feat: Renaming and moves some items around, listeners now manage reconnection events.

Package.swift

@@ -15,10 +15,9 @@ let package = Package(
   products: [
     .executable(name: "dewpoint-controller", targets: ["DewPointController"]),
     .library(name: "Models", targets: ["Models"]),
-    .library(name: "MQTTConnectionManager", targets: ["MQTTConnectionManager"]),
+    .library(name: "MQTTManager", targets: ["MQTTManager"]),
     .library(name: "MQTTConnectionService", targets: ["MQTTConnectionService"]),
-    .library(name: "SensorsService", targets: ["SensorsService"]),
-    .library(name: "TopicDependencies", targets: ["TopicDependencies"])
+    .library(name: "SensorsService", targets: ["SensorsService"])
   ],
   dependencies: [
     .package(url: "https://github.com/apple/swift-async-algorithms", from: "1.0.0"),
@@ -34,10 +33,9 @@ let package = Package(
       name: "DewPointController",
       dependencies: [
         "Models",
-        "MQTTConnectionManager",
+        "MQTTManager",
         "MQTTConnectionService",
         "SensorsService",
-        "TopicDependencies",
         .product(name: "MQTTNIO", package: "mqtt-nio"),
         .product(name: "NIO", package: "swift-nio"),
         .product(name: "PsychrometricClientLive", package: "swift-psychrometrics")
@@ -52,7 +50,7 @@ let package = Package(
       swiftSettings: swiftSettings
     ),
     .target(
-      name: "MQTTConnectionManager",
+      name: "MQTTManager",
       dependencies: [
         .product(name: "AsyncAlgorithms", package: "swift-async-algorithms"),
         .product(name: "Dependencies", package: "swift-dependencies"),
@@ -65,7 +63,7 @@ let package = Package(
       name: "MQTTConnectionService",
       dependencies: [
         "Models",
-        "MQTTConnectionManager",
+        "MQTTManager",
         .product(name: "ServiceLifecycle", package: "swift-service-lifecycle")
       ],
       swiftSettings: swiftSettings
@@ -74,7 +72,7 @@ let package = Package(
       name: "MQTTConnectionServiceTests",
       dependencies: [
         "MQTTConnectionService",
-        "MQTTConnectionManager",
+        "MQTTManager",
         .product(name: "ServiceLifecycleTestKit", package: "swift-service-lifecycle")
       ]
     ),
@@ -82,8 +80,7 @@ let package = Package(
       name: "SensorsService",
       dependencies: [
         "Models",
-        "MQTTConnectionManager",
-        "TopicDependencies",
+        "MQTTManager",
         .product(name: "Dependencies", package: "swift-dependencies"),
         .product(name: "DependenciesMacros", package: "swift-dependencies"),
         .product(name: "MQTTNIO", package: "mqtt-nio"),
@@ -97,15 +94,6 @@ let package = Package(
         "SensorsService",
         .product(name: "PsychrometricClientLive", package: "swift-psychrometrics")
       ]
-    ),
-    .target(
-      name: "TopicDependencies",
-      dependencies: [
-        .product(name: "Dependencies", package: "swift-dependencies"),
-        .product(name: "DependenciesMacros", package: "swift-dependencies"),
-        .product(name: "MQTTNIO", package: "mqtt-nio")
-      ],
-      swiftSettings: swiftSettings
     )
   ]
 )

Sources/DewPointController/Application.swift

@@ -2,14 +2,13 @@ import Dependencies
 import Foundation
 import Logging
 import Models
-import MQTTConnectionManager
 import MQTTConnectionService
+import MQTTManager
 import MQTTNIO
 import NIO
 import PsychrometricClientLive
 import SensorsService
 import ServiceLifecycle
-import TopicDependencies
 
 @main
 struct Application {
@@ -38,9 +37,7 @@ struct Application {
     do {
       try await withDependencies {
         $0.psychrometricClient = .liveValue
-        $0.topicListener = .live(client: mqtt)
-        $0.topicPublisher = .live(client: mqtt)
-        $0.mqttConnectionManager = .live(client: mqtt, logger: logger)
+        $0.mqtt = .live(client: mqtt, logger: logger)
       } operation: {
         let mqttConnection = MQTTConnectionService(logger: logger)
         let sensors = SensorsService(sensors: .live, logger: logger)

