[SCXML-61] Infinite loop if an Invoker fires the done event in invoke method

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.6
• Fix Version/s: 0.7

Environment

all platforms

• Assignee: Unassigned
• Reporter: Andy Bailey
• Created: 19/Oct/07 18:36
• Updated: 03/Jan/08 19:46
• Resolved: 04/Dec/07 23:18

Description

With the following code

public class HazInvoker implements Invoker
{
@Override public void invoke(String source, Map parameters) throws InvokerException
{
System.out.println("Invoker invoke source: "source" params: "+parameters);
SCXMLExecutor executor = scInstance.getExecutor();
TriggerEvent event=new TriggerEvent(parentStateId+".invoker.done", TriggerEvent.SIGNAL_EVENT);

//new AsyncTrigger(executor, event);
try

{ executor.triggerEvent(event); }

catch (ModelException ex)

{ ex.printStackTrace(); }

}

Exception in thread "main" java.lang.StackOverflowError
at java.util.Vector.addElement(Vector.java:573)
at java.util.Stack.push(Stack.java:50)
...
at org.apache.commons.scxml.semantics.SCXMLSemanticsImpl.initiateInvokes(SCXMLSemanticsImpl.java:824)
at org.apache.commons.scxml.SCXMLExecutor.triggerEvents(SCXMLExecutor.java:142)
at org.apache.commons.scxml.SCXMLExecutor.triggerEvent(SCXMLExecutor.java:160)
at com.hazlorealidad.fsm.HazInvoker.invoke(HazInvoker.java:37)
at org.apache.commons.scxml.semantics.SCXMLSemanticsImpl.initiateInvokes(SCXMLSemanticsImpl.java:824)
at org.apache.commons.scxml.SCXMLExecutor.triggerEvents(SCXMLExecutor.java:142)
at org.apache.commons.scxml.SCXMLExecutor.triggerEvent(SCXMLExecutor.java:160)
at com.hazlorealidad.fsm.HazInvoker.invoke(HazInvoker.java:37)

The fix is to use the AsyncTrigger but the class is package private, I would be good to change it to public and document the way to write a synchronous invoker in the invoke method.

Something like:
"If the Invoker completes its invocation in the invoke method it should signal the completion of the task using an AsyncTrigger, in order to avoid a stack overflow"

Or maybe there is another solution which would allow the event to be fired in the invoke method.

Also it would be good to avoid the creation of a thread just for that, maybe an invokeLater method in the executor, like the swing dispatch loop.