[GitHub] [openwhisk] rabbah commented on a change in pull request #4624: Combines active ack and slot release when both are available.

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rabbah commented on a change in pull request #4624: Combines active ack and slot release when both are available.
URL: https://github.com/apache/openwhisk/pull/4624#discussion_r324425930
 
 

 ##########
 File path: common/scala/src/main/scala/org/apache/openwhisk/core/connector/Message.scala
 ##########
 @@ -64,43 +64,34 @@ case class ActivationMessage(override val transid: TransactionId,
   def causedBySequence: Boolean = cause.isDefined
 }
 
-object ActivationMessage extends DefaultJsonProtocol {
-
-  def parse(msg: String) = Try(serdes.read(msg.parseJson))
-
-  private implicit val fqnSerdes = FullyQualifiedEntityName.serdes
-  implicit val serdes = jsonFormat11(ActivationMessage.apply)
-}
-
 /**
  * Message that is sent from the invoker to the controller after action is completed or after slot is free again for
  * new actions.
  */
 abstract class AcknowledegmentMessage(private val tid: TransactionId) extends Message {
   override val transid: TransactionId = tid
-  override def serialize: String = {
-    AcknowledegmentMessage.serdes.write(this).compactPrint
-  }
+  override def serialize: String = AcknowledegmentMessage.serdes.write(this).compactPrint
+  def toJson: JsValue
 }
 
 /**
- * This message is sent from the invoker to the controller, after the slot of an invoker that has been used by the
- * current action, is free again (after log collection)
+ * This message is sent from an invoker to the controller, after the resource slot in the invoke, used by the
+ * corresponding activation, is free again (i.e., after log collection). In some cases, the activation result is
+ * ready and the slot is freed at the same time. In such cases, the completion message carries the result as well.
+ * This is reflected by the of a Right() `response` and the param `result` is set to true.
+ * In some cases the `result` is true but the response is Left() if the message was too large for the message bus.
  */
 case class CompletionMessage(override val transid: TransactionId,
-                             activationId: ActivationId,
-                             isSystemError: Boolean,
+                             response: Either[ActivationId, WhiskActivation],
+                             result: Boolean, // true iff the message is a combined active ack and slot released
 
 Review comment:
   When `result` is false:
   1. `Left`: this is the current situation and can occur during split phase notification
   1. `Right`: cannot happen, would be a bug (this should be an active ack instead)
   
   When `result` is true:
   1. `Right`: this combines the active ack and slot release and occurs during system generate activations for failure scenarios
   2. `Left`: like the previous case but occurs when the message is too large to cross the event bus and the sender converts the Right to a Left.
   
   Since there are 3 possible scenarios, `Either` by itself is not enough, and so I chose to encode the extra bit with `result` as a boolean.

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