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• Rendering a Long Document on iPad

  - by benjismith

  I'm implementing a document viewer with highlighting/annotation capabilities for a custom document format on iPad. The documents are kind of long (100 to 200 pages, if printed on paper) and I've had a hard time finding the right approach. Here are the requirments: 1) Basic rich-text styling: control of left/right margins. Control of font name, size, foreground/background color, and line spacing. Bold, italics, underline, etc. 2) Selection and highlighting of arbitrary text regions (not limited to paragraph boundaries, like in Safari/UIWebView). 3) Customization of the Cut/Copy/Paste popup (what is that thing called anyhow? UIActionBar?) This is one of the essential requirements of the app. My first implementation was based on UIWebView. I just rendered the document as HTML with CSS for text styling. But I couldn't get the kind of text selection behavior I wanted (across paragraph boundaries) and the UIActionBar can't be customized from within UIWebView. So I started working on a javascript approach, faking the device text-selection behavior using JQuery to trap touch events and dynamically modifying the DOM to change the background color of selected regions of text. I built a fake UIActionBar control as a hidden DIV, positioning it and unhiding it whenever there was an active selection region. Not too shabby. The main problem is that it's SLOOOOOOOW. Scrolling through the document is nice and quick, but dynamically changing the DOM is not very snappy. Plus, I couldn't figure out how to recreate the magnifier loupe, so my fake text-selection GUI doesn't look quite the same as the native implementation. Also, I haven't yet implemented the communication bridge between the javascript layer and the objective-c layer (where the rest of the app lives), but it was shaping up to be a huge hassle. So I've been looking at CoreText, but there are precious few examples on the web. I spent a little time with this simple little demo: http://github.com/jonasschnelli/I7CoreTextExample/ It shows how to use CoreText to draw an NSAttributedText string into a UIView. But it has its own problems: It doesn't implement text-selection behavior, and it doesn't present a UIActionBar, so I don't have any idea how to make that happen. And, more importantly, it tries to draw the entire document all at once, with significant performance degradations for long documents. My documents can have thousands of paragraphs, and less than 1% of the document is ever on screen at a time. On the plus side, these documents already contain precise formatting information. I know the exact page-position of every line of text, so I don't need a layout engine. Does anyone know how to implement this sort of view using CoreText? I understand that a full-fledged implementation is overkill for a question like this, but I'm looking for a good CoreText example with a few basic requirements: 1) Precise layout & formatting control (using the formatting metrics and text styles I've already calculated). 2) Arbitrary selection of text. 3) Customization of the UIActionBar. 4) Efficient recycling of resources for off-screen objects. I'd be happy to implement my own recycling when text elements scroll off-screen, but wouldn't that require re-implementing UIScrollView? I'm brand-new to iPhone development, and still getting used to Objective-C, but I've been working in other languages (Java, C#, flex/actionscript, etc) for more than ten years, so I feel confident in my ability to get the work done, if only I had a better feel for the iPhone SDK and the common coding patterns for stuff like this. Is it just me, or does the SDK documentation really suck? Anyhow, thanks for your help!

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• How to implement dynamic binary search for search and insert operations of n element (C or C++)

  - by iecut

  The idea is to use multiple arrays, each of length 2^k, to store n elements, according to binary representation of n.Each array is sorted and different arrays are not ordered in any way. In the above mentioned data structure, SEARCH is carried out by a sequence of binary search on each array. INSERT is carried out by a sequence of merge of arrays of the same length until an empty array is reached. More Detail: Lets suppose we have a vertical array of length 2^k and to each node of that array there attached horizontal array of length 2^k. That is, to the first node of vertical array, a horizontal array of length 2^0=1 is connected,to the second node of vertical array, a horizontal array of length 2^1= 2 is connected and so on. So the insert is first carried out in the first horizontal array, for the second insert the first array becomes empty and second horizontal array is full with 2 elements, for the third insert 1st and 2nd array horiz. array are filled and so on. I implemented the normal binary search for search and insert as follows: int main() { int a[20]= {0}; int n, i, j, temp; int *beg, *end, *mid, target; printf(" enter the total integers you want to enter (make it less then 20):\n"); scanf("%d", &n); if (n = 20) return 0; printf(" enter the integer array elements:\n" ); for(i = 0; i < n; i++) { scanf("%d", &a[i]); } // sort the loaded array, binary search! for(i = 0; i < n-1; i++) { for(j = 0; j < n-i-1; j++) { if (a[j+1] < a[j]) { temp = a[j]; a[j] = a[j+1]; a[j+1] = temp; } } } printf(" the sorted numbers are:"); for(i = 0; i < n; i++) { printf("%d ", a[i]); } // point to beginning and end of the array beg = &a[0]; end = &a[n]; // use n = one element past the loaded array! // mid should point somewhere in the middle of these addresses mid = beg += n/2; printf("\n enter the number to be searched:"); scanf("%d",&target); // binary search, there is an AND in the middle of while()!!! while((beg <= end) && (*mid != target)) { // is the target in lower or upper half? if (target < *mid) { end = mid - 1; // new end n = n/2; mid = beg += n/2; // new middle } else { beg = mid + 1; // new beginning n = n/2; mid = beg += n/2; // new middle } } // find the target? if (*mid == target) { printf("\n %d found!", target); } else { printf("\n %d not found!", target); } getchar(); // trap enter getchar(); // wait return 0; } Could anyone please suggest how to modify this program or a new program to implement dynamic binary search that works as explained above!!

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• Performance Optimization &ndash; It Is Faster When You Can Measure It

