Gradle.{org,com}

Gradle.org

Gradle Inc.

What is a modern build?

Build engineering

Gradle in a nutshell

Core Engine

Core Engine

├── [ 962]  build.gradle
├── [  96]  gradle
│       ├── [ 54K]  gradle-wrapper.jar
│       └── [ 202]  gradle-wrapper.properties
├── [5.8K]  gradlew
├── [2.9K]  gradlew.bat
├── [ 359]  settings.gradle

Plugins

A Java library (Groovy DSL)

plugins {
   id "java-library"
}

dependencies {
   api "com.acme:foo:1.0"
   implementation "com.zoo:monkey:1.1"
}

tasks.withType(JavaCompile) {
    // ...
}

A native app (Kotlin DSL)

plugins {
    `cpp-application`
}

application {
    baseName = "my-app"
}

toolChains {
    // ...
}

An Android App

apply plugin: 'com.android.application'

dependencies {
    implementation "androidx.appcompat:appcompat:1.0.2"
    // ...
}

android {
    compileSdkVersion 28
    buildToolsVersion "28.0.3"
    // ...
    defaultConfig {
        minSdkVersion 19
        targetSdkVersion 28
    }
    // ...
}

DEMO

Perf matters

What is slow?

Toolbelt

Build Scans

Gradle Profiler

check-no-tests {
    tasks = ["check"]
    gradle-args = ["-x", "test"]
    cleanup-tasks = ["clean"]
    run-using = tooling-api // value can also be "cli" or "no-daemon"
    warm-ups = 2
}

General Advice

Stay up-to-date

classpath 'com.android.tools.build:gradle:3.3.2'

JVM Tuning

Daemon

Parallelism

Build Cache

// root build.gradle
// only for kotlin < 1.3.30
subprojects {
	pluginManager.withPlugin("kotlin-kapt") {
		kapt.useBuildCache = true
	}
}

Where is the problem?

Build Lifecycle

Red flags

// settings.gradle
// do not do this
new File('.').eachFile(FileType.DIRECTORIES) { dir ->
    include dir.name
}

Startup / Settings / BuildSrc

Configuration

Configuration time

Execution

Incremental Builds

Faster Compilation

Resources

Configuration

What

When

Resolution at configuration time

Eager Resolution

task fatJar(type: Jar) {
    from configurations.compile.collect {
	it.isDirectory() ? it : zipTree(it)
    }
    with jar
    classifier = 'uber-jar'
}

Lazy Resolution

task fatJar(type: Jar) {
    from {
	configurations.compile.collect {
	    it.isDirectory() ? it : zipTree(it)
	}
    }
    with jar
    classifier = 'uber-jar'
}

Configuration Avoidance

tasks.register("fatJar", Jar) {
    from configurations.compile.collect {
        it.isDirectory() ? it : zipTree(it)
    }
    with jar
    classifier = 'uber-jar'
}

I/O at configuration time

I/O at configuration time

task projectStats {
    def statsFile = new File(buildDir, 'stats.txt')
    statsFile.parentFile.mkdirs()
    def javaFiles = sourceSets.main.java.size()
    def javaSize = sourceSets.main.java
	.collect{it.text.bytes}
	.flatten()
	.sum()
    statsFile.text = """
    |SourceFiles:  ${javaFiles}
    |Source size:  ${javaSize} bytes
    """.stripMargin()
}

I/O at configuration time

task projectStats {
    def statsFile = new File(buildDir, 'stats.txt')
    input.files sourceSet.main.java
    outputs.file statsFile
    doLast {
        statsFile.parentFile.mkdirs()
        def javaFiles = sourceSets.main.java.size()
        def javaSize = sourceSets.main.java
        	.collect{it.text.bytes}
        	.flatten()
        	.sum()
        statsFile.text = """
        |SourceFiles:  ${javaFiles}
        |Source size:  ${javaSize} bytes
        """.stripMargin()
    }
}

I/O at configuration time

task projectStats(type: ProjectStats) {
    statsFile = new File(buildDir, 'stats.txt')
    sources = sourceSet.main.java
}

class ProjectStats extends DefaultTask {
    @InputFiles FileCollection sources
    @OutputFile File statsFile

    @TaskAction def stats() {
      statsFile.text = """
      |Files: ${sources.size()}
      |Total: ${sources.collect{it.text.bytes}.flatten().sum()} bytes
      """.stripMargin()
    }
}

Inefficient Plugins

// version.gradle
def out = new ByteArrayOutputStream()
exec {
    commandLine 'git','rev-parse','HEAD'
    standardOutput = out
    workingDir = rootDir
}
version = new String(out.toByteArray())

// root 'build.gradle'
allprojects {
    apply from:'$rootDir/version.gradle'
}

Re-use expensive logic

// root 'build.gradle'
apply from:"$rootDir/version.gradle"

subprojects {
    version = rootProject.version
}

Variant explosion

variantFilter { variant ->
    def flavorName = variant.flavors[0].name
    def freeFlavor = flavorName == 'free'
    if(!freeFlavor && variant.buildType.name == 'release') {
        variant.ignore = true
    }
}

Configuration Time

Gradle build cache

Task caching

Usage scenarios

Mechanics

Enable caching

// only for kotlin < 1.3.30
subprojects {
    pluginManager.withPlugin("kotlin-kapt") {
        kapt.useBuildCache = true
    }
}

Cached unit tests

Android best practices

Remote cache

def runsOnCI = System.getEnv("CI") != null

buildCache {
    local {
        enabled = !runsOnCI
    }
    remote(HttpBuildCache) {
        push = runsOnCI
        url = 'https://my.server.com:8080/cache/'
	// if cache access is secured
	credentials {
	    username = 'cache-user'
	    password = 'super-secret-pw'
        }
    }
}

Gradle Remote Cache Backend

docker run -d \
	   -v /opt/build-cache-node:/data \
           -p 80:5071 \
	   gradle/build-cache-node:latest

Gradle Enterprise cache $$$

Improvements in AGP?

Improving Build Speed

Configuration Avoidance

Cacheability

Lint

Cacheability

Annotation Processing Improvements

Memory Leak Fixes

Databinding

Conclusion

Takeaways

Resources