SchedulerTask is now an abstract class with optimizations for jvm

* It removes the need for a separate SchedulerTaskBase
* submissionTime and taskContext are marked as @JvmField
* DispatchedTask is also an abstract class
* resumeMode is marked as @JvmField

Author: elizarov

common/kotlinx-coroutines-core-common/src/AbstractContinuation.kt

@@ -18,8 +18,8 @@ private const val RESUMED = 2
  */
 internal abstract class AbstractContinuation<in T>(
     public final override val delegate: Continuation<T>,
-    public final override val resumeMode: Int
-) : SchedulerTaskBase(), Continuation<T>, DispatchedTask<T> {
+    resumeMode: Int
+) : DispatchedTask<T>(resumeMode), Continuation<T> {
 
     /*
      * Implementation notes

common/kotlinx-coroutines-core-common/src/Dispatched.kt

@@ -81,11 +81,10 @@ internal object UndispatchedEventLoop {
 internal class DispatchedContinuation<in T>(
     @JvmField val dispatcher: CoroutineDispatcher,
     @JvmField val continuation: Continuation<T>
-) : SchedulerTaskBase(), Continuation<T> by continuation, DispatchedTask<T> {
+) : DispatchedTask<T>(MODE_ATOMIC_DEFAULT), Continuation<T> by continuation {
     @JvmField
     @Suppress("PropertyName")
     internal var _state: Any? = UNDEFINED
-    public override var resumeMode: Int = 0
     @JvmField // pre-cached value to avoid ctx.fold on every resumption
     internal val countOrElement = threadContextElements(context)
 
@@ -204,20 +203,21 @@ internal fun <T> Continuation<T>.resumeDirectWithException(exception: Throwable)
     else -> resumeWithException(exception)
 }
 
-internal interface DispatchedTask<in T> : SchedulerTask {
-    public val delegate: Continuation<T>
-    public val resumeMode: Int get() = MODE_CANCELLABLE
+internal abstract class DispatchedTask<in T>(
+    @JvmField var resumeMode: Int
+) : SchedulerTask() {
+    public abstract val delegate: Continuation<T>
 
-    public fun takeState(): Any?
+    public abstract fun takeState(): Any?
 
     @Suppress("UNCHECKED_CAST")
-    public fun <T> getSuccessfulResult(state: Any?): T =
+    public open fun <T> getSuccessfulResult(state: Any?): T =
         state as T
 
     public fun getExceptionalResult(state: Any?): Throwable? =
         (state as? CompletedExceptionally)?.cause
 
-    public override fun run() {
+    public final override fun run() {
         val taskContext = this.taskContext
         try {
             val delegate = delegate as DispatchedContinuation<T>

common/kotlinx-coroutines-core-common/src/SchedulerTask.common.kt

@@ -4,9 +4,7 @@
 
 package kotlinx.coroutines
 
-internal expect interface SchedulerTask : Runnable 
-
-internal expect abstract class SchedulerTaskBase() : SchedulerTask
+internal expect abstract class SchedulerTask() : Runnable
 
 internal expect interface SchedulerTaskContext
 

core/kotlinx-coroutines-core/src/SchedulerTask.kt

@@ -8,11 +8,6 @@ import kotlinx.coroutines.scheduling.*
 
 internal actual typealias SchedulerTask = Task
 
-internal actual abstract class SchedulerTaskBase actual constructor() : SchedulerTask {
-    override var submissionTime: Long = 0
-    override var taskContext: TaskContext = NonBlockingContext
-}
-
 internal actual typealias SchedulerTaskContext = TaskContext
 
 @Suppress("EXTENSION_SHADOWED_BY_MEMBER")

core/kotlinx-coroutines-core/src/scheduling/Tasks.kt

@@ -82,18 +82,20 @@ internal object NonBlockingContext : TaskContext {
     }
 }
 
-internal interface Task : Runnable {
-    var submissionTime: Long
-    var taskContext: TaskContext
+internal abstract class Task(
+    @JvmField var submissionTime: Long,
+    @JvmField var taskContext: TaskContext
+) : Runnable {
+    constructor() : this(0, NonBlockingContext)
     val mode: TaskMode get() = taskContext.taskMode
 }
 
 // Non-reusable Task implementation to wrap Runnable instances that do not otherwise implement task
 internal class TaskImpl(
     @JvmField val block: Runnable,
-    override var submissionTime: Long,
-    override var taskContext: TaskContext
-) : SchedulerTaskBase() {
+    submissionTime: Long,
+    taskContext: TaskContext
+) : Task(submissionTime, taskContext) {
     override fun run() {
         try {
             block.run()

js/kotlinx-coroutines-core-js/src/SchedulerTask.kt

@@ -4,10 +4,7 @@
 
 package kotlinx.coroutines
 
-@Suppress("ACTUAL_WITHOUT_EXPECT")
-internal actual typealias SchedulerTask = Runnable
-
-internal actual abstract class SchedulerTaskBase actual constructor() : SchedulerTask
+internal actual abstract class SchedulerTask : Runnable
 
 @Suppress("ACTUAL_WITHOUT_EXPECT")
 internal actual typealias SchedulerTaskContext = Unit

native/kotlinx-coroutines-core-native/src/SchedulerTask.kt

@@ -4,10 +4,7 @@
 
 package kotlinx.coroutines
 
-@Suppress("ACTUAL_WITHOUT_EXPECT")
-internal actual typealias SchedulerTask = Runnable
-
-internal actual abstract class SchedulerTaskBase actual constructor() : SchedulerTask
+internal actual abstract class SchedulerTask : Runnable
 
 @Suppress("ACTUAL_WITHOUT_EXPECT")
 internal actual typealias SchedulerTaskContext = Unit