  - by Alois Kraus

  Performance optimization in bigger systems is hard because the measured numbers can vary greatly depending on the measurement method of your choice. To measure execution timing of specific methods in your application you usually use Time Measurement Method Potential Pitfalls Stopwatch Most accurate method on recent processors. Internally it uses the RDTSC instruction. Since the counter is processor specific you can get greatly different values when your thread is scheduled to another core or the core goes into a power saving mode. But things do change luckily: Intel's Designer's vol3b, section 16.11.1 "16.11.1 Invariant TSC The time stamp counter in newer processors may support an enhancement, referred to as invariant TSC. Processor's support for invariant TSC is indicated by CPUID.80000007H:EDX[8]. The invariant TSC will run at a constant rate in all ACPI P-, C-. and T-states. This is the architectural behavior moving forward. On processors with invariant TSC support, the OS may use the TSC for wall clock timer services (instead of ACPI or HPET timers). TSC reads are much more efficient and do not incur the overhead associated with a ring transition or access to a platform resource." DateTime.Now Good but it has only a resolution of 16ms which can be not enough if you want more accuracy.   Reporting Method Potential Pitfalls Console.WriteLine Ok if not called too often. Debug.Print Are you really measuring performance with Debug Builds? Shame on you. Trace.WriteLine Better but you need to plug in some good output listener like a trace file. But be aware that the first time you call this method it will read your app.config and deserialize your system.diagnostics section which does also take time.   In general it is a good idea to use some tracing library which does measure the timing for you and you only need to decorate some methods with tracing so you can later verify if something has changed for the better or worse. In my previous article I did compare measuring performance with quantum mechanics. This analogy does work surprising well. When you measure a quantum system there is a lower limit how accurately you can measure something. The Heisenberg uncertainty relation does tell us that you cannot measure of a quantum system the impulse and location of a particle at the same time with infinite accuracy. For programmers the two variables are execution time and memory allocations. If you try to measure the timings of all methods in your application you will need to store them somewhere. The fastest storage space besides the CPU cache is the memory. But if your timing values do consume all available memory there is no memory left for the actual application to run. On the other hand if you try to record all memory allocations of your application you will also need to store the data somewhere. This will cost you memory and execution time. These constraints are always there and regardless how good the marketing of tool vendors for performance and memory profilers are: Any measurement will disturb the system in a non predictable way. Commercial tool vendors will tell you they do calculate this overhead and subtract it from the measured values to give you the most accurate values but in reality it is not entirely true. After falling into the trap to trust the profiler timings several times I have got into the habit to Measure with a profiler to get an idea where potential bottlenecks are. Measure again with tracing only the specific methods to check if this method is really worth optimizing. Optimize it Measure again. Be surprised that your optimization has made things worse. Think harder Implement something that really works. Measure again Finished! - Or look for the next bottleneck. Recently I have looked into issues with serialization performance. For serialization DataContractSerializer was used and I was not sure if XML is really the most optimal wire format. After looking around I have found protobuf-net which uses Googles Protocol Buffer format which is a compact binary serialization format. What is good for Google should be good for us. A small sample app to check out performance was a matter of minutes: using ProtoBuf; using System; using System.Diagnostics; using System.IO; using System.Reflection; using System.Runtime.Serialization; [DataContract, Serializable] class Data { [DataMember(Order=1)] public int IntValue { get; set; } [DataMember(Order = 2)] public string StringValue { get; set; } [DataMember(Order = 3)] public bool IsActivated { get; set; } [DataMember(Order = 4)] public BindingFlags Flags { get; set; } } class Program { static MemoryStream _Stream = new MemoryStream(); static MemoryStream Stream { get { _Stream.Position = 0; _Stream.SetLength(0); return _Stream; } } static void Main(string[] args) { DataContractSerializer ser = new DataContractSerializer(typeof(Data)); Data data = new Data { IntValue = 100, IsActivated = true, StringValue = "Hi this is a small string value to check if serialization does work as expected" }; var sw = Stopwatch.StartNew(); int Runs = 1000 * 1000; for (int i = 0; i < Runs; i++) { //ser.WriteObject(Stream, data); Serializer.Serialize<Data>(Stream, data); } sw.Stop(); Console.WriteLine("Did take {0:N0}ms for {1:N0} objects", sw.Elapsed.TotalMilliseconds, Runs); Console.ReadLine(); } } The results are indeed promising: Serializer Time in ms N objects protobuf-net   807 1000000 DataContract 4402 1000000 Nearly a factor 5 faster and a much more compact wire format. Lets use it! After switching over to protbuf-net the transfered wire data has dropped by a factor two (good) and the performance has worsened by nearly a factor two. How is that possible? We have measured it? Protobuf-net is much faster! As it turns out protobuf-net is faster but it has a cost: For the first time a type is de/serialized it does use some very smart code-gen which does not come for free. Lets try to measure this one by setting of our performance test app the Runs value not to one million but to 1. Serializer Time in ms N objects protobuf-net 85 1 DataContract 24 1 The code-gen overhead is significant and can take up to 200ms for more complex types. The break even point where the code-gen cost is amortized by its faster serialization performance is (assuming small objects) somewhere between 20.000-40.000 serialized objects. As it turned out my specific scenario involved about 100 types and 1000 serializations in total. That explains why the good old DataContractSerializer is not so easy to take out of business. The final approach I ended up was to reduce the number of types and to serialize primitive types via BinaryWriter directly which turned out to be a pretty good alternative. It sounded good until I measured again and found that my optimizations so far do not help much. After looking more deeper at the profiling data I did found that one of the 1000 calls did take 50% of the time. So how do I find out which call it was? Normal profilers do fail short at this discipline. A (totally undeserved) relatively unknown profiler is SpeedTrace which does unlike normal profilers create traces of your applications by instrumenting your IL code at runtime. This way you can look at the full call stack of the one slow serializer call to find out if this stack was something special. Unfortunately the call stack showed nothing special. But luckily I have my own tracing as well and I could see that the slow serializer call did happen during the serialization of a bool value. When you encounter after much analysis something unreasonable you cannot explain it then the chances are good that your thread was suspended by the garbage collector. If there is a problem with excessive GCs remains to be investigated but so far the serialization performance seems to be mostly ok.  When you do profile a complex system with many interconnected processes you can never be sure that the timings you just did measure are accurate at all. Some process might be hitting the disc slowing things down for all other processes for some seconds as well. There is a big difference between warm and cold startup. If you restart all processes you can basically forget the first run because of the OS disc cache, JIT and GCs make the measured timings very flexible. When you are in need of a random number generator you should measure cold startup times of a sufficiently complex system. After the first run you can try again getting different and much lower numbers. Now try again at least two times to get some feeling how stable the numbers are. Oh and try to do the same thing the next day. It might be that the bottleneck you found yesterday is gone today. Thanks to GC and other random stuff it can become pretty hard to find stuff worth optimizing if no big bottlenecks except bloatloads of code are left anymore. When I have found a spot worth optimizing I do make the code changes and do measure again to check if something has changed. If it has got slower and I am certain that my change should have made it faster I can blame the GC again. The thing is that if you optimize stuff and you allocate less objects the GC times will shift to some other location. If you are unlucky it will make your faster working code slower because you see now GCs at times where none were before. This is where the stuff does get really tricky. A safe escape hatch is to create a repro of the slow code in an isolated application so you can change things fast in a reliable manner. Then the normal profilers do also start working again. As Vance Morrison does point out it is much more complex to profile a system against the wall clock compared to optimize for CPU time. The reason is that for wall clock time analysis you need to understand how your system does work and which threads (if you have not one but perhaps 20) are causing a visible delay to the end user and which threads can wait a long time without affecting the user experience at all. Next time: Commercial profiler shootout.

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• Set-Cookie Headers getting stripped in ASP.NET HttpHandlers

