Develop Reference

How to check the length of a MSMQ [duplicate]

I was wondering if there is a way to programmatically check how many messages are in a private or public MSMQ using C#? I have code that checks if a queue is empty or not using the peek method wrapped in a try/catch, but I've never seen anything about showing the number of messages in the queue. This would be very helpful for monitoring if a queue is getting backed up.

You can read the Performance Counter value for the queue directly from .NET:
using System.Diagnostics;
// ...
var queueCounter = new PerformanceCounter(
"MSMQ Queue",
"Messages in Queue",
#"machinename\private$\testqueue2");
Console.WriteLine( "Queue contains {0} messages",
queueCounter.NextValue().ToString());

There is no API available, but you can use GetMessageEnumerator2 which is fast enough. Sample:
MessageQueue q = new MessageQueue(...);
int count = q.Count();
Implementation
public static class MsmqEx
{
public static int Count(this MessageQueue queue)
{
int count = 0;
var enumerator = queue.GetMessageEnumerator2();
while (enumerator.MoveNext())
count++;
return count;
}
}
I also tried other options, but each has some downsides
Performance counter may throw exception "Instance '...' does not exist in the specified Category."
Reading all messages and then taking count is really slow, it also removes the messages from queue
There seems to be a problem with Peek method which throws an exception

If you need a fast method (25k calls/second on my box), I recommend Ayende's version based on MQMgmtGetInfo() and PROPID_MGMT_QUEUE_MESSAGE_COUNT:
for C#
https://github.com/hibernating-rhinos/rhino-esb/blob/master/Rhino.ServiceBus/Msmq/MsmqExtensions.cs
for VB
https://gist.github.com/Lercher/5e1af6a2ba193b38be29
The origin was probably http://functionalflow.co.uk/blog/2008/08/27/counting-the-number-of-messages-in-a-message-queue-in/ but I'm not convinced that this implementation from 2008 works any more.

We use the MSMQ Interop. Depending on your needs you can probably simplify this:
public int? CountQueue(MessageQueue queue, bool isPrivate)
{
int? Result = null;
try
{
//MSMQ.MSMQManagement mgmt = new MSMQ.MSMQManagement();
var mgmt = new MSMQ.MSMQManagementClass();
try
{
String host = queue.MachineName;
Object hostObject = (Object)host;
String pathName = (isPrivate) ? queue.FormatName : null;
Object pathNameObject = (Object)pathName;
String formatName = (isPrivate) ? null : queue.Path;
Object formatNameObject = (Object)formatName;
mgmt.Init(ref hostObject, ref formatNameObject, ref pathNameObject);
Result = mgmt.MessageCount;
}
finally
{
mgmt = null;
}
}
catch (Exception exc)
{
if (!exc.Message.Equals("Exception from HRESULT: 0xC00E0004", StringComparison.InvariantCultureIgnoreCase))
{
if (log.IsErrorEnabled) { log.Error("Error in CountQueue(). Queue was [" + queue.MachineName + "\\" + queue.QueueName + "]", exc); }
}
Result = null;
}
return Result;
}

//here queue is msmq queue which you have to find count.
int index = 0;
MSMQManagement msmq = new MSMQManagement() ;
object machine = queue.MachineName;
object path = null;
object formate=queue.FormatName;
msmq.Init(ref machine, ref path,ref formate);
long count = msmq.MessageCount();
This is faster than you selected one.
You get MSMQManagement class refferance inside "C:\Program Files (x86)\Microsoft SDKs\Windows" just brows in this address you will get it. for more details you can visit http://msdn.microsoft.com/en-us/library/ms711378%28VS.85%29.aspx.

