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  • How to benchmark on multi-core processors

    - by Pascal Cuoq
    I am looking for ways to perform micro-benchmarks on multi-core processors. Context: At about the same time desktop processors introduced out-of-order execution that made performance hard to predict, they, perhaps not coincidentally, also introduced special instructions to get very precise timings. Example of these instructions are rdtsc on x86 and rftb on PowerPC. These instructions gave timings that were more precise than could ever be allowed by a system call, allowed programmers to micro-benchmark their hearts out, for better or for worse. On a yet more modern processor with several cores, some of which sleep some of the time, the counters are not synchronized between cores. We are told that rdtsc is no longer safe to use for benchmarking, but I must have been dozing off when we were explained the alternative solutions. Question: Some systems may save and restore the performance counter and provide an API call to read the proper sum. If you know what this call is for any operating system, please let us know in an answer. Some systems may allow to turn off cores, leaving only one running. I know Mac OS X Leopard does when the right Preference Pane is installed from the Developers Tools. Do you think that this make rdtsc safe to use again? More context: Please assume I know what I am doing when trying to do a micro-benchmark. If you are of the opinion that if an optimization's gains cannot be measured by timing the whole application, it's not worth optimizing, I agree with you, but I cannot time the whole application until the alternative data structure is finished, which will take a long time. In fact, if the micro-benchmark were not promising, I could decide to give up on the implementation now; I need figures to provide in a publication whose deadline I have no control over.

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  • Why do bind1st and bind2nd require constant function objects?

    - by rlbond
    So, I was writing a C++ program which would allow me to take control of the entire world. I was all done writing the final translation unit, but I got an error: error C3848: expression having type 'const `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>' would lose some const-volatile qualifiers in order to call 'void `anonymous-namespace'::ElementAccumulator<T,BinaryFunction>::operator ()(const point::Point &,const int &)' with [ T=SideCounter, BinaryFunction=std::plus<int> ] c:\program files (x86)\microsoft visual studio 9.0\vc\include\functional(324) : while compiling class template member function 'void std::binder2nd<_Fn2>::operator ()(point::Point &) const' with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] c:\users\****\documents\visual studio 2008\projects\TAKE_OVER_THE_WORLD\grid_divider.cpp(361) : see reference to class template instantiation 'std::binder2nd<_Fn2>' being compiled with [ _Fn2=`anonymous-namespace'::ElementAccumulator<SideCounter,std::plus<int>> ] I looked in the specifications of binder2nd and there it was: it took a const AdaptibleBinaryFunction. So, not a big deal, I thought. I just used boost::bind instead, right? Wrong! Now my take-over-the-world program takes too long to compile (bind is used inside a template which is instantiated quite a lot)! At this rate, my nemesis is going to take over the world first! I can't let that happen -- he uses Java! So can someone tell me why this design decision was made? It seems like an odd decision. I guess I'll have to make some of the elements of my class mutable for now...

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  • How to interpolate in MatLab

    - by G Sam
    I have a 1x1 Matrix of points which specifies speed of a drive with respect to time. This speed changes throughout the operation; which means that the difference between two points is changing. To give you an example: M = [1; 2; 3; 5; 7; 9; 11; 15; 19]. (Only that this is a 892x1 matrix) I want to make this matrix twice as long (so changing the relative speed per timestep), while retaining the way the speeds change. Eg: M' = [1; 1.5; 2; 2.5; 3; 4; 5; 6; 7; 8; 9; 10; 11; 13; 15; 17; 19]. Is there an easy way to do this in MatLab? So far I have tried upsampling (which fills the time step with zeros); interp (which fills it with low-pass interpolation. Thanks!

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  • C#: Wrong answer when finding "cool" numbers.

