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  • What is the best way to test using grails using IDEA?

    - by egervari
    I am seriously having a very non-pleasant time testing using Grails. I will describe my experience, and I'd like to know if there's a better way. The first problem I have with testing is that Grails doesn't give immediate feedback to the developer when .save() fails inside of an integration test. So let's say you have a domain class with 12 fields, and 1 of them is violating a constraint and you don't know it when you create the instance... it just doesn't save. Naturally, the test code afterward is going to fail. This is most troublesome because the thingy under test is probably fine... and the real risk and pain is the setup code for the test itself. So, I've tried to develop the habit of using .save(failOnError: true) to avoid this problem, but that's not something that can be easily enforced by everyone working on the project... and it's kind of bloaty. It'd be nice to turn this on for code that is running as part of a unit test automatically. Integration Tests run slow. I cannot understand how 1 integration test that saves 1 object takes 15-20 seconds to run. With some careful test planning, I've been able to get 1000 tests talking to an actual database and doing dbunit dumps after every test to happen in about the same time! This is dumb. It is hard to run all the unit tests and not integration tests in IDEA. Integration tests are a massive pain. Idea actually shows a GREEN BAR when integration tests fail. The output given by grails indicates that something failed, but it doesn't say what it was. It says to look in the test reports... which forces the developer to launch up their file system to hunt the stupid html file down. What a pain. Then once you got the html file and click to the failing test, it'll tell you a line number. Since these reports are not in the IDE, you can't just click the stack trace to go to that line of code... you gotta go back and find it yourself. ARGGH!@!@! Maybe people put up with this, but I refuse. Testing should not be this painful. It should be fast and painless, or people won't do it. Please help. What is the solution? Rails instead of Grails? Something else entirely? I love the Grails framework, but they never demo their testing for a reason. They have a snazzy framework, but the testing is painful. After having used Scala for the last 1.5 months, and being totally spoiled by ScalaTest... I can't go back to this.

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  • Dynamically specify the type in C#

    - by Lirik
    I'm creating a custom DataSet and I'm under some constrains: I want the user to specify the type of the data which they want to store. I want to reduce type-casting because I think it will be VERY expensive. I will use the data VERY frequently in my application. I don't know what type of data will be stored in the DataSet, so my initial idea was to make it a List of objects, but I suspect that the frequent use of the data and the need to type-cast will be very expensive. The basic idea is this: class DataSet : IDataSet { private Dictionary<string, List<Object>> _data; /// <summary> /// Constructs the data set given the user-specified labels. /// </summary> /// <param name="labels"> /// The labels of each column in the data set. /// </param> public DataSet(List<string> labels) { _data = new Dictionary<string, List<object>>(); foreach (string label in labels) { _data.Add(label, new List<object>()); } } #region IDataSet Members public List<string> DataLabels { get { return _data.Keys.ToList(); } } public int Count { get { _data[_data.Keys[0]].Count; } } public List<object> GetValues(string label) { return _data[label]; } public object GetValue(string label, int index) { return _data[label][index]; } public void InsertValue(string label, object value) { _data[label].Insert(0, value); } public void AddValue(string label, object value) { _data[label].Add(value); } #endregion } A concrete example where the DataSet will be used is to store data obtained from a CSV file where the first column contains the labels. When the data is being loaded from the CSV file I'd like to specify the type rather than casting to object. The data could contain columns such as dates, numbers, strings, etc. Here is what it could look like: "Date","Song","Rating","AvgRating","User" "02/03/2010","Code Monkey",4.6,4.1,"joe" "05/27/2009","Code Monkey",1.2,4.5,"jill" The data will be used in a Machine Learning/Artificial Intelligence algorithm, so it is essential that I make the reading of data very fast. I want to eliminate type-casting as much as possible, since I can't afford to cast from 'object' to whatever data type is needed on every read. I've seen applications that allow the user to pick the specific data type for each item in the csv file, so I'm trying to make a similar solution where a different type can be specified for each column. I want to create a generic solution so I don't have to return a List<object> but a List<DateTime> (if it's a DateTime column) or List<double> (if it's a column of doubles). Is there any way that this can be achieved? Perhaps my approach is wrong, is there a better approach to this problem?

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  • Use QuickCheck by generating primes

    - by Dan
    Background For fun, I'm trying to write a property for quick-check that can test the basic idea behind cryptography with RSA. Choose two distinct primes, p and q. Let N = p*q e is some number relatively prime to (p-1)(q-1) (in practice, e is usually 3 for fast encoding) d is the modular inverse of e modulo (p-1)(q-1) For all x such that 1 < x < N, it is always true that (x^e)^d = x modulo N In other words, x is the "message", raising it to the eth power mod N is the act of "encoding" the message, and raising the encoded message to the dth power mod N is the act of "decoding" it. (The property is also trivially true for x = 1, a case which is its own encryption) Code Here are the methods I have coded up so far: import Test.QuickCheck -- modular exponentiation modExp :: Integral a => a -> a -> a -> a modExp y z n = modExp' (y `mod` n) z `mod` n where modExp' y z | z == 0 = 1 | even z = modExp (y*y) (z `div` 2) n | odd z = (modExp (y*y) (z `div` 2) n) * y -- relatively prime rPrime :: Integral a => a -> a -> Bool rPrime a b = gcd a b == 1 -- multiplicative inverse (modular) mInverse :: Integral a => a -> a -> a mInverse 1 _ = 1 mInverse x y = (n * y + 1) `div` x where n = x - mInverse (y `mod` x) x -- just a quick way to test for primality n `divides` x = x `mod` n == 0 primes = 2:filter isPrime [3..] isPrime x = null . filter (`divides` x) $ takeWhile (\y -> y*y <= x) primes -- the property prop_rsa (p,q,x) = isPrime p && isPrime q && p /= q && x > 1 && x < n && rPrime e t ==> x == (x `powModN` e) `powModN` d where e = 3 n = p*q t = (p-1)*(q-1) d = mInverse e t a `powModN` b = modExp a b n (Thanks, google and random blog, for the implementation of modular multiplicative inverse) Question The problem should be obvious: there are way too many conditions on the property to make it at all usable. Trying to invoke quickCheck prop_rsa in ghci made my terminal hang. So I've poked around the QuickCheck manual a bit, and it says: Properties may take the form forAll <generator> $ \<pattern> -> <property> How do I make a <generator> for prime numbers? Or with the other constraints, so that quickCheck doesn't have to sift through a bunch of failed conditions? Any other general advice (especially regarding QuickCheck) is welcome.

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  • ffmpeg add two audio streams to video

    - by Tossin Hausen
    I tried this: ffmpeg -i /sdcard/video/transcode/video.avi -map 0:0,0 -i /sdcard/video/transcode/first.mp3 -map 1:0,1 -i /sdcard/video/transcode/second.mp3 -map 2:0,2 -acodec copy -vcodec py /sdcard/video/transcode/Output.avi to add two audio streams to one video file. But ffmpeg says the number of mappings should match the number of output streams. What is wrong here? I'm trying to work with an Android build of FFmepg "ffmpeg for android beta". "Does not work" means that this uncommunicative Android build of FFmpeg just stops without giving any error message. The -codec copy option does not work with this build. Now I tried the same set of files with the FFmpeg called command line tool that comes with Ubuntu 10. Something (can't say where it is from). The -codec copy option does not work with this FFmpeg too. Here the complete output: m30x:~/movie/Film$ ffmpeg -i input.avi -i first.mp3 -i second.mp3 -map 0 -map 1 -map 2 -acodec copy -vcodec copy output.avi FFmpeg version SVN-r0.5.9-4:0.5.9-0ubuntu0.10.04.1, Copyright (c) 2000-2009 Fabrice Bellard, et al. configuration: --extra-version=4:0.5.9-0ubuntu0.10.04.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --disable-stripping --disable-vhook --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static libavutil 49.15. 0 / 49.15. 0 libavcodec 52.20. 1 / 52.20. 1 libavformat 52.31. 0 / 52.31. 0 libavdevice 52. 1. 0 / 52. 1. 0 libavfilter 0. 4. 0 / 0. 4. 0 libswscale 0. 7. 1 / 0. 7. 1 libpostproc 51. 2. 0 / 51. 2. 0 built on Jun 12 2012 16:27:34, gcc: 4.4.3 [NULL @ 0x93cfd10]looks like this file was encoded with (divx4/(old)xvid/opendivx) -> forcing low_delay flag Seems stream 0 codec frame rate differs from container frame rate: 30000.00 (30000/1) -> 25.00 (25/1) Input #0, avi, from 'input.avi': Duration: 01:30:33.00, start: 0.000000, bitrate: 901 kb/s Stream #0.0: Video: mpeg4, yuv420p, 576x432, 25 tbr, 25 tbn, 30k tbc Input #1, mp3, from 'first.mp3': Duration: 01:30:32.84, start: 0.000000, bitrate: 63 kb/s Stream #1.0: Audio: mp3, 22050 Hz, stereo, s16, 64 kb/s Input #2, mp3, from 'second.mp3': Duration: 01:30:32.84, start: 0.000000, bitrate: 63 kb/s Stream #2.0: Audio: mp3, 22050 Hz, stereo, s16, 64 kb/s Number of stream maps must match number of output streams Merging only one audio stream with the video stream works with Ubuntu and Android version of FFmpeg. Here the complete output: ffmpeg -i input.avi -i first.mp3 -map 0 -map 1 -acodec copy -vcodec copy output.avi FFmpeg version SVN-r0.5.9-4:0.5.9-0ubuntu0.10.04.1, Copyright (c) 2000-2009 Fabrice Bellard, et al. configuration: --extra-version=4:0.5.9-0ubuntu0.10.04.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --disable-stripping --disable-vhook --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static libavutil 49.15. 0 / 49.15. 0 libavcodec 52.20. 1 / 52.20. 1 libavformat 52.31. 0 / 52.31. 0 libavdevice 52. 1. 0 / 52. 1. 0 libavfilter 0. 4. 0 / 0. 4. 0 libswscale 0. 7. 1 / 0. 7. 1 libpostproc 51. 2. 0 / 51. 2. 0 built on Jun 12 2012 16:27:34, gcc: 4.4.3 [NULL @ 0x9bfad10]looks like this file was encoded with (divx4/(old)xvid/opendivx) -> forcing low_delay flag Seems stream 0 codec frame rate differs from container frame rate: 30000.00 (30000/1) -> 25.00 (25/1) Input #0, avi, from 'input.avi': Duration: 01:30:33.00, start: 0.000000, bitrate: 901 kb/s Stream #0.0: Video: mpeg4, yuv420p, 576x432, 25 tbr, 25 tbn, 30k tbc Input #1, mp3, from 'first.mp3': Duration: 01:30:32.84, start: 0.000000, bitrate: 63 kb/s Stream #1.0: Audio: mp3, 22050 Hz, stereo, s16, 64 kb/s Output #0, avi, to 'output.avi': Stream #0.0: Video: mpeg4, yuv420p, 576x432, q=2-31, 90k tbn, 25 tbc Stream #0.1: Audio: libmp3lame, 22050 Hz, stereo, s16, 64 kb/s Stream mapping: Stream #0.0 -> #0.0 Stream #1.0 -> #0.1 Press [q] to stop encoding frame= 6157 fps=6156 q=-1.0 size= 31667kB time=246.28 bitrate=1053.3kbits/s Do you have an idea why it does not work with two audio streams? By the way, ffmpeg -i input_with_first_audio_stream.avi -i second.mp3 -acodec copy -vcodec copy output_two_audio_streams.avi -newaudio works with both versions of ffmpeg that I use, but the first audio stream is played too fast (x10 or more), while the second audio stream is played correct. Many thanks in advance and sorry for my unconventional question and outdated versions of ffmpeg. But I am a lamer and it is not so easy for me to compile from the source (especially for the Android version). I will try to compile an up to date version of ffmpeg with Ubuntu, but I don't have much free time.