I had real trouble getting the accepted answer working because of the xxx does not exist in the specified Category error. None of the solutions above worked for me.
However, simply specifying the machine name as below seems to fix it.
private long GetQueueCount()
{
try
{
var queueCounter = new PerformanceCounter("MSMQ Queue", "Messages in Queue", #"machineName\private$\stream")
{
MachineName = "machineName"
};
return (long)queueCounter.NextValue();
}
catch (Exception e)
{
return 0;
}
}

The fastest method I have found to retrieve a message queue count is to use the peek method from the following site:
protected Message PeekWithoutTimeout(MessageQueue q, Cursor cursor, PeekAction action)
{
Message ret = null;
try
{
ret = q.Peek(new TimeSpan(1), cursor, action);
}
catch (MessageQueueException mqe)
{
if (!mqe.Message.ToLower().Contains("timeout"))
{
throw;
}
}
return ret;
}
protected int GetMessageCount(MessageQueue q)
{
int count = 0;
Cursor cursor = q.CreateCursor();
Message m = PeekWithoutTimeout(q, cursor, PeekAction.Current);
{
count = 1;
while ((m = PeekWithoutTimeout(q, cursor, PeekAction.Next)) != null)
{
count++;
}
}
return count;
}

This worked for me. Using a Enumarator to make sure the queue is empty first.
Dim qMsg As Message ' instance of the message to be picked
Dim privateQ As New MessageQueue(svrName & "\Private$\" & svrQName) 'variable svrnme = server name ; svrQName = Server Queue Name
privateQ.Formatter = New XmlMessageFormatter(New Type() {GetType(String)}) 'Formating the message to be readable the body tyep
Dim t As MessageEnumerator 'declared a enumarater to enable to count the queue
t = privateQ.GetMessageEnumerator2() 'counts the queues
If t.MoveNext() = True Then 'check whether the queue is empty before reading message. otherwise it will wait forever
qMsg = privateQ.Receive
Return qMsg.Body.ToString
End If

If you want a Count of a private queue, you can do this using WMI.
This is the code for this:
// You can change this query to a more specific queue name or to get all queues
private const string WmiQuery = #"SELECT Name,MessagesinQueue FROM Win32_PerfRawdata_MSMQ_MSMQQueue WHERE Name LIKE 'private%myqueue'";
public int GetCount()
{
using (ManagementObjectSearcher wmiSearch = new ManagementObjectSearcher(WmiQuery))
{
ManagementObjectCollection wmiCollection = wmiSearch.Get();
foreach (ManagementBaseObject wmiObject in wmiCollection)
{
foreach (PropertyData wmiProperty in wmiObject.Properties)
{
if (wmiProperty.Name.Equals("MessagesinQueue", StringComparison.InvariantCultureIgnoreCase))
{
return int.Parse(wmiProperty.Value.ToString());
}
}
}
}
}
Thanks to the Microsoft.Windows.Compatibility package this also works in netcore/netstandard.

The message count in the queue can be found using the following code.
MessageQueue messageQueue = new MessageQueue(".\\private$\\TestQueue");
var noOFMessages = messageQueue.GetAllMessages().LongCount();

