Only calculate slave->build mapping once in json output.

third_party/buildbot_8_4p1/buildbot/status/web/status_json.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
 # this program; if not, write to the Free Software Foundation, Inc., 51
 # Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 #
 # Portions Copyright Buildbot Team Members
 # Original Copyright (c) 2010 The Chromium Authors.
 
 """Simple JSON exporter."""
 
+import collections
 import datetime
 import os
 import re
 
 from twisted.internet import defer
 from twisted.web import html, resource, server
 
 from buildbot.status.web.base import HtmlResource
 from buildbot.util import json
 
@@ skipping 378 matching lines @@
                           BuilderJsonResource(status,
                                               status.getBuilder(builder_name)))
 
 
 class BuilderSlavesJsonResources(JsonResource):
     help = """Describe the slaves attached to a single builder.
 """
     pageTitle = 'BuilderSlaves'
 
     def __init__(self, status, builder_status):
+        buildcache = collections.defaultdict(dict)

[M-A Ruel, 2013/04/06 01:23:46]

Why not create a single global instance? It'd be simpler and more efficient.

[Mike Stip (use stip instead), 2013/04/06 01:30:28]

Because this is per-request. It's only a cache while the JSON is being build up,
then it should be discarded.

         JsonResource.__init__(self, status)
         self.builder_status = builder_status
         for slave_name in self.builder_status.slavenames:
             self.putChild(slave_name,
                           SlaveJsonResource(status,
-                                            self.status.getSlave(slave_name)))
+                                            self.status.getSlave(slave_name),
+                                            buildcache=buildcache))
 
 
 class BuildJsonResource(JsonResource):
     help = """Describe a single build.
 """
     pageTitle = 'Build'
 
     def __init__(self, status, build_status):
         JsonResource.__init__(self, status)
         self.build_status = build_status
@@ skipping 180 matching lines @@
 
     def asDict(self, request):
         return self.status.asDict()
 
 
 class SlaveJsonResource(JsonResource):
     help = """Describe a slave.
 """
     pageTitle = 'Slave'
 
-    def __init__(self, status, slave_status):
+    def __init__(self, status, slave_status, buildcache=None):
         JsonResource.__init__(self, status)
         self.slave_status = slave_status
         self.name = self.slave_status.getName()
         self.builders = None
 
+        # buildcache is used to cache build information across multiple
+        # invocations of SlaveJsonResource. It should be set to an empty
+        # collections.defaultdict(dict). Without it, each invocation will
+        # do a full build scan.
+        self.buildcache = buildcache or collections.defaultdict(dict)
+
     def getBuilders(self):
         if self.builders is None:
             # Figure out all the builders to which it's attached
             self.builders = []
             for builderName in self.status.getBuilderNames():
                 if self.name in self.status.getBuilder(builderName).slavenames:
                     self.builders.append(builderName)
         return self.builders
 
-    def asDict(self, request):
-        results = self.slave_status.asDict()
-        # Enhance it by adding more informations.
-        results['builders'] = {}
+    def mapSlavesToBuilds(self):

[Isaac (away), 2013/04/05 23:45:01]

delete this method and inline to line 662

[Mike Stip (use stip instead), 2013/04/06 01:30:28]

Done.

         for builderName in self.getBuilders():
             builds = []
             builder_status = self.status.getBuilder(builderName)
             for i in range(1, builder_status.buildCacheSize - 1):
                 build_status = builder_status.getBuild(-i)
                 if not build_status or not build_status.isFinished():
                     # If not finished, it will appear in runningBuilds.
                     break
-                if build_status.getSlavename() == self.name:
-                    builds.append(build_status.getNumber())
-            results['builders'][builderName] = builds
+                slave = self.buildcache[build_status.getSlavename()]
+                slave.setdefault(builderName, []).append(

[M-A Ruel, 2013/04/06 01:23:46]

Note that it is effectively a memory leak, not a big one since it's just numbers
but still.

[Mike Stip (use stip instead), 2013/04/06 01:30:28]

buildcache gets thrown away after every request.

+                        build_status.getNumber())
+
+    def getSlaveBuildMap(self):
+        if not self.buildcache:
+            self.mapSlavesToBuilds()
+        return self.buildcache[self.name]
+
+    def asDict(self, request):
+        results = self.slave_status.asDict()
+        # Enhance it by adding more informations.
+        results['builders'] = self.getSlaveBuildMap()
         return results
 
 
 class SlavesJsonResource(JsonResource):
     help = """List the registered slaves.
 """
     pageTitle = 'Slaves'
 
     def __init__(self, status):
+        buildcache = collections.defaultdict(dict)
         JsonResource.__init__(self, status)
         for slave_name in status.getSlaveNames():
             self.putChild(slave_name,
                           SlaveJsonResource(status,
-                                            status.getSlave(slave_name)))
+                                            status.getSlave(slave_name),
+                                            buildcache=buildcache))
 
 
 class SourceStampJsonResource(JsonResource):
     help = """Describe the sources for a SourceStamp.
 """
     pageTitle = 'SourceStamp'
 
     def __init__(self, status, source_stamp):
         # buildbot.sourcestamp.SourceStamp
         JsonResource.__init__(self, status)
@@ skipping 61 matching lines @@
         if not builder:
             return
         EXAMPLES = EXAMPLES.replace('<A_BUILDER>', builder.getName())
         build = builder.getBuild(-1)
         if build:
             EXAMPLES = EXAMPLES.replace('<A_BUILD>', str(build.getNumber()))
         if builder.slavenames:
             EXAMPLES = EXAMPLES.replace('<A_SLAVE>', builder.slavenames[0])
 
 # vim: set ts=4 sts=4 sw=4 et: