Add name parameter to Handler.asCoroutineDispatcher

Fixes #580

Author: qwwdfsad

binary-compatibility-validator/reference-public-api/kotlinx-coroutines-android.txt

@@ -30,6 +30,8 @@ public abstract class kotlinx/coroutines/experimental/android/HandlerDispatcher
 public final class kotlinx/coroutines/experimental/android/HandlerDispatcherKt {
 	public static final fun awaitFrame (Lkotlin/coroutines/experimental/Continuation;)Ljava/lang/Object;
 	public static final fun from (Landroid/os/Handler;)Lkotlinx/coroutines/experimental/android/HandlerDispatcher;
+	public static final fun from (Landroid/os/Handler;Ljava/lang/String;)Lkotlinx/coroutines/experimental/android/HandlerDispatcher;
+	public static synthetic fun from$default (Landroid/os/Handler;Ljava/lang/String;ILjava/lang/Object;)Lkotlinx/coroutines/experimental/android/HandlerDispatcher;
 	public static final fun getMain (Lkotlinx/coroutines/experimental/Dispatchers;)Lkotlinx/coroutines/experimental/android/HandlerDispatcher;
 }
 

ui/kotlinx-coroutines-android/src/HandlerDispatcher.kt

@@ -37,11 +37,13 @@ public sealed class HandlerDispatcher : CoroutineDispatcher(), Delay {
 }
 
 /**
- * Represents an arbitrary [Handler] as a implementation of [CoroutineDispatcher].
+ * Represents an arbitrary [Handler] as a implementation of [CoroutineDispatcher]
+ * with an optional [name] for nicer debugging
  */
 @JvmName("from") // this is for a nice Java API, see issue #255
-public fun Handler.asCoroutineDispatcher(): HandlerDispatcher =
-    HandlerContext(this)
+@JvmOverloads
+public fun Handler.asCoroutineDispatcher(name: String? = null): HandlerDispatcher =
+    HandlerContext(this, name)
 
 private const val MAX_DELAY = Long.MAX_VALUE / 2 // cannot delay for too long on Android
 
@@ -139,7 +141,12 @@ public class HandlerContext private constructor(
     public suspend fun awaitFrame(): Long =
         kotlinx.coroutines.experimental.android.awaitFrame()
 
-    override fun toString() = name ?: handler.toString()
+    override fun toString(): String =
+        if (name != null) {
+            if (invokeImmediately) "$name [immediate]" else name
+        } else {
+            handler.toString()
+        }
 
     override fun equals(other: Any?): Boolean = other is HandlerContext && other.handler === handler
     override fun hashCode(): Int = System.identityHashCode(handler)

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

@@ -118,6 +118,15 @@ class HandlerDispatcherTest : TestBase() {
         job.join(mainLooper)
     }
 
+    @Test
+    fun testToString() {
+        ReflectionHelpers.setStaticField(Build.VERSION::class.java, "SDK_INT", 28)
+        val main = Looper.getMainLooper().asHandler(async = true).asCoroutineDispatcher("testName")
+        assertEquals("testName", main.toString())
+        assertEquals("testName [immediate]", main.immediate.toString())
+        assertEquals("testName [immediate]", main.immediate.immediate.toString())
+    }
+
     private suspend fun Job.join(mainLooper: ShadowLooper) {
         expect(1)
         mainLooper.unPause()