    - by user300484
    Hello you all! In my application, a "cool" number is a number that is both a square and a cube, like for example: 64 = 8^2 and 64 = 4^3. My application is supposed to find the number of "cool numbers" between a range given by the user. I wrote my code and the application runs fine, but it is giving me the wrong answer. Can you help me here please? for example: IMPUT 1 100 OUTPUT 1 using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { double a = Convert.ToDouble(Console.ReadLine()); // first number in the range double b = Convert.ToDouble(Console.ReadLine()); // second number in the range long x = 0; for (double i = a; i <= b; i++) { double cube = 1.0 / 3.0; double cuad = 1.0 / 2.0; double crt = Math.Pow(i, cube); // cube root double sqrt = Math.Pow(i, cuad); // square root if ((crt * 10) % 10 == 0 || (sqrt * 10) % 10 == 0) // condition to determine if it is a cool number. x++; } Console.WriteLine(x); Console.ReadLine(); } } }

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  • Adding web reference on client when using Net.TCP

    - by Marko
    Hi everyone... I am trying to using Net.TCP in my WCF Service, which is self hosted, when i try to add this service reference through web reference to my client, i am not able access the classes and methods of that service, can any have any idea to achieve this... How I can add web references in this case. My Service has one method (GetNumber) that returns int. WebService: public class WebService : IWebService { public int GetNumber(int num) { return num + 1; } } Service Contract code: [ServiceContract] public interface IWebService { [OperationContract] int GetNumber(int num); } WCF Service code: ServiceHost host = new ServiceHost(typeof(WebService)); host.AddServiceEndpoint(typeof(IWebService), new NetTcpBinding(), new Uri("net.tcp://" + Dns.GetHostName() + ":1255/WebService")); NetTcpBinding binding = new NetTcpBinding(); binding.TransferMode = TransferMode.Streamed; binding.ReceiveTimeout = TimeSpan.MaxValue; binding.MaxReceivedMessageSize = long.MaxValue; Console.WriteLine("{0}", Dns.GetHostName().ToString()); Console.WriteLine("Opening Web Service..."); host.Open(); Console.WriteLine("Web Service is running on port {0}",1255); Console.WriteLine("Press <ENTER> to EXIT"); Console.ReadLine(); This works fine. Only problem is how to add references of this service in my client application. I just want to send number and to receive an answer. Can anyone help me?

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  • New Rails deployment half working...not sure why?

    - by Meltemi
    I'm in the final stages of going round trip through the entire Rails cycle: development - test - production (on an external server). I'm very close...but seeing some errors with the production version and don't know enough about Rails' "magic" to troubleshoot it yet... all seems well and I can load my app by going to www.mydomain.com/rails and it seems to work...I can interact with my app and create new objects in my database. However, when I go to www.mydomain.com/rails/ (difference is the trailing slash) i get a webpage that just says "Index from public" on it?!? I don't know where that's coming from? index.html is long removed from public. this may or may not be related to why I can't access, say, the first record in one of my classes by calling its controller like so: www.mydomain.com/rails/mycontroller/1 . and yes, there are records in the database. anyway, something's askew. it works fine on development box. but, only half working on production server. anyone know what might be causing this? this app is running on the server box (not development) Installed Passenger on server to serve app via Apache modified my httpd.conf with Passenger's stuff (headache but finally got it to respond) loaded schema into the production database: rake db:schema:load RAILS_ENV=production

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  • Kernighan & Ritchie word count example program in a functional language

    - by Frank
    I have been reading a little bit about functional programming on the web lately and I think I got a basic idea about the concepts behind it. I'm curious how everyday programming problems which involve some kind of state are solved in a pure functional programing language. For example: how would the word count program from the book 'The C programming Language' be implemented in a pure functional language? Any contributions are welcome as long as the solution is in a pure functional style. Here's the word count C code from the book: #include <stdio.h> #define IN 1 /* inside a word */ #define OUT 0 /* outside a word */ /* count lines, words, and characters in input */ main() { int c, nl, nw, nc, state; state = OUT; nl = nw = nc = 0; while ((c = getchar()) != EOF) { ++nc; if (c == '\n') ++nl; if (c == ' ' || c == '\n' || c = '\t') state = OUT; else if (state == OUT) { state = IN; ++nw; } } printf("%d %d %d\n", nl, nw, nc); }

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  • How do I get rid of these warnings?

