Removed ReplaySubject Subscriber accounting

The behaviour of Apple's stock Subjects suggests that Subscriber accounting (to prevent duplicate subscriptions of the same Subscriber) is the responsibility of the Subscriber itself – not the Subjects they're subscribed to. Thanks for the heads-up @jasdev!
tcldr · May 8, 2020 · fc3bc4d · fc3bc4d
1 parent 9b3514f
commit fc3bc4d
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Showing 2 changed files with 3 additions and 25 deletions.
diff --git a/Sources/Entwine/Operators/ReplaySubject.swift b/Sources/Entwine/Operators/ReplaySubject.swift
@@ -35,8 +35,6 @@ public final class ReplaySubject<Output, Failure: Error> {
     typealias Sink = AnySubscriber<Output, Failure>
 
     private var subscriptions = [ReplaySubjectSubscription<Sink>]()
-    private var subscriberIdentifiers = Set<CombineIdentifier>()
-
     private var replayValues: ReplaySubjectValueBuffer<Output>
     private var completion: Subscribers.Completion<Failure>?
 
@@ -55,32 +53,13 @@ public final class ReplaySubject<Output, Failure: Error> {
 extension ReplaySubject: Publisher {
 
     public func receive<S : Subscriber>(subscriber: S) where Failure == S.Failure, Output == S.Input {
-
-        guard !subscriberIdentifiers.contains(subscriber.combineIdentifier) else {
-            subscriber.receive(subscription: Subscriptions.empty)
-            return
-        }
-
         let subscriberIdentifier = subscriber.combineIdentifier
-
         let subscription = ReplaySubjectSubscription(sink: AnySubscriber(subscriber))
-
-        // we use seperate collections for identifiers and subscriptions
-        // to improve performance of identifier lookups and to keep the
-        // order in which subscribers are signalled to be in the order that
-        // they intially subscribed.
-
-        subscriberIdentifiers.insert(subscriberIdentifier)
         subscriptions.append(subscription)
-
         subscription.cleanupHandler = { [weak self] in
-
-            guard let self = self else { return }
-
-            if let index = self.subscriptions.firstIndex(where: { subscriberIdentifier == $0.subscriberIdentifier }) {
-                self.subscriberIdentifiers.remove(subscriberIdentifier)
-                self.subscriptions.remove(at: index)
-            }
+            let firstIndex = self?.subscriptions.firstIndex { subscriberIdentifier == $0.subscriberIdentifier }
+            guard let index = firstIndex else { return }
+            self?.subscriptions.remove(at: index)
         }
         subscriber.receive(subscription: subscription)
         subscription.replayInputs(replayValues.buffer, completion: completion)

diff --git a/Tests/EntwineTests/ReplaySubjectTests.swift b/Tests/EntwineTests/ReplaySubjectTests.swift
@@ -169,7 +169,6 @@ final class ReplaySubjectTests: XCTestCase {
         scheduler.schedule(after: 600) { subject.send(0) }
         scheduler.schedule(after: 700) { subject.send(completion: .finished) }
 
-
         scheduler.resume()
 
         let expected1: TestSequence<Int, Never> = [