On Tue, 2008-04-22 at 07:59 -0600, Matt Ryan wrote:
> On Tue, 2008-04-22 at 05:27 -0500, Carlo Marcelo Arenas Belon wrote:
> > On Mon, Apr 21, 2008 at 11:48:35AM -0600, Matt Ryan wrote:
> > >
> > > Attached is a patch for this bug. The problem was that with no data
> > > sources providing data to gmetad (since the gmond used as a cluster
> > > collector is down) the internal data structure was empty, and the code
> > > was trying to navigate an empty data structure, hence the 'NoneType'
> > > exception.
> > >
> > > The patch checks for that and does not try to navigate the data
> > > structure if the root node is None. This results in an empty XML
> > > document - the DTD is printed but no other information. Is that
> > > behavior correct?
> >
> > no, an XML with no body is invalid
> >
> > > If not, let me know what the correct behavior should
> > > be on the XML port if there is no data being collected, and I will
> > > revise.
> >
> > stable gmetad returns an XML with an empty GRID (which I suspect is not
> > correct either) but that the web frontend relies on.
> >
> > <GANGLIA_XML VERSION="3.0.7" SOURCE="gmetad">
> > <GRID NAME="unspecified" AUTHORITY="http://dell/ganglia/";
> > LOCALTIME="1208858522">
> > </GRID>
> > </GANGLIA_XML>
> >
> > an empty GANGLIA_XML (no GRID) makes more sense and is valid, but might
> > break
> > the frontend, and so will require further patches
>
>
> Thanks for the clarification, will submit another patch today
> (hopefully) to fix.
Patch attached to fix the XML output when no data is being collected.
--- gmetad_gmondReader.py 2008-04-22 11:34:11.000000000 -0600
+++ gmetad_gmondReader.py.new 2008-04-22 09:00:15.000000000 -0600
@@ -4,7 +4,7 @@
import time
import logging
-from gmetad_config import GmetadConfig
+from gmetad_config import GmetadConfig, getConfig
from gmetad_random import getRandomInterval
from gmetad_data import DataStore, Element
@@ -19,9 +19,10 @@
e = Element(tag, attrs)
if 'GANGLIA_XML' == tag:
ds.lock.acquire()
- self._elemStack.append(ds.setNode(e))
+ self._elemStack.append(ds.getNode()) # Fetch the root node. It
has already been set into the tree.
self._elemStackLen += 1
- cfg = GmetadConfig()
+ cfg = getConfig()
+ # We'll go ahead and update any existing GRID tag with a new one
(new time) even if one already exists.
e = Element('GRID', {'NAME':cfg[GmetadConfig.GRIDNAME],
'AUTHORITY':cfg[GmetadConfig.AUTHORITY], 'LOCALTIME':'%d' % time.time()})
self._elemStack.append(ds.setNode(e,
self._elemStack[self._elemStackLen-1]))
self._elemStackLen += 1
--- gmetad_data.py 2008-04-22 11:34:11.000000000 -0600
+++ gmetad_data.py.new 2008-04-22 08:57:58.000000000 -0600
@@ -1,5 +1,8 @@
import thread
import logging
+import time
+
+from gmetad_config import getConfig, GmetadConfig
class DataStore:
_shared_state = {}
@@ -10,7 +13,16 @@
self.__dict__ = DataStore._shared_state
if not DataStore._initialized:
self.lock = thread.allocate_lock()
+ self.lock.acquire()
self.rootElement = None
+ # Initialize the data store with the GANGLIA_XML and GRID tags.
+ # Data store should never be completely empty. Even if there are
+ # no reporting data sources the web front end depends on having
+ # at least a GANGLIA_XML tag and a nested GRID tag.
+ self.setNode(Element('GANGLIA_XML', {}))
+ cfg = getConfig()
+ self.setNode(Element('GRID', {'NAME':cfg[GmetadConfig.GRIDNAME],
'AUTHORITY':cfg[GmetadConfig.AUTHORITY], 'LOCALTIME':'%d' % time.time()}),
self.rootElement)
+ self.lock.release()
DataStore._initialized = True
def setNode(self, node, parent=None):
@@ -22,7 +34,9 @@
parent[str(node)] = node
return parent[str(node)]
- def getNode(self, ancestry):
+ def getNode(self, ancestry=[]):
+ if not len(ancestry):
+ return self.rootElement
node = None
while ancestry:
nodeId = ancestry.pop(0)
--- gmetad_xmlWriter.py 2008-04-22 11:34:11.000000000 -0600
+++ gmetad_xmlWriter.py.new 2008-04-22 08:27:37.000000000 -0600
@@ -118,6 +118,8 @@
def _getXmlImpl(self, element, filterList=None, queryargs=None):
rbuf = '<%s' % element.id
+ if 'GRID' == element.id:
+ element.localtime = '%d' % time.time()
foundName = False
try:
rbuf += ' NAME="%s"' % element.name
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