stevedlawrence commented on a change in pull request #316: Assortment of
changes to improve performance
URL: https://github.com/apache/incubator-daffodil/pull/316#discussion_r370633191
##########
File path:
daffodil-runtime1/src/main/scala/org/apache/daffodil/processors/Evaluatable.scala
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@@ -285,7 +285,17 @@ abstract class Evaluatable[+T <: AnyRef](protected val
ci: DPathCompileInfo, qNa
/**
* Preferred for use in the runtime.
*/
- @inline final def maybeConstant = constValue_.asInstanceOf[Maybe[T]]
+ @inline final def maybeConstant = {
+ // We could just do constValue_.asInstanceOf[Maybe[T]], but the compiled
+ // bytecode ends up allocating a Maybe. Since constant values are accessed
+ // very often, we really want to avoid that overhead. The following gets
+ // rid of those unnecessary allocations.
+ if (constValue_.isDefined) {
+ Maybe[T](constValue_.get.asInstanceOf[T])
Review comment:
Will do. For reference, this was the command:
```bash
find daffodil.git -name '*.class' -exec javap -p -c '{}' \; >
dissasembled.txt
```
From there, it's just a matter of grep, e.g.
```bash
grep -a new disassembled.txt | grep Maybe
```
Note that the -a flag is needed since there's UTF-8 characters or something
that makes grep think the file is binary. Javap is really useful in figuring
out why there are allocations since Scala does so much stuff behind your back.
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