    - by Brian Postow
    This is really several questions, but anyway... I'm working with a big project in XCode, relatively recently ported from MetroWorks (Yes, really) and there's a bunch of warnings that I want to get rid of. Every so often an IMPORTANT warning comes up, but I never look at them because there's too many garbage ones. So, if I can either figure out how to get XCode to stop giving the warning, or actually fix the problem, that would be great. Here are the warnings: It claims that <map.h> is antiquated. However, when I replace it with <map> my files don't compile. Evidently, there's something in map.h that isn't in map... this decimal constant is unsigned only in ISO C90 This is a large number being compared to an unsigned long. I have even cast it, with no effect. enumeral mismatch in conditional expression: <anonymous enum> vs <anonymous enum> This appears to be from a ?: operator. Possibly that the then and else branches don't evaluate to the same type? Except that in at least one case, it's (matchVp == NULL ? noErr : dupFNErr) And since those are both of type OSErr, which is mac defined... I'm not sure what's up. It also seems to come up when I have other pairs of mac constants... multi-character character constant This one is obvious. The problem is that I actually NEED multi-character constants... -fwritable-strings not compatible with literal CF/NSString I unchecked the "Strings are Read-Only" box in both the project and target settings... and it seems to have had no effect...

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  • Method works on Emulator but no on Microsoft Surface unit?

    - by Roflcoptr
    I have the following code. The StartRecord method trows an error on the Microsoft Surface Unit. But when I'm testing it on the emulator, it all works great. Any hints how 1) to find the exception that is thrown on the Microsoft Surface Unit? 2) to find the error in the code? any assumptions? private void StartRecord(object sender, ContactEventArgs e) { isRecording = true; StartButton.IsEnabled = false; recordTimer = new Timer(10); recordTimer.Elapsed += new ElapsedEventHandler(recordTimer_Elapsed); PlaybackRoot.Visibility = System.Windows.Visibility.Collapsed; EllapsedRecord.Visibility = System.Windows.Visibility.Visible; InputLevel.Visibility = System.Windows.Visibility.Visible; long time = DateTime.Now.Ticks; String fileName = Convert.ToString(time) + ".wav"; Console.WriteLine(fileName); startTime = DateTime.UtcNow; recordTimer.Start(); record = new AudioRecording(fileName); record.getSampleAggregator().MaximumCalculated += new EventHandler<MaxSampleEventArgs>(AudioControl_MaximumCalculated); record.start(); }

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  • Method for defining simultaneous has-many and has-one associations between two models in CakePHP?

    - by Hobonium
    One thing with which I have long had problems, within the CakePHP framework, is defining simultaneous hasOne and hasMany relationships between two models. For example: BlogEntry hasMany Comment BlogEntry hasOne MostRecentComment (where MostRecentComment is the Comment with the most recent created field) Defining these relationships in the BlogEntry model properties is problematic. CakePHP's ORM implements a has-one relationship as an INNER JOIN, so as soon as there is more than one Comment, BlogEntry::find('all') calls return multiple results per BlogEntry. I've worked around these situations in the past in a few ways: Using a model callback (or, sometimes, even in the controller or view!), I've simulated a MostRecentComment with: $this->data['MostRecentComment'] = $this->data['Comment'][0]; This gets ugly fast if, say, I need to order the Comments any way other than by Comment.created. It also doesn't Cake's in-built pagination features to sort by MostRecentComment fields (e.g. sort BlogEntry results reverse-chronologically by MostRecentComment.created. Maintaining an additional foreign key, BlogEntry.most_recent_comment_id. This is annoying to maintain, and breaks Cake's ORM: the implication is BlogEntry belongsTo MostRecentComment. It works, but just looks...wrong. These solutions left much to be desired, so I sat down with this problem the other day, and worked on a better solution. I've posted my eventual solution below, but I'd be thrilled (and maybe just a little mortified) to discover there is some mind-blowingly simple solution that has escaped me this whole time. Or any other solution that meets my criteria: it must be able to sort by MostRecentComment fields at the Model::find level (ie. not just a massage of the results); it shouldn't require additional fields in the comments or blog_entries tables; it should respect the 'spirit' of the CakePHP ORM. (I'm also not sure the title of this question is as concise/informative as it could be.)

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  • Creating a Function in SQL Server with a Phone Number as a parameter and returns a Random Number

    - by Emer
    Hi Guys, I am hoping someone can help me here as google is not being as forthcoming as I would have liked. I am relatively new to SQL Server and so this is the first function I have set myself to do. The outline of the function is that it has a Phone number varchar(15) as a parameter, it checks that this number is a proper number, i.e. it is 8 digits long and contains only numbers. The main character I am trying to avoid is '+'. Good Number = 12345678 Bad Number = +12345678. Once the number is checked I would like to produce a random number for each phone number that is passed in. I have looked at substrings, the like operator, Rand(), left(), Right() in order to search through the number and then produce a random number. I understand that Rand() will produce the same random number unless alterations are done to it but right now it is about actually getting some working code. Any hints on this would be great or even point me towards some more documentation. I have read books online and they haven't helped me, maybe I am not looking in the right places. Here is a snippet of code I was working on the Rand declare @Phone Varchar (15) declare @Counter Varchar (1) declare @NewNumber Varchar(15) set @Phone = '12345678' set @Counter = len(@Phone) while @Counter > 0 begin select case when @Phone like '%[0-9]%' then cast(rand()*100000000 as int) else 'Bad Number' end set @counter = @counter - 1 end return Thanks for the help in advance Emer