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  • Hide element if displayed (a little complex case)

    - by Ricardo
    Hello, I have a list of radio buttons that are inside a DIV called "radio-btns-wrapper-wjs", this DIV slides down/up when you click on a 'trigger' element, in my case a < span with the class "selected-search-wjs". The DIV "radio-btns-wrapper-wjs" slides back up when the user selects one of the radio buttons. This DIV also slides back up when the user does not take any action (does not select a radio button) but has already moved his mouse over "radio-btns-wrapper-wjs" DIV and then moves it out. So far, so good. What I need is to have the same DIV, "radio-btns-wrapper-wjs", slide back up when the user moves his mouse out from the < span "selected-search-wjs" element but NOT if the user moves his mouse over the DIV "radio-btns-wrapper-wjs". The thing is that is that if do this: $('.selected-search-wjs').mouseleave(function() { $('.radio-btns-wrapper-wjs').slideUp(); }); The DIV with the radio buttons, "radio-btns-wrapper-wjs", slides back up as soon as I leave that DIV to select a radio button. I need a condition that says something like: "Hide the DIV "radio-btns-wrapper-wjs" if the user hovers over you and then hovers out. Also, hide this same DIV if the user moves his mouse away from the < span "selected-search-wjs", but NOT if he moves his mouse over the DIV "radio-btns-wrapper-wjs"." Does all this make sense? Here's my HTML: <div class="radio-btns-wjs"><span class="selected-search-wjs">&nbsp;</span> <div class="radio-btns-wrapper-wjs"> <label> <input type="radio" name="rb" value="all" id="all"> All</label> <label> <input type="radio" name="rb" value="ln" id="ln"> Option 1</label> <label> <input type="radio" name="rb" value="prodsandserv" id="prodsandserv"> Option 2</label> <label> <input type="radio" name="rb" value="publications" id="publications"> Option 3</label> <label> <input type="radio" name="rb" value="comm" id="comm"> Option 4</label> <label> <input type="radio" name="rb" value="lweb" id="lweb"> Option 5</label> </div> </div> My jQuery: //This slides up/down the DIV with the radio buttons $('.selected-search').addClass('selected-search-wjs').removeClass('selected-search').append('Please Select&hellip;').click(function() { $('.radio-btns-wrapper-wjs').slideToggle('fast'); }); //This hides the DIV with the radio buttons, if the user has hovered over it $('.radio-btns-wrapper-wjs').mouseleave(function() { $(this).slideUp(); }); As you can see I'm very new to jQuery, but this is way over my head now. Any help is greatly appreciated. Here's a live example: http://jsfiddle.net/t2HkQ/3/ Thanks.

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  • CakeDC Users Plugin - I Can't Send Emails

    - by JimBadger
    I apologise for the rambling nature of this question, please bear with me and I'll provide all the extra info needed for you to stop me going mad from failing at something that looks inherently very straightforward... I've just installed CakePHP 2.2, and the first thing I've done is add the cakeDC Users plugin. It's all working, apart from sending an email verification when a user registers. I've tried so many combinations of different things in email.php, that I have now utterly got my knickers in a twist. Whatever I do, when the verification email should be sent, all I get is: No connection could be made because the target machine actively refused it. My email.php currently looks like this: class EmailConfig { public $default = array( 'transport' => 'Smtp', 'from' => '[email protected]', //'charset' => 'utf-8', //'headerCharset' => 'utf-8', ); public $smtp = array( 'transport' => 'Smtp', 'from' => array('Blah <[email protected]>' => 'Chimp'), 'host' => 'ssl://smtp.gmail.com', 'port' => 465, 'timeout' => 30, 'username' => '[email protected]', 'password' => 'secret', 'client' => null, 'log' => false, //'charset' => 'utf-8', //'headerCharset' => 'utf-8', ); public $fast = array( 'from' => '[email protected]', 'sender' => null, 'to' => null, 'cc' => null, 'bcc' => null, 'replyTo' => null, 'readReceipt' => null, 'returnPath' => null, 'messageId' => true, 'subject' => null, 'message' => null, 'headers' => null, 'viewRender' => null, 'template' => false, 'layout' => false, 'viewVars' => null, 'attachments' => null, 'emailFormat' => null, 'transport' => 'Smtp', 'host' => 'blah.net', 'port' => 25, 'timeout' => 30, 'username' => 'user', 'password' => 'secret', 'client' => null, 'log' => true, //'charset' => 'utf-8', //'headerCharset' => 'utf-8', ); } How do I get cakeDC Users plugin to just send a non-SMTP email? Or do I have to use, for example, my Gmail details? But, if I do have to go down the SMTP route, what is wrong with the above? Other info: I'm using the latest version of XAMPP and my PHP install is ssl enabled.

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  • Play Video File in Asp. Net 3.5 in IIS

    - by Sneha Joshi
    I have developed an application to upload a video on the server and then play it. It runs well when i execute it in Visual Studio 2008 in-built web server.. But when I configure it on IIS, the video does not play... Is there any settings needed in IIS to play video ?? The code of Button Click event - **protected void btnPlayVideo_Click(object sender, EventArgs e) { try { string himaSagarURL = this.lnkbtnVideo.Text; bool isFullSize = false; this.Literal1.Text = this.Play_Video(himaSagarURL, isFullSize); } catch (Exception ex) { this.Response.Write(ex.ToString()); } } This button click event calls the Play_Video method which is given below.. The code I used for embedding - private string Play_Video(string sagarURL, bool isFullSize) { string himaSagarObject = ""; sagarURL = sagarURL + ""; sagarURL = sagarURL.Trim(); if (sagarURL.Length > 0) { //Continue. } else { throw new System.ArgumentNullException("sagarURL"); } string himaSagarWidthAndHeight = ""; if (isFullSize) { himaSagarWidthAndHeight = ""; } else { himaSagarWidthAndHeight = "width='640' height='480'"; } himaSagarObject = himaSagarObject + "<object classid='CLSID:22D6F312-B0F6-11D0-94AB-0080C74C7E95' id='player' " + himaSagarWidthAndHeight + " standby='Please wait while the object is loaded...'>"; himaSagarObject = himaSagarObject + "<param name='url' value='" + sagarURL + "' />"; himaSagarObject = himaSagarObject + "<param name='src' value='" + sagarURL + "' />"; himaSagarObject = himaSagarObject + "<param name='AutoStart' value='true' />"; himaSagarObject = himaSagarObject + "<param name='Balance' value='0' />"; //-100 is fully left, 100 is fully right. himaSagarObject = himaSagarObject + "<param name='CurrentPosition' value='0' />"; //Position in seconds when starting. himaSagarObject = himaSagarObject + "<param name='showcontrols' value='true' />"; //Show play/stop/pause controls. himaSagarObject = himaSagarObject + "<param name='enablecontextmenu' value='true' />"; //Allow right-click. himaSagarObject = himaSagarObject + "<param name='fullscreen' value='" + isFullSize.ToString() + "' />"; //Start in full screen or not. himaSagarObject = himaSagarObject + "<param name='mute' value='false' />"; himaSagarObject = himaSagarObject + "<param name='PlayCount' value='1' />"; //Number of times the content will play. himaSagarObject = himaSagarObject + "<param name='rate' value='1.0' />"; //0.5=Slow, 1.0=Normal, 2.0=Fast himaSagarObject = himaSagarObject + "<param name='uimode' value='full' />"; // full, mini, custom, none, invisible himaSagarObject = himaSagarObject + "<param name='showdisplay' value='true' />"; //Show or hide the name of the file. himaSagarObject = himaSagarObject + "<param name='volume' value='50' />"; // 0=lowest, 100=highest himaSagarObject = himaSagarObject + "</object>"; return himaSagarObject; }**

