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• Getting camera preview data without using a preview callback

  - by velocipedestrian

  I have an app that does some processing to camera preview frames before displaying them to the user. I'm currently using preview callbacks to access the image data, but the problem I have is that the onPreviewFrame() function stops getting called if you start recording video using a MediaRecorder, and I want the processing to continue when video is being recorded. I've tried doing the following: public static Bitmap convertViewToBitmap(View view) { Bitmap bitmap = Bitmap.createBitmap(view.getWidth(),view.getHeight(), Bitmap.Config.ARGB_8888); view.draw(new Canvas(bitmap)); return bitmap; } to convert the preview surface to a bitmap, but when I pass the preview SurfaceView to the function it returns an all-black bitmap (it works when I test it on normal views though). Is there any other way I can access the image data if preview callbacks are not available?

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• Combining FileStream and MemoryStream to avoid disk accesses/paging while receiving gigabytes of data?

  - by w128

  I'm receiving a file as a stream of byte[] data packets (total size isn't known in advance) that I need to store somewhere before processing it immediately after it's been received (I can't do the processing on the fly). Total received file size can vary from as small as 10 KB to over 4 GB. One option for storing the received data is to use a MemoryStream, i.e. a sequence of MemoryStream.Write(bufferReceived, 0, count) calls to store the received packets. This is very simple, but obviously will result in out of memory exception for large files. An alternative option is to use a FileStream, i.e. FileStream.Write(bufferReceived, 0, count). This way, no out of memory exceptions will occur, but what I'm unsure about is bad performance due to disk writes (which I don't want to occur as long as plenty of memory is still available) - I'd like to avoid disk access as much as possible, but I don't know of a way to control this. I did some testing and most of the time, there seems to be little performance difference between say 10 000 consecutive calls of MemoryStream.Write() vs FileStream.Write(), but a lot seems to depend on buffer size and the total amount of data in question (i.e the number of writes). Obviously, MemoryStream size reallocation is also a factor. Does it make sense to use a combination of MemoryStream and FileStream, i.e. write to memory stream by default, but once the total amount of data received is over e.g. 500 MB, write it to FileStream; then, read in chunks from both streams for processing the received data (first process 500 MB from the MemoryStream, dispose it, then read from FileStream)? Another solution is to use a custom memory stream implementation that doesn't require continuous address space for internal array allocation (i.e. a linked list of memory streams); this way, at least on 64-bit environments, out of memory exceptions should no longer be an issue. Con: extra work, more room for mistakes. So how do FileStream vs MemoryStream read/writes behave in terms of disk access and memory caching, i.e. data size/performance balance. I would expect that as long as enough RAM is available, FileStream would internally read/write from memory (cache) anyway, and virtual memory would take care of the rest. But I don't know how often FileStream will explicitly access a disk when being written to. Any help would be appreciated.

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• What happens to a transaction when App Pool recycles or the worker process is terminated forcefully?

  - by ARS

  The architecture of the application is straight forward. There is a web application which maintain account holder data. This data is processed and the status of account holders is updated based on number of business rules. This process is initiated using a button on the page and is a long running process (say 15 mins). A component is developed to do this data processing which internally calls stored procedures. Most of the business rules are kept in stored procedure. To handle timeouts the processing is done asynchornously(using Thread Pool or custom thread or Async Callback Delegates). The entire process run under a transaction. I would like to know your view on what happens to the transaction if the app pool is recycled or the worker process is terminated forcefully?

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• NServicebus delay message saga?

  - by user170469

  How can I delay processing a saga message in NServicebus for 24 hours?

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• Sleep a thread until an event is attended in another thread from a different class

  - by Afro Genius

  I have an application that fires 2 threads, the 1st launches another class to do some processing which in turn launches a 3rd class to do yet more processing. The 2nd thread in the main class should wait until some event in the 3rd class completes before it performs its job. How can this be achieved? I had tried implementing a wait/notify to share a lock object between the two threads but technically this will not work as I found the hard way. Can I share a lock between classes? Note, an instance of the 3rd class is declared in the 1st class and passed as parameter to the 2nd class. Also I tried creating boolean value in 3rd class that tells when event is complete then poll 2nd thread till this value is true. This worked but is not very desirable. Also is actionListner a better approach to this problem?

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• Is there a work-around that allows missing data to equal NULL for LOAD DATA INFILE in MySQL?

  - by richardh

  I have a lot of large csv files with NULL values stored as ,, (i.e., no entry). After a lot of searching I found that this is a known "bug", although it may be a feature for some users. Is there a way that I can fix this on the fly without pre-processing? These data are all numeric, so a zero value is very different from NULL. Or if I have to do pre-processing, is there one that is most promising for dealing with tens of csv files of 100mb to 1gb? Thanks!

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• Looking for suggestions about an architecture of a MultiThreaded app.