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  • LINQ to Sql: Insert instead of Update

    - by Christina Mayers
    I am stuck with this problems for a long time now. Everything I try to do is insert a row in my DB if it's new information - if not update the existing one. I've updated many entities in my life before - but what's wrong with this code is beyond me (probably something pretty basic) I guess I can't see the wood for the trees... private Models.databaseDataContext db = new Models.databaseDataContext(); internal void StoreInformations(IEnumerable<EntityType> iEnumerable) { foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type == null) { db.EntityType.InsertOnSubmit(item); } else { type.Date = item.Date; type.LastUpdate = DateTime.Now(); type.End = item.End; } } } internal void Save() { db.SubmitChanges(); } Edit: just checked the ChangeSet, there are no updates only inserts. For now I've settled with foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type != null) { db.Exams.DeleteOnSubmit(type); } db.EntityType.InsertOnSubmit(item); } but I'd love to do updates and lose these unnecessary delete statements.

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  • What can be the reason for Windows error ERROR_DISK_FULL (112) when opening a NTFS alternate data st

    - by ur
    My application writes some bytes of data to an alternate data stream. This works fine on all but one machine (Windows Server 2003 SP2). Instead, CreateFile returns ERROR_DISK_FULL when I try to create an alternate data stream (on the root directory). I don't find the reason for this result, because... There's plenty of space on that drive. The drive is NTFS formatted (due to GetVolumeInformation). The drive supports altenate data streams (due to GetVolumeInformation). Edit: I can provide some more information about what the reason not is: I added many streams on a test system which didn't show the error and wondered if the error might occur. It didn't. Instead after about 2000 Streams with long file names another error occurred and persisted: 1450 (ERROR_NO_SYSTEM_RESOURCES). EDIT: Here is an example for one of the used file names: char szStreamFileName[] = "C:\\:abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnoqrstuvwxyz012345"; EDIT: Our customer uses some corporate antivirus software from Avira on this server. Maybe this is the reason (Alternate data streams can be abused by malware).

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  • Prevent TEXTAREAs scroll by themselves on IE8

    - by Justin Grant
    IE8 has a known bug (per connect.microsoft.com) where typing or pasting text into a TEXTAREA element will cause the textarea to scroll by itself. This is hugely annoying and shows up in many community sites, including Wikipedia. The repro is this: open the HTML below with IE8 (or use any long page on wikipedia which will exhibit the same problem until they fix it) size the browser full-screen paste a few pages of text into the TEXTAREA move the scrollbar to the middle position now type one character into the textarea Expected: nothing happens Actual: scrossing happens on its own, and the insertion point ends up near the bottom of the textarea! Below is repro HTML (can also see this live on the web here: http://en.wikipedia.org/w/index.php?title=Text_box&action=edit) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <body> <div style="width: 80%"> <textarea rows="20" cols="80" style="width:100%;" ></textarea> </div> </body> </html>

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  • UriMapper Problem

    - by jsop
    I have the following xaml (nonessential markup removed in the interest of brevity): <navigation:Frame x:Name="ContentFrame" > <navigation:Frame.UriMapper> <uriMapper:UriMapper> <uriMapper:UriMapping Uri="/{pageName}" MappedUri="/Views/{pageName}.xaml"/> <uriMapper:UriMapping Uri="/FMChart/{metricID}/{orgID}" MappedUri="/Views/FMChart.xaml?metricID={metricID}&orgID={orgID}"/> </navigation:Frame.UriMapper> </navigation:Frame.UriMapper> </navigation:Frame> I'm creating the HyperLinkButton objects dynamically (in code), like so: int metricID = 1; int orgID = 1; HyperlinkButton button = new HyperlinkButton(); button.Name = Guid.NewGuid().ToString(); button.TargetName = "ContentFrame"; // this string doesn't work string url = string.Format("/FMChart/{0}/{1}", metricID, orgID); button.NavigateUri = new Uri(url, UriKind.Relative); When I click the bbutton, the browser renders a blank page, and eventually presents me with a REALLY long stack trace (InvalidOperation exception). If I take the parameters out of th indicated line: string url = "/FMChart"; ...it works as expected (brings up the desired page). I've also tried the following strings: /FMChart/{0}&{1} /FMChart/{0}& amp;{1} What am I doing wrong?

