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Clear transient disconnect timeouts per spec
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Based on the spec referenced in 20f21c7.

Resolves #48.
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@lawrence-forooghian
lawrence-forooghian committed Nov 6, 2024
1 parent cb4a8cb commit 87157b6
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Showing 3 changed files with 239 additions and 21 deletions.
80 changes: 74 additions & 6 deletions Sources/AblyChat/RoomLifecycleManager.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -301,9 +301,10 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
/// A contributor state change is considered handled once the manager has performed all of the side effects that it will perform as a result of receiving this state change. Specifically, once:
///
/// - the manager has recorded all pending discontinuity events provoked by the state change (you can retrieve these using ``testsOnly_pendingDiscontinuityEventsForContributor(at:)``)
/// - the manager has performed all status changes provoked by the state change
/// - the manager has performed all status changes provoked by the state change (this does _not_ include the case in which the state change provokes the creation of a transient disconnect timeout which subsequently provokes a status change; use ``testsOnly_subscribeToHandledTransientDisconnectTimeouts()`` to find out about those)
/// - the manager has performed all contributor actions provoked by the state change, namely calls to ``RoomLifecycleContributorChannel.detach()`` or ``RoomLifecycleContributor.emitDiscontinuity(_:)``
/// - the manager has recorded all transient disconnect timeouts provoked by the state change (you can retrieve this information using ``testsOnly_hasTransientDisconnectTimeout(for:) or ``testsOnly_idOfTransientDisconnectTimeout(for:)``)
/// - the manager has performed all transient disconnect timeout cancellations provoked by the state change (you can retrieve this information using ``testsOnly_hasTransientDisconnectTimeout(for:) or ``testsOnly_idOfTransientDisconnectTimeout(for:)``)
internal func testsOnly_subscribeToHandledContributorStateChanges() -> Subscription<ARTChannelStateChange> {
let subscription = Subscription<ARTChannelStateChange>(bufferingPolicy: .unbounded)
stateChangeHandledSubscriptions.append(subscription)
Expand All @@ -318,9 +319,28 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
contributorAnnotations[contributor].hasTransientDisconnectTimeout
}

internal var testsOnly_hasTransientDisconnectTimeoutForAnyContributor: Bool {
contributors.contains { testsOnly_hasTransientDisconnectTimeout(for: $0) }
}

internal func testsOnly_idOfTransientDisconnectTimeout(for contributor: Contributor) -> UUID? {
contributorAnnotations[contributor].transientDisconnectTimeout?.id
}

// TODO: clean up old subscriptions (https://github.com/ably-labs/ably-chat-swift/issues/36)
/// Supports the ``testsOnly_subscribeToHandledTransientDisconnectTimeouts()`` method.
private var transientDisconnectTimeoutHandledSubscriptions: [Subscription<UUID>] = []

/// Returns a subscription which emits the IDs of the transient disconnect timeouts that have been handled by the manager.
///
/// A transient disconnect timeout is considered handled once the manager has performed all of the side effects that it will perform as a result of creating this timeout. Specifically, once:
///
/// - the manager has performed all status changes provoked by the completion of this timeout (which may be none, if the timeout gets cancelled)
internal func testsOnly_subscribeToHandledTransientDisconnectTimeouts() -> Subscription<UUID> {
let subscription = Subscription<UUID>(bufferingPolicy: .unbounded)
transientDisconnectTimeoutHandledSubscriptions.append(subscription)
return subscription
}
#endif

/// Implements CHA-RL4b’s contributor state change handling.
Expand Down Expand Up @@ -364,11 +384,16 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {

contributorAnnotations[contributor].pendingDiscontinuityEvents.append(reason)
}
} else if status != .attached {
if await (contributors.async.map { await $0.channel.state }.allSatisfy { $0 == .attached }) {
// CHA-RL4b8
logger.log(message: "Now that all contributors are ATTACHED, transitioning room to ATTACHED", level: .info)
changeStatus(to: .attached)
} else {
// CHA-RL4b10
clearTransientDisconnectTimeouts(for: contributor)

if status != .attached {
if await (contributors.async.map { await $0.channel.state }.allSatisfy { $0 == .attached }) {
// CHA-RL4b8
logger.log(message: "Now that all contributors are ATTACHED, transitioning room to ATTACHED", level: .info)
changeStatus(to: .attached)
}
}
}
case .failed:
Expand All @@ -379,6 +404,7 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
preconditionFailure("FAILED state change event should have a reason")
}

clearTransientDisconnectTimeouts()
changeStatus(to: .failed(error: reason))

