writing - Page 460 - Developer IT

surfaceDestroyed called out of turn

- by Avasulthiris

I'm currently developing on minimum sdk version 3 (Android 1.5 - cupcake) and I'm having a strange unexplained issue that I have not been able to solve on my own. It is now becoming a rather urgent issue as I've already missed 1 deadline... I'm writing a high-level library to make long term android development easier and quicker. The one specific module has to capture images for a application... I've gotten everything right so far over the last couple months, except this one little thing and I don't know what to do any more: When I use the Camera object and implement a SurfaceHolder.Callback, the methods surfaceCreated() and surfaceChanged() are called one after the other. Then when the activity finishes, surfaceDestroyed() is called. This is how it should be, but when I stick the exact same code in my library (plain Java library that references the Android API - not in an activity), surfaceDestroyed() is called directly after created and changed. As a result - the camera object is closed before I can use it and the application force closes. What a pain. I can't do anything! This method call is controlled by the device.. Why does the surface close for no reason? Even when I post it to run on the activity thread through my own invokeAndWait(Runnable) method, like I do for many other things. I have 5 different working examples of different ways and implementations of capturing images in android but I still get the same issue when I plug it into my library. I don't understand what the difference is. The code is pretty much the same - and I post all the related code to the UI thread so its not a thread handling issue or anything like that. I've rewritten it about 20 times in different ways - same issue every time.. The only other way to approach it that I know of is creating a new Camera and setting it to the VideoView. The android source (c++ native code) however provides no Camera constructor, only an open() method which automatically forwards the camera's state to 'prepared' but I can only set the camera to the VideoView from the 'initialized' state. Pretty silly, I know, but there is no way around it unless I modify the Android library source code haha. not an option! The API does not allow for this method - you are expected to use it like my first example. So essentially - i just need to understand exactly why surfaceDestroyed() is called out of turn and if there is anything I can do to avoid it closing? If i can just understand the exact logic behind it and how it works! The documentation isn't much help! Secondly, if someone knows of any alternative ways to do it, as my second example, but hopefully one which the API actually allows for? haha Thanks guys. I would post code, but its fairly complicated, a couple thousand lines for this specific class and it would probably take a couple days to explain with all the threading and event listeners and what not. I just need help with this 1 single thing. Please let me know if you have any questions.

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Why does this XSL fails to retrieve value from xml ?

- by Pavitar

Following is an extract of the XSL stylesheet that I have written. It says my '.xsl' is well formed but it somehow does not retrieve values from the xml,instead jus pastes the header and table headings. EDIT <?xml version="1.0" encoding="UTF-8"?> <xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:fo="http://www.w3.org/1999/XSL/Format" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:fn="http://www.w3.org/2005/xpath-functions"> <xsl:template match="/" > <html> <head> <title>GlenMark Pharma</title> </head> <h1 align="center"><font face="Monotype Corsiva" color="red">GlenMarkPharma</font></h1> <body> <table> <tbody> <tr> <th>ID</th> <th>ENAME</th> <th>Mobile</th> <th>EMAIL</th> <th>PWD</th> </tr> <xsl:for-each select="employees/employee"> <tr> <td><xsl:value-of select="@empID" /></td> <td><xsl:value-of select="name" /></td> <td><xsl:value-of select="mobile" /></td> <td><xsl:value-of select="email" /></td> <td><xsl:value-of select="pwd" /></td> </tr> </xsl:for-each> </tbody> </table> </body> </html> </xsl:template> </xsl:stylesheet> Here is my XML doc: <?xml version="1.0" encoding="UTF-8"?> <?xml-stylesheet type="text/xsl" href="MyfirstXsl.xsl"?> <!DOCTYPE employees SYSTEM "Mydtd.dtd"> <me:employees xmlns:me="[email protected]" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="[email protected] Mycomplex.xsd"> <me:employee empID="EMP101"> <me:name>Vicky</me:name> <me:mobile>9870582356</me:mobile> <me:email>[email protected]</me:email> <me:pwd>&defPWD;</me:pwd> </me:employee> </me:employees> I have also tried writing: <xsl:for-each select="employees/employee"> <tr> <td><xsl:value-of select="@empID" /></td> <td><xsl:value-of select="me:name" /></td> in the XSL since I have an alias to the namespace in my XML Doc.But it gives me an error of Invalid Pre-fix.I don't know what I'm doing wrong.