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  • How to query MySQL for exact length and exact UTF-8 characters

    - by oskarae
    I have table with words dictionary in my language (latvian). CREATE TABLE words ( value varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; And let's say it has 3 words inside: INSERT INTO words (value) VALUES ('teja'); INSERT INTO words (value) VALUES ('vejš'); INSERT INTO words (value) VALUES ('feja'); What I want to do is I want to find all words that is exactly 4 characters long and where second character is 'e' and third character is 'j' For me it feels that correct query would be: SELECT * FROM words WHERE value LIKE '_ej_'; But problem with this query is that it returs not 2 entries ('teja','vejš') but all three. As I understand it is because internally MySQL converts strings to some ASCII representation? Then there is BINARY addition possible for LIKE SELECT * FROM words WHERE value LIKE BINARY '_ej_'; But this also does not return 2 entries ('teja','vejš') but only one ('teja'). I believe this has something to do with UTF-8 2 bytes for non ASCII chars? So question: What MySQL query would return my exact two words ('teja','vejš')? Thank you in advance

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  • PHP in Wordpress Posts - Is this okay?

    - by Thomas
    I've been working with some long lists of information and I've come up with a good way to post it in various formats on my wordpress blog posts. I installed the exec-PHP plugin, which allows you to run php in posts. I then created a new table (NEWTABLE) in my wordpress database and filled that table with names, scores, and other stuff. I was then able to use some pretty simple code to display the information in a wordpress post. Below is an example, but you could really do whatever you wanted. My question is - is there a problem with doing this? with security? or memory? I could just type out all the information in each post, but this is really much nicer. Any thoughts are appreciated. <?php $theResult = mysql_query("SELECT * FROM NEWTABLE WHERE Score < 100 ORDER BY LastName"); while($row = mysql_fetch_array($theResult)) { echo $row['FirstName']; echo " " . $row['LastName']; echo " " . $row['Score']; echo "<br />"; } ?>

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  • How do I protect the trunk from hapless newbies?

    - by Michael Haren
    A coworker relayed the following problem, let's say it's fictional to protect the guilty: A team of 5-10 works on a project which is issue-driven. That is, the typical flow goes like this: a chunk of work (bug, enhancement, etc.) is created as an issue in the issue tracker The issue is assigned to a developer The developer resolves the issue and commits their code changes to the trunk At release time, the frozen, and heavily tested trunk or release branch or whatever is built in release mode and released The problem he's having is that a couple newbies made several bad commits that weren't caught due to an unfortunate chain of events. This was followed by a bad release with a rollback or flurry of hot fixes. One idea we're toying with: Revoke commit access to the trunk for newbies and make them develop on a per-developer branch (we're using SVN): Good: newbies are isolated and can't hurt others Good: committers merge newbie branches with the trunk frequently Good: this enforces rigid code reviews Bad: this is burdensome on the committers (but there's probably no way around it since the code needs reviewed!) Bad: it might make traceability of trunk changes a little tougher since the reviewer would be doing the commit--not too sure on this. Update: Thank you, everyone, for your valuable input. I have concluded that this is far less a code/coder problem than I first presented. The root of the issue is that the release procedure failed to capture and test some poor quality changes to the trunk. Plugging that hole is most important. Relying on the false assumption that code in the trunk is "good" is not the solution. Once that hole--testing--is plugged, mistakes by everyone--newbie or senior--will be caught properly and dealt with accordingly. Next, a greater emphasis on code reviews and mentorship (probably driven by some systematic changes to encourage it) will go a long way toward improving code quality. With those two fixes in place, I don't think something as rigid or draconian as what I proposed above is necessary. Thanks!

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  • Simple Database normalization question...

