stevedlawrence commented on a change in pull request #419:
URL: https://github.com/apache/incubator-daffodil/pull/419#discussion_r488066492
##########
File path:
daffodil-runtime1-unparser/src/main/scala/org/apache/daffodil/processors/unparsers/ElementUnparser.scala
##########
@@ -477,7 +477,7 @@ sealed trait RegularElementUnparserStartEndStrategy
}
val cur = state.currentInfosetNode
if (cur.isComplex)
- cur.asComplex.setFinal()
+ cur.isFinal = true
Review comment:
I think it's actually both a mixture of removeing the trait, and making
things publicly modifable. For example, with a trait we get something like this:
```
public class WithFinalTrait implements Finalizable {
private boolean Finalizable$$_isFinal;
public void Finalizable$$_isFinal_$eq(boolean);
Code:
0: aload_0
1: iload_1
2: putfield #15 // Field Finalizable$$_isFinal:Z
5: return
public void setFinal();
Code:
0: aload_0
1: invokestatic #27 // Method
Finalizable$class.setFinal:(LFinalizable;)V
4: return
}
public abstract class Finalizable$class {
public static void setFinal(Finalizable);
Code:
0: aload_0
1: iconst_1
2: invokeinterface #13, 2 // InterfaceMethod
Finalizable.Finalizable$$_isFinal_$eq:(Z)V
7: return
}
```
So to set the flag we first call setFinal, which calls the static setFinal
method on Finalizable, which then calls \_isFinal_$eq, which finaly sets the
variable to set the value. So three function calls: setFinal, static setFinal,
and isFinal_$eq.
Without the trait, but with private _isFinal, the bytecode is this:
public class WithOutFinalTrait {
private boolean _isFinal;
private void _isFinal_$eq(boolean);
Code:
0: aload_0
1: iload_1
2: putfield #13 // Field _isFinal:Z
5: return
public void setFinal();
Code:
0: aload_0
1: iconst_1
2: invokespecial #22 // Method _isFinal_$eq:(Z)V
5: return
}
So a call to setFinal directly calls _isFinal_$eq to set the variable. So we
remove the one static setFinal call.
With a public final flag and direct modification, the bytecode looks like
this:
public class PublicIsFinal {
private boolean _isFinal;
public boolean _isFinal();
Code:
0: aload_0
1: getfield #13 // Field _isFinal:Z
4: ireturn
public void _isFinal_$eq(boolean);
Code:
0: aload_0
1: iload_1
2: putfield #13 // Field _isFinal:Z
5: return
}
So _isFinal_$eq is called directly which modifies the field directly. So now
we're down to a single function call.
So we go from three functions calls with a trait, to one function call with
public member. This feels like it shouldn't make that much of a difference, but
it definitely did. It wasn't huge, and I'm not sure I would reccommend we do
this everywhere because it does make readability/reusability more difficult,
but in performance critical situations, avoiding traits and private vars seems
to help a bit.
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