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  • add an image in listview

    - by danish
    Hi I would like to add more images in my list view as this code below only displays image 1 and 2 continuously in each row. What I want to do is display a different image for each different row. Here is mycode below; Thanks for any help. I am not good at java please change the code where necessary and I can then refer to it. public class starters extends ListActivity { private static class EfficientAdapter extends BaseAdapter { private LayoutInflater mInflater; private Bitmap mIcon1; private Bitmap mIcon2; private Bitmap mIcon3; private Bitmap mIcon4; private Bitmap mIcon5; private Bitmap mIcon6; private Bitmap mIcon7; private Bitmap mIcon8; private Bitmap mIcon9; private Bitmap mIcon10; public EfficientAdapter(Context context) { // Cache the LayoutInflate to avoid asking for a new one each time. mInflater = LayoutInflater.from(context); // Icons bound to the rows. mIcon1 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters1); mIcon2 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters2); mIcon3 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters3); mIcon4 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters4); mIcon5 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters5); mIcon6 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters6); mIcon7 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters7); mIcon8 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters8); mIcon9 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters9); mIcon10 = BitmapFactory.decodeResource(context.getResources(), R.drawable.starters10); } public int getCount() { return DATA.length; } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { // A ViewHolder keeps references to children views to avoid unneccessary calls // to findViewById() on each row. ViewHolder holder; // When convertView is not null, we can reuse it directly, there is no need // to reinflate it. We only inflate a new View when the convertView supplied // by ListView is null. if (convertView == null) { convertView = mInflater.inflate(R.layout.starters, null); // Creates a ViewHolder and store references to the two children views // we want to bind data to. holder = new ViewHolder(); holder.text = (TextView) convertView.findViewById(R.id.text01); holder.text = (TextView) convertView.findViewById(R.id.secondLine); holder.icon = (ImageView) convertView.findViewById(R.id.icon01); convertView.setTag(holder); } else { // Get the ViewHolder back to get fast access to the TextView // and the ImageView. holder = (ViewHolder) convertView.getTag(); } // Bind the data efficiently with the holder. holder.text.setText(DATA[position]); holder.icon.setImageBitmap((position & 1) ==1 ? mIcon1 : mIcon2); return convertView; } static class ViewHolder { TextView text; ImageView icon; } } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setListAdapter(new EfficientAdapter(this)); } private static final String[] DATA = { "Original nachos", "Toasted chicken and cheese quesadillas", "Chicken, lime and coriander nachos", "Spicy bean and cheese quesadillas", "Tuna and corn quesadillas", "Cheesy bean and sweetcorn nachos", "Crispy chicken, avocado and lime salad", "Beef and baby corn tostada", "Spicy mexican rice with chicken and prawns", "Chilli potato boats"}; }

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  • Why is my mdadm raid-1 recovery so slow?

    - by dimmer
    On a system I'm running Ubuntu 10.04. My raid-1 restore started out fast but quickly became ridiculously slow (at this rate the restore will take 150 days!): dimmer@paimon:~$ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid1 sdc1[2] sdb1[1] 1953513408 blocks [2/1] [_U] [====>................] recovery = 24.4% (477497344/1953513408) finish=217368.0min speed=113K/sec unused devices: <none> Eventhough I have set the kernel variables to reasonably quick values: dimmer@paimon:~$ cat /proc/sys/dev/raid/speed_limit_min 1000000 dimmer@paimon:~$ cat /proc/sys/dev/raid/speed_limit_max 100000000 I am using 2 2.0TB Western Digital Hard Disks, WDC WD20EARS-00M and WDC WD20EARS-00J. I believe they have been partitioned such that their sectors are aligned. dimmer@paimon:/sys$ sudo parted /dev/sdb GNU Parted 2.2 Using /dev/sdb Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) p Model: ATA WDC WD20EARS-00M (scsi) Disk /dev/sdb: 2000GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 2000GB 2000GB ext4 (parted) unit s (parted) p Number Start End Size File system Name Flags 1 2048s 3907028991s 3907026944s ext4 (parted) q dimmer@paimon:/sys$ sudo parted /dev/sdc GNU Parted 2.2 Using /dev/sdc Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) p Model: ATA WDC WD20EARS-00J (scsi) Disk /dev/sdc: 2000GB Sector size (logical/physical): 512B/4096B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 2000GB 2000GB ext4 I am beginning to think that I have a hardware problem, otherwise I can't imagine why the mdadm restore should be so slow. I have done a benchmark on /dev/sdc using Ubuntu's disk utility GUI app, and the results looked normal so I know that sdc has the capability to write faster than this. I also had the same problem on a similar WD drive that I RMAd because of bad sectors. I suppose it's possible they sent me a replacement with bad sectors too, although there are no SMART values showing them yet. Any ideas? Thanks. As requested, output of top sorted by cpu usage (notice there is ~0 cpu usage). iowait is also zero which seems strange: top - 11:35:13 up 2 days, 9:40, 3 users, load average: 2.87, 2.58, 2.30 Tasks: 142 total, 1 running, 141 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0%us, 0.2%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 3096304k total, 1482164k used, 1614140k free, 617672k buffers Swap: 1526132k total, 0k used, 1526132k free, 535416k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 45 root 20 0 0 0 0 S 0 0.0 2:17.02 scsi_eh_0 1 root 20 0 2808 1752 1204 S 0 0.1 0:00.46 init 2 root 20 0 0 0 0 S 0 0.0 0:00.00 kthreadd 3 root RT 0 0 0 0 S 0 0.0 0:00.02 migration/0 4 root 20 0 0 0 0 S 0 0.0 0:00.17 ksoftirqd/0 5 root RT 0 0 0 0 S 0 0.0 0:00.00 watchdog/0 6 root RT 0 0 0 0 S 0 0.0 0:00.02 migration/1 ... dmesg errors, definitely looking like hardware: [202884.000157] ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [202884.007015] ata5.00: failed command: FLUSH CACHE EXT [202884.013728] ata5.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 [202884.013730] res 40/00:00:ff:59:2e/00:00:35:00:00/e0 Emask 0x4 (timeout) [202884.033667] ata5.00: status: { DRDY } [202884.040329] ata5: hard resetting link [202889.400050] ata5: link is slow to respond, please be patient (ready=0) [202894.048087] ata5: COMRESET failed (errno=-16) [202894.054663] ata5: hard resetting link [202899.412049] ata5: link is slow to respond, please be patient (ready=0) [202904.060107] ata5: COMRESET failed (errno=-16) [202904.066646] ata5: hard resetting link [202905.840056] ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [202905.849178] ata5.00: configured for UDMA/133 [202905.849188] ata5: EH complete [203899.000292] ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [203899.007096] ata5.00: failed command: IDENTIFY DEVICE [203899.013841] ata5.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 in [203899.013843] res 40/00:00:ff:f9:f6/00:00:38:00:00/e0 Emask 0x4 (timeout) [203899.041232] ata5.00: status: { DRDY } [203899.048133] ata5: hard resetting link [203899.816134] ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [203899.826062] ata5.00: configured for UDMA/133 [203899.826079] ata5: EH complete [204375.000200] ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [204375.007421] ata5.00: failed command: IDENTIFY DEVICE [204375.014799] ata5.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 in [204375.014800] res 40/00:00:ff:0c:0f/00:00:39:00:00/e0 Emask 0x4 (timeout) [204375.044374] ata5.00: status: { DRDY } [204375.051842] ata5: hard resetting link [204380.408049] ata5: link is slow to respond, please be patient (ready=0) [204384.440076] ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [204384.449938] ata5.00: configured for UDMA/133 [204384.449955] ata5: EH complete [204395.988135] ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [204395.988140] ata5.00: failed command: IDENTIFY DEVICE [204395.988147] ata5.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 in [204395.988149] res 40/00:00:ff:0c:0f/00:00:39:00:00/e0 Emask 0x4 (timeout) [204395.988151] ata5.00: status: { DRDY } [204395.988156] ata5: hard resetting link [204399.320075] ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [204399.330487] ata5.00: configured for UDMA/133 [204399.330503] ata5: EH complete

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  • My D-Link's Ethernet bridge downlink just got 10-30x slower?

