tree 844ac0c7b2f5ef8f68e75c29f3c31cdb6e60852b
parent 6266229e4a4e4cc7f096a2a087fe691fdc2743a7
author Mark Schaller <mschaller@google.com> 1445449671 +0000
committer Kristina Chodorow <kchodorow@google.com> 1445526924 +0000

Retain first error message during transitive traversal

Previously, a TransitiveTraversalFunction computed a value that
contained an exception only if the exception resulted from a failure
to load the function's immediate target. If the target had transitive
dependencies on other targets, those other targets would be loaded, but
any errors resulting from loading those targets would not be retained.

SkyQueryEnvironment impromperly used a SkyFrame mechanism (which was
solely intended to ensure equivalent semantics between keep-going and
no-keep-going evaluations) to discover errors in the set of transitive
children of TransitiveTraversal nodes.

In order to transition SkyQueryEnvironment away from that mechanism,
this CL changes TransitiveTraversalFunction to remember the first error
message encountered while loading its target and its transitive
dependencies.

By remembering just the error message as a string, and not the full
exception object, this also helps TransitiveTraversalValue have more
consistent equality semantics for change-pruning.

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MOS_MIGRATED_REVID=105977182