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Why might a System.String object not cache its hash code?

- by Dan Tao

A glance at the source code for string.GetHashCode using Reflector reveals the following (for mscorlib.dll version 4.0): public override unsafe int GetHashCode() { fixed (char* str = ((char*) this)) { char* chPtr = str; int num = 0x15051505; int num2 = num; int* numPtr = (int*) chPtr; for (int i = this.Length; i > 0; i -= 4) { num = (((num << 5) + num) + (num >> 0x1b)) ^ numPtr[0]; if (i <= 2) { break; } num2 = (((num2 << 5) + num2) + (num2 >> 0x1b)) ^ numPtr[1]; numPtr += 2; } return (num + (num2 * 0x5d588b65)); } } Now, I realize that the implementation of GetHashCode is not specified and is implementation-dependent, so the question "is GetHashCode implemented in the form of X or Y?" is not really answerable. I'm just curious about a few things: If Reflector has disassembled the DLL correctly and this is the implementation of GetHashCode (in my environment), am I correct in interpreting this code to indicate that a string object, based on this particular implementation, would not cache its hash code? Assuming the answer is yes, why would this be? It seems to me that the memory cost would be minimal (one more 32-bit integer, a drop in the pond compared to the size of the string itself) whereas the savings would be significant, especially in cases where, e.g., strings are used as keys in a hashtable-based collection like a Dictionary<string, [...]>. And since the string class is immutable, it isn't like the value returned by GetHashCode will ever even change. What could I be missing? UPDATE: In response to Andras Zoltan's closing remark: There's also the point made in Tim's answer(+1 there). If he's right, and I think he is, then there's no guarantee that a string is actually immutable after construction, therefore to cache the result would be wrong. Whoa, whoa there! This is an interesting point to make (and yes it's very true), but I really doubt that this was taken into consideration in the implementation of GetHashCode. The statement "therefore to cache the result would be wrong" implies to me that the framework's attitude regarding strings is "Well, they're supposed to be immutable, but really if developers want to get sneaky they're mutable so we'll treat them as such." This is definitely not how the framework views strings. It fully relies on their immutability in so many ways (interning of string literals, assignment of all zero-length strings to string.Empty, etc.) that, basically, if you mutate a string, you're writing code whose behavior is entirely undefined and unpredictable. I guess my point is that for the author(s) of this implementation to worry, "What if this string instance is modified between calls, even though the class as it is publicly exposed is immutable?" would be like for someone planning a casual outdoor BBQ to think to him-/herself, "What if someone brings an atomic bomb to the party?" Look, if someone brings an atom bomb, party's over.

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php sorting a seriously multidimensional array...

- by BigDogsBarking

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segmented controls mangled during initial transition animation