    - by Jay Levitt
    TL;DR: I unplugged my network to move my desk, and now downloading via my DIR-655's Ethernet LAN bridge is 10-30x slower than the Ethernet switch it's plugged into. Background My network is SMC cable modem <-> Cisco firewall <-> Netgear switch <-> D-Link WiFi† | | | | SMC8014 ASA-5505 GS608v2 gigE DIR-655 rev A3 gigE †The DIR-655 is used as an access point, not a router (although what D-Link calls an access point, I'd call a bridge). The "WAN" port is unused; the Netgear connects to the built-in 4-port Ethernet LAN switch, inside the built- in router/firewall. Endpoints: MacBook Pro 17" mid-2010 iPhone 4S Fedora 12 Linux server running reasonably fast dual-Athlon X2, VelociRaptors, etc. All cables are <10 feet, mostly CAT-5e, some CAT-6, all premade. All WiFi endpoints are within three feet of the D-Link. Yesterday I unplugged and rearranged stuff, and now connecting via the D-Link - even through the wired switch, right next to the incoming network cable - is 30x slower than connecting directly to the Netgear switch, on both my MacBook and iPhone. How I'm measuring "slower" I'm mostly using http://speedtest.net, which of course only really measures broadband speeds. I've also installed http://www.speedtest.net/mini.php on my local server, but can't test the iPhone with that. Results Speedtest.net, closest server over Comcast business-class: CONFIG | PING (ms) | DOWN (Mbps) | UP (Mbps) Mac <-> Ethernet <-> Netgear | 9 | 31.6 | 6.8 Mac <-> Ethernet <-> D-Link | 8 | 4.1 | 6.0 Mac <-> WiFi <-> D-Link | 9 | 1.4 | 2.9 iPhone <-> WiFi <-> D-Link | 67 | 0.4 | 1.6 Speedtest Mini on Linux PC: CONFIG | DOWN (Mbps) | UP (Mbps) Mac <-> Ethernet <-> NetGear | 97.2 | 76.9 Mac <-> Ethernet <-> D-Link | 8.2 | 24.2 Mac <-> WiFi <-> D-Link | 1.0 | 8.6 Slow typing in SSH: Mac <-> Ethernet <-> Netgear <-> Linux PC: smooth Mac <-> Ethernet <-> D-Link <-> Linux PC: choppy Note that D-Link upload speeds are normal on broadband, slower locally (but I'd believe that's a D-Link limitation), and always faster than the downloads! Since ssh is choppy just with slow typing, I don't believe it's a throttling-type problem either; that's not a lot of bandwidth. What I've tried Swapping all "good" and "bad" cables Re-plugging "bad" cable from D-Link to Netgear and watching it be the "good" cable pulling cables away from power lines Verify that the Mac auto-detects the D-Link as gigE Try to verify the link speed of the D-Link <- Netgear connection, but the firmware doesn't report that Verify that the D-Link sees no TX/RX errors or collisions Use different Ethernet ports on both Netgear and D-Link Reset the D-Link to factory settings Upgrade the D-Link firmware from 1.21 to 1.35NA, 2010/11/12, the latest Reboot everything at least once On the Mac, disable Wi-Fi during the Ethernet tests, and unplug Ethernet during the Wi-Fi tests Using iStumbler, verify that the D-Link isn't picking overloaded Wi-Fi channels (usually just 1-5 neighbors on my and adjacent channels, average for my apt building) Verify that the only client connected to the Wi-Fi was the iPhone Verify that nothing was being chatty on my network according to the WISH log Enable and disable all sorts of D-Link settings, including forcing WAN auto-detect to gigE So. I don't mind buying a new access point—I wouldn't mind having a dual-link network—but as a guy who's been networking since gated v4 was a drastic rewrite, and who often used physical sniffers in the days before Wireshark, I'm baffled. I hate being baffled. What could I possibly have changed that would result in this? How can I measure it? All I can think of is a static zap—thick carpet, socks, HVAC—but I didn't feel one, and does that really happen anymore? Can I test if it's Ethernet vs. TCP layer slowness? I'm not familiar with modern network utilities; it's hard to Google without hitting "Q: Why is my network slow? A: Is your microwave on?" If I don't get an answer here, will someone big and powerful help me migrate it to serverfault without getting screamed back here? In the words of Inigo Montoya, "I must know." Don't get all Dread Pirate Roberts on me.

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  • Why can't my program display this dialog box, while another program can?

    - by nonoitall
    I'm trying to write a wrapper for Winamp input plugins and have hit a bit of a snag. I'd like my wrapper to be able to display a plugin's configuration dialog, which is (or should be) achieved by calling the plugin's Config(HWND hwndParent) function. For most plugins, this works fine and my program is able to display the plugin's configuration dialog. However, 64th Note (a plugin for playing USF files) is giving me problems. Winamp can display its configuration dialog just fine, but whenever I try to display it from my wrapper, the dialog gets destroyed before it ever shows itself. Thankfully, 64th Note is open source, so I took a look at its innards to try and get an idea of what's going wrong. I've trimmed off the irrelevant bits and am left with this: Config function in the plugin (should show configuration dialog): void Config(HWND hwndParent) { DialogBox(slave, (const char *) IDD_CONFIG_WINDOW, NULL, configDlgProc); } (Slave is the plugin DLL's HINSTANCE handle.) The proc for the dialog is as follows (I have stripped out all the functionality, since it doesn't appear to have an influence on this problem): BOOL CALLBACK configDlgProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam) { return 0; } The template for IDD_CONFIG_WINDOW is as follows: IDD_CONFIG_WINDOW DIALOGEX 0, 0, 269, 149 STYLE DS_SETFONT | DS_MODALFRAME | WS_POPUP | WS_CAPTION | WS_SYSMENU CAPTION "64th Note configuration" FONT 8, "MS Sans Serif", 0, 0, 0x0 BEGIN DEFPUSHBUTTON "OK",IDOK,212,38,50,14 CONTROL "Play Forever",IDC_NOLENGTH,"Button",BS_AUTORADIOBUTTON,7,7,55,8 CONTROL "Always Use Default Length",IDC_SETLEN,"Button",BS_AUTORADIOBUTTON,7,17,101,8 CONTROL "Default Length",IDC_DEFLEN,"Button",BS_AUTORADIOBUTTON,7,29,63,8 EDITTEXT IDC_DEFLENVAL,71,28,38,12,ES_AUTOHSCROLL EDITTEXT IDC_DEFFADEVAL,71,42,38,12,ES_AUTOHSCROLL CONTROL "Detect Silence",IDC_DETSIL,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,7,56,63,8 EDITTEXT IDC_DETSILVAL,71,56,38,12,ES_AUTOHSCROLL CONTROL "Slider2",IDC_PRISLIDER,"msctls_trackbar32",TBS_AUTOTICKS | WS_TABSTOP,74,90,108,11 EDITTEXT IDC_TITLEFMT,7,127,255,15,ES_AUTOHSCROLL CONTROL "Default to file name on missing field",IDC_FNONMISSINGTAG, "Button",BS_AUTOCHECKBOX | WS_TABSTOP,50,114,124,8 CONTROL "Use Recompiler CPU",IDC_RECOMPILER,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,7,83,8 CONTROL "Round Frequency",IDC_ROUNDFREQ,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,16,73,8 CONTROL "Seek Backwards",IDC_BACKWARDS,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,26,70,8 CONTROL "Fast Seek",IDC_FASTSEEK,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,35,48,8 CONTROL "RSP Sections",IDC_SECTIONS,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,45,60,8 CONTROL "Soft Amplify",IDC_SOFTAMP,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,54,53,8 CONTROL "Audio HLE",IDC_AUDIOHLE,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,63,50,8 CONTROL "Auto Audio HLE",IDC_AUTOAUDIOHLE,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,72,64,8 CONTROL "Display Errors",IDC_DISPERROR,"Button",BS_AUTOCHECKBOX | WS_TABSTOP,145,81,58,8 EDITTEXT IDC_RELVOL,211,104,28,12,ES_AUTOHSCROLL PUSHBUTTON "Cancel",IDCANCEL,212,54,50,14 PUSHBUTTON "Help",IDHELPBUTTON,212,71,50,14 LTEXT "Title format:",IDC_STATIC,7,113,38,8 LTEXT "seconds",IDC_STATIC,112,29,28,8 LTEXT "Default Fade",IDC_STATIC,19,43,42,8 LTEXT "seconds",IDC_STATIC,112,43,28,8 LTEXT "seconds",IDC_STATIC,112,57,28,8 CTEXT "CPU Thread Priority",IDC_STATIC,7,91,63,8 CTEXT "Look ma, I'm data!",IDC_CPUPRI,75,104,108,8 LTEXT "Relative Volume",IDC_STATIC,199,94,52,8 LTEXT "Fade Type",IDC_STATIC,7,75,35,8 COMBOBOX IDC_FADETYPE,45,72,87,74,CBS_DROPDOWNLIST | WS_TABSTOP END Naturally, without any substance in the proc function, the dialog doesn't have any functionality, but it still displays in Winamp when the Config function is invoked. However, it does not appear when I invoke it from my wrapper program. When I monitored the messages sent to the dialog in its proc function, I saw that WM_DESTROY and WM_NCDESTROY were sent within the first few messages, though I have no clue as to why. If I change the Config function so that it displays the plugin's About dialog instead of its configuration dialog, both Winamp and my wrapper will display the About dialog, which suggests that there is something unique to the configuration dialog template that's causing the problem. The modified Config function reads like so: void Config(HWND hwndParent) { DialogBox(slave, (const char *) IDD_ABOUTBOX, NULL, configDlgProc); } The template for the About dialog is as follows: IDD_ABOUTBOX DIALOGEX 0, 0, 152, 151 STYLE DS_SETFONT | DS_MODALFRAME | WS_POPUP | WS_CAPTION | WS_SYSMENU CAPTION "About 64th Note" FONT 8, "MS Sans Serif", 0, 0, 0x1 BEGIN LTEXT "64th Note v1.2 beta 3\nBased on Project 64 1.6 by Zilmar and Jabo\nAudio HLE by Azimer\nPSF concept and tagging by Neill Corlett\nPlayer by hcs, Josh W, dr0\nhttp://hcs64.com/usf",IDC_STATIC,7,94,138,50 CONTROL 110,IDC_STATIC,"Static",SS_BITMAP,26,7,95,86,WS_EX_DLGMODALFRAME END Like I said, my wrapper displays the About dialog just fine, as does Winamp. Why can Winamp display the Config dialog, while my wrapper cannot?