  - by Dimitri

  Hello everyone. I am looking to develop a multithreaded application that will be running in unconditional loop and processing high volume of data. High volume is 2000+ records per minute. Processing will involve data retrieval, calculations and data updates. I need the application to perform so that there is virtually no back log, meaning i need to be able to finish up all of the 2000 points in one minute or even faster. Our current implementation features a multithreaded application that is spawn multiple times (from 10 to 20) and we are noticing that it's not handling data as expected and i even feel that instances of the application compete with each other for processor time and eventually if not slowing, not benefiting each other for sure. I would like to know what would be the best approach: have a single instance running but maximize threads that can run simultaneously? or is there other ways i don't know? I'm open to suggestions. Thank you in advance

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• Ajax progress with PHP session

  - by FFish

  I have an app that processes images and use jQuery to display progress to the user. I done this with writing to a textfile each time and image is processed and than read this status with a setInterval. Because no images are actually written in the processing (I do it in PHP's memory) I thought a log.txt would be a solution, but I am not sure about all the fopen and fread's. Is this prone to issues? I tried also with PHP sessions, but can't seem to get it to work, I don't get why.. HTML: <a class="download" href="#">request download</a> <p class="message"></p> JS: $('a.download').click(function() { var queryData = {images : ["001.jpg", "002.jpg", "003.jpg"]}; $("p.message").html("initializing..."); var progressCheck = function() { $.get("dynamic-session-progress.php", function(data) { $("p.message").html(data); } ); }; $.post('dynamic-session-process.php', queryData, function(intvalId) { return function(data) { $("p.message").html(data); clearInterval(intvalId); } } (setInterval(progressCheck, 1000)) ); return false; }); process.php: // session_start(); $arr = $_POST['images']; $arr_cnt = count($arr); $filename = "log.txt"; for ($i = 1; $i <= $arr_cnt; $i++) { $content = "processing $val ($i/$arr_cnt)"; $handle = fopen($filename, 'w'); fwrite($handle, $content); fclose($handle); // $_SESSION['counter'] = $content; sleep(3); // to mimic image processing } echo "<a href='#'>download zip</a>"; progress.php: // session_start(); $filename = "log.txt"; $handle = fopen($filename, "r"); $contents = fread($handle, filesize($filename)); fclose($handle); echo $contents; // echo $_SESSION['counter'];

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• Webhook data for Orders Paid

  - by David Lazar

  A client recently requested some fancy processing based off of the Gateway attribute registered with a Paid order. When I receive, validate and inspect the JSON of the order, I am logging the gateway attribute and finding it is nil at times. When I check the order using the API after the Webhook, the gateway attribute is present and matches the one rendered in the Shop admin. Is there an explanation for why the gateway can at times be nil? This prevents me from taking care of the client's requested processing.

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• Fast way to pass a simple java object from one thread to another

  - by Adal

  I have a callback which receives an object. I make a copy of this object, and I must pass it on to another thread for further processing. It's very important for the callback to return as fast as possible. Ideally, the callback will write the copy to some sort of lock-free container. I only have the callback called from a single thread and one processing thread. I only need to pass a bunch of doubles to the other thread, and I know the maximum number of doubles (around 40). Any ideas? I'm not very familiar with Java, so I don't know the usual ways to pass stuff between threads.

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• How do I know if a boost thread is done ?

  - by jules

  I am using boost::thread to process messages in a queue. When a first message comes I start a message processing thread. When a second message comes I check if the message processing thread is done. if it is done I start a new one if it is not done I don nothing. How do I know if the thread is done ? I tried with joinable() but it is not working, as when the thread is done, it is still joinable. I also tried to interrupt the process at once, and add an interruption point at the end of my thread, but it did not work. Thanks

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• Cannot bind to list<T>.property or list<T>.item.property in details section of Telerik report

  - by fluf

  I have created a Telerik report and I am setting the datasource on runtime to an object with some properties and a List. I am using the properties in the page and report header sections and i want to use the list as the details. Now the problem is binding to the List's item properties in the details section. I have played around with the expression builder and it seems that i should access the properties like this : [=Fields.myList.Item.myProperty] when i run the program i get a nice big red rectangle with the following error : An error has occured while processing TextBox 'textBox28':Common Language Runtime detected an invalid program. I have tried to change different variants of expression which also gives me other errors [=Fields.myList.myPropery] An error has occured while processing TextBox 'textBox28': The expression contains object 'myProperty' that is not defined in the current context. The closest i have gotton was with the object it self, which outputs the object.toString() [=Fields.myList]

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• Performance: float to int cast and clippling result to range

