Deprecate second parameter of SourceSection.createUnavailable()

[pniederw]

O.17 has deprecated SourceSection.getIdentifier(). Presumably this means that the second parameter to SourceSection.createUnavailable() should also be deprecated, as all it does it to set identifier.

[chumer]

Thanks for this suggestion. Its already on the way. We are , very likely, going to deprecate SourceSection#createUnavailalble and replace it with Source#createUnavailableSection() including a SourceSection#isUnavailable().

We are also going to shrink SourceSection to just charIndex with length. lines and columns indices are going to be computed lazily. All of this we are doing to minimize the footprint of source sections.

BTW.: You can also compute source sections lazily in Node#getSourceSection() by storing the indices in the Node directly and the Source object in the RootNode.

[smarr]

@chumer: If I remember correctly, the instrumentation API checks for source sections to be available as a precondition for checking tags. Is that going to be removed as part of the change you mentioned?

[chumer]

No not due to this change. Source sections are only queried if instrumentations are actually installed (does not yet apply for root nodes, but that will change). We optimize for the fast case where we only execute but not instrument the application.

The source section restriction might change, as soon as we add support for dynamic changes in tags. Its on the TODO list, but not yet appeared on top.

[smarr]

Sorry for getting off-topic for this issue here:

@chumer ok, but this means instrumentation usage force lazy source section creation? That's how I'd read https://github.com/graalvm/truffle/blob/master/truffle/com.oracle.truffle.api.instrumentation/src/com/oracle/truffle/api/instrumentation/InstrumentationHandler.java#L908

[chumer]

Yes in this case we would need to request the source section atm. We could remove the call to #getSourceSection if we lift the source section restriction, which i am not yet sure if its going to happen.

[mlvdv]

Source sections are only queried if instrumentations are actually installed

Won't there be a need for source information when a language implementation prints a stack trace?

Also: some languages offer features that depend on instrumentation, where the line between language and tool support is blurry.

[chumer]

Michael is right that the source information might also be materialized when the stack trace is printed. It still can be deferred until when it is actually printed.

The discussed method SourceSection#createUnavailable was already removed from the API.