From ec89945d499e6aa1e686f2d6b6a9e13a67e02bb0 Mon Sep 17 00:00:00 2001
From: Fabian Mastenbroek <mail.fabianm@gmail.com>
Date: Sun, 3 Mar 2019 21:52:23 +0100
Subject: feat: Expose actor context in coroutine

This change makes a `SuspendingBehavior` instance expose its
`SuspendingActorContext` in the coroutine context, so suspending methods
inside the coroutine can access the actor context.
---
 .../com/atlarge/odcsim/coroutines/Behavior.kt      | 13 +++++++++---
 .../com/atlarge/odcsim/internal/Coroutines.kt      | 23 +++++-----------------
 2 files changed, 15 insertions(+), 21 deletions(-)

(limited to 'odcsim-core/src/main')

diff --git a/odcsim-core/src/main/kotlin/com/atlarge/odcsim/coroutines/Behavior.kt b/odcsim-core/src/main/kotlin/com/atlarge/odcsim/coroutines/Behavior.kt
index 4951d619..20aab232 100644
--- a/odcsim-core/src/main/kotlin/com/atlarge/odcsim/coroutines/Behavior.kt
+++ b/odcsim-core/src/main/kotlin/com/atlarge/odcsim/coroutines/Behavior.kt
@@ -28,9 +28,10 @@ import com.atlarge.odcsim.ActorContext
 import com.atlarge.odcsim.Behavior
 import com.atlarge.odcsim.DeferredBehavior
 import com.atlarge.odcsim.Signal
-import com.atlarge.odcsim.internal.SuspendingBehaviorContext
+import com.atlarge.odcsim.internal.SuspendingActorContextImpl
 import com.atlarge.odcsim.internal.SuspendingBehaviorImpl
 import kotlin.coroutines.Continuation
+import kotlin.coroutines.CoroutineContext
 import kotlin.coroutines.suspendCoroutine
 
 /**
@@ -65,7 +66,7 @@ fun <T : Any> Behavior.Companion.suspending(block: suspend (SuspendingActorConte
  *
  * @param T The shape of the messages the actor accepts.
  */
-interface SuspendingActorContext<T : Any> : ActorContext<T> {
+interface SuspendingActorContext<T : Any> : ActorContext<T>, CoroutineContext.Element {
     /**
      * Suspend execution of the active coroutine to wait for a message of type [T] to be received in the actor's
      * mailbox. During suspension, incoming signals will be marked unhandled.
@@ -81,6 +82,12 @@ interface SuspendingActorContext<T : Any> : ActorContext<T> {
      * @return The [Signal] that has been received.
      */
     suspend fun receiveSignal(): Signal
+
+    /**
+     * A key to provide access to the untyped [SuspendingActorContext] via [CoroutineContext] for suspending methods
+     * running inside a [SuspendingBehavior].
+     */
+    companion object Key : CoroutineContext.Key<SuspendingActorContext<*>>
 }
 
 /**
@@ -91,7 +98,7 @@ interface SuspendingActorContext<T : Any> : ActorContext<T> {
 suspend fun <T : Any, U> suspendWithBehavior(block: (Continuation<U>, () -> Behavior<T>) -> Behavior<T>): U =
     suspendCoroutine { cont ->
         @Suppress("UNCHECKED_CAST")
-        val ctx = cont.context[SuspendingBehaviorContext] as? SuspendingBehaviorContext<T>
+        val ctx = cont.context[SuspendingActorContext] as? SuspendingActorContextImpl<T>
             ?: throw UnsupportedOperationException("Coroutine does not run inside SuspendingBehavior")
         ctx.become(block(cont) { ctx.behavior })
     }
diff --git a/odcsim-core/src/main/kotlin/com/atlarge/odcsim/internal/Coroutines.kt b/odcsim-core/src/main/kotlin/com/atlarge/odcsim/internal/Coroutines.kt
index d8c3e8fc..7f2d39bc 100644
--- a/odcsim-core/src/main/kotlin/com/atlarge/odcsim/internal/Coroutines.kt
+++ b/odcsim-core/src/main/kotlin/com/atlarge/odcsim/internal/Coroutines.kt
@@ -41,15 +41,10 @@ import kotlin.coroutines.resume
 import kotlin.coroutines.startCoroutine
 
 /**
- * The interface that is exposed from the [CoroutineContext] and provides control over the [SuspendingBehavior]
- * instance.
+ * This interface exposes internal functionality provided by [SuspendingBehaviorImpl] on [SuspendingActorContext] to
+ * control the active behavior of the coroutine.
  */
-interface SuspendingBehaviorContext<T : Any> : CoroutineContext.Element {
-    /**
-     * The [ActorContext] in which the actor currently runs.
-     */
-    val context: SuspendingActorContext<T>
-
+interface SuspendingActorContextImpl<T : Any> : SuspendingActorContext<T> {
     /**
      * The current active behavior
      */
@@ -61,12 +56,6 @@ interface SuspendingBehaviorContext<T : Any> : CoroutineContext.Element {
      * @param next The behavior to replace the current behavior with.
      */
     fun become(next: Behavior<T>)
-
-    /**
-     * This key provides users access to an untyped actor context in case the coroutine runs inside a
-     * [SuspendingBehavior].
-     */
-    companion object Key : CoroutineContext.Key<SuspendingBehaviorContext<*>>
 }
 
 /**
@@ -75,7 +64,7 @@ interface SuspendingBehaviorContext<T : Any> : CoroutineContext.Element {
  * This implementation uses the fact that each actor is thread-safe (as it processes its mailbox sequentially).
  */
 internal class SuspendingBehaviorImpl<T : Any>(actorContext: ActorContext<T>, initialBehavior: SuspendingBehavior<T>) :
-        ReceivingBehavior<T>(), SuspendingActorContext<T>, SuspendingBehaviorContext<T> {
+        ReceivingBehavior<T>(), SuspendingActorContextImpl<T> {
     /**
      * The next behavior to use.
      */
@@ -128,15 +117,13 @@ internal class SuspendingBehaviorImpl<T : Any>(actorContext: ActorContext<T>, in
         }
     }
 
-    override val context: SuspendingActorContext<T> get() = this
-
     override val behavior: Behavior<T> get() = interpreter.behavior
 
     override fun become(next: Behavior<T>) {
         interpreter.become(actorContext, next)
     }
 
-    override val key: CoroutineContext.Key<*> = SuspendingBehaviorContext.Key
+    override val key: CoroutineContext.Key<*> = SuspendingActorContext.Key
 
     /**
      * Start the suspending behavior.
-- 
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