Sources/MQTTConnectionManager/Live.swift

@@ -1,221 +0,0 @@
-import AsyncAlgorithms
-import Dependencies
-import DependenciesMacros
-import Foundation
-import Logging
-import MQTTNIO
-import NIO
-
-public extension DependencyValues {
-
-  /// A dependency that is responsible for managing the connection to
-  /// an MQTT broker.
-  var mqttConnectionManager: MQTTConnectionManager {
-    get { self[MQTTConnectionManager.self] }
-    set { self[MQTTConnectionManager.self] = newValue }
-  }
-}
-
-/// Represents the interface needed for the ``MQTTConnectionService``.
-///
-/// See ``MQTTConnectionManagerLive`` module for live implementation.
-@DependencyClient
-public struct MQTTConnectionManager: Sendable {
-
-  /// Connect to the MQTT broker.
-  public var connect: @Sendable () async throws -> Void
-
-  /// Shutdown the connection to the MQTT broker.
-  ///
-  /// - Note: You should cancel any tasks that are listening to the connection stream first.
-  public var shutdown: @Sendable () -> Void
-
-  /// Create a stream of connection events.
-  public var stream: @Sendable () throws -> AsyncStream<Event>
-
-  /// Perform an operation with the underlying MQTTClient, this can be useful in
-  /// tests, so this module needs imported with `@_spi(Testing) import` to use this method.
-  private var _withClient: @Sendable ((MQTTClient) async throws -> Void) async throws -> Void
-
-  @_spi(Internal)
-  public func withClient(
-    _ callback: @Sendable (MQTTClient) async throws -> Void
-  ) async throws {
-    try await _withClient(callback)
-  }
-
-  /// Represents connection events that clients can listen for and
-  /// react accordingly.
-  public enum Event: Sendable {
-    case connected
-    case disconnected
-    case shuttingDown
-  }
-
-  public static func live(
-    client: MQTTClient,
-    cleanSession: Bool = false,
-    logger: Logger? = nil,
-    alwaysReconnect: Bool = true
-  ) -> Self {
-    let manager = ConnectionManager(
-      client: client,
-      logger: logger,
-      alwaysReconnect: alwaysReconnect
-    )
-    return .init {
-      try await manager.connect(cleanSession: cleanSession)
-    } shutdown: {
-      manager.shutdown()
-    } stream: {
-      MQTTConnectionStream(client: client, logger: logger)
-        .start()
-        .removeDuplicates()
-        .eraseToStream()
-    } _withClient: { callback in
-      try await callback(client)
-    }
-  }
-}
-
-extension MQTTConnectionManager: TestDependencyKey {
-  public static var testValue: MQTTConnectionManager {
-    Self()
-  }
-}
-
-// MARK: - Helpers
-
-@_spi(Internal)
-public final actor MQTTConnectionStream: Sendable {
-
-  public typealias Element = MQTTConnectionManager.Event
-
-  private let client: MQTTClient
-  private let continuation: AsyncStream<Element>.Continuation
-  private let logger: Logger?
-  private let name: String
-  private let stream: AsyncStream<Element>
-  private var isShuttingDown = false
-
-  public init(client: MQTTClient, logger: Logger?) {
-    let (stream, continuation) = AsyncStream<Element>.makeStream()
-    self.client = client
-    self.continuation = continuation
-    self.logger = logger
-    self.name = UUID().uuidString
-    self.stream = stream
-  }
-
-  deinit { stop() }
-
-  public nonisolated func start() -> AsyncStream<Element> {
-    // Check if the client is active and yield the initial result.
-    continuation.yield(client.isActive() ? .connected : .disconnected)
-
-    // Continually check if the client is active.
-    let task = Task {
-      let isShuttingDown = await self.isShuttingDown
-      while !Task.isCancelled, !isShuttingDown {
-        try await Task.sleep(for: .milliseconds(100))
-        continuation.yield(client.isActive() ? .connected : .disconnected)
-      }
-    }
-
-    // Register listener on the client for when the connection
-    // closes.
-    client.addCloseListener(named: name) { _ in
-      self.logger?.trace("Client has disconnected.")
-      self.continuation.yield(.disconnected)
-    }
-
-    // Register listener on the client for when the client
-    // is shutdown.
-    client.addShutdownListener(named: name) { _ in
-      self.logger?.trace("Client is shutting down, ending connection stream: \(self.name)")
-      self.continuation.yield(.shuttingDown)
-      Task { await self.setIsShuttingDown() }
-      task.cancel()
-      self.stop()
-    }
-
-    return stream
-  }
-
-  private func setIsShuttingDown() {
-    isShuttingDown = true
-  }
-
-  public nonisolated func stop() {
-    client.removeCloseListener(named: name)
-    client.removeShutdownListener(named: name)
-    continuation.finish()
-  }
-
-}
-
-actor ConnectionManager {
-  private let client: MQTTClient
-  private let logger: Logger?
-  private let name: String
-  private let shouldReconnect: Bool
-  private var hasConnected: Bool = false
-
-  init(
-    client: MQTTClient,
-    logger: Logger?,
-    alwaysReconnect: Bool
-  ) {
-    self.client = client
-    self.logger = logger
-    self.name = UUID().uuidString
-    self.shouldReconnect = alwaysReconnect
-  }
-
-  deinit {
-    // We should've already logged that we're shutting down if
-    // the manager was shutdown properly, so don't log it twice.
-    self.shutdown(withLogging: false)
-  }
-
-  private func setHasConnected() {
-    hasConnected = true
-  }
-
-  func connect(
-    cleanSession: Bool
-  ) async throws {
-    guard !hasConnected else { return }
-    do {
-      try await client.connect(cleanSession: cleanSession)
-      setHasConnected()
-
-      client.addCloseListener(named: name) { [weak self] _ in
-        guard let `self` else { return }
-        self.logger?.debug("Connection closed.")
-        if self.shouldReconnect {
-          self.logger?.debug("Reconnecting...")
-          Task {
-            try await self.connect(cleanSession: cleanSession)
-          }
-        }
-      }
-
-      client.addShutdownListener(named: name) { _ in
-        self.shutdown()
-      }
-
-    } catch {
-      logger?.trace("Failed to connect: \(error)")
-      throw error
-    }
-  }
-
-  nonisolated func shutdown(withLogging: Bool = true) {
-    if withLogging {
-      logger?.trace("Shutting down connection.")
-    }
-    client.removeCloseListener(named: name)
-    client.removeShutdownListener(named: name)
-  }
-}

Sources/MQTTConnectionService/MQTTConnectionService.swift

@@ -1,13 +1,13 @@
 import Dependencies
 import Logging
 import Models
-import MQTTConnectionManager
+import MQTTManager
 import ServiceLifecycle
 
-public actor MQTTConnectionService: Service {
-  @Dependency(\.mqttConnectionManager) var manager
+public struct MQTTConnectionService: Service {
+  @Dependency(\.mqtt) var mqtt
 
-  private nonisolated let logger: Logger?
+  private let logger: Logger?
 
   public init(
     logger: Logger? = nil
@@ -20,8 +20,8 @@ public actor MQTTConnectionService: Service {
   /// connection.
   public func run() async throws {
     try await withGracefulShutdownHandler {
-      try await manager.connect()
-      for await event in try manager.stream().cancelOnGracefulShutdown() {
+      try await mqtt.connect()
+      for await event in try mqtt.connectionStream().cancelOnGracefulShutdown() {
         // We don't really need to do anything with the events, so just logging
         // for now.  But we need to iterate on an async stream for the service to
         // continue to run and handle graceful shutdowns.
@@ -29,7 +29,7 @@ public actor MQTTConnectionService: Service {
       }
       // when we reach here we are shutting down, so we shutdown
       // the manager.
-      manager.shutdown()
+      mqtt.shutdown()
     } onGracefulShutdown: {
       self.logger?.trace("Received graceful shutdown.")
     }

