Raising events in multithreaded classes?
I am running a class(gamepad handler) that uses many child threads to check for key input and the like then it raises events to my form to sort out the needed reaction, Is there a way to make the event raises on the same thread as the class itself.
I am currently trying to make a calendar project it has 2 user controls one is the calendar and the other is the calender day control. When the month changes in the calender control I need to raise an event in daycontrol to update any holidays. In the calendar control I have the following code for the event:
Friend Event MonthChanged()
Public Sub New()
' This call is required by the Windows Form Designer.
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I have a console application (VB.NET). When it is started, it spawns worker threads to find work in the database and do the task, then look for the next task (A workflow basically).
The problem that I have is that I have my Event Handler in the main thread that spawns the worker threads. Those workers, if they error, raise an event to a public delegate. However my main thread is not detecting these events, and I cannot figure out how to make it. My intention is to do all logging (text/database), email alerts, and restarting the worker to find another task that is not errored. (This will be expanded in the LogErrorMessage routine and such, for now I am just keeping it a simple Console.Writeline so that I can see if the method is being fired or not)
Here is the code around what I am trying to do:
Logger Class:
Public Delegate Sub LogDelegateError(ByVal Ex As Exception)
Public Class EventLogger
Public Event EventError As LogDelegateError
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I have a windows application which raises a particular event.I need to create a COM callable class whic will allow VB 6.0 to subscribe to this event.I have done a fair amount of research on this and am confused as hell.
View 3 RepliesI'm trying to run a multi-threaded console app in VB and am having thread cross-over. Basically I want to run 5 threads, have them continually access a queue, process, and repeat until there's nothing left. When all threads have processed I want them to do something else.I'm attempting to use SyncLock to prevent multiple threads from accessing but it does not seem to be working.[code]
View 3 RepliesThis is my attempt to create a ObservableCollection in VB that is WPF thread-safe. Can you think of any problems it may have?
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can I call shared events contained in one class from another class?
for example:
logonclass.vb : handles login logic and authenticates against database
logonmanager.vb: hold current user reference and some logon and timeout events
Logon.vb: A form with a submit button.
I would like to do something like this but I can't get the compiler to agree with it
If VerifyEntries() Then
Try
privLvl = LoginClass.AttemptLogin(txtUserName.Text, txtPassword.Text)[code].....
If this isn't the proper way to wire things together let me know so I can learn to structure differently. In my planning it seemed like I was raising a lot of extra duplicate events from my logonclass to my loginmanager class. Then the loginmanager had to raise it again for the main form to see the change event. It got me thinking that if I publicly shared the events and could raise them from wherever then it would cut down on the amount of events I needed in code and the amount of them flying around at runtime.
I want to have a collection of a class which inherits picturebox, with a couple of extra properties, so essentially the same. Only I get an error at runtime saying : 'An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object.' Here Is my code, I know that the error occurs here :
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I have a TAPI program that is very similar to [URL] I have a delegate ...
Delegate
Sub TapiEventCallback(ByVal
dwMessage As TapiEvent,
ByVal dwParam1
[code].....
From my program TAPI will call the number. My problem is that its not raising any events. I really need CallStateChange. I raised it from address and moved it up to my TAPI Manager. I put break points everywhere and I can not get anything to raise.
I'm trying to teach myself how to create multi-threaded applications in Visual Basic Express 2008. I found a page headed "Creating Threads and Passing Data at Start Time" in the Library here -
[url]
However, I can't get any of the examples on that page to run. I pasted the code from an example into a new Project in my IDE but pressing F5 just gives me build errors which I have no idea how to resolve. It's probably something trivial but I can't progress with these examples. Please can somebody tell me what I need to add to get them to run
I am drawing five images in a row. The five are the same thing at five different zoom levels. Therefore, only one of the five will be displayed at any one time, but the others have to be there because there can be over 100 images being displayed on the screen at any one time, and each drawing is quite complicated. If I were to draw them all on the fly, then zooming would require that all 115 images be recreated and redrawn with each zoom. That's painful. To avoid that, I draw all five zoom levels of each image. When the user iteracts with the form, they will be interacting with, at most, two of the images, so when they interact with the form, only two of the 115 have to be redrawn, though those two have to have all five zoom levels drawn, for a total of 10 images.
