Wait for event from SqlListener - c#

I have implemented a SqlListener class that uses SqlDependency to wait for changes in SQL database. At one point in my business workflow I need to wait for a record turning up in the database. The SqlListener triggers an event when requested record is found. This works fine. I can make it work by entering a While-loop and wait until I detect the event being returned. But this is not ideal design. It makes the processor spin a lot in vain.
I would like to wait for the event in a more intelligent manner. I read a lot of suggestions on using Task, NotificationDelegate, ManualResetEvent, etc. .... but I was not able to get it all together.
A simplified example will probably make it easier to understand. This is my current setup that works. But if possible I would like to get rid of the ugly while loop.
private const int MaxWaitTime = 5;
private SqlListener<RecordType> _recordListener;
private RecordType _record;
/// <summary>
/// Request a record and wait until it is found.
/// </summary>
public RecordType GetRecordAwait(int requestedId)
{
// Initiate listening for record
_recordListener = new SqlListener<RecordType>();
_recordListener.SqlModified += SqlListener_SqlModified;
_recordListener.StartListening(requestedId);
// Wait until record is found
var startTime = DateTime.Now;
while (_record == null &&
DateTime.Now.Subtract(startTime).TotalSeconds < MaxWaitTime)
{
Thread.Sleep(1);
}
// Stop listening
_recordListener.SqlModified -= SqlListener_SqlModified;
_recordListener.Dispose();
_recordListener = null;
// Return record
return _record;
}
private void SqlListener_SqlModified(object sender, SqlModifiedArgs args)
{
_record = (RecordType)args.Record;
}

Instead of using While, you could go with Timer and events. Something like:
public class ListenerWaiting
{
public ListenerWaiting(int waitingTimeSeconds)
{
_waitSeconds = waitingTimeSeconds;
}
private int _waitSeconds;
private System.Timers.Timer _timer;
private Listener _listener;
public event EventHandler<string> ListenerDone;
public void Listen(int listeningPeriodSeconds)
{
_listener = new Listener(listeningPeriodSeconds * 1000);
_listener.ListenerCompleted += ListenerListenerCompleted;
_timer = new System.Timers.Timer(_waitSeconds * 1000) {Enabled = true};
_timer.Elapsed += TimerElapsed;
}
void ListenerListenerCompleted(object sender, string e)
{
StopTimer();
StopListener();
if (ListenerDone != null)
ListenerDone(this, "Waiting success! Message was: " + e);
}
void TimerElapsed(object sender, System.Timers.ElapsedEventArgs e)
{
StopTimer();
StopListener();
if (ListenerDone != null)
ListenerDone(this, "Waited longer than set, aborted waiting...");
}
private void StopTimer()
{
_timer.Stop();
_timer.Elapsed -= TimerElapsed;
_timer = null;
}
private void StopListener()
{
_listener.ListenerCompleted -= ListenerListenerCompleted;
_listener = null;
}
}
public class Listener
{
private System.Timers.Timer _timer;
private string _listeningPeriodSeconds;
public event EventHandler<string> ListenerCompleted;
public Listener(int listeningPeriodSeconds)
{
_listeningPeriodSeconds = listeningPeriodSeconds.ToString();
_timer = new System.Timers.Timer(listeningPeriodSeconds) { Enabled = true };
_timer.Elapsed += TimerElapsed;
}
private void TimerElapsed(object sender, System.Timers.ElapsedEventArgs e)
{
_timer.Elapsed -= TimerElapsed;
_timer = null;
if (ListenerCompleted != null)
ListenerCompleted(this, _listeningPeriodSeconds);
}
}
...and then consume it with:
static void Main(string[] args)
{
var wait = new ListenerWaiting(5);
wait.ListenerDone += WaitListenerDone;
wait.Listen(3);
Console.ReadLine();
}
static void WaitListenerDone(object sender, string e)
{
Console.WriteLine(e);
}
I guess I could find better names for classes, but you'll get the idea ;)

