[DAFFODIL-2624] cannot use trace when doing streaming parse calls

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.7.0, 3.2.1
• Fix Version/s: 3.5.0
• Component/s: Back End, Debugger
• Labels: Beginner
• Assignee: Mike McGann
• Reporter: Mike Beckerle
• Created: 13/Jan/22 13:32
• Updated: 22/Feb/23 17:36
• Resolved: 01/Feb/23 16:03

Description

I am using SAPI and writing a streaming message parser. It calls the dp.parse repeatedly to parse the data, grabbing one message at a time from the data stream.

I need to enable tracing so I can see why a parse fails on the 4th message.

But this does not work:

dp = pf.onPath("/")
.withValidationMode(ValidationMode.Off)
.withDebuggerRunner(new TraceDebuggerRunner())
.withDebugging(true)

Each call to parse calls notifyDebugging, which calls setDebugging, which checks that the position of the data input stream is bitPos0b == 0. But in a streaming situation, the bitPos0b won't be zero except when parsing at the start of the stream.

Backtrace:

java.lang.IllegalStateException: Must call before any access to data

	at org.apache.daffodil.io.DataInputStreamImplMixin.setDebugging(DataInputStreamImplMixin.scala:28)
	at org.apache.daffodil.io.DataInputStreamImplMixin.setDebugging$(DataInputStreamImplMixin.scala:27)
	at org.apache.daffodil.io.InputSourceDataInputStream.setDebugging(InputSourceDataInputStream.scala:786)
	at org.apache.daffodil.processors.parsers.PState.notifyDebugging(PState.scala:452)
	at org.apache.daffodil.processors.DataProcessor.parse(DataProcessor.scala:444)
	at org.apache.daffodil.sapi.DataProcessor.parse(Daffodil.scala:747)
	at com.owlcyberdefense.p8.MessageParser.parse(MessageParser.scala:66)

It is also questionable if this Java IllegalStateException should be getting thrown all the way to top level here. Since this is SAPI, this is probably Ok, but I would have expected Daffodil to issue an invariant failed here. This bug is an internal Daffodil issue, and not something SAPI uses should be having to think about catching.