eventlet/gevent doesn't work well with select.poll because select.poll blocks
python interpreter as a whole instead of switching from the current thread
which is about to block to other runnable thread.
So ovsdb python binding can't be used with eventlet/gevent.
Emulate select.poll with select.select because using python means that
performance isn't so important.
Signed-off-by: Isaku Yamahata <yamah...@valinux.co.jp>
---
change v1 -> v2:
- replace select.poll with select.select for simplicity instead of
monkey patching
---
python/ovs/poller.py | 71 ++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 69 insertions(+), 2 deletions(-)
diff --git a/python/ovs/poller.py b/python/ovs/poller.py
index e459c58..e4294e3 100644
--- a/python/ovs/poller.py
+++ b/python/ovs/poller.py
@@ -13,13 +13,80 @@
# limitations under the License.
import errno
-import select
import ovs.timeval
import ovs.vlog
+import select
+import socket
vlog = ovs.vlog.Vlog("poller")
+# eventlet/gevent that does monkey patch to select module doesn't support
+# select.poll. If select.poll is used, python interpreter is blocked as a
+# whole instead of switching from the current thread that is about to block
+# to other runnable thread.
+# So emulate select.poll by select.select because python is used so that
+# performance isn't so important.
+# If eventlet/gevent isn't used, we can use select.poll by replacing
+# SelectPoll with select.poll class
+# SelectPoll = select.poll
+class _SelectSelect(object):
+ """ select.poll emulation by using select.select.
+ Only register and poll are needed at the moment.
+ """
+ def __init__(self):
+ super(_SelectSelect, self).__init__()
+ self.rlist = []
+ self.wlist = []
+ self.xlist = []
+
+ def register(self, fd, events):
+ if isinstance(fd, socket.socket):
+ fd = fd.fileno()
+ assert isinstance(fd, int)
+ if events & select.POLLIN:
+ self.rlist.append(fd)
+ events &= ~select.POLLIN
+ if events & select.POLLOUT:
+ self.wlist.append(fd)
+ events &= ~select.POLLOUT
+ if events:
+ self.xlist.append(fd)
+
+ @staticmethod
+ def _events_update(events_dict, fd, event):
+ """Emulate 'collections.defaultdict(int)[fd] |= event' with dict"""
+ events = events_dict.setdefault(fd, 0)
+ events_dict[fd] = events | event
+
+ def poll(self, timeout):
+ if timeout == -1:
+ # epoll uses -1 for indifinite timeout, select uses None.
+ timeout = None
+ else:
+ timeout = float(timeout) / 1000
+
+ rlist, wlist, xlist = select.select(self.rlist, self.wlist, self.xlist,
+ timeout)
+ # collections.defaultdict is introduced by python 2.5 and
+ # XenServer uses python 2.4. We don't use it for XenServer.
+ # events_dict = collections.defaultdict(int)
+ # events_dict[fd] |= event
+ events_dict = {}
+ for fd in rlist:
+ self._events_update(events_dict, fd, select.POLLIN)
+ for fd in wlist:
+ self._events_update(events_dict, fd, select.POLLOUT)
+ for fd in xlist:
+ self._events_update(events_dict, fd, select.POLLERR |
+ select.POLLHUP | select.POLLNVAL)
+ return [(fd, events) for (fd, events) in events_dict.items()]
+
+
+SelectPoll = _SelectSelect
+# SelectPoll = select.poll
+
+
class Poller(object):
"""High-level wrapper around the "poll" system call.
@@ -122,5 +189,5 @@ class Poller(object):
vlog.dbg("%s on fd %d" % (s, fd))
def __reset(self):
- self.poll = select.poll()
+ self.poll = SelectPoll()
self.timeout = -1
--
1.7.1.1
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