Sources/MQTTManager/Interface.swift

@@ -0,0 +1,197 @@
+import AsyncAlgorithms
+import Dependencies
+import DependenciesMacros
+import Foundation
+import Logging
+import MQTTNIO
+import NIO
+
+public extension DependencyValues {
+
+  /// A dependency that is responsible for managing the connection to
+  /// an MQTT broker.
+  var mqtt: MQTTManager {
+    get { self[MQTTManager.self] }
+    set { self[MQTTManager.self] = newValue }
+  }
+}
+
+/// Represents the interface needed for the ``MQTTConnectionService``.
+///
+/// See ``MQTTConnectionManagerLive`` module for live implementation.
+@DependencyClient
+public struct MQTTManager: Sendable {
+
+  public typealias ListenStream = AsyncStream<MQTTPublishInfo>
+
+  /// Connect to the MQTT broker.
+  public var connect: @Sendable () async throws -> Void
+
+  /// Create a stream of connection events.
+  public var connectionStream: @Sendable () throws -> AsyncStream<Event>
+
+  private var _listen: @Sendable ([String], MQTTQoS) async throws -> ListenStream
+
+  /// Publish a value to the MQTT broker for a given topic.
+  public var publish: @Sendable (PublishRequest) async throws -> Void
+
+  /// Shutdown the connection to the MQTT broker.
+  public var shutdown: @Sendable () -> Void
+
+  /// Perform an operation with the underlying MQTTClient, this can be useful in
+  /// tests, so this module needs imported with `@_spi(Testing) import` to use this method.
+  private var _withClient: @Sendable ((MQTTClient) async throws -> Void) async throws -> Void
+
+  /// Create an async stream that listens for changes to the given topics.
+  ///
+  /// - Parameters:
+  ///   - topics: The topics to listen for changes to.
+  ///   - qos: The MQTTQoS for the subscription.
+  public func listen(
+    to topics: [String],
+    qos: MQTTQoS = .atLeastOnce
+  ) async throws -> ListenStream {
+    try await _listen(topics, qos)
+  }
+
+  /// Create an async stream that listens for changes to the given topics.
+  ///
+  /// - Parameters:
+  ///   - topics: The topics to listen for changes to.
+  ///   - qos: The MQTTQoS for the subscription.
+  public func listen(
+    _ topics: String...,
+    qos: MQTTQoS = .atLeastOnce
+  ) async throws -> ListenStream {
+    try await listen(to: topics, qos: qos)
+  }
+
+  /// Publish a new value to the given topic.
+  ///
+  /// - Parameters:
+  ///   - payload: The value to publish.
+  ///   - topicName: The topic to publish the new value to.
+  ///   - qos: The MQTTQoS.
+  ///   - retain: The retain flag.
+  public func publish(
+    _ payload: ByteBuffer,
+    to topicName: String,
+    qos: MQTTQoS,
+    retain: Bool = false
+  ) async throws {
+    try await publish(.init(
+      topicName: topicName,
+      payload: payload,
+      qos: qos,
+      retain: retain
+    ))
+  }
+
+  /// Perform an operation with the underlying MQTTClient, this can be useful in
+  /// tests, so this module needs imported with `@_spi(Testing) import` to use this method.
+  @_spi(Internal)
+  public func withClient(
+    _ callback: @Sendable (MQTTClient) async throws -> Void
+  ) async throws {
+    try await _withClient(callback)
+  }
+
+  /// Represents connection events that clients can listen for and
+  /// react accordingly.
+  public enum Event: Sendable {
+    case connected
+    case disconnected
+    case shuttingDown
+  }
+
+  /// Represents the parameters required to publish a new value to the
+  /// MQTT broker.
+  public struct PublishRequest: Equatable, Sendable {
+
+    /// The topic to publish the new value to.
+    public let topicName: String
+
+    /// The value to publish.
+    public let payload: ByteBuffer
+
+    /// The qos of the request.
+    public let qos: MQTTQoS
+
+    /// The retain flag for the request.
+    public let retain: Bool
+
+    /// Create a new publish request.
+    ///
+    /// - Parameters:
+    ///   - topicName: The topic to publish to.
+    ///   - payload: The value to publish.
+    ///   - qos: The qos of the request.
+    ///   - retain: The retain flag of the request.
+    public init(
+      topicName: String,
+      payload: ByteBuffer,
+      qos: MQTTQoS,
+      retain: Bool
+    ) {
+      self.topicName = topicName
+      self.payload = payload
+      self.qos = qos
+      self.retain = retain
+    }
+  }
+
+}
+
+public extension MQTTManager {
+  /// Create the live manager.
+  ///
+  static func live(
+    client: MQTTClient,
+    cleanSession: Bool = false,
+    logger: Logger? = nil,
+    alwaysReconnect: Bool = true
+  ) -> Self {
+    let manager = ConnectionManager(
+      client: client,
+      logger: logger,
+      alwaysReconnect: alwaysReconnect
+    )
+    return .init(
+      connect: { try await manager.connect(cleanSession: cleanSession) },
+      connectionStream: {
+        MQTTConnectionStream(client: client, logger: logger)
+          .start()
+          .removeDuplicates()
+          .eraseToStream()
+      },
+      _listen: { topics, qos in
+        try await manager.listen(to: topics, qos: qos)
+      },
+      publish: { request in
+        let topic = request.topicName
+        guard client.isActive() else {
+          logger?.debug("Client is not active, unable to publish to topic: \(topic)")
+          return
+        }
+        logger?.trace("Begin publishing to topic: \(topic)")
+        defer { logger?.trace("Done publishing to topic: \(topic)") }
+        try await client.publish(
+          to: request.topicName,
+          payload: request.payload,
+          qos: request.qos,
+          retain: request.retain
+        )
+      },
+      shutdown: {
+        manager.shutdown()
+      },
+      _withClient: { callback in
+        try await callback(client)
+      }
+    )
+  }
+}
+
+extension MQTTManager: TestDependencyKey {
+  public static let testValue: MQTTManager = Self()
+}

