Threading - Baton Object That Routines Can Pass Around?
Feb 20, 2011
This will no doubt sound like a pretty dumb question to some, but, despite having written many useful single-thread apps over the years, I don't understand enough about threading yet.
Consider this scenario:
There are four modules, each on its own thread, that can happily run concurrently most of the time. However, each module occasionally causes a few seconds' intensive disk activity (by design) and it would be more efficient (faster, less fragmentation) if only one module at a time wrote to the same physical drive.
It would be useful to have something like a baton that modules within a given scope can pass around, perhaps dependent on their respective priority levels.
I am working on a application that has quite a few functions involved and have been thinking of the following: If I have a function that has a few paramaters, is it more efficient to pass the objects to the function(Example 1) or reference the objects in the parent(Example 2)? Does it matter if the objects are large or not?
Example:
Class mainform Public myGenericList As New List(Of String) Public myDatarowArray() As DataRow
We working with a Modem type interface that use's the Comm port for two way communication. The App starts and sets up the Comm port, and sends config info to the 'Modem'. Trick here is you have specific timing issues that need to be considered, and we got it all sorted, by using Threading.
You send The Config command to the modem and wait X ms for the confirmation reply (Single Byte), If no reply, send a Wake up command, wait X ms and send Config command again. Once confirmed that the modem is in config mode, send parameters, Waiting for confirmation of each one. Once config is set, send the 'Return to normal mode' command and wait for confirmation. [Code]
The SwitchModemMode sub runs under the Comms thread and not the main thread, like the Checkmodem sub at the top. Mostly because the Comms thread Raises the Data Event, which in turn calls the SwitchModemMode. Now because of that the Thread that is supposed to be checking for the input and setting the Flag, is actually the one waiting for the Flag to be set. And Yes App.DoEvents could solve it here, however that can/will mess with the Timing needed with these commands. I'm looking for how to pass the Raised event to the Main thread.
So I am currently using the method of combining a timer with a WebBrowser control to constantly check if some particular text has appeared in the WebBrowser control on my form. The text is dynamically generated after some arbitrary amount of time depending on the user's internet connection speed. (I'm using DOM to do this). The code to check for the HtmlElements lies within a function, which is turned called by the timer.
I find that this is kind of crappy and occasionally lags the UI interface, if not making the entire program behave sluggishly. I have been thinking of just using a simple while loop in a worker thread to take care of the issue, but I understand that new threads cannot interact with the UI thread directly (including controls); they have to call wrappers that are present within the UI thread.
So my question is, can you declare a WebBrowser control and still interact with its HTMLDocument properties if you declare it within a worker thread? I don't want the while loop to be executed within the UI thread (by using a wrapper), since that would defeat the purpose. I would also like to avoid DoEvents() as much as possible...unless that's the only way to do this thing?
This code copose from Class including tow sub first sub to insert data in DB Ms access- second code: to check if there is same number of Tel if there is not same number will excute the first code insert, if there is same number of Tel it will show messagebox the problem that I faced is by how to pass object(InsertData) from CheckN sub. It showed me error : Expression is not a method
For example if I have a function call like below Function callingMe() Exit Function
And my Function call is like below SomeObj.callingMe('1','2','3','4','5') // Variable number of arguments Inside callingMe() function, I want to know arguments passed i.e 1,2,3,4,5 and the Object i.e SomeObj in above case.
I am making a simple maze game that you use the arrows keys to navigate. I completed the movement part of it, but now i'm having trouble with the walls. How can you make an object not pass through another and how to tell the program what to do when a object gets to a defined place(the finish)
I have various shape objects, and I want each unique shape to implement a saveToDB method that simply calls a DB object that implements a Save method with an object as its input paramter. This DB.Save method will be a long case function that implements the proper SQL commands based on the type of attributes possessed by the input parameter object.how do I implement the SaveToDB method in my Shape class? Is it something like this:
Function Shape.SaveToDB DB.Save(Me) End Function
The goal here is to let each shape save itself without it knowing anything about database operations; I want to isolate db-specific information in my intermediary DB object, so the DB object will have to figure out what type of object wants to be saved into the SQL database and then execute whatever SQL instructions are needed. And then if I override the SaveToDB method in each shape subclass, I can avoid the case statement entirely, replacing it with a series of unique methods such as db.SaveCircle (ob), db.SaveSquare (ob), etc., sincle the caller already knows what it is.
I'm trying to give a default value to the register property method. This required a function, but passed as an object(delegate?).[code]....
I want to call that registerproperty method, but I don't know how I can do that in VB.net. I just need to pass along a new Person object and I thought this was the way to go[code]....
We have a few applications that will be passing a token object around and I wanted to get an idea about the best approach at doing this.
For starters, this token object is somewhat simple. It would have about 5 properties or so.
Would we create a WCF app and reference it through a datacontract?What about serializing it and sending it through an http post? (each app have a referenced dll of the object)Querystring? (I truly don't think this would be good, but put it up nonetheless)?
I'm writing a wrapper class to expose a subset of the functionality of a .NET FTP library edtftpne from Enterprise Distributed Technologies.
