specify a default num_events value for the waterfall in the master

config file instead of changing a hard coded value, and add a
configurable limit, too

buildbot/status/web/baseweb.py

@@ -398,7 +398,8 @@ class WebStatus(service.MultiService):
     # all the changes).
 
     def __init__(self, http_port=None, distrib_port=None, allowForce=False,
-                 public_html="public_html", site=None, numbuilds=20, auth=None):
+                 public_html="public_html", site=None, numbuilds=20, 
+                 num_events=200, num_event_max=None, auth=None):
         """Run a web server that provides Buildbot status.
 
         @type  http_port: int or L{twisted.application.strports} string
@@ -449,6 +450,14 @@ def __init__(self, http_port=None, distrib_port=None, allowForce=False,
         by passing the equally named argument to constructors of OneLinePerBuildOneBuilder
         and OneLinePerBuild --- and via the UI, by tacking ?numbuilds=xy onto the URL.
 
+        @type num_events: int
+        @param num_events: Defaualt number of events to show in the waterfall.
+
+        @type num_events_max: int
+        @param num_events_max: The maximum number of events that are allowed to be
+        shown in the waterfall.  The default value of C{None} will disable this
+        check
+
         @type auth: a L{status.web.auth.IAuth} or C{None}
         @param auth: an object that performs authentication to restrict access
                      to the C{allowForce} features. Ignored if C{allowForce}
@@ -467,6 +476,10 @@ def __init__(self, http_port=None, distrib_port=None, allowForce=False,
                 distrib_port = "unix:%s" % distrib_port
         self.distrib_port = distrib_port
         self.allowForce = allowForce
+        self.num_events = num_events
+        if num_events_max:
+            assert num_events_max >= num_events
+            self.num_events_max = num_events_max
         self.public_html = public_html
 
         if self.allowForce and auth:
@@ -488,7 +501,8 @@ def __init__(self, http_port=None, distrib_port=None, allowForce=False,
             self.site = server.Site(root)
         self.childrenToBeAdded = {}
 
-        self.setupUsualPages(numbuilds=numbuilds)
+        self.setupUsualPages(numbuilds=numbuilds, num_events=num_events,
+                             num_events_max=num_events_max)
 
         # the following items are accessed by HtmlResource when it renders
         # each page.
@@ -511,9 +525,10 @@ def __init__(self, http_port=None, distrib_port=None, allowForce=False,
             s = strports.service(self.distrib_port, f)
             s.setServiceParent(self)
 
-    def setupUsualPages(self, numbuilds):
+    def setupUsualPages(self, numbuilds, num_events, num_events_max):
         #self.putChild("", IndexOrWaterfallRedirection())
-        self.putChild("waterfall", WaterfallStatusResource())
+        self.putChild("waterfall", WaterfallStatusResource(num_events=num_events,
+                                        num_events_max=num_events_max))
         self.putChild("grid", GridStatusResource())
         self.putChild("console", ConsoleStatusResource())
         self.putChild("tgrid", TransposedGridStatusResource())

buildbot/status/web/waterfall.py

@@ -417,9 +417,11 @@ class WaterfallStatusResource(HtmlResource):
     """This builds the main status page, with the waterfall display, and
     all child pages."""
 
-    def __init__(self, categories=None):
+    def __init__(self, categories=None, num_events=200, num_events_max=None):
         HtmlResource.__init__(self)
         self.categories = categories
+        self.num_events=num_events
+        self.num_events_max=num_events_max
         self.putChild("help", WaterfallHelp(categories))
 
     def getTitle(self, request):
@@ -699,7 +701,11 @@ def buildGrid(self, request, builders):
         else:
             minTime = None
         spanLength = 10  # ten-second chunks
-        maxPageLen = int(request.args.get("num_events", [200])[0])
+        req_events=int(request.args.get("num_events", [self.num_events])[0])
+        if self.num_events_max and req_events > self.num_events_max:
+            maxPageLen = self.num_events_max
+        else:
+            maxPageLen = req_events
 
         # first step is to walk backwards in time, asking each column
         # (commit, all builders) if they have any events there. Build up the