Sources/MQTTManager/Internal/ConnectionManager.swift

@@ -0,0 +1,98 @@
+import Foundation
+import Logging
+import MQTTNIO
+
+actor ConnectionManager {
+  private let client: MQTTClient
+  private let logger: Logger?
+  private let name: String
+  private let shouldReconnect: Bool
+  private var hasConnected: Bool = false
+  private var listeners: [TopicListenerStream] = []
+  private var isShuttingDown = false
+
+  init(
+    client: MQTTClient,
+    logger: Logger?,
+    alwaysReconnect: Bool
+  ) {
+    var logger = logger
+    logger?[metadataKey: "instance"] = "\(Self.self)"
+    self.logger = logger
+
+    self.client = client
+    self.name = UUID().uuidString
+    self.shouldReconnect = alwaysReconnect
+  }
+
+  deinit {
+    if !isShuttingDown {
+      let message = """
+      Did not properly close the connection manager. This can lead to
+      dangling references.
+
+      Please call `shutdown` to properly close all connections and listener streams.
+      """
+      logger?.warning("\(message)")
+      self.shutdown()
+    }
+  }
+
+  private func setHasConnected() {
+    hasConnected = true
+  }
+
+  func listen(
+    to topics: [String],
+    qos: MQTTQoS
+  ) async throws -> MQTTManager.ListenStream {
+    let listener = TopicListenerStream(client: client, logger: logger, topics: topics, qos: qos)
+    listeners.append(listener)
+    await listener.start()
+    return listener.stream
+  }
+
+  func connect(
+    cleanSession: Bool
+  ) async throws {
+    guard !hasConnected else { return }
+    do {
+      try await client.connect(cleanSession: cleanSession)
+      setHasConnected()
+
+      client.addCloseListener(named: name) { [weak self] _ in
+        guard let `self` else { return }
+        self.logger?.debug("Connection closed.")
+        if self.shouldReconnect {
+          self.logger?.debug("Reconnecting...")
+          Task {
+            try await self.connect(cleanSession: cleanSession)
+          }
+        }
+      }
+
+      client.addShutdownListener(named: name) { _ in
+        self.shutdown()
+      }
+
+    } catch {
+      logger?.trace("Failed to connect: \(error)")
+      throw error
+    }
+  }
+
+  private func shutdownListeners() {
+    _ = listeners.map { $0.shutdown() }
+    listeners = []
+    isShuttingDown = true
+  }
+
+  nonisolated func shutdown(withLogging: Bool = true) {
+    if withLogging {
+      logger?.trace("Shutting down connection.")
+    }
+    client.removeCloseListener(named: name)
+    client.removeShutdownListener(named: name)
+    Task { await shutdownListeners() }
+  }
+}

Sources/MQTTManager/Internal/ConnectionStream.swift

@@ -0,0 +1,74 @@
+import Foundation
+import Logging
+import MQTTNIO
+
+@_spi(Internal)
+public actor MQTTConnectionStream: Sendable {
+
+  public typealias Element = MQTTManager.Event
+
+  private let client: MQTTClient
+  private let continuation: AsyncStream<Element>.Continuation
+  private let logger: Logger?
+  nonisolated let name: String
+  private let stream: AsyncStream<Element>
+  private var isShuttingDown = false
+
+  public init(client: MQTTClient, logger: Logger?) {
+    var logger = logger
+    logger?[metadataKey: "type"] = "\(Self.self)"
+    self.logger = logger
+
+    let (stream, continuation) = AsyncStream<Element>.makeStream()
+    self.client = client
+    self.continuation = continuation
+    self.name = UUID().uuidString
+    self.stream = stream
+  }
+
+  deinit { stop() }
+
+  public nonisolated func start() -> AsyncStream<Element> {
+    // Check if the client is active and yield the initial result.
+    continuation.yield(client.isActive() ? .connected : .disconnected)
+
+    // Continually check if the client is active.
+    let task = Task {
+      let isShuttingDown = await self.isShuttingDown
+      while !Task.isCancelled, !isShuttingDown {
+        try await Task.sleep(for: .milliseconds(100))
+        continuation.yield(client.isActive() ? .connected : .disconnected)
+      }
+    }
+
+    // Register listener on the client for when the connection
+    // closes.
+    client.addCloseListener(named: name) { _ in
+      self.logger?.trace("Client has disconnected.")
+      self.continuation.yield(.disconnected)
+    }
+
+    // Register listener on the client for when the client
+    // is shutdown.
+    client.addShutdownListener(named: name) { _ in
+      self.logger?.trace("Client is shutting down, ending connection stream: \(self.name)")
+      self.continuation.yield(.shuttingDown)
+      Task { await self.setIsShuttingDown() }
+      task.cancel()
+      self.stop()
+    }
+
+    return stream
+  }
+
+  private func setIsShuttingDown() {
+    isShuttingDown = true
+  }
+
+  public nonisolated func stop() {
+    client.removeCloseListener(named: name)
+    client.removeShutdownListener(named: name)
+    continuation.finish()
+  }
+
+}