  - by Rick Strahl

  Yikes, I ran into a real bummer of an edge case yesterday in one of my older low level handler implementations (for West Wind Web Connection in this case). Basically this handler is a connector for a backend Web framework that creates self contained HTTP output. An ASP.NET Handler captures the full output, and then shoves the result down the ASP.NET Response object pipeline writing out the content into the Response.OutputStream and seperately sending the HttpHeaders in the Response.Headers collection. The headers turned out to be the problem and specifically Http Cookies, which for some reason ended up getting stripped out in some scenarios. My handler works like this: Basically the HTTP response from the backend app would return a full set of HTTP headers plus the content. The ASP.NET handler would read the headers one at a time and then dump them out via Response.AppendHeader(). But I found that in some situations Set-Cookie headers sent along were simply stripped inside of the Http Handler. After a bunch of back and forth with some folks from Microsoft (thanks Damien and Levi!) I managed to pin this down to a very narrow edge scenario. It's easiest to demonstrate the problem with a simple example HttpHandler implementation. The following simulates the very much simplified output generation process that fails in my handler. Specifically I have a couple of headers including a Set-Cookie header and some output that gets written into the Response object.using System.Web; namespace wwThreads { public class Handler : IHttpHandler { /* NOTE: * * Run as a web.config set handler (see entry below) * * Best way is to look at the HTTP Headers in Fiddler * or Chrome/FireBug/IE tools and look for the * WWHTREADSID cookie in the outgoing Response headers * ( If the cookie is not there you see the problem! ) */ public void ProcessRequest(HttpContext context) { HttpRequest request = context.Request; HttpResponse response = context.Response; // If ClearHeaders is used Set-Cookie header gets removed! // if commented header is sent... response.ClearHeaders(); response.ClearContent(); // Demonstrate that other headers make it response.AppendHeader("RequestId", "asdasdasd"); // This cookie gets removed when ClearHeaders above is called // When ClearHEaders is omitted above the cookie renders response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); // *** This always works, even when explicit // Set-Cookie above fails and ClearHeaders is called //response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); response.Write(@"Output was created.<hr/> Check output with Fiddler or HTTP Proxy to see whether cookie was sent."); } public bool IsReusable { get { return false; } } } } In order to see the problem behavior this code has to be inside of an HttpHandler, and specifically in a handler defined in web.config with: <add name=".ck_handler" path="handler.ck" verb="*" type="wwThreads.Handler" preCondition="integratedMode" /> Note: Oddly enough this problem manifests only when configured through web.config, not in an ASHX handler, nor if you paste that same code into an ASPX page or MVC controller. What's the problem exactly? The code above simulates the more complex code in my live handler that picks up the HTTP response from the backend application and then peels out the headers and sends them one at a time via Response.AppendHeader. One of the headers in my app can be one or more Set-Cookie. I found that the Set-Cookie headers were not making it into the Response headers output. Here's the Chrome Http Inspector trace: Notice, no Set-Cookie header in the Response headers! Now, running the very same request after removing the call to Response.ClearHeaders() command, the cookie header shows up just fine: As you might expect it took a while to track this down. At first I thought my backend was not sending the headers but after closer checks I found that indeed the headers were set in the backend HTTP response, and they were indeed getting set via Response.AppendHeader() in the handler code. Yet, no cookie in the output. In the simulated example the problem is this line:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); which in my live code is more dynamic ( ie. AppendHeader(token[0],token[1[]) )as it parses through the headers. Bizzaro Land: Response.ClearHeaders() causes Cookie to get stripped Now, here is where it really gets bizarre: The problem occurs only if: Response.ClearHeaders() was called before headers are added It only occurs in Http Handlers declared in web.config Clearly this is an edge of an edge case but of course - knowing my relationship with Mr. Murphy - I ended up running smack into this problem. So in the code above if you remove the call to ClearHeaders(), the cookie gets set!  Add it back in and the cookie is not there. If I run the above code in an ASHX handler it works. If I paste the same code (with a Response.End()) into an ASPX page, or MVC controller it all works. Only in the HttpHandler configured through Web.config does it fail! Cue the Twilight Zone Music. Workarounds As is often the case the fix for this once you know the problem is not too difficult. The difficulty lies in tracking inconsistencies like this down. Luckily there are a few simple workarounds for the Cookie issue. Don't use AppendHeader for Cookies The easiest and obvious solution to this problem is simply not use Response.AppendHeader() to set Cookies. Duh! Under normal circumstances in application level code there's rarely a reason to write out a cookie like this:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); but rather create the cookie using the Response.Cookies collection:response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); Unfortunately, in my case where I dynamically read headers from the original output and then dynamically  write header key value pairs back  programmatically into the Response.Headers collection, I actually don't look at each header specifically so in my case the cookie is just another header. My first thought was to simply trap for the Set-Cookie header and then parse out the cookie and create a Cookie object instead. But given that cookies can have a lot of different options this is not exactly trivial, plus I don't really want to fuck around with cookie values which can be notoriously brittle. Don't use Response.ClearHeaders() The real mystery in all this is why calling Response.ClearHeaders() prevents a cookie value later written with Response.AppendHeader() to fail. I fired up Reflector and took a quick look at System.Web and HttpResponse.ClearHeaders. There's all sorts of resetting going on but nothing that seems to indicate that headers should be removed later on in the request. The code in ClearHeaders() does access the HttpWorkerRequest, which is the low level interface directly into IIS, and so I suspect it's actually IIS that's stripping the headers and not ASP.NET, but it's hard to know. Somebody from Microsoft and the IIS team would have to comment on that. In my application it's probably safe to simply skip ClearHeaders() in my handler. The ClearHeaders/ClearContent was mainly for safety but after reviewing my code there really should never be a reason that headers would be set prior to this method firing. However, if for whatever reason headers do need to be cleared, it's easy enough to manually clear the headers out:private void RemoveHeaders(HttpResponse response) { List<string> headers = new List<string>(); foreach (string header in response.Headers) { headers.Add(header); } foreach (string header in headers) { response.Headers.Remove(header); } response.Cookies.Clear(); } Now I can replace the call the Response.ClearHeaders() and I don't get the funky side-effects from Response.ClearHeaders(). Summary I realize this is a total edge case as this occurs only in HttpHandlers that are manually configured. It looks like you'll never run into this in any of the higher level ASP.NET frameworks or even in ASHX handlers - only web.config defined handlers - which is really, really odd. After all those frameworks use the same underlying ASP.NET architecture. Hopefully somebody from Microsoft has an idea what crazy dependency was triggered here to make this fail. IAC, there are workarounds to this should you run into it, although I bet when you do run into it, it'll likely take a bit of time to find the problem or even this post in a search because it's not easily to correlate the problem to the solution. It's quite possible that more than cookies are affected by this behavior. Searching for a solution I read a few other accounts where headers like Referer were mysteriously disappearing, and it's possible that something similar is happening in those cases. Again, extreme edge case, but I'm writing this up here as documentation for myself and possibly some others that might have run into this. © Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET   IIS7   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Negamax implementation doesn't appear to work with tic-tac-toe

  - by George Jiglau

  I've implemented Negamax as it can be found on wikipedia, which includes alpha/beta pruning. However, it seems to favor a losing move, which should be an invalid result. The game is Tic-Tac-Toe, I've abstracted most of the game play so it should be rather easy to spot an error within the algorithm. Here is the code, nextMove, negamax or evaluate are probably the functions that contain the fault: #include <list> #include <climits> #include <iostream> //#define DEBUG 1 using namespace std; struct Move { int row, col; Move(int row, int col) : row(row), col(col) { } Move(const Move& m) { row = m.row; col = m.col; } }; struct Board { char player; char opponent; char board[3][3]; Board() { } void read(istream& stream) { stream >> player; opponent = player == 'X' ? 'O' : 'X'; for(int row = 0; row < 3; row++) { for(int col = 0; col < 3; col++) { char playa; stream >> playa; board[row][col] = playa == '_' ? 0 : playa == player ? 1 : -1; } } } void print(ostream& stream) { for(int row = 0; row < 3; row++) { for(int col = 0; col < 3; col++) { switch(board[row][col]) { case -1: stream << opponent; break; case 0: stream << '_'; break; case 1: stream << player; break; } } stream << endl; } } void do_move(const Move& move, int player) { board[move.row][move.col] = player; } void undo_move(const Move& move) { board[move.row][move.col] = 0; } bool isWon() { if (board[0][0] != 0) { if (board[0][0] == board[0][1] && board[0][1] == board[0][2]) return true; if (board[0][0] == board[1][0] && board[1][0] == board[2][0]) return true; } if (board[2][2] != 0) { if (board[2][0] == board[2][1] && board[2][1] == board[2][2]) return true; if (board[0][2] == board[1][2] && board[1][2] == board[2][2]) return true; } if (board[1][1] != 0) { if (board[0][1] == board[1][1] && board[1][1] == board[2][1]) return true; if (board[1][0] == board[1][1] && board[1][1] == board[1][2]) return true; if (board[0][0] == board[1][1] && board[1][1] == board[2][2]) return true; if (board[0][2] == board [1][1] && board[1][1] == board[2][0]) return true; } return false; } list<Move> getMoves() { list<Move> moveList; for(int row = 0; row < 3; row++) for(int col = 0; col < 3; col++) if (board[row][col] == 0) moveList.push_back(Move(row, col)); return moveList; } }; ostream& operator<< (ostream& stream, Board& board) { board.print(stream); return stream; } istream& operator>> (istream& stream, Board& board) { board.read(stream); return stream; } int evaluate(Board& board) { int score = board.isWon() ? 100 : 0; for(int row = 0; row < 3; row++) for(int col = 0; col < 3; col++) if (board.board[row][col] == 0) score += 1; return score; } int negamax(Board& board, int depth, int player, int alpha, int beta) { if (board.isWon() || depth <= 0) { #if DEBUG > 1 cout << "Found winner board at depth " << depth << endl; cout << board << endl; #endif return player * evaluate(board); } list<Move> allMoves = board.getMoves(); if (allMoves.size() == 0) return player * evaluate(board); for(list<Move>::iterator it = allMoves.begin(); it != allMoves.end(); it++) { board.do_move(*it, -player); int val = -negamax(board, depth - 1, -player, -beta, -alpha); board.undo_move(*it); if (val >= beta) return val; if (val > alpha) alpha = val; } return alpha; } void nextMove(Board& board) { list<Move> allMoves = board.getMoves(); Move* bestMove = NULL; int bestScore = INT_MIN; for(list<Move>::iterator it = allMoves.begin(); it != allMoves.end(); it++) { board.do_move(*it, 1); int score = -negamax(board, 100, 1, INT_MIN + 1, INT_MAX); board.undo_move(*it); #if DEBUG cout << it->row << ' ' << it->col << " = " << score << endl; #endif if (score > bestScore) { bestMove = &*it; bestScore = score; } } if (!bestMove) return; cout << bestMove->row << ' ' << bestMove->col << endl; #if DEBUG board.do_move(*bestMove, 1); cout << board; #endif } int main() { Board board; cin >> board; #if DEBUG cout << "Starting board:" << endl; cout << board; #endif nextMove(board); return 0; } Giving this input: O X__ ___ ___ The algorithm chooses to place a piece at 0, 1, causing a guaranteed loss, do to this trap(nothing can be done to win or end in a draw): XO_ X__ ___ Perhaps it has something to do with the evaluation function? If so, how could I fix it?