  - by durandai

  I'm doing some audio processing with float. The result needs to be converted back to PCM samples, and I noticed that the cast from float to int is surprisingly expensive. Whats furthermore frustrating that I need to clip the result to the range of a short (-32768 to 32767). While I would normally instictively assume that this could be assured by simply casting float to short, this fails miserably in Java, since on the bytecode level it results in F2I followed by I2S. So instead of a simple: int sample = (short) flotVal; I needed to resort to this ugly sequence: int sample = (int) floatVal; if (sample > 32767) { sample = 32767; } else if (sample < -32768) { sample = -32768; } Is there a faster way to do this? (about ~6% of the total runtime seems to be spent on casting, while 6% seem to be not that much at first glance, its astounding when I consider that the processing part involves a good chunk of matrix multiplications and IDCT)

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• Profiling and Graphics.updateDisplay0()

  - by AD

  I am profiling my BlackBerry application (a game) with the options 'In method only' and 'Time including native method'. Under the 'All methods' node (after a decent run of the game) the single most time consuming function is Graphics.updateDisplay0() with over 50% of the run time spent there. I don't quite know what is the purpose of that function or if I can do anything to reduce its processing time, so if anyone can shed some light on the matter, I would be grateful. Because from what I understand with the 'In method only' option, it means there is some processing within that function. ps. there is no information on that function in the documentation.

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• In forms application, is there any Alternative to MsgBox?

  - by GuruC

  I like how MsgBox stops all further processing until it's clicked but I don't like how it pops that little msgbox in the middle of the screen, which I then have bring to the front if there is a window covering it. Is there a way to do something like a msgbox but keep it on my Form (which is always in view) so I can go ahead and click a button on the form instead of having to bring the little msgbox window on top of windows that may be covering it. I use the msgbox to inform me that a certain situation has happened, which I manually fix and when I'm done I click the MsgBox to continue processing. It'd be nice to have this button right on the form.

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• Is there anything wrong with having a few private methods exposing IQueryable<T> and all public meth

  - by Nate Bross

  I'm wondering if there is a better way to approach this problem. The objective is to reuse code. Let’s say that I have a Linq-To-SQL datacontext and I've written a "repository style" class that wraps up a lot of the methods I need and exposes IQueryables. (so far, no problem). Now, I'm building a service layer to sit on top of this repository, many of the service methods will be 1<-1 with repository methods, but some will not. I think a code sample will illustrate this better than words. public class ServiceLayer { MyClassDataContext context; IMyRepository rpo; public ServiceLayer(MyClassDataContext ctx) { context = ctx; rpo = new MyRepository(context); } private IQueryable<MyClass> ReadAllMyClass() { // pretend there is some complex business logic here // and maybe some filtering of the current users access to "all" // that I don't want to repeat in all of the public methods that access // MyClass objects. return rpo.ReadAllMyClass(); } public IEnumerable<MyClass> GetAllMyClass() { // call private IQueryable so we can do attional "in-database" processing return this.ReadAllMyClass(); } public IEnumerable<MyClass> GetActiveMyClass() { // call private IQueryable so we can do attional "in-database" processing // in this case a .Where() clause return this.ReadAllMyClass().Where(mc => mc.IsActive.Equals(true)); } #region "Something my class MAY need to do in the future" private IQueryable<MyOtherTable> ReadAllMyOtherTable() { // there could be additional constrains which define // "all" for the current user return context.MyOtherTable; } public IEnumerable<MyOtherTable> GetAllMyOtherTable() { return this.ReadAllMyOtherTable(); } public IEnumerable<MyOtherTable> GetInactiveOtherTable() { return this.ReadAllMyOtherTable.Where(ot => ot.IsActive.Equals(false)); } #endregion } This particular case is not the best illustration, since I could just call the repository directly in the GetActiveMyClass method, but let’s presume that my private IQueryable does some extra processing and business logic that I don't want to replicate in both of my public methods. Is that a bad way to attack an issue like this? I don't see it being so complex that it really warrants building a third class to sit between the repository and the service class, but I'd like to get your thoughts. For the sake of argument, lets presume two additional things. This service is going to be exposed through WCF and that each of these public IEnumerable methods will be calling a .Select(m => m.ToViewModel()) on each returned collection which will convert it to a POCO for serialization. The service will eventually need to expose some context.SomeOtherTable which wont be wrapped into the repository.

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• ANY material writen in/for DELPHI around the graphics topic?

  - by José Eduardo

  Does anyone knows ANY material writen in/for DELPHI around the graphics topic? Planning to build a software for medical imaging processing . Thinking in 3D UI to absorve the power of nvidias GTX graphics card, and some real-time 2D processing integrated with high-end scanners. Please dont take this as a "rant" but, we have zillions of C++ books writen about that kind of topic and nothing for pascal/delphi. If you have some experience could you comment about that? Is it better to learn c++, to have access to that material? Can i go with delphi? I have experience with delphi, but none with graphics... And i have a deadline... Thanks.

