Cache Me If You Can - Speaker Deck

Cache Me If You Can

by RyuNen344

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Cache Me If You Can 2025.09.12 DroidKaigi 2025 RyuNen344

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Cache Me If You Can 2025.09.12 DroidKaigi 2025 RyuNen344 🐘

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Materials

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Ice Break

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͜Μͳܦݧ͋Γ·ͤΜ͔

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ϚϧνϞδϡʔϧͳͷʹϏϧυ͕஗ ͍ɾɾɾɾ Cache͕ޮ͍ͯͳͦ͞͏ɾɾɾ

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Android Gradle PluginΛ্͛ͨΒ Ϗϧυ͕յΕͨ

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ΧελϜλεΫͷCache͕ޮ͔ͳ͍

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GradleΑ͘Θ͔Βͳ͍ɾɾɾ

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Agendas 1. Today's Goals 2. Why Gradle? How the Android Gradle Plugin works? 3. Lifecycle and Lifecycle-aware, everywhere 4. Cache of Gradle 5. Faster, Faster, Faster 6. Key Takeaways

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Today’s Goal • Understands basic concepts of Gradle • Taming Android Gradle Plugin → The ABCs of Faster Gradle Builds

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⚠ Caution ⚠ • ίϯηϓτɾߟ͑ํ͕ϝΠϯ • Ϗϧυ͕N෼୹͘ͳͬͨɾNˋߴ଎Խͨ͠ͳͲ͸φγ • GradleɾAndroid Gradle Pluginͷ͓࡞๏ʹ஫ྗ

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Why Gradle?

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Why Gradle? • Project and Task • Gradle can do anything • Easy to cache

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Project and Task

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Project and Task ./gradlew :sub-project-B:Task c Task c <- Task b <- Task 1

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Project and Task • Extension as Gradle Plugin • Several Language Support by Of fi cial Gradle Plugin • C++, Swift and multiple JVM based languages C++

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Gradle can do anything

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Easy to cache • Gradle watches Task inputs/outputs • Developer just de fi ne deterministic input and Gradle Task action

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How the Android Gradle Plugin works?

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How AGP? :app:assembleDebug +--- :app:mergeDebugNativeDebugMetadata | \--- :app:preDebugBuild | \--- :app:preBuild \--- :app:packageDebug +--- :app:compileDebugJavaWithJavac +--- :app:compressDebugAssets +--- :app:l8DexDesugarLibDebug +--- :app:mergeDebugAssets * +--- :app:mergeDebugJavaResource +--- :app:mergeExtDexDebug +--- :app:mergeLibDexDebug +--- :app:mergeProjectDexDebug +--- :app:preDebugBuild * +--- :app:processDebugManifestForPackage +--- :app:processDebugResources * +--- :app:stripDebugDebugSymbols +--- :app:validateSigningDebug +--- :app:writeDebugAppMetadata \--- :app:writeDebugSigningConfigVersions • Assemble task depends on many tasks

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Lifecycle and Lifecycle-aware, everywhere Gradle has a lifecycle

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Lifecycle and Lifecycle-aware, everywhere • Gradle has a lifecycle

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Initialization Phase • Read settings.gradle and recognize project structure • Specify dependency resolution strategies • Apply settings plugin

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Con fi guration Phase • Read project’s build.gradle • Apply plugin to project • plugin creates con fi guration and tasks • Resolve dependencies • Graph resolution phase • Artifact resolution phase • Execute build scripts

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Execution Phase • Execute tasks • Determine which tasks to execute by the task execution graphs • UP-TO-DATE and FROM-CACHE mean that Gradle has skipped a task by using incremental builds or the build cache

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Also, AGP has a lifecycle AGP's Lifecycle

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AGP's Lifecycle • Key points to understand AGP's Lifecycle

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AGP's Lifecycle

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AGP's Lifecycle • In old Variant API could make a variant disabled after creation • This can break the Task Graph(DAG) • It’s not good for Build Cache(even Con fi guration Cache)

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AGP's Lifecycle

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Lifecycle and Lifecycle-aware, everywhere

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Wrap-up Part 1 • Gradle has a lifecycle • Gradle manages task dependencies and forms a DAG • Gradle reuses task results based on task input/output • Android Gradle Plugin also has a lifecycle • Recent API changes in AGP are to conform to Gradle's lifecycle • Old Variant API is scheduled to be deprecated in AGP 9.0.0, removed in 10.0.0, so it's recommended to migrate to the new API now

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Before We Get to the Cache of Gradle • Idempotence • same input must produce the same output • Performance • appropriate granularity of cache makes high cache hit rate • cache hit is faster than re-execution

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Cache of Gradle

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Cache of Gradle : UP-TO-DATE Incremental build: `UP-TO-DATE`

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Cache of Gradle : UP-TO-DATE

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Cache of Gradle : UP-TO-DATE

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Cache of Gradle : FROM-CACHE

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Cache of Gradle : FROM-CACHE • Based on: • Hash of the task implementation class • All declared inputs • Task Identi fi er • Normalized content hash of fi le inputs used as fi ngerprint • build script is also included in key calculations (e.g. `doFirst`, `doLast`) • Env and System Props will not include unless explicitly declared as input

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Cache of Gradle : Reusing con fi guration cache