    - by user365531
    Hi all, I have a quick question regarding a database that I am designing and making sure it is normalized... I have a customer table, with a primary key of customerId. It has a StatusCode column that has a code which reflects the customers account status ie. 1 = Open, 2 = Closed, 3 = Suspended etc... Now I would like to have another field in the customer table that flags whether the account is allowed to be suspended or not... certain customers will be automatically suspended if they break there trading terms... others not... so the relevant table fields will be as so: Customers (CustomerId(PK):StatusCode:IsSuspensionAllowed) Now both fields are dependent on the primary key as you can not determine the status or whether suspensions are allowed on a particular customer unless you know the specific customer, except of course when the IsSuspensionAllowed field is set to YES, the the customer should never have a StatusCode of 3 (Suspended). It seems from the above table design it is possible for this to happen unless a check contraint is added to my table. I can't see how another table could be added to the relational design to enforce this though as it's only in the case where IsSuspensionAllowed is set to YES and StatusCode is set to 3 when the two have a dependence on each other. So after my long winded explanation my question is this: Is this a normalization problem and I'm not seeing a relational design that will enforce this... or is it actually just a business rule that should be enforced with a check contraint and the table is in fact still normalized. Cheers, Steve

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  • Application.ProcessMessages hangs???

    - by X-Ray
    my single threaded delphi 2009 app (not quite yet complete) has started to have a problem with Application.ProcessMessages hanging. my app has a TTimer object that fires every 100 ms to poll an external device. i use Application.ProcessMessages to update the screen when something changes so the app is still responsive. one of these was in a grid OnMouseDown event. in there, it had an Application.ProcessMessages that essentially hung. removing that was no problem except that i soon discovered another Application.ProcessMessages that was also blocking. i think what may be happening to me is that the TTimer is--in the app mode i'm currently debugging--probably taking too long to complete. i have prevented the TTimer.OnTimer event hander from re-entering the same code (see below): procedure TfrmMeas.tmrCheckTimer(Sender: TObject); begin if m_CheckTimerBusy then exit; m_CheckTimerBusy:=true; try PollForAndShowMeasurements; finally m_CheckTimerBusy:=false; end; end; what places would it be a bad practice to call Application.ProcessMessages? OnPaint routines springs to mind as something that wouldn't make sense. any general recommendations? i am surprised to see this kind of problem arise at this point in the development!

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  • JBoss Clustered Service that sends emails from txt file

    - by michael lucas
    I need a little push in the right direction. Here's my problem: I have to create an ultra-reliable service that sends email messages to clients whose addresses are stored in txt file on FTP server. Single txt file may contain unlimited number of entries. Most often the file contains about 300,000 entries. Service exposes interface with just two simple methods: TaskHandle sendEmails(String ftpFilePath); ProcessStatus checkProcessStatus(TaskHandle taskHandle); Method sendEmails() returns TaskHandle by which we can ask for ProcessStatus. For such a service to be reliable clustering is necessary. Processing single txt file might take a long time. Restarting one node in a cluster should have no impact on sending emails. We use JBoss AS 4.2.0 which comes with a nice HASingletonController that ensure one instance of service is running at given time. But once a fail-over happens, the second service should continue work from where the first one stopped. How can I share state between nodes in a cluster in such a way that leaves no possibility of sending some emails twice?

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  • How to display a Dialog on window created using XCreateWindow in QT 4.5.2

    - by Ummar
    I am doing work on project. In which I have developed a full size screen displaying images using XCreateWindow. Now I want to display a dialog on this screen. I have created a QDialog it does'nt show on the full size screen but it is displayed on screen when it is not full size. Any Help. My code for creating screen and dialogbox is as follows XSetWindowAttributes attribs; XClassHint *classhints; XSizeHints *sizehints; int wndwidth, wndheight; long input_mask, ic_input_mask; XEvent xevent; wndwidth = fullscreen ? WidthOfScreen(screen) : width; wndheight = fullscreen ? HeightOfScreen(screen) : height; attribs.background_pixel = BlackPixelOfScreen(screen); attribs.backing_store = ownbackstore ? NotUseful : Always; attribs.override_redirect = fullscreen; wnd = XCreateWindow(display, RootWindowOfScreen(screen), 0, 0, wndwidth, wndheight, 0, CopyFromParent, InputOutput, CopyFromParent, CWBackPixel | CWBackingStore | CWOverrideRedirect, &attribs); XRaiseWindow(display, wnd); //QDialog I want to show on wnd(XCreateWindow) ToolbarDialog *objToolbarDialog= new ToolbarDialog(); objToolbarDialog->setVisible(true); objToolbarDialog->showNormal();

