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  • Using a Javascript Variable & Sending to JSON

    - by D Franks
    Hello all! I'm trying to take a URL's hash value, send it through a function, turn that value into an object, but ultimately send the value to JSON. I have the following setup: function content(cur){ var mycur = $H(cur); var pars = "p="+mycur.toJSON(); new Ajax.Updater('my_box', 'test.php', { parameters: pars }); } function update(){ if(window.location.hash.length > 0){ content(window.location.hash.substr(1)); // Everything after the '#' } } var curHashVal = window.location.hash; window.onload = function(){ setInterval(function(){ if(curHashVal != window.location.hash){ update(); curHashVal = window.location.hash; } },1); } But for some reason, I can't seem to get the right JSON output. It will either return as a very large object (1:"{",2:"k") or not return at all. I doubt that it is impossible to accomplish, but I've exhausted most of the ways I can think of. Other ways I've tried were "{" + cur + "}" as well as cur.toObject(), however, none seemed to get the job done. Thanks for the help!

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  • Pattern for limiting number of simultaneous asynchronous calls

    - by hitch
    I need to retrieve multiple objects from an external system. The external system supports multiple simultaneous requests (i.e. threads), but it is possible to flood the external system - therefore I want to be able to retrieve multiple objects asynchronously, but I want to be able to throttle the number of simultaneous async requests. i.e. I need to retrieve 100 items, but don't want to be retrieving more than 25 of them at once. When each request of the 25 completes, I want to trigger another retrieval, and once they are all complete I want to return all of the results in the order they were requested (i.e. there is no point returning the results until the entire call is returned). Are there any recommended patterns for this sort of thing? Would something like this be appropriate (pseudocode, obviously)? private List<externalSystemObjects> returnedObjects = new List<externalSystemObjects>; public List<externalSystemObjects> GetObjects(List<string> ids) { int callCount = 0; int maxCallCount = 25; WaitHandle[] handles; foreach(id in itemIds to get) { if(callCount < maxCallCount) { WaitHandle handle = executeCall(id, callback); addWaitHandleToWaitArray(handle) } else { int returnedCallId = WaitHandle.WaitAny(handles); removeReturnedCallFromWaitHandles(handles); } } WaitHandle.WaitAll(handles); return returnedObjects; } public void callback(object result) { returnedObjects.Add(result); }

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  • Rebol Multitasking with Async: why do I get Invalid port spec

    - by Rebol Tutorial
    I tried http://www.mail-archive.com/[email protected]/msg19437.html (I just changed to www.reboltutorial.com) : do http://www.rebol.it/giesse/async-protocol.r handler: func [port [port!] state [word! error!] /local tmp cmd] [ if error? :state [print mold disarm state return true] switch state [ connect [ ; do HTTP request insert port {GET /files/2009/10/word.png HTTP/1.0^M^JHost: www.reboltutorial.com^M^J^M^J} false ] read [false] write [false] close [ ; get data data: copy port close port ;print copy/part data find data "^M^J^M^J" data: to binary! find/tail data "^M^J^M^J" other/image: attempt [load data] other/text: "" show other false ] ] ] port: open async://www.reboltutorial.com:80 port/awake: :handler view layout [ across me: box 100x100 random 255.255.255 0:00:00.5 feel [ engage: func [f a e] [ if a = 'time [ me/color: random 255.255.255 show me ] ] ] other: box 100x100 255.255.255 "Downloading image..." Return Area 208x100 "You can type here while downloading." ] ] But I'm getting this error: >> port: open async://reboltutorial.com:80 ** Access Error: Invalid port spec: async://reboltutorial.com:80 ** Near: port: open async://reboltutorial.com:80 >> port/awake: :handler ** Script Error: port has no value ** Near: port/awake: :handler

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  • FormMethod.Get and query string parameters