In fact the solution was more simple than I first thought. When I rephrased my question and searched again I found it. The ManualResetEvent as mentioned already in my question turned out to be the simplest way to solve it.
All I had to do was to add a ManualResetEvent and set it to wait ;-)
private const int MaxWaitTime = 5000;
private SqlListener<RecordType> _recordListener;
private RecordType _record;
private readonly ManualResetEvent _recordWaiter = new ManualResetEvent(false);
/// <summary>
/// Request a record and wait until it is found.
/// </summary>
public RecordType GetRecordAwait(int requestedId)
{
// Initiate listening for record
_recordListener = new SqlListener<RecordType>();
_recordListener.SqlModified += SqlListener_SqlModified;
_recordListener.StartListening(requestedId);
// Wait synchronously until record is found
_recordWaiter.WaitOne(MaxWaitTime);
// Stop listening
_recordListener.SqlModified -= SqlListener_SqlModified;
_recordListener.Dispose();
_recordListener = null;
// Return record
return _record;
}
private void SqlListener_SqlModified(object sender, SqlModifiedArgs args)
{
_record = (RecordType)args.Record;
_recordWaiter.Set();
}

Related

Questions about unit test

Recently, I am learning unit test and try to use this skill in my project.
However, I have some question about how to test following code.
public class Class1
{
private Timer _timer = new Timer();
public Class1()
{
_timer.Interval = 1000;
_timer.Elapsed += _timer_Elapsed;
}
private void _timer_Elapsed(object sender, ElapsedEventArgs e)
{
//some works
}
public void start()
{
_timer.Start();
//some works
}
public void stop()
{
_timer.Stop();
//some works
}
}
I truly don't know how to test this class without breaking its encapsulation.
Should I expose '_timer_Elapsed' method? Evan if do so, next question comes to how to test method 'start' and 'stop'. Should I use stub object to substitute the Timer in order to test this class? if that, this class will be too complex because I need to make an interface and make a class which encapsulates Timer and implement the interface above.
public interface IEncal
{
double Interval { get; set; }
event ElapsedEventHandler Elapsed;
void Stop();
void Start();
}
public class MyClass : IEncal
{
Timer timer = new Timer();
public double Interval { get { return timer.Interval; } set { timer.Interval = value; } }
public event ElapsedEventHandler Elapsed
{
add { timer.Elapsed += value; }
remove { timer.Elapsed -= value; }
}
public void Start()
{
timer.Start();
}
public void Stop()
{
timer.Stop();
}
}
public class Class1
{
private IEncal _timer;
public Class1(IEncal timer)
{
_timer = timer;
_timer.Interval = 1000;
_timer.Elapsed += _timer_Elapsed;
}
public void _timer_Elapsed(object sender, ElapsedEventArgs e)
{
//some works
}
public void start()
{
_timer.Start();
//some works
}
public void stop()
{
_timer.Stop();
//some works
}
}
Is there any better way to test this class?
The following is the real code I use.
I've written the unit test for ISender class and IInfoProducer class.
Since it's my first time to use unit test, I would like to think about each class for learning.
Back to the question, this class is basically a Timer class. When elapsing ,
it sends a info. So how should I test this timing sending process?
public class InfomationSender
{
private readonly Timer _timer = new Timer();
private readonly ISender _sender;
private readonly IInfoProducer _producer;
public InfomationSender(ISender sender, IInfoProducer producer)
{
_sender = sender;
_producer = producer;
_timer.Interval = 1000;
_timer.Elapsed += _timer_Elapsed;
}
private void _timer_Elapsed(object sender, ElapsedEventArgs e)
{
var info = _producer.getInfo();
_sender.send(info);
}
public void start()
{
_timer.Start();
}
public void stop()
{
_timer.Stop();
_sender.Dispose();
}
}
You should be able test the class without mocking. Less mocking more valuable tests are.
But you didn't provide information about what your code is doing in // some works areas. Because this is what you want to test, timer is just implementation details.
For testing "some works" class should provide some public access to the result of "some works" or result will be "exposed" through injected dependency (repository, logger etc)
Assume class will execute "some work" every second and update Result property after Stop method is called.
public class LiveCalculator
{
private readonly Timer _timer;
private List<int> _allValues
private int _lastSum;
public int LastSum => _lastSum;
public LiveCalculator()
{
_allValues = new List<int>();
_timer = new Timer { Interval = 1000 };
_timer.Elapsed += _timer_Elapsed;
}
private void _timer_Elapsed(object sender, ElapsedEventArgs e)
{
_allValues.Add(42);
}
public void start()
{
_timer.Start();
}
public void stop()
{
_timer.Stop();
_lastResult = _allValues.Sum();
}
}
Tests
[Fact]
public async Task AfterFiveSeconds_LastResultEquals210()
{
var calculator = new LiveCalculator();
calculator.Start();
await Task.Delay(5100);
calculator.Stop();
calculator.LastResult.Should().Be(210);
}

