Java, C#, VB: Write Thread Safety Functions Without Relying On Native Implementations?
Apr 24, 2011
is it ever possible to write locking-features(for threading) with the language itself (this question is purely academic, I know no one will ever do it even if its possible (not me))?
A) In Java, is it possible to write thread safety functions with java alone, but without using any of the provided classes/language elements/syntax which offer this feature?
B) In C#, is it possible to write thread safety functions with C# alone, but without using any of the provided classes/language elements/syntax which offer this feature?
C) In Vb, is it possible to write thread safety functions with Vb alone, but without using any of the provided classes/language elements/syntax which offer this feature?
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Apr 15, 2012
I've only used type inference when using LINQ in VB.NET. However, I'm aware that type inference can be used in other parts of the language, as demonstrated below:
Dim i = 1 'i is inferred to be an Integer
Dim s = "Hoi" 's is inferred to be a string
Dim Temperatures(10) as Double
[code]....
I can see how type inference reduces the amount of typing I would need to write a piece of code and can also make it quicker to change the type of a base variable (such as Temperatures(10) above) as you wouldn't need to change the types of all other variables that access it (such as T). However, I was concerned that the lack of an explicit declaration of type might make the code harder to read, say during a code inspection, as it may not be immediately obvious what type a variable is. For example, by looking at just the For loop above, you might correclty assume that T is some floating point value, but wouldn't be able to tell if it's single- or double-precision without looking back at the declaration of Temperatures. Depending on how the code is written, Temperatures could be declared much earlier and would thus require the reader to go back and find the declaration and then resume reading. Admittedly, when using a good IDE, this is not so much of an issue, as a quick hover of the mouse cursor over the variable name reveals the type.
Also, I would imagine that using type inference in some situations could introduce some bugs when attempting to change the code. Consider the following (admittedly contrived) example, assuming that the classes A and B do completely different things.
Class A
Public Sub DoSomething()
End Sub
End Class
[code]....
It is possible to change the type of ObjectList from A to B and the code would compile, but would function differently, which could manifest as a bug in other parts of the code.With some examples of type inference, I would imagine that most people would agree that its use has no negative affect on readability or maintainability. For example, in Java 7, the following can be used:
ArrayList<String> a = new ArrayList<>(); // The constructor type is inferred from the declaration.
instead of
ArrayList<String> a = new ArrayList<String>();
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Nov 17, 2009
Lets say we have this code that runs in the constructor:
Dim initVectorBytes As Byte() = System.Text.Encoding.ASCII.GetBytes(initVector)
Dim saltValueBytes As Byte() = System.Text.Encoding.ASCII.GetBytes(saltValue)
Dim passPharse As String = GenerateKeyString(EncryptionKey)
Dim password As Rfc2898DeriveBytes = New Rfc2898DeriveBytes(passPharse, saltValueBytes, passwordIterations)
Dim keyBytes As Byte() = password.GetBytes(CInt(keySize / 8))
mSymmetricKey = New RijndaelManaged()
[Code]...
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Feb 2, 2007
I have a multi-threaded application with several datasets that are read/written to from a couple threads. I have read that datasets can handle multiple readers and one writer. I have synclocks around all dataset writes and no synchronization around reads. I am experiencing random "Index was outside the bounds of the array." exceptions where a dataset item is in a conditional statement, for example:
[Code]...
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Nov 8, 2011
We had plan to create a three tiered architecture database application, where the middle tier will be implemented using Web Service. We're going to use Linux for the server, so I think for the web service to be able to be implemented, we only had PHP/Java left. Is this right?
The constraint is, we're going to use VB.NET for the client application.We already had a two tiered VB.NET application from our last successfull database application. It use a lot of DataSet for the result of SQL execution. Now, what I had in mind, is a simple approach of converting all procedure that return a DataSet Object, to be a WebService method. But, because of this thinking, I don't think we can do it in Java/PHP. That is, we'll be enforce to use a ASP.NET approach. Is this correct? I assume my answer from this article Consuming a DataSet from an XML Web Service (ADO.NET)
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Jul 25, 2011
I have a Console app that loops through a queue and processes each record in a datatable. Each process is long and time-consuming (connecting to a remote website, downloading files, reading them and adding them to the database). I'm trying to implement threading for speed's sake but am having cross-threading issues. (The job takes 8 hours or so to run and the cross-threading doesn't start happening until a couple hours into the run.)I'm trying to figure out how to make my code thread safe. I don't update or rely on any non-local variables, and I don't need to return anything. I've tried locking which works but defeats the purpose of the multiple threads. What other things should I be looking for?
[code]...
