client: replace Event by a pipe as a way to stop the poll loop

This is a prerequisite for tickless poll loops.

neo/client/poll.py

@@ -15,18 +15,19 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 from logging import DEBUG, ERROR
-from threading import Thread, Event, enumerate as thread_enum
+from threading import Thread, enumerate as thread_enum
 from neo.lib import logging
 from neo.lib.locking import Lock
 
 class _ThreadedPoll(Thread):
     """Polling thread."""
 
+    stopping = False
+
     def __init__(self, em, **kw):
         Thread.__init__(self, **kw)
         self.em = em
         self.daemon = True
-        self._stop = Event()
 
     def run(self):
         _log = logging.log
@@ -34,25 +35,24 @@ class _ThreadedPoll(Thread):
             # Ignore errors due to garbage collection on exit
             try:
                 _log(*args, **kw)
-            except:
-                if not self.stopping():
+            except Exception:
+                if not self.stopping:
                     raise
         log(DEBUG, 'Started %s', self)
-        while not self.stopping():
         try:
-                # XXX: Delay cannot be infinite here, because we need
-                #      to check connection timeout and thread shutdown.
+            while 1:
+                try:
+                    # XXX: Delay can't be infinite here, because we need
+                    #      to check connection timeouts.
                     self.em.poll(1)
-            except:
+                except Exception:
                     log(ERROR, 'poll raised, retrying', exc_info=1)
+        finally:
             log(DEBUG, 'Threaded poll stopped')
-        self._stop.clear()
 
     def stop(self):
-        self._stop.set()
-
-    def stopping(self):
-        return self._stop.isSet()
+        self.stopping = True
+        self.em.wakeup(True)
 
 class ThreadedPoll(object):
     """
@@ -81,7 +81,7 @@ class ThreadedPoll(object):
         self._status_lock_acquire()
         try:
             thread = self._thread
-            if thread.stopping():
+            if thread.stopping:
                 # XXX: ideally, we should wake thread up here, to be sure not
                 # to wait forever.
                 thread.join()

neo/lib/event.py

@@ -14,22 +14,30 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import os, thread
 from time import time
 from select import epoll, EPOLLIN, EPOLLOUT, EPOLLERR, EPOLLHUP
-from errno import EAGAIN, EINTR, ENOENT
+from errno import EAGAIN, EEXIST, EINTR, ENOENT
 from . import logging
+from .locking import Lock
 
 class EpollEventManager(object):
     """This class manages connections and events based on epoll(5)."""
 
+    _trigger_exit = False
+
     def __init__(self):
         self.connection_dict = {}
         self.reader_set = set()
         self.writer_set = set()
         self.epoll = epoll()
         self._pending_processing = []
+        self._trigger_fd, w = os.pipe()
+        os.close(w)
+        self._trigger_lock = Lock()
 
     def close(self):
+        os.close(self._trigger_fd)
         for c in self.connection_dict.values():
             c.close()
         del self.__dict__
@@ -150,6 +158,12 @@ class EpollEventManager(object):
             try:
                 conn = self.connection_dict[fd]
             except KeyError:
+                if fd == self._trigger_fd:
+                    with self._trigger_lock:
+                        self.epoll.unregister(fd)
+                        if self._trigger_exit:
+                            del self._trigger_exit
+                            thread.exit()
                 continue
             if conn.readable():
                 self._addPendingConnection(conn)
@@ -158,6 +172,16 @@ class EpollEventManager(object):
         for conn in self.connection_dict.values():
             conn.checkTimeout(t)
 
+    def wakeup(self, exit=False):
+        with self._trigger_lock:
+            self._trigger_exit |= exit
+            try:
+                self.epoll.register(self._trigger_fd)
+            except IOError, e:
+                # Ignore if 'wakeup' is called several times in a row.
+                if e.errno != EEXIST:
+                    raise
+
     def addReader(self, conn):
         connector = conn.getConnector()
         assert connector is not None, conn.whoSetConnector()