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https://issues.apache.org/jira/browse/SANDBOX-318?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Valery Silaev closed SANDBOX-318.
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> AsmClassTransformer generates wrong bytecode when constructor invocation exist
> ------------------------------------------------------------------------------
>
> Key: SANDBOX-318
> URL: https://issues.apache.org/jira/browse/SANDBOX-318
> Project: Commons Sandbox
> Issue Type: Bug
> Components: Javaflow
> Environment: Sun JDK 1.6.0_16, Windows XP SP3 32bit, ObjectWeb ASM
> 3.1 and 3.2
> Reporter: Valery Silaev
> Priority: Critical
> Attachments: Runner.java, Test.java
>
>
> AsmClassTransformer generates wrong bytecode for the method with
> Continuation.suspend code when there are constructor invocation instructions
> ("new SomeClass()") exist in code.
> The actual errors may be different, but all of them are VerifierErrors.
> Here is an example java.lang.Runnable implementation that explains the
> problem:
> //=========
> package sampleFlow;
> import java.util.Date;
> import java.util.HashMap;
> import java.util.Map;
> import org.apache.commons.javaflow.Continuation;
> public class Runner implements Runnable {
> final Object d = new Date();
> public void run() {
> // No problem for fields
> System.out.println(d);
>
> // No problem for primitives
> for (int i = 0; i < 3; i++)
> System.out.println(i);
>
> // No problem for "externalized" constructor call
> //final Map<String, String> map = newMap();
>
> // But direct constructor invocation always causes an error
> final Map<String, String> map = new HashMap<String, String>();
> map.put("A", "B");
> System.out.println(map);
>
> Continuation.suspend();
> System.out.println("RESUMED, YES!");
> }
> protected Map<String, String> newMap() {
> return new HashMap<String, String>();
> }
> }
> //=========
> Please see comments inside method run() -- when we have direct invocation
> "new HashMap<String, String>()" we got a verifier error:
> org.objectweb.asm.tree.analysis.AnalyzerException: Error at instruction 30:
> Cannot pop operand off an empty stack.
> at org.objectweb.asm.tree.analysis.Analyzer.analyze(Unknown Source)
> at
> org.apache.commons.javaflow.bytecode.transformation.asm.ContinuationMethodAnalyzer$2.analyze(ContinuationMethodAnalyzer.java:124)
> at
> org.apache.commons.javaflow.bytecode.transformation.asm.ContinuationMethodAnalyzer.visitEnd(ContinuationMethodAnalyzer.java:135)
> at org.objectweb.asm.ClassReader.accept(Unknown Source)
> at org.objectweb.asm.ClassReader.accept(Unknown Source)
> However, when we replace constructor call with miscellaneous method call,
> then error goes away.
> Same error may be caused by implicit construction of StringBuilder like for
> expression "abc" + this.d (d is an instance field in example above)
> The problem is not reproducible with BcelClassTransformer, but reproducible
> with all and every way continuable classes are instrumented (ant task,
> ContinuationClassLoader.forceLoadClass, ContinuationClassLoader.loadClass)
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