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Mar 4, 2009
I'm creating a Client Server application which involves theServer running some scripts in clients and getting back results in an automated way. In Server, other than Main thread, i have 2 worker threads, a) one monitoring response from clients and b) the other scheduling next available job to respective client which executes that job. The issue here is ,I want these worker threads to write the status of their work in the UI(which comes under Main Thread). Also i need to write things in worker thread in a Data table and Rich Text Box in Main thread. But, I can't do so, since it has been blocked to access one thread's function or property directly from others. Is there any work around to do this?
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Jun 13, 2009
I'm trying to make a vb.net application that has got 2 textboxes, 7 radio buttons and 2 buttons(one named compile and the other 'run'). How can I load the content of a C/C++(or any programming language) file into the 1st textbox and on clicking the compile button, i should be able to show the errors or the C/C++ program in the 2nd textbox. On clicking Run, I should be able to show the output in the 2nd textbox. In short, I want to use the 2nd textbox as a terminal/console. The radio buttons are 4 selecting the language C or C++ or python or C# or java or perl or vb.R d compilers of all these languages present in .net?
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Jul 2, 2010
Even though there are many examples of Invoke operations, I can't find something that works for me. (I'm using VS 2008, and working in VB)Here is what i have:
A main module with functions (thread 1) that starts a BeginRead for a TCPClient. When the callback function executes (on thread 3), I want to call a function from the main module, in the main thread. All I get even with Invokes is calling functions that always run in thread 3, not the parent thread.
I call:MsgBox("Function name: " & Thread.CurrentThread.ManagedThreadId)
in each of my functions do determine on what thread it is executed. At some point, from the infinite read callback function I will have to get a function to show a form, but that function gets caught in the callback thread and freezes, instead of running in the main thread.PS: the callback that I pass to the BeginRead of the TCPClient is a function, not a class, so I can't use raise events.All I need is to call a function to run in the main thread (main module) from another thread.
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Sep 13, 2010
I'm building a .NET component that will call an external web service. I used the "Add Service Reference" dialog to add the web service to my component, which generates the code needed to consume the service and adds the settings to the app.config file.I'm testing the component by adding a reference to its DLL from a Console application and calling the appropriate method that creates a new instance of the web service: ... = new MyServiceSoapClient(). However, when I do this, I get the following exception:
InvalidOperationException
Could not find default endpoint element that references contract 'MyServicesSoap' in the ServiceModel client configuration section. This might be because no configuration file was found for your application, or because no endpoint element matching this contract could be found in the client element.This makes sense since the app.config isn't being brought over with the component's DLL. How can I call the web service without having to rely on the settings in the App.Config?
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Jun 20, 2012
Possible Duplicate: How can I create an interface in VBNet with implicit implimentations I'm normally a C# developer and completely new to VB.NET, so be nice with me.;) Let's say that I have this base class:
[Code]....
Is there any way of not having to use these "proxy"-calls to the real method? I haven't found any useful information about this in the CLI-specification, which makes me suspect that this is a VB.NET "feature". Is this the case?
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Aug 11, 2009
I would like to know what are the usages for Threading or BackgroundWorker, and their implementations.I currently am running a UDP program, but the server freezes until the client sends the packet, which momentarily unfreezes the server, and then re freezes it.I have looked at the MSDN for them and they seem complicated :l
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Nov 10, 2010
I am unsure how to write in message box functions for a pop up window. I need OK and Cancel buttons to display with my message box. The Ok button needs to close the message box and the Cancel button to close the entire program. Here is what I have so far
Public Class Form1
Public scoreA, scoreB As Single
Private Sub txtboxa_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtboxa.TextChanged
scoreA = txtboxa.Text
[code]....
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Feb 1, 2012
I am trying to convert a VB.NET project to C#. I am conveting all the forms and classes as required, but I don't know where I need to write the events from ApplicationEvents.vb (I believe its autoGenerated from Properties) Here is the code in my ApplicationEvent.vb file:
[Code]....
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Feb 14, 2011
is it possible to create a form in vb, functions able to create, update or delete records?
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Feb 13, 2010
I have a program and the program works fine. The only thing is that I want to shorten it up and stop using the same code over and over. I use the same redudant code through out the code. I want to write some functions in order to stop from having to use the same code over and over in my program. I wanted to know if someone could help me with functions: Here is part of my code below.
[Code]...
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Jul 18, 2010
need to know exactly how does the API functions Read/Whrite Process works. I'm so confused while working. I know that I have to work using something like sectors. But I don't know how. Can someone give me an example. I dont know hoe to do it. for an example, for you to give me. Create a basic programa with a button and a textbox the button searchs what is in the textbox in a process memory. Search the title of a program for example.
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May 8, 2012
What is the best way to write functions in Microsoft.NET (VB) to avoid memory leaks. I have always followed this style:
Public Sub TestMemoryLeak()
Dim testCon As SqlConnection
Try
[code].....