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• Combine config-paramters with parameters passed from commanline

  - by Frederik

  I have created a SSIS-package that imports a file into a table (simple enough). I have some variables, a few set in a config-file such as server, database, importfolder. at runtime I want to pass the filename. This is done through a stored procedure using dtexec. When setting the paramters throught the configfile it works fine also when setting all parameters in the procedure and passing them with the \Set statement (se below). when I try to combine the config-version with settings parameters on the fly I get an error refering to the config-files path that was set at design time. Has anybody come across this and found a solution for it? Regards Frederik DECLARE @SSISSTR VARCHAR(8000), @DataBaseServer VARCHAR(100), @DataBaseName VARCHAR(100), @PackageFilePath VARCHAR(200), @ImportFolder VARCHAR(200), @HandledFolder VARCHAR(200), @ConfigFilePath VARCHAR(200), @SSISreturncode INT; /* DEBUGGING DECLARE @FileName VARCHAR(100), @SelectionId INT SET @FileName = 'Test.csv'; SET @SelectionId = 366; */ SET @PackageFilePath = '/FILE "Y:\SSIS\Packages\PostalCodeSelectionImport\ImportPackage.dtsx" '; SET @DataBaseServer = 'STOSWVUTVDB01\DEV_BSE'; SET @DataBaseName = 'BSE_ODR'; SET @ImportFolder = '\\Stoswvutvbse01\Application\FileLoadArea\ODR\\'; SET @HandledFolder = '\\Stoswvutvbse01\Application\FileLoadArea\ODR\Handled\\'; --SET @ConfigFilePath = '/CONFIGFILE "Y:\SSIS\Packages\PostalCodeSelectionImport\Configuration\DEV_BSE.dtsConfig" '; ----now making "dtexec" SQL from dynamic values SET @SSISSTR = 'DTEXEC ' + @PackageFilePath; -- + @ConfigFilePath; SET @SSISSTR = @SSISSTR + ' /SET \Package.Variables[User::SelectionId].Properties[Value];' + CAST( @SelectionId AS VARCHAR(12)); SET @SSISSTR = @SSISSTR + ' /SET \Package.Variables[User::DataBaseServer].Properties[Value];"' + @DataBaseServer + '"'; SET @SSISSTR = @SSISSTR + ' /SET \Package.Variables[User::ImportFolder].Properties[Value];"' + @ImportFolder + '" '; SET @SSISSTR = @SSISSTR + ' /SET \Package.Variables[User::DataBaseName].Properties[Value];"' + @DataBaseName + '" '; SET @SSISSTR = @SSISSTR + ' /SET \Package.Variables[User::ImportFileName].Properties[Value];"' + @FileName + '" '; SET @SSISSTR = @SSISSTR + ' /SET \Package.Variables[User::HandledFolder].Properties[Value];"' + @HandledFolder + '" '; -- Now execute dynamic SQL by using EXEC. EXEC @SSISreturncode = xp_cmdshell @SSISSTR;

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• Disable Windows 8 edge gestures/hot corners for multi-touch applications while running in full screen

  - by Bondye

  I have a full screen AS3 game maby with Adobe AIR that runs in Windows 7. In this game it may not be easy to exit (think about kiosk mode, only exit by pressing esc and enter a password). Now I want this game to run in Windows 8. The game is working like expected but the anoying things are these edge gestures/hot corners (left, top, right, bottom) and the shortcuts. I've read articles but none helped me. People talk about registery edits, but I dont get this working + the user needs to restart his/hers computer. I want to open my game, turn off gestures/hot corners and when the game closes the gestures/hot corners need to come back available again. I have seen some applications doing the same what I want to accomplish. I found this so I am able to detect the gestures. But how to ignore they're actions? I also read ASUS Smart Gestures but this is for the touch-pad. And I have tried Classic Shell but I need to disable the edge gestures/hot corners without such programs, just on-the-fly. I also found this but I don't know how to implement this. HRESULT SetTouchDisableProperty(HWND hwnd, BOOL fDisableTouch) { IPropertyStore* pPropStore; HRESULT hrReturnValue = SHGetPropertyStoreForWindow(hwnd, IID_PPV_ARGS(&pPropStore)); if (SUCCEEDED(hrReturnValue)) { PROPVARIANT var; var.vt = VT_BOOL; var.boolVal = fDisableTouch ? VARIANT_TRUE : VARIANT_FALSE; hrReturnValue = pPropStore->SetValue(PKEY_EdgeGesture_DisableTouchWhenFullscreen, var); pPropStore->Release(); } return hrReturnValue; } Does anyone know how I can do this? Or point me into the right direction? I have tried some in C# and C++, but I aint a skilled C#/C++ developer. Also the game is made in AS3 so it will be hard to implement this in C#/C++. I work on the Lenovo aio (All in one) with Windows 8.

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• jQuery monitoring form field created by AJAX query

  - by Jon Rhoades

  Preface: I am sure this is incredibly simple, but I have searched this site & the jQuery site and can't figure out the right search term to get an answer - please excuse my ignorance! I am adding additional form fields using jQuery's ajax function and need to then apply additional ajax functions to those fields but can't seem to get jQuery to monitor these on the fly form fields. How can I get jQuery to use these new fields? $(document).ready(function() { $('#formField').hide(); $('.lnk').click(function() { var t = this.id; $('#formField').show(400); $('#form').load('loader.php?val=' + t); }); //This works fine if the field is already present var name = $('#name'); var email = $('#email'); $('#uid').keyup(function () { var t = this; if (this.value != this.lastValue) { if (this.timer) clearTimeout(this.timer); this.timer = setTimeout(function () { $.ajax({ url: 'loader.php', data: 'action=getUser&uid=' + t.value, type: 'get', success: function (j) { va = j.split("|"); displayname = va[1]; mail = va[2]; name.val(displayname); email.val(mail); } }); }, 200); this.lastValue = this.value; } }); }); So if the is present in the basic html page the function works, but if it arrives by the $.load function it doesn't - presumably because $(document).ready has already started. I did try: $(document).ready(function() { $('#formField').hide(); $('.lnk').click(function() { var t = this.id; $('#formField').show(400); $('#form').load('loader.php?val=' + t); prepUid(); }); }); function prepUid(){ var name = $('#name'); var email = $('#email'); $('#uid').keyup(function () { snip........... But it didn't seem to work...

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• How to update a user created Bitmap in the Windows API

  - by gamernb

  In my code I quickly generate images on the fly, and I want to display them as quickly as possible. So the first time I create my image, I create a new BITMAP, but instead of deleting the old one and creating a new one for every subsequent image, I just want to copy my data back into the existing one. Here is my code to do both the initial creation and the updating. The creation works just fine, but the updating one doesn't work. BITMAPINFO bi; HBITMAP Frame::CreateBitmap(HWND hwnd, int tol1, int tol2, bool useWhite, bool useBackground) { ZeroMemory(&bi.bmiHeader, sizeof(BITMAPINFOHEADER)); bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER); bi.bmiHeader.biWidth = width; bi.bmiHeader.biHeight = height; bi.bmiHeader.biPlanes = 1; bi.bmiHeader.biBitCount = 24; bi.bmiHeader.biCompression = BI_RGB; ZeroMemory(bi.bmiColors, sizeof(RGBQUAD)); // Allocate memory for bitmap bits int size = height * width; Pixel* newPixels = new Pixel[size]; // Recompute the output //memcpy(newPixels, pixels, size*3); ComputeOutput(newPixels, tol1, tol2, useWhite, useBackground); HBITMAP bitmap = CreateDIBitmap(GetDC(hwnd), &bi.bmiHeader, CBM_INIT, newPixels, &bi, DIB_RGB_COLORS); delete newPixels; return bitmap; } and void Frame::UpdateBitmap(HWND hwnd, HBITMAP bitmap, int tol1, int tol2, bool useWhite, bool useBackground) { ZeroMemory(&bi.bmiHeader, sizeof(BITMAPINFOHEADER)); bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER); HDC hdc = GetDC(hwnd); if(!GetDIBits(hdc, bitmap, 0, bi.bmiHeader.biHeight, NULL, &bi, DIB_RGB_COLORS)) MessageBox(NULL, "Can't get base image info!", "Error!", MB_ICONEXCLAMATION | MB_OK); // Allocate memory for bitmap bits int size = height * width; Pixel* newPixels = new Pixel[size]; // Recompute the output //memcpy(newPixels, pixels, size*3); ComputeOutput(newPixels, tol1, tol2, useWhite, useBackground); // Push back to windows if(!SetDIBits(hdc, bitmap, 0, bi.bmiHeader.biHeight, newPixels, &bi, DIB_RGB_COLORS)) MessageBox(NULL, "Can't set pixel data!", "Error!", MB_ICONEXCLAMATION | MB_OK); delete newPixels; } where the Pixel struct is just this: struct Pixel { unsigned char b, g, r; }; Why does my update function not work. I always get the MessageBox for "Can't set pixel data!" I used code similar to this when I was loading in the original bitmap from file, then editing the data, but now when I manually create it, it doesn't work.