Duplicate entries on server response .net

Scenario
One windows service polls a url every two minutes to retrieve certain data.
If any data has been added since the previous call, the data is retrieved and stored otherwise the loop carries on.
Issue
Sometimes a request takes more than two minutes to return a response.
When this happens, the next request is still made and finds new data, since the previous request hasn't return a response yet
This results in duplicate entries when the data is stored.
What I've tried
I tried to handle that by using a boolean like so:
Boolean InProgress = true;
foreach (var item in Lists)
{
\\Make a request and return new data (if any)
InProgress = false;
if (InProgress = false)
{
\\Store new data
}
}
This doesn't solve the issue. I believe I'm using the boolean in wrong place, but I'm not sure where it should.
This is the loop that makes the request and store the data
void serviceTimer_Elapsed(object sender, ElapsedEventArgs e)
{
try
{
Data getCredentials = new Data();
DataTable credentials = getCredentials.loadCredentials();
Boolean InProgress = true;
for (int i = 0; i < credentials.Rows.Count; i++)
{
if (credentials != null)
{
var PBranchID = (int)credentials.Rows[i]["PortalBranchID"];
var negRef = (int)credentials.Rows[i]["NegotiatorRef"];
var Username = credentials.Rows[i]["Username"].ToString();
var Password = credentials.Rows[i]["Password"].ToString();
var Domain = credentials.Rows[i]["Domain"].ToString();
var FooCompanyBaseUrl = "https://" + Domain + ".FooCompany.com/";
Data getCalls = new Data();
DataTable calls = getCalls.loadCalls(PBranchID);
//If it's not the first call
if (calls != null && calls.Rows.Count > 0)
{
//Makes a call
DateTime CreatedSince = DateTime.SpecifyKind((DateTime)calls.Rows[0]["LastSuccessOn"], DateTimeKind.Local);
string IssueListUrl = FooCompany.WebApi.V2.URLs.Issues(BaseUrl, null, CreatedSince.ToUniversalTime(), null);
FooCompany.WebApi.V2.DTO.PrevNextPagedList resultIssueList;
resultIssueList = FooCompany.WebApi.Client.Helper.Utils.Getter<Foocompany.WebApi.V2.DTO.PrevNextPagedList>(IssueListUrl, Username, Password);
InProgress = false;
if (InProgress == false)
{
if (resultIssueList.Items.Count > 0)
{
//If call returns new issues, save call
Data saveCalls = new Data();
saveCalls.saveCalls(PBranchID);
foreach (var item in resultIssueList.Items)
{
var Issue = FooCompany.WebApi.Client.Helper.Utils.Getter<FooCompany.WebApi.V2.DTO.Issue>(item, Username, Password);
string TenantSurname = Issue.Surname;
string TenantEmail = Issue.EmailAddress;
Data tenants = new Data();
int tenantPropRef = Convert.ToInt32(tenants.loadTenantPropRef(PBranchID, TenantSurname, TenantEmail));
Data Properties = new Data();
DataTable propAddress = Properties.loadPropAddress(PBranchID, tenantPropRef);
var Address1 = propAddress.Rows[0]["Address1"];
var Address2 = propAddress.Rows[0]["Address2"];
var AddressFolder = Address1 + "," + Address2;
if (!Directory.Exists("path"))
{
Directory.CreateDirectory("path");
}
string ReportPDFDestination = "path";
if (File.Exists(ReportPDFDestination))
{
File.Delete(ReportPDFDestination);
}
FooCompany.WebApi.Client.Helper.Utils.DownloadFileAuthenticated(FooCompany.WebApi.V2.URLs.IssueReport(BaseUrl, Issue.Id), Username, Password, ReportPDFDestination);
//Store data
}
IssueListUrl = resultIssueList.NextURL;
}
}
}
else
{
continue;
}
}
}
catch (Exception ex)
{
//write to log
}
}
Question
I'm sure there is a better way than a boolean.
Could anyone advice a different method to handle the issue properly?
Thanks.
Solution
I ended up using a combination of both Thomas and Mason suggestions. I wrapped a lock statement around the main function of my windows service and used a boolean inside the function section that makes the call to the remote server.
Tested many times and it's error free.

You seems to have a problem of synchronisation, just surround the code that iterate though the List with a lock, and you will be fine.
public class MyClass{
private readonly object internalLock= new object();
private bool AlreadyRunning { get; set; }
void serviceTimer_Elapsed(object sender, ElapsedEventArgs e)
{
if(AlreadyRunning){
return;
}
try{
lock(internalLock){
Thread.MemoryBarrier();
if(AlreadyRunning){
return;
}
AlreadyRunning = true;
...Do all the things...
}
}
catch(Exception e){
..Exception handling
}
finally
{
AlreadyRunning = false;
}
}

bool InProgress=false;
void serviceTimer_Elapsed(object sender, ElapsedEventArgs e)
{
if(!InProgress)
{
InProgress=true;
//retrieve data
InProgress=false;
}
}
Your InProgress variable needs to be declared outside the event handler. When you enter the method, check to see if it's already running. If it is, then we do nothing. If it's not running, then we say it's running, retrieve our data, then reset our flag to say we've finished running.
You'll probably need to add appropriate locks for thread safety, similar to Thomas's answer.