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  • C# - Parse HTML source as XML

    - by fonix232
    I would like to read in a dynamic URL what contains a HTML file, and read it like an XML file, based on nodes (HTML tags). Is this somehow possible? I mean, there is this HTML code: <table class="bidders" cellpadding="0" cellspacing="0"> <tr class="bidRow4"> <td>kucik (automata)</td> <td class="right">9 374 Ft</td> <td class="bidders_date">2010-06-10 18:19:52</td> </tr> <tr class="bidRow4"> <td>macszaf (automata)</td> <td class="right">9 373 Ft</td> <td class="bidders_date">2010-06-10 18:19:52</td> </tr> <tr class="bidRow2"> <td>kucik (automata)</td> <td class="right">9 372 Ft</td> <td class="bidders_date">2010-06-10 18:19:42</td> </tr> <tr class="bidRow2"> <td>macszaf (automata)</td> <td class="right">9 371 Ft</td> <td class="bidders_date">2010-06-10 18:19:42</td> </tr> <tr class="bidRow0"> <td>kucik (automata)</td> <td class="right">9 370 Ft</td> <td class="bidders_date">2010-06-10 18:19:32</td> </tr> <tr class="bidRow0"> <td>macszaf (automata)</td> <td class="right">9 369 Ft</td> <td class="bidders_date">2010-06-10 18:19:32</td> </tr> <tr class="bidRow8"> <td>kucik (automata)</td> <td class="right">9 368 Ft</td> <td class="bidders_date">2010-06-10 18:19:22</td> </tr> <tr class="bidRow8"> <td>macszaf (automata)</td> <td class="right">9 367 Ft</td> <td class="bidders_date">2010-06-10 18:19:22</td> </tr> <tr class="bidRow6"> <td>kucik (automata)</td> <td class="right">9 366 Ft</td> <td class="bidders_date">2010-06-10 18:19:12</td> </tr> <tr class="bidRow6"> <td>macszaf (automata)</td> <td class="right">9 365 Ft</td> <td class="bidders_date">2010-06-10 18:19:12</td> </tr> </table> I want to parse this into a ListView (or a Grid) to create rows with the data contained. All tr are different row, and all td in a given td is a column in the given row. And also I want it to be as fast as possible, as it would update itself in 5 seconds. Is there any library for this?

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  • Languages and VMs: Features that are hard to optimize and why

    - by mrjoltcola
    I'm doing a survey of features in preparation for a research project. Name a mainstream language or language feature that is hard to optimize, and why the feature is or isn't worth the price paid, or instead, just debunk my theories below with anecdotal evidence. Before anyone flags this as subjective, I am asking for specific examples of languages or features, and ideas for optimization of these features, or important features that I haven't considered. Also, any references to implementations that prove my theories right or wrong. Top on my list of hard to optimize features and my theories (some of my theories are untested and are based on thought experiments): 1) Runtime method overloading (aka multi-method dispatch or signature based dispatch). Is it hard to optimize when combined with features that allow runtime recompilation or method addition. Or is it just hard, anyway? Call site caching is a common optimization for many runtime systems, but multi-methods add additional complexity as well as making it less practical to inline methods. 2) Type morphing / variants (aka value based typing as opposed to variable based) Traditional optimizations simply cannot be applied when you don't know if the type of someting can change in a basic block. Combined with multi-methods, inlining must be done carefully if at all, and probably only for a given threshold of size of the callee. ie. it is easy to consider inlining simple property fetches (getters / setters) but inlining complex methods may result in code bloat. The other issue is I cannot just assign a variant to a register and JIT it to the native instructions because I have to carry around the type info, or every variable needs 2 registers instead of 1. On IA-32 this is inconvenient, even if improved with x64's extra registers. This is probably my favorite feature of dynamic languages, as it simplifies so many things from the programmer's perspective. 3) First class continuations - There are multiple ways to implement them, and I have done so in both of the most common approaches, one being stack copying and the other as implementing the runtime to use continuation passing style, cactus stacks, copy-on-write stack frames, and garbage collection. First class continuations have resource management issues, ie. we must save everything, in case the continuation is resumed, and I'm not aware if any languages support leaving a continuation with "intent" (ie. "I am not coming back here, so you may discard this copy of the world"). Having programmed in the threading model and the contination model, I know both can accomplish the same thing, but continuations' elegance imposes considerable complexity on the runtime and also may affect cache efficienty (locality of stack changes more with use of continuations and co-routines). The other issue is they just don't map to hardware. Optimizing continuations is optimizing for the less-common case, and as we know, the common case should be fast, and the less-common cases should be correct. 4) Pointer arithmetic and ability to mask pointers (storing in integers, etc.) Had to throw this in, but I could actually live without this quite easily. My feelings are that many of the high-level features, particularly in dynamic languages just don't map to hardware. Microprocessor implementations have billions of dollars of research behind the optimizations on the chip, yet the choice of language feature(s) may marginalize many of these features (features like caching, aliasing top of stack to register, instruction parallelism, return address buffers, loop buffers and branch prediction). Macro-applications of micro-features don't necessarily pan out like some developers like to think, and implementing many languages in a VM ends up mapping native ops into function calls (ie. the more dynamic a language is the more we must lookup/cache at runtime, nothing can be assumed, so our instruction mix is made up of a higher percentage of non-local branching than traditional, statically compiled code) and the only thing we can really JIT well is expression evaluation of non-dynamic types and operations on constant or immediate types. It is my gut feeling that bytecode virtual machines and JIT cores are perhaps not always justified for certain languages because of this. I welcome your answers.

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  • Modern alternatives to Java

    - by Ralph
    I have been a Java developer for 14 years and have written an enterprise-level (~500 kloc) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. Are there other JVM-based languages that can be used for enterprise level development?

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  • Choosing a type for search results in C#

    - by Chris M
    I have a result set that will never exceed 500; the results that come back from the web-service are assigned to a search results object. The data from the webservice is about 2mb; the bit I want to use is about a third of each record, so this allows me to cache and quickly manipulate it. I want to be able to sort and filter the results with the least amount of overhead and as fast as possible so I used the VCSKICKS timing class to measure their performance Average Total (10,000) Type Create Sort Create Sort HashSet 0.1579 0.0003 1579 3 IList 0.0633 0.0002 633 2 IQueryable 0.0072 0.0432 72 432 Measured in Seconds using http://www.vcskicks.com/algorithm-performance.php I created the hashset through a for loop over the web-service response (adding to the hashset). The List & IQueryable were created using LINQ. Question I can understand why HashSet takes longer to create (the foreach loop vs linq); but why would IQueryable take longer to sort than the other two; and finally is there a better way to assign the HashSet. Thanks Actual Program public class Program { private static AuthenticationHeader _authHeader; private static OPSoapClient _opSession; private static AccommodationSearchResponse _searchResults; private static HashSet<SearchResults> _myHash; private static IList<SearchResults> _myList; private static IQueryable<SearchResults> _myIQuery; static void Main(string[] args) { #region Setup WebService _authHeader = new AuthenticationHeader { UserName = "xx", Password = "xx" }; _opSession = new OPSoapClient(); #region Setup Search Results _searchResults = _opgSession.SearchCR(_authHeader, "ENG", "GBP", "GBR"); #endregion Setup Search Results #endregion Setup WebService // HASHSET SpeedTester hashTest = new SpeedTester(TestHashSet); hashTest.RunTest(); Console.WriteLine("- Hash Test \nAverage Running Time: {0}; Total Time: {1}", hashTest.AverageRunningTime, hashTest.TotalRunningTime); SpeedTester hashSortTest = new SpeedTester(TestSortingHashSet); hashSortTest.RunTest(); Console.WriteLine("- Hash Sort Test \nAverage Running Time: {0}; Total Time: {1}", hashSortTest.AverageRunningTime, hashSortTest.TotalRunningTime); // ILIST SpeedTester listTest = new SpeedTester(TestList); listTest.RunTest(); Console.WriteLine("- List Test \nAverage Running Time: {0}; Total Time: {1}", listTest.AverageRunningTime, listTest.TotalRunningTime); SpeedTester listSortTest = new SpeedTester(TestSortingList); listSortTest.RunTest(); Console.WriteLine("- List Sort Test \nAverage Running Time: {0}; Total Time: {1}", listSortTest.AverageRunningTime, listSortTest.TotalRunningTime); // IQUERIABLE SpeedTester iqueryTest = new SpeedTester(TestIQueriable); iqueryTest.RunTest(); Console.WriteLine("- iquery Test \nAverage Running Time: {0}; Total Time: {1}", iqueryTest.AverageRunningTime, iqueryTest.TotalRunningTime); SpeedTester iquerySortTest = new SpeedTester(TestSortableIQueriable); iquerySortTest.RunTest(); Console.WriteLine("- iquery Sort Test \nAverage Running Time: {0}; Total Time: {1}", iquerySortTest.AverageRunningTime, iquerySortTest.TotalRunningTime); } static void TestHashSet() { var test = _searchResults.Items; _myHash = new HashSet<SearchResults>(); foreach(var x in test) { _myHash.Add(new SearchResults { Ref = x.Ref, Price = x.StandardPrice }); } } static void TestSortingHashSet() { var sorted = _myHash.OrderBy(s => s.Price); } static void TestList() { var test = _searchResults.Items; _myList = (from x in test select new SearchResults { Ref = x.Ref, Price = x.StandardPrice }).ToList(); } static void TestSortingList() { var sorted = _myList.OrderBy(s => s.Price); } static void TestIQueriable() { var test = _searchResults.Items; _myIQuery = (from x in test select new SearchResults { Ref = x.Ref, Price = x.StandardPrice }).AsQueryable(); } static void TestSortableIQueriable() { var sorted = _myIQuery.OrderBy(s => s.Price); } }

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  • Why does this Quicksort work?

