Signal-iOS/SignalNSE/NotificationService.swift
2021-11-02 14:46:00 -07:00

249 lines
10 KiB
Swift

//
// Copyright (c) 2021 Open Whisper Systems. All rights reserved.
//
import UserNotifications
import SignalMessaging
import SignalServiceKit
// The lifecycle of the NSE looks something like the following:
// 1) App receives notification
// 2) System creates an instance of the extension class
// and calls `didReceive` in the background
// 3) Extension processes messages / displays whatever
// notifications it needs to
// 4) Extension notifies its work is complete by calling
// the contentHandler
// 5) If the extension takes too long to perform its work
// (more than 30s), it will be notified and immediately
// terminated
//
// Note that the NSE does *not* always spawn a new process to
// handle a new notification and will also try and process notifications
// in parallel. `didReceive` could be called twice for the same process,
// but it will always be called on different threads. It may or may not be
// called on the same instance of `NotificationService` as a previous
// notification.
//
// We keep a global `environment` singleton to ensure that our app context,
// database, logging, etc. are only ever setup once per *process*
let environment = NSEEnvironment()
let hasShownFirstUnlockError = AtomicBool(false)
class NotificationService: UNNotificationServiceExtension {
private typealias ContentHandler = (UNNotificationContent) -> Void
private var contentHandler = AtomicOptional<ContentHandler>(nil)
// MARK: -
private static let unfairLock = UnfairLock()
private static var _logTimer: OffMainThreadTimer?
private static var _nseCounter: Int = 0
private static func nseDidStart() -> Int {
unfairLock.withLock {
if DebugFlags.internalLogging,
_logTimer == nil {
_logTimer = OffMainThreadTimer(timeInterval: 1.0, repeats: true) { _ in
Logger.info("... memoryUsage: \(LocalDevice.memoryUsage)")
}
}
_nseCounter = _nseCounter + 1
return _nseCounter
}
}
private static func nseDidComplete() -> Int {
unfairLock.withLock {
_nseCounter = _nseCounter > 0 ? _nseCounter - 1 : 0
if _nseCounter == 0, _logTimer != nil {
_logTimer?.invalidate()
_logTimer = nil
}
return _nseCounter
}
}
// MARK: -
// This method is thread-safe.
func completeSilenty(timeHasExpired: Bool = false) {
let nseCount = Self.nseDidComplete()
guard let contentHandler = contentHandler.swap(nil) else {
if DebugFlags.internalLogging {
Logger.warn("No contentHandler, memoryUsage: \(LocalDevice.memoryUsage), nseCount: \(nseCount).")
}
Logger.flush()
return
}
let content = UNMutableNotificationContent()
let updatedBadgeCount: NSNumber?
if environment.hasAppContent, let nseContext = CurrentAppContext() as? NSEContext {
if !timeHasExpired {
// If we have time, we might as well get the current up-to-date badge count
let freshCount = databaseStorage.read { InteractionFinder.unreadCountInAllThreads(transaction: $0.unwrapGrdbRead) }
updatedBadgeCount = NSNumber(value: freshCount)
} else if let cachedBadgeCount = nseContext.desiredBadgeNumber.get() {
// If we don't have time to get a fresh count, let's use the cached count stored in our context
updatedBadgeCount = NSNumber(value: cachedBadgeCount)
} else {
// The context never set a badge count, let's leave things as-is:
updatedBadgeCount = nil
}
} else {
// We never set up an NSEContext. Let's leave things as-is:
updatedBadgeCount = nil
}
content.badge = updatedBadgeCount
if DebugFlags.internalLogging {
Logger.info("Invoking contentHandler, memoryUsage: \(LocalDevice.memoryUsage), nseCount: \(nseCount).")
}
Logger.flush()
contentHandler(content)
}
override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
// This should be the first thing we do.
environment.ensureAppContext()
// Detect and handle "no GRDB file" and "no keychain access; device
// not yet unlocked for first time" cases _before_ calling
// setupIfNecessary().
if let errorContent = NSEEnvironment.verifyDBKeysAvailable() {
if hasShownFirstUnlockError.tryToSetFlag() {
NSLog("DB Keys not accessible; showing error.")
contentHandler(errorContent)
} else {
// Only show a single error if we receive multiple pushes
// before first device unlock.