Trying to deserialize more than 1 object at the same time

Im trying to send some object from a server to the client.
My problem is that when im sending only 1 object, everything works correctly. But at the moment i add another object an exception is thrown - "binary stream does not contain a valid binaryheader" or "No map for object (random number)".
My thoughts are that the deserialization does not understand where the stream starts / ends and i hoped that you guys can help me out here.
heres my deserialization code:
public void Listen()
{
try
{
bool offline = true;
Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Normal,
new Action(() => offline = Offline));
while (!offline)
{
TcpObject tcpObject = new TcpObject();
IFormatter formatter = new BinaryFormatter();
tcpObject = (TcpObject)formatter.Deserialize(serverStream);
if (tcpObject.Command == Command.Transfer)
{
SentAntenna sentAntenna = (SentAntenna)tcpObject.Object;
int idx = 0;
foreach (string name in SharedProperties.AntennaNames)
{
if (name == sentAntenna.Name)
break;
idx++;
}
if (idx < 9)
{
PointCollection pointCollection = new PointCollection();
foreach (Frequency f in sentAntenna.Frequencies)
pointCollection.Add(new Point(f.Channel, f.Intensity));
SharedProperties.AntennaPoints[idx] = pointCollection;
}
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message); // raise an event
}
}
serialization code:
case Command.Transfer:
Console.WriteLine("Transfering");
Thread transfer = new Thread(new ThreadStart(delegate
{
try
{
string aName = tcpObject.Object.ToString();
int indx = 0;
foreach (string name in names)
{
if (name == aName)
break;
indx++;
}
if (indx < 9)
{
while (true) // need to kill when the father thread terminates
{
if (antennas[indx].Frequencies != null)
{
lock (antennas[indx].Frequencies)
{
TcpObject sendTcpObject = new TcpObject();
sendTcpObject.Command = Command.Transfer;
SentAntenna sa = new SentAntenna(antennas[indx].Frequencies, aName);
sendTcpObject.Object = sa;
formatter.Serialize(networkStream, sendTcpObject);
}
}
}
}
}
catch (Exception ex) { Console.WriteLine(ex); }
}));
transfer.Start();
break;

Interesting. There's nothing particularly odd in your serialization code, and I've seen people use vanilla concatenation for multiple objects in the past, although I've actually always advised against it as BinaryFormatter does not explicitly claim this scenario is OK. But: if it isn't, the only thing I can suggest is to implement your own framing; so your write code becomes:
serialize to an empty MemoryStream
note the length and write the length to the NetworkStream, for example as a simple fixed-width 32-bit network-byte-order integer
write the payload from the MemoryStream to the NetworkStream
rinse, repeat
And the read code becomes:
read exactly 4 bytes and compute the length
buffer that many bytes into a MemoryStream
deserialize from the NetworkStream
(Noting in both cases to set the MemoryStream's position back to 0 between write and read)
You can also implement a Stream-subclass that caps the length if you want to avoid a buffer when reading, bit that is more complex.

apperantly i came up with a really simple solution. I just made sure only 1 thread is allowed to transfer data at the same time so i changed this line of code:
formatter.Serialize(networkStream, sendTcpObject);
to these lines of code:
if (!transfering) // making sure only 1 thread is transfering data
{
transfering = true;
formatter.Serialize(networkStream, sendTcpObject);
transfering = false;
}

