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  • L2E many to many query

    - by 5YrsLaterDBA
    I have four tables: Users PrivilegeGroups rdPrivileges LinkPrivilege ----------- ---------------- --------------- --------------- userId(pk) privilegeGroupId(pk) privilegeId(pk) privilegeId(pk, fk) privilegeGroupId(fk) name code privilegeGroupId(pk, fk) L2E will not create LinkPrivilege entity for me. So we only have Users, PrivilegeGroups and rdPrivileges entities. PrivilegeGroups and rdPrivileges are many to many relationship. What I need to do is retrieve all code from rdPrivileges table based on a passed in userId. How can I do it? EDIT working code: var acc = from u in db.Users from pg in db.PrivilegeGroups from p in pg.rdPrivileges where u.UserId == userId && u.PrivilegeGroups.PrivilegeGroupId == pg.PrivilegeGroupId select p.Code;

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  • Using ASP.NET MVC, Linq To SQL, and StructureMap causing DataContext to cache data

    - by Dragn1821
    I'll start by telling my project setup: ASP.NET MVC 1.0 StructureMap 2.6.1 VB I've created a bootstrapper class shown here: Imports StructureMap Imports DCS.Data Imports DCS.Services Public Class BootStrapper Public Shared Sub ConfigureStructureMap() ObjectFactory.Initialize(AddressOf StructureMapRegistry) End Sub Private Shared Sub StructureMapRegistry(ByVal x As IInitializationExpression) x.AddRegistry(New MainRegistry()) x.AddRegistry(New DataRegistry()) x.AddRegistry(New ServiceRegistry()) x.Scan(AddressOf StructureMapScanner) End Sub Private Shared Sub StructureMapScanner(ByVal scanner As StructureMap.Graph.IAssemblyScanner) scanner.Assembly("DCS") scanner.Assembly("DCS.Data") scanner.Assembly("DCS.Services") scanner.WithDefaultConventions() End Sub End Class I've created a controller factory shown here: Imports System.Web.Mvc Imports StructureMap Public Class StructureMapControllerFactory Inherits DefaultControllerFactory Protected Overrides Function GetControllerInstance(ByVal controllerType As System.Type) As System.Web.Mvc.IController Return ObjectFactory.GetInstance(controllerType) End Function End Class I've modified the Global.asax.vb as shown here: ... Sub Application_Start() RegisterRoutes(RouteTable.Routes) 'StructureMap BootStrapper.ConfigureStructureMap() ControllerBuilder.Current.SetControllerFactory(New StructureMapControllerFactory()) End Sub ... I've added a Structure Map registry file to each of my three projects: DCS, DCS.Data, and DCS.Services. Here is the DCS.Data registry: Imports StructureMap.Configuration.DSL Public Class DataRegistry Inherits Registry Public Sub New() 'Data Connections. [For](Of DCSDataContext)() _ .HybridHttpOrThreadLocalScoped _ .Use(New DCSDataContext()) 'Repositories. [For](Of IShiftRepository)() _ .Use(Of ShiftRepository)() [For](Of IMachineRepository)() _ .Use(Of MachineRepository)() [For](Of IShiftSummaryRepository)() _ .Use(Of ShiftSummaryRepository)() [For](Of IOperatorRepository)() _ .Use(Of OperatorRepository)() [For](Of IShiftSummaryJobRepository)() _ .Use(Of ShiftSummaryJobRepository)() End Sub End Class Everything works great as far as loading the dependecies, but I'm having problems with the DCSDataContext class that was genereated by Linq2SQL Classes. I have a form that posts to a details page (/Summary/Details), which loads in some data from SQL. I then have a button that opens a dialog box in JQuery, which populates the dialog from a request to (/Operator/Modify). On the dialog box, the form has a combo box and an OK button that lets the user change the operator's name. Upon clicking OK, the form is posted to (/Operator/Modify) and sent through the service and repository layers of my program and updates the record in the database. Then, the RedirectToAction is called to send the user back to the details page (/Summary/Details) where there is a call to pull the data from SQL again, updating the details view. Everything works great, except the details view does not show the new operator that was selected. I can step through the code and see the DCSDataContext class being accessed to update the operator (which does actually change the database record), but when the DCSDataContext is accessed to reload the details objects, it pulls in the old value. I'm guessing that StructureMap is causing not only the DCSDataContext class but also the data to be cached? I have also tried adding the following to the Global.asax, but it just ends up crashing the program telling me the DCSDataContext has been disposed... Private Sub MvcApplication_EndRequest(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.EndRequest StructureMap.ObjectFactory.ReleaseAndDisposeAllHttpScopedObjects() End Sub Can someone please help?