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• DataTable identity column not set after DataAdapter.Update/Refresh on table with "instead of"-trigge

  - by Arno

  Within our unit tests we use plain ADO.NET (DataTable, DataAdapter) for preparing the database resp. checking the results, while the tested components themselves run under NHibernate 2.1. .NET version is 3.5, SqlServer version is 2005. The database tables have identity columns as primary keys. Some tables apply instead-of-insert/update triggers (this is due to backward compatibility, nothing I can change). The triggers generally work like this: create trigger dbo.emp_insert on dbo.emp instead of insert as begin set nocount on insert into emp ... select @@identity end The insert statement issued by the ADO.NET DataAdapter (generated on-the-fly by a thin ADO.NET wrapper) tries to retrieve the identity value back into the DataRow: exec sp_executesql N' insert into emp (...) values (...); select id, ... from emp where id = @@identity ' But the DataRow's id-Column is still 0. When I remove the trigger temporarily, it works fine - the id-Column then holds the identity value set by the database. NHibernate on the other hand uses this kind of insert statement: exec sp_executesql N' insert into emp (...) values (...); select scope_identity() ' This works, the NHibernate POCO has its id property correctly set right after flushing. Which seems a little bit counter-intuitive to me, as I expected the trigger to run in a different scope, hence @@identity should be a better fit than scope_identity(). So I thought no problem, I will apply scope_identity() instead of @@identity under ADO.NET as well. But this has no effect, the DataRow value is still not updated accordingly. And now for the best part: When I copy and paste those two statements from SqlServer profiler into a Management Studio query (that is including "exec sp_executesql"), and run them there, the results seem to be inverse! There the ADO.NET version works, and the NHibernate version doesn't (select scope_identity() returns null). I tried several times to verify, but to no avail. Of course this just shows the resultset coming from the database, whatever happens inside NHibernate and ADO.NET is another topic. Also, several session properties defined by T-SQL SET are different in the two scenarios (Management Studio query vs. application at runtime) This is a real puzzle to me. I would be happy about any insights on that. Thank you!

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• How to avoid using duplicate savepoint names in nested transactions in nested stored procs?

  - by Gary McGill

  I have a pattern that I almost always follow, where if I need to wrap up an operation in a transaction, I do this: BEGIN TRANSACTION SAVE TRANSACTION TX -- Stuff IF @error <> 0 ROLLBACK TRANSACTION TX COMMIT TRANSACTION That's served me well enough in the past, but after years of using this pattern (and copy-pasting the above code), I've suddenly discovered a flaw which comes as a complete shock. Quite often, I'll have a stored procedure calling other stored procedures, all of which use this same pattern. What I've discovered (to my cost) is that because I'm using the same savepoint name everywhere, I can get into a situation where my outer transaction is partially committed - precisely the opposite of the atomicity that I'm trying to achieve. I've put together an example that exhibits the problem. This is a single batch (no nested stored procs), and so it looks a little odd in that you probably wouldn't use the same savepoint name twice in the same batch, but my real-world scenario would be too confusing to post. CREATE TABLE Test (test INTEGER NOT NULL) BEGIN TRAN SAVE TRAN TX BEGIN TRAN SAVE TRAN TX INSERT INTO Test(test) VALUES (1) COMMIT TRAN TX BEGIN TRAN SAVE TRAN TX INSERT INTO Test(test) VALUES (2) COMMIT TRAN TX DELETE FROM Test ROLLBACK TRAN TX COMMIT TRAN TX SELECT * FROM Test DROP TABLE Test When I execute this, it lists one record, with value "1". In other words, even though I rolled back my outer transaction, a record was added to the table. What's happening is that the ROLLBACK TRANSACTION TX at the outer level is rolling back as far as the last SAVE TRANSACTION TX at the inner level. Now that I write this all out, I can see the logic behind it: the server is looking back through the log file, treating it as a linear stream of transactions; it doesn't understand the nesting/hierarchy implied by either the nesting of the transactions (or, in my real-world scenario, by the calls to other stored procedures). So, clearly, I need to start using unique savepoint names instead of blindly using "TX" everywhere. But - and this is where I finally get to the point - is there a way to do this in a copy-pastable way so that I can still use the same code everywhere? Can I auto-generate the savepoint name on the fly somehow? Is there a convention or best-practice for doing this sort of thing? It's not exactly hard to come up with a unique name every time you start a transaction (could base it off the SP name, or somesuch), but I do worry that eventually there would be a conflict - and you wouldn't know about it because rather than causing an error it just silently destroys your data... :-(

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• XML to be validated against multiple xsd schemas

  - by Michael Rusch

  I'm writing the xsd and the code to validate, so I have great control here. I would like to have an upload facility that adds stuff to my application based on an xml file. One part of the xml file should be validated against different schemas based on one of the values in the other part of it. Here's an example to illustrate: <foo> <name>Harold</name> <bar>Alpha</bar> <baz>Mercury</baz> <!-- ... more general info that applies to all foos ... --> <bar-config> <!-- the content here is specific to the bar named "Alpha" --> </bar-config> <baz-config> <!-- the content here is specific to the baz named "Mercury" --> </baz> </foo> In this case, there is some controlled vocabulary for the content of <bar>, and I can handle that part just fine. Then, based on the bar value, the appropriate xml schema should be used to validate the content of bar-config. Similarly for baz and baz-config. The code doing the parsing/validation is written in Java. Not sure how language-dependent the solution will be. Ideally, the solution would permit the xml author to declare the appropriate schema locations and what-not so that s/he could get the xml validated on the fly in a sufficiently smart editor. Also, the possible values for <bar> and <baz> are orthogonal, so I don't want to do this by extension for every possible bar/baz combo. What I mean is, if there are 24 possible bar values/schemas and 8 possible baz values/schemas, I want to be able to write 1 + 24 + 8 = 33 total schemas, instead of 1 * 24 * 8 = 192 total schemas. Also, I'd prefer to NOT break out the bar-config and baz-config into separate xml files if possible. I realize that might make all the problems much easier, as each xml file would have a single schema, but I'm trying to see if there is a good single-xml-file solution.

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• help with jquery ajax and templates in asp.net mvc

  - by NachoF

  So I have a complex form for an IncomeDeclaration. Its going to display a textfield GrossIncome for each Activity that the IncomeDeclaration is related to... this all gets done on the server and works just fine.... the problem is. The User should also be able to add Activities on the fly.. through javascript... so when the user clicks on Add Activity a Dropdown and a textfield must be appended to the bottom the activities list... heres what Ive got so far <tbody id="activities"> @Html.EditorFor(model => model.income.EconomicActivityIncomeDeclarations) </tbody> </table> <a href="#" id="add_activity">Agregar Otra Actividad</a> </fieldset> <script type="text/javascript"> $("#add_activity").click(function () { $.getJSON('/IncomeDeclarations/GetEconomicActivities', function (data) { var select = new Select(); var data = new Array(); for (var i = 0; i < data.length; i++) { var option = new Option(data[i]["name"], data[i]["i"]) //should do something here } //should call the template and append to #activities }); }); </script> <script id="template" type="text/x-jquery-tmpl"> <tr> <td><select name="income.EconomicActivityIncomeDeclarations[${SomeNumber}].EconomicActivityId"> ${MyOptions} </select></td> <td><input type="text" name="income.EconomicActivityIncomeDeclarations[${SomeNumber}].GrossIncome" /></td>> </tr> </script> } The name attribute for both the select and the text_field is key for this to work... otherwise modelbinding wont work... I would think that if the SomeNumber variable is set to new Date.GetTime() model Binding should work just fine... I actually dont see the need of ajax for this but thats another topic.. I just havent figured out a way to do this without ajax... right now I want to get the template to work and append the form elements to the bottom of the list.

