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<title>[9507] CalendarServer/trunk/twistedcaldav/directory/directory.py</title>
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<dt>Revision</dt> <dd><a href="http://trac.macosforge.org/projects/calendarserver/changeset/9507">9507</a></dd>
<dt>Author</dt> <dd>sagen@apple.com</dd>
<dt>Date</dt> <dd>2012-07-30 10:23:16 -0700 (Mon, 30 Jul 2012)</dd>
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<h3>Log Message</h3>
<pre>Perform a group cacher update when that sidecar receives SIGHUP.</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#CalendarServertrunktwistedcaldavdirectorydirectorypy">CalendarServer/trunk/twistedcaldav/directory/directory.py</a></li>
</ul>

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<div id="patch">
<h3>Diff</h3>
<a id="CalendarServertrunktwistedcaldavdirectorydirectorypy"></a>
<div class="modfile"><h4>Modified: CalendarServer/trunk/twistedcaldav/directory/directory.py (9506 => 9507)</h4>
<pre class="diff"><span>
<span class="info">--- CalendarServer/trunk/twistedcaldav/directory/directory.py        2012-07-30 17:22:26 UTC (rev 9506)
+++ CalendarServer/trunk/twistedcaldav/directory/directory.py        2012-07-30 17:23:16 UTC (rev 9507)
</span><span class="lines">@@ -30,6 +30,7 @@
</span><span class="cx"> 
</span><span class="cx"> import datetime
</span><span class="cx"> import os
</span><ins>+import signal
</ins><span class="cx"> import sys
</span><span class="cx"> import types
</span><span class="cx"> import pwd, grp
</span><span class="lines">@@ -851,36 +852,73 @@
</span><span class="cx">         if reactor is None:
</span><span class="cx">             from twisted.internet import reactor
</span><span class="cx">         self.reactor = reactor
</span><ins>+
</ins><span class="cx">         self.updateSeconds = updateSeconds
</span><span class="cx">         self.nextUpdate = None
</span><ins>+        self.updateInProgress = False
+        self.updateAwaiting = False
+
</ins><span class="cx">         if updateMethod:
</span><span class="cx">             self.updateMethod = updateMethod
</span><span class="cx">         else:
</span><span class="cx">             self.updateMethod = self.updater.updateCache
</span><span class="cx"> 
</span><span class="cx">     def startService(self):
</span><ins>+        self.previousHandler = signal.signal(signal.SIGHUP, self.sighupHandler)
</ins><span class="cx">         self.log_warn(&quot;Starting group membership cacher service&quot;)
</span><span class="cx">         service.Service.startService(self)
</span><span class="cx">         return self.update()
</span><span class="cx"> 
</span><del>-    @inlineCallbacks
-    def update(self):
-        self.nextUpdate = None
-        try:
-            yield self.updateMethod()
-        finally:
-            self.log_info(&quot;Scheduling next group membership update&quot;)
-            self.nextUpdate = self.reactor.callLater(self.updateSeconds,
-                self.update)
</del><ins>+    def sighupHandler(self, num, frame):
+        self.reactor.callFromThread(self.update)
</ins><span class="cx"> 
</span><span class="cx">     def stopService(self):
</span><ins>+        signal.signal(signal.SIGHUP, self.previousHandler)
</ins><span class="cx">         self.log_warn(&quot;Stopping group membership cacher service&quot;)
</span><span class="cx">         service.Service.stopService(self)
</span><span class="cx">         if self.nextUpdate is not None:
</span><span class="cx">             self.nextUpdate.cancel()
</span><ins>+            self.nextUpdate = None
</ins><span class="cx"> 
</span><ins>+    @inlineCallbacks
+    def update(self):
+        &quot;&quot;&quot;
+        A wrapper around updateCache, this method manages the scheduling of the
+        subsequent update, as well as prevents multiple updates from running
+        simultaneously, which could otherwise happen because SIGHUP now triggers
+        an update on demand.  If update is called while an update is in progress,
+        as soon as the first update is finished a new one is started.  Otherwise,
+        when an update finishes and there is not another one waiting, the next
+        update is scheduled for updateSeconds in the future.
</ins><span class="cx"> 
</span><ins>+        @return: True if an update was already in progress, False otherwise
+        @rtype: C{bool}
+        &quot;&quot;&quot;
</ins><span class="cx"> 
</span><ins>+        self.log_debug(&quot;Group membership update called&quot;)
+
+        # A call to update while an update is in progress sets the updateAwaiting flag
+        # so that an update happens again right after the current one is complete.
+        if self.updateInProgress:
+            self.updateAwaiting = True
+            returnValue(True)
+
+        self.nextUpdate = None
+        self.updateInProgress = True
+        self.updateAwaiting = False
+        try:
+            yield self.updateMethod()
+        finally:
+            self.updateInProgress = False
+            if self.updateAwaiting:
+                self.log_info(&quot;Performing group membership update&quot;)
+                yield self.update()
+            else:
+                self.log_info(&quot;Scheduling next group membership update&quot;)
+                self.nextUpdate = self.reactor.callLater(self.updateSeconds,
+                    self.update)
+        returnValue(False)
+
</ins><span class="cx"> class GroupMembershipCacherServiceMaker(LoggingMixIn):
</span><span class="cx">     &quot;&quot;&quot;
</span><span class="cx">     Configures and returns a GroupMembershipCacherService
</span></span></pre>
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