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• How do I profile memory usage in my project

  - by Gacek

  Are there any good, free tools to profile memory usage in C# ? Details: I have a visualization project that uses quite large collections. I would like to check which parts of this project - on the data-processing side, or on the visualization side - use most of the memory, so I could optimize it. I know that when it comes to computing size of the collection the case is quite simple and I can do it on my own. But there are also certain elements for which I cannot estimate the memory usage so easily. The memory usage is quite big, for example processing a file of size 35 MB my program uses a little bit more than 250 MB of RAM.

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• php variable persistance

  - by Illes Peter

  I have two files: index.php /lib/user.php Index contains the form: <div class="<? echo $msgclass; ?>"> <? echo $msg; ?> </div> <form id="signin" action="/lib/user.php" method="post"> ... </form> User.php makes all the processing. It sets $msg to 'some error message' and $msgalert to 'error' in case of any error. At the end of processing it uses header() to redirect to index.php But after redirection $msg and $msgalert no longer persist and index only gets empty vars. How can i fix this?

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• What is Java Message Service (JMS) for?

  - by Daniel

  I am currently evaluating JMS and I don't get what I could use it for. Currently, I believe this would be a Usecase: I want to create a SalesInvoice PDF and print it when an SalesOrder leaves the Warehouse, so during the Delivery transaction I could send a transactional print request which just begins when the SalesOrder transaction completes successfully. Now I found out most JMS products are standalone server. Why would a need a Standalone Server for Message Processing, vs. e.g. some simple inproc processing with Quartz scheduler? How does it interact with my application? Isn't it much too slow? What are Usecases you already implemented successfully?

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• Applying transformations to NSBitmapImageRep

  - by Adam

  So ... I have an image loaded into an NSBitmapImageRep object, so I am able to examine the contents of specific pixels via a two dimensional array. Now I want to apply a couple of "transformations" to the image, in preparation for some additional processing. If I was manipulating the image manually, in Photoshop, I would: Rotate the image Crop a portion of it and discard the rest Apply a "threshold" transformation (which essentially converts the image to black and white, based on the threshold value I provide) Resample the image to shrink it down a bit (which, although losing some image quality, will speed up the subsequent processing) (not necessarily in that order) Are there objective C methods available to facilitate these specific image manipulations, with the data in the NSBitmapImageRep object? If so, can someone point me to some good examples?

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• How does Facebook codes their Cropping tool?

  - by Trip

  I ask this because I am currently trying to work out my own technique, and there are huge strategic hangups for the entire site when your begin this. Of them are: Using jCrop and rMagick, it takes up a huge amount of processing ( to which I have backgrounded ). Because I have it backgrounded, I must by ajax develop a feature that auto-updates every five seconds to check when the backgrounding is done. Has anyone accomplished this with their sites? If so, what are some creative techniques you came across to keep the processing streamline, and the users happy?

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• Best way to update UI from other classes?

  - by Jack

  I've got several nested classes, with the following structure: BackupLocation contains list of BackupClients BackupClients contains a list of BackupVersions BackupVersions contains a list of BackupFiles In my UI - Im populating a combo box with BackupLocations - and have several listboxes for the clients, versions, and files. When processing the BackupLocations - I can update my status bar easily because thats the top level class that the UI creates. But how can I update the status bar and progress bar on each file being processed? Since the BackupFiles are 3 levels deep, I cant see any way to update the UI. The actual processing of the files are within the BackupVersion class - which loads its files. I think it probably has something to do with events and delegates - but am unsure exactly how to proceed with this, any help would be appreciated.

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• Suspend TimerTask until the next execution

  - by user1052518

  I am using a TimerTask to run some periodic tasks, the task being processing a set of files. I have a requirement where if the number of files to be processed exceeds a pre-determined limit, the thread suspends execution and waits till the next cycle to start processing the files again. Is there a way to suspend the TimerTask until the next execution period or do I have to extend the TimerTask class to achieve this functionality? I saw there is a TimerTask.cancel method, but this will cancel all further executions of this thread. I don't want this to happen. I just want the thread to be suspended until the next execution period. I don't have the luxury of moving to any of the other concurrent classes in Java as our framework uses TimerTask, and I have to stick with it. Any suggestions, pointers or tips are greatly appreciated. thanks, Asha

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• can we do getwriter and forward in a single servlet

  - by karanits

  Lets say my form called a servlet. I would do some processing in it. In the servlet i want to print something on the page. for that i used PrintWriter out=response.getWriter(); out.println("some text here"); then further in the servlet i did some more form processing which works fine and after that i want the servlet to be forwarded to a jsp page. For this i used RequestDispatcher rd = request.getRequestDispatcher("/somepage.jsp"); rd.forward(request, response); the problem comes here. the text some text here gets printed, but the servlet doesn't forward request to the jsp page, as if the code doesn't run.

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