Add DSL helpers to enable metrics and reports

redwood-gradle-plugin/src/main/kotlin/app/cash/redwood/gradle/RedwoodComposeExtension.kt

@@ -15,12 +15,10 @@
  */
 package app.cash.redwood.gradle
 
-import javax.inject.Inject
-import org.gradle.api.model.ObjectFactory
+import org.gradle.api.Action
 import org.gradle.api.provider.Property
 
-public abstract class RedwoodComposeExtension
-@Inject constructor(objectFactory: ObjectFactory) {
+public interface RedwoodComposeExtension {
   /**
    * The version of the JetBrains Compose compiler to use, or a Maven coordinate triple of
    * the custom Compose compiler to use.
@@ -39,7 +37,48 @@ public abstract class RedwoodComposeExtension
    * }
    * ```
    */
-  public val kotlinCompilerPlugin: Property<String> =
-    objectFactory.property(String::class.java)
-      .convention(composeCompilerVersion)
+  public val kotlinCompilerPlugin: Property<String>
+
+  /**
+   * Configuration options that require extra care when used.
+   *
+   * @see DangerZone
+   */
+  public fun dangerZone(body: Action<DangerZone>)
+
+  /**
+   * Configuration options that require extra care when used. Please read the documentation of
+   * each member carefully to understand how it affects your build.
+   */
+  public interface DangerZone {
+    /**
+     * Enable the output of metrics from the Compose compiler.
+     *
+     * Text files will be written to `generated/redwood/compose-metrics/` in the project's build
+     * directory. See
+     * [the compiler documentation](https://github.com/androidx/androidx/blob/androidx-main/compose/compiler/design/compiler-metrics.md#reports-breakdown)
+     * for more information about the contents.
+     *
+     * **NOTE:** This should only be enabled during investigation as it breaks the use of
+     * Gradle's build cache for this project's Kotlin compilation tasks.
+     *
+     * @see enableReports
+     */
+    public fun enableMetrics()
+
+    /**
+     * Enable the output of reports from the Compose compiler.
+     *
+     * Text files will be written to `generated/redwood/compose-reports/` in the project's build
+     * directory. See
+     * [the compiler documentation](https://github.com/androidx/androidx/blob/androidx-main/compose/compiler/design/compiler-metrics.md#reports-breakdown)
+     * for more information about the contents.
+     *
+     * **NOTE:** This should only be enabled during investigation as it breaks the use of
+     * Gradle's build cache for this project's Kotlin compilation tasks.
+     *
+     * @see enableMetrics
+     */
+    public fun enableReports()
+  }
 }

redwood-gradle-plugin/src/main/kotlin/app/cash/redwood/gradle/RedwoodComposeExtensionImpl.kt

@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2023 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package app.cash.redwood.gradle
+
+import app.cash.redwood.gradle.RedwoodComposeExtension.DangerZone
+import org.gradle.api.Action
+import org.gradle.api.Project
+import org.gradle.api.provider.Property
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+internal class RedwoodComposeExtensionImpl(
+  private val project: Project,
+) : RedwoodComposeExtension, DangerZone {
+  private var metricsEnabled = false
+  private var reportsEnabled = false
+
+  // Explicit backing property avoids Gradle attempting to reflect on an implicit backing field.
+  override val kotlinCompilerPlugin: Property<String> get() = _kotlinCompilerPlugin
+
+  private val _kotlinCompilerPlugin = project.objects.property(String::class.java)
+    .convention(composeCompilerVersion)
+
+  override fun dangerZone(body: Action<DangerZone>) {
+    body.execute(this)
+  }
+
+  override fun enableMetrics() {
+    if (metricsEnabled) return
+    metricsEnabled = true
+
+    project.tasks.withType(KotlinCompile::class.java).configureEach {
+      val dir = project.redwoodReportDir("compose-metrics/${it.name}").get().asFile.absolutePath
+      it.compilerOptions.freeCompilerArgs.addAll(
+        "-P",
+        "plugin:androidx.compose.compiler.plugins.kotlin:metricsDestination=$dir",
+      )
+    }
+  }
+
+  override fun enableReports() {
+    if (reportsEnabled) return
+    reportsEnabled = true
+
+    project.tasks.withType(KotlinCompile::class.java).configureEach {
+      val dir = project.redwoodReportDir("compose-reports/${it.name}").get().asFile.absolutePath
+      it.compilerOptions.freeCompilerArgs.addAll(
+        "-P",
+        "plugin:androidx.compose.compiler.plugins.kotlin:reportsDestination=$dir",
+      )
+    }
+  }
+}

redwood-gradle-plugin/src/main/kotlin/app/cash/redwood/gradle/RedwoodComposePlugin.kt