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  • Implement System.Web.Caching.Cache Object in a controller to cache specific query

    - by Julien
    Hello World! I'm Julien and I have a question is it correct to implement my caching object like this in my controller : public class HomeController : BaseController { public static Cache cachingControl = new Cache(); ... And I Use it like this : public ActionResult Home() { IndexViewData view = new IndexViewData(); view.UserId = UserId; if (cachingControl.Get("viewHome") != null) { view = (IndexViewData)cachingControl.Get("viewHome"); } else { view.allAdsList = AllAds(5000, 0); if (Request.QueryString["voirTous"] != null) view.loadGeneral(true); else view.loadGeneral(false); cachingControl.Insert("viewHome", view); } view.adsList = SetupSearch(5, false, 0); return View(view); } But When I Call this line : if (cachingControl.Get("viewHome") != null) { They trow me the error NullErrorException But I know it can be null this is why i'm put this condition to Do you have an alternative or a tips for me thank you! P.S.: I Know that the code is weird :P but I must to support it ... Julien

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  • Django models query

    - by Hulk
    Code: class criteria(models.Model): details = models.CharField(max_length = 512) Headerid = models.ForeignKey(Header) def __unicode__(self): return self.id() the details corresponds to a textarea in the UI and a validation is done for 512 characters but when this is saved. /home/project/django/django/core/handlers/base.py in get_response, line 109 Is this any thing related with schema or number of characters entered from UI

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  • anonymous problem in linq query

    - by ognjenb
    var query2 = from i in proba.id_person select i.id; foreach (var k in query2) { var upit = from l in proba.name join f in proba1.last_name on l.id equals f.id where l.id == k select new { l.ime, f.prezime }; foreach (var g in upit) { model.Add(new ViewModel { Name = g.ime, last_name = g.prezime, id_person = k }); } } return View(model); Why I have this error: The specified LINQ expression contains references to queries that are associated with different contexts.

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  • SQL Query problem: How to merge two lists.

    - by ProfK
    I have a base table of Participants and Answers, with the following structure: ParticipantId, BusUnitId, QuestionNum, Answer. In this table, QuestionNum ranges, say, from 1 to 6. I also have two other tables that sort of link QuestionNum to the actual question table, BusUnitQuestions, and ParticipantQuestions. For each QuestionNum, I must get the actual question text, based on QuestionId. BusUnitId, QuestionId ParticipantId, QuestionId Now assuming records with QuestionNum from 1 to 6. BusUnitQuestions has 3 records, so QuestionNum 1 to 3 must join to Question on the QuestionId's from BusUnitQuestions, and QuestionNum 4 to 6 must join to Question on the QuestionId's from ParticipantQuestions. I assume I need to use ROW_NUMBER() in the subquery from BusUnitQuestions to join to my answer table, but I'm lost after that. If anyone at all understands me, do you have any suggestions?

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  • Theme confusion in SpreadsheetML.

