Switch to the good LRU implementation.

third_party/buildbot_8_4p1/README.chromium

Index: third_party/buildbot_8_4p1/README.chromium
===================================================================
--- third_party/buildbot_8_4p1/README.chromium	(revision 127129)
+++ third_party/buildbot_8_4p1/README.chromium	(working copy)
@@ -1199,3 +1199,149 @@
          kwargs['logfiles'] = self.logfiles
  
          # check for the usePTY flag
+
+For performance, switch to the good LRU cache implementation.
+
+Index: buildbot/status/builder.py
+===================================================================
+--- buildbot/status/builder.py	(revision 127129)
++++ buildbot/status/builder.py	(working copy)
+@@ -86,8 +86,10 @@
+         self.currentBuilds = []
+         self.nextBuild = None
+         self.watchers = []
+-        self.buildCache = weakref.WeakValueDictionary()
+-        self.buildCache_LRU = []
++        #self.buildCache = weakref.WeakValueDictionary()
++        #self.buildCache_LRU = []
++        self.buildCache = util.lru.AsyncLRUCache(self.cacheMiss,
++                                                 self.buildCacheSize)
+         self.logCompressionLimit = False # default to no compression for tests
+         self.logCompressionMethod = "bz2"
+         self.logMaxSize = None # No default limit
+@@ -103,7 +105,7 @@
+         d = styles.Versioned.__getstate__(self)
+         d['watchers'] = []
+         del d['buildCache']
+-        del d['buildCache_LRU']
++        #del d['buildCache_LRU']
+         for b in self.currentBuilds:
+             b.saveYourself()
+             # TODO: push a 'hey, build was interrupted' event
+@@ -119,8 +121,10 @@
+         # when loading, re-initialize the transient stuff. Remember that
+         # upgradeToVersion1 and such will be called after this finishes.
+         styles.Versioned.__setstate__(self, d)
+-        self.buildCache = weakref.WeakValueDictionary()
+-        self.buildCache_LRU = []
++        #self.buildCache = weakref.WeakValueDictionary()
++        #self.buildCache_LRU = []
++        self.buildCache = util.lru.AsyncLRUCache(self.cacheMiss,
++                                                 self.buildCacheSize)
+         self.currentBuilds = []
+         self.watchers = []
+         self.slavenames = []
+@@ -132,6 +136,7 @@
+         # gets pickled and unpickled.
+         if buildmaster.buildCacheSize is not None:
+             self.buildCacheSize = buildmaster.buildCacheSize
++            self.buildCache.set_max_size(buildmaster.buildCacheSize)
+ 
+     def upgradeToVersion1(self):
+         if hasattr(self, 'slavename'):
+@@ -186,33 +191,24 @@
+         except:
+             log.msg("unable to save builder %s" % self.name)
+             log.err()
+-        
+ 
++
+     # build cache management
+ 
+     def makeBuildFilename(self, number):
+         return os.path.join(self.basedir, "%d" % number)
+ 
+-    def touchBuildCache(self, build):
+-        self.buildCache[build.number] = build
+-        if build in self.buildCache_LRU:
+-            self.buildCache_LRU.remove(build)
+-        self.buildCache_LRU = self.buildCache_LRU[-(self.buildCacheSize-1):] + [ build ]
+-        return build
++#    def touchBuildCache(self, build):
++#        self.buildCache[build.number] = build
++#        if build in self.buildCache_LRU:
++#            self.buildCache_LRU.remove(build)
++#        self.buildCache_LRU = self.buildCache_LRU[-(self.buildCacheSize-1):] + [ build ]
++#        return build
+ 
+     def getBuildByNumber(self, number):
+-        # first look in currentBuilds
+-        for b in self.currentBuilds:
+-            if b.number == number:
+-                return self.touchBuildCache(b)
++        return self.buildCache.get(number)
+ 
+-        # then in the buildCache
+-        if number in self.buildCache:
+-            metrics.MetricCountEvent.log("buildCache.hits", 1)
+-            return self.touchBuildCache(self.buildCache[number])
+-        metrics.MetricCountEvent.log("buildCache.misses", 1)
+-
+-        # then fall back to loading it from disk
++    def loadBuildFromFile(self, number):
+         filename = self.makeBuildFilename(number)
+         try:
+             log.msg("Loading builder %s's build %d from on-disk pickle"
+@@ -235,12 +231,23 @@
+             build.upgradeLogfiles()
+             # check that logfiles exist
+             build.checkLogfiles()
+-            return self.touchBuildCache(build)
++            #return self.touchBuildCache(build)
++            return build
+         except IOError:
+             raise IndexError("no such build %d" % number)
+         except EOFError:
+             raise IndexError("corrupted build pickle %d" % number)
+ 
++    def cacheMiss(self, number):
++        # first look in currentBuilds
++        for b in self.currentBuilds:
++            if b.number == number:
++                #return self.touchBuildCache(b)
++                return defer.succeed(b)
++
++        # then fall back to loading it from disk
++        return threads.deferToThread(self.loadBuildFromFile, number)
++
+     def prune(self, events_only=False):
+         # begin by pruning our own events
+         self.events = self.events[-self.eventHorizon:]
+@@ -287,7 +294,7 @@
+                     is_logfile = True
+ 
+             if num is None: continue
+-            if num in self.buildCache: continue
++            if num in self.buildCache.cache: continue
+ 
+             if (is_logfile and num < earliest_log) or num < earliest_build:
+                 pathname = os.path.join(self.basedir, filename)
+@@ -510,7 +517,8 @@
+         assert s.number == self.nextBuildNumber - 1
+         assert s not in self.currentBuilds
+         self.currentBuilds.append(s)
+-        self.touchBuildCache(s)
++        #self.touchBuildCache(s)
++        self.buildCache.put(s.number, s)
+ 
+         # now that the BuildStatus is prepared to answer queries, we can
+         # announce the new build to all our watchers
+@@ -620,7 +628,7 @@
+         # Collect build numbers.
+         # Important: Only grab the *cached* builds numbers to reduce I/O.
+         current_builds = [b.getNumber() for b in self.currentBuilds]
+-        cached_builds = list(set(self.buildCache.keys() + current_builds))
++        cached_builds = list(set(self.buildCache.cache.keys() + current_builds))
+         cached_builds.sort()
+         result['cachedBuilds'] = cached_builds
+         result['currentBuilds'] = current_builds