@@ -38,7 +38,12 @@ public class RedwoodComposePlugin : KotlinCompilerPluginSupportPlugin {
   override fun apply(target: Project) {
     super.apply(target)
 
-    extension = target.extensions.create(EXTENSION_NAME, RedwoodComposeExtension::class.java)
+    extension = RedwoodComposeExtensionImpl(target)
+    target.extensions.add(
+      RedwoodComposeExtension::class.java,
+      EXTENSION_NAME,
+      extension,
+    )
 
     target.plugins.withId("org.jetbrains.compose") {
       throw IllegalStateException(

redwood-gradle-plugin/src/main/kotlin/app/cash/redwood/gradle/RedwoodGeneratorPlugin.kt

@@ -88,7 +88,7 @@ public abstract class RedwoodGeneratorPlugin(
       it.description = "Generate Redwood Kotlin sources"
 
       it.toolClasspath.from(toolingConfiguration)
-      it.outputDir.set(project.layout.buildDirectory.dir("generated/redwood"))
+      it.outputDir.set(project.redwoodGeneratedDir("sources"))
       it.generatorFlag.set(strategy.generatorFlag)
       it.schemaType.set(extension.type)
       it.classpath.from(schemaConfiguration)

redwood-gradle-plugin/src/main/kotlin/app/cash/redwood/gradle/RedwoodSchemaPlugin.kt

@@ -62,7 +62,7 @@ public class RedwoodSchemaPlugin : Plugin<Project> {
       it.description = "Generate parsed schema JSON"
 
       it.toolClasspath.from(toolingConfiguration)
-      it.outputDir.set(project.layout.buildDirectory.dir("generated/redwood"))
+      it.outputDir.set(project.redwoodGeneratedDir("schema-json"))
       it.schemaType.set(extension.type)
       it.classpath.from(classpath, compilation.output.classesDirs)
     }

redwood-gradle-plugin/src/main/kotlin/app/cash/redwood/gradle/util.kt

@@ -16,6 +16,9 @@
 package app.cash.redwood.gradle
 
 import org.gradle.api.Project
+import org.gradle.api.file.Directory
+import org.gradle.api.provider.Provider
+import org.gradle.api.reporting.ReportingExtension
 
 internal fun Project.redwoodDependency(artifactId: String): Any {
   // Indicates when the plugin is applied inside the Redwood repo to Redwood's own modules. This
@@ -28,3 +31,11 @@ internal fun Project.redwoodDependency(artifactId: String): Any {
     "app.cash.redwood:$artifactId:$redwoodVersion"
   }
 }
+
+internal fun Project.redwoodGeneratedDir(name: String): Provider<Directory> {
+  return layout.buildDirectory.dir("generated/redwood/$name")
+}
+
+internal fun Project.redwoodReportDir(name: String): Provider<Directory> {
+  return extensions.getByType(ReportingExtension::class.java).baseDirectory.dir("redwood/$name")
+}

redwood-gradle-plugin/src/test/fixture/compose-compiler-metrics/build.gradle

@@ -0,0 +1,31 @@
+buildscript {
+  dependencies {
+    classpath "app.cash.redwood:redwood-gradle-plugin:$redwoodVersion"
+    classpath libs.kotlin.gradlePlugin
+  }
+
+  repositories {
+    maven {
+      url "file://${rootDir.absolutePath}/../../../../../build/localMaven"
+    }
+    mavenCentral()
+    google()
+  }
+}
+
+apply plugin: 'org.jetbrains.kotlin.jvm'
+apply plugin: 'app.cash.redwood'
+
+redwood {
+  dangerZone {
+    enableMetrics()
+  }
+}
+
+repositories {
+  maven {
+    url "file://${rootDir.absolutePath}/../../../../../build/localMaven"
+  }
+  mavenCentral()
+  google()
+}