    - by IVlad
    I find this Quicksort partitioning approach confusing and wrong, yet it seems to work. I am referring to this pseudocode. Note: they also have a C implementation at the end of the article, but it's very different from their pseudocode, so I don't care about that. I have also written it in C like this, trying to stay true to the pseudocode as much as possible, even if that means doing some weird C stuff: #include <stdio.h> int partition(int a[], int p, int r) { int x = a[p]; int i = p - 1; int j = r + 1; while (1) { do j = j - 1; while (!(a[j] <= x)); do i = i + 1; while (!(a[i] >= x)); if (i < j) { int t = a[i]; a[i] = a[j]; a[j] = t; } else { for (i = 1; i <= a[0]; ++i) printf("%d ", a[i]); printf("- %d\n", j); return j; } } } int main() { int a[100] = //{8, 6,10,13,15,8,3,2,12}; {7, 7, 6, 2, 3, 8, 4, 1}; partition(a, 1, a[0]); return 0; } If you run this, you'll get the following output: 1 6 2 3 4 8 7 - 5 However, this is wrong, isn't it? Clearly a[5] does not have all the values before it lower than it, since a[2] = 6 > a[5] = 4. Not to mention that 7 is supposed to be the pivot (the initial a[p]) and yet its position is both incorrect and lost. The following partition algorithm is taken from wikipedia: int partition2(int a[], int p, int r) { int x = a[r]; int store = p; for (int i = p; i < r; ++i) { if (a[i] <= x) { int t = a[i]; a[i] = a[store]; a[store] = t; ++store; } } int t = a[r]; a[r] = a[store]; a[store] = t; for (int i = 1; i <= a[0]; ++i) printf("%d ", a[i]); printf("- %d\n", store); return store; } And produces this output: 1 6 2 3 8 4 7 - 1 Which is a correct result in my opinion: the pivot (a[r] = a[7]) has reached its final position. However, if I use the initial partitioning function in the following algorithm: void Quicksort(int a[], int p, int r) { if (p < r) { int q = partition(a, p, r); // initial partitioning function Quicksort(a, p, q); Quicksort(a, q + 1, r); // I'm pretty sure q + r was a typo, it doesn't work with q + r. } } ... it seems to be a correct sorting algorithm. I tested it out on a lot of random inputs, including all 0-1 arrays of length 20. I have also tried using this partition function for a selection algorithm, in which it failed to produce correct results. It seems to work and it's even very fast as part of the quicksort algorithm however. So my questions are: Can anyone post an example on which the algorithm DOESN'T work? If not, why does it work, since the partitioning part seems to be wrong? Is this another partitioning approach that I don't know about?

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  • Neo4j increasing latency as SKIP increases on Cypher query + REST API

    - by voldomazta
    My setup: Java(TM) SE Runtime Environment (build 1.7.0_45-b18) Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode) Neo4j 2.0.0-M06 Enterprise First I made sure I warmed up the cache by executing the following: START n=node(*) RETURN COUNT(n); START r=relationship(*) RETURN count(r); The size of the table is 63,677 nodes and 7,169,995 relationships Now I have the following query: START u1=node:node_auto_index('uid:39') MATCH (u1:user)-[w:WANTS]->(c:card)<-[h:HAS]-(u2:user) WHERE u2.uid <> 39 WITH u2.uid AS uid, (CASE WHEN w.qty < h.qty THEN w.qty ELSE h.qty END) AS have RETURN uid, SUM(have) AS total ORDER BY total DESC SKIP 0 LIMIT 25 This UID has about 40k+ results that I want to be able to put a pagination to. The initial skip was around 773ms. I tried page 2 (skip 25) and the latency was around the same even up to page 500 it only rose up to 900ms so I didn't really bother. Now I tried some fast forward paging and jumped by thousands so I did 1000, then 2000, then 3000. I was hoping the ORDER BY arrangement will already have been cached by Neo4j and using SKIP will just move to that index in the result and wont have to iterate through each one again. But for each thousand skip I made the latency increased by alot. It's not just cache warming because for one I already warmed up the cache and two, I tried the same skip a couple of times for each skip and it yielded the same results: SKIP 0: 773ms SKIP 1000: 1369ms SKIP 2000: 2491ms SKIP 3000: 3899ms SKIP 4000: 5686ms SKIP 5000: 7424ms Now who the hell would want to view 5000 pages of results? 40k even?! :) Good point! I will probably put a cap on the maximum results a user can view but I was just curious about this phenomenon. Will somebody please explain why Neo4j seems to be re-iterating through stuff which appears to be already known to it? Here is my profiling for the 0 skip: ==> ColumnFilter(symKeys=["uid", " INTERNAL_AGGREGATE65c4d6a2-1930-4f32-8fd9-5e4399ce6f14"], returnItemNames=["uid", "total"], _rows=25, _db_hits=0) ==> Slice(skip="Literal(0)", _rows=25, _db_hits=0) ==> Top(orderBy=["SortItem(Cached( INTERNAL_AGGREGATE65c4d6a2-1930-4f32-8fd9-5e4399ce6f14 of type Any),false)"], limit="Add(Literal(0),Literal(25))", _rows=25, _db_hits=0) ==> EagerAggregation(keys=["uid"], aggregates=["( INTERNAL_AGGREGATE65c4d6a2-1930-4f32-8fd9-5e4399ce6f14,Sum(have))"], _rows=41659, _db_hits=0) ==> ColumnFilter(symKeys=["have", "u1", "uid", "c", "h", "w", "u2"], returnItemNames=["uid", "have"], _rows=146826, _db_hits=0) ==> Extract(symKeys=["u1", "c", "h", "w", "u2"], exprKeys=["uid", "have"], _rows=146826, _db_hits=587304) ==> Filter(pred="((NOT(Product(u2,uid(0),true) == Literal(39)) AND hasLabel(u1:user(0))) AND hasLabel(u2:user(0)))", _rows=146826, _db_hits=146826) ==> TraversalMatcher(trail="(u1)-[w:WANTS WHERE (hasLabel(NodeIdentifier():card(1)) AND hasLabel(NodeIdentifier():card(1))) AND true]->(c)<-[h:HAS WHERE (NOT(Product(NodeIdentifier(),uid(0),true) == Literal(39)) AND hasLabel(NodeIdentifier():user(0))) AND true]-(u2)", _rows=146826, _db_hits=293696) And for the 5000 skip: ==> ColumnFilter(symKeys=["uid", " INTERNAL_AGGREGATE99329ea5-03cd-4d53-a6bc-3ad554b47872"], returnItemNames=["uid", "total"], _rows=25, _db_hits=0) ==> Slice(skip="Literal(5000)", _rows=25, _db_hits=0) ==> Top(orderBy=["SortItem(Cached( INTERNAL_AGGREGATE99329ea5-03cd-4d53-a6bc-3ad554b47872 of type Any),false)"], limit="Add(Literal(5000),Literal(25))", _rows=5025, _db_hits=0) ==> EagerAggregation(keys=["uid"], aggregates=["( INTERNAL_AGGREGATE99329ea5-03cd-4d53-a6bc-3ad554b47872,Sum(have))"], _rows=41659, _db_hits=0) ==> ColumnFilter(symKeys=["have", "u1", "uid", "c", "h", "w", "u2"], returnItemNames=["uid", "have"], _rows=146826, _db_hits=0) ==> Extract(symKeys=["u1", "c", "h", "w", "u2"], exprKeys=["uid", "have"], _rows=146826, _db_hits=587304) ==> Filter(pred="((NOT(Product(u2,uid(0),true) == Literal(39)) AND hasLabel(u1:user(0))) AND hasLabel(u2:user(0)))", _rows=146826, _db_hits=146826) ==> TraversalMatcher(trail="(u1)-[w:WANTS WHERE (hasLabel(NodeIdentifier():card(1)) AND hasLabel(NodeIdentifier():card(1))) AND true]->(c)<-[h:HAS WHERE (NOT(Product(NodeIdentifier(),uid(0),true) == Literal(39)) AND hasLabel(NodeIdentifier():user(0))) AND true]-(u2)", _rows=146826, _db_hits=293696) The only difference is the LIMIT clause on the Top function. I hope we can make this work as intended, I really don't want to delve into doing an embedded Neo4j + my own Jetty REST API for the web app.

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  • What is the fastest way to Initialize a multi-dimensional array to non-default values in .NET?

