Make call to service loader in reactor integrations optimizable by R8

Fixes #1817

Author: qwwdfsad

reactive/kotlinx-coroutines-reactive/src/Await.kt

@@ -82,16 +82,6 @@ public suspend fun <T> Publisher<T>.awaitSingle(): T = awaitOne(Mode.SINGLE)
 
 // ------------------------ private ------------------------
 
-// ContextInjector service is implemented in `kotlinx-coroutines-reactor` module only.
-// If `kotlinx-coroutines-reactor` module is not included, the list is empty.
-private val contextInjectors: Array<ContextInjector> =
-    ServiceLoader.load(ContextInjector::class.java, ContextInjector::class.java.classLoader).iterator().asSequence().toList().toTypedArray() // R8 opto
-
-private fun <T> Publisher<T>.injectCoroutineContext(coroutineContext: CoroutineContext) =
-    contextInjectors.fold(this) { pub, contextInjector ->
-        contextInjector.injectCoroutineContext(pub, coroutineContext)
-    }
-
 private enum class Mode(val s: String) {
     FIRST("awaitFirst"),
     FIRST_OR_DEFAULT("awaitFirstOrDefault"),

reactive/kotlinx-coroutines-reactive/src/ReactiveFlow.kt

@@ -140,13 +140,14 @@ private class ReactiveSubscriber<T : Any>(
 
 // ContextInjector service is implemented in `kotlinx-coroutines-reactor` module only.
 // If `kotlinx-coroutines-reactor` module is not included, the list is empty.
-private val contextInjectors: List<ContextInjector> =
-    ServiceLoader.load(ContextInjector::class.java, ContextInjector::class.java.classLoader).toList()
+private val contextInjectors: Array<ContextInjector> =
+    ServiceLoader.load(ContextInjector::class.java, ContextInjector::class.java.classLoader)
+        .iterator().asSequence()
+        .toList().toTypedArray() // R8 opto
 
-private fun <T> Publisher<T>.injectCoroutineContext(coroutineContext: CoroutineContext) =
+internal fun <T> Publisher<T>.injectCoroutineContext(coroutineContext: CoroutineContext) =
     contextInjectors.fold(this) { pub, contextInjector -> contextInjector.injectCoroutineContext(pub, coroutineContext) }
 
-
 /**
  * Adapter that transforms [Flow] into TCK-complaint [Publisher].
  * [cancel] invocation cancels the original flow.

ui/kotlinx-coroutines-android/build.gradle

@@ -77,7 +77,7 @@ task runR8(type: RunR8Task, dependsOn: 'jar'){
     inputConfig = file('testdata/r8-test-rules.pro')
 }
 
-task runR8NoOptim(type: RunR8Task, dependsOn: 'jar'){
+task runR8NoOptim(type: RunR8Task, dependsOn: 'jar') {
     outputDex = unOptimizedDexDir
     inputConfig = file('testdata/r8-test-rules-no-optim.pro')
 }
@@ -103,4 +103,4 @@ tasks.withType(dokka.getClass()) {
         url = new URL("https://developer.android.com/reference/")
         packageListUrl = projectDir.toPath().resolve("package.list").toUri().toURL()
     }
-}
+}

ui/kotlinx-coroutines-android/test/R8ServiceLoaderOptimizationTest.kt

@@ -16,7 +16,7 @@ class R8ServiceLoaderOptimizationTest : TestBase() {
     private val r8DexNoOptim = File(System.getProperty("noOptimDexPath")!!).asDexFile()
 
     @Test
-    fun noServiceLoaderCalls() {
+    fun testNoServiceLoaderCalls() {
         val serviceLoaderInvocations = r8Dex.types.any {
             it.type == "Ljava/util/ServiceLoader;"
         }
@@ -28,7 +28,7 @@ class R8ServiceLoaderOptimizationTest : TestBase() {
     }
 
     @Test
-    fun androidDispatcherIsKept() {
+    fun testAndroidDispatcherIsKept() {
         val hasAndroidDispatcher = r8DexNoOptim.classes.any {
             it.type == "Lkotlinx/coroutines/android/AndroidDispatcherFactory;"
         }
@@ -38,7 +38,7 @@ class R8ServiceLoaderOptimizationTest : TestBase() {
 
     @Test
     @Ignore
-    fun noOptimRulesMatch() {
+    fun testNoOptimRulesMatch() {
         val paths = listOf(
                 "META-INF/com.android.tools/proguard/coroutines.pro",
                 "META-INF/proguard/coroutines.pro",