feat: change engine proxy to use flatbuffer implementation over wasm by chriswk · Pull Request #333 · Unleash/unleash-java-sdk

chriswk · 2025-11-10T09:57:48Z

This patches v11, we should probably also look at updating v10. But for now, this PR allows us to create an RC/beta that can run in our infrastructure to allow us to verify memory usage and performance.

Copilot

Pull Request Overview

This PR updates the SDK to replace WasmResponse with FlatResponse as part of migrating to a newer engine version (yggdrasil-engine 0.4.3). It also includes dependency updates, infrastructure improvements, and example project enhancements.

Renamed WasmResponse to FlatResponse throughout the codebase
Updated dependencies including Spring Boot (3.5.7), Gradle (9.1.0), and various libraries
Added native image example with GraalVM support
Improved test utilities with new ResourceReader class

Reviewed Changes

Copilot reviewed 25 out of 27 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/main/java/io/getunleash/DefaultUnleash.java	Updated to use `FlatResponse` with Optional handling for null safety
src/main/java/io/getunleash/EngineProxyImpl.java	Changed return types from `WasmResponse` to `FlatResponse`
src/main/java/io/getunleash/repository/*.java	Updated method signatures to use `FlatResponse`
src/test/java/io/getunleash/util/ResourceReader.java	New utility class for reading test resources
pom.xml	Updated yggdrasil-engine to 0.4.3, upgraded dependencies, reorganized properties
examples/spring-boot-example/*	Updated Spring Boot to 3.5.7, added dev tools, fixed annotation usage
examples/native-image-example/*	New example demonstrating GraalVM native image support

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sjaanus · 2025-11-10T13:10:26Z

+    FlatResponse<Boolean> isEnabled(String toggleName, UnleashContext context);

-    WasmResponse<VariantDef> getVariant(String toggleName, UnleashContext context);
+    FlatResponse<VariantDef> getVariant(String toggleName, UnleashContext context);


This seems also nullable.

yeah, true, thanks

.NET is expecting these to not be null I believe

sjaanus · 2025-11-10T13:11:23Z

-        WasmResponse<VariantDef> response =
+        FlatResponse<VariantDef> response =
                this.featureRepository.getVariant(toggleName, enhancedContext);
        Optional<VariantDef> variantDef = Optional.ofNullable(response.value);


This can give nullpointer exception, if response is null.

sjaanus · 2025-11-10T14:37:06Z

-        Optional<VariantDef> variantDef = Optional.ofNullable(response.value);
+        Optional<FlatResponse<VariantDef>> response =
+                Optional.ofNullable(this.featureRepository.getVariant(toggleName, enhancedContext));
+        Optional<VariantDef> variantDef = response.map(r -> r.value);


I think now if we call variantDef.get() you might get null as result, but you actually want isPresent to return false?

I think we want Optional<VariantDef> variantDef = response.flatMap(r -> Optional.ofNullable(r.value));

This is what we do in https://github.com/Unleash/unleash-java-sdk/pull/333/files#diff-5209f3f32d148f4e260e39b0166a5cd032fdc210bd83b0859993c254d4325263R119

I agree monadically / if java actually did optionals the expected way, but as I just confirmed with jshell, when you map an option, if your option returns null, you get Optional.empty, not an NPE

jshell> Optional<String> my_present = Optional.of("hello"); my_present ==> Optional[hello] jshell> Optional<String> absent = my_present.map(s -> null) absent ==> Optional.empty

Oh wow, nice!

coveralls · 2025-11-10T17:42:11Z

Pull Request Test Coverage Report for Build 19326878737

Details

11 of 11 (100.0%) changed or added relevant lines in 1 file are covered.
No unchanged relevant lines lost coverage.
Overall coverage increased (+0.2%) to 79.262%

Totals
Change from base Build 18901356217:	0.2%
Covered Lines:	2483
Relevant Lines:	3060

💛 - Coveralls

…spring boot

… in isEnabled call

daveleek · 2025-11-13T14:12:28Z

+                getOrElse("UNLEASH_API_TOKEN",
+                    "*:development.25a06b75248528f8ca93ce179dcdd141aedfb632231e0d21fd8ff349"))
+            .unleashAPI(getOrElse("UNLEASH_API_URL", "https://app.unleash-hosted.com/demo/api"))


Good enough for now I guess, but yeah maybe should've been env arg?

It is an env arg. we just default to one that used to be able to access demo, but since we wipe demo regularly, I'm not worried.

daveleek · 2025-11-13T14:13:04Z

+                getOrElse("UNLEASH_API_TOKEN",
+                    "*:development.25a06b75248528f8ca93ce179dcdd141aedfb632231e0d21fd8ff349"))


daveleek · 2025-11-13T14:13:37Z

+    url: http://localhost:4242/api
+    apiKey: "*:development.da33883b2b2be02c5648ac624a1f50922cbc5893c2e6de5b9f57298d"


this isn't going to work is it?

daveleek

Cool :)

chriswk requested review from Copilot, daveleek and sighphyre November 10, 2025 09:57

chriswk self-assigned this Nov 10, 2025

thomasheartman added this to Issues and PRs Nov 10, 2025

github-project-automation Bot moved this to New in Issues and PRs Nov 10, 2025

Copilot AI reviewed Nov 10, 2025

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chriswk enabled auto-merge (squash) November 10, 2025 12:56

sjaanus reviewed Nov 10, 2025

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chriswk moved this from New to In Progress in Issues and PRs Nov 11, 2025

chriswk added 17 commits November 13, 2025 10:27

added flatbuffer ffi implementation

aa4e719

more work around testing for memory

518fa6a

chore(examples): Added example for native-image

d536391

Updated native example to use 11.2.0-SNAPSHOT

3d439e0

feat(ffiflat): Now uses JNI instead of JNA version of java-engine

19ec8a1

chore: updated spring-boot example to use 11.2.0-SNAPSHOT and newest …

e7ef58f

…spring boot

bump to released version of java-engine

93a6aee

use unleash.version as parameter to jmh

02a0449

chore: removed unnecessary printlns and safely wrapped nullable value…

9120881

… in isEnabled call

fix: revert spotless to 2.46 to keep compatibility with java 11

d4af2d6

fix(build) remove enable-native-access

006a728

fix(test): use toURI instead of toPath to provide platform compat

21ee46b

Optimize imports

4850451

fix: github comments on nullability

1a17900

updated cli-example to have configurable interval

62ab172

added build configuration for java docker container of example

1c3d46d

task: configure log4j2 with json logging

15bc46c

chriswk force-pushed the fix/ffiFlat branch from 0d75fed to 15bc46c Compare November 13, 2025 09:29

daveleek reviewed Nov 13, 2025

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daveleek approved these changes Nov 13, 2025

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chriswk merged commit e92733d into main Nov 13, 2025
9 checks passed

chriswk deleted the fix/ffiFlat branch November 13, 2025 14:15

github-project-automation Bot moved this from In Progress to Done in Issues and PRs Nov 13, 2025

		getOrElse("UNLEASH_API_TOKEN",
		"*:development.25a06b75248528f8ca93ce179dcdd141aedfb632231e0d21fd8ff349"))

		url: http://localhost:4242/api
		apiKey: "*:development.da33883b2b2be02c5648ac624a1f50922cbc5893c2e6de5b9f57298d"

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chriswk commented Nov 10, 2025

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Pull Request Test Coverage Report for Build 19326878737

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coveralls commented Nov 10, 2025 •

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