NSLog("DB Keys not accessible; completing silently.")
let emptyContent = UNMutableNotificationContent()
contentHandler(emptyContent)
}
return
}
if let errorContent = environment.setupIfNecessary() {
// This should not occur; see above. If we've reached this
// point, the NSEEnvironment.isSetup flag is already set,
// but the environment has _not_ been setup successfully.
// We need to terminate the NSE to return to a good state.
Logger.warn("Posting error notification and skipping processing.")
Logger.flush()
contentHandler(errorContent)
fatalError("Posting error notification and skipping processing.")
}
self.contentHandler.set(contentHandler)
owsAssertDebug(FeatureFlags.notificationServiceExtension)
let nseCount = Self.nseDidStart()
Logger.info("Received notification in class: \(self), thread: \(Thread.current), pid: \(ProcessInfo.processInfo.processIdentifier), memoryUsage: \(LocalDevice.memoryUsage), nseCount: \(nseCount)")
AppReadiness.runNowOrWhenAppDidBecomeReadySync {
environment.askMainAppToHandleReceipt { [weak self] mainAppHandledReceipt in
guard !mainAppHandledReceipt else {
Logger.info("Received notification handled by main application, memoryUsage: \(LocalDevice.memoryUsage).")
self?.completeSilenty()
return
}
Logger.info("Processing received notification, memoryUsage: \(LocalDevice.memoryUsage).")
self?.fetchAndProcessMessages()
}
}
}
// Called just before the extension will be terminated by the system.
override func serviceExtensionTimeWillExpire() {
owsFailDebug("NSE expired before messages could be processed")
// We complete silently here so that nothing is presented to the user.
// By default the OS will present whatever the raw content of the original
// notification is to the user otherwise.
completeSilenty(timeHasExpired: true)
}
// This method is thread-safe.
private func fetchAndProcessMessages() {
guard !AppExpiry.shared.isExpired else {
owsFailDebug("Not processing notifications for expired application.")
return completeSilenty()
}
environment.processingMessageCounter.increment()
Logger.info("Beginning message fetch.")
let fetchPromise = messageFetcherJob.run().promise
fetchPromise.timeout(seconds: 20, description: "Message Fetch Timeout.") {
NotificationServiceError.timeout
}.catch(on: .global()) { _ in
// Do nothing, Promise.timeout() will log timeouts.
}
fetchPromise.then(on: .global()) { [weak self] () -> Promise<Void> in
Logger.info("Waiting for processing to complete.")
guard let self = self else { return Promise.value(()) }
let runningAndCompletedPromises = AtomicArray<(String, Promise<Void>)>()
let processingCompletePromise = firstly { () -> Promise<Void> in
let promise = self.messageProcessor.processingCompletePromise()
runningAndCompletedPromises.append(("MessageProcessorCompletion", promise))
return promise
}.then(on: .global()) { () -> Promise<Void> in
// Wait until all async side effects of
// message processing are complete.
let completionPromises: [(String, Promise<Void>)] = [
// Wait until all notifications are posted.
("Pending notification post", NotificationPresenter.pendingNotificationsPromise()),
// Wait until all ACKs are complete.
("Pending messageFetch ack", Self.messageFetcherJob.pendingAcksPromise()),
// Wait until all outgoing receipt sends are complete.
("Pending receipt sends", Self.outgoingReceiptManager.pendingSendsPromise()),
// Wait until all outgoing messages are sent.
("Pending outgoing message", Self.messageSender.pendingSendsPromise()),
// Wait until all sync requests are fulfilled.
("Pending sync request", OWSMessageManager.pendingTasksPromise())
]
let joinedPromise = Promise.when(resolved: completionPromises.map { $0.1 })
completionPromises.forEach { runningAndCompletedPromises.append($0) }
return joinedPromise.asVoid()
}
processingCompletePromise.timeout(seconds: 20, description: "Message Processing Timeout.") {
runningAndCompletedPromises.get().filter { $0.1.isSealed == false }.forEach {
Logger.warn("Completion promise: \($0.0) did not finish.")
}
return NotificationServiceError.timeout
}.catch { _ in
// Do nothing, Promise.timeout() will log timeouts.
}
return processingCompletePromise
}.ensure(on: .global()) { [weak self] in
Logger.info("Message fetch completed.")
environment.processingMessageCounter.decrementOrZero()
self?.completeSilenty()
}.catch(on: .global()) { error in
Logger.warn("Error: \(error)")
}
}
private enum NotificationServiceError: Error {
case timeout
}
}