    - by parminder
    Hi Experts, I am working on a website in asp.net mvc. I have to show a view where user put some search values like tags and titles to search. I want to use the same Index method for that. I have make my form to use formMethod.Get to send the parameters as querystring. so here is the method [HttpGet] public ActionResult Index(string title, string tags, int? page) { if (string.IsNullOrEmpty(title) return View(null); var list = GetSomeData(); return View(list); } here is my view <div id="searchBox"> <% using (Html.BeginForm(null, null, FormMethod.Get)) { %> <table> <tr> <td> <input type="hidden" id="isPosted" name="isPosted" value="1" /> I am looking for <%=Html.TextBox("Title")%> Tags: <%=Html.TextBox("Tags")%> <input id="search" type="submit" value="Search" /> </td> </tr> </table> <% } %> So when the user first visit the page, he will see only two text boxs and a button. but when he types something in the title and tags and click the search button i will load the view with some data. Now the problem is when i type something in title and tags box and click search, they are received in the method, but are not visible in the url. Is there anything i m doing wrong. help will be appreciated. Regards Parminder

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  • Changing the color of dot depending from value on Morris js graph

    - by Michal Lipa
    Im rendering graph by morris js. Im using data from mysql database by JSON. Everything works fine, but I would like to add one more feature to the graph. (change dot color if there is something in buy action). My JSON: [{"longdate":"2014-08-20 18:20:01","price":"1620","action":"buy"},{"longdate":"2014-08-20 18:40:01","price":"1640","action":""},{"longdate":"2014-08-20 19:00:01","price":"1620","action":""}] So I would like to change dot color for values with buy action. My code for graph: $.getJSON('results.json', function(day_data) { Morris.Line({ element: 'graph', data: day_data, xkey: 'longdate', ykeys: ['price'], labels: ['Cena'], lineColors: lineColor, pointSize: 0, hoverCallback: function(index, options, content) { var date = "<b><font color='black'>Data: "+day_data[index]['longdate']+"</font></b><br>"; var param1 = "<font color='"+lineColor[0]+"'>Cena - "+day_data[index]['price']+"</font><br>"; return date+param1; }, xLabelFormat : function (x) { return changeDateFormat(x); } /*My TRIAL if(action == 'buy'){ pointSize: 4, lineColors: green, } */ }); }); So my code doesnt work, how can I make this working?

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  • .NET out of memory troubleshooting

    - by bushman
    After reading a few enlightening articles about memory in the .NET technology, Out of Memory does not refer to physical memory, 597499. I thought I understood why a C# app would throw an out of memory exception -- until I started experimenting with two servers-- both are having 2.5 gigs of ram, windows server 2003 and identical programs running. The only significant difference between the two being one has 7% hard drive storage left and the other more than 50%. The server with 7% storage space left is consistently throwing an out of memory while the other is performing consistently well. My app is a C# web application that process' hundreds of MBs of String object. Why would this difference happen seeing that the most likely reason for the out of memory issue is out of contiguous virtual address space -- What solutions do you guys propose -- and what do you say about the following 1. turn on the 3gb switch to increase the virtual address space -- 2. instead of using one giant string object, break it up into smaller pieces and collect it in a jagged array (here I have to find a way to return to the caller in some other way as right now, the return type is a string) thanks SO

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  • Problem with python urllib

    - by mudder
    I'm getting an error when ever I try to pull down a web page with urllib.urlopen. I've disabled windows firewall and my AV so its not that. I can access the pages in my browser. I even reinstalled python to rule out it being a broken urllib. Any help would be greatly appreciated. >>> import urllib >>> h = urllib.urlopen("http://www.google.com").read() Traceback (most recent call last): File "<pyshell#1>", line 1, in <module> h = urllib.urlopen("http://www.google.com").read() File "C:\Python26\lib\urllib.py", line 86, in urlopen return opener.open(url) File "C:\Python26\lib\urllib.py", line 205, in open return getattr(self, name)(url) File "C:\Python26\lib\urllib.py", line 344, in open_http h.endheaders() File "C:\Python26\lib\httplib.py", line 904, in endheaders self._send_output() File "C:\Python26\lib\httplib.py", line 776, in _send_output self.send(msg) File "C:\Python26\lib\httplib.py", line 735, in send self.connect() File "C:\Python26\lib\httplib.py", line 716, in connect self.timeout) File "C:\Python26\lib\socket.py", line 514, in create_connection raise error, msg IOError: [Errno socket error] [Errno 10061] No connection could be made because the target machine actively refused it >>>