Optimization of file read in C#

I have a requirement to copy a file, parse it's contents removing the line breaks, and the splitting the content along the pipes, and then storing the resulting string[] off in the database. My files could get as large as 65000 valid records each, and so performance is essential.
Below is what I currently have. Problem is it is extremely slow( 3 hours to process 65000 lines). I would appreciate any help with improving optimizing this piece so my runs can be significantly faster.
public void ReadFileLinesIntoRows()
{
try
{
using (var reader = new TextFieldParser(FileName))
{
reader.HasFieldsEnclosedInQuotes = false;
reader.TextFieldType = FieldType.Delimited;
reader.SetDelimiters("|");
String[] currentRow;
while (!reader.EndOfData)
{
try
{
currentRow = reader.ReadFields();
int rowcount = currentRow.Count();
//if it is less than what you need, pad it.
if (rowcount < 190)
{
Array.Resize<string>(ref currentRow, 190);
rows.Add(currentRow);
}
else
{
rows.Add(currentRow);
}
}
catch (MalformedLineException mex)
{
unreadlines.Add(reader.ErrorLine);//continue afterwards
}
}
this.TotalRowCount = rows.Count();
}
}
catch (Exception ex)
{
throw ex;
}
}
public void cleanfilecontent(String tempfilename, Boolean? HeaderIncluded)
{
try
{
//remove the empty lines in the file
using (var sr = new StreamReader(tempfilename))
{
// Write new file
using (var sw = new StreamWriter(CleanedCopy))
{
using (var smove = new StreamWriter(duptempfileremove))
{
string line;
Boolean skippedheader = false;
while ((line = sr.ReadLine()) != null)
{
// Look for text to remove
if (line.Contains("----------------------------------"))
{
smove.Write(line);
}
else if (HeaderIncluded.HasValue && HeaderIncluded.Value==true && ! skippedheader)
{
smove.Write(line);
skippedheader = true;
}
else if(skippedheader)
{
// Keep lines that does not match
sw.WriteLine(line);
}
}
smove.Flush();
}
sw.Flush();
}
sr.Close();
}
}
catch (Exception ex)
{
throw ex;
}
}

65000 records isn't all that big. If you have sufficient memory, I will suggest read the whole file to memory, perform your parsing and construct your row and use batch insert to commit the data to DB. This will be the fastest! I suspect most of your 3 hours is spent in inserting database record one at a time to the database.