Here the connection reference is created before the TRY clause and is initialised after the TRY clause. I believe the connection is always closed and dereferenced even if an exception is thrown. Is this good practice? I see a lot of code that creates references and dereferences in the TRY clause, but this would mean that the memory is not correctly handled if an exception is thrown. Some developers say they don't like to clean up in the finally clause.
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Dec 6, 2010
What I am trying to do is have a class where the functions of the same name are both instance functions and shared functions.
Public Shared Function Get...(byval xx as xx)
and
Public Function Get...
The Public Function uses a Property xx created in the constructor, whereas the Shared Function has the parameters (byval xx as xx).
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May 11, 2010
My application works with the sql database. It always connect to the databse using the same login and password written earlier in the application code.I just have a conncetion string with all that data inside.
I know that it is not the safiest way to do that. How to safely hold this thata inside of an application?
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Oct 7, 2010
I've written the following code which works fine.I'm wondering if there is not a simpler way of writing it to achieve the same?
[Code]...
I've not found any other way than using a Timer to have the status updated and the other actions done, as as soon as I start the thread, I loose control and "GetList_Button_Click" does not wait or control the thread.
The goal of using the thread is to not freeze the application and also adding a button to cancel the search in the future.
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Nov 4, 2010
I am using the Interop User Control Toolkit to create a user control for use in a VBA Forms "like" environment. I created a user control and it worked just fine in the environment. The problem that I have is that I get an activex warning upon form load. I need to get rid of this message. I have tried this link with no luck... Although everything compiled file, it crashed my VBAClnt.
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Mar 15, 2012
I've been able to write a thread into my app which basically does a loop in the background perfroming detection for a device being added or removed.works great!i am trying to implement another thread to check for a file on the found device...but i still haven't figured out threading enough to make this work, the versions i try to implemt are either looping along with the initial loop or cancelling itself because its already running.i've been trying to put a variable in that would switch the thread off, but it doesn't seem to work.
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Aug 13, 2010
In one application, I need use 4 simultaneous threads.When the threads finished, I need to update the text of a TextBox.So, I create 4 Textbox, and I wanna the threads change the text to FINISHED.Each thread change one distinct TB.I use this "example"
Dim Terminados As Integer = 0
Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Enabled = True
Timer1.Start()
[code]....
The problem is, I have an error in the red lines.The error is: INVALIDOPERATIONEXCEPTION "Cross-Thread operation not valid: Control tbPlaca1 Accessed from a thread other than the thread it was created on."I don't use cross threading. Each TB only was accessed for the correspondent thread, and for the "main program".
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Nov 3, 2011
This is the error message I am getting:
"Cross-thread operation not valid: Control 'Panel1' accessed from a thread other than the thread it was created on." The reason I am getting this error is because I am opening up a new form and then calling these three things:
Panel1.Show()
Label1.Show()
Label2.Show()
why I get this error message because it doesn't occur normally if I open Form2 after closing Form1, it only occurs when I open Form2 after closing Form4.
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Jul 21, 2009
I have done a program using vb2005 to display reading from my microcontroller bs2 board but have encountered some problems. My code are as follows.
Dim Stop_Rx As Boolean
Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
SerialPort1.Open()
[code]....
I've encounter an error which is, (Cross-thread operation not valid: Control 'txt1' accessed from a thread other than the thread it was created on.)
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Jun 21, 2012
When my client try to connect to server I'm getting this error : Cross-thread operation not valid: Control 'l_users' accessed from a thread other than the thread it was created on.
Private Sub _socketManager_onConnectionAccept(ByVal SocketID As String) Handles _socketManager.onConnectionAccept
l_Users.Items.Add(SocketID)
End Sub
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Feb 17, 2012
Would anyone be able to help me here please. I'm fairly new to VB.net and threading so im just trying to figure out what is happening.When I debug this I am getting the error thread operation not valid: Control 'ProgressBar1' accessed from a thread other than the thread it was created on.
I'm a little lost as to why the error is occuring or how to fix it. I've had to put the progress bar in a separate thread otherwise the GUI crashes
[Code]...
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Jun 23, 2010
I can not fiend any write functions to a text file or to a other file in Windows Direction
I want a simple write function for a button when click button it will write some lines to a file
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Sep 2, 2010
My understanding is that thread.join will suspend the execution of code on the calling thread until the spawned thread finishes or is aborted...
With that in mind, I tried this:
For i = 1 to 50
threads = New Thread(AddressOf test)
threads.IsBackground = True
threads.SetApartmentState(ApartmentState.STA)
[CODE]...
However, the rest of the code runs when the loop finishes, not waiting for all the spawned threads to finish. Since the rest of the code needs the threads to finish (otherwise the rest will error).
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