Add a recurring collect function and associated unit tests #619

Qata · 2018-03-04T23:37:52Z

Checklist

Updated CHANGELOG.md.

This PR introduces a new function that collects values from self and delivers them to the subscriber every interval.
Solves issue #614.

NachoSoto

Nice!

mdiep · 2018-03-05T14:34:44Z

Sources/Signal.swift

+	///
+	/// - note: If the input signal terminates, the returned signal will
+	///         terminate immediately without forwarding the values
+	///	        currently being accumulated.


In the spirit of #605, maybe there should be an option to forward the values first?

Good point!

After looking into this I can't find a way to make it work consistently, given:
When you complete the Signal when you'd expect is for it to still delay up to the supplied interval, and only then deliver the values followed immediately by a completed event.
In the event of interrupted or failed, you'd need to forward those events immediately, so the values would also need to be delivered immediately.
This would probably create tricky behaviour for a lot of people consuming this function, since you'd expect values to be delivered exactly interval apart (or a multiple of interval if you're ignoring when empty).

So should it only not discard in the case of .completed?

Yeah, values should only be forwarded in the case of .completed.

mdiep · 2018-03-05T14:36:09Z

Sources/Signal.swift

+	///
+	/// - returns: A signal that sends all values that are sent from `self` at
+	///            `interval` seconds apart.
+	public func chunk(_ interval: DispatchTimeInterval, on scheduler: DateScheduler, ignoreEmptyChunks: Bool = false) -> Signal<[Value], Error> {


I'm very hesitant to introduce complete new operator names. I think our grouping of operators by base name has been very successful and would like for us to continue it.

While this is similar to debounce/throttle, I'm not sure it's really throttling them. I don't think a throttle is always regular.

I think this could fit under collect though.

func collect(every interval: DispatchTimeInterval, on scheduler: DataScheduler) -> Signal<[Value], Error> {

collect serves as the base name for operators that go from A to [A].

Thoughts @ReactiveCocoa/reactiveswift?

Oh yep I forgot to say that bikeshedding the name is very welcome, I have no attachments to the one I chose.

mdiep · 2018-03-20T12:46:41Z

CHANGELOG.md

@@ -1,6 +1,7 @@
 # master
 *Please add new entries at the top.*

+1. New method `chunk(_:on:ignoreEmptyChunks:)` which delivers all values that occurred during a time chunk (#619, kudos to @Qata)


This needs to be updated.

mdiep · 2018-03-20T12:56:35Z

Sources/Signal.swift

+	///
+	/// - note: If the input signal terminates, the returned signal will
+	///         terminate immediately without forwarding the values
+	///	        currently being accumulated.


Yeah, values should only be forwarded in the case of .completed.

mdiep · 2018-03-20T12:58:21Z

Sources/Signal.swift

+	///
+	/// - returns: A signal that sends all values that are sent from `self` at
+	///            `interval` seconds apart.
+	public func collect(_ interval: DispatchTimeInterval, on scheduler: DateScheduler, ignoreWhenEmpty: Bool = false) -> Signal<[Value], Error> {


We've standardized on skip for values that aren't sent. We should use that here.

mdiep · 2018-03-20T12:58:52Z

Sources/Signal.swift

+	///
+	/// - returns: A signal that sends all values that are sent from `self` at
+	///            `interval` seconds apart.
+	public func collect(_ interval: DispatchTimeInterval, on scheduler: DateScheduler, ignoreWhenEmpty: Bool = false) -> Signal<[Value], Error> {


I think we should name the interval parameter. Maybe every:?

mdiep · 2018-03-20T13:51:40Z

Sources/Event.swift

+				}
+				if let values = currentValues {
+					action(.value(values))
+				}


I think this could be better written like so:

let currentValues = values.swap([]) if !currentValues.isEmpty { action(.value(currentValues)) }

mdiep · 2018-03-20T14:02:22Z

Sources/Event.swift

+				if let values = currentValues {
+					action(.value(values))
+				}
+			})


This should use trailing closure syntax.

Qata · 2018-03-22T03:14:45Z

@mdiep Issues addressed 👍

mdiep · 2018-03-28T13:23:34Z

I'll try to get to this in the next day or two

mdiep · 2018-03-30T13:17:53Z

Sources/Event.swift

+				case .completed:
+					let currentValues = values.swap([])
+					if !discardsWhenCompleted, !(currentValues.isEmpty && skipEmpty) {
+						d.inner = scheduler.schedule(after: lastDelivered.addingTimeInterval(interval)) {


This schedule call makes me a little uneasy. It's difficult to reason about how this will interact with the other scheduling call. (e.g. it's possible that the above schedule could run in-between this values.swap and this scheduler.schedule).

