Problems with DepthFirstAnalysis and the IBM JDK
------------------------------------------------
Key: OPENJPA-304
URL: https://issues.apache.org/jira/browse/OPENJPA-304
Project: OpenJPA
Issue Type: Bug
Components: lib
Affects Versions: 0.9.7
Reporter: Kevin Sutter
Assignee: Kevin Sutter
Fix For: 1.0.0
TestDepthFirstAnalysis was reporting two errors when running with the IBM JDK.
The testcase ran just fine with the Sun JDK. The error conditions were NPE's
in testBackEdges and testForwardEdges:
testBackEdges(org.apache.openjpa.lib.graph.TestDepthFirstAnalysis) Time
elapsed: 0 sec <<< ERROR!
java.lang.NullPointerException
at
org.apache.openjpa.lib.graph.DepthFirstAnalysis.visit(DepthFirstAnalysis.java:97)
at
org.apache.openjpa.lib.graph.DepthFirstAnalysis.<init>(DepthFirstAnalysis.java:74)
at org.apache.openjpa.lib.graph.TestDepthFirstAnalysis.setUpGraph2
(TestDepthFirstAnalysis.java:78)
at
org.apache.openjpa.lib.graph.TestDepthFirstAnalysis.testBackEdges(TestDepthFirstAnalysis.java:105)
:
testForwardEdges(org.apache.openjpa.lib.graph.TestDepthFirstAnalysis) Time
elapsed: 0 sec <<< ERROR!
java.lang.NullPointerException
at
org.apache.openjpa.lib.graph.DepthFirstAnalysis.visit(DepthFirstAnalysis.java:97)
at
org.apache.openjpa.lib.graph.DepthFirstAnalysis.<init>(DepthFirstAnalysis.java
:74)
at
org.apache.openjpa.lib.graph.TestDepthFirstAnalysis.setUpGraph2(TestDepthFirstAnalysis.java:78)
at
org.apache.openjpa.lib.graph.TestDepthFirstAnalysis.testForwardEdges(TestDepthFirstAnalysis.java
:129)
:
Some debugging with the IBM JDK turned up a couple of problems:
1) The code in DepthFirstAnalysis.java and Edges.java was using == for
equality testing instead of .equals(). It turns out that the IBM JDK has an
optimization when using Integer instances as keys to HashMaps and new copies of
the keys are created (vs using the input key objects directly). Thus, the ==
check was not sufficient to do the comparison testing.
2) After performing those updates, there was yet another problem with the
order of the entries returned by the iterator() of the HashMap. By definition,
the
order is not guaranteed with a HashMap implementation. In these particular
failing testcases, the Sun JDK was starting with node 2 via the Iterator, while
the IBM JDK was starting with node 5. By changing the declaration of this
Graph._nodes structure to use a LinkedHashMap (instead of HashMap), we can
reliably determine the order of the iterator. And, now both the Sun and IBM
JDK's produce the same results.
Thanks,
Kevin
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