Restart InActivity Monitor after timer is stopped

I have WinForms App where I am using the code in this following Post to check the InActivity Status of my app (Please see the accepted answer in the post). InActivity In WinForms. Once the app reaches inactivity its stopping the inactivity monitor. But then I want to restart the time once the user logs in.
So I have a notification mechanism when the user logs in and I am calling the start timer method again. I get the Started Monitor Message but the app never tracks inactivity and I don't get Timer reporting app is InACTIVE message at all. Please help.
public static System.Windows.Forms.Timer IdleTimer =null;
static int MilliSeconds = 60000;
static void Main(string[] args)
{
f = new GeneStudyForm(true, arguments.SystemTimeOutFolder, arguments.SystemTimeOutFile, StartInActivityMonitor);
int x = StartInActivityMonitor();
}
public static void StartInActivityMonitor()
{
IdleTimer = new Timer();
LeaveIdleMessageFilter limf = new LeaveIdleMessageFilter();
Application.AddMessageFilter(limf);
IdleTimer.Interval = MilliSeconds; //One minute; change as needed
Application.Idle += new EventHandler(Application_Idle);
if (IdleTimer != null)
{
MessageBox.Show(IdleTimer.Interval.ToString());
}
IdleTimer.Tick += TimeDone;
IdleTimer.Tag = InActivityTimer.Started;
MessageBox.Show("starting");
IdleTimer.Start();
}
static private void Application_Idle(object sender, EventArgs e)
{
if (!IdleTimer.Enabled) // not yet idling?
IdleTimer.Start();
}
static private void TimeDone(object sender, EventArgs e)
{
try
{
MessageBox.Show("Stopped");
IdleTimer.Stop(); // not really necessary
f.MonitorDirectory();
f.UpdateInActivityStatus();
IdleTimer.Tick -= TimeDone;
Application.Idle -= new EventHandler(Application_Idle);
}
catch(Exception ex)
{
MessageBox.Show(ex.InnerException + ex.Data.ToString());
}
}
Here is my GeneStudyForm
public partial class GeneStudyForm
{
GeneStudySystemTimeOutIO GeneStudyIO;
Func<int> StartTimer;
//Passing the StartInActivityMonitor Method as Func Delegate
public GeneStudyForm(bool isStandalone, string TimeOutFolder, string TimeOutFile, System.Func<int> MyMethod)
{
GeneStudyIO = GeneStudySystemTimeOutIO.GetInstance(TimeOutFolder, TimeOutFile);
UpdateActivityStatus(AppName.GeneStudyStatus, ActivityStatus.Active);
this.StartTimer = MyMethod;
}
public void UpdateActivityStatus(AppName name, ActivityStatus status)
{
if (GeneStudyIO != null)
{
GeneStudyIO.WriteToFile(name, status);
}
}
public void MonitorDirectory()
{
FileSystemWatcher fileSystemWatcher = new FileSystemWatcher(GeneStudyIO.GetDriectory());
fileSystemWatcher.NotifyFilter = NotifyFilters.LastWrite;
fileSystemWatcher.Filter = "*.json";
fileSystemWatcher.Changed += FileSystemWatcher_Changed;
fileSystemWatcher.EnableRaisingEvents = true;
}
public void UnRegister(FileSystemWatcher fileSystemWatcher)
{
fileSystemWatcher.Changed -= FileSystemWatcher_Changed;
}
// I am writing the inactive status to a file. So this event will fill
private void FileSystemWatcher_Changed(object sender, FileSystemEventArgs e)
{
try
{
var root = GeneStudyIO.GetDesrializedJson();
if (root != null && root.AllApplications != null)
{
var item = root.AllApplications.Any(x => x.Status == ActivityStatus.Active.ToString());
if (!item)
{
if (InActivecount == 0)
{
GeneStudyAndApplicationCommon.TimeStatus = InActivityTimer.Ended;
MessageBox.Show("I am hiding");
this.Hide();
InActivecount++;
}
}
else
{
if (GeneStudyAndApplicationCommon.TimeStatus == InActivityTimer.Ended)
{
MessageBox.Show("I am showing");
this.Show();
UnRegister(sender as FileSystemWatcher);
UpdateActivityStatus(AppName.GeneStudyStatus, ActivityStatus.Active);
MessageBox.Show("Updated Status");
if (StartTimer != null)
{
MessageBox.Show("Starting Timer again");
if (StartTimer() == -1)
{
MessageBox.Show("Couldn't start timer");
}
}
}
}
}
}
catch (Exception ex)
{
SystemDebugLogLogger.LogException(ex);
}
}
}
This soulution is quite different from what I have posted. But I could solve my problem with this. But I want to post it if it helps someone. Here is the post I am following Last User Input
I created a class called IdleCheck where I am getting LastUserInput as follows
public static class IdleCheck
{
[StructLayout(LayoutKind.Sequential)]
private struct LASTINPUTINFO
{
[MarshalAs(UnmanagedType.U4)]
public int cbSize;
[MarshalAs(UnmanagedType.U4)]
public int dwTime;
}
[DllImport("user32.dll")]
private static extern bool GetLastInputInfo(ref LASTINPUTINFO x);
public static int GetLastInputTime()
{
var inf = new LASTINPUTINFO();
inf.cbSize = Marshal.SizeOf(inf);
inf.dwTime = 0;
return (GetLastInputInfo(ref inf)) ? Environment.TickCount - inf.dwTime : 0;
}
}
Next in the actual Form this is my code. I am using a simple yes no message box to see if the timer can be stopped and recalled again when needed. You can apply your own locking mechanism.
I want the app to time out if it is InActive for 20 seconds. Change it as needed.
public partial class Form1 : Form
{
Timer timer;
const int TIMEOUT_DONE = 20000;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
Reset();
}
void timer_Tick(object sender, EventArgs e)
{
//var ms = TIMEOUT_DONE - IdleCheck.GetLastInputTime();
if (IdleCheck.GetLastInputTime() > TIMEOUT_DONE)
{
DialogResult dialogResult = MessageBox.Show("Sure", "Some Title", MessageBoxButtons.YesNo);
if (dialogResult == DialogResult.Yes)
{
Stop();
Reset();
}
}
}
public void Reset()
{
timer = new Timer();
timer.Interval = 10000;
timer.Tick += timer_Tick;
timer.Start();
}
public void Stop()
{
timer.Tick -= timer_Tick;
timer.Stop();
}
}