Sources/MQTTManager/Internal/TopicListenerStream.swift

@@ -0,0 +1,177 @@
+import Foundation
+import Logging
+import MQTTNIO
+
+actor TopicListenerStream {
+
+  typealias Stream = MQTTManager.ListenStream
+
+  private let client: MQTTClient
+  private let configuration: Configuration
+  private let continuation: Stream.Continuation
+  private let logger: Logger?
+  private let name: String
+  let stream: Stream
+  private var shuttingDown: Bool = false
+  private var onShutdownHandler: (@Sendable () -> Void)?
+
+  init(
+    client: MQTTClient,
+    logger: Logger?,
+    topics: [String],
+    qos: MQTTQoS
+  ) {
+    // Setup the logger so we can more easily decipher log messages.
+    var logger = logger
+    logger?[metadataKey: "type"] = "\(Self.self)"
+    self.logger = logger
+
+    let (stream, continuation) = Stream.makeStream()
+    self.client = client
+    self.configuration = .init(qos: qos, topics: topics)
+    self.continuation = continuation
+    self.name = UUID().uuidString
+    self.stream = stream
+  }
+
+  struct Configuration: Sendable {
+    let qos: MQTTQoS
+    let topics: [String]
+  }
+
+  deinit {
+    if !shuttingDown {
+      let message = """
+      Shutdown was not called on topic listener. This could lead to potential errors or
+      the stream never ending.
+
+      Please ensure that you call shutdown on the listener.
+      """
+      client.logger.warning("\(message)")
+      continuation.finish()
+    }
+    client.removePublishListener(named: name)
+    client.removeShutdownListener(named: name)
+  }
+
+  private func subscribe() async throws {
+    guard !shuttingDown else { return }
+    logger?.debug("Begin subscribing to topics.")
+    do {
+      _ = try await client.subscribe(to: configuration.topics.map {
+        MQTTSubscribeInfo(topicFilter: $0, qos: configuration.qos)
+      })
+    } catch {
+      logger?.error("Received error while subscribing to topics: \(configuration.topics)")
+      throw TopicListenerError.failedToSubscribe
+    }
+    logger?.debug("Done subscribing to topics.")
+  }
+
+  public func start() {
+    logger?.trace("Starting listener for topics: \(configuration.topics)")
+
+    let stream = MQTTConnectionStream(client: client, logger: logger)
+      .start()
+      .removeDuplicates()
+      .eraseToStream()
+
+    let task = Task {
+      // Listen for connection events to restablish the stream upon a
+      // client becoming disconnected / reconnected, and properly shutdown
+      // the stream on the client being shutdown.
+      for await event in stream {
+        logger?.trace("Received event: \(event)")
+        switch event {
+        case .shuttingDown:
+          shutdown()
+        case .disconnected:
+          try await Task.sleep(for: .milliseconds(100))
+        case .connected:
+          try await subscribe()
+          client.addPublishListener(named: name) { result in
+            switch result {
+            case let .failure(error):
+              self.logger?.error("Received error while listening: \(error)")
+            case let .success(publishInfo):
+              if self.configuration.topics.contains(publishInfo.topicName) {
+                self.logger?.debug("Recieved new value for topic: \(publishInfo.topicName)")
+                self.continuation.yield(publishInfo)
+              }
+            }
+          }
+        }
+      }
+    }
+
+    onShutdownHandler = { task.cancel() }
+  }
+
+  // TODO: remove.
+  func listen(
+    _ topics: [String],
+    _ qos: MQTTQoS = .atLeastOnce
+  ) async throws -> Stream {
+    var sleepTimes = 0
+
+    while !client.isActive() {
+      guard sleepTimes < 10 else {
+        throw TopicListenerError.connectionTimeout
+      }
+      try? await Task.sleep(for: .milliseconds(100))
+      sleepTimes += 1
+    }
+
+    client.logger.trace("Client is active, begin subscribing to topics.")
+
+    try await subscribe()
+
+    client.logger.trace("Done subscribing, begin listening to topics.")
+
+    client.addPublishListener(named: name) { result in
+      switch result {
+      case let .failure(error):
+        self.logger?.error("Received error while listening: \(error)")
+      case let .success(publishInfo):
+        if topics.contains(publishInfo.topicName) {
+          self.logger?.debug("Recieved new value for topic: \(publishInfo.topicName)")
+          self.continuation.yield(publishInfo)
+        }
+      }
+    }
+
+    return stream
+  }
+
+  private func setIsShuttingDown() {
+    shuttingDown = true
+    onShutdownHandler = nil
+  }
+
+  public nonisolated func shutdown() {
+    client.logger.trace("Closing topic listener...")
+    continuation.finish()
+    client.removePublishListener(named: name)
+    client.removeShutdownListener(named: name)
+    Task {
+      await onShutdownHandler?()
+      await self.setIsShuttingDown()
+    }
+  }
+
+}
+
+// MARK: - Errors
+
+public enum TopicListenerError: Error {
+  case connectionTimeout
+  case failedToSubscribe
+}
+
+public struct MQTTListenResultError: Error {
+  let underlyingError: any Error
+
+  init(_ underlyingError: any Error) {
+    self.underlyingError = underlyingError
+  }
+}

Sources/SensorsService/Helpers.swift

@@ -1,42 +0,0 @@
-import NIO
-import NIOFoundationCompat
-import PsychrometricClient
-
-/// Represents a type that can be initialized by a ``ByteBuffer``.
-protocol BufferInitalizable {
-  init?(buffer: inout ByteBuffer)
-}
-
-extension Double: BufferInitalizable {
-
-  /// Attempt to create / parse a double from a byte buffer.
-  init?(buffer: inout ByteBuffer) {
-    guard let string = buffer.readString(
-      length: buffer.readableBytes,
-      encoding: String.Encoding.utf8
-    )
-    else { return nil }
-    self.init(string)
-  }
-}
-
-extension Tagged: BufferInitalizable where RawValue: BufferInitalizable {
-  init?(buffer: inout ByteBuffer) {
-    guard let value = RawValue(buffer: &buffer) else { return nil }
-    self.init(value)
-  }
-}
-
-extension Humidity<Relative>: BufferInitalizable {
-  init?(buffer: inout ByteBuffer) {
-    guard let value = Double(buffer: &buffer) else { return nil }
-    self.init(value)
-  }
-}
-
-extension Temperature<DryAir>: BufferInitalizable {
-  init?(buffer: inout ByteBuffer) {
-    guard let value = Double(buffer: &buffer) else { return nil }
-    self.init(value)
-  }
-}

Sources/SensorsService/SensorsService.swift

@@ -3,12 +3,11 @@ import DependenciesMacros
 import Foundation
 import Logging
 import Models
-import MQTTConnectionManager
+import MQTTManager
 import MQTTNIO
 import NIO
 import PsychrometricClient
 import ServiceLifecycle
-import TopicDependencies
 
 /// Service that is responsible for listening to changes of the temperature and humidity
 /// sensors, then publishing back the calculated dew-point temperature and enthalpy for
@@ -17,9 +16,7 @@ import TopicDependencies
 ///
 public actor SensorsService: Service {
 
-  @Dependency(\.mqttConnectionManager.stream) var connectionStream
-  @Dependency(\.topicListener) var topicListener
-  @Dependency(\.topicPublisher) var topicPublisher
+  @Dependency(\.mqtt) var mqtt
 
   /// The logger to use for the service.
   private let logger: Logger?
@@ -27,12 +24,9 @@ public actor SensorsService: Service {
   /// The sensors that we are listening for updates to, so
   /// that we can calculate the dew-point temperature and enthalpy
   /// values to publish back to the MQTT broker.
-  var sensors: [TemperatureAndHumiditySensor]
+  private var sensors: [TemperatureAndHumiditySensor]
 
-  @_spi(Internal)
-  public var isListening: Bool = false
-
-  var topics: [String] {
+  private var topics: [String] {
     sensors.reduce(into: [String]()) { array, sensor in
       array.append(sensor.topics.temperature)
       array.append(sensor.topics.humidity)
@@ -60,33 +54,16 @@ public actor SensorsService: Service {
   public func run() async throws {
     precondition(sensors.count > 0, "Sensors should not be empty.")
 