    - by AMissico
    How do I initialize a multi-dimensional array of a primitive type as fast as possible? I am stuck with using multi-dimensional arrays. My problem is performance. The following routine initializes a 100x100 array in approx. 500 ticks. Removing the int.MaxValue initialization results in approx. 180 ticks just for the looping. Approximately 100 ticks to create the array without looping and without initializing to int.MaxValue. Routines similiar to this are called a few hundred-thousand to several million times during a "run". The array size will not change during a run and arrays are created one-at-a-time, used, then discarded, and a new array created. A "run" which may last from one minute (using 10x10 arrays) to forty-five minutes (100x100). The application creates arrays of int, bool, and struct. There can be multiple "runs" executing at same time, but are not because performance degrades terribly. I am using 100x100 as a base-line. I am open to suggestions on how to optimize this non-default initialization of an array. One idea I had is to use a smaller primitive type when available. For instance, using byte instead of int, saves 100 ticks. I would be happy with this, but I am hoping that I don't have to change the primitive data type. public int[,] CreateArray(Size size) { int[,] array = new int[size.Width, size.Height]; for (int x = 0; x < size.Width; x++) { for (int y = 0; y < size.Height; y++) { array[x, y] = int.MaxValue; } } return array; } Down to 450 ticks with the following: public int[,] CreateArray1(Size size) { int iX = size.Width; int iY = size.Height; int[,] array = new int[iX, iY]; for (int x = 0; x < iX; x++) { for (int y = 0; y < iY; y++) { array[x, y] = int.MaxValue; } } return array; } Down to approximately 165 ticks after a one-time initialization of 2800 ticks. (See my answer below.) If I can get stackalloc to work with multi-dimensional arrays, I should be able to get the same performance without having to intialize the private static array. private static bool _arrayInitialized5; private static int[,] _array5; public static int[,] CreateArray5(Size size) { if (!_arrayInitialized5) { int iX = size.Width; int iY = size.Height; _array5 = new int[iX, iY]; for (int x = 0; x < iX; x++) { for (int y = 0; y < iY; y++) { _array5[x, y] = int.MaxValue; } } _arrayInitialized5 = true; } return (int[,])_array5.Clone(); } Down to approximately 165 ticks without using the "clone technique" above. (See my answer below.) I am sure I can get the ticks lower, if I can just figure out the return of CreateArray9. public unsafe static int[,] CreateArray8(Size size) { int iX = size.Width; int iY = size.Height; int[,] array = new int[iX, iY]; fixed (int* pfixed = array) { int count = array.Length; for (int* p = pfixed; count-- > 0; p++) *p = int.MaxValue; } return array; }

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  • jQuery hold form submit until "continue" button pressed

    - by Seán McCabe
    I am trying to submit a form, which I have had working, but have now modified it to include a modal jQuery UI box, so that it won't submit until the user presses "continue". I've had various problems with this, including getting the form to hold until that button is pressed, but I think I have found a solution to that, but implementing it, I am getting a SyntaxError which I can't find the source of. With the help of kevin B managed to find the answer was the form was submitting, but the returned JSON response wasn't quite formatted right. The response was that the form wasn't being submitted, so that problem is still occurring. So updated the code with the provided feedback, now need to find out why the form isnt submitting. I know its something to do with the 2nd function isnt recognising the submit button has been pressed, so need to know how to submit that form data without the form needing to be submitted again. Below is the new code: function submitData() { $("#submitProvData").submit(function(event) { event.preventDefault(); var gTotal, sTotal, dfd; var dfd = new $.Deferred(); $('html,body').animate({ scrollTop: 0 }, 'fast'); $("#submitProvData input").css("border", "1px solid #aaaaaa"); $("#submitProvData input[readonly='readonly']").css("border", "none"); sTotal = $('#summaryTotal').val(); gTotal = $('#gptotal').val(); if(gTotal !== 'sTotal'){ $("#newsupinvbox").append('<div id="newsupinvdiagbox" title="Warning - Totals do not match" class="hidden"><p>Press "Continue", to submit the invoice flagged for attention.</p> <br /><p class="italic">or</p><br /> <p>Press "Correct" to correct the discrepancy.</p></div>') //CREATE DIV //SET $("#newsupinvdiagbox").dialog({ resizable: false, autoOpen:false, modal: true, draggable: false, width:380, height:240, closeOnEscape: false, position: ['center',20], buttons: { 'Continue': function() { $(this).dialog('close'); reData(); }, // end continue button 'Correct': function() { $(this).dialog('close'); return false; } //end cancel button }//end buttons });//end dialog $('#newsupinvdiagbox').dialog('open'); } return false; }); } function reData() { console.log('submitted'); $("#submitProvData").submit(function(resubmit){ console.log('form submit'); var formData; formData = new FormData($(this)[0]); $.ajax({ type: "POST", url: "functions/invoicing_upload_provider.php", data: formData, async: false, success: function(result) { $.each($.parseJSON(result), function(item, value){ if(item == 'Success'){ $('#newsupinv_window_message_success_mes').html('The provider invoice was uploaded successfully.'); $('#newsupinv_window_message_success').fadeIn(300, function (){ reset(); }).delay(2500).fadeOut(700); } else if(item == 'Error'){ $('#newsupinv_window_message_error_mes').html(value); $('#newsupinv_window_message_error').fadeIn(300).delay(3000).fadeOut(700); } else if(item == 'Warning'){ $('#newsupinv_window_message_warning_mes').html(value); $('#newsupinv_window_message_warning').fadeIn(300, function (){ reset(); }).delay(2500).fadeOut(700); } }); }, error: function() { $('#newsupinv_window_message_error_mes').html("An error occured, the form was not submitted"); $('#newsupinv_window_message_error').fadeIn(300); $('#newsupinv_window_message_error').delay(3000).fadeOut(700); }, cache: false, contentType: false, processData: false }); }); }

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  • Code runs 6 times slower with 2 threads than with 1

    - by Edward Bird
    So I have written some code to experiment with threads and do some testing. The code should create some numbers and then find the mean of those numbers. I think it is just easier to show you what I have so far. I was expecting with two threads that the code would run about 2 times as fast. Measuring it with a stopwatch I think it runs about 6 times slower! void findmean(std::vector<double>*, std::size_t, std::size_t, double*); int main(int argn, char** argv) { // Program entry point std::cout << "Generating data..." << std::endl; // Create a vector containing many variables std::vector<double> data; for(uint32_t i = 1; i <= 1024 * 1024 * 128; i ++) data.push_back(i); // Calculate mean using 1 core double mean = 0; std::cout << "Calculating mean, 1 Thread..." << std::endl; findmean(&data, 0, data.size(), &mean); mean /= (double)data.size(); // Print result std::cout << " Mean=" << mean << std::endl; // Repeat, using two threads std::vector<std::thread> thread; std::vector<double> result; result.push_back(0.0); result.push_back(0.0); std::cout << "Calculating mean, 2 Threads..." << std::endl; // Run threads uint32_t halfsize = data.size() / 2; uint32_t A = 0; uint32_t B, C, D; // Split the data into two blocks if(data.size() % 2 == 0) { B = C = D = halfsize; } else if(data.size() % 2 == 1) { B = C = halfsize; D = hsz + 1; } // Run with two threads thread.push_back(std::thread(findmean, &data, A, B, &(result[0]))); thread.push_back(std::thread(findmean, &data, C, D , &(result[1]))); // Join threads thread[0].join(); thread[1].join(); // Calculate result mean = result[0] + result[1]; mean /= (double)data.size(); // Print result std::cout << " Mean=" << mean << std::endl; // Return return EXIT_SUCCESS; } void findmean(std::vector<double>* datavec, std::size_t start, std::size_t length, double* result) { for(uint32_t i = 0; i < length; i ++) { *result += (*datavec).at(start + i); } } I don't think this code is exactly wonderful, if you could suggest ways of improving it then I would be grateful for that also.

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  • Algorithm to select groups of similar items in 2d array

    - by mafutrct
    There is a 2d array of items (in my case they are called Intersections). A certain item is given as a start. The task is to find all items directly or indirectly connected to this item that satisfy a certain function. So the basic algorithm is like this: Add the start to the result list. Repeat until no modification: Add each item in the array that satisfies the function and touches any item in the result list to the result list. My current implementation looks like this: private IList<Intersection> SelectGroup ( Intersection start, Func<Intersection, Intersection, bool> select) { List<Intersection> result = new List<Intersection> (); Queue<Intersection> source = new Queue<Intersection> (); source.Enqueue (start); while (source.Any ()) { var s = source.Dequeue (); result.Add (s); foreach (var neighbour in Neighbours (s)) { if (select (start, neighbour) && !result.Contains (neighbour) && !source.Contains (neighbour)) { source.Enqueue (neighbour); } } } Debug.Assert (result.Distinct ().Count () == result.Count ()); Debug.Assert (result.All (x => select (x, result.First ()))); return result; } private List<Intersection> Neighbours (IIntersection intersection) { int x = intersection.X; int y = intersection.Y; List<Intersection> list = new List<Intersection> (); if (x > 1) { list.Add (GetIntersection (x - 1, y)); } if (y > 1) { list.Add (GetIntersection (x, y - 1)); } if (x < Size) { list.Add (GetIntersection (x + 1, y)); } if (y < Size) { list.Add (GetIntersection (x, y + 1)); } return list; } (The select function takes a start item and returns true iff the second item satisfies.) This does its job and turned out to be reasonable fast for the usual array sizes (about 20*20). However, I'm interested in further improvements. Any ideas? Example (X satisfies in relation to other Xs, . does never satisfy): .... XX.. .XX. X... In this case, there are 2 groups: a central group of 4 items and a group of a single item in the lower left. Selecting the group (for instance by starting item [2, 2]) returns the former, while the latter can be selected using the starting item and sole return value [0, 3]. Example 2: .A.. ..BB A.AA This time there are 4 groups. The 3 A groups are not connected, so they are returned as separate groups. The bigger A and B groups are connected, but A does not related to B so they are returned as separate groups.