Timer and Processing Issues in C#

I have a service that processes files. Sometimes they process very quickly and sometimes they take a very long time. I can't control the process that sends the files to me. The are randomly dropped on me throughout the day and night. When I use the timer, it seems like the "ProcessFiles" method is abandoned whereever it is when the time has elapsed and ProcessFiles is called again. Since the files contain sensitive information, they can't sit on the server for a long time so I can't set the timer for any longer than 5 minutes and, still, at 5 minutes, the process sometimes interrupts itself. As a result, I have partially processed files. I would appreciate any thoughts and input on this quandary.
System.Timers.Timer _timer;
// As the files come in, massage them and encrypt them
public const string InPath = #"c:\input";
public const string OutPath = #"\c:\output";
public FileMassaging()
{
InitializeComponent();
}
public EventLog MyEventLog = new EventLog();
public string sSource = "FileMassaging";
public string sLog = "FileMassaging";
protected override void OnStart(string[] args)
{
// Create the source, if it does not already exist.
if (!EventLog.SourceExists(sSource))
EventLog.CreateEventSource(sSource, sLog);
// set up the service
ServiceStatus serviceStatus = new ServiceStatus();
serviceStatus.dwCurrentState = ServiceState.SERVICE_START_PENDING;
serviceStatus.dwWaitHint = 100000;
SetServiceStatus(this.ServiceHandle, ref serviceStatus);
// set up the service
_timer = new System.Timers.Timer();
_timer.Elapsed += new System.Timers.ElapsedEventHandler(this.OnTimer);
_timer.Interval = 5000;
_timer.Start();
// Update the service state to Running.
serviceStatus.dwCurrentState = ServiceState.SERVICE_RUNNING;
SetServiceStatus(this.ServiceHandle, ref serviceStatus);
}
public void OnTimer(object sender, System.Timers.ElapsedEventArgs args)
{
ProcessFiles();
}
public void ProcessFiles()
{
string[] originalFiles = Directory.GetFiles(InPath + #"\", "*.txt");
foreach (string fileName in originalFiles)
{
// Check and process the file
CheckFile(InPath, OutPath, fileName);
}
}
public void CheckFile(string InPath,Outpath, fileName)
{
// for example only -- actual file processing is much longer
//
string infile = InPath+fileName;
string outfile= OutPath+fileName;
File.Move(infile,outfile,true);
}
For testing and extensiblity I would recommend a different overall structure.
First let's seperate out this work into classes where it makes sense. Lets start with a class called FolderWatcher:
public class FolderWatcher
{
private readonly string _inPath;
private readonly string _outPath;
public bool CurrentlyRunning { get; set; }
public FolderWatcher(string inPath, string outPath)
{
_inPath = inPath;
_outPath = outPath;
}
public void TryProcessFiles(object sender, ElapsedEventArgs e)
{
try
{
this.CurrentlyRunning = true;
ProcessFiles(sender, e);
}
catch (Exception)
{
throw;
}
finally
{
this.CurrentlyRunning = false;
}
}
public void ProcessFiles(object sender, ElapsedEventArgs e)
{
string[] originalFiles = GetFilesInDirectory();
foreach (var originalFile in originalFiles)
{
CheckFile(originalFile);
}
}