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I've just completed my first multi-threaded task under windows. Historically I am a VMS Engineer. You could multithread in drivers in VMS but VMS never had formalized threads. Which means it never had applications threads. Threads will become increasing important in the future. I thought this maybe a good time to discuss them. Not having access to sources hurts in terms of the amount of depth one can achieve in Windows. Some of the topics for this thread might be...compute resource regulation, how to do multi-threading and of course things to watch out for.
View 1 RepliesI have 3 classes in 3 separate dll.
1) Class "BaseForm" that inherits from System.Windows.Forms.Form with "MyEvent" declared as Public Event ()
2) Class "MyForm" which inherits from "BaseForm"
3) class "MyClass" which has a public property "ExternalObject" of "BaseForm" type (the private variable is declared WithEvents)
I make the following steps:
1) intercept the Form LOAD event in "BaseForm"
- Instance the class "MyClass", Assign public property "ExternalObject" = Me
- I do a RaiseEvent "MyEvent" in "BaseForm"
2) "MyEvent" is triggered BEFORE in "MyForm"
3) AFTER "MyEvent" is triggered in "MyClass".How Can I Raise event Befor in "MyClass" and then in "MyForm"?
My windows application needs to raise an event in a COM callable assembly so unmanaged code can pick up on the event.I am sick of this. All the crazy tags required for COM callable is doing my head in.
View 1 RepliesI have written a rather complex dll for processing a large volume of data (~4,000,000 records) from an Oracle database. It works well, but takes about 23 hours to run.Since I wrote the code fairly compartmentalized I realized that there are 6 routines that should be able to run concurrently, and I have a multi core processor,I decided to try my first multi-threaded implementation.
In the routine I am working on I am doing no I/O everything is in memory in variables. My data is already in dataTables and hashTables. Most of the data is defined as private in the class scope, but no conflicting updates should happen because the code segments works very distinct portions of the dataTables.The concept is simple, I have 2 routines that need to complete before launching my threads, and one routine that needs to run after all of the threads have completed. Here is what I am trying;
ProcessDXDate()
ProcessHistology()
aryThreads(0) = New Threading.Thread(AddressOf ProcessLaterality)[code].....
I'm using VB.NET. I want to build a large List (Of MyClassOrStructure) that becomes static after its initial population.I'm going to have multiple threads that need to iterate through this list to read data (no writing, inserting, or deleting)
Are there any very bad things that I need to keep an eye out for?
I am trying to create a proxy checker. This is my first attempt at multithreading and it's not going so well, the threads seem to be waiting for one to complete before initializing the next.
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I'm having some trouble creating a multi-client server / client thingy.So far, I've used Atheist's example and allowed the clients to successfully transmit information.However, whenever I send more than 1 message to the server at the same time, the server bugs up and does not receive the message at all. I suspect it has something to do with the DoRead method reading from both clients and stuffing it up or something.
View 13 RepliesI'm creating macrobutton fields in Word by .NET to add fields. I need someway to figure out when a field is copied and pasted. Is there a kind of event which will be reased within Word to .NET?
This is the code to generate the fields:
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General I need to add a field to Word with a given name and a guid and when it's clicked, moved, copied or pasted. I need an event to do something with it.
My application has 1 main form and three other forms which raise events to my main form. I noticed that the memory starts at 77,000 K and increases substationally over a few hours maby be to 250,000k and ever increases.The main form has a dataset and a bound datagridview which gets refreshed with data. Basically it's a taxi booking application. The booking form raises an event to the main form and the main form refreshes the jobs and displays them on the dgv.
View 8 RepliesI'm trying to write a wrapper to a service, which will be used by an existing VB6 project. I've got most of the basic framework working, except for one important aspect: I can reference the wrapper in a VB6 project and subs/function calls etc. work as expected, but events do not. The events are visible in the VB6 app, but they never fire.
VB.NET Code:
Public Event Action_Response(ByVal Status as String)
Public Function TestEvent()
RaiseEvent Action_Response("Test Done")
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So, the cmdTest button code prints 'Done' as expected, but the Action_Response event doesn't fire. Is there something else do I need to do to get the event to fire?
how to re-write my application (http:[url]....) to be multi-threaded using the background worker. The use case is something like:
1. User opens a binary file, it can be several Gbytes in size so reading it into memory isn't practical.
2. User can then navigate through the file in 188byte chunks, data is read from disk, decoded, and displayed for each chunk in turn.
