1 # Copyright (c) 2010, 2015 Nicira, Inc.
3 # Licensed under the Apache License, Version 2.0 (the "License");
4 # you may not use this file except in compliance with the License.
5 # You may obtain a copy of the License at:
7 # http://www.apache.org/licenses/LICENSE-2.0
9 # Unless required by applicable law or agreed to in writing, software
10 # distributed under the License is distributed on an "AS IS" BASIS,
11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 # See the License for the specific language governing permissions and
13 # limitations under the License.
22 import eventlet.patcher
24 def _using_eventlet_green_select():
25 return eventlet.patcher.is_monkey_patched(select)
27 def _using_eventlet_green_select():
30 vlog = ovs.vlog.Vlog("poller")
39 # eventlet/gevent doesn't support select.poll. If select.poll is used,
40 # python interpreter is blocked as a whole instead of switching from the
41 # current thread that is about to block to other runnable thread.
42 # So emulate select.poll by select.select because using python means that
43 # performance isn't so important.
44 class _SelectSelect(object):
45 """ select.poll emulation by using select.select.
46 Only register and poll are needed at the moment.
53 def register(self, fd, events):
54 if isinstance(fd, socket.socket):
56 assert isinstance(fd, int)
66 def poll(self, timeout):
68 # epoll uses -1 for infinite timeout, select uses None.
71 timeout = float(timeout) / 1000
72 # XXX workaround a bug in eventlet
73 # see https://github.com/eventlet/eventlet/pull/25
74 if timeout == 0 and _using_eventlet_green_select():
77 rlist, wlist, xlist = select.select(self.rlist, self.wlist, self.xlist,
81 events_dict[fd] = events_dict.get(fd, 0) | POLLIN
83 events_dict[fd] = events_dict.get(fd, 0) | POLLOUT
85 events_dict[fd] = events_dict.get(fd, 0) | (POLLERR |
88 return events_dict.items()
91 SelectPoll = _SelectSelect
92 # If eventlet/gevent isn't used, we can use select.poll by replacing
93 # _SelectPoll with select.poll class
94 # _SelectPoll = select.poll
98 """High-level wrapper around the "poll" system call.
100 Intended usage is for the program's main loop to go about its business
101 servicing whatever events it needs to. Then, when it runs out of immediate
102 tasks, it calls each subordinate module or object's "wait" function, which
103 in turn calls one (or more) of the functions Poller.fd_wait(),
104 Poller.immediate_wake(), and Poller.timer_wait() to register to be awakened
105 when the appropriate event occurs. Then the main loop calls
106 Poller.block(), which blocks until one of the registered events happens."""
111 def fd_wait(self, fd, events):
112 """Registers 'fd' as waiting for the specified 'events' (which should
113 be select.POLLIN or select.POLLOUT or their bitwise-OR). The following
114 call to self.block() will wake up when 'fd' becomes ready for one or
115 more of the requested events.
117 The event registration is one-shot: only the following call to
118 self.block() is affected. The event will need to be re-registered
119 after self.block() is called if it is to persist.
121 'fd' may be an integer file descriptor or an object with a fileno()
122 method that returns an integer file descriptor."""
123 self.poll.register(fd, events)
125 def __timer_wait(self, msec):
126 if self.timeout < 0 or msec < self.timeout:
129 def timer_wait(self, msec):
130 """Causes the following call to self.block() to block for no more than
131 'msec' milliseconds. If 'msec' is nonpositive, the following call to
132 self.block() will not block at all.
134 The timer registration is one-shot: only the following call to
135 self.block() is affected. The timer will need to be re-registered
136 after self.block() is called if it is to persist."""
138 self.immediate_wake()
140 self.__timer_wait(msec)
142 def timer_wait_until(self, msec):
143 """Causes the following call to self.block() to wake up when the
144 current time, as returned by ovs.timeval.msec(), reaches 'msec' or
145 later. If 'msec' is earlier than the current time, the following call
146 to self.block() will not block at all.
148 The timer registration is one-shot: only the following call to
149 self.block() is affected. The timer will need to be re-registered
150 after self.block() is called if it is to persist."""
151 now = ovs.timeval.msec()
153 self.immediate_wake()
155 self.__timer_wait(msec - now)
157 def immediate_wake(self):
158 """Causes the following call to self.block() to wake up immediately,
163 """Blocks until one or more of the events registered with
164 self.fd_wait() occurs, or until the minimum duration registered with
165 self.timer_wait() elapses, or not at all if self.immediate_wake() has
169 events = self.poll.poll(self.timeout)
170 self.__log_wakeup(events)
171 except select.error, e:
174 if error != errno.EINTR:
175 vlog.err("poll: %s" % e[1])
179 def __log_wakeup(self, events):
181 vlog.dbg("%d-ms timeout" % self.timeout)
183 for fd, revents in events:
188 if revents & POLLOUT:
190 if revents & POLLERR:
192 if revents & POLLHUP:
194 if revents & POLLNVAL:
196 vlog.dbg("%s on fd %d" % (s, fd))
199 self.poll = SelectPoll()