# -*- test-case-name: twisted.test.test_internet -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Select reactor
"""

from __future__ import division, absolute_import

from time import sleep
import sys, select, socket
from errno import EINTR, EBADF

from zope.interface import implementer

from twisted.internet.interfaces import IReactorFDSet
from twisted.internet import posixbase
from twisted.python import log
from twisted.python.runtime import platformType


def win32select(r, w, e, timeout=None):
"""Win32 select wrapper."""
if not (r or w):
# windows select() exits immediately when no sockets
if timeout is None:
timeout = 0.01
else:
timeout = min(timeout, 0.001)
sleep(timeout)
return [], [], []
# windows doesn't process 'signals' inside select(), so we set a max
# time or ctrl-c will never be recognized
if timeout is None or timeout > 0.5:
timeout = 0.5
r, w, e = select.select(r, w, w, timeout)
return r, w + e, []

if platformType == "win32":
_select = win32select
else:
_select = select.select


try:
from twisted.internet.win32eventreactor import _ThreadedWin32EventsMixin
except ImportError:
_extraBase = object
else:
_extraBase = _ThreadedWin32EventsMixin


@implementer(IReactorFDSet)
class SelectReactor(posixbase.PosixReactorBase, _extraBase):
"""
A select() based reactor - runs on all POSIX platforms and on Win32.

@ivar _reads: A dictionary mapping L{FileDescriptor} instances to arbitrary
values (this is essentially a set). Keys in this dictionary will be
checked for read events.

@ivar _writes: A dictionary mapping L{FileDescriptor} instances to
arbitrary values (this is essentially a set). Keys in this dictionary
will be checked for writability.
"""

def __init__(self):
"""
Initialize file descriptor tracking dictionaries and the base class.
"""
self._reads = {}
self._writes = {}
posixbase.PosixReactorBase.__init__(self)


def _preenDescriptors(self):
log.msg("Malformed file descriptor found. Preening lists.")
readers = list(self._reads.keys())
writers = list(self._writes.keys())
self._reads.clear()
self._writes.clear()
for selDict, selList in ((self._reads, readers),
(self._writes, writers)):
for selectable in selList:
try:
select.select([selectable], [selectable], [selectable], 0)
except Exception as e:
log.msg("bad descriptor %s" % selectable)
self._disconnectSelectable(selectable, e, False)
else:
selDict[selectable] = 1


def doSelect(self, timeout):
"""
Run one iteration of the I/O monitor loop.

This will run all selectables who had input or output readiness
waiting for them.
"""
try:
r, w, ignored = _select(self._reads.keys(),
self._writes.keys(),
[], timeout)
except ValueError:
# Possibly a file descriptor has gone negative?
self._preenDescriptors()
return
except TypeError:
# Something *totally* invalid (object w/o fileno, non-integral
# result) was passed
log.err()
self._preenDescriptors()
return
except (select.error, socket.error, IOError) as se:
# select(2) encountered an error, perhaps while calling the fileno()
# method of a socket. (Python 2.6 socket.error is an IOError
# subclass, but on Python 2.5 and earlier it is not.)
if se.args[0] in (0, 2):
# windows does this if it got an empty list
if (not self._reads) and (not self._writes):
return
else:
raise
elif se.args[0] == EINTR:
return
elif se.args[0] == EBADF:
self._preenDescriptors()
return
else:
# OK, I really don't know what's going on. Blow up.
raise

_drdw = self._doReadOrWrite
_logrun = log.callWithLogger
for selectables, method, fdset in ((r, "doRead", self._reads),
(w,"doWrite", self._writes)):
for selectable in selectables:
# if this was disconnected in another thread, kill it.
# ^^^^ --- what the !@#*? serious! -exarkun
if selectable not in fdset:
continue
# This for pausing input when we're not ready for more.
_logrun(selectable, _drdw, selectable, method)

doIteration = doSelect

def _doReadOrWrite(self, selectable, method):
try:
why = getattr(selectable, method)()
except:
why = sys.exc_info()[1]
log.err()
if why:
self._disconnectSelectable(selectable, why, method=="doRead")

def addReader(self, reader):
"""
Add a FileDescriptor for notification of data available to read.
"""
self._reads[reader] = 1

def addWriter(self, writer):
"""
Add a FileDescriptor for notification of data available to write.
"""
self._writes[writer] = 1

def removeReader(self, reader):
"""
Remove a Selectable for notification of data available to read.
"""
if reader in self._reads:
del self._reads[reader]

def removeWriter(self, writer):
"""
Remove a Selectable for notification of data available to write.
"""
if writer in self._writes:
del self._writes[writer]

def removeAll(self):
return self._removeAll(self._reads, self._writes)


def getReaders(self):
return list(self._reads.keys())


def getWriters(self):
return list(self._writes.keys())



def install():
"""Configure the twisted mainloop to be run using the select() reactor.
"""
reactor = SelectReactor()
from twisted.internet.main import installReactor
installReactor(reactor)

__all__ = ['install']