    - by dmaruca
    I've been fighting this all day. Inside my styles.xml file I have color information given like so: <fgColor theme="0" tint="-0.249977111117893" / ECMA 376 defines a theme color reference as: Index into the <clrScheme collection, referencing a particular <sysClr or <srgbClr value expressed in the Theme part. Ok, that sounds easy. Here is an excerpt from my clrScheme xml: <a:clrScheme name="Office" <a:dk1 <a:sysClr val="windowText" lastClr="000000" / </a:dk1 <a:lt1 <a:sysClr val="window" lastClr="FFFFFF" / </a:lt1 Index zero is black, and they are wanting to darken it? I can tell you that after the tint is applied, the color should be #F2F2F2. My confusion is what does theme="0" really mean? It can't possible mean to darken #000000. Checking MSDN only confuses me even more. From http://msdn.microsoft.com/en-us/library/dd560821.aspx note that the theme color integer begins counting from left to right in the palette starting with zero. Theme color 3 is the dark 2 text/background color. Actually, if you start counting at zero the third entry is Light 2. Dark 2 is the second one. Can anyone here shed some light on this subject for me? What does theme="0" really mean? Here is the VB6 code I have been working with to apply the tint. You can paste it into your vba editor and run the test sub. Public Type tRGB R As Byte G As Byte B As Byte End Type Public Type tHSL H As Double S As Double L As Double End Type Sub TestRgbTint() Dim c As tRGB RGB_Hex2Type "ffffff", c RGB_ApplyTint c, -0.249977111117893 Debug.Print Hex(c.R) & Hex(c.G) & Hex(c.B) End Sub Public Sub RGB_Hex2Type(ByVal HexString As String, RGB As tRGB) 'Remove the alpha channel if it exists If Len(HexString) = 8 Then HexString = mID(HexString, 3) End If RGB.R = CByte("&H" & Left(HexString, 2)) RGB.G = CByte("&H" & mID(HexString, 3, 2)) RGB.B = CByte("&H" & Right(HexString, 2)) End Sub Public Sub RGB_ApplyTint(RGB As tRGB, tint As Double) Const HLSMAX = 1# Dim HSL As tHSL If tint = 0 Then Exit Sub RGB2HSL RGB, HSL If tint < 0 Then HSL.L = HSL.L * (1# + tint) Else HSL.L = HSL.L * (1# - tint) + (HLSMAX - HLSMAX * (1# - tint)) End If HSL2RGB HSL, RGB End Sub Public Sub HSL2RGB(HSL As tHSL, RGB As tRGB) HSL2RGB_ByVal HSL.H, HSL.S, HSL.L, RGB End Sub Private Sub HSL2RGB_ByVal(ByVal H As Double, ByVal S As Double, ByVal L As Double, RGB As tRGB) Dim v As Double Dim R As Double, G As Double, B As Double 'Default color to gray R = L G = L B = L If L < 0.5 Then v = L * (1# + S) Else v = L + S - L * S End If If v > 0 Then Dim m As Double, sv As Double Dim sextant As Integer Dim fract As Double, vsf As Double, mid1 As Double, mid2 As Double m = L + L - v sv = (v - m) / v H = H * 6# sextant = Int(H) fract = H - sextant vsf = v * sv * fract mid1 = m + vsf mid2 = v - vsf Select Case sextant Case 0 R = v G = mid1 B = m Case 1 R = mid2 G = v B = m Case 2 R = m G = v B = mid1 Case 3 R = m G = mid2 B = v Case 4 R = mid1 G = m B = v Case 5 R = v G = m B = mid2 End Select End If RGB.R = R * 255# RGB.G = G * 255# RGB.B = B * 255# End Sub Public Sub RGB2HSL(RGB As tRGB, HSL As tHSL) Dim R As Double, G As Double, B As Double Dim v As Double, m As Double, vm As Double Dim r2 As Double, g2 As Double, b2 As Double R = RGB.R / 255# G = RGB.G / 255# B = RGB.B / 255# 'Default to black HSL.H = 0 HSL.S = 0 HSL.L = 0 v = IIf(R > G, R, G) v = IIf(v > B, v, B) m = IIf(R < G, R, G) m = IIf(m < B, m, B) HSL.L = (m + v) / 2# If HSL.L < 0 Then Exit Sub End If vm = v - m HSL.S = vm If HSL.S > 0 Then If HSL.L <= 0.5 Then HSL.S = HSL.S / (v + m) Else HSL.S = HSL.S / (2# - v - m) End If Else Exit Sub End If r2 = (v - R) / vm g2 = (v - G) / vm b2 = (v - B) / vm If R = v Then If G = m Then HSL.H = 5# + b2 Else HSL.H = 1# - g2 End If ElseIf G = v Then If B = m Then HSL.H = 1# + r2 Else HSL.H = 3# - b2 End If Else If R = m Then HSL.H = 3# + g2 Else HSL.H = 5# - r2 End If End If HSL.H = HSL.H / 6# End Sub

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  • Help to translate SQL query to Relational Algebra

