[DAFFODIL-2619] Add InfosetInputter with minimal overhead

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.3.0
• Component/s: Performance
• Assignee: Steve Lawrence
• Reporter: Steve Lawrence
• Created: 05/Jan/22 15:17
• Updated: 12/Jan/22 19:02
• Resolved: 12/Jan/22 14:26

Description

When unparsing, some amount of performance can be attributed to parsing/traversing the infoset representation (e.g. text, Scala, JDOM) and converting it to the infoset events that Daffodil requires. This is done via an InfosetInputter. Because an InfosetInputter is required during unparsing (unlike parse which can have a null InfosetOutputter) it is difficult to determine how much overhead comes from the InfosetInputter and how much comes from the actual unpasing operations.

One potential option to get a better pictures of raw unparse speed vs InfosetInputter overhead is to create a new InfosetInputter that uses a pre-created array of events that are as close as possible to what Daffodil expects. This way, the overhead of creating the event array can occur outside any measured unparser code, and the overhead of the InfosetInputter that does occur inside measured code is quite small--just the amount to index into this array and return the event information.