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• Code Golf: Evaluating Mathematical Expressions

  - by Noldorin

  Challenge Here is the challenge (of my own invention, though I wouldn't be surprised if it has previously appeared elsewhere on the web). Write a function that takes a single argument that is a string representation of a simple mathematical expression and evaluates it as a floating point value. A "simple expression" may include any of the following: positive or negative decimal numbers, +, -, *, /, (, ). Expressions use (normal) infix notation. Operators should be evaluated in the order they appear, i.e. not as in BODMAS, though brackets should be correctly observed, of course. The function should return the correct result for any possible expression of this form. However, the function does not have to handle malformed expressions (i.e. ones with bad syntax). Examples of expressions: 1 + 3 / -8 = -0.5 (No BODMAS) 2*3*4*5+99 = 219 4 * (9 - 4) / (2 * 6 - 2) + 8 = 10 1 + ((123 * 3 - 69) / 100) = 4 2.45/8.5*9.27+(5*0.0023) = 2.68... Rules I anticipate some form of "cheating"/craftiness here, so please let me forewarn against it! By cheating, I refer to the use of the eval or equivalent function in dynamic languages such as JavaScript or PHP, or equally compiling and executing code on the fly. (I think my specification of "no BODMAS" has pretty much guaranteed this however.) Apart from that, there are no restrictions. I anticipate a few Regex solutions here, but it would be nice to see more than just that. Now, I'm mainly interested in a C#/.NET solution here, but any other language would be perfectly acceptable too (in particular, F# and Python for the functional/mixed approaches). I haven't yet decided whether I'm going to accept the shortest or most ingenious solution (at least for the language) as the answer, but I would welcome any form of solution in any language, except what I've just prohibited above! My Solution I've now posted my C# solution here (403 chars). Update: My new solution has beaten the old one significantly at 294 chars, with the help of a bit of lovely regex! I suspected that this will get easily beaten by some of the languages out there with lighter syntax (particularly the funcional/dynamic ones), and have been proved right, but I'd be curious if someone could beat this in C# still. Update I've seen some very crafty solutions already. Thanks to everyone who has posted one. Although I haven't tested any of them yet, I'm going to trust people and assume they at least work with all of the given examples. Just for the note, re-entrancy (i.e. thread-safety) is not a requirement for the function, though it is a bonus. Format Please post all answers in the following format for the purpose of easy comparison: Language Number of characters: ??? Fully obfuscated function: (code here) Clear/semi-obfuscated function: (code here) Any notes on the algorithm/clever shortcuts it takes.

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• Creating a variable list Pashua, OS X & Bash.

  - by S1syphus

  First of all, for those that don't know pashua is a tool for creating native Aqua dialog windows. An example of what a window config looks like is # pashua_run() # Define what the dialog should be like # Take a look at Pashua's Readme file for more info on the syntax conf=" # Set transparency: 0 is transparent, 1 is opaque *.transparency=0.95 # Set window title *.title = Introducing Pashua # Introductory text tb.type = text tb.default = "HELLO WORLD" tb.height = 276 tb.width = 310 tb.x = 340 tb.y = 44 if [ -e "$icon" ] then # Display Pashua's icon conf="$conf img.type = image img.x = 530 img.y = 255 img.path = $icon" fi if [ -e "$bgimg" ] then # Display background image conf="$conf bg.type = image bg.x = 30 bg.y = 2 bg.path = $bgimg" fi pashua_run "$conf" echo " tb = $tb" The problem is, Pashua can't really get output from stdout, but it can get arguments. Following on from what Dennis Williamson posted here. What ideally it should do is generate an output file based on information from a text file, To executed in pashua_run ore add the pashua_run around the window argument: count=1 while read -r i do echo "AB${count}.type = openbrowser" echo "AB${count}.label = Choose a master playlist file" echo "AB${count}.width=310" echo "AB${count}.tooltip = Blabla filesystem browser" echo "some text with a line from the file: $i" (( count++ )) done < TEST.txt >> long.txt SO the output is AB1.type = openbrowser AB1.label = Choose a master playlist file AB1.width=310 AB1.tooltip = Blabla filesystem browser some text with a line from the file: foo AB2.type = openbrowser AB2.label = Choose a master playlist file AB2.width=310 AB2.tooltip = Blabla filesystem browser some text with a line from the file: bar AB3.type = openbrowser AB3.label = Choose a master playlist file AB3.width=310 AB3.tooltip = Blabla filesystem browser some text with a line from the file: dev AB4.type = openbrowser AB4.label = Choose a master playlist file AB4.width=310 AB4.tooltip = Blabla filesystem random So if there is a clever way to get the output of that and place it into pashua run would be cool, on the fly: I.E load te contents of TEST.txt and generate the place it into pashua_run, I've tried using cat and opening the file... but because it's in Pashua_run it doesn't work, is there a smart way to break out then back in? Or the second way which I was thinking, was create get the output then append it into the middle text file containing the pashua runtime, then execute it, maybe slightly hacky, but I would imagine it will do the job. Any ideas? ++ I know I probably could make my life a lot easier, by doing this in actionscript and cocoa, although at present don't have time for such a learning curve, although I do plan to get round to it.

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• [Android] For-Loop Performance Oddity

  - by Jack Holt

  I just noticed something concerning for-loop performance that seems to fly in the face of the recommendations given by the Google Android team. Look at the following code: package com.jackcholt; import android.app.Activity; import android.os.Bundle; import android.util.Log; public class Main extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); loopTest(); finish(); } private void loopTest() { final long loopCount = 1228800; final int[] image = new int[8 * 320 * 480]; long start = System.currentTimeMillis(); for (int i = 0; i < (8 * 320 * 480); i++) { image[i] = i; } for (int i = 0; i < (8 * 320 * 480); i++) { image[i] = i; } Log.i("loopTest", "Elapsed time (recompute loop limit): " + (System.currentTimeMillis() - start)); start = System.currentTimeMillis(); for (int i = 0; i < 1228800; i++) { image[i] = i; } for (int i = 0; i < 1228800; i++) { image[i] = i; } Log.i("loopTest", "Elapsed time (literal loop limit): " + (System.currentTimeMillis() - start)); start = System.currentTimeMillis(); for (int i = 0; i < loopCount; i++) { image[i] = i; } for (int i = 0; i < loopCount; i++) { image[i] = i; } Log.i("loopTest", "Elapsed time (precompute loop limit): " + (System.currentTimeMillis() - start)); } } When I run this code I get the following output in logcat: I/loopTest( 726): Elapsed time (recompute loop limit): 759 I/loopTest( 726): Elapsed time (literal loop limit): 755 I/loopTest( 726): Elapsed time (precompute loop limit): 1317 As you can see the code that seems to recompute the loop limit value on every iteration of the loop compares very well to the code that uses a literal value for the loop limit. However, the code that uses a variable which contains the precomputed value for the loop limit is significantly slower than either of the others. I'm not surprised that accessing a variable should be slower that using a literal but why does code that looks like it should be using two multiply instructions on every iteration of the loop so comparable in performance to a literal? Could it be that because literals are the only thing being multiplied, the Java compiler is optimizing out the multiplication and using a precomputed literal?