    - by Mestika
    Hi everyone, I'm having some difficulties with translating some queries to Relational Algebra. I've a great book about Database Design and here is a chapter about Relational Algebra but I still seem to have some trouble creating the right one: Thoes queries I've most difficuelt with is these: SELECT COUNT( cs.student_id ) AS counter FROM course c, course_student cs WHERE c.id = cs.course_id AND c.course_name = 'Introduction to Database Design' SELECT COUNT( cs.student_id ) FROM Course c INNER JOIN course_student cs ON c.id = cs.course_id WHERE c.course_name = 'Introduction to Database Design' and SELECT COUNT( * ) FROM student JOIN grade ON student.f_name = "Andreas" AND student.l_name = "Pedersen" AND student.id = grade.student_id I know the notation can be a bit hard to paste into HTML forum, but maybe just use some common name or the Greek name. Thanks in advance Mestika

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  • Subsonic 3.0 Query limit with MySQL c#.net LinQ

    - by omegawkd
    Hello, a quick question which may or may not be easily answered. Currently, in order to return a limited result set of data to my calling reference using SubSonic I use a similar function as below: _DataSet = from CatSet in t2_aspnet_shopping_item_category.All() join CatProdAssignedLink in t2_aspnet_shopping_link_categoryproduct.All() on CatSet.CategoryID equals CatProdAssignedLink.CategoryID join ProdSet in t2_aspnet_shopping_item_product.All() on CatProdAssignedLink.ProductID equals ProdSet.ProductID where ProdSet.ProductID == __ProductID orderby CatProdAssignedLink.LinkID ascending select CatSet; and select the first item from the data set. Is there a way to limit the lookup initially to a certain amount of rows? I'm using MySQL as the base database.

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  • using distinct in django query

    - by Hulk
    There is a column as designation in the defaults table,How to get the distinct designation values from defaults table In the below the distinct applies on the id field, this need to be on designation field def = defaults.objects.filter(name=sc).distinct() And can some one explain what is flat=true condition Thanks..

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  • MySQL Query Help, including a count?

    - by nobosh
    Any ideas why this isn't working in MySQL? SELECT blogentry.*, person.personName, (SELECT * FROM BlogEntryComment Where BlogEntryID = '8') as CommentCount FROM blogentry INNER JOIN person ON blogentry.personID = person.personID WHERE blogentry.deleted = 'N' ORDER BY blogentry.dateAdded DESC

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  • My MS Access control displays no text for appended items following an append query

    - by Zaid
    The control in question is part of a datasheet-style subform that feeds off a multi-field combo-box. The control is bound to the first field of the combo box, an ID field which is hidden from view (column width set to zero). Consequently, the second field (Code) is displayed in the control when an item is selected from the combo box. I'm using a form button action to append values to this datasheet. It seems that because I need to INSERT ID values in, the control is unable to display the corresponding Code value. Nothing is visible, unless I go manually into the combo box and select an item from it. How can I get the control to display the Code value?

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  • Regex negative match query

    - by Matt
    Hey guys, I've got a regex issue, Im trying to ignore just the number '41', I want 4, 1, 14 etc to all match. I've got this [^\b41\b] which is effectively what I want but this also ignores all single iterations of the values 1 and 4. As an example, this matches "41", but I want it to NOT match: \b41\b

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  • Add comma-separated value of grouped rows to existing query

    - by Peter Lang
    I've got a view for reports, that looks something like this: SELECT a.id, a.value1, a.value2, b.value1, /* (+50 more such columns)*/ FROM a JOIN b ON (b.id = a.b_id) JOIN c ON (c.id = b.c_id) LEFT JOIN d ON (d.id = b.d_id) LEFT JOIN e ON (e.id = d.e_id) /* (+10 more inner/left joins) */ It joins quite a few tables and returns lots of columns, but indexes are in place and performance is fine. Now I want to add another column to the result, showing comma-separated values ordered by value from table y outer joined via intersection table x if a.value3 IS NULL, else take a.value3 To comma-separate the grouped values I use Tom Kyte's stragg, could use COLLECT later. Pseudo-code for the SELECT would look like that: SELECT xx.id, COALESCE( a.value3, stragg( xx.val ) ) value3 FROM ( SELECT x.id, y.val FROM x WHERE x.a_id = a.id JOIN y ON ( y.id = x.y_id ) ORDER BY y.val ASC ) xx GROUP BY xx.id What is the best way to do it? Any tips?

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  • how to catch ajax query post error?