I think we should solve this by removing this schedule and sending the complete through the top schedule. This would be best done by adding a CollectEveryState struct and putting that inside an Atomic instead of a Atomic<[Value]>.

Something like this:

state CollectEveryState<Value> { var skipEmpty: Bool var values: [Value] = [] var isCompleted: Bool var hasValues: Bool { return !values.isEmpty || !skipEmpty } func collect() -> [Value]? { if !hasValues { return nil } defer { values.removeAll() } return values } }

That should clean up the implementation a bit too, which is nice.

@mdiep Done 👍

Qata · 2018-04-04T01:50:58Z

Sources/Event.swift

+					action(.value(currentValues))
+				}
+				if isCompleted {
+					action(.completed)


@mdiep Should I call d.dispose() manually here?

Yes, I think so. Otherwise the timer would continue firing.

d is disposed already as part of the lifetime observer, so repeating it here is not necessary.

mdiep · 2018-04-04T12:12:17Z

Sources/Event.swift

+					action(.value(currentValues))
+				}
+				if isCompleted {
+					action(.completed)


Yes, I think so. Otherwise the timer would continue firing.

mdiep · 2018-04-04T12:14:14Z

Sources/Event.swift

+
+	internal static func collect(every interval: DispatchTimeInterval, on scheduler: DateScheduler, skipEmpty: Bool, discardsWhenCompleted: Bool) -> Transformation<[Value], Error> {
+		return { action, lifetime in
+			let values = Atomic<CollectEveryState<Value>>(.init(skipEmpty: skipEmpty))


Could we also rename values to state since we have to add the dispose call below?

mdiep · 2018-04-04T12:15:37Z

I think this cleaned up rather nicely. 👏 After the minor fixes noted above, we should be good to go.

mdiep · 2018-04-04T12:16:14Z

Sources/Event.swift

@@ -861,6 +861,63 @@ extension Signal.Event {
 			}
 		}
 	}
+
+	internal static func collect(every interval: DispatchTimeInterval, on scheduler: DateScheduler, skipEmpty: Bool, discardsWhenCompleted: Bool) -> Transformation<[Value], Error> {


Oh, let's make this discardWhenCompleted (no s) since we're doing that in #605 as well.

mdiep · 2018-04-06T01:27:49Z

Unfortunately, the linux build is failing on CI and I don't see why. 😐

mdiep · 2018-04-06T01:36:02Z

This will need a merge now that #605 has been merged.

Qata · 2018-04-06T04:28:44Z

@andersio Could you have a look when you have time

andersio

LGTM otherwise

andersio · 2018-04-15T17:27:59Z

Sources/Event.swift

+					action(.value(currentValues))
+				}
+				if isCompleted {
+					action(.completed)


d is disposed already as part of the lifetime observer, so repeating it here is not necessary.

Qata · 2018-04-16T00:34:51Z

@andersio Done 👍

mdiep · 2018-04-16T12:34:42Z

Thanks @Qata!

Qata added 2 commits March 5, 2018 10:35

Add the chunk function and associated unit tests

16a620e

Update CHANGELOG.md

7322bf9

NachoSoto reviewed Mar 5, 2018

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mdiep reviewed Mar 5, 2018

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Qata added 2 commits March 9, 2018 15:11

Change name of new operator

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Change modify to return value

45a49b9

Qata changed the title ~~Add the chunk function and associated unit tests~~ Add a recurring collect function and associated unit tests Mar 9, 2018

mdiep requested changes Mar 20, 2018

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mdiep requested a review from andersio March 20, 2018 14:19

Qata added 2 commits March 22, 2018 14:03

Address review comments

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Update documentation

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mdiep requested changes Mar 30, 2018

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Address review comment

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Qata commented Apr 4, 2018

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mdiep requested changes Apr 4, 2018

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Qata added 2 commits April 6, 2018 10:33

Change discardsWhenCompleted to discardWhenCompleted

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Change variable naming

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mdiep approved these changes Apr 6, 2018

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Add Dispatch import

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Qata added 3 commits April 6, 2018 12:05

Remove tests

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Merge branch 'master' into proposal/614

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Add Dispatch import

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mdiep approved these changes Apr 6, 2018

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andersio approved these changes Apr 15, 2018

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andersio added this to the 4.0 milestone Apr 15, 2018

Update Event.swift

710540e

mdiep merged commit 34a7750 into ReactiveCocoa:master Apr 16, 2018

andersio mentioned this pull request May 26, 2020

Add bottlenecked(_:on:). #547

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Add a recurring collect function and associated unit tests #619

Add a recurring collect function and associated unit tests #619

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Add a recurring collect function and associated unit tests #619

Add a recurring collect function and associated unit tests #619

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Qata commented Mar 4, 2018 • edited Loading

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