[Zope-Checkins] CVS: Zope/lib/python/Products/SiteErrorLog - SiteErrorLog.py:1.6

[Toby Dickenson]

Update of /cvs-repository/Zope/lib/python/Products/SiteErrorLog
In directory cvs.zope.org:/tmp/cvs-serv24534

Modified Files:
	SiteErrorLog.py 
Log Message:
collector 366; added rate limiting to the 'copy to zlog' option, to prevent flooding

=== Zope/lib/python/Products/SiteErrorLog/SiteErrorLog.py 1.5 => 1.6 ===
 log_to_event_log = 'Log to the Event Log'
 
+# We want to restrict the rate at which errors are sent to the Event Log
+# because we know that these errors can be generated quick enough to
+# flood some zLOG backends. zLOG is used to notify someone of a problem,
+# not to record every instance.
+# This dictionary maps exception name to a value which encodes when we
+# can next send the error with that name into the event log. This dictionary
+# is shared between threads and instances. Concurrent access will not
+# do much harm.
+_rate_restrict_pool = {}
+
+# The number of seconds that must elapse on average between sending two
+# exceptions of the same name into the the Event Log. one per minute. 
+_rate_restrict_period = 60
+
+# The number of exceptions to allow in a burst before the above limit
+# kicks in. We allow five exceptions, before limiting them to one per
+# minute.
+_rate_restrict_burst = 5
 
 _www = os.path.join(os.path.dirname(__file__), 'www')
 
@@ -168,9 +186,17 @@
                     error=sys.exc_info())
             else:
                 if self.copy_to_zlog:
-                    LOG('SiteError', ERROR, str(url), error=info)
+                    self._do_copy_to_zlog(now,strtype,str(url),info)
         finally:
             info = None
+
+    def _do_copy_to_zlog(self,now,strtype,url,info):
+        when = _rate_restrict_pool.get(strtype,0)
+        if now>when:
+            next_when = max(when, now-_rate_restrict_burst*_rate_restrict_period)
+            next_when += _rate_restrict_period
+            _rate_restrict_pool[strtype] = next_when
+            LOG('SiteError', ERROR, str(url), error=info)
 
     security.declareProtected(use_error_logging, 'getProperties')
     def getProperties(self):