    - by TTCG
    I would like to catch the error and show the appropriate message if the ajax request fails. My code is like the following, but I could not manage to catch the failure ajax request. function getAjaxData(id) { $.post("status.ajax.php", {deviceId : id}, function(data){ var tab1; if (data.length>0) { tab1 = data; } else { tab1 = "Error in Ajax"; } return tab1; }); } I found out that, "Error in Ajax" is never executed when the Ajax request failed. How to handle the ajax error and show the appropriate message if it fails? Thanks very much.

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  • Windows Service HTTPListener Memory Issue

    - by crawshaws
    Hi all, Im a complete novice to the "best practices" etc of writing in any code. I tend to just write it an if it works, why fix it. Well, this way of working is landing me in some hot water. I am writing a simple windows service to server a single webpage. (This service will be incorperated in to another project which monitors the services and some folders on a group of servers.) My problem is that whenever a request is recieved, the memory usage jumps up by a few K per request and keeps qoing up on every request. Now ive found that by putting GC.Collect in the mix it stops at a certain number but im sure its not meant to be used this way. I was wondering if i am missing something or not doing something i should to free up memory. Here is the code: Public Class SimpleWebService : Inherits ServiceBase 'Set the values for the different event log types. Public Const EVENT_ERROR As Integer = 1 Public Const EVENT_WARNING As Integer = 2 Public Const EVENT_INFORMATION As Integer = 4 Public listenerThread As Thread Dim HTTPListner As HttpListener Dim blnKeepAlive As Boolean = True Shared Sub Main() Dim ServicesToRun As ServiceBase() ServicesToRun = New ServiceBase() {New SimpleWebService()} ServiceBase.Run(ServicesToRun) End Sub Protected Overrides Sub OnStart(ByVal args As String()) If Not HttpListener.IsSupported Then CreateEventLogEntry("Windows XP SP2, Server 2003, or higher is required to " & "use the HttpListener class.") Me.Stop() End If Try listenerThread = New Thread(AddressOf ListenForConnections) listenerThread.Start() Catch ex As Exception CreateEventLogEntry(ex.Message) End Try End Sub Protected Overrides Sub OnStop() blnKeepAlive = False End Sub Private Sub CreateEventLogEntry(ByRef strEventContent As String) Dim sSource As String Dim sLog As String sSource = "Service1" sLog = "Application" If Not EventLog.SourceExists(sSource) Then EventLog.CreateEventSource(sSource, sLog) End If Dim ELog As New EventLog(sLog, ".", sSource) ELog.WriteEntry(strEventContent) End Sub Public Sub ListenForConnections() HTTPListner = New HttpListener HTTPListner.Prefixes.Add("http://*:1986/") HTTPListner.Start() Do While blnKeepAlive Dim ctx As HttpListenerContext = HTTPListner.GetContext() Dim HandlerThread As Thread = New Thread(AddressOf ProcessRequest) HandlerThread.Start(ctx) HandlerThread = Nothing Loop HTTPListner.Stop() End Sub Private Sub ProcessRequest(ByVal ctx As HttpListenerContext) Dim sb As StringBuilder = New StringBuilder sb.Append("<html><body><h1>Test My Service</h1>") sb.Append("</body></html>") Dim buffer() As Byte = Encoding.UTF8.GetBytes(sb.ToString) ctx.Response.ContentLength64 = buffer.Length ctx.Response.OutputStream.Write(buffer, 0, buffer.Length) ctx.Response.OutputStream.Close() ctx.Response.Close() sb = Nothing buffer = Nothing ctx = Nothing 'This line seems to keep the mem leak down 'System.GC.Collect() End Sub End Class Please feel free to critisise and tear the code apart but please BE KIND. I have admitted I dont tend to follow the best practice when it comes to coding.

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  • Linq Query to Update Nested Array Items?