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  • Literal ampersands in System.Uri query string

    - by Nathan Baulch
    I'm working on a client app that uses a restful service to look up companies by name. It's important that I'm able to include literal ampersands in my queries since this character is quite common in company names. However whenever I pass %26 (the URI escaped ampersand character) to System.Uri, it converts it back to a regular ampersand character! On closer inspection, the only two characters that aren't converted back are hash (%23) and percent (%25). Lets say I want to search for a company named "Pierce & Pierce": var endPoint = "http://localhost/companies?where=Name eq '{0}'"; var name = "Pierce & Pierce"; Console.WriteLine(new Uri(string.Format(endPoint, name))); Console.WriteLine(new Uri(string.Format(endPoint, Uri.EscapeUriString(name)))); Console.WriteLine(new Uri(string.Format(endPoint, Uri.EscapeDataString(name)))); All three of the above combinations return: http://localhost/companies?where=Name eq 'Pierce & Pierce' This causes errors on the server side since the ampersand is (correctly) interpreted as a query arg delimiter. What I really need it to return is the original string: http://localhost/companies?where=Name eq 'Pierce %26 Pierce' How can I work around this behavior without discarding System.Uri entirely? I can't replace all ampersands with %26 at the last moment because there will usually be multiple query args involved and I don't want to destroy their delimiters. Note: A similar problem was discussed in this question but I'm specifically referring to System.Uri.

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  • Iterate through main function in C?

    - by Mohit Deshpande
    Here is my main function: int main(int argc, char **argv) { LoadFile(); Node *temp; char *key; switch (GetUserInput()) { case 1: temp = malloc(sizeof(Node)); printf("\nEnter the key of the new node: "); scanf("%s", temp->key); printf("\nEnter the value of the new node: "); scanf("%s", temp->value); AddNode(temp); free(temp); break; case 2: key = malloc(sizeof(char *)); printf("Enter the key of the node you want to delete: "); scanf("%s", key); DeleteNode(key); free(key); break; case 3: PrintAll(); break; case 4: SaveFile(); break; case 5: return 0; break; default: printf("\nWrong choice!\n"); break; } return 0; } The only problem with it is that after any case statement breaks, the program just exits out. I understand why, but I don't know how to fix it. I want the program to repeat itself each time even after the case statements. Would I just say: main(argc, argv); before every break statement?

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  • Handling Errors in PHP

    - by Mike
    I have a custom class that, when called, will redirect to a page and send a 'message_type' and 'message' variable via GET. When the page opens it checks for these variables and displays a 'success', 'warning', or 'error' message depending on the 'message_type' variable. I made it so the user thinks they stay on the same page. It also allows for other variables to be passed along with the message. Is this good practice, or should I just start using exceptions? Example: //Call a static function that will redirect to a page, with an error message RedirectWithMessage::go('somepage.php', MessageType::ERROR, 'Error message here.'); The following checkMessage() function is an include file: function checkMessage() { if((isset($_GET['message_type']) && strlen($_GET['message_type'])) && (isset($_GET['message']) && strlen($_GET['message_type']))) { DisplayMessage::display($_GET['message_type'], $_GET['message']); return true; } return false; } On the page that is redirected to, call checkMessage(); //If a message is received, display it. If not, do nothing checkMessage(); I know this might be vague, and I can supply more code if necessary. I guess the issue is that I don't have much experience using exceptions, but I think they seem cumbersome (writing try-catch blocks everywhere). Please let me know if I am making this more difficult for myself or if there is a better solution. Thanks! Mike

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  • Context Menu on QGraphicsWidget