-    try await withGracefulShutdownHandler {
-      // Listen for connection events, so that we can automatically
-      // reconnect any sensor topics we're listening to upon a disconnect / reconnect
-      // event.  We can also shutdown any topic listeners upon a shutdown event.
-      for await event in try connectionStream().cancelOnGracefulShutdown() {
-        switch event {
-        case .shuttingDown:
-          logger?.debug("Received shutdown event.")
-          isListening = false
-          try await self.shutdown()
-        case .disconnected:
-          logger?.debug("Received disconnected event.")
-          isListening = false
-          try await Task.sleep(for: .milliseconds(100))
-        case .connected:
-          logger?.debug("Received connected event.")
-          let stream = try await makeStream()
-          isListening = true
-          for await result in stream.cancelOnGracefulShutdown() {
-            logger?.debug("Received result for topic: \(result.topic)")
-            await self.handleResult(result)
-          }
-        }
+    let stream = try await makeStream()
+
+    await withGracefulShutdownHandler {
+      for await result in stream.cancelOnGracefulShutdown() {
+        logger?.debug("Received result for topic: \(result.topic)")
+        await handleResult(result)
       }
     } onGracefulShutdown: {
+      self.logger?.debug("Received graceful shutdown.")
       Task {
-        self.logger?.debug("Received graceful shutdown.")
         try await self.shutdown()
       }
     }
@@ -95,24 +72,13 @@ public actor SensorsService: Service {
   @_spi(Internal)
   public func shutdown() async throws {
     try await publishUpdates()
-    topicListener.shutdown()
   }
 
   private func makeStream() async throws -> AsyncStream<(buffer: ByteBuffer, topic: String)> {
-    try await topicListener.listen(to: topics)
-      // ignore errors, so that we continue to listen, but log them
-      // for debugging purposes.
-      .compactMap { result in
-        switch result {
-        case let .failure(error):
-          self.logger?.debug("Received error listening for sensors: \(error)")
-          return nil
-        case let .success(info):
-          return (info.payload, info.topicName)
-        }
-      }
-      // ignore duplicate values, to prevent publishing dew-point and enthalpy
-      // changes to frequently.
+    // ignore duplicate values, to prevent publishing dew-point and enthalpy
+    // changes to frequently.
+    try await mqtt.listen(to: topics)
+      .map { ($0.payload, $0.topicName) }
       .removeDuplicates { lhs, rhs in
         lhs.buffer == rhs.buffer
           && lhs.topic == rhs.topic
@@ -127,8 +93,7 @@ public actor SensorsService: Service {
       logger?.debug("Begin handling result for topic: \(topic)")
 
       func decode<V: BufferInitalizable>(_: V.Type) -> V? {
-        var buffer = result.buffer
-        return V(buffer: &buffer)
+        return V(buffer: result.buffer)
       }
 
       if topic.contains("temperature") {
@@ -159,9 +124,9 @@ public actor SensorsService: Service {
 
   private func publish(_ double: Double?, to topic: String) async throws {
     guard let double else { return }
-    try await topicPublisher.publish(
+    try await mqtt.publish(
+      ByteBufferAllocator().buffer(string: "\(double)"),
       to: topic,
-      payload: ByteBufferAllocator().buffer(string: "\(double)"),
       qos: .exactlyOnce,
       retain: true
     )
@@ -210,3 +175,38 @@ private extension Array where Element == TemperatureAndHumiditySensor {
     self[index].needsProcessed = false
   }
 }
+
+/// Represents a type that can be initialized by a ``ByteBuffer``.
+protocol BufferInitalizable {
+  init?(buffer: ByteBuffer)
+}
+
+extension Double: BufferInitalizable {
+
+  /// Attempt to create / parse a double from a byte buffer.
+  init?(buffer: ByteBuffer) {
+    let string = String(buffer: buffer)
+    self.init(string)
+  }
+}
+
+extension Tagged: BufferInitalizable where RawValue: BufferInitalizable {
+  init?(buffer: ByteBuffer) {
+    guard let value = RawValue(buffer: buffer) else { return nil }
+    self.init(value)
+  }
+}
+
+extension Humidity<Relative>: BufferInitalizable {
+  init?(buffer: ByteBuffer) {
+    guard let value = Double(buffer: buffer) else { return nil }
+    self.init(value)
+  }
+}
+
+extension Temperature<DryAir>: BufferInitalizable {
+  init?(buffer: ByteBuffer) {
+    guard let value = Double(buffer: buffer) else { return nil }
+    self.init(value)
+  }
+}

