rabbah commented on a change in pull request #3202: Support action
continuations in the controller
URL:
https://github.com/apache/incubator-openwhisk/pull/3202#discussion_r165245124
##########
File path:
core/controller/src/main/scala/whisk/core/controller/actions/PrimitiveActions.scala
##########
@@ -139,6 +199,356 @@ protected[actions] trait PrimitiveActions {
}
}
+ /**
+ * Mutable cumulative accounting of what happened during the execution of a
composition.
+ *
+ * Compositions are aborted if the number of action invocations exceeds a
limit.
+ * The permitted max is n component invocations plus 2n+1 conductor
invocations (where n is the actionSequenceLimit).
+ * The max is chosen to permit a sequence with up to n primitive actions.
+ *
+ * NOTE:
+ * A sequence invocation counts as one invocation irrespective of the number
of action invocations in the sequence.
+ * If one component of a composition is also a composition, the caller and
callee share the same accounting object.
+ * The counts are shared between callers and callees so the limit applies
globally.
+ *
+ * @param components the current count of component actions already invoked
+ * @param conductors the current count of conductor actions already invoked
+ */
+ private case class CompositionAccounting(var components: Int = 0, var
conductors: Int = 0)
+
+ /**
+ * A mutable session object to keep track of the execution of one
composition.
+ *
+ * NOTE:
+ * The session object is not shared between callers and callees.
+ * A callee has a reference to the session object for the caller.
+ * This permits the callee to return to the caller when done.
+ *
+ * @param activationId the activationId for the composition (ie the
activation record for the composition)
+ * @param start the start time for the composition
+ * @param action the conductor action responsible for the execution of the
composition
+ * @param cause the cause of the composition (activationId of the enclosing
sequence or composition if any)
+ * @param duration the "user" time so far executing the composition (sum of
durations for
+ * all actions invoked so far which is different from the total time
spent executing the composition)
+ * @param maxMemory the maximum memory annotation observed so far for the
conductor action and components
+ * @param state the json state object to inject in the parameter object of
the next conductor invocation
+ * @param accounting the global accounting object used to abort compositions
requiring too many action invocations
+ * @param logs a mutable buffer that is appended with new activation ids as
the composition unfolds
+ * (in contrast with sequences, the logs of a hierarchy of
compositions is not flattened)
+ * @param caller the session object for the parent composition (caller) if
any
+ * @param result a placeholder for returning the result of the composition
invocation (blocking invocation only)
+ */
+ private case class Session(activationId: ActivationId,
+ start: Instant,
+ action: ExecutableWhiskActionMetaData,
+ cause: Option[ActivationId],
+ var duration: Long,
+ var maxMemory: Int,
+ var state: Option[JsObject],
+ accounting: CompositionAccounting,
+ logs: Buffer[ActivationId],
+ caller: Option[Session],
+ result: Option[Promise[Either[ActivationId,
WhiskActivation]]])
+
+ /**
+ * A method that knows how to invoke a composition.
+ *
+ * The method instantiates the session object for the composition, invokes
the conductor action for the composition,
+ * and waits for the composition result (resulting activation) if the
invocation is blocking (up to timeout).
+ *
+ * @param user the identity invoking the action
+ * @param action the conductor action to invoke for the composition
+ * @param payload the dynamic arguments for the activation
+ * @param waitForResponse if not empty, wait upto specified duration for a
response (this is used for blocking activations)
+ * @param cause the activation id that is responsible for this
invoke/activation
+ * @param caller the session object for the caller if any
+ * @param transid a transaction id for logging
+ * @return a promise that completes with one of the following successful
cases:
+ * Right(WhiskActivation) if waiting for a response and response
is ready within allowed duration,
+ * Left(ActivationId) if not waiting for a response, or allowed
duration has elapsed without a result ready
+ * or an error
+ */
+ private def invokeComposition(
+ user: Identity,
+ action: ExecutableWhiskActionMetaData,
+ payload: Option[JsObject],
+ waitForResponse: Option[FiniteDuration],
+ cause: Option[ActivationId],
+ caller: Option[Session] = None)(implicit transid: TransactionId):
Future[Either[ActivationId, WhiskActivation]] = {
+
+ val session = Session(
+ activationId = activationIdFactory.make(),
+ start = Instant.now(Clock.systemUTC()),
+ action,
+ cause,
+ duration = 0,
+ maxMemory = action.limits.memory.megabytes,
+ state = None,
+ accounting = caller.map { _.accounting
}.getOrElse(CompositionAccounting()), // share accounting with caller
+ logs = Buffer.empty,
+ caller,
+ result = waitForResponse.map { _ =>
+ Promise[Either[ActivationId, WhiskActivation]]() // placeholder for
result if blocking invoke
+ })
+
+ invokeConductor(user, payload, session)
+
+ // is caller waiting for the result of the activation?
+ waitForResponse
+ .map { timeout =>
+ // handle timeout
+ session.result.head.future
+ .withAlternativeAfterTimeout(timeout,
Future.successful(Left(session.activationId)))
+ }
+ .getOrElse {
+ // no, return the session id
+ Future.successful(Left(session.activationId))
+ }
+ }
+
+ /**
+ * A method that knows how to handle a conductor invocation.
+ *
+ * This method prepares the payload and invokes the conductor action.
+ * It parses the result and extracts the name of the next component action
if any.
+ * It either invokes the desired component action or completes the
composition invocation.
+ * It also checks the invocation counts against the limits.
+ *
+ * @param user the identity invoking the action
+ * @param payload the dynamic arguments for the activation
+ * @param session the session object for this composition
+ * @param transid a transaction id for logging
+ */
+ private def invokeConductor(user: Identity, payload: Option[JsObject],
session: Session)(
+ implicit transid: TransactionId) = {
+
+ if (session.accounting.conductors > 2 * actionSequenceLimit) {
+ // composition is too long
+ val response = ActivationResponse.applicationError(compositionIsTooLong)
+ completeAppActivation(user, session, response)
+ } else {
+ // inject state into payload if any
+ val params = session.state
+ .map { state =>
+ Some(JsObject(payload.getOrElse(JsObject()).fields ++ state.fields))
+ }
+ .getOrElse(payload)
+
+ // invoke conductor action
+ session.accounting.conductors += 1
+ val response =
+ invokeSimpleAction(
+ user,
+ session.action,
+ params,
+ Some(session.action.limits.timeout.duration + 1.minute), // wait for
result
Review comment:
i'd use
```
...,
waitForResponse = ...,
cause = ...)
```
in addition to/vs the comment.
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