- by dLux

greetings and salutations folks, i'm relatively new to objective c & iphone programming, so bare with me if i've overlooked something obvious.. i created a simple app to play with the different transition animations, setting up a couple segmented controls and a slider.. (Flip/Curl), (left/right) | (up/down), (EaseInOut/EaseIn/EaseOut/Linear) i created a view controller class, and the super view controller switches between 2 instances of the sub class. as you can see from the following image, the first time switching to the 2nd instance, while the animation is occurring the segmented controls are mangled; i'd guess they haven't had enuff time to draw themselves completely.. http://img689.imageshack.us/img689/2320/mangledbuttonsduringtra.png they're fine once the animation is done, and any subsequent times.. if i specify cache:NO in the setAnimationTransition it helps, but there still seems to be some sort of progressive reveal for the text in the segmented controls; they still don't seem to be pre-rendered or initialized properly.. (and surely there's a way to do this while caching the view being transitioned to, since in this case the view isn't changing and should be cacheable.) i'm building my code based on a couple tutorials from a book, so i updated the didReceiveMemoryWarning to set the instanced view controllers to nil; when i invoke a memory warning in the simulator, i assume it's purging the other view, and it acts like a first transition after loading, the view being transitioned to appears just like the image above.. i guess it can't hurt to include the code (sorry if it's considered spamming), this is basically half of it, with a similar chunk following this in an else statement, for the case of the 2nd side being present, switching back to the 1st..: - (IBAction)switchViews:(id)sender { [UIView beginAnimations:@"Transition Animation" context:nil]; if (self.sideBViewController.view.superview == nil) // sideA is active, sideB is coming { if (self.sideBViewController == nil) { SideAViewController *sBController = [[SideAViewController alloc] initWithNibName:@"SideAViewController" bundle:nil]; self.sideBViewController = sBController; [sBController release]; } [UIView setAnimationDuration:sideAViewController.transitionDurationSlider.value]; if ([sideAViewController.transitionAnimation selectedSegmentIndex] == 0) { // flip: 0 == left, 1 == right if ([sideAViewController.flipDirection selectedSegmentIndex] == 0) [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:self.view cache:YES]; else [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES]; } else { // curl: 0 == up, 1 == down if ([sideAViewController.curlDirection selectedSegmentIndex] == 0) [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:self.view cache:YES]; else [UIView setAnimationTransition:UIViewAnimationTransitionCurlDown forView:self.view cache:YES]; } if ([sideAViewController.animationCurve selectedSegmentIndex] == 0) [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut]; else if ([sideAViewController.animationCurve selectedSegmentIndex] == 1) [UIView setAnimationCurve:UIViewAnimationCurveEaseIn]; else if ([sideAViewController.animationCurve selectedSegmentIndex] == 2) [UIView setAnimationCurve:UIViewAnimationCurveEaseOut]; else if ([sideAViewController.animationCurve selectedSegmentIndex] == 3) [UIView setAnimationCurve:UIViewAnimationCurveLinear]; [sideBViewController viewWillAppear:YES]; [sideAViewController viewWillDisappear:YES]; [sideAViewController.view removeFromSuperview]; [self.view insertSubview:sideBViewController.view atIndex:0]; [sideBViewController viewDidAppear:YES]; [sideAViewController viewDidDisappear:YES]; } any other tips or pointers about writing good clean code is also appreciated, i realize i still have a lot to learn.. thank u for ur time, -- d

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MVC using ODP.NET getting ORA-01840