    - by onurozcelik
    Hi, In my application I have two object type. One is field item, other is composite item. Composite items may contain two or more field items. Here is my composite item implementation. #include "compositeitem.h" CompositeItem::CompositeItem(QString id,QList<FieldItem *> _children) { children = _children; } CompositeItem::~CompositeItem() { } QRectF CompositeItem::boundingRect() const { //Not carefully thinked about it return QRectF(QPointF(-50,-150),QSizeF(250,250)); } void CompositeItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget ) { FieldItem *child; foreach(child,children) { child->paint(painter,option,widget); } } QSizeF CompositeItem::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const { QSizeF itsSize(0,0); FieldItem *child; foreach(child,children) { // if its size empty set first child size to itsSize if(itsSize.isEmpty()) itsSize = child->sizeHint(Qt::PreferredSize); else { QSizeF childSize = child->sizeHint(Qt::PreferredSize); if(itsSize.width() < childSize.width()) itsSize.setWidth(childSize.width()); itsSize.setHeight(itsSize.height() + childSize.height()); } } return itsSize; } void CompositeItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event) { qDebug()<<"Test"; } My first question is how I can propagate context menu event to specific child. Picture on the above demonstrates one of my possible composite item. If you look on the code above you will see that I print "Test" when context menu event occurs. When I right click on the line symbol I see that "Test" message is printed. But when I right click on the signal symbol "Test" is not printed and I want it to be printed. My second question what cause this behaviour. How do I overcome this.

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  • MonoRail ActiveRecord - The UPDATE statement conflicted with the FOREIGN KEY SAME TABLE

    - by Justin
    Hey all, I'm new to MonoRail and ActiveRecord and have inherited an application that I need to modify. I have a Category table (Id, Name) and I'm adding a ParentId FK which references the Id in the same table so that you can have parent/child category relationships. I tried adding this to my Category model class: [Property] public int ParentId { get; set; } I also tried doing it this way: [BelongsTo("ParentId")] public Category Parent { get; set; } When I call a method to get all parent categories (they have a null ParentId), it works fine: public static Category[] GetParentCategories() { var criteria = DetachedCriteria.For<Core.Models.Category>(); return (FindAllByProperty("ParentId", null)); } However, when I call a method to get all child categories within a specific category, it errors out: public static Category[] GetChildCategories(int parentId) { var criteria = DetachedCriteria.For<Core.Models.Category>(); return (FindAllByProperty("ParentId", parentId)); } The error is: "The UPDATE statement conflicted with the FOREIGN KEY SAME TABLE constraint \"FK_Category_ParentId\". The conflict occurred in database \"UCampus\", table \"dbo.Category\", column 'Id'.\r\nThe statement has been terminated." I'm hard-coding in the parentId parameter as 1 and I'm 100% sure it exists as an id in the Category table so I don't know why it'd give this error. Also, I'm doing a select, not an update, so what is going on here?? Thanks for any input on this, Justin

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  • How can I work around SQL Server - Inline Table Value Function execution plan variation based on par

    - by Ovidiu Pacurar
    Here is the situation: I have a table value function with a datetime parameter ,lest's say tdf(p_date) , that filters about two million rows selecting those with column date smaller than p_date and computes some aggregate values on other columns. It works great but if p_date is a custom scalar value function (returning the end of day in my case) the execution plan is altered an the query goes from 1 sec to 1 minute execution time. A proof of concept table - 1K products, 2M rows: CREATE TABLE [dbo].[POC]( [Date] [datetime] NOT NULL, [idProduct] [int] NOT NULL, [Quantity] [int] NOT NULL ) ON [PRIMARY] The inline table value function: CREATE FUNCTION tdf (@p_date datetime) RETURNS TABLE AS RETURN ( SELECT idProduct, SUM(Quantity) AS TotalQuantity, max(Date) as LastDate FROM POC WHERE (Date < @p_date) GROUP BY idProduct ) The scalar value function: CREATE FUNCTION [dbo].[EndOfDay] (@date datetime) RETURNS datetime AS BEGIN DECLARE @res datetime SET @res=dateadd(second, -1, dateadd(day, 1, dateadd(ms, -datepart(ms, @date), dateadd(ss, -datepart(ss, @date), dateadd(mi,- datepart(mi,@date), dateadd(hh, -datepart(hh, @date), @date)))))) RETURN @res END Query 1 - Working great SELECT * FROM [dbo].[tdf] (getdate()) The end of execution plan: Stream Aggregate Cost 13% <--- Clustered Index Scan Cost 86% Query 2 - Not so great SELECT * FROM [dbo].[tdf] (dbo.EndOfDay(getdate())) The end of execution plan: Stream Aggregate Cost 4% <--- Filter Cost 12% <--- Clustered Index Scan Cost 86%

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  • How can I read the properties of an object that I assign to the Session in ASP.NET MVC?

