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#
# Copyright (C) 2009-2015 CEA/DAM
#
# This file is part of ClusterShell.
#
# ClusterShell is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# ClusterShell is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with ClusterShell; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
"""
A ClusterShell Engine using epoll, an I/O event notification facility.
The epoll event distribution interface is available on Linux 2.6, and
has been included in Python 2.6.
"""
import errno
import select
import time
from ClusterShell.Engine.Engine import Engine, E_READ, E_WRITE
from ClusterShell.Engine.Engine import EngineNotSupportedError
from ClusterShell.Engine.Engine import EngineTimeoutException
from ClusterShell.Worker.EngineClient import EngineClientEOF
class EngineEPoll(Engine):
"""
EPoll Engine
ClusterShell Engine class using the select.epoll mechanism.
"""
identifier = "epoll"
def __init__(self, info):
"""
Initialize Engine.
"""
Engine.__init__(self, info)
try:
# get an epoll object
self.epolling = select.epoll()
except AttributeError:
raise EngineNotSupportedError(EngineEPoll.identifier)
def release(self):
"""Release engine-specific resources."""
self.epolling.close()
def _register_specific(self, fd, event):
"""Engine-specific fd registering. Called by Engine register."""
if event & E_READ:
eventmask = select.EPOLLIN
else:
assert event & E_WRITE
eventmask = select.EPOLLOUT
self.epolling.register(fd, eventmask)
def _unregister_specific(self, fd, ev_is_set):
"""
Engine-specific fd unregistering. Called by Engine unregister.
"""
self._debug("UNREGSPEC fd=%d ev_is_set=%x"% (fd, ev_is_set))
if ev_is_set:
self.epolling.unregister(fd)
def _modify_specific(self, fd, event, setvalue):
"""
Engine-specific modifications after a interesting event change for
a file descriptor. Called automatically by Engine set_events().
For the epoll engine, it modifies the event mask associated to a file
descriptor.
"""
self._debug("MODSPEC fd=%d event=%x setvalue=%d" % (fd, event,
setvalue))
if setvalue:
self._register_specific(fd, event)
else:
self.epolling.unregister(fd)
def runloop(self, timeout):
"""
Run epoll main loop.
"""
if not timeout:
timeout = -1
start_time = time.time()
# run main event loop...
while self.evlooprefcnt > 0:
self._debug("LOOP evlooprefcnt=%d (reg_clifds=%s) (timers=%d)" % \
(self.evlooprefcnt, self.reg_clifds.keys(),
len(self.timerq)))
try:
timeo = self.timerq.nextfire_delay()
if timeout > 0 and timeo >= timeout:
# task timeout may invalidate clients timeout
self.timerq.clear()
timeo = timeout
elif timeo == -1:
timeo = timeout
self._current_loopcnt += 1
if timeo < 0:
poll_timeo = -1
else:
poll_timeo = timeo
evlist = self.epolling.poll(poll_timeo)
except IOError as ex:
# might get interrupted by a signal
if ex.errno == errno.EINTR:
continue
for fd, event in evlist:
# get client instance
client, stream = self._fd2client(fd)
if client is None:
continue
fdev = stream.evmask
sname = stream.name
# set as current processed stream
self._current_stream = stream
# check for poll error condition of some sort
if event & select.EPOLLERR:
self._debug("EPOLLERR fd=%d sname=%s fdev=0x%x (%s)" % \
(fd, sname, fdev, client))
assert fdev & E_WRITE
self.remove_stream(client, stream)
self._current_stream = None
continue
# check for data to read
if event & select.EPOLLIN:
assert fdev & E_READ
assert stream.events & fdev, (stream.events, fdev)
self.modify(client, sname, 0, fdev)
try:
client._handle_read(sname)
except EngineClientEOF:
self._debug("EngineClientEOF %s %s" % (client, sname))
self.remove_stream(client, stream)
self._current_stream = None
continue
# or check for end of stream (do not handle both at the same
# time because handle_read() may perform a partial read)
elif event & select.EPOLLHUP:
assert fdev & E_READ, "fdev 0x%x & E_READ" % fdev
self._debug("EPOLLHUP fd=%d sname=%s %s (%s)" % \
(fd, sname, client, client.streams))
self.remove_stream(client, stream)
self._current_stream = None
continue
# check for writing
if event & select.EPOLLOUT:
self._debug("EPOLLOUT fd=%d sname=%s %s (%s)" % \
(fd, sname, client, client.streams))
assert fdev & E_WRITE
assert stream.events & fdev, (stream.events, fdev)
self.modify(client, sname, 0, fdev)
client._handle_write(sname)
self._current_stream = None
# apply any changes occurred during processing
if client.registered:
self.set_events(client, stream)
# check for task runloop timeout
if timeout > 0 and time.time() >= start_time + timeout:
raise EngineTimeoutException()
# process clients timeout
self.fire_timers()
self._debug("LOOP EXIT evlooprefcnt=%d (reg_clifds=%s) (timers=%d)" % \
(self.evlooprefcnt, self.reg_clifds, len(self.timerq)))
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