Add example of library usage in a Gradle build (#452)

Add a tested example to support the use case of a Gradle build. Related
to #404 aiming to prevent regressions around this use case.

Author: gabrielfeo

.gitignore

@@ -8,8 +8,7 @@ profile-out*
 
 build
 !.github/actions/build
-!*/src/**/build
-!*/*/src/**/build
+!**/src/**/build
 .ipynb_checkpoints
 
 .venv

README.md

@@ -10,6 +10,7 @@ A Kotlin library to access the [Develocity API][1], easy to use from:
 - [Jupyter notebooks with the Kotlin kernel][29]
 - [Kotlin scripts (`kts`)][27]
 - [Kotlin projects][28]
+- [Gradle tasks][36]
 
 ```kotlin
 val api = DevelocityApi.newInstance()
@@ -232,3 +233,4 @@ For general discussions or questions, feel free to reach out to maintainers on t
 [33]: https://github.com/gradle/develocity-api-samples
 [34]: https://github.com/gabrielfeo/develocity-api-kotlin/blob/main/build-logic/src/functionalTest/kotlin/com/gabrielfeo/task/PostProcessGeneratedApiTest.kt#L21
 [35]: https://community.gradle.org/#community-channels
+[36]: ./examples/example-gradle-task/

build-logic/src/main/kotlin/com/gabrielfeo/examples-test-suite.gradle.kts

@@ -24,7 +24,11 @@ kotlin {
 
 val examples = fileTree(rootDir) {
     include("examples/**")
-    exclude("**/build", "**/.*")
+    exclude {
+        it.isDirectory
+            && (it.name == "build" || it.name.startsWith("."))
+            && !it.path.endsWith("build-logic/src/main/kotlin/build")
+    }
 }
 
 tasks.named("processExamplesTestResources", ProcessResources::class) {

examples/example-gradle-task/README.md

@@ -0,0 +1,20 @@
+
+
+# Example usage in build logic
+
+This example shows how to create a reusable Gradle plugin that adds a `userBuildPerformanceMetrics` task to fetch and print build performance metrics for a specific user, using the Develocity API Kotlin client.
+
+## Core files
+
+- [`build-logic/src/main/kotlin/build/logic/PerformanceMetricsTask.kt`](./build-logic/src/main/kotlin/build/logic/PerformanceMetricsTask.kt): Implements a custom Gradle task that fetches and prints build performance metrics of a given user.
+- [`build-logic/src/main/kotlin/build/logic/DevelocityApiService.kt`](./build-logic/src/main/kotlin/build/logic/DevelocityApiService.kt): Defines a shared build service containing the Develocity API client, which could be used by multiple tasks while ensuring a singleton client per build.
+- [`build-logic/performance-metrics-plugin.gradle.kts`](./build-logic/performance-metrics-plugin.gradle.kts): A plugin which registers the task where it's applied.
+- [`build.gradle.kts`](./build.gradle.kts): Applies `performance-metrics-plugin`, making the task available for this build.
+
+## Usage
+
+Run:
+
+```sh
+./gradlew userBuildPerformanceMetrics [--user=foo] --period=[-1d|-7d|-14d|-30d|...]
+```

examples/example-gradle-task/build-logic/build.gradle.kts

@@ -0,0 +1,8 @@
+plugins {
+    `kotlin-dsl`
+}
+
+dependencies {
+    implementation("com.gabrielfeo:develocity-api-kotlin:2024.3.0")
+    implementation("org.apache.commons:commons-math3:3.6.1")
+}

examples/example-gradle-task/build-logic/settings.gradle.kts

@@ -0,0 +1,8 @@
+rootProject.name = "dak-example-gradle-task-build-logic"
+
+dependencyResolutionManagement {
+    repositories {
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}

examples/example-gradle-task/build-logic/src/main/kotlin/build/logic/DevelocityApiService.kt

@@ -0,0 +1,24 @@
+package build.logic
+
+import com.gabrielfeo.develocity.api.Config
+import com.gabrielfeo.develocity.api.DevelocityApi
+import org.gradle.api.services.BuildService
+import org.gradle.api.services.BuildServiceParameters
+import okhttp3.OkHttpClient
+
+abstract class DevelocityApiService
+    : DevelocityApi by DevelocityApi.newInstance(config()),
+      BuildService<BuildServiceParameters.None>,
+      AutoCloseable {
+
+    override fun close() {
+        shutdown()
+    }
+}
+
+private fun config() = Config(
+    // Necessary to accomodate Gradle's build service lifecycle because library
+    // uses a singleton OkHttpClient.Builder unless one is provided.
