Darren Foong created GEODE-3306:
-----------------------------------
Summary: Parsing of cache.xml with whitespace fails with Apache
Xerces
Key: GEODE-3306
URL: https://issues.apache.org/jira/browse/GEODE-3306
Project: Geode
Issue Type: Bug
Components: core
Reporter: Darren Foong
Fix For: 1.2.0
I am using Geode 1.2.0 and Apache Xerces 2.11.0 (not the one included in the
Oracle JDK), and I encountered the following error when I tried to
programmatically start a cache:
{noformat}
org.apache.geode.InternalGemFireError: Did not expected a
java.lang.StringBuffer on top of the stack.
Exception in thread "main" org.apache.geode.InternalGemFireError: Did not
expected a java.lang.StringBuffer on top of the stack.
at org.apache.geode.internal.Assert.throwError(Assert.java:94)
at org.apache.geode.internal.Assert.assertTrue(Assert.java:117)
at
org.apache.geode.internal.cache.xmlcache.CacheXmlParser.endRegionAttributes(CacheXmlParser.java:1257)
at
org.apache.geode.internal.cache.xmlcache.CacheXmlParser.endElement(CacheXmlParser.java:2909)
at
org.apache.geode.internal.cache.xmlcache.CacheXmlParser$DefaultHandlerDelegate.endElement(CacheXmlParser.java:3374)
at org.apache.xerces.parsers.AbstractSAXParser.endElement(Unknown
Source)
at
org.apache.xerces.parsers.AbstractXMLDocumentParser.emptyElement(Unknown Source)
at org.apache.xerces.impl.xs.XMLSchemaValidator.emptyElement(Unknown
Source)
at
org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown
Source)
at
org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown
Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown
Source)
at org.apache.xerces.jaxp.SAXParserImpl.parse(Unknown Source)
at javax.xml.parsers.SAXParser.parse(SAXParser.java:195)
at
org.apache.geode.internal.cache.xmlcache.CacheXmlParser.parse(CacheXmlParser.java:224)
at
org.apache.geode.internal.cache.GemFireCacheImpl.loadCacheXml(GemFireCacheImpl.java:4287)
at
org.apache.geode.internal.cache.GemFireCacheImpl.initializeDeclarativeCache(GemFireCacheImpl.java:1390)
at
org.apache.geode.internal.cache.GemFireCacheImpl.initialize(GemFireCacheImpl.java:1195)
at
org.apache.geode.internal.cache.GemFireCacheImpl.basicCreate(GemFireCacheImpl.java:758)
at
org.apache.geode.internal.cache.GemFireCacheImpl.create(GemFireCacheImpl.java:745)
at org.apache.geode.cache.CacheFactory.create(CacheFactory.java:173)
at org.apache.geode.cache.CacheFactory.create(CacheFactory.java:212)
at server.ServerWhitespace.main(ServerWhitespace.java:8)
{noformat}
However, this does not happen when I don't use Apache Xerces, i.e. I rely on
the version in the Oracle JDK (1.8).
After getting the Geode source code and stepping through the parsing using the
Eclipse debugger, I realised that there were unexpected StringBuffers pushed
onto the parse stack, thus causing the problem.
These StringBuffers were created and pushed by the {{characters()}} method
(https://github.com/apache/geode/blob/develop/geode-core/src/main/java/org/apache/geode/internal/cache/xmlcache/CacheXmlParser.java#L3270).
Changing the log level to {{TRACE}} and examining the parse stack showed that
these StringBuffers contained the whitespace (including newlines) between the
XML tags in {{cache.xml}}.
When using the Oracle JDK's version of Xerces, these StringBuffers did not
appear on the parse stack despite the whitespace.
I have a proof of concept on GitHub:
https://github.com/darrenfoong/geode-parser-poc The {{cache.xml}} file without
whitespace between the tags was parsed without errors by both versions of
Xerces.
It could be the case that the JDK Xerces strips out whitespace while Apache
Xerces doesn't; but this could be implemented in {{characters()}} by only
pushing non-whitespace char arrays in the {{else}} block. However, there could
be other XML parsing edge cases that I am unaware of.
There should be others who need Apache Xerces for their projects; a fix would
be appreciated.
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