    - by Brett
    I have an object structure generated from xsd.exe. Roughly, it consists of 3 nested arrays: protocols, sources and reports. The xml looks like this: <protocols> <protocol> <source> <report /> <report /> </source> <source> <report /> <report /> </source> </protocol> <!-- more protocols --> </protocols> I need to update a single "Report" within the data structure. A brute force algorithm is shown below. I know that this could be done using XDocument and Linq, but I'd prefer to update the data structure and then serialize the structure back to disk. Thoughts? Brett bool updated = false; foreach (ProtocolsProtocol protocol in protocols.Protocol) { if (updated) break; foreach (ProtocolsProtocolSource source in protocol.Source) { if (updated) break; for (int i = 0; i < source.Report.Length; i++) { ProtocolsProtocolSourceReport currentReport = source.Report[i]; if (currentReport.Id == report.Id) { currentReport.Attribute1 = report.Attribute1; currentReport.Attribute2 = report.Attribute2; updated = true; break; } } } }

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  • Django: testing get query

    - by Brant
    Okay, so I am sick of writing this... res = Something.objects.filter(asdf=something) if res: single = res[0] else: single = None if single: # do some stuff I would much rather be able to do something like this: single = Something.objects.filter(asdf=something) if single: #do some stuff I want to be able to grab a single object without testing the filtered results. In other words, when i know there is either going to be 1 or 0 matching entries, I would like to jump right to that entry, otherwise just get a 'None'. The DoesNotExist error that goes along with .get does not always work so well when trying to compress these queries into a single line. Is there any way to do what I have described?

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  • Convert VB6 to C# use NDDE ? help

    - by tabvn
    i have a vb6 code i want to use http://ndde.codeplex.com/ , please help me convert to c# thanks Const TOPIC_SENSOR As String = "SeeLane|Sensor" Const TOPIC_GATE As String = "SeeLane|Gate" Const TOPIC_PIN As String = "SeeLane|Pin" Const ITEM_SENSOR_ACTIVATE As String = "Activate" Const ITEM_GATE_OPEN As String = "Open" Const ITEM_PIN_ON As String = "On" Const ITEM_PIN_OFF As String = "Off" Private Sub Form_Load() On Error GoTo NO_DDE_SERVER lblCar.LinkMode = vbLinkNotify lblLaneId.LinkMode = vbLinkManual lblName.LinkMode = vbLinkManual lblAuthorized.LinkMode = vbLinkManual lblFile.LinkMode = vbLinkManual lblConfidence.LinkMode = vbLinkManual lblType.LinkMode = vbLinkManual MsgBox "Ket noi voi thanh cong voi SeeLane !!!" Exit Sub NO_DDE_SERVER: MsgBox "Khong the ket noi voi SeeLane !(Xem chuong trinh co chay khong?)." Exit Sub End Sub Private Sub lblCar_LinkNotify() On Error Resume Next lblCar.LinkRequest lblLaneId.LinkRequest lblName.LinkRequest lblAuthorized.LinkRequest lblFile.LinkRequest lblConfidence.LinkRequest lblType.LinkRequest CheckAuthorized lblLaneId.Caption = lblLaneId.Caption + 1 End Sub Private Sub CheckAuthorized() Dim i As Integer i = lblAuthorized.Caption i = i + 1 If lblAuthorized.Caption = 1 Then lblPoke.LinkTopic = TOPIC_GATE lblPoke.LinkItem = ITEM_GATE_OPEN lblPoke = Chr(lblLaneId.Caption) lblPoke.LinkMode = vbLinkManual lblPoke.LinkPoke End If End Sub

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  • DataMapper is only returning the last part of this query

    - by Josh K
    So I'm using the following: $r = new Record(); $r->select('ip, count(*) as ipcount'); $r->group_by('ip'); $r->order_by('ipcount', 'desc'); $r->limit(5); $r->get(); foreach($r->all as $record) { echo($record->ip." "); echo($record->ipcount." <br />"); } And I only get the last (fifth) record echo'ed out and no ipcount echoed. Is there a different way to go around this? I'm working on learning DataMapper (hence the questions) and need to figure some of this out. I haven't quite wrapped my head around the whole ORM thing.

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  • Query on simple C++ threadpool implementation

