[Fix] fixes issue where program would get stuck if trying to read data and there was actually no data sent by another XBee

samco182 · samco182 · commit 665712020b93 · 2019-10-02T03:12:35.000-06:00
diff --git a/Examples/RxTxExample/Sources/RxTxExample/main.swift b/Examples/RxTxExample/Sources/RxTxExample/main.swift
@@ -8,7 +8,7 @@ let xbee = SwiftyXBee(for: .RaspberryPi3, serialConnection: serialConnection)
 print("Receiving packet...")
 
 do {
-    let readingPacket = try xbee.readRFDataPacket()
+    let readingPacket = try xbee.readRFDataPacket(maxTimeout: 5) // Wait up to 5 seconds for available data
     print("Packet received: \(readingPacket.frameData.receivedData)")
 } catch let error {
     print("Error receiving packet: \(error)")
diff --git a/Sources/SwiftyXBee/Helpers/Constants.swift b/Sources/SwiftyXBee/Helpers/Constants.swift
@@ -8,6 +8,7 @@
 import Foundation
 
 public enum Constant {
+    public static let defaultReadDataTimeout: Double = 1
     public static let minimumRawDataLength = 4
     public static let startDelimiter: UInt8 = 0x7E
     public static let escapeByteXOR: UInt8 = 0x20
diff --git a/Sources/SwiftyXBee/Helpers/XBeeSerial.swift b/Sources/SwiftyXBee/Helpers/XBeeSerial.swift
@@ -5,10 +5,12 @@
 //  Created by Samuel Cornejo on 7/13/19.
 //
 
+import Foundation
 import SwiftyGPIO
 
 enum XBeeSerialError: Error {
     case checksumFailure
+    case noSerialDataAvailable
 }
 
 public struct XBeeSerial {
@@ -24,12 +26,17 @@ public struct XBeeSerial {
     
     /// Reads all the available bytes in the serial port.
     ///
-    /// - Parameter serial: The serial port to extract data from
+    /// - Parameters:
+    ///   - serial: The serial port to extract data from
+    ///   - maxTimeout: The maximum time to wait for data availability
     /// - Returns: All the bytes extracted from the serial port
     /// - Throws: Serial port reading errors
-    public mutating func readData(from serial: UARTInterface) throws -> [UInt8] {
-        data = []
+    public mutating func readData(from serial: UARTInterface, maxTimeout: TimeInterval) throws -> [UInt8] {
+        let start = Date()
+        while try !serial.hasAvailableData() && abs(start.timeIntervalSinceNow) < maxTimeout { }
+        guard try serial.hasAvailableData() else { throw XBeeSerialError.noSerialDataAvailable }
         
+        data = []
         while try dataIsIncomplete() {
             let readData = serial.readData().map({ UInt8(bitPattern: $0) })
             data += readData
diff --git a/Sources/SwiftyXBee/SwiftyXBee.swift b/Sources/SwiftyXBee/SwiftyXBee.swift
@@ -11,6 +11,7 @@
     import Darwin.C
 #endif
 
+import Foundation
 import SwiftyGPIO
 
 public class SwiftyXBee {
@@ -53,22 +54,24 @@ public class SwiftyXBee {
     
     /// Reads and process an RF data packet.
     ///
+    /// - Parameter maxTimeout: The maximum time to wait before checking the serial port for data
     /// - Returns: A Receive Packet API Frame
     /// - Throws: Any error while reading the RF data packet
-    public func readRFDataPacket() throws -> APIFrame<ZigBeeReceivePacketData> {
-        let rawData = try readSerialData()
+    public func readRFDataPacket(maxTimeout: TimeInterval = Constant.defaultReadDataTimeout) throws -> APIFrame<ZigBeeReceivePacketData> {
+        let rawData = try readSerialData(maxTimeout: maxTimeout)
         let frameData = ZigBeeReceivePacketData(rawData: rawData)
         return try APIFrame(rawData: rawData, frameData: frameData)
     }
     
     /// Reads the transmission status after issuing a Transmit Request API Frame.
     ///
+    /// - Parameter maxTimeout: The maximum time to wait before checking the serial port for data
     /// - Returns: A Transmit Status API Frame
     /// - Throws: Any error while reading the transmit status packet
     /// - Note: If delivery status is 0x00, the transmission was successfully delivered to the destination address.
     ///         Otherwise, the number received in this byte will indicate the kind of issue that prevented the delivery.
-    public func readTransmitStatus() throws -> APIFrame<ZigBeeTransmitStatusData> {
-        let rawData = try readSerialData()
+    public func readTransmitStatus(maxTimeout: TimeInterval = Constant.defaultReadDataTimeout) throws -> APIFrame<ZigBeeTransmitStatusData> {
+        let rawData = try readSerialData(maxTimeout: maxTimeout)
         let frameData = ZigBeeTransmitStatusData(rawData: rawData)
         return try APIFrame(rawData: rawData, frameData: frameData)
     }
@@ -88,20 +91,22 @@ public class SwiftyXBee {
     
     /// Reads and process an AT Command response
     ///
+    /// - Parameter maxTimeout: The maximum time to wait before checking the serial port for data
     /// - Returns: An AT Command Response Frame
     /// - Throws: Any error while reading the RF data packet
-    public func readATCommandResponse() throws -> APIFrame<ATCommandResponseData> {
-        let rawData = try readSerialData()
+    public func readATCommandResponse(maxTimeout: TimeInterval = Constant.defaultReadDataTimeout) throws -> APIFrame<ATCommandResponseData> {
+        let rawData = try readSerialData(maxTimeout: maxTimeout)
         let frameData = ATCommandResponseData(rawData: rawData)
         return try APIFrame(rawData: rawData, frameData: frameData)
     }
     
     /// Reads the serial port.
     ///
+    /// - Parameter maxTimeout: The maximum time to wait before checking the serial port for data
     /// - Returns: All the available data in the serial port
-    /// - Throws:  Any errors while reading the serial port
-    public func readSerialData() throws -> [UInt8] {
-        return try serial.readData(from: uart)
+    /// - Throws: Any errors while reading the serial port
+    public func readSerialData(maxTimeout: TimeInterval = Constant.defaultReadDataTimeout) throws -> [UInt8] {
+        return try serial.readData(from: uart, maxTimeout: maxTimeout)
     }
     
     /// Writes data to the serial port.
