fix: serialize ping state updates

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## 26.1.8
+- Fixed a crash in `PingService` caused by concurrent mutation of shared ping state from multiple async ping tasks.
+- Moved ping state tracking and reboot suppression windows into an actor so ping success/failure handling is serialized safely.
+
 ## 26.1.7
 - Added remote reboot support for hosts running KeyHelp API 2.14 or newer.
 - Added a dedicated `APIv2_14` client and mapped 2.14+ hosts to it instead of treating them as API 2.13.

Sources/Model/API/PingService.swift

@@ -2,18 +2,15 @@ import Foundation
 import UserNotifications
 
 enum PingService {
-    private static var previousPingStates: [String: Bool] = [:]
+    private static let stateStore = PingStateStore()
-    private static var suppressedUntil: [String: Date] = [:]
 
-    static func suppressChecks(for hostname: String, duration: TimeInterval) {
+    static func suppressChecks(for hostname: String, duration: TimeInterval) async {
-        suppressedUntil[hostname] = Date().addingTimeInterval(duration)
+        await stateStore.suppressChecks(for: hostname, duration: duration)
     }
 
     static func ping(hostname: String, apiKey: String, notificationsEnabled: Bool = true) async -> Bool {
-        if let suppressedUntil = suppressedUntil[hostname], suppressedUntil > Date() {
+        if await stateStore.shouldSkipPing(for: hostname) {
             return false
-        } else {
-            suppressedUntil.removeValue(forKey: hostname)
         }
 
         guard let url = URL(string: "https://\(hostname)/api/v2/ping") else {
@@ -29,38 +26,32 @@ enum PingService {
         do {
             let (data, response) = try await URLSession.shared.data(for: request)
             if let httpResponse = response as? HTTPURLResponse, httpResponse.statusCode != 200 {
-                handlePingFailure(for: hostname, notificationsEnabled: notificationsEnabled)
+                await handlePingFailure(for: hostname, notificationsEnabled: notificationsEnabled)
                 return false
             }
 
             if let result = try? JSONDecoder().decode([String: String].self, from: data), result["response"] == "pong" {
-                handlePingSuccess(for: hostname, notificationsEnabled: notificationsEnabled)
+                await handlePingSuccess(for: hostname, notificationsEnabled: notificationsEnabled)
                 return true
             } else {
-                handlePingFailure(for: hostname, notificationsEnabled: notificationsEnabled)
+                await handlePingFailure(for: hostname, notificationsEnabled: notificationsEnabled)
                 return false
             }
         } catch {
-            handlePingFailure(for: hostname, notificationsEnabled: notificationsEnabled)
+            await handlePingFailure(for: hostname, notificationsEnabled: notificationsEnabled)
             return false
         }
     }
 
-    private static func handlePingSuccess(for hostname: String, notificationsEnabled: Bool) {
+    private static func handlePingSuccess(for hostname: String, notificationsEnabled: Bool) async {
-        let wasPreviouslyDown = previousPingStates[hostname] == false
+        if let notification = await stateStore.recordSuccess(for: hostname, notificationsEnabled: notificationsEnabled) {
-        previousPingStates[hostname] = true
+            sendNotification(title: notification.title, body: notification.body)
-
-        if wasPreviouslyDown && notificationsEnabled {
-            sendNotification(title: "Server Online", body: "\(hostname) is now online")
         }
     }
 
-    private static func handlePingFailure(for hostname: String, notificationsEnabled: Bool) {
+    private static func handlePingFailure(for hostname: String, notificationsEnabled: Bool) async {
-        let wasPreviouslyUp = previousPingStates[hostname] != false
+        if let notification = await stateStore.recordFailure(for: hostname, notificationsEnabled: notificationsEnabled) {
-        previousPingStates[hostname] = false
+            sendNotification(title: notification.title, body: notification.body)
-
-        if wasPreviouslyUp && notificationsEnabled {
-            sendNotification(title: "Server Offline", body: "\(hostname) is offline")
         }
     }
 
@@ -74,3 +65,55 @@ enum PingService {
         UNUserNotificationCenter.current().add(request)
     }
 }
+
+private actor PingStateStore {
+    private var previousPingStates: [String: Bool] = [:]
+    private var suppressedUntil: [String: Date] = [:]
+
+    func suppressChecks(for hostname: String, duration: TimeInterval) {
+        suppressedUntil[hostname] = Date().addingTimeInterval(duration)
+        previousPingStates[hostname] = false
+    }
+
+    func shouldSkipPing(for hostname: String) -> Bool {
+        if let suppressedUntil = suppressedUntil[hostname], suppressedUntil > Date() {
+            return true
+        }
+
+        suppressedUntil.removeValue(forKey: hostname)
+        return false
+    }
+
+    func recordSuccess(for hostname: String, notificationsEnabled: Bool) -> PingNotification? {
+        let wasPreviouslyDown = previousPingStates[hostname] == false
+        previousPingStates[hostname] = true
+
+        guard wasPreviouslyDown, notificationsEnabled else {
+            return nil
+        }
+
+        return PingNotification(
+            title: "Server Online",
+            body: "\(hostname) is now online"
+        )
+    }
+
+    func recordFailure(for hostname: String, notificationsEnabled: Bool) -> PingNotification? {
+        let wasPreviouslyUp = previousPingStates[hostname] != false
+        previousPingStates[hostname] = false
+
+        guard wasPreviouslyUp, notificationsEnabled else {
+            return nil
+        }
+
+        return PingNotification(
+            title: "Server Offline",
+            body: "\(hostname) is offline"
+        )
+    }
+}
+
+private struct PingNotification {
+    let title: String
+    let body: String
+}

Sources/Views/MainView.swift

@@ -381,14 +381,14 @@ struct MainView: View {
                 api = try await APIFactory.detectAndCreateAPI(baseURL: baseURL, apiKey: apiKey)
             }
             try await api.restartServer(apiKey: apiKey)
-            PingService.suppressChecks(for: server.hostname, duration: 90)
+            await PingService.suppressChecks(for: server.hostname, duration: 90)
 
             return ServerActionFeedback(
                 title: "Reboot Requested",
                 message: "The reboot command was sent to \(server.hostname). The host may become unavailable briefly while it restarts."
             )
         } catch let error as URLError where Self.isExpectedRestartDisconnect(error) {
-            PingService.suppressChecks(for: server.hostname, duration: 90)
+            await PingService.suppressChecks(for: server.hostname, duration: 90)
             return ServerActionFeedback(
                 title: "Reboot Requested",
                 message: "The reboot command appears to have been accepted by \(server.hostname). The connection dropped while the host was going away, which is expected during a reboot."