From d44e286b0ab2be870d9b43e6ef95a586230dcb1c Mon Sep 17 00:00:00 2001
From: Varun Santhanam <talkto@vsanthanam.com>
Date: Sun, 31 Mar 2024 09:06:22 -0700
Subject: [PATCH] Throw cancellation errors when async observation is cancelled

---
 .../NetworkMonitor+Concurrency.swift          | 31 ++++++++++++-------
 .../API/NetworkMonitor/NetworkMonitor.swift   |  4 ++-
 2 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/Sources/NetworkReachability/API/NetworkMonitor/NetworkMonitor+Concurrency.swift b/Sources/NetworkReachability/API/NetworkMonitor/NetworkMonitor+Concurrency.swift
index 7b0616b7..fff0897a 100644
--- a/Sources/NetworkReachability/API/NetworkMonitor/NetworkMonitor+Concurrency.swift
+++ b/Sources/NetworkReachability/API/NetworkMonitor/NetworkMonitor+Concurrency.swift
@@ -31,16 +31,20 @@ public extension NetworkMonitor {
     /// Retrieve the latest known network path using [Swift Concurrency](https://docs.swift.org/swift-book/LanguageGuide/Concurrency.html)
     ///
     /// ```swift
-    /// func updateReachability() async {
-    ///     let path = await NetworkMonitor.networkPath
+    /// func updateReachability() async throws {
+    ///     let path = try await NetworkMonitor.networkPath
     ///     // Do something with `path`
     /// }
     /// ```
     static var networkPath: NWPath {
-        get async {
-            await withUnsafeContinuation { continuation in
+        get async throws {
+            try await withUnsafeThrowingContinuation { continuation in
                 NetworkMonitor.networkPath { path in
-                    continuation.resume(returning: path)
+                    if Task.isCancelled {
+                        continuation.resume(throwing: CancellationError())
+                    } else {
+                        continuation.resume(returning: path)
+                    }
                 }
             }
         }
@@ -55,7 +59,7 @@ public extension NetworkMonitor {
     ///     // Do something with `path`
     /// }
     /// ```
-    static var networkPathUpdates: AsyncStream<NWPath> {
+    static var networkPathUpdates: AsyncThrowingStream<NWPath, any Error> {
         stream(.init())
     }
 
@@ -68,7 +72,7 @@ public extension NetworkMonitor {
     ///     // Do something with `path`
     /// }
     /// ```
-    static func networkPathUpdates(requiringInterfaceType interfaceType: NWInterface.InterfaceType) -> AsyncStream<NWPath> {
+    static func networkPathUpdates(requiringInterfaceType interfaceType: NWInterface.InterfaceType) -> AsyncThrowingStream<NWPath, any Error> {
         stream(.init(requiredInterfaceType: interfaceType))
     }
 
@@ -82,16 +86,21 @@ public extension NetworkMonitor {
     /// }
     /// ```
     @available(macOS 11.0, iOS 14.0, watchOS 7.0, tvOS 14.0, *)
-    static func networkPathUpdates(prohibitingInterfaceTypes interfaceTypes: [NWInterface.InterfaceType]) -> AsyncStream<NWPath> {
+    static func networkPathUpdates(prohibitingInterfaceTypes interfaceTypes: [NWInterface.InterfaceType]) -> AsyncThrowingStream<NWPath, any Error> {
         stream(.init(prohibitedInterfaceTypes: interfaceTypes))
     }
 }
 
 @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
-private func stream(_ monitor: NWPathMonitor) -> AsyncStream<NWPath> {
-    .init(bufferingPolicy: .bufferingNewest(1)) { continuation in
+private func stream(_ monitor: NWPathMonitor) -> AsyncThrowingStream<NWPath, any Error> {
+    .init { continuation in
         monitor.pathUpdateHandler = { path in
-            continuation.yield(path)
+            if Task.isCancelled {
+                monitor.cancel()
+                continuation.finish(throwing: CancellationError())
+            } else {
+                continuation.yield(path)
+            }
         }
         monitor.start(queue: .networkMonitorQueue)
     }
diff --git a/Sources/NetworkReachability/API/NetworkMonitor/NetworkMonitor.swift b/Sources/NetworkReachability/API/NetworkMonitor/NetworkMonitor.swift
index c9636667..ebf06351 100644
--- a/Sources/NetworkReachability/API/NetworkMonitor/NetworkMonitor.swift
+++ b/Sources/NetworkReachability/API/NetworkMonitor/NetworkMonitor.swift
@@ -346,7 +346,9 @@ public final class NetworkMonitor {
                 }
             } else if #available(macOS 10.15, iOS 13, watchOS 6, tvOS 13, *) {
                 Task {
-                    completionHandler(path)
+                    await MainActor.run {
+                        completionHandler(path)
+                    }
                 }
             } else {
                 DispatchQueue.main.async {