    - by quakkels
    Hey all, I'm trying my hand at creating a session which stores member information which the application can use to reveal certain navigation and allow access to certain pages and member role specific functionality. I've been able to assign my MemberLoggedIn object to the session in this way: //code excerpt start... MemberLoggedIn loggedIn = new MemberLoggedIn(); if (computedHash == member.Hash) { loggedIn.ID = member.ID; loggedIn.Username = member.Username; loggedIn.Email = member.Email; loggedIn.Superuser = member.Superuser; loggedIn.Active = member.Active; Session["loggedIn"] = loggedIn; } else if (ModelState.IsValid) { ModelState.AddModelError("Password", "Incorrect Username or Password."); } return View(); That works great. I then can send the properties of Session["loggedIn"] to the View in this way: [ChildActionOnly] public ActionResult Login() { if (Session["loggedIn"] != null) ViewData.Model = Session["loggedIn"]; else ViewData.Model = null; return PartialView(); } In the Partial View I can reference the session data by using Model.Username or Model.Superuser. However, it doesn't seem to work that way in the controller or in a custom Action Filter. Is there a way to get the equivalent of Session["loggedIn"].Username?

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  • reading csv files in scipy/numpy in Python

    - by user248237
    I am having trouble reading a csv file, delimited by tabs, in python. I use the following function: def csv2array(filename, skiprows=0, delimiter='\t', raw_header=False, missing=None, with_header=True): """ Parse a file name into an array. Return the array and additional header lines. By default, parse the header lines into dictionaries, assuming the parameters are numeric, using 'parse_header'. """ f = open(filename, 'r') skipped_rows = [] for n in range(skiprows): header_line = f.readline().strip() if raw_header: skipped_rows.append(header_line) else: skipped_rows.append(parse_header(header_line)) f.close() if missing: data = genfromtxt(filename, dtype=None, names=with_header, deletechars='', skiprows=skiprows, missing=missing) else: if delimiter != '\t': data = genfromtxt(filename, dtype=None, names=with_header, delimiter=delimiter, deletechars='', skiprows=skiprows) else: data = genfromtxt(filename, dtype=None, names=with_header, deletechars='', skiprows=skiprows) if data.ndim == 0: data = array([data.item()]) return (data, skipped_rows) the problem is that genfromtxt complains about my files, e.g. with the error: Line #27100 (got 12 columns instead of 16) I am not sure where these errors come from. Any ideas? Here's an example file that causes the problem: #Gene 120-1 120-3 120-4 30-1 30-3 30-4 C-1 C-2 C-5 genesymbol genedesc ENSMUSG00000000001 7.32 9.5 7.76 7.24 11.35 8.83 6.67 11.35 7.12 Gnai3 guanine nucleotide binding protein alpha ENSMUSG00000000003 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Pbsn probasin Is there a better way to write a generic csv2array function? thanks.

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  • Binding ListBox ItemCount to IvalueConverter