    - by ticketman
    Stackoverflow has been a tremendous help to me and I'd to give something back to the community. I have been implementing a simple threadpool using the tinythread C++ portable thread library, using what I have learnt from Stackoverflow. I am new to thread programming, so not that comfortable with mutexes, etc. I have a question best asked after presenting the code (which runs quite well under Linux): // ThreadPool.h class ThreadPool { public: ThreadPool(); ~ThreadPool(); // Creates a pool of threads and gets them ready to be used void CreateThreads(int numOfThreads); // Assigns a job to a thread in the pool, but doesn't start the job // Each SubmitJob call will use up one thread of the pool. // This operation can only be undone by calling StartJobs and // then waiting for the jobs to complete. On completion, // new jobs may be submitted. void SubmitJob( void (*workFunc)(void *), void *workData ); // Begins execution of all the jobs in the pool. void StartJobs(); // Waits until all jobs have completed. // The wait will block the caller. // On completion, new jobs may be submitted. void WaitForJobsToComplete(); private: enum typeOfWorkEnum { e_work, e_quit }; class ThreadData { public: bool ready; // thread has been created and is ready for work bool haveWorkToDo; typeOfWorkEnum typeOfWork; // Pointer to the work function each thread has to call. void (*workFunc)(void *); // Pointer to work data void *workData; ThreadData() : ready(false), haveWorkToDo(false) { }; }; struct ThreadArgStruct { ThreadPool *threadPoolInstance; int threadId; }; // Data for each thread ThreadData *m_ThreadData; ThreadPool(ThreadPool const&); // copy ctor hidden ThreadPool& operator=(ThreadPool const&); // assign op. hidden // Static function that provides the function pointer that a thread can call // By including the ThreadPool instance in the void * parameter, // we can use it to access other data and methods in the ThreadPool instance. static void ThreadFuncWrapper(void *arg) { ThreadArgStruct *threadArg = static_cast<ThreadArgStruct *>(arg); threadArg->threadPoolInstance->ThreadFunc(threadArg->threadId); } // The function each thread calls void ThreadFunc( int threadId ); // Called by the thread pool destructor void DestroyThreadPool(); // Total number of threads available // (fixed on creation of thread pool) int m_numOfThreads; int m_NumOfThreadsDoingWork; int m_NumOfThreadsGivenJobs; // List of threads std::vector<tthread::thread *> m_ThreadList; // Condition variable to signal each thread has been created and executing tthread::mutex m_ThreadReady_mutex; tthread::condition_variable m_ThreadReady_condvar; // Condition variable to signal each thread to start work tthread::mutex m_WorkToDo_mutex; tthread::condition_variable m_WorkToDo_condvar; // Condition variable to signal the main thread that // all threads in the pool have completed their work tthread::mutex m_WorkCompleted_mutex; tthread::condition_variable m_WorkCompleted_condvar; }; cpp file: // // ThreadPool.cpp // #include "ThreadPool.h" // This is the thread function for each thread. // All threads remain in this function until // they are asked to quit, which only happens // when terminating the thread pool. void ThreadPool::ThreadFunc( int threadId ) { ThreadData *myThreadData = &m_ThreadData[threadId]; std::cout << "Hello world: Thread " << threadId << std::endl; // Signal that this thread is ready m_ThreadReady_mutex.lock(); myThreadData->ready = true; m_ThreadReady_condvar.notify_one(); // notify the main thread m_ThreadReady_mutex.unlock(); while(true) { //tthread::lock_guard<tthread::mutex> guard(m); m_WorkToDo_mutex.lock(); while(!myThreadData->haveWorkToDo) // check for work to do m_WorkToDo_condvar.wait(m_WorkToDo_mutex); // if no work, wait here myThreadData->haveWorkToDo = false; // need to do this before unlocking the mutex m_WorkToDo_mutex.unlock(); // Do the work switch(myThreadData->typeOfWork) { case e_work: std::cout << "Thread " << threadId << ": Woken with work to do\n"; // Do work myThreadData->workFunc(myThreadData->workData); std::cout << "#Thread " << threadId << ": Work is completed\n"; break; case e_quit: std::cout << "Thread " << threadId << ": Asked to quit\n"; return; // ends the thread } // Now to signal the main thread that my work is completed m_WorkCompleted_mutex.lock(); m_NumOfThreadsDoingWork--; // Unsure