Issue #309: Consume Fenix megazord; enable Rust logging

app/build.gradle

@@ -8,6 +8,17 @@ apply plugin: 'kotlin-android-extensions'
 apply from: "$project.rootDir/automation/gradle/versionCode.gradle"
 apply plugin: 'androidx.navigation.safeargs'
 
+apply plugin: 'org.mozilla.appservices'
+
+appservices {
+    defaultConfig {
+        megazord = 'fenix'
+        // Necessary to allow for local dependency substitutions.
+        // See https://github.com/mozilla-mobile/reference-browser/pull/356#issuecomment-449190236
+        unitTestingEnabled = false
+    }
+}
+
 android {
     compileSdkVersion 28
     defaultConfig {
@@ -183,6 +194,7 @@ dependencies {
     implementation Deps.mozilla_service_glean
 
     implementation Deps.mozilla_support_ktx
+    implementation Deps.mozilla_support_rustlog
 
     implementation Deps.mozilla_ui_colors
     implementation Deps.mozilla_ui_icons

app/src/main/java/org/mozilla/fenix/FenixApplication.kt

@@ -19,6 +19,7 @@ import mozilla.components.service.glean.Glean
 import mozilla.components.support.base.log.Log
 import mozilla.components.support.base.log.logger.Logger
 import mozilla.components.support.base.log.sink.AndroidLogSink
+import mozilla.components.support.rustlog.RustLog
 import org.mozilla.fenix.components.Components
 import java.io.File
 
@@ -31,7 +32,8 @@ open class FenixApplication : Application() {
     override fun onCreate() {
         super.onCreate()
 
-        Log.addSink(AndroidLogSink())
+        val megazordEnabled = setupMegazord()
+        setupLogging(megazordEnabled)
         setupCrashReporting()
 
         if (!isMainProcess(this)) {
@@ -55,6 +57,18 @@ open class FenixApplication : Application() {
         // no-op, LeakCanary is disabled by default
     }
 
+    private fun setupLogging(megazordEnabled: Boolean) {
+        // We want the log messages of all builds to go to Android logcat
+        Log.addSink(AndroidLogSink())
+
+        if (megazordEnabled) {
+            // We want rust logging to go through the log sinks.
+            // This has to happen after initializing the megazord, and
+            // it's only worth doing in the case that we are a megazord.
+            RustLog.enable()
+        }
+    }
+
     private fun setupGlean(context: Context) {
         Glean.initialize(context)
         Glean.setUploadEnabled(BuildConfig.TELEMETRY)
@@ -91,6 +105,38 @@ open class FenixApplication : Application() {
             .crashReporter
             .install(this)
     }
+
+    /**
+     * Initiate Megazord sequence! Megazord Battle Mode!
+     *
+     * Mozilla Application Services publishes many native (Rust) code libraries that stand alone: each published Android
+     * ARchive (AAR) contains managed code (classes.jar) and multiple .so library files (one for each supported
+     * architecture). That means consuming multiple such libraries entails at least two .so libraries, and each of those
+     * libraries includes the entire Rust standard library as well as (potentially many) duplicated dependencies. To
+     * save space and allow cross-component native-code Link Time Optimization (LTO, i.e., inlining, dead code
+     * elimination, etc).
+     * Application Services also publishes composite libraries -- so called megazord libraries or just megazords -- that
+     * compose multiple Rust components into a single optimized .so library file.
+     *
+     * @return Boolean indicating if we're in a megazord.
+     */
+    private fun setupMegazord(): Boolean {
+        // mozilla.appservices.FenixMegazord will be missing if we're doing an application-services
+        // dependency substitution locally. That class is supplied dynamically by the org.mozilla.appservices
+        // gradle plugin, and that won't happen if we're not megazording. We won't megazord if we're
+        // locally substituting every module that's part of the megazord's definition, which is what
+        // happens during a local substitution of application-services.
+        // As a workaround, use reflections to conditionally initialize the megazord in case it's present.
+        return try {
+            val megazordClass = Class.forName("mozilla.appservices.FenixMegazord")
+            val megazordInitMethod = megazordClass.getDeclaredMethod("init")
+            megazordInitMethod.invoke(megazordClass)
+            true
+        } catch (e: ClassNotFoundException) {
+            Logger.info("mozilla.appservices.FenixMegazord not found; skipping megazord init.")
+            false
+        }
+    }
 }
 
 /**

build.gradle

@@ -8,6 +8,7 @@ buildscript {
     dependencies {
         classpath Deps.tools_androidgradle
         classpath Deps.tools_kotlingradle
+        classpath Deps.tools_appservicesgradle
         classpath Deps.androidx_safeargs
         classpath Deps.allopen
 

buildSrc/src/main/java/Dependencies.kt

@@ -21,6 +21,7 @@ private object Versions {
     const val androidx_fragment = "1.1.0-alpha04"
     const val androidx_safeargs = "1.0.0-beta01"
 
+    const val appservices_gradle_plugin = "0.3.1"
     const val mozilla_android_components = "0.45.0-SNAPSHOT"
 
     const val test_tools = "1.0.2"
@@ -40,6 +41,7 @@ private object Versions {
 object Deps {
     const val tools_androidgradle = "com.android.tools.build:gradle:${Versions.android_gradle_plugin}"
     const val tools_kotlingradle = "org.jetbrains.kotlin:kotlin-gradle-plugin:${Versions.kotlin}"
+    const val tools_appservicesgradle = "org.mozilla.appservices:gradle-plugin:${Versions.appservices_gradle_plugin}"
     const val kotlin_stdlib = "org.jetbrains.kotlin:kotlin-stdlib-jdk7:${Versions.kotlin}"
 
     const val allopen =  "org.jetbrains.kotlin:kotlin-allopen:${Versions.kotlin}"
@@ -97,6 +99,7 @@ object Deps {
 
     const val mozilla_support_base = "org.mozilla.components:support-base:${Versions.mozilla_android_components}"
     const val mozilla_support_ktx = "org.mozilla.components:support-ktx:${Versions.mozilla_android_components}"
+    const val mozilla_support_rustlog = "org.mozilla.components:support-rustlog:${Versions.mozilla_android_components}"
 
     const val sentry = "io.sentry:sentry-android:${Versions.sentry}"
     const val leakcanary = "com.squareup.leakcanary:leakcanary-android:${Versions.leakcanary}"