- by sse

I am writing a simple MVC Application using ODP.NET. I am trying to call a Pl/Sql proc that inserts a record. Here is the simple Pl/Sql: procedure spAddCountry(pGisRecid in country.GISRECID%type, pCountryCode in country.COUNTRYCODE%type, pCountryName in country.COUNTRYNAME%type, pCurrencyCode in country.CURRENCYCODE%type, pEUTerritory in country.EUTERRITORY%type, pFatCAStatus in country.FATCASTATUS%type, pFATF in country.FATF%type, pFSCountryCode in country.COUNTRYCODE%type, pInsertedBy in country.INSERTEDBY%type, pInsertedOn in country.INSERTEDON%type, pLanguages in country.LANGUAGES%type, pNCCT in country.NCCT%type) is PRAGMA AUTONOMOUS_TRANSACTION; begin INSERT INTO COUNTRY (GISRECID, COUNTRYCODE, COUNTRYNAME, CURRENCYCODE, EUTERRITORY, FATCASTATUS, FATF, FSCOUNTRYCODE, INSERTEDBY, INSERTEDON, LANGUAGES, NCCT) VALUES(pGISRECID, pCOUNTRYCODE, pCOUNTRYNAME, pCURRENCYCODE, pEUTERRITORY, pFATCASTATUS, pFATF, pFSCOUNTRYCODE, pINSERTEDBY, pINSERTEDON, pLANGUAGES, pNCCT); Commit; end; I am having difficulty passing the date parameter, pInsertedOn, to the Stored Proc. I have verified that the web form retrieves the form data successfully and calls the AddCountry method below, which in turns calls the stored proc, spAddCountry, after populating all of the parms. Here is a snippet of the MVC C# code. I get the following exception: "ORA-01840 input value not long enough for date format". public void AddCountry(Country aCountry) //because the country object field names match the form field names they automatically get bound!! { string oradb = "Data Source=XYZ;User Id=XYZ;Password=xyz;"; OracleConnection conn = new OracleConnection(oradb); OracleCommand cmd = conn.CreateCommand(); cmd.CommandText = "tstpack.spAddCountry"; cmd.CommandType = CommandType.StoredProcedure; ... OracleParameter paramInsertedBy = new OracleParameter(); paramInsertedBy.ParameterName = "pInsertedBy"; paramInsertedBy.Value = aCountry.InsertedBy; cmd.Parameters.Add(paramInsertedBy); // CultureInfo ci = new CultureInfo("en-US"); OracleParameter paramInsertedOn = new OracleParameter(); paramInsertedOn.ParameterName = "pInsertedOn"; // paramInsertedOn.Value = DateTime.Now; //just testing to see if it's WebForm issue // paramInsertedOn.Value = Convert.ToDateTime(DateTime.Now.ToString(), ci); //flail! paramInsertedOn.Value = aCountry.InsertedOn; cmd.Parameters.Add(paramInsertedOn); ... conn.Open(); cmd.ExecuteNonQuery(); //CRASH! ORA-01840 conn.Close(); } Just to verify that the flow of the program is working, I tried removing the date parm "pInsertedOn" from the pl/sql and from the parm list above, and everything worked fine. I know I am going off of the rails with the date. Can someone tell me how to pass a date to Oracle from an MVC WebForm? Is there some sort of type cast needed? I would really appreciate an example too. Thanks so much! ps, I did try changing the parm type to Varchar2 in the Pl/Sql and doing some conversions myself in the Pl/Sql, the automatic MVC binder was getting in my way, forcing the property of paramInsertedOn.OracleType to DateTime. I tried forcing it to Varchar2, but no luck there either...

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Recommended integration mechanism for bi-directional, authenticated, encrypted connection in C clien

- by rcampbell

Let me first give an example. Imagine you have a single server running a JVM application. This server keeps a collection of N equations, once for each client: Client #1: 2x Client #2: 1 + y Client #3: z/4 This server includes an HTTP interface so that random visitors can type https://www.acme.com/client/3 int their browsers and see the latest evaluated result of z/4. The tricky part is that either the client or the server may change the variable value at any time, informing the other party immediately. More specifically, Client #3 - a C app - can initially tell the server that z = 20. An hour later that same client informs the server that z = 23. Likewise the server can later inform the client that z = 28. As caf pointed out in the comments, there can be a race condition when values are changed by the client and server simultaneously. The solution would be for both client and server to send the operation performed in their message, which would need to be executed by the other party. To keep things simple, let's limit the operations to (commutative) addition, allowing us to disregard message ordering. For example, the client seeds the server with z = 20: server:z=20, client:z=20 server sends {+3} message (so z=23 locally) & client sends {-2} message (so z=18 locally) at the exact same time server receives {-2} message at some point, adds to his local copy so z=21 client receives {+3} message at some point, adds to his local copy so z=21 As long as all messages are eventually evaluated by both parties, the correct answer will eventually be given to the users of the client and server since we limited ourselves to commutative operations (addition of 3 and -2). This does mean that both client and server can be returning incorrect answers in the time it takes for messages to be exchanged and processed. While undesirable, I believe this is unavoidable. Some possible implementations of this idea include: Open an encrypted, always on TCP socket connection for communication Pros: no additional infrastructure needed, client and server know immediately if there is a problem (disconnect) with the other party, fairly straightforward (except the the encryption), native support from both JVM and C platforms Cons: pretty low-level so you end up writing a lot yourself (protocol, delivery verification, retry-on-failure logic), probably have a lot of firewall headaches during client app installation Asynchronous messaging (ex: ActiveMQ) Pros: transactional, both C & Java integration, free up the client and server apps from needing retry logic or delivery verification, pretty straightforward encryption, easy extensibility via message filters/routers/etc Cons: need additional infrastructure (message server) which must never fail, Database or file system as asynchronous integration point Same pros/cons as above but messier RESTful Web Service Pros: simple, possible reuse of the server's existing REST API, SSL figures out the encryption problem for you (maybe use RSA key a la GitHub for authentication?) Cons: Client now needs to run a C HTTP REST server w/SSL, client and server need retry logic. Axis2 has both a Java and C version, but you may be limited to SOAP. What other techniques should I be evaluating? What real world experiences have you had with these mechanisms? Which do you recommend for this problem and why?

