[JXPATH-166] JXPathContextReferenceImpl.addNodePointerFactory not working anymore

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Nightly Builds
• Fix Version/s: 1.4, Nightly Builds
• Assignee: Gary D. Gregory
• Reporter: Michele Vivoda
• Created: 04/Feb/14 05:04
• Updated: 06/Feb/14 19:22
• Resolved: 04/Feb/14 16:40

Description

I tried the following in a single test run in isolation:

JXPathContextReferenceImpl.addNodePointerFactory(new ContainerPointerFactory());

and got ExceptionInInitializer, I see a refactoring for JXPathContext done by ggregory in last (recent) revision 1523175. Reverting to previous 1234255 fixes the issue.

The refactoring contains some static-init code in JXPathContext that creates an instance of a subclass of JXPathContext itself... seems to trigger one of the rare occasions in which a static final field might be null, as happens then in a JXPathContextReferenceImpl constructor where final field nodeFactories is null. My understanding is this: a call to any static method of JXPathContextReferenceImpl triggers load of JXPathContext class that executes static initialization code that creates a new JXPathContext that in turn is an other JXPathContextReferenceImpl with static final field null since the static initializer of its super class must still terminate. See something similar in http://stackoverflow.com/a/2547638/1536382 and http://stackoverflow.com/questions/2547713/why-static-fields-are-not-initialized-in-time

My fix is either to restore the volatile lazy initializaton just for compilationContext or, perhaps (not sure), just create a new context each time in the compile(xpath) static method.

java.lang.ExceptionInInitializerError
	at org.apache.commons.jxpath.ri.AddNodePointerFactoryTest.testAddFactory(AddNodePointerFactoryTest.java:32)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at junit.framework.TestCase.runTest(TestCase.java:154)
	at junit.framework.TestCase.runBare(TestCase.java:127)
	at junit.framework.TestResult$1.protect(TestResult.java:106)
	at junit.framework.TestResult.runProtected(TestResult.java:124)
	at junit.framework.TestResult.run(TestResult.java:109)
	at junit.framework.TestCase.run(TestCase.java:118)
	at junit.framework.TestSuite.runTest(TestSuite.java:208)
	at junit.framework.TestSuite.run(TestSuite.java:203)
	at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:130)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.NullPointerException
	at org.apache.commons.jxpath.ri.JXPathContextReferenceImpl.<init>(JXPathContextReferenceImpl.java:191)
	at org.apache.commons.jxpath.ri.JXPathContextReferenceImpl.<init>(JXPathContextReferenceImpl.java:178)
	at org.apache.commons.jxpath.ri.JXPathContextFactoryReferenceImpl.newContext(JXPathContextFactoryReferenceImpl.java:39)
	at org.apache.commons.jxpath.JXPathContext.newContext(JXPathContext.java:425)
	at org.apache.commons.jxpath.JXPathContext.<clinit>(JXPathContext.java:389)
	... 19 more

Issue Links

• relates to: JXPATH-162 Concurrency problem for JXPathContextFactory.factoryImplName static field