for datagram connections, apply backoff to receiving keepAlive

PADL · Nov 27, 2024 · 616bbce · 616bbce
1 parent 3ff7417
commit 616bbce
Showing 1 changed file with 38 additions and 14 deletions.
diff --git a/Sources/SwiftOCA/OCP.1/Ocp1Connection+Connect.swift b/Sources/SwiftOCA/OCP.1/Ocp1Connection+Connect.swift
@@ -260,24 +260,16 @@ extension Ocp1Connection {
     options.flags.contains(.automaticReconnect)
   }
 
-  /// reconnect to the OCA device with exponential backoff, updating
-  /// connectionState
-  func reconnectDeviceWithBackoff() async throws {
+  private func _withExponentialBackoffPolicy(
+    _ body: () async throws -> ()
+  ) async throws {
     var lastError: Error?
     var backoff: Duration = options.reconnectPauseInterval
 
-    _updateConnectionState(.reconnecting)
-
-    logger
-      .trace(
-        "reconnecting: pauseInterval \(options.reconnectPauseInterval) maxTries \(options.reconnectMaxTries) exponentialBackoffThreshold \(options.reconnectExponentialBackoffThreshold)"
-      )
-
     for i in 0..<options.reconnectMaxTries {
       do {
         logger.trace("reconnecting: attempt \(i + 1)")
-        try await _connectDeviceWithTimeout()
-        try await _didConnectDevice()
+        try await body()
         lastError = nil
         break
       } catch {
@@ -292,9 +284,41 @@ extension Ocp1Connection {
 
     if let lastError {
       logger.debug("reconnection abandoned: \(lastError)")
-      _updateConnectionState(lastError.ocp1ConnectionState)
       throw lastError
-    } else if !isDatagram && !isConnected {
+    }
+  }
+
+  /// reconnect to the OCA device with exponential backoff, updating
+  /// connectionState
+  func reconnectDeviceWithBackoff() async throws {
+    _updateConnectionState(.reconnecting)
+
+    logger
+      .trace(
+        "reconnecting: pauseInterval \(options.reconnectPauseInterval) maxTries \(options.reconnectMaxTries) exponentialBackoffThreshold \(options.reconnectExponentialBackoffThreshold)"
+      )
+
+    do {
+      try await _withExponentialBackoffPolicy {
+        try await _connectDeviceWithTimeout()
+        try await _didConnectDevice()
+      }
+
+      // for datagram connections, the connection isn't truly open until we have sent a keepAlive
+      // packet and received a response. restart the exponential backoff policy awaiting a PDU.
+      if isDatagram {
+        try await _withExponentialBackoffPolicy {
+          guard _connectionState.value != .connected else { return }
+          try await sendKeepAlive()
+          throw Ocp1Error.missingKeepalive
+        }
+      }
+    } catch {
+      _updateConnectionState(error.ocp1ConnectionState)
+      throw error
+    }
+
+    if !isConnected {
       logger.trace("reconnection abandoned after too many tries")
       _updateConnectionState(.notConnected)
       throw Ocp1Error.notConnected