C# false http response

I have a thread that returns a site's http response status, but sometimes my program returns false results. and after a while it gives good results.
False result:
it takes a big a mount of time to check, and then it says that (for example) Google is down, which is quite not reasonable, but after a few seconds it returns good results
Can you take a look and tell me whats wrong? or how I can I improve it?
Checks all sites in datagrid:
private void CheckSites()
{
if (CheckSelected())
{
int rowCount = dataGrid.BindingContext[dataGrid.DataSource, dataGrid.DataMember].Count;
string url;
for (int i = 0; i < rowCount; i++)
{
url = dataGrid.Rows[i].Cells[2].Value.ToString();
if (url != null)
{
Task<string[]> task = Task.Factory.StartNew<string[]>
(() => checkSite(url));
// We can do other work here and it will execute in parallel:
//Loading...
// When we need the task's return value, we query its Result property:
// If it's still executing, the current thread will now block (wait)
// until the task finishes:
string[] result = task.Result;
selectRows();
if (result[0] != System.Net.HttpStatusCode.OK.ToString() && result[0] != System.Net.HttpStatusCode.Found.ToString() && result[0] != System.Net.HttpStatusCode.MovedPermanently.ToString())
{
//bad
notifyIcon1.ShowBalloonTip(5000, "Site Down", dataGrid.Rows[i].Cells[2].Value.ToString() + ", has a status code of:" + result, ToolTipIcon.Error);
dataGrid.Rows[i].DefaultCellStyle.BackColor = System.Drawing.Color.Wheat;
TimeSpan ts;
TimeSpan timeTaken = TimeSpan.Parse(result[1]);
dataGrid.Rows[i].Cells[3].Value = result[0];
dataGrid.Rows[i].Cells[3].Style.BackColor = System.Drawing.Color.Red;
dataGrid.Rows[i].Cells[4].Value = timeTaken.Seconds.ToString() + "." + String.Format("{0:0.00000}", timeTaken.Milliseconds.ToString()) + " seconds.";
string sec = (DateTime.Now.Second < 10) ? "0" + DateTime.Now.Second.ToString() : DateTime.Now.Second.ToString();
string min = (DateTime.Now.Minute < 10) ? "0" + DateTime.Now.Minute.ToString() : DateTime.Now.Minute.ToString();
string hour = (DateTime.Now.Hour < 10) ? "0" + DateTime.Now.Hour.ToString() : DateTime.Now.Hour.ToString();
dataGrid.Rows[i].Cells[5].Value = hour + ":" + min + ":" + sec;
//loadbar
}
else if (result[0] == "catch")//catch
{
notifyIcon1.ShowBalloonTip(10000, "SITE DOWN", dataGrid.Rows[i].Cells[1].Value.ToString() + ", Error:" +result[1], ToolTipIcon.Error);
dataGrid.Rows[i].Cells[3].Value = result[1];
dataGrid.Rows[i].Cells[3].Style.BackColor = System.Drawing.Color.Red;
//loadbar
}
else
{
//good
TimeSpan timeTaken = TimeSpan.Parse(result[1]);
dataGrid.Rows[i].Cells[3].Value = result[0];
dataGrid.Rows[i].Cells[3].Style.BackColor = System.Drawing.Color.LightGreen;
dataGrid.Rows[i].Cells[4].Value = timeTaken.Seconds.ToString() + "." + String.Format("{0:0.00000}", timeTaken.Milliseconds.ToString()) + " seconds.";
string sec = (DateTime.Now.Second < 10) ? "0" + DateTime.Now.Second.ToString() : DateTime.Now.Second.ToString();
string min = (DateTime.Now.Minute < 10) ? "0" + DateTime.Now.Minute.ToString() : DateTime.Now.Minute.ToString();
string hour = (DateTime.Now.Hour < 10) ? "0" + DateTime.Now.Hour.ToString() : DateTime.Now.Hour.ToString();
dataGrid.Rows[i].Cells[5].Value = hour + ":" + min + ":" + sec;
//loadbar
}
selectRows();
}
}
}
}
Checks a site:
/////////////////////////////////
////Check datagrid websites-button - returns response
/////////////////////////////////
private string[] checkSite(string url)
{
string[] response = new string[2];
url = dataGrid.Rows[0].Cells[2].Value.ToString();
if (url != null)
{
try
{
HttpWebRequest httpReq;
httpReq.Timeout = 10000;
//loadbar
dataGrid.Rows[0].DefaultCellStyle.BackColor = System.Drawing.Color.Wheat;
System.Diagnostics.Stopwatch timer = new System.Diagnostics.Stopwatch();
timer.Start();
HttpWebResponse httpRes = (HttpWebResponse)httpReq.GetResponse(); //httpRes.Close();
timer.Stop();
//loadbar
HttpStatusCode httpStatus = httpRes.StatusCode;
response[0] = httpStatus.ToString();
response[1] = timer.Elapsed.ToString();//*
httpRes.Close();
return response;
}
catch (Exception he)
{
response[0] = "catch";
response[1] = he.Message;
return response;
}
}
response[0] = "catch";
response[1] = "No URL entered";
return response;
//dataGrid.Rows[i].DefaultCellStyle.BackColor = System.Drawing.Color.Blue;
}
Thanks in advance.

Assuming the code provided is the actual code used:
First of all, your definition of 'False result' and 'Good result' is wrong. If you expect A but get B, that doesn't mean B is invalid. If your wife is giving birth and you expect a boy but it turns out the be a girl, its not a false result. Just unexpected.
That said: lets analyze your work: If it takes a long long time to check a site only to finally get a ??? result which isn't a 200 response code. We can almost savely assume you are dealing with a timeout. If your router, google or any fundamental network device in between is having problems, its expected to get an unexpected answer. "Timeout", "Bad Request", "Server not available" etc. Why would this happen? Its impossible to say for certain without having direct access to your environment.
Looking at your code however, i see that you're using the default TaskScheduler for making each check run as a task in the background (assuming you havent changed the default task scheduler which would be a vey bad practice to begin with). The default task scheduler, schedules each task on the threadpool which results in many many tasks running simultanious. Here we have a good candidate for overloading your network. Many sites (esspecially google) are kinda sensitive for handling many requests from the same source (esspecially if the frequency is high) so maybe google is blocking you temporarily or holding you back. Again, at this point it's pure speculation but the fact that you're running all checks simultaniously (unless the thread pool is on his max) is very likely the cause of your problem.
UPDATE
I would recommend working with a LimitedConcurrencyTaskScheduler ( see here: http://blogs.msdn.com/b/pfxteam/archive/2010/04/09/9990424.aspx ). Here you can limit the amount of tasks that can be run asynchronously. You have to do some testing for what number works ideally in your situation. Also make sure that the frequency is not 'too' high. Its hard to define what is too high, only testing can proof that.

