self._operations should use a deque() which is O(1)

[lukemarsden]

I've just fixed this in a sibling of the txMySQL codebase, due to O(N) performance append()ing and pop(0)ing from lists, this should be a decent performance win in any case where there are around > 1000 queued queries.

[lukemarsden]

NB In txMySQL this is spelled self._pending_operations.

[lukemarsden]

The following patch gives the gist:

+from collections import deque

 CancellableDeferredSemaphore = CancellableDeferredSemaphore
 SPREAD_PORT = 16171
@@ -499,7 +500,7 @@ class QueueEnabledMixin(object):
             from twisted.internet import reactor
             clock = reactor
         self.clock = clock
-        self._operations = []
+        self._operations = deque()
         self._current_operation = None
         self._logTag = logTag
         # For debugging
@@ -516,8 +517,8 @@ class QueueEnabledMixin(object):
         """
         HybridUtils.channelLog(self._logTag,
                 "in _do_operation, self._operations "
-                "is %r self._current_operation is %r" % (
-                    self._operations, self._current_operation))
+                "is %d long self._current_operation is %r" % (
+                    len(self._operations), self._current_operation))
         d = defer.Deferred()
         self._operations.append((d, func, a, kw))
         if self._current_operation is None:
@@ -575,7 +576,7 @@ class QueueEnabledMixin(object):
                 "is %r self._current_operation is %r" % (
                     self._operations, self._current_operation))
         if self._operations:
-            d, f, a, kw = self._operations.pop(0)
+            d, f, a, kw = self._operations.popleft()
             self._current_fn = f
             self._current_args = (a, kw)
             self._current_operation = defer.maybeDeferred(f, *a, **kw)