Sources/TopicDependencies/TopicListener.swift

@@ -1,186 +0,0 @@
-import Dependencies
-import DependenciesMacros
-import Foundation
-import MQTTNIO
-
-/// A dependency that can generate an async stream of changes to the given topics.
-///
-/// - Note: This type only conforms to ``TestDependencyKey`` because it requires an MQTTClient
-/// to generate the live dependency.
-@DependencyClient
-public struct TopicListener: Sendable {
-
-  public typealias Stream = AsyncStream<Result<MQTTPublishInfo, any Error>>
-
-  /// Create an async stream that listens for changes to the given topics.
-  private var _listen: @Sendable ([String], MQTTQoS) async throws -> Stream
-
-  /// Shutdown the listener stream.
-  public var shutdown: @Sendable () -> Void
-
-  /// Create a new topic listener.
-  ///
-  /// - Parameters:
-  ///   - listen: Generate an async stream of changes for the given topics.
-  ///   - shutdown: Shutdown the topic listener stream.
-  public init(
-    listen: @Sendable @escaping ([String], MQTTQoS) async throws -> Stream,
-    shutdown: @Sendable @escaping () -> Void
-  ) {
-    self._listen = listen
-    self.shutdown = shutdown
-  }
-
-  /// Create an async stream that listens for changes to the given topics.
-  ///
-  /// - Parameters:
-  ///   - topics: The topics to listen for changes to.
-  ///   - qos: The MQTTQoS for the subscription.
-  public func listen(
-    to topics: [String],
-    qos: MQTTQoS = .atLeastOnce
-  ) async throws -> Stream {
-    try await _listen(topics, qos)
-  }
-
-  /// Create an async stream that listens for changes to the given topics.
-  ///
-  /// - Parameters:
-  ///   - topics: The topics to listen for changes to.
-  ///   - qos: The MQTTQoS for the subscription.
-  public func listen(
-    _ topics: String...,
-    qos: MQTTQoS = .atLeastOnce
-  ) async throws -> Stream {
-    try await listen(to: topics, qos: qos)
-  }
-
-  /// Create the live implementation of the topic listener with the given MQTTClient.
-  ///
-  /// - Parameters:
-  ///   - client: The MQTTClient to use.
-  public static func live(client: MQTTClient) -> Self {
-    let listener = MQTTTopicListener(client: client)
-    return .init(
-      listen: { try await listener.listen($0, $1) },
-      shutdown: { listener.shutdown() }
-    )
-  }
-}
-
-extension TopicListener: TestDependencyKey {
-  public static var testValue: TopicListener { Self() }
-}
-
-public extension DependencyValues {
-  var topicListener: TopicListener {
-    get { self[TopicListener.self] }
-    set { self[TopicListener.self] = newValue }
-  }
-}
-
-// MARK: - Helpers
-
-private actor MQTTTopicListener {
-
-  private let client: MQTTClient
-  private let continuation: TopicListener.Stream.Continuation
-  private let name: String
-  let stream: TopicListener.Stream
-  private var shuttingDown: Bool = false
-
-  init(
-    client: MQTTClient
-  ) {
-    let (stream, continuation) = TopicListener.Stream.makeStream()
-    self.client = client
-    self.continuation = continuation
-    self.name = UUID().uuidString
-    self.stream = stream
-  }
-
-  deinit {
-    if !shuttingDown {
-      let message = """
-      Shutdown was not called on topic listener. This could lead to potential errors or
-      the stream never ending.
-
-      Please ensure that you call shutdown on the listener.
-      """
-      client.logger.warning("\(message)")
-      continuation.finish()
-    }
-    client.removePublishListener(named: name)
-    client.removeShutdownListener(named: name)
-  }
-
-  func listen(
-    _ topics: [String],
-    _ qos: MQTTQoS = .atLeastOnce
-  ) async throws -> TopicListener.Stream {
-    var sleepTimes = 0
-
-    while !client.isActive() {
-      guard sleepTimes < 10 else {
-        throw TopicListenerError.connectionTimeout
-      }
-      try? await Task.sleep(for: .milliseconds(100))
-      sleepTimes += 1
-    }
-
-    client.logger.trace("Client is active, begin subscribing to topics.")
-
-    let subscription = try? await client.subscribe(to: topics.map {
-      MQTTSubscribeInfo(topicFilter: $0, qos: qos)
-    })
-
-    guard subscription != nil else {
-      client.logger.error("Error subscribing to topics: \(topics)")
-      throw TopicListenerError.failedToSubscribe
-    }
-
-    client.logger.trace("Done subscribing, begin listening to topics.")
-
-    client.addPublishListener(named: name) { result in
-      switch result {
-      case let .failure(error):
-        self.client.logger.error("Received error while listening: \(error)")
-        self.continuation.yield(.failure(MQTTListenResultError(error)))
-      case let .success(publishInfo):
-        if topics.contains(publishInfo.topicName) {
-          self.client.logger.trace("Recieved new value for topic: \(publishInfo.topicName)")
-          self.continuation.yield(.success(publishInfo))
-        }
-      }
-    }
-
-    return stream
-  }
-
-  private func setIsShuttingDown() {
-    shuttingDown = true
-  }
-
-  nonisolated func shutdown() {
-    client.logger.trace("Closing topic listener...")
-    continuation.finish()
-    client.removePublishListener(named: name)
-    client.removeShutdownListener(named: name)
-    Task { await self.setIsShuttingDown() }
-  }
-}
-
-// MARK: - Errors
-
-public enum TopicListenerError: Error {
-  case connectionTimeout
-  case failedToSubscribe
-}
-
-public struct MQTTListenResultError: Error {
-  let underlyingError: any Error
-
-  init(_ underlyingError: any Error) {
-    self.underlyingError = underlyingError
-  }
-}

Sources/TopicDependencies/TopicPublisher.swift

@@ -1,117 +0,0 @@
-import Dependencies
-import DependenciesMacros
-import MQTTNIO
-import NIO
-
-/// A dependency that is responsible for publishing values to an MQTT broker.
-///
-/// - Note: This dependency only conforms to `TestDependencyKey` because it
-/// requires an active `MQTTClient` to generate the live dependency.
-@DependencyClient
-public struct TopicPublisher: Sendable {
-
-  private var _publish: @Sendable (PublishRequest) async throws -> Void
-
-  /// Create a new topic publisher.
-  ///
-  /// - Parameters:
-  ///   -  publish: Handle the publish request.
-  public init(
-    publish: @Sendable @escaping (PublishRequest) async throws -> Void
-  ) {
-    self._publish = publish
-  }
-
-  /// Publish a new value to the given topic.
-  ///
-  /// - Parameters:
-  ///   - topicName: The topic to publish the new value to.
-  ///   - payload: The value to publish.
-  ///   - qos: The MQTTQoS.
-  ///   - retain: The retain flag.
-  public func publish(
-    to topicName: String,
-    payload: ByteBuffer,
-    qos: MQTTQoS,
-    retain: Bool = false
-  ) async throws {
-    try await _publish(.init(
-      topicName: topicName,
-      payload: payload,
-      qos: qos,
-      retain: retain
-    ))
-  }
-
-  /// Create the live topic publisher with the given `MQTTClient`.
-  ///
-  /// - Parameters:
-  ///   - client: The mqtt broker client to use.
-  public static func live(client: MQTTClient) -> Self {
-    .init(
-      publish: { request in
-        guard client.isActive() else {
-          client.logger.trace("Client is not connected, unable to publish to \(request.topicName)")
-          return
-        }
-        client.logger.trace("Begin publishing to topic: \(request.topicName)")
-        defer { client.logger.trace("Done publishing to topic: \(request.topicName)") }
-        try await client.publish(
-          to: request.topicName,
-          payload: request.payload,
-          qos: request.qos,
-          retain: request.retain
-        )
-      }
-    )
-  }
-
-  /// Represents the parameters required to publish a new value to the
-  /// MQTT broker.
-  public struct PublishRequest: Equatable, Sendable {
-
-    /// The topic to publish the new value to.
-    public let topicName: String
-
-    /// The value to publish.
-    public let payload: ByteBuffer
-
-    /// The qos of the request.
-    public let qos: MQTTQoS
-
-    /// The retain flag for the request.
-    public let retain: Bool
-
-    /// Create a new publish request.
-    ///
-    /// - Parameters:
-    ///   - topicName: The topic to publish to.
-    ///   - payload: The value to publish.
-    ///   - qos: The qos of the request.
-    ///   - retain: The retain flag of the request.
-    public init(
-      topicName: String,
-      payload: ByteBuffer,
-      qos: MQTTQoS,
-      retain: Bool
-    ) {
-      self.topicName = topicName
-      self.payload = payload
-      self.qos = qos
-      self.retain = retain
-    }
-  }
-}
-
-extension TopicPublisher: TestDependencyKey {
-  public static var testValue: TopicPublisher { Self() }
-}
-
-public extension DependencyValues {
-
-  /// A dependency that is responsible for publishing values to an MQTT broker.
-  var topicPublisher: TopicPublisher {
-    get { self[TopicPublisher.self] }
-    set { self[TopicPublisher.self] = newValue }
-  }
-}