When you call the edtftp's GetFileInfos method you get an array of FTPFile objects returned. I'm able to iterate through these but I don't know how to pass them on as a new and different object array containing only Name and Size for each file. Here's the code I have. Sorry it's a little confusing because I have my own class named FTPFile and the .NET library I'm using also has a class named FTPFile. I'm using both of them here. I should probably change the name of my class just to avoid confusion:
Public Function GetFileList() As FTPFile() Implements IFTP.GetFileList Dim ftpfiles() As EnterpriseDT.Net.Ftp.FTPFile ftpfiles = fCon.GetFileInfos 'Fill object array
[Code]....
I'd just pass on the object array that I'm getting from the GetFileInfos method but COM clients won't have access to the class/object EnterpriseDT.Net.Ftp.FTPFile without me rewriting it, I'm assuming.
I want to wrap up a chunk of HTML render logic in a User Control. Then I want to pass a custom product object (title, thumbnail, id, etc.) to the UserControl that it can use when it renders. Ideally I want to use this in a repeater (or for loop) and pass the current custom product object into the UC.Every example I've seen has been passing through strings on the UC tag but thats not really want I want to do as it means I'll have references everywhere that need updating should we add a new field that needs rendering.
.Net 1 using VB.net (not my first choice for .net so go easy)HTML example to get us going, this would be in the .ascx page:
Yet in my ascs page I get:"Object reference not set to an instance of an object"
Line 1: <%@ Control Language="vb" AutoEventWireup="false" Codebehind="ProductRender.ascx.vb" Inherits="MyApp.ProductRender" TargetSchema="http://schemas.microsoft.com/intellisense/ie5" %> Line 2: <h3> Line 3: <%= myProd.title %> Line 4: </h3>
I have a method called ADD in a class that connects to a database. The database class name is XDB. I also have an object named XXX in it's own separate class with properties.One of the instructions for the Button named ADD click event is:
'Call Add method passing in the XXX object
So this is how I coded:
'declare a variable X as an object instance of XXX Dim X As New XXX[code].....
I know it's wrong since it doesn't add the XXX and the form doesn't close but I don't know what I'm doing wrong.
When I do my form_paint event, I have quite a lot to redraw, so I'm breaking into into severals subs to make it easier to read. I'm passing the 'e' variable into my subs as shown below, is this correct?
Private Sub frmMain_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint DrawMap(e) End Sub Private Sub DrawMap(ByVal e As System.Windows.Forms.PaintEventArgs) End Sub
Am I right in copying that whole 'e as system.windows....' etc line from the form_paint details into my subs details?Just to clarify, the sub will draw directly onto the form.
Dim oMyObject As New MyObject oMyObject.DoSomething("Parameter1","Parameter2")
The "DoSomething" and the two parameters are dynamically provided from another script. They are stored in a string object in this script: sAction & sParameters. My question is how can I dynamically pass the "sAction" to the object oMyObject.For example oMyObject.sAction (where sAction should be the value stored in the sAction string). The example will probably not work. Is there a way to do this? The idea behind is to avoid having to write each function hardcoded, like:
If sAction = "DoSomething" then oMyObject.DoSomething(sParameters) ElseIf sAction = "AnotherThing" then
I 'm new to programming and to vb. So my question could be from misconception about what can i do. How can i pass a string to a "procedure" and get in return a object whith the same name as the string?
I create a object type entity in the main function and would like to pass it to a separate class, do some calculation, and then pass the result back to the main function. But I keep getting errors, can someone point me where I did wrong? It's in windows application[code]...
How do you pass a control (say a textbox) to a function as a parameter in compiled assembly using CodeDom? I've tried passing through the args in the Invoke method but it doesn't work.[code]...
I am writting a VB .net (3.5) applivcation which references a COM object. I can call methods on the COM object fine provided that they don't require any variables to be passed. I have been told that you can only pass a maximum of one varaible to a COM object, I really don't believe that it true
I have a sub that I want to receive a My.Settings object. I don't know, though, which kind of object to use in the declare line of the sub. For example:[code]
I'm currently working on being able to import a DLL written in Fortran into Visual Basic. I've got all the basics down, so now I'm trying to take it a step further. The title basically says it all, but I'll explain what it is I'm trying to do anyways.
For kicks and giggles, let's just assume I want to pass an object that has three double values in it, possibly representing a point in space in three dimensions. In my Fortran method, I want to take that object, print out the x value, then change the x value to 7.5. Here's my Fortran code that does just that.[code]...
I am converting some VB6 code which passed an unknown form object to a class, which then used the passed form object to reference the calling form and direct the data from the class as follows: The Called Class in the class clsGetRecord Public Function Execute(ByRef FRMForm as form) as booleanFRMForm.List1.Additem(SomeData)....Execute = SomeBool End Function The clsGetRecord is used by many different forms which receive data all have objects called List1 as: The Calling Form for the form frmThisFormPrivate function() as booleanDim objRecord as new clsGetRecordbRet = objRecord.Execute(frmThisForm) The passed form object which will receive dataEnd function. Is there any simple way to do this since the calling form object is unknown at design time?
I have a slew of sub routines that I need to use in my software because each website that I will be accessing don't all use the same methods.....go here...click that...go here...click that...etc etc
So I've divided them into sub routines and call them when I need them but the coding is getting so long that it's becoming confusing to keep up with each sub.
Is it possible to place the sub routines into an independent file like a class and then call them from the file when I need them so I can free up some space to code?