    - by Ben
    Hi All, I am fairly new to WPF so forgive me if I am missing something obvious. I'm having a problem where I have a collection of AggregatedLabels and I am trying to bind the ItemCount of each AggregatedLabel to the FontSize in my DataTemplate so that if the ItemCount of an AggregatedLabel is large then a larger fontSize will be displayed in my listBox etc. The part that I am struggling with is the binding to the ValueConverter. Can anyone assist? Many thanks! XAML Snippet <DataTemplate x:Key="TagsTemplate"> <WrapPanel> <TextBlock Text="{Binding Name, Mode=Default}" TextWrapping="Wrap" FontSize="{Binding ItemCount, Converter={StaticResource CountToFontSizeConverter}, Mode=Default}" Foreground="#FF0D0AF7"/> </WrapPanel> </DataTemplate> <ListBox x:Name="tagsList" ItemsSource="{Binding AggregatedLabels, Mode=Default}" ItemTemplate="{StaticResource TagsTemplate}" Style="{StaticResource tagsStyle}" Margin="200,10,16.171,11.88" /> AggregatedLabel Collection using (DB2DataReader dr = command.ExecuteReader()) { while (dr.Read()) { AggregatedLabelModel aggLabel = new AggregatedLabelModel(); aggLabel.ID = Convert.ToInt32(dr["LABEL_ID"]); aggLabel.Name = dr["LABEL_NAME"].ToString(); LabelData.Add(aggLabel); } } Converter public class CountToFontSizeConverter : IValueConverter { #region IValueConverter Members public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { const int minFontSize = 6; const int maxFontSize = 38; const int increment = 3; int count = (int)value; if ((minFontSize + count + increment) < maxFontSize) { return minFontSize + count + increment; } return maxFontSize; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new NotImplementedException(); } #endregion } AggregatedLabel Class public class AggregatedLabelModel { public int ID { get; set; } public string Name { get; set; } } CollectionView ListCollectionView labelsView = new ListCollectionView(LabelData); labelsView.GroupDescriptions.Add(new PropertyGroupDescription("Name"));

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  • Render multiple control collections in ASP.NET custom control

    - by Monty
    I've build a custom WebControl, which has the following structure: <gws:ModalBox ID="ModalBox1" HeaderText="Title" runat="server"> <Contents>(controls...)</Contents> <Footer>(controls...)</Footer> </gws:ModalBox> The control contains two ControlCollection properties, 'Contents' and 'Footer'. Never tried to build a control with multiple control collections, but solved it like this (simplified): [PersistChildren(false), ParseChildren(true)] public class ModalBox : WebControl { private ControlCollection _contents; private ControlCollection _footer; public ModalBox() : base() { this._contents = base.CreateControlCollection(); this._footer = base.CreateControlCollection(); } [PersistenceMode(PersistenceMode.InnerProperty)] public ControlCollection Contents { get { return this._contents; } } [PersistenceMode(PersistenceMode.InnerProperty)] public ControlCollection Footer { get { return this._footer; } } protected override void RenderContents(HtmlTextWriter output) { // Render content controls. foreach (Control control in this.Contents) { control.RenderControl(output); } // Render footer controls. foreach (Control control in this.Footer) { control.RenderControl(output); } } } However it seems to render properly, it doesn't work anymore if I add some asp.net labels and input controls inside the property. I'll get the HttpException: Unable to find control with id 'KeywordTextBox' that is associated with the Label 'KeywordLabel'. Somewhat understandable, because the label appears before the textbox in the controlcollection. However, with default asp.net controls it does work, so why doesn't this work? What am I doing wrong? Is it even possible to have two control collections in one control? Should I render it differently? Thanks for replies.

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  • SQL Concurrent test update question

    - by ptoinson
    Howdy Folks, I have a SQLServer 2008 database in which I have a table for Tags. A tag is just an id and a name. The definition of the tags table looks like: CREATE TABLE [dbo].[Tag]( [ID] [int] IDENTITY(1,1) NOT NULL, [Name] [varchar](255) NOT NULL CONSTRAINT [PK_Tag] PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ) Name is also a unique index. further I have several processes adding data to this table at a pretty rapid rate. These processes use a stored proc that looks like: ALTER PROC [dbo].[lg_Tag_Insert] @Name varchar(255) AS DECLARE @ID int SET @ID = (select ID from Tag where Name=@Name ) if @ID is null begin INSERT Tag(Name) VALUES (@Name) RETURN SCOPE_IDENTITY() end else begin return @ID end My issues is that, other than being a novice at concurrent database design, there seems to be a race condition that is causing me to occasionally get an error that I'm trying to enter duplicate keys (Name) into the DB. The error is: Cannot insert duplicate key row in object 'dbo.Tag' with unique index 'IX_Tag_Name'. This makes sense, I'm just not sure how to fix this. If it where code I would know how to lock the right areas. SQLServer is quite a different beast. First question is what is the proper way to code this 'check, then update pattern'? It seems I need to get an exclusive lock on the row during the check, rather than a shared lock, but it's not clear to me the best way to do that. Any help in the right direction will be greatly appreciated. Thanks in advance.