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• Data aggregation mongodb vs mysql

  - by Dimitris Stefanidis

  I am currently researching on a backend to use for a project with demanding data aggregation requirements. The main project requirements are the following. Store millions of records for each user. Users might have more than 1 million entries per year so even with 100 users we are talking about 100 million entries per year. Data aggregation on those entries must be performed on the fly. The users need to be able to filter on the entries by a ton of available filters and then present summaries (totals , averages e.t.c) and graphs on the results. Obviously I cannot precalculate any of the aggregation results because the filter combinations (and thus the result sets) are huge. Users are going to have access on their own data only but it would be nice if anonymous stats could be calculated for all the data. The data is going to be most of the time in batch. e.g the user will upload the data every day and it could like 3000 records. In some later version there could be automated programs that upload every few minutes in smaller batches of 100 items for example. I made a simple test of creating a table with 1 million rows and performing a simple sum of 1 column both in mongodb and in mysql and the performance difference was huge. I do not remember the exact numbers but it was something like mysql = 200ms , mongodb = 20 sec. I have also made the test with couchdb and had much worse results. What seems promising speed wise is cassandra which I was very enthusiastic about when I first discovered it. However the documentation is scarce and I haven't found any solid examples on how to perform sums and other aggregate functions on the data. Is that possible ? As it seems from my test (Maybe I have done something wrong) with the current performance its impossible to use mongodb for such a project although the automated sharding functionality seems like a perfect fit for it. Does anybody have experience with data aggregation in mongodb or have any insights that might be of help for the implementation of the project ? Thanks, Dimitris

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• Debugging site written mainly in JScript with AJAX code injection

  - by blumidoo

  Hello, I have a legacy code to maintain and while trying to understand the logic behind the code, I have run into lots of annoying issues. The application is written mainly in Java Script, with extensive usage of jQuery + different plugins, especially Accordion. It creates a wizard-like flow, where client code for the next step is downloaded in the background by injecting a result of a remote AJAX request. It also uses callbacks a lot and pretty complicated "by convention" programming style (lots of events handlers are created on the fly based on certain object names - e.g. current page name, current step name). Adding to that, the code is very messy and there is no obvious inner structure - the functions are scattered in the code, file names do not reflect the business role of the code, lots of functions and code snippets are most likely not used at all etc. PROBLEM: How to approach this code base, so that the inner flow of the code can be sort-of "reverse engineered" using a suite of smart debugging tools. Ideally, I would like to be able to attach to the running application and step through the code, breaking on each new function call. Also, it would be nice to be able to create a "diagram of calls" in the application (i.e. in order to run a particular page logic, this particular flow of function calls was executed in a particular order). Not to mention to be able to run a coverage analysis, identifying potentially orphaned code fragments. I would like to stress out once more, that it is impossible to understand the inner logic of the application just by looking at the code itself, unless you have LOTS of spare time and beer crates, which I unfortunately do not have :/ (shame...) An IDE of some sort that would aid in extending that code would be also great, but I am currently looking into possibility to use Visual Studio 2010 to do the job, as the site itself is a mix of Classic ASP and ASP.NET (I'd say - 70% Java Script with jQuery, 30% ASP). I have obviously tried FireBug, but I was unable to find a way to define a breakpoint or step into the code, which is "injected" into the client JS using AJAX calls (i.e. the application retrieves the code by invoking an URL and injects it to the client local code). Venkman debugger had similar issues. Any hints would be welcome. Feel free to ask additional questions.

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• Reporting Services as PDF through WebRequest in C# 3.5 "Not Supported File Type"

  - by Heath Allison

  I've inherited a legacy application that is supposed to grab an on the fly pdf from a reporting services server. Everything works fine up until the point where you try to open the pdf being returned and adobe acrobat tells you: Adobe Reader could not open 'thisStoopidReport'.pdf' because it is either not a supported file type or because the file has been damaged(for example, it was sent as an email attachment and wasn't correctly decoded). I've done some initial troubleshooting on this. If I replace the url in the WebRequest.Create() call with a valid pdf file on my local machine ie: @"C:temp/validpdf.pdf") then I get a valid PDF. The report itself seems to work fine. If I manually type the URL to the reporting services report that should generate the pdf file I am prompted for user authentication. But after supplying it I get a valid pdf file. I've replace the actual url,username,userpass and domain strings in the code below with bogus values for obvious reasons. WebRequest request = WebRequest.Create(@"http://x.x.x.x/reportServer?/reports/reportNam&rs:format=pdf&rs:command=render&rc:parameters=blahblahblah"); int totalSize = 0; request.Credentials = new NetworkCredential("validUser", "validPass", "validDomain"); request.Timeout = 360000; // 6 minutes in milliseconds. request.Method = WebRequestMethods.Http.Post; request.ContentLength = 0; WebResponse response = request.GetResponse(); Response.Clear(); BinaryReader reader = new BinaryReader(response.GetResponseStream()); Byte[] buffer = new byte[2048]; int count = reader.Read(buffer, 0, 2048); while (count > 0) { totalSize += count; Response.OutputStream.Write(buffer, 0, count); count = reader.Read(buffer, 0, 2048); } Response.ContentType = "application/pdf"; Response.Cache.SetCacheability(HttpCacheability.Private); Response.CacheControl = "private"; Response.Expires = 30; Response.AddHeader("Content-Disposition", "attachment; filename=thisStoopidReport.pdf"); Response.AddHeader("Content-Length", totalSize.ToString()); reader.Close(); Response.Flush(); Response.End();

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• WPF Storyboard works well, except for the first time it runs. Why?

  - by sofri

  Hi, I'm doing a Surface Application. And there I have something like a bulletin board where little cards with news on it are pinned on. On click they shall fly out of the board and scale bigger. My storyboard works well, except for the first time it runs. It's not a smooth animation then but it scales to its final size immediately and it's the same with the orientation-property. Just the center-property seems to behave correctly. This is an example for one of my Storyboards doing that: Storyboard stb = new Storyboard(); PointAnimation moveCenter = new PointAnimation(); DoubleAnimationUsingKeyFrames changeWidth = new DoubleAnimationUsingKeyFrames(); DoubleAnimationUsingKeyFrames changeHeight = new DoubleAnimationUsingKeyFrames(); DoubleAnimationUsingKeyFrames changeOrientation = new DoubleAnimationUsingKeyFrames(); moveCenter.From = News1.ActualCenter; moveCenter.To = new Point(250, 400); moveCenter.Duration = new Duration(TimeSpan.FromSeconds(1.0)); moveCenter.FillBehavior = FillBehavior.Stop; stb.Children.Add(moveCenter); Storyboard.SetTarget(moveCenter, News1); Storyboard.SetTargetProperty(moveCenter, new PropertyPath(ScatterViewItem.CenterProperty)); changeWidth.Duration = TimeSpan.FromSeconds(1); changeWidth.KeyFrames.Add(new EasingDoubleKeyFrame(266, KeyTime.FromTimeSpan(new System.TimeSpan(0, 0, 1)))); changeWidth.FillBehavior = FillBehavior.Stop; stb.Children.Add(changeWidth); Storyboard.SetTarget(changeWidth, News1); Storyboard.SetTargetProperty(changeWidth, new PropertyPath(FrameworkElement.WidthProperty)); changeHeight.Duration = TimeSpan.FromSeconds(1); changeHeight.KeyFrames.Add(new EasingDoubleKeyFrame(400, KeyTime.FromTimeSpan(new System.TimeSpan(0, 0, 1)))); changeHeight.FillBehavior = FillBehavior.Stop; stb.Children.Add(changeHeight); Storyboard.SetTarget(changeHeight, News1); Storyboard.SetTargetProperty(changeHeight, new PropertyPath(FrameworkElement.HeightProperty)); changeOrientation.Duration = TimeSpan.FromSeconds(1); changeOrientation.KeyFrames.Add(new EasingDoubleKeyFrame(0, KeyTime.FromTimeSpan(new System.TimeSpan(0, 0, 1)))); changeOrientation.FillBehavior = FillBehavior.Stop; stb.Children.Add(changeOrientation); Storyboard.SetTarget(changeOrientation, News1); Storyboard.SetTargetProperty(changeOrientation, new PropertyPath(ScatterViewItem.OrientationProperty)); stb.Begin(this); News1.Center = new Point(250, 400); News1.Orientation = 0; News1.Width = 266; News1.Height = 400; Pin1.Visibility = Visibility.Collapsed; news1IsOutside = true; Scroll1.IsEnabled = true; What's wrong with it?