In order to simulate your scenario, I have created a Winform with data grid and a button. On load of the form, I programmatically creates list of url’s (in a table) and bind to data grid. And on button click, we start the download process. In concise, the you have to write more defensive code and the following code only a skeleton of how you can fix the issue.
using System;
using System.Data;
using System.Net;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace app
{
public partial class Form1 : Form
{
DataTable urls = new DataTable();
public Form1()
{
InitializeComponent();
}
//Fill your uri's and bind to a data grid.
void InitTable()
{
//Silly logic to simulate your scenario.
urls = new DataTable();
urls.Columns.Add(new DataColumn("Srl", typeof(string)));
urls.Columns.Add(new DataColumn("Urls", typeof(Uri)));
urls.Columns.Add(new DataColumn("Result", typeof(string)));
DataRow dr = urls.NewRow();
dr["Srl"] = "1";
dr["Urls"] = new Uri("http://www.microsoft.com");
dr["Result"] = string.Empty;
urls.Rows.Add(dr);
dr = urls.NewRow();
dr["Srl"] = "2";
dr["Urls"] = new Uri("http://www.google.com");
dr["Result"] = string.Empty;
urls.Rows.Add(dr);
dr = urls.NewRow();
dr["Srl"] = "3";
dr["Urls"] = new Uri("http://www.stackoverflow.com");
dr["Result"] = string.Empty;
urls.Rows.Add(dr);
urls.AcceptChanges();
}
void UpdateResult()
{
dataGridView1.DataSource = urls;
}
//Important
// This example will freeze UI. You can avoid this while implementing
//background worker or pool with some event synchronization. I haven't covered those area since
//we are addressing different issue. Let me know if you would like to address UI freeze
//issue. Or can do it your self.
private void button1_Click(object sender, EventArgs e)
{
//Create array for Task to parallelize multiple download.
var tasks = new Task<string[]>[urls.Rows.Count];
//Initialize those task based on number of Uri's
for(int i=0;i<urls.Rows.Count;i++)
{
int index = i;//Do not change this. This is to avoid data race
//Assign responsibility and start task.
tasks[index] = new Task<string[]>(
() => checkSite(
new TaskInput(urls.Rows[index]["Urls"].ToString(), urls.Rows[index]["Srl"].ToString())));
tasks[index].Start();
}
//Wait for all task to complete. Check other overloaded if interested.
Task.WaitAll(tasks);
//block shows how to access result from task
foreach (var item in tasks)
{
DataRow[] rows=urls.Select("Srl='"+item.Result[2]+"'");
foreach (var row in rows)
row["Result"]=item.Result[0]+"|"+item.Result[1];
}
UpdateResult();
}
//This is dummy method which in your case 'Check Site'. You can have your own
string[] checkSite(TaskInput input)
{
string[] response = new string[3];
if (input != null)
{
try
{
WebResponse wResponse = WebRequest.Create(input.Url).GetResponse();
response[0] = wResponse.ContentLength.ToString();
response[1] = wResponse.ContentType;
response[2] = input.Srl;
return response;
}
catch (Exception he)
{
response[0] = "catch";
response[1] = he.Message;
response[2] = input.Srl;
return response;
}
}
response[0] = "catch";
response[1] = "No URL entered";
response[2] = input.Srl;
return response;
}
private void Form1_Load(object sender, EventArgs e)
{
InitTable();
UpdateResult();
}
}
//Supply custom object for simplicity
public class TaskInput
{
public TaskInput(){}
public TaskInput(string url, string srl)
{
Url = url;
Srl = srl;
}
public string Srl { get; set; }
public string Url { get; set; }
}
}