redwood-gradle-plugin/src/test/fixture/compose-compiler-metrics/settings.gradle

@@ -0,0 +1,7 @@
+dependencyResolutionManagement {
+  versionCatalogs {
+    libs {
+      from(files('../../../../../gradle/libs.versions.toml'))
+    }
+  }
+}

redwood-gradle-plugin/src/test/fixture/compose-compiler-metrics/src/main/kotlin/com/example/double.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2023 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example
+
+import androidx.compose.runtime.Composable
+
+@Composable
+fun double(value: Int): Int {
+  return value * 2
+}

redwood-gradle-plugin/src/test/fixture/compose-compiler-reports/build.gradle

@@ -0,0 +1,31 @@
+buildscript {
+  dependencies {
+    classpath "app.cash.redwood:redwood-gradle-plugin:$redwoodVersion"
+    classpath libs.kotlin.gradlePlugin
+  }
+
+  repositories {
+    maven {
+      url "file://${rootDir.absolutePath}/../../../../../build/localMaven"
+    }
+    mavenCentral()
+    google()
+  }
+}
+
+apply plugin: 'org.jetbrains.kotlin.jvm'
+apply plugin: 'app.cash.redwood'
+
+redwood {
+  dangerZone {
+    enableReports()
+  }
+}
+
+repositories {
+  maven {
+    url "file://${rootDir.absolutePath}/../../../../../build/localMaven"
+  }
+  mavenCentral()
+  google()
+}

redwood-gradle-plugin/src/test/fixture/compose-compiler-reports/settings.gradle

@@ -0,0 +1,7 @@
+dependencyResolutionManagement {
+  versionCatalogs {
+    libs {
+      from(files('../../../../../gradle/libs.versions.toml'))
+    }
+  }
+}

redwood-gradle-plugin/src/test/fixture/compose-compiler-reports/src/main/kotlin/com/example/double.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2023 Square, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example
+
+import androidx.compose.runtime.Composable
+
+@Composable
+fun double(value: Int): Int {
+  return value * 2
+}

redwood-gradle-plugin/src/test/kotlin/app/cash/redwood/gradle/FixtureTest.kt

@@ -15,11 +15,15 @@
  */
 package app.cash.redwood.gradle
 
+import assertk.all
 import assertk.assertThat
 import assertk.assertions.contains
 import assertk.assertions.containsExactly
+import assertk.assertions.containsOnly
+import assertk.assertions.exists
 import assertk.assertions.isEqualTo
 import assertk.assertions.isNotEmpty
+import assertk.assertions.isNotNull
 import assertk.assertions.prop
 import java.io.File
 import org.gradle.testkit.runner.BuildTask
@@ -208,6 +212,34 @@ class FixtureTest {
     )
   }
 
+  @Test fun composeCompilerMetrics() {
+    val fixtureDir = File("src/test/fixture/compose-compiler-metrics")
+    fixtureGradleRunner(fixtureDir).build()
+    assertThat(fixtureDir.resolve("build/reports/redwood/compose-metrics/compileKotlin")).all {
+      exists()
+      prop("children", File::list)
+        .isNotNull()
+        .containsOnly(
+          "compose-compiler-metrics-module.json",
+        )
+    }
+  }
+
+  @Test fun composeCompilerReports() {
+    val fixtureDir = File("src/test/fixture/compose-compiler-reports")
+    fixtureGradleRunner(fixtureDir).build()
+    assertThat(fixtureDir.resolve("build/reports/redwood/compose-reports/compileKotlin")).all {
+      exists()
+      prop("children", File::list)
+        .isNotNull()
+        .containsOnly(
+          "compose-compiler-reports-classes.txt",
+          "compose-compiler-reports-composables.csv",
+          "compose-compiler-reports-composables.txt",
+        )
+    }
+  }
+
   private fun fixtureGradleRunner(
     fixtureDir: File,
     vararg tasks: String = arrayOf("clean", "build"),