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Cache of Gradle : Reusing con fi guration cache When hit con fi skip con fi Skip

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Cache of Gradle : Reusing con fi guration cache • Based on: • GRADLE_USER_HOME • init script • included build scripts • Custom Value Source • System Property and environment • etc… • Requirements: • implements java.io.Serializable

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Wrap-up Part 2 • Incremental build and Build cache • re-use task results based on task input/output • Con fi guration cache • re-use task graph based on con fi guration inputs • Gradle uses different scopes and targets of cache to speed up builds in multiple ways • Con fi guration Cache became the preferred execution mode • Update your API to prevent issues, same as AndroidComponents API

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Faster, faster, faster

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Faster, faster, faster • Make input/output/con fi gurations more deterministic • Optimize project structure

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Faster, faster, faster • First of all, enabling cache features

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Make input/output more deterministic • Make input/output/con fi gurations more deterministic • Optimize project structure

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Make input/output more deterministic • De fi ne @Input and @Output • To enable incremental builds, de fi ne an output property even for tasks that don’t have output • Use Gradle Provider or Property API, instead of Primitive class

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Make input/output more deterministic • When inputs have changed, outputs must change • Avoid using non-declared inputs (Do not use Env or system prop inside TaskAction) •Annotate with @CacheableTask

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Make input/output more deterministic • Avoid using random value as inputs • Use abstracted fi le paths so that the cache does not depend on the environment • Do not edit task output in build script

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Make input/output more deterministic https://docs.gradle.org/current/userguide/incremental_build.html#sec:task_input_output_annotations

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Make con fi guration more deterministic • Can't build project, after adding `org.gradle.con fi guration- cache=true` 😇

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Make con fi guration more deterministic • Do not use àfterEvaluate` block • àfterEvaluate` block executes after con fi guration phase • àfterEvaluate` can break con fi guration phase result

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Make con fi guration more deterministic • Do not touch non- serializable objects in execution time

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Make con fi guration more deterministic • Use `ProjectLayout` or `BuildLayout` API to access fi les instead of `project` • Use injected `{FileSystem| Archive|Exec}`Operations to access fi les instead of `project`

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Make con fi guration more deterministic • Use `ProviderFactory` API to access environment variables, system properties, external process results instead of `System` or direct execution

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Make con fi gurations more deterministic https://docs.gradle.org/current/userguide/ con fi guration_cache_requirements.html#con fi g_cache:requirements:use_project_during_execution

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Use AndroidComponents API • Use AndroidComponents API for deterministic con fi guration

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Use AndroidComponents API • AndroidComponents API enables correct integration into the build process

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Use Android Components API https://github.com/android/gradle-recipes

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Optimize project structure • Android app developer needs fast build 1. Adoption of Jetpack Compose 2. Multi-module as a prerequisite

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Optimize project structure 1.Remove redundant Gradle plugin from sub-project 2.Remove redundant dependency (library or project) 3.Do not con fi gure build variant/project fl avor on library module, use DI

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Optimize project structure

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Optimize project structure Improve cache hit rate & Narrow re-compile scope

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Optimize project structure

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Optimize project structure

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Optimize project structure

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Use Build Scan® • Gradle Knows Gradle Better Than You Know about Gradle • Visualize parallelism on Web UI

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Use Develocity® Plugin • You can visualize without metadata publication • Visualize parallelism on IntelliJ and Android Studio

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Key Takeaways • Gradle has a lifecycle, AGP also has a lifecycle • Gradle has different scopes and targets of cache to speed up builds in multiple ways • Make input/output/con fi gurations more deterministic • Use Gradle's provided APIs instead of `project` or `System` • Modify artifacts through AndroidComponents API • Optimize project structure to reduce re-compilation scope and increase parallelism • Use Build Scan and Develocity Plugin

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About Me • Bunjiro Miyoshi (id: RyuNen344) • KMPΛֶΜͩΒͳ͔ͥGradleͷ஌͕ࣝ૿͑ͨ • Kodee͘Μݟ͔͚ͨΒͥͻ #KodeeEverywhere ͷϋογϡλάΛ͚ͭͯᄁ͖Λʂ

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Appendix

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Q. What’s next ? A. Lazy Con fi guration • Gradle 8.14.3 : Con fi gurations are initialized lazily • https://docs.gradle.org/8.14.3/ release- notes.html#con fi gurations-are- initialized-lazily • AGP 8.12.0 supports lazy con fi guration • https://issuetracker.google.com/ issues/416349489

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Q. What’s next ? A. Isolated Projects • https://docs.gradle.org/current/userguide/isolated_projects.html • Isolated Projects extends the con fi guration cache • the con fi guration model of Gradle projects are "isolated" from each other • Make con fi guration cache more immutable • Make con fi guration cache safely run in parallel

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Improvements of o ff i cial documents • JetBrains - Working with Gradle • https://www.jetbrains.com/guide/java/tutorials/working-with-gradle/ • Android Developers - Con fi gure your build • https://developer.android.com/studio/build • Android Developers - Write Gradle plugins • https://developer.android.com/build/extend-agp • Gradle - Improve the Performance of Gradle Builds • https://docs.gradle.org/current/userguide/performance.html • Gradle - Cookbook • https://cookbook.gradle.org/

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EOF