+    // See https://github.com/gabrielfeo/develocity-api-kotlin/issues/451
+    clientBuilder = OkHttpClient.Builder(),
+)

examples/example-gradle-task/build-logic/src/main/kotlin/build/logic/PerformanceMetricsTask.kt

@@ -0,0 +1,92 @@
+package build.logic
+
+import com.gabrielfeo.develocity.api.DevelocityApi
+import kotlinx.coroutines.runBlocking
+import com.gabrielfeo.develocity.api.model.BuildModelName
+import com.gabrielfeo.develocity.api.model.Build
+import com.gabrielfeo.develocity.api.model.GradleBuildCachePerformance
+import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics
+import org.gradle.api.DefaultTask
+import org.gradle.api.provider.Property
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.Optional
+import org.gradle.api.tasks.TaskAction
+import org.gradle.api.tasks.options.Option
+import org.gradle.api.services.ServiceReference
+import java.time.Duration
+
+
+abstract class PerformanceMetricsTask(
+
+) : DefaultTask() {
+
+    @get:Optional
+    @get:Input
+    @get:Option(
+        option = "user",
+        description = "The user to query builds for. Defaults to the current OS username."
+    )
+    abstract val user: Property<String>
+
+    @get:Optional
+    @get:Input
+    @get:Option(
+        option = "period",
+        description = "The period to query builds for (e.g. -14d, -30d, etc). Default: -14d."
+    )
+    abstract val period: Property<String>
+
+    @get:ServiceReference
+    abstract val api: Property<DevelocityApiService>
+
+    @TaskAction
+    fun run() {
+        val user = user.getOrElse(System.getProperty("user.name"))
+        val startTime = period.getOrElse("-14d")
+        val metrics = runBlocking {
+            getUserBuildsPerformanceMetrics(api.get(), user, startTime)
+        }
+        logger.quiet(metrics)
+    }
+
+    suspend fun getUserBuildsPerformanceMetrics(
+        api: DevelocityApi,
+        user: String,
+        startTime: String,
+    ): String {
+        val query = """user:"$user" buildStartTime>$startTime"""
+        val buildsPerformanceData = fetchBuildsPerformanceData(api, query)
+        val serializationFactors = buildsPerformanceData
+            .map { it.serializationFactor }
+            .let { DescriptiveStatistics(it.toDoubleArray()) }
+        val avoidanceSavings = buildsPerformanceData
+            .map { it.workUnitAvoidanceSavingsSummary.ratio }
+            .let { DescriptiveStatistics(it.toDoubleArray()) }
+        val heading = "Build performance overview for $user since $startTime (powered by Develocity®)"
+        return """
+            |
+            |${"\u001B[1;36m"}$heading${"\u001B[0m"}
+            |  ▶︎ Serialization factor: %.1fx
+            |      (Gradle's parallel execution)
+            |  ⏩︎ Avoidance savings: %.1f%% (mean) ~ %.1f%% (p95)
+            |      (Gradle and Develocity's mechanisms, incl. incremental build and remote cache)
+        """.trimMargin().format(
+            serializationFactors.mean,
+            avoidanceSavings.mean,
+            avoidanceSavings.getPercentile(95.0),
+        )
+    }
+
+    private suspend fun fetchBuildsPerformanceData(
+        api: DevelocityApi,
+        query: String,
+    ): List<GradleBuildCachePerformance> {
+        return api.buildsApi.getBuilds(
+            fromInstant = 0,
+            query = query,
+            models = listOf(BuildModelName.gradleBuildCachePerformance),
+        ).mapNotNull { build ->
+            build.models?.gradleBuildCachePerformance?.model
+        }
+    }
+}

examples/example-gradle-task/build-logic/src/main/kotlin/build/logic/performance-metrics-plugin.gradle.kts

@@ -0,0 +1,8 @@
+package build.logic
+
+gradle.sharedServices.registerIfAbsent("develocityApiService", DevelocityApiService::class)
+
+tasks.register<PerformanceMetricsTask>("userBuildPerformanceMetrics") {
+    group = "Develocity"
+    description = "Retrieves performance metrics for the user's builds from Develocity API."
+}

examples/example-gradle-task/build.gradle.kts

@@ -0,0 +1,3 @@
+plugins {
+    id("build.logic.performance-metrics-plugin")
+}