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  • How is conversion of float/double to int handled in printf?

    - by Sandip
    Consider this program int main() { float f = 11.22; double d = 44.55; int i,j; i = f; //cast float to int j = d; //cast double to int printf("i = %d, j = %d, f = %d, d = %d", i,j,f,d); //This prints the following: // i = 11, j = 44, f = -536870912, d = 1076261027 return 0; } Can someone explain why the casting from double/float to int works correctly in the first case, and does not work when done in printf? This program was compiled on gcc-4.1.2 on 32-bit linux machine. EDIT: Zach's answer seems logical, i.e. use of format specifiers to figure out what to pop off the stack. However then consider this follow up question: int main() { char c = 'd'; // sizeof c is 1, however sizeof character literal // 'd' is equal to sizeof(int) in ANSI C printf("lit = %c, lit = %d , c = %c, c = %d", 'd', 'd', c, c); //this prints: lit = d, lit = 100 , c = d, c = 100 //how does printf here pop off the right number of bytes even when //the size represented by format specifiers doesn't actually match //the size of the passed arguments(char(1 byte) & char_literal(4 bytes)) return 0; } How does this work?

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  • A linked list with multiple heads in Java

    - by Emile
    Hi, I have a list in which I'd like to keep several head pointers. I've tried to create multiple ListIterators on the same list but this forbid me to add new elements in my list... (see Concurrent Modification exception). I could create my own class but I'd rather use a built-in implementation ;) To be more specific, here is an inefficient implementation of two basic operations and the one wich doesn't work : class MyList <E { private int[] _heads; private List<E _l; public MyList ( int nbHeads ) { _heads = new int[nbHeads]; _l = new LinkedList<E(); } public void add ( E e ) { _l.add(e); } public E next ( int head ) { return _l.get(_heads[head++]); // ugly } } class MyList <E { private Vector<ListIterator<E _iters; private List<E _l; public MyList ( int nbHeads ) { _iters = new Vector<ListIterator<E(nbHeads); _l = new LinkedList<E(); for( ListIterator<E iter : _iters ) iter = _l.listIterator(); } public void add ( E e ) { _l.add(e); } public E next ( int head ) { // ConcurrentModificationException because of the add() return _iters.get(head).next(); } } Emile

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  • Ruby on Rails script/console printing more than expected

    - by Lloyd
    I have a simple model setup in my Ruby on Rails app. (User {name, username, lat, lon}) and am writing a basic extension to the model. I would like the method to return users within a certain distance. It all works just fine in the page view, but as I am debugging I would like to work through some testing using the script/console. My question: It seems to be printing to the screen the entire result set when I run it from the command line and script/console. My model: class User < ActiveRecord::Base def distance_from(aLat, aLon) Math.sqrt((69.1*(aLat - self.lat))**2 + (49*(aLon - self.lon))**2 ) end def distance_from_user(aUser) distance_from(aUser.lat, aUser.lon) end def users_within(distance) close_users = [] users = User.find(:all) users.each do |u| close_users << u if u.distance_from_user(self) < distance end return close_users end end and from the command line I am running >> u = User.find_by_username("someuser") >> print u.users_within(1) So, I guess I would like to know why it's printing the whole result set, and if there is a way to suppress it so as to only print what I want?

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  • javascript setTimeout function out of scope.

    - by Keyo
    I am trying to call showUpload(); from within two setTimeouts. Neither works. It seems to be out of scope and I'm not sure why. I tried this.showUpload() which didn't work either. $(document).ready(function(){ var progress_key = $('#progress_key').val(); // this sets up the progress bar $('#uploadform').submit(function() { setTimeout("showUpload()",1500); $("#progressbar").progressbar({ value:0}).fadeIn(); }); // uses ajax to poll the uploadprogress.php page with the id // deserializes the json string, and computes the percentage (integer) // update the jQuery progress bar // sets a timer for the next poll in 750ms function showUpload() { $.get("/myid/videos/uploadprogress/" + progress_key, function(data) { if (!data) return; var response; eval ("response = " + data); if (!response) return; var percentage = Math.floor(100 * parseInt(response['bytes_uploaded']) / parseInt(response['bytes_total'])); $("#progressbar").progressbar({ value:percentage}) }); setTimeout("showUpload()", 750); } }); Thank you for your time.