// Internal/Virtual so that this can mocked in unit testing.
internal virtual string[] GetFilesInDirectory()
{
return Directory.GetFiles(_inPath + #"\", "*.txt");
}
// Internal/Virtual so that this can mocked in unit testing.
internal virtual void CheckFile(string fileName)
{
string infile = $"{_inPath}{fileName}";
string outfile = $"{_outPath}{fileName}";
File.Move(infile, outfile);
}
}
This class has a single responsibility, to move files in response to an event.
Next let's build a class to wrap the FolderWatcher class that handles the timer functionality:
public class TimedFolderWatcher
{
private readonly FolderWatcher _folderWatcher;
private readonly Timer _timer;
public TimedFolderWatcher(FolderWatcher folderWatcher)
{
_folderWatcher = folderWatcher;
InitTimer();
}
private void InitTimer()
{
_timer.Elapsed += new System.Timers.ElapsedEventHandler(this.ProcessFiles);
_timer.Interval = 5000;
_timer.Start();
}
private void ProcessFiles(object sender, ElapsedEventArgs e)
{
_folderWatcher.TryProcessFiles(sender, e);
}
}
This class also has a single responsibility to call the ProcessFiles method every 5000 milliseconds.
Lastly we can init and call these classes this way:
var fileMassageService = new TimedFolderWatcher(new FolderWatcher(#"c:\input", #"c:\output"));
This approach lends itself to testing and follows the best practices of Dependency Injection which will allow you to use an IOC framework in the future if you need to.
From the MSDN Page on Timers try this (https://msdn.microsoft.com/en-us/library/system.timers.timer.interval(v=vs.110).aspx)
_timer = new System.Timers.Timer(5);
_timer.Elapsed += OnTimer;
_timer.AutoReset = true;
// _timer.Start();
_timer.Enable = true;
private static void OnTimer(object sender, System.Timers.ElapsedEventArgs args) { ProcessFiles(); }

Timer act crazy, Resets in different times not as defined

I have this class
public class ResetClock
{
public delegate void ResetFunc();
private ResetFunc m_ResetFunc;
private event ResetFunc Reseted;
private Timer m_Timer;
public ResetClock(int second)
{
double r = second * 1000;
m_Timer = new Timer(r);
m_Timer.AutoReset = false;
m_Timer.Elapsed += new ElapsedEventHandler(onTimerTick);
Reset();
}
public void SetResetMethod(ResetFunc method)
{
m_ResetFunc = method;
}
public void Terminate()
{
m_Timer.Stop();
m_Timer.Dispose();
m_Timer = null;
}
private void onTimerTick(object sender, ElapsedEventArgs e)
{
if (m_ResetFunc == null)
{
if (Reseted != null) Reseted();
}
else
{
m_ResetFunc();
}
Reset();
}
#region Public
public void Reset()
{
m_Timer.Reset();
}
#endregion
}
internal static class TimerEx{
public static void Reset(this Timer timer){
timer.Stop();
timer.Start();
}
}
My application is showing the reset page when this class reaches the seconds defined in the contractor. when a Reset() method calls, the Timer should reset the it self and begin the timer from 0.
for some reason after the application is running few days the reset event is firing after few seconds and not the number of seconds that i defined in the first application initialization
does anyone have any idea....??? I braking my head through the wall to find the answer..

raising events in C# and outputting?