if this 'if' would make the program more efficient // if(NumOfThreadsDoingWork == 0) m_WorkCompleted_condvar.notify_one(); // notify the main thread m_WorkCompleted_mutex.unlock(); } } ThreadPool::ThreadPool() { m_numOfThreads = 0; m_NumOfThreadsDoingWork = 0; m_NumOfThreadsGivenJobs = 0; } ThreadPool::~ThreadPool() { if(m_numOfThreads) { DestroyThreadPool(); delete [] m_ThreadData; } } void ThreadPool::CreateThreads(int numOfThreads) { // Check a thread pool has already been created if(m_numOfThreads > 0) return; m_NumOfThreadsGivenJobs = 0; m_NumOfThreadsDoingWork = 0; m_numOfThreads = numOfThreads; m_ThreadData = new ThreadData[m_numOfThreads]; ThreadArgStruct threadArg; for(int i=0; i<m_numOfThreads; ++i) { threadArg.threadId = i; threadArg.threadPoolInstance = this; // Creates the thread and save in a list so we can destroy it later m_ThreadList.push_back( new tthread::thread( ThreadFuncWrapper, (void *)&threadArg ) ); // It takes a little time for a thread to get established. // Best wait until it gets established before creating the next thread. m_ThreadReady_mutex.lock(); while(!m_ThreadData[i].ready) // Check if thread is ready m_ThreadReady_condvar.wait(m_ThreadReady_mutex); // If not, wait here m_ThreadReady_mutex.unlock(); } } // Adds a job to the batch, but doesn't start the job void ThreadPool::SubmitJob(void (*workFunc)(void *), void *workData) { // Check that the thread pool has been created if(!m_numOfThreads) return; if(m_NumOfThreadsGivenJobs >= m_numOfThreads) return; m_ThreadData[m_NumOfThreadsGivenJobs].workFunc = workFunc; m_ThreadData[m_NumOfThreadsGivenJobs].workData = workData; std::cout << "Submitted job " << m_NumOfThreadsGivenJobs << std::endl; m_NumOfThreadsGivenJobs++; } void ThreadPool::StartJobs() { // Check that the thread pool has been created // and some jobs have been assigned if(!m_numOfThreads || !m_NumOfThreadsGivenJobs) return; // Set 'haveworkToDo' flag for all threads m_WorkToDo_mutex.lock(); for(int i=0; i<m_NumOfThreadsGivenJobs; ++i) m_ThreadData[i].haveWorkToDo = true; m_NumOfThreadsDoingWork = m_NumOfThreadsGivenJobs; // Reset this counter so we can resubmit jobs later m_NumOfThreadsGivenJobs = 0; // Notify all threads they have work to do m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); } void ThreadPool::WaitForJobsToComplete() { // Check that a thread pool has been created if(!m_numOfThreads) return; m_WorkCompleted_mutex.lock(); while(m_NumOfThreadsDoingWork > 0) // Check if all threads have completed their work m_WorkCompleted_condvar.wait(m_WorkCompleted_mutex); // If not, wait here m_WorkCompleted_mutex.unlock(); } void ThreadPool::DestroyThreadPool() { std::cout << "Ask threads to quit\n"; m_WorkToDo_mutex.lock(); for(int i=0; i<m_numOfThreads; ++i) { m_ThreadData[i].haveWorkToDo = true; m_ThreadData[i].typeOfWork = e_quit; } m_WorkToDo_condvar.notify_all(); m_WorkToDo_mutex.unlock(); // As each thread terminates, catch them here for(int i=0; i<m_numOfThreads; ++i) { tthread::thread *t = m_ThreadList[i]; // Wait for thread to complete t->join(); } m_numOfThreads = 0; } Example of usage: (this calculates pi-squared/6) struct CalculationDataStruct { int inputVal; double outputVal; }; void LongCalculation( void *theSums ) { CalculationDataStruct *sums = (CalculationDataStruct *)theSums; int terms = sums->inputVal; double sum; for(int i=1; i<terms; i++) sum += 1.0/( double(i)*double(i) ); sums->outputVal = sum; } int main(int argc, char** argv) { int numThreads = 10; // Create pool ThreadPool threadPool; threadPool.CreateThreads(numThreads); // Create thread workspace CalculationDataStruct sums[numThreads]; // Set up jobs for(int i=0; i<numThreads; i++) { sums[i].inputVal = 3000*(i+1); threadPool.SubmitJob(LongCalculation, &sums[i]); } // Run the jobs threadPool.StartJobs(); threadPool.WaitForJobsToComplete(); // Print results for(int i=0; i<numThreads; i++) std::cout << "Sum of " << sums[i].inputVal << " terms is " << sums[i].outputVal << std::endl; return 0; } Question: In the ThreadPool::ThreadFunc method, would better performance be obtained if the following if statement if(NumOfThreadsDoingWork == 0) was included? Also, I'd be grateful of criticisms and ways to improve the code. At the same time, I hope the code is of use to others.

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