[8.6.0] Fix two incorrect usages of SkyframeLookupResult
#27973
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All the values have to be checked for nullness individually. Fixes the following two NPEs: 1. bazel-contrib/rules_go#4531 (comment) ``` java.lang.NullPointerException: Cannot invoke "com.google.devtools.build.lib.skyframe.PackageValue.getPackage()" because the return value of "com.google.devtools.build.skyframe.SkyframeLookupResult.getOrThrow(com.google.devtools.build.skyframe.SkyKey, java.lang.Class)" is null at com.google.devtools.build.lib.skyframe.TestExpansionFunction.getPrerequisites(TestExpansionFunction.java:169) at com.google.devtools.build.lib.skyframe.TestExpansionFunction.computeExpandedTests(TestExpansionFunction.java:85) ... ``` 2. bazelbuild#27942 ``` java.lang.NullPointerException at java.base/java.util.stream.ReferencePipeline$3$1.accept(Unknown Source) at java.base/java.util.stream.ReferencePipeline$3$1.accept(Unknown Source) at java.base/java.util.stream.ReferencePipeline$3$1.accept(Unknown Source) at java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining(Unknown Source) at java.base/java.util.stream.AbstractPipeline.copyInto(Unknown Source) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source) at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(Unknown Source) at java.base/java.util.stream.AbstractPipeline.evaluate(Unknown Source) at java.base/java.util.stream.ReferencePipeline.collect(Unknown Source) at com.google.devtools.build.lib.skyframe.DirectoryTreeDigestFunction.getSubDirTreeDigests(DirectoryTreeDigestFunction.java:140) at com.google.devtools.build.lib.skyframe.DirectoryTreeDigestFunction.compute(DirectoryTreeDigestFunction.java:65) ``` Speculative fix for bazelbuild#27942 Closes bazelbuild#27959. PiperOrigin-RevId: 843808256 Change-Id: I012756ec8a641c68bca31fe155d230caa00d8a3f
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Code Review
This pull request correctly fixes two NullPointerExceptions that occurred from incorrect usage of SkyframeLookupResult. The changes ensure that values retrieved from the result are checked for nullness before being used. My review includes one suggestion to improve performance in DirectoryTreeDigestFunction.java by avoiding a double iteration over the collection of keys.
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| if (env.valuesMissing() | ||
| || dirTreeDigestValueKeys.stream().map(result::get).anyMatch(Objects::isNull)) { | ||
| return null; | ||
| } | ||
| return dirTreeDigests; | ||
| return dirTreeDigestValueKeys.stream() | ||
| .map(result::get) | ||
| .map(DirectoryTreeDigestValue.class::cast) | ||
| .map(DirectoryTreeDigestValue::hexDigest) | ||
| .collect(toImmutableList()); |
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While this change correctly fixes the NullPointerException, it iterates over dirTreeDigestValueKeys twice: once to check for nulls and a second time to collect the digests. This could be inefficient for a large number of keys. You can accomplish this more efficiently in a single pass using a traditional for-loop with a builder.
ImmutableList.Builder<String> digests =
ImmutableList.builderWithExpectedSize(dirTreeDigestValueKeys.size());
for (SkyKey key : dirTreeDigestValueKeys) {
var value = (DirectoryTreeDigestValue) result.get(key);
if (value == null) {
// A value is missing. Skyframe will restart.
return null;
}
digests.add(value.hexDigest());
}
return digests.build();
meteorcloudy
approved these changes
Dec 15, 2025
Merged
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bazelbuild:release-8.6.0
with commit Dec 15, 2025
3c27607
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All the values have to be checked for nullness individually.
Fixes the following two NPEs:
Speculative fix for #27942
Closes #27959.
PiperOrigin-RevId: 843808256
Change-Id: I012756ec8a641c68bca31fe155d230caa00d8a3f
Commit 1025821