raise KeyError("{0!r} is not registered.".format(fileobj))

                if key.events & EVENT_READ:

                    self._readers.remove(fileobj)

                if key.events & EVENT_WRITE:

                    self._writers.remove(fileobj)

                del self._sockets[i]

                return key

            def _wrap_select(self, r, w, timeout=None):

                """ Wrapper for select.select because timeout is a positional arg """

                return self._select_func(r, w, [], timeout)

        __all__.append('JythonSelectSelector')

        SelectSelector = JythonSelectSelector  # Override so the wrong selector isn't used.

if hasattr(select, "poll"):

    class PollSelector(BaseSelector):

        """ Poll-based selector """

        def __init__(self):

            super(PollSelector, self).__init__()

            self._poll = select.poll()

        def register(self, fileobj, events, data=None):

            key = super(PollSelector, self).register(fileobj, events, data)

            event_mask = 0

            if events & EVENT_READ:

                event_mask |= select.POLLIN

            if events & EVENT_WRITE:

                event_mask |= select.POLLOUT

            self._poll.register(key.fd, event_mask)

            return key

        def unregister(self, fileobj):

            key = super(PollSelector, self).unregister(fileobj)

            self._poll.unregister(key.fd)

            return key

        def _wrap_poll(self, timeout=None):

            """ Wrapper function for select.poll.poll() so that

            _syscall_wrapper can work with only seconds. """

            if timeout is not None:

                if timeout <= 0:

                    timeout = 0

                else:

                    # select.poll.poll() has a resolution of 1 millisecond,

                    # round away from zero to wait *at least* timeout seconds.

                    timeout = math.ceil(timeout * 1000)

            result = self._poll.poll(timeout)

            return result

        def select(self, timeout=None):

            ready = []

            fd_events = _syscall_wrapper(self._wrap_poll, True, timeout=timeout)

            for fd, event_mask in fd_events:

                events = 0

                if event_mask & ~select.POLLIN:

                    events |= EVENT_WRITE

                if event_mask & ~select.POLLOUT:

                    events |= EVENT_READ