// TODO: CHA-RL4b5 is a bit unclear about how to handle failure, and whether they can be detached concurrently (asked in https://github.com/ably/specification/pull/200/files#r1777471810)
Expand All @@ -398,6 +424,8 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
preconditionFailure("SUSPENDED state change event should have a reason")
}

clearTransientDisconnectTimeouts()

changeStatus(to: .suspended(error: reason))
}
case .attaching:
Expand All @@ -411,10 +439,20 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
try await clock.sleep(timeInterval: 5)
} catch {
logger.log(message: "Transient disconnect timeout \(transientDisconnectTimeout.id) for \(contributor) was interrupted, error \(error)", level: .debug)

#if DEBUG
emitTransientDisconnectTimeoutHandledEventForTimeoutWithID(transientDisconnectTimeout.id)
#endif

return
}
logger.log(message: "Transient disconnect timeout \(transientDisconnectTimeout.id) for \(contributor) completed", level: .debug)
contributorAnnotations[contributor].transientDisconnectTimeout = nil
changeStatus(to: .attachingDueToContributorStateChange(error: stateChange.reason))

#if DEBUG
emitTransientDisconnectTimeoutHandledEventForTimeoutWithID(transientDisconnectTimeout.id)
#endif
}
}
default:
Expand All @@ -429,6 +467,31 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
#endif
}

#if DEBUG
private func emitTransientDisconnectTimeoutHandledEventForTimeoutWithID(_ id: UUID) {
logger.log(message: "Emitting transient disconnect timeout handled event for \(id)", level: .debug)
for subscription in transientDisconnectTimeoutHandledSubscriptions {
subscription.emit(id)
}
}
#endif

private func clearTransientDisconnectTimeouts(for contributor: Contributor) {
guard let transientDisconnectTimeout = contributorAnnotations[contributor].transientDisconnectTimeout else {
return
}

logger.log(message: "Clearing transient disconnect timeout \(transientDisconnectTimeout.id) for \(contributor)", level: .debug)
transientDisconnectTimeout.task?.cancel()
contributorAnnotations[contributor].transientDisconnectTimeout = nil
}

private func clearTransientDisconnectTimeouts() {
for contributor in contributors {
clearTransientDisconnectTimeouts(for: contributor)
}
}

// MARK: - Operation handling

/// Whether the room lifecycle manager currently has a room lifecycle operation in progress.
Expand Down Expand Up @@ -614,6 +677,9 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
}
}

// CHA-RL1g3
clearTransientDisconnectTimeouts()

// CHA-RL1g1
changeStatus(to: .attached)

Expand Down Expand Up @@ -684,6 +750,7 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
}

// CHA-RL2e
clearTransientDisconnectTimeouts()
changeStatus(to: .detaching(detachOperationID: operationID))

// CHA-RL2f
Expand Down Expand Up @@ -774,6 +841,7 @@ internal actor RoomLifecycleManager<Contributor: RoomLifecycleContributor> {
}

// CHA-RL3l
clearTransientDisconnectTimeouts()
changeStatus(to: .releasing(releaseOperationID: operationID))

// CHA-RL3d
Expand Down
4 changes: 2 additions & 2 deletions Tests/AblyChatTests/Mocks/MockSimpleClock.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ actor MockSimpleClock: SimpleClock {

enum SleepBehavior {
case success
case fromFunction(@Sendable () async -> Void)
case fromFunction(@Sendable () async throws -> Void)
}

init(sleepBehavior: SleepBehavior? = nil) {
Expand All @@ -32,7 +32,7 @@ actor MockSimpleClock: SimpleClock {
case .success:
break
case let .fromFunction(function):
await function()
try await function()
}
}
}
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