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  • Automatic music rating based on listening habits

    - by marco92w
    I've created a Winamp-like music player in Delphi. Not so complex, of course. Just a simple one. But now I would like to add a more complex feature: Songs in the library should be automatically rated based on the user's listening habits. This means: The application should "understand" if the user likes a song or not. And not only whether he/she likes it but also how much. My approach so far (data which could be used): Simply measure how often a song was played per time. Start counting time when the song was added to the library so that recent songs don't have any disadvantage. Measure how long a song was played on average (minutes). Starting a song but directly change to another one should have a bad influence on the ranking since the user didn't seem to like the song. ... Could you please help me with this problem? I would just like to have some ideas. I don't need the implementation in Delphi.

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  • No Buffer Space available(maximum connection reached?) Form Postgres EDB Driver

    - by Listening.Platform
    We are facing an exception while connecting to database through our java application. The stack trace is as follows com.edb.util.PSQLException: The connection attempt failed. at com.edb.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:189) at com.edb.core.ConnectionFactory.openConnection(ConnectionFactory.java:64) at com.edb.jdbc2.AbstractJdbc2Connection.<init>(AbstractJdbc2Connection.java:161) at com.edb.jdbc3.AbstractJdbc3Connection.<init>(AbstractJdbc3Connection.java:30) at com.edb.jdbc3.Jdbc3Connection.<init>(Jdbc3Connection.java:24) at com.edb.Driver.makeConnection(Driver.java:391) at com.edb.Driver.connect(Driver.java:266) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) ... 12 more Caused by: java.net.SocketException: No buffer space available (maximum connections reached?): connect at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(Unknown Source) at java.net.PlainSocketImpl.connectToAddress(Unknown Source) at java.net.PlainSocketImpl.connect(Unknown Source) at java.net.SocksSocketImpl.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.<init>(Unknown Source) at java.net.Socket.<init>(Unknown Source) at com.edb.core.PGStream.<init>(PGStream.java:70) at com.edb.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:115) ... 20 more When the error occured we were not able to connect to internet and DB and had to reboot the system. But the error occured again after 3 days at same code i.e while connecting to DB. We checked TCP connections using netstat. But there were not many TCP connections i.e it has not reached the max limit. Our application has multiple long running Java processes that pools the DB connections (not more than 60) and keeps it alive for firing the next query (as it has to poll the DB every 2 seconds). Some of the queries in our application are joining large tables (10 million records) to get the related data. We are using following System and applications Windows 2003 server SP2 Java 1.6 Postgres Plus Advanced server 8.4 Database edb-jdbc14.jar driver for connection DB from Java We have used the default configuration of Postgres DB except increasing the connection to 120 from 100. Has anybody encountred the same error with postgres edb driver? Can anybody help us finding the solution?

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  • Linux time sample based profiler.

    - by Caspin
    short version: Is there a good time based sampling profiler for Linux? long version: I generally use OProfile to optimize my applications. I recently found a shortcoming that has me wondering. The problem was a tight loop spawning c++filt to demangle a c++ name. I only stumbled upon the code by accident while chasing down another bottleneck. The OProfile didn't show anything unusual about the code so I almost ignored it but my code sense told me to optimize the call and see what happened. I changed the popen of c++filt to abi::__cxa_demangle. The runtime went from more than a minute to a little over a second. About a x60 speed up. Is there a way I could have configured OProfile to flag the popen call? As the profile data sits now OProfile thinks the bottle neck was the heap and std::string calls (which BTW once optimized dropped the runtime to less than a second, more than x2 speed up). Here is my OProfile configuration: $ sudo opcontrol --status Daemon not running Event 0: CPU_CLK_UNHALTED:90000:0:1:1 Separate options: library vmlinux file: none Image filter: /path/to/excutable Call-graph depth: 7 Buffer size: 65536 Is there another profiler for Linux that could have found the bottleneck? I suspect the issue is that OProfile only logs its samples to the currently running process. I'd like it to always log its samples to the process I'm profiling. So if the process is currently switched out (blocking on IO or a popen call) OProfile would just place its sample at the blocked call. If I can't fix this, OProfile will only be useful when the executable is pushing near 100% CPU. It can't help with executables that that have inefficient blocking calls.

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