Fix two incorrect usages of `SkyframeLookupResult` #27959

fmeum · 2025-12-12T13:56:06Z

All the values have to be checked for nullness individually.

Fixes the following two NPEs:

refactor: Remove next batch of WORKSPACE content 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)
...

Crash while DirectoryTreeDigestFunction.getSubDirTreeDigests #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 #27942

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

gemini-code-assist · 2025-12-12T13:56:23Z

Summary of Changes

Hello @fmeum, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses two distinct NullPointerException issues arising from incorrect handling of SkyframeLookupResult in different parts of the codebase. By adding explicit null checks where values from Skyframe lookups might be null, the changes enhance the robustness of the system and prevent crashes related to missing or unavailable Skyframe values, specifically targeting issues identified in TestExpansionFunction and DirectoryTreeDigestFunction.

Highlights

Null Pointer Exception Fix in TestExpansionFunction: Introduced an explicit null check for PackageValue obtained from SkyframeLookupResult.getOrThrow to prevent a NullPointerException when attempting to access its package.
Null Pointer Exception Fix in DirectoryTreeDigestFunction: Added a null check within the stream processing for values retrieved from SkyframeLookupResult.get to prevent NullPointerException during the collection of directory tree digests.

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fmeum · 2025-12-12T13:56:26Z

FYI @sluongng @dzbarsky @Wyverald

fmeum · 2025-12-12T13:56:40Z

@bazel-io fork 9.0.0

fmeum · 2025-12-12T13:56:45Z

@bazel-io fork 8.6.0

gemini-code-assist

Code Review

This pull request correctly fixes two NullPointerExceptions that occurred due to incorrect usage of SkyframeLookupResult. The changes ensure that values retrieved from the result are checked for nullness before being used, which resolves the reported crashes. The fix in TestExpansionFunction.java is solid. For DirectoryTreeDigestFunction.java, while the fix is correct, I've suggested a more efficient implementation to avoid iterating over the collection of keys twice.

gemini-code-assist · 2025-12-12T13:58:44Z

src/main/java/com/google/devtools/build/lib/skyframe/DirectoryTreeDigestFunction.java

+    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());


While this change correctly fixes the NullPointerException, it iterates over dirTreeDigestValueKeys twice (once in anyMatch and again in the final stream). You can achieve the same result more efficiently with a single pass using a traditional for-loop. This avoids the overhead of creating two streams.

if (env.valuesMissing()) { return null; } ImmutableList.Builder<String> digests = ImmutableList.builderWithExpectedSize(dirTreeDigestValueKeys.size()); for (SkyKey key : dirTreeDigestValueKeys) { var value = (DirectoryTreeDigestValue) result.get(key); if (value == null) { return null; } digests.add(value.hexDigest()); } return digests.build();

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

Wyverald · 2025-12-12T22:50:13Z

We might actually need a 8.5.1 for this, as we're now constantly running into this on Bazel's own pre-/postsubmit after 03ee90a.

Alternatively, we can just wait for 9.0.0 to ship (hopefully before EOY)...

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. #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 #27942 Closes #27959. PiperOrigin-RevId: 843808256 Change-Id: I012756ec8a641c68bca31fe155d230caa00d8a3f Commit 1025821 Co-authored-by: Fabian Meumertzheim <fabian@meumertzhe.im>

fmeum · 2025-12-13T07:36:24Z

We should also include #27967 in an 8.5.1 patch release.

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. #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 #27942 Closes #27959. PiperOrigin-RevId: 843808256 Change-Id: I012756ec8a641c68bca31fe155d230caa00d8a3f Commit 1025821 Co-authored-by: Fabian Meumertzheim <fabian@meumertzhe.im>

iancha1992 · 2025-12-15T17:38:12Z

@bazel-io fork 8.5.1

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

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. #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 #27942 Closes #27959. PiperOrigin-RevId: 843808256 Change-Id: I012756ec8a641c68bca31fe155d230caa00d8a3f Commit 1025821 Co-authored-by: Fabian Meumertzheim <fabian@meumertzhe.im>

meteorcloudy · 2025-12-17T09:35:05Z

https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/5143#019b2926-7bd0-4681-9e27-8e904882eab5

With 8.5.1, we get:

(22:00:01) ERROR: /var/lib/buildkite-agent/builds/bk-docker-2nvg/bazel-org-repo-root/bazel/src/test/shell/bazel/list_source_repository.bzl:44:20: An error occurred during the fetch of repository '+_repo_rules3+local_bazel_source_list':
   Traceback (most recent call last):
	File "/var/lib/buildkite-agent/builds/bk-docker-2nvg/bazel-org-repo-root/bazel/src/test/shell/bazel/list_source_repository.bzl", line 44, column 20, in _impl
		rctx.watch_tree(workspace)
Error in watch_tree: com.google.devtools.build.lib.io.InconsistentFilesystemException: Inconsistent filesystem operations. File [/var/lib/buildkite-agent/.cache/bazel/_bazel_buildkite-agent/ebd41e5c8e7ac058026f5f87cd6bfd84]/[execroot/_main/bazel-out/k8-fastbuild/bin/src/java_tools/junitrunner/java/com/google/testing/junit/runner/junit4/libjunit4.jar-0.params.tmp.8588] found in directory, but stat failed The results of the build are not guaranteed to be correct. You should probably run 'bazel clean' and investigate the filesystem inconsistency (likely due to filesystem updates concurrent with the build)

sluongng · 2025-12-17T09:39:32Z

Oh interesting. I suspect we need to exclude the symlinks from the watch (and all others gitignore entries)

fmeum requested a review from justinhorvitz December 12, 2025 13:56

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[9.0.0] Fix two incorrect usages of SkyframeLookupResult #27960

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[8.6.0] Fix two incorrect usages of SkyframeLookupResult #27961

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bazel-io mentioned this pull request Dec 12, 2025

[9.0.0] Fix two incorrect usages of SkyframeLookupResult #27972

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bazel-io mentioned this pull request Dec 12, 2025

[8.6.0] Fix two incorrect usages of SkyframeLookupResult #27973

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Wyverald mentioned this pull request Dec 15, 2025

Bazel presubmit/postsubmit crashes on RBE #27982

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bazel-io mentioned this pull request Dec 15, 2025

[8.5.1] Fix two incorrect usages of SkyframeLookupResult #27992

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bazel-io mentioned this pull request Dec 15, 2025

[8.5.1] Fix two incorrect usages of SkyframeLookupResult #27994

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Fix two incorrect usages of `SkyframeLookupResult` #27959

Fix two incorrect usages of `SkyframeLookupResult` #27959