Enable merging buildbot builds dependent on queue length

third_party/buildbot_8_4p1/buildbot/process/builder.py

 # This file is part of Buildbot.  Buildbot is free software: you can
 # redistribute it and/or modify it under the terms of the GNU General Public
 # License as published by the Free Software Foundation, version 2.
 #
 # This program 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 General Public License for more
 # details.
 #
 # You should have received a copy of the GNU General Public License along with
@@ skipping 835 matching lines @@
         # we'll need BuildRequest objects, so get those first
         wfd = defer.waitForDeferred(
             defer.gatherResults(
                 [ self._brdictToBuildRequest(brdict)
                   for brdict in unclaimed_requests ]))
         yield wfd
         unclaimed_request_objects = wfd.getResult()
         breq_object = unclaimed_request_objects.pop(
                 unclaimed_requests.index(breq))
 
+        # Make sure the merge-requests function can take the queue lengths. Old
+        # style functions only take two parameters.
+        if getattr(mergeRequests_fn, 'with_length', False):
+            mergeRequests_with_length_fn = mergeRequests_fn
+        else:
+            mergeRequests_with_length_fn = (
+                lambda a, b, *_ : mergeRequests_fn(a, b))
+
+        # This might not reflect the exact number of items that could be merged
+        # (this depends on the canBeMergedWith algorithm), but it can help
+        # indicating how loaded this builder is.
+        queue_length = len(unclaimed_request_objects)
+
         # gather the mergeable requests
         merged_request_objects = [breq_object]
         for other_breq_object in unclaimed_request_objects:
             wfd = defer.waitForDeferred(
                 defer.maybeDeferred(lambda :
-                    mergeRequests_fn(breq_object, other_breq_object)))
+                    mergeRequests_with_length_fn(

[agable, 2016/10/13 17:58:36]

It might be less confusing if the "if fn.with_length" logic were down here, and
then whether you pass two or four arguments is dependent on the result of that
check, rather than always passing four and having to decode the lambda above. Up
to you, though.

[Michael Achenbach, 2016/10/13 19:05:07]

Done.

+                        breq_object,
+                        other_breq_object,
+                        queue_length, 
+                        len(merged_request_objects),
+                    )))
             yield wfd
             if wfd.getResult():
                 merged_request_objects.append(other_breq_object)
 
         # convert them back to brdicts and return
         merged_requests = [ br.brdict for br in merged_request_objects ]
         yield merged_requests
 
     def _brdictToBuildRequest(self, brdict):
         """
@@ skipping 107 matching lines @@
         d = defer.DeferredList(dl)
         d.addCallback(self._gatherPingResults)
         return d
 
     def _gatherPingResults(self, res):
         for ignored,success in res:
             if not success:
                 return False
         return True