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  • C# Compress Triple Byte Array

    - by Mark
    Hi. I currently got this script, which compresses byte arrays. But I need it rewritten, so it can compress triple byte arrays [,,] Thanks! public static byte[] Compress(byte[] buffer) { MemoryStream ms = new MemoryStream(); GZipStream zip = new GZipStream(ms, CompressionMode.Compress, true); zip.Write(buffer, 0, buffer.Length); zip.Close(); ms.Position = 0; MemoryStream outStream = new MemoryStream(); byte[] compressed = new byte[ms.Length]; ms.Read(compressed, 0, compressed.Length); byte[] gzBuffer = new byte[compressed.Length + 4]; Buffer.BlockCopy(compressed, 0, gzBuffer, 4, compressed.Length); Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gzBuffer, 0, 4); return gzBuffer; } public static byte[] Decompress(byte[] gzBuffer) { MemoryStream ms = new MemoryStream(); int msgLength = BitConverter.ToInt32(gzBuffer, 0); ms.Write(gzBuffer, 4, gzBuffer.Length - 4); byte[] buffer = new byte[msgLength]; ms.Position = 0; GZipStream zip = new GZipStream(ms, CompressionMode.Decompress); zip.Read(buffer, 0, buffer.Length); return buffer; }

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  • boost::lambda bind expressions can't get bind to string's empty() to work

    - by navigator
    Hi, I am trying to get the below code snippet to compile. But it fails with: error C2665: 'boost::lambda::function_adaptor::apply' : none of the 8 overloads could convert all the argument types. Sepcifying the return type when calling bind does not help. Any idea what I am doing wrong? Thanks. #include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> #include <string> #include <map> int main() { namespace bl = boost::lambda; typedef std::map<int, std::string> types; types keys_and_values; keys_and_values[ 0 ] = "zero"; keys_and_values[ 1 ] = "one"; keys_and_values[ 2 ] = "Two"; std::for_each( keys_and_values.begin(), keys_and_values.end(), std::cout << bl::constant("Value empty?: ") << std::boolalpha << bl::bind(&std::string::empty, bl::bind(&types::value_type::second, _1)) << "\n"); return 0; }

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  • Why should the "prime-based" hashcode implmentation be used instead of the "naive" one?

    - by Wilhelm
    I have seen that a prime number implmentation of the GetHashCode function is being recommend, for example here. However using the following code (in VB, sorry), it seems as if that implementation gives the same hash density as a "naive" xor implementation. If the density is the same, I would suppose there is the same probability of cllision in both implementations. Am I missing anything on why is the prime approach preferred? I am supossing that if the hash code is a byte I do not lose generality for the integer case. Sub Main() Dim XorHashes(255) As Integer Dim PrimeHashes(255) As Integer For i = 0 To 255 For j = 0 To 255 For k = 0 To 255 XorHashes(GetXorHash(i, j, k)) += 1 PrimeHashes(GetPrimeHash(i, j, k)) += 1 Next Next Next For i = 0 To 255 Console.WriteLine("{0}: {1}, {2}", i, XorHashes(i), PrimeHashes(i)) Next Console.ReadKey() End Sub Public Function GetXorHash(ByVal valueOne As Integer, ByVal valueTwo As Integer, ByVal valueThree As Integer) As Byte Return CByte((valueOne Xor valueTwo Xor valueThree) Mod 256) End Function Public Function GetPrimeHash(ByVal valueOne As Integer, ByVal valueTwo As Integer, ByVal valueThree As Integer) As Byte Dim TempHash = 17 TempHash = 31 * TempHash + valueOne TempHash = 31 * TempHash + valueTwo TempHash = 31 * TempHash + valueThree Return CByte(TempHash Mod 256) End Function

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