<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On Aug 24, 2017, at 3:15 PM, Thomas <<a href="mailto:tclementdev@free.fr" class="">tclementdev@free.fr</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On 24 Aug 2017, at 23:47, Adam Kemp <<a href="mailto:adam.kemp@apple.com" class="">adam.kemp@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Aug 24, 2017, at 1:05 PM, Thomas via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" class=""><div class=""><br class="Apple-interchange-newline">On 24 Aug 2017, at 21:48, Marc Schlichte <<a href="mailto:marc.schlichte@googlemail.com" class="">marc.schlichte@googlemail.com</a>> wrote:</div><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div class=""><div class=""><br class=""></div>Yes, I think it is mandatory that we continue on the callers queue after an `await ` on some actor method.</div><div class=""><br class=""></div><div class="">If you `await` on a non-actor-method though, you would have to changes queues manually if needed.</div><div class=""><br class=""></div><div class="">Any `actor` should have a `let actorQueue: DispatchQueue` property so that we can call in these cases:</div><div class=""><br class=""></div><div class="">```await actorQueue.asyncCoroutine()``` as mentioned in the manifesto.</div></div></div></blockquote><br class=""></div><div style="font-family: Helvetica; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">Wouldn't that be really confusing though? That awaiting certain methods would bring us back to the actor's queue but awaiting others would require manual queue hopping? What if the compiler was to always generate the 'await actorQueue.asyncCoroutine()' queue hopping code after awaiting on an async/actor method?</div></div></blockquote></div><br class=""><div class="">Yes, it would be confusing. await should either always return to the same queue or never do it. Otherwise it’s even more error-prone. I see the actor feature as being just another demonstration of why solving the queue-hopping problem is important for async/await to be useful.</div></div></div></blockquote></div><br class=""><div class="">So the way a non "fire and forget" actor method would work is:</div><div class=""><br class=""></div><div class="">- the actor's queue is in a suspended state until the method returns, this is required so that messages sent to other actor methods are not processed (they're added to the queue)</div><div class="">- if the method body awaits on some other code, it automatically jumps back on the actor's queue after awaiting, regardless of the queue's suspension and content</div><div class="">- when the method returns, the actor's queue is resumed and pending messages can be processed (if any)</div><div class=""><br class=""></div></div></div></blockquote></div><br class=""><div class="">I don’t think await should cause the actor’s queue (or any queue) to be suspended. Actor methods should not block waiting for asynchronous things. That’s how you get deadlocks. If an actor method needs to be async then it should work just like any async method on the main queue: it unblocks the queue and allows other messages to be processed until it gets an answer.</div><div class=""><br class=""></div><div class="">You do have to be aware of the fact that things can happen in between an await and the next line of code, but conveniently these places are all marked for you. They all say “await”. :)</div></body></html>