mirror of
https://github.com/sudosylabs/vnidrop.git
synced 2026-08-05 02:29:55 +02:00
cdricms
22b93ce94e
iOS suspends the process on backgrounding, freezing the core's network threads so in-flight transfers stall and never fire notifications. Hold a UIApplication background-task assertion (BackgroundActivityController) while transfers/shares are active so iOS grants its grace window — long enough to finish and notify. Released on foreground, on completion, or on expiration. No UIBackgroundModes added (keeps App Store validation clean); macOS is a no-op since it already runs unfocused. Add a localized iOS-only Settings notice explaining the platform limit so it doesn't read as a bug.
78 lines
2.9 KiB
Swift
78 lines
2.9 KiB
Swift
import Combine
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import Foundation
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#if os(iOS)
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import UIKit
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#endif
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/// Keeps the Rust core alive across the app moving to the background, within the
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/// bounds Apple actually allows for a serverless P2P transfer app.
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///
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/// iOS suspends the whole process (freezing the core's network threads) shortly
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/// after the app leaves the foreground. When a transfer or share is active we
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/// take a `UIApplication` background-task assertion so iOS grants its finite
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/// grace window — long enough for an in-flight transfer to finish streaming and
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/// for its completion/failure notification to fire. There is no App-Store-legal
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/// mechanism to keep serving or receiving *indefinitely* while backgrounded, and
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/// `BGTaskScheduler` wake-ups run only opportunistically and cannot detect an
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/// incoming peer connection, so they are deliberately not used here.
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///
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/// macOS does not suspend the process on focus loss, so this is a no-op there and
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/// the core keeps running normally.
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@MainActor
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final class BackgroundActivityController {
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private let repository: CoreRepository
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init(repository: CoreRepository) {
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self.repository = repository
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}
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#if os(iOS)
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private var assertionId: UIBackgroundTaskIdentifier = .invalid
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private var idleCancellable: AnyCancellable?
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/// The app moved to the background. Hold the process open while there is live
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/// work; release as soon as it drains, on return to foreground, or when iOS
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/// ends the grace window (whichever comes first).
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func didEnterBackground() {
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guard assertionId == .invalid, hasActiveWork else { return }
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assertionId = UIApplication.shared.beginBackgroundTask(withName: "vnidrop.transfer") { [weak self] in
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// Expiration handler: iOS is reclaiming the window; end cleanly to
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// avoid the watchdog terminating the app.
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self?.endAssertion()
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}
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// Release the assertion the moment work finishes instead of holding it for
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// the full window (battery, and it lets the process suspend sooner). Events
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// still deliver on the main actor while the window is open, so the core's
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// active counts drop here when a transfer completes.
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idleCancellable = repository.statePublisher
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.map { ($0.status?.activeTransfers ?? 0) == 0 && ($0.status?.activeShares ?? 0) == 0 }
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.removeDuplicates()
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.sink { [weak self] idle in
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if idle { self?.endAssertion() }
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}
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}
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/// The app returned to the foreground; the process is live again, so drop any
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/// held assertion.
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func didBecomeForeground() {
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endAssertion()
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}
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private var hasActiveWork: Bool {
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let status = repository.state.status
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return (status?.activeTransfers ?? 0) > 0 || (status?.activeShares ?? 0) > 0
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}
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private func endAssertion() {
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idleCancellable?.cancel()
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idleCancellable = nil
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guard assertionId != .invalid else { return }
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UIApplication.shared.endBackgroundTask(assertionId)
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assertionId = .invalid
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}
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#else
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func didEnterBackground() {}
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func didBecomeForeground() {}
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#endif
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}
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