ive been working on a program. i has 3 classes. 2 of the classes have timers that repeat at different intervals and once one "cycle" of the timer is done it raises an event with a string as return. the 3rd class subscribes to the events from the other two timer classes and prints them to screen. it works great!
but my issue is that it prints them separately. say currently the first timer class runs and then raises "hello" every 2 minutes and the other class "dog" every second. then every time an event is raised it prints the raised event to console. i would want it to instead print "hellodog" every second.
i was thinking: so each time a timer fires it will raise an event and update a string in the "output" class with the current value, then make another timer that goes off every second, this timer will read both the updated strings together as one output like "hellodog". is this possible if it is this is the easiest way i think. how would i achieve this idea?
if it is confusing i will clarify.
namespace Final
{
public class Output
{
public static void Main()
{
var timer1 = new FormWithTimer();
var timer2 = new FormWithTimer2();
timer1.NewStringAvailable += new EventHandler<BaseClassThatCanRaiseEvent.StringEventArgs>(timer1_NewStringAvailable);
timer2.NewStringAvailable += new EventHandler<BaseClassThatCanRaiseEvent.StringEventArgs>(timer2_NewStringAvailable);
Console.ReadLine();
}
static void timer1_NewStringAvailable(object sender, BaseClassThatCanRaiseEvent.StringEventArgs e)
{
var theString = e.Value;
//To something with 'theString' that came from timer 1
Console.WriteLine(theString);
}
static void timer2_NewStringAvailable(object sender, BaseClassThatCanRaiseEvent.StringEventArgs e)
{
var theString2 = e.Value;
//To something with 'theString2' that came from timer 2
Console.WriteLine(theString2);
}
}
public abstract class BaseClassThatCanRaiseEvent
{
public class StringEventArgs : EventArgs
{
public StringEventArgs(string value)
{
Value = value;
}
public string Value { get; private set; }
}
//The event itself that people can subscribe to
public event EventHandler<StringEventArgs> NewStringAvailable;
protected void RaiseEvent(string value)
{
var e = NewStringAvailable;
if (e != null)
e(this, new StringEventArgs(value));
}
}
public partial class FormWithTimer : BaseClassThatCanRaiseEvent
{
Timer timer = new Timer();
public FormWithTimer()
{
timer = new System.Timers.Timer(200000);
timer.Elapsed += new ElapsedEventHandler(timer_Tick); // Everytime timer ticks, timer_Tick will be called
timer.Interval = (200000); // Timer will tick evert 10 seconds
timer.Enabled = true; // Enable the timer
timer.Start(); // Start the timer
}
void timer_Tick(object sender, EventArgs e)
{
...
RaiseEvent(gml.ToString());
}
}
public partial class FormWithTimer2 : BaseClassThatCanRaiseEvent
{
Timer timer = new Timer();
public FormWithTimer2()
{
timer = new System.Timers.Timer(1000);
timer.Elapsed += new ElapsedEventHandler(timer_Tick2); // Everytime timer ticks, timer_Tick will be called
timer.Interval = (1000); // Timer will tick evert 10 seconds
timer.Enabled = true; // Enable the timer
timer.Start(); // Start the timer
}
void timer_Tick2(object sender, EventArgs e)
{
...
RaiseEvent(aida.ToString());
}
}
}
You can use the same event handler for both timers. And construct the output by identifying the senders. (Didn't test the code for syntax errors.)
private static string timer1Value = string.Empty;
private static string timer2Value = string.Empty;
private static FormWithTimer timer1;
private static FormWithTimer2 timer2;
public static void Main()
{
timer1 = new FormWithTimer();
timer2 = new FormWithTimer2();
timer1.NewStringAvailable += new EventHandler<BaseClassThatCanRaiseEvent.StringEventArgs>(timer1_NewStringAvailable);
timer2.NewStringAvailable += new EventHandler<BaseClassThatCanRaiseEvent.StringEventArgs>(timer1_NewStringAvailable);
Console.ReadLine();
}
static void timer1_NewStringAvailable(object sender, BaseClassThatCanRaiseEvent.StringEventArgs e)
{
if (sender == timer1)
{
timer1Value = e.Value.ToString();
}
else if (sender == timer2)
{
timer2Value = e.Value.ToString();
}
if (timer1Value != String.Empty && timer2Value != String.Empty)
{
Console.WriteLine(timer1Value + timer2Value);
// Do the string concatenation as you want.
}
When the events are handled in your example they have no access to information about the other events. If you want to have 2 events that update strings, but you want the handler to print data from both updated strings, you need the event handlers to have access to both of those strings. You can either store them in variables on the event handling class, or make them public properties of the classes that are raising the events. That way in either event handler you have access to the updated strings from other events.

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