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  • Custom Online Backup Solution Advice

    - by Martín Marconcini
    I have to implement a way so our customers can backup their SQL 2000/5/8 databasase online. The application they use is a C#/.NET35 Winforms application that connects to a SQL Server (can be 2000/2005/2008, sometimes express editions). The SQL Server is on the same LAN. Our application has a very specific UI and we must code each form following those guidelines. There’s lots of GDI+ to give it the look and feel we want. For that reason, using a 3rd party application is not a very good idea. We need to charge the customer on a monthly/annual basis for the service. Preferably, the customer doesn’t need to care about bandwidth and storage space. It must be transparent. Given the above reqs., my first thoughts are: Solution 1: Code some sort of FTP basic functionality with behind the scenes SQL Backup mechanism, then hire a Hosting service and compress-transfer the .BAK to the Hosting. Maintain a series of Folders (for each customer). They won’t see what’s happening. They will just see a list of their files and a big “Backup now” button that will perform the SQL backup, compress it and upload it (and update the file list) ;) Pros: Not very complicated to implement, simple to use, fairly simple to configure (could have a dedicated ftp user/pass) Cons: Finding a “ftp” only hosting plan is not probably going to be easy, they usually come with a bunch of stuff. FTP is not always the best protocol. more? Solution 2: Similar to 1, but instead of FTP, find a cloud computing service like Amazon S3, Mosso or similar. Pros: Cloud Storage is fast, reliable, etc. It’s kind of easy to implement (specially if there are APIs like AWS or Mosso). Cons: I have been unable to come up with a service optimized for resellers where I can give multiple sub-accounts (one for each customer). Billing is going to be a nightmare cuz these services bill per/GB and with One account it’s impossible to differentiate each customer. Solution 3: Similar to 2, but letting the user create their own account on Amazon S3 (for example). Pros: You forget about billing and such. Cons: A mess for the customer who has to open the Amazon (or whatever) account, will be charged for that and not from you. You can’t really charge the customer (since you’re just not doing anything). Solution 4: Use one of the many backup online solutions that use the tech in cloud storage. Pros: many of these include SQL Server backup, and a lot of features that we’d have to implement. Plus web access and stuff like that will come included. Cons: Still have the billing problem described in number 2. Little of these companies (if any) offers “reseller” accounts. You have to eventually use their software (some offer certain branding). Any better approach? Summary: You have a software (.NET Winapp). You want your users to be able to backup their SQL Server databases online (and be able to retrieve the backups if needed). You ideally would like to charge the customer for this service (i.e. XX € a year).

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  • weighted RNG speed problem in C++

    - by supert
    I have a (fast) bit of C++ code that samples cards from a 52 card deck: void sample_allcards(int table[5], int holes[], int players) { int temp[5 + 2 * players]; bool try_again; int c, n, i; for (i = 0; i < 5 + 2 * players; i++) { try_again = true; while (try_again == true) { try_again = false; c = fast_rand52(); // reject collisions for (n = 0; n < i + 1; n++) { try_again = (temp[n] == c) || try_again; } temp[i] = c; } } copy_cards(table, temp, 5); copy_cards(holes, temp + 5, 2 * players); } I am implementing code to sample the hole cards according to a known distribution (stored as a 2d table). My code for this looks like: void sample_allcards_weighted(double weights[][HOLE_CARDS], int table[5], int holes[], int players) { // weights are distribution over hole cards int temp[5 + 2 * players]; int n, i; // table cards for (i = 0; i < 5; i++) { bool try_again = true; while (try_again == true) { try_again = false; int c = fast_rand52(); // reject collisions for (n = 0; n < i + 1; n++) { try_again = (temp[n] == c) || try_again; } temp[i] = c; } } for (int player = 0; player < players; player++) { // hole cards according to distribution i = 5 + 2 * player; bool try_again = true; while (try_again == true) { try_again = false; // weighted-sample c1 and c2 at once double w[1326]; memcpy(w, weights[player], sizeof(w)); // h is a number < 1325 int h = weighted_randi(w, HOLE_CARDS); // i2h uses h and sets temp[i] to the 2 cards implied by h i2h(&temp[i], h); // reject collisions for (n = 0; n < i; n++) { try_again = (temp[n] == temp[i]) || (temp[n] == temp[i+1]) || try_again; } } } copy_cards(table, temp, 5); copy_cards(holes, temp + 5, 2 * players); } My problem? The weighted sampling algorithm is a factor of 10 slower. Speed is very important for my application. Is there a way to improve the speed of my algorithm to something more reasonable? Am I doing something wrong in my implementation? Thanks.

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  • Make interchangeable class types via pointer casting only, without having to allocate any new objects?

    - by HostileFork
    UPDATE: I do appreciate "don't want that, want this instead" suggestions. They are useful, especially when provided in context of the motivating scenario. Still...regardless of goodness/badness, I've become curious to find a hard-and-fast "yes that can be done legally in C++11" vs "no it is not possible to do something like that". I want to "alias" an object pointer as another type, for the sole purpose of adding some helper methods. The alias cannot add data members to the underlying class (in fact, the more I can prevent that from happening the better!) All aliases are equally applicable to any object of this type...it's just helpful if the type system can hint which alias is likely the most appropriate. There should be no information about any specific alias that is ever encoded in the underlying object. Hence, I feel like you should be able to "cheat" the type system and just let it be an annotation...checked at compile time, but ultimately irrelevant to the runtime casting. Something along these lines: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Under the hood, the factory method is actually making a NodeBase class, and then using a similar reinterpret_cast to return it as a Node<AccessorFoo>*. The easy way to avoid this is to make these lightweight classes that wrap nodes and are passed around by value. Thus you don't need casting, just Accessor classes that take the node handle to wrap in their constructor: AccessorFoo foo (NodeBase::createViaFactory()); AccessorBar bar (foo.getNode()); But if I don't have to pay for all that, I don't want to. That would involve--for instance--making a special accessor type for each sort of wrapped pointer (AccessorFooShared, AccessorFooUnique, AccessorFooWeak, etc.) Having these typed pointers being aliased for one single pointer-based object identity is preferable, and provides a nice orthogonality. So back to that original question: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Seems like there would be some way to do this that might be ugly but not "break the rules". According to ISO14882:2011(e) 5.2.10-7: An object pointer can be explicitly converted to an object pointer of a different type.70 When a prvalue v of type "pointer to T1" is converted to the type "pointer to cv T2", the result is static_cast(static_cast(v)) if both T1 and T2 are standard-layout types (3.9) and the alignment requirements of T2 are no stricter than those of T1, or if either type is void. Converting a prvalue of type "pointer to T1" to the type "pointer to T2" (where T1 and T2 are object types and where the alignment requirements of T2 are no stricter than those of T1) and back to its original type yields the original pointer value. The result of any other such pointer conversion is unspecified. Drilling into the definition of a "standard-layout class", we find: has no non-static data members of type non-standard-layout-class (or array of such types) or reference, and has no virtual functions (10.3) and no virtual base classes (10.1), and has the same access control (clause 11) for all non-static data members, and has no non-standard-layout base classes, and either has no non-static data member in the most-derived class and at most one base class with non-static data members, or has no base classes with non-static data members, and has no base classes of the same type as the first non-static data member. Sounds like working with something like this would tie my hands a bit with no virtual methods in the accessors or the node. Yet C++11 apparently has std::is_standard_layout to keep things checked. Can this be done safely? Appears to work in gcc-4.7, but I'd like to be sure I'm not invoking undefined behavior.

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  • is Boost Library's weighted median broken?

    - by user624188
    I confess that I am no expert in C++. I am looking for a fast way to compute weighted median, which Boost seemed to have. But it seems I am not able to make it work. #include <iostream> #include <boost/accumulators/accumulators.hpp> #include <boost/accumulators/statistics/stats.hpp> #include <boost/accumulators/statistics/median.hpp> #include <boost/accumulators/statistics/weighted_median.hpp> using namespace boost::accumulators; int main() { // Define an accumulator set accumulator_set<double, stats<tag::median > > acc1; accumulator_set<double, stats<tag::median >, float> acc2; // push in some data ... acc1(0.1); acc1(0.2); acc1(0.3); acc1(0.4); acc1(0.5); acc1(0.6); acc2(0.1, weight=0.); acc2(0.2, weight=0.); acc2(0.3, weight=0.); acc2(0.4, weight=1.); acc2(0.5, weight=1.); acc2(0.6, weight=1.); // Display the results ... std::cout << " Median: " << median(acc1) << std::endl; std::cout << "Weighted Median: " << median(acc2) << std::endl; return 0; } produces the following output, which is clearly wrong. Median: 0.3 Weighted Median: 0.3 Am I doing something wrong? Any help will be greatly appreciated. * however, the weighted sum works correctly * @glowcoder: The weighted sum works perfectly fine like this. #include <iostream> #include <boost/accumulators/accumulators.hpp> #include <boost/accumulators/statistics/stats.hpp> #include <boost/accumulators/statistics/sum.hpp> #include <boost/accumulators/statistics/weighted_sum.hpp> using namespace boost::accumulators; int main() { // Define an accumulator set accumulator_set<double, stats<tag::sum > > acc1; accumulator_set<double, stats<tag::sum >, float> acc2; // accumulator_set<double, stats<tag::median >, float> acc2; // push in some data ... acc1(0.1); acc1(0.2); acc1(0.3); acc1(0.4); acc1(0.5); acc1(0.6); acc2(0.1, weight=0.); acc2(0.2, weight=0.); acc2(0.3, weight=0.); acc2(0.4, weight=1.); acc2(0.5, weight=1.); acc2(0.6, weight=1.); // Display the results ... std::cout << " Median: " << sum(acc1) << std::endl; std::cout << "Weighted Median: " << sum(acc2) << std::endl; return 0; } and the result is Sum: 2.1 Weighted Sum: 1.5

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