Tests/MQTTConnectionServiceTests/MQTTConnectionServiceTests.swift

@@ -1,8 +1,8 @@
 import AsyncAlgorithms
 import Logging
 import Models
-@_spi(Internal) import MQTTConnectionManager
 import MQTTConnectionService
+@_spi(Internal) import MQTTManager
 import MQTTNIO
 import NIO
 import ServiceLifecycle
@@ -22,15 +22,16 @@ final class MQTTConnectionServiceTests: XCTestCase {
   // TODO: Move to integration tests.
   func testMQTTConnectionStream() async throws {
     let client = createClient(identifier: "testNonManagedStream")
-    let manager = MQTTConnectionManager.live(
+    let manager = MQTTManager.live(
       client: client,
       logger: Self.logger,
       alwaysReconnect: false
     )
+    defer { manager.shutdown() }
     let connectionStream1 = MQTTConnectionStream(client: client, logger: Self.logger)
     let connectionStream2 = MQTTConnectionStream(client: client, logger: Self.logger)
-    var events1 = [MQTTConnectionManager.Event]()
-    var events2 = [MQTTConnectionManager.Event]()
+    var events1 = [MQTTManager.Event]()
+    var events2 = [MQTTManager.Event]()
 
     let stream1 = connectionStream1.start()
     let stream2 = connectionStream2.start()

Tests/SensorsServiceTests/SensorsClientTests.swift

@@ -1,12 +1,11 @@
 import Dependencies
 import Logging
 import Models
-@_spi(Internal) import MQTTConnectionManager
+@_spi(Internal) import MQTTManager
 import MQTTNIO
 import NIO
 import PsychrometricClientLive
 @_spi(Internal) import SensorsService
-import TopicDependencies
 import XCTest
 
 final class SensorsClientTests: XCTestCase {
@@ -23,25 +22,24 @@ final class SensorsClientTests: XCTestCase {
     let client = createClient(identifier: "\(Self.self)")
 
     withDependencies {
-      $0.mqttConnectionManager = .live(client: client, logger: Self.logger)
+      $0.mqtt = .live(client: client, logger: Self.logger)
       $0.psychrometricClient = PsychrometricClient.liveValue
-      $0.topicListener = .live(client: client)
-      $0.topicPublisher = .live(client: client)
     } operation: {
       super.invokeTest()
     }
   }
 
   func testListeningResumesAfterDisconnectThenReconnect() async throws {
-    @Dependency(\.mqttConnectionManager) var manager
     struct TimeoutError: Error {}
 
     let sensor = TemperatureAndHumiditySensor(location: .return)
-    var results = [TopicPublisher.PublishRequest]()
+    let results = ResultContainer()
 
     try await withDependencies {
-      $0.topicPublisher = .capturing { results.append($0) }
+      $0.mqtt.publish = results.append
     } operation: {
+      @Dependency(\.mqtt) var manager
+
       let sensorsService = SensorsService(sensors: [sensor], logger: Self.logger)
       let task = Task { try await sensorsService.run() }
       defer { task.cancel() }
@@ -58,9 +56,7 @@ final class SensorsClientTests: XCTestCase {
         }
 
         // Give time to re-subscribe.
-        while !(await sensorsService.isListening) {
-          try await Task.sleep(for: .milliseconds(100))
-        }
+        try await Task.sleep(for: .milliseconds(200))
 
         try await client.publish(
           to: sensor.topics.temperature,
@@ -77,7 +73,7 @@ final class SensorsClientTests: XCTestCase {
       }
 
       var timeoutCount = 0
-      while !(results.count == 2) {
+      while !(await results.count == 2) {
         guard timeoutCount < 20 else {
           throw TimeoutError()
         }
@@ -85,6 +81,8 @@ final class SensorsClientTests: XCTestCase {
         timeoutCount += 1
       }
 
+      let results = await results.results()
+
       XCTAssertEqual(results.count, 2)
       XCTAssert(results.contains(where: { $0.topicName == sensor.topics.dewPoint }))
       XCTAssert(results.contains(where: { $0.topicName == sensor.topics.enthalpy }))
@@ -122,63 +120,23 @@ final class SensorsClientTests: XCTestCase {
 
 // MARK: Helpers for tests.
 
-class PublishInfoContainer {
-  private(set) var info: [MQTTPublishInfo]
-  private var topicFilters: [String]?
-
-  init(topicFilters: [String]? = nil) {
-    self.info = []
-    self.topicFilters = topicFilters
-  }
-
-  func addPublishInfo(_ info: MQTTPublishInfo) async {
-    guard let topicFilters else {
-      self.info.append(info)
-      return
-    }
-    if topicFilters.contains(info.topicName) {
-      self.info.append(info)
-    }
-  }
-}
-
-extension TopicPublisher {
-  static func capturing(
-    _ callback: @escaping (PublishRequest) -> Void
-  ) -> Self {
-    .init { callback($0) }
-  }
-}
-
-// extension SensorsClient {
-//
-//   static func testing(
-//     yielding: [(value: Double, to: String)],
-//     capturePublishedValues: @escaping (Double, String) -> Void,
-//     captureShutdownEvent: @escaping (Bool) -> Void
-//   ) -> Self {
-//     let (stream, continuation) = AsyncStream.makeStream(of: PublishInfo.self)
-//     let logger = Logger(label: "\(Self.self).testing")
-//
-//     return .init(
-//       listen: { topics in
-//         for (value, topic) in yielding where topics.contains(topic) {
-//           continuation.yield(
-//             (buffer: ByteBuffer(string: "\(value)"), topic: topic)
-//           )
-//         }
-//         return stream
-//       },
-//       logger: logger,
-//       publish: { value, topic in
-//         capturePublishedValues(value, topic)
-//       },
-//       shutdown: {
-//         captureShutdownEvent(true)
-//         continuation.finish()
-//       }
-//     )
-//   }
-// }
-
 struct TopicNotFoundError: Error {}
+
+actor ResultContainer: Sendable {
+
+  private var storage = [MQTTManager.PublishRequest]()
+
+  init() {}
+
+  @Sendable func append(_ result: MQTTManager.PublishRequest) async {
+    storage.append(result)
+  }
+
+  var count: Int {
+    get async { storage.count }
+  }
+
+  func results() async -> [MQTTManager.PublishRequest] {
+    storage
+  }
+}