3. User may want to search for some data or build a report. This will involve repeating the read, decode, display, function multiple times. During this looping the GUI stops responding and there is no option to cancel so I want to make it multi-threaded. So, is it safe to open the file in the GUI thread and then read from the file in the background thread? I currently use something like this to open the file once:
Dim fi As New FileInfo(filepath)
fs = fi.OpenRead()
and then in a separate sub multiple calls to:[code]..........
I've got a multi-threaded app - that is using a global COLLECTION of objects.I'm starting to think that objects - when copied to objects - are really just reference pointers to the "single object" in memory - as they would be in JAVASCRIPT (too many languages At any rate - this code - when taking the object from the collection to work with is it making a new object to play with or is it working the single object that actually resides in the collection?
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I have an application with 4 threads. (GUI, Controller, Producer, Consumer) The GUI is self-explanatory. The controller starts the producer and consumer threads after some intial setup. The producer creates items and places them in a free slot in a "ring buffer". The consumer takes items from the "ring buffer" and writes them to disk. The producer creates items at a much higher rate than the consumer. The consumer is IO heavy and IO bound. Currently I am checking a variable in each ring buffer slot to determine if it can be written to.
if Slot.Free then
Write Slot.Data To Disk
end if
I am not using lock/synclock instead I'm just reading / writing the value of the slot's "free" variable. I don't believe that is correct even though it is a volatile read/write. Is there a better method to read/write this variable? The variable is of type "integer" and is either 0 or 1.
I've been writing multi-threaded applications for a couple of years and have started reading about the Task class. It looks like it handles mutex and synchronous/asynchronous threading in an easier to follow fashion. I was just wondering if you the community likes writing threads the old way or the 4.0 tasking applications. Lastly, I thought multi-threading was parallel computing. But I was reading that there are special task etc. parallel functions.
View 2 Repliesthe question is really what is the correct convention (style) for raising and handling events. When a button is clicked it is generally handled by this method. [Code]
I have recently been trying to follow this convention by creating my own EventArgs class and inheriting the system.eventargs, Then adding my own properties. The problem is as my projects get bigger/complex I seem to be writing multiple eventarg classes. I then decide to try and create a generic eventarg class but this then seemed pointless thinking it would be easier just to pass the object directly instead of wrapping it up in "someEventArg" i have created.
I have a custom (inherited) TabControl which adds Drag/Drop functionality to it, so that one can drag the tabs around, either within the same control (to re-order them) or to and from other TabControls. I've noticed some time ago that my TabControl however was not raising its MouseClick and MouseUp events (or actually: it is not calling its OnMouseClick and OnMouseUp methods, which comes down to the same thing). I've been struggling with this problem for a long while and I finally figured out what is happening. I'm no closer to figuring out what to do about it though... The problem seems related to the drag drop functionality. I have this code in the OnMouseDown method (which is raised as usual):
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I am usng a multi threaded process to fire off a task, but when it is completed I want to make a label visible on the main form (form 1), eg "process completed", however the code I have in place comes up with the following error message;
Cross-thread operation not valid: Control 'lblCompleted' accessed from a thread other than the thread it was created on.
My application takes the currently logged-in user and uses an a DirectoryServices.DirectorySearcher to pull a few additional detail about them (some properties we have stored in a few custom AD fields, as well as their email address). This works great, though I've always though it was a little slow - my single-threaded code could only make about 2-3 requests/second to AD.
The real problem came when I moved this code to a web server. With multiple simultaneous users, the number of requests/second jumps greatly, and the LSASS.EXE process pegs on my server. I've checked the domain controllers, and they're just fine - the bottleneck is clearly on the application side. I suspect that what's slowing my down is the NTLM/Kerberos challenge/response, and the number of simultaneous requests pegs even the multi-core processor.
Our network policy doesn't allow anonymous reads from AD, so that choice is out. Also, I've tried every member of "AuthenticationTypes" (in the example, I'm using .FastBind), but they all seem to have about the same throughput rate with the same load on the processor.how I might work around this restriction and lower my demands on the processor? Here is the code I'm using - pretty straightforward:
Dim sPath As String = "LDAP://" & stringUserDN
Dim entry As New DirectoryEntry(sPath)
entry.AuthenticationType = AuthenticationTypes.FastBind[code]......
I am attempting to test that the event handlers between an interface and controller are wired properly. The system is set up like the example below:
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