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• Dynamic Data Manipulation using XSLT from XML

  - by Imrul

  I am not working with XSLT not too long. I read that variable of XSLT can't be updated on the fly, so how can i do the following task. I want to sum up Purchase & Sales and put them into a variable, and make some decision according to these values. (For example, if Purchase is greater then sales then do something if not, do something else) <rows> <row> <col attr2="Purchase" >100.00</col> <col attr2="Sales" >100.00</col> </row> <row > <col attr2="Purchase" >19.16</col> <col attr2="Sales" >12.94</col> </row> <row > <col attr2="Purchase" >0.67</col> <col attr2="Sales" >2.74</col> </row> <row > <col attr2="Purchase" >71.95</col> <col attr2="Sales" >61.54</col> </row> <row > <col attr2="Purchase" >3.62</col> <col attr2="Sales" >14.72</col> </row> <row > <col attr2="Purchase">8.80</col> <col attr2="Sales">1.22</col> </row> <row > <col attr2="Purchase" >-4.28</col> <col attr2="Sales" >6.53</col> </row> </rows> if anyone knows, please help me.

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• Accessing different connection strings at runtime in ASP.NET MVC 1

  - by Neil T.

  I'm trying to implement integration testing in my ASP.NET MVC 1.0 solution. The technologies in use are LINQ-to-SQL, NUnit and WatiN. I recently discovered a pattern that will allow me to create a testing version of the database on the fly without modifying the development version of the database. I needed this behavior in order to run my user interface tests in WatiN that may modify the database. The plan is to modify the connection string in the Web.config file, and pass that new connection string to the DataContext constructor. This way, I don't have to add routes or modify my URLs in order to perform the integration testing. I've set up the project so that the test setup can modify the connection string to point to the test database when the tests are running. The connection string is stored in web.config. The problem I'm having is that when I try to run the tests, I get a NullReferenceException when trying to access the HTTPContext. From everything that I have read so far, the HTTPContext is only available within the context of a controller. Here is the code for the property that is supposed to give me the reference to the Web.config file: private System.Configuration.Configuration WebConfig { get { ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap(); // NullReferenceException occurs on this line. fileMap.ExeConfigFilename = HttpContext.Current.Server.MapPath("~\\web.config"); System.Configuration.Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None); return config; } } Is there something that I am missing in order to make this work? Is there a better way to accomplish what I'm trying to achieve? UPDATE: I decided to abandon the modification of Web.config in lieu of a "request-scoped DataContext" pattern that I found here. From the looks of it, I believe it should give me the results I'm looking for. However, during the TextFixtureSetUp, I try to create a new copy of the database for testing purposes, and it fails silently. When I get to the tests, the repository still uses the production database connection string to load data.

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• Do you feel underappreciated or resent the geek/nerd stigma?

  - by dotnetdev

  At work we have a piece of A4 paper with the number of everyone in the office. The structure of this document is laid out in rectangles, by department. I work for the department that does all the technical stuff. That includes support—bear in mind that the support staff isn't educated in IT but just has experience in PC maintenance and providing support to a system we resell but don't have source code access to, project manager, team leader, a network administrator, a product manager, and me, a programmer. Anyway, on this paper, we are labelled as nerds and geeks. I did take a little offence to this, as much as it is light hearted (but annoying and old) humour. I have a vivid image that a geek is someone who doesn't go out but codes all day. I code all day at home and at work (when I have something to code...), but I keep balance by going out. I don't know why it is only people who work with computers that get such a stigma. No other profession really gets the same stigma—skilled, technical, or whatever. An account manager (and this is hardly a skilled job) says, "Perhaps [MY NAME HERE] could write some geeky code tomorrow to add this functionality to the website." It is funny how I get such an unfair stigma but I am so pivotal. In fact, if it wasn't for me, the company would have nothing to sell so the account managers would be redundant! I make systems, they get sold, and this is what pays the wages. It's funny how the account managers get a commission for how many systems they sell, or manage to make clients resubscribe to. Yet I built the thing in the first place! On top of that, my brother says all I do is type stuff on a keyboard all day. Surely if I did, I'd be typing at my normal typing speed of 100wpm+ as if I am writing a blog entry. Instead, I plan as I code along on the fly if commercial pressures and time prohibit proper planning. I never type as if I'm writing normal English. There is more to our jobs than just typing code. And my brother is a pipe fitter with no formal qualifications in his name. I could easily, and perhaps more justifiably, say he just manipulates a spanner or something. Does you feel underappreciated or that a geek/nerd stigma is undeserved or unfair?

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• Keeping track of business rules within IT department?

  - by evaldas-alexander

  I am looking for the best way to keep track of the business rules for both developers and everybody else (support staff / management) in a startup enviroment. The challenge is that our business model requires quite a lot of different business rules, which are created pretty much on the fly and evolving organically after that. After running this project for 3+ years, we have so many of such rules that often the only way to be sure about what the application is supposed to do in a certain situation is to go find the module responsible for that process and analyze its code and comments. That is all fine as long as you have one single developer who created the entire application from the scratch, but every new developer needs to go over pretty much entire codebase in order to understand how the application works. Even bigger problem is that non technical employees don't even have that option and therefore are forced to ask me pretty much every day how some certain case would be handled by the application. Quick example - we only start charging for our customer campaigns once they have been active for at least 72 hours, but at the same time we stop creating invoices for campaigns that belong to insolvent accounts and close such accounts within a month of the first failed charge. That does not apply to accounts that are set to "non-chargeable" which most commonly belongs to us since we are using the service ourselves. The invoices are created on the 1st of each month and include charges from the previous month + any current balance that the account might have. However, some customers are charged only 4 days after their invoice has been generated due to issues with their billing department. In addition to that, invoices are also created when customer deactivates his campaign, but that can only be done once the campaign is not longer under mandatory 6 month contract, unless account manager approves early deactivation. I know, that's quite a lot of rules that need to be taken into account when answering a question "when do we bill our customers", but actually I could still append an asterisk at the end of each sentence in order to disclose some rare exceptions. Of course, it would be easiest just to keep the business rules to the minimum, but we need to adapt to changing marketplace - i.e. less than a year ago we had no contracts whatsoever. One idea that I had so far was a simplistic wiki with categories corresponding to areas such as "Account activation", "Invoicing", "Collection procedures" and so on. Another idea would be to have giant interactive flowchart showing the entire customer "life cycle" from prospecting to account deactivation. What are your experiences / suggestions?

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• The Math of a Jump in a 2D game.

  - by ONi

  I have been all around with this question and I can't find the correct answer! So, behold, the description of my question: I'm working in J2ME, I have my gameloop that do the following: public void run() { Graphics g = this.getGraphics(); while (running) { long diff = System.currentTimeMillis() - lastLoop; lastLoop = System.currentTimeMillis(); input(); this.level.doLogic(); render(g, diff); try { Thread.sleep(10); } catch (InterruptedException e) { stop(e); } } } so it's just a basic gameloop, the doLogic() function calls for all the logic functions of the characters in the scene and render(g, diff) calls the animateChar function of every character on scene, following this, the animChar function in the Character class sets up everything in the screen as this: protected void animChar(long diff) { this.checkGravity(); this.move((int) ((diff * this.dx) / 1000), (int) ((diff * this.dy) / 1000)); if (this.acumFrame > this.framerate) { this.nextFrame(); this.acumFrame = 0; } else { this.acumFrame += diff; } } This ensures me that everything must to move according to the time that the machine takes to go from cycle to cycle (remember it's a phone, not a gaming rig). I'm sure it's not the most efficient way to achieve this behavior so I'm totally open for criticism of my programming skills in the comments, but here my problem: When I make I character jump, what I do is that I put his dy to a negative value, say -200 and I set the boolean jumping to true, that makes the character go up, and then I have this function called checkGravity() that ensure that everything that goes up has to go down, checkGravity also checks for the character being over platforms so I will strip it down a little for the sake of your time: public void checkGravity() { if (this.jumping) { this.jumpSpeed += 10; if (this.jumpSpeed > 0) { this.jumping = false; this.falling = true; } this.dy = this.jumpSpeed; } if (this.falling) { this.jumpSpeed += 10; if (this.jumpSpeed > 200) this.jumpSpeed = 200; this.dy = this.jumpSpeed; if (this.collidesWithPlatform()) { this.falling = false; this.standing = true; this.jumping = false; this.jumpSpeed = 0; this.dy = this.jumpSpeed; } } } So, the problem is, that this function updates the dy regardless of the diff, making the characters fly like Superman in slow machines, and I have no idea how to implement the diff factor so that when a character is jumping, his speed decrement in a proportional way to the game speed. Can anyone help me fix this issue? or give me pointers on how to make a 2D Jump in J2ME the right way. Thank you very much for your time.

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