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Data munging and data import scripting

- by morpheous

I need to write some scripts to carry out some tasks on my server (running Ubuntu server 8.04 TLS). The tasks are to be run periodically, so I will be running the scripts as cron jobs. I have divided the tasks into "group A" and "group B" - because (in my mind at least), they are a bit different. Task Group A import data from a file and possibly reformat it - by reformatting, I mean doing things like santizing the data, possibly normalizing it and or running calculations on 'columns' of the data Import the munged data into a database. For now, I am mostly using mySQL for the vast majority of imports - although some files will be imported into a sqlLite database. Note: The files will be mostly text files, although some of the files are in a binary format (my own proprietary format, written by a C++ application I developed). Task Group B Extract data from the database Perform calculations on the data and either insert or update tables in the database. My coding experience is is primarily as a C/C++ developer, although I have been using PHP as well for the last 2 years or so. I am from a windows background so I am still finding my feet in the linux environment. My question is this - I need to write scripts to perform the tasks I described above. Although I suppose I could write a few C++ applications to be used in the shell scripts, I think it may be better to write them in a scripting language (maybe this is a flawed assumption?). My thinking is that it would be easier to modify thins in a script - no need to rebuild etc for changes to functionality. Additionally, C++ data munging in C++ tends to involve more lines of code than "natural" scripting languages such as Perl, Python etc. Assuming that the majority of people on here agree that scripting is the way to go, herein lies my dilema. Which scripting language to use to perform the tasks above (giving my background). My gut instinct tells me that Perl (shudder) would be the most obvious choice for performing all of the above tasks. BUT (and that is a big BUT). The mere mention of Perl makes my toes curl, as I had a very, very bag experience with it a while back. The syntax seems quite unnatural to me - despite how many times I have tried to learn it - so if possible, I would really like to give it a miss. PHP (which I already know), also am not sure is a good candidate for scripting on the CLI (I have not seen many examples on how to do this etc - so I may be wrong). The last thing I must mention is that IF I have to learn a new language in order to do this, I cannot afford (time constraint) to spend more than a day, in learning the key commands/features required in order to do this (I can always learn the details of the language later, once I have actually deployed the scripts). So, which scripting language would you recommend (PHP, Python, Perl, [insert your favorite here]) - and most importantly WHY?. Or, should I just stick to writing little C++ applications that I call in a shell script?. Lastly, if you have suggested a scripting language, can you please show with a FEW lines (Perl mongers - I'm looking in your direction [nothing to cryptic!] ;) ) how I can use the language you suggested to do what I want to do. Hopefully, the lines you present will convince me that it can be done easily and elegantly in the language you suggested.

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urllib2 misbehaving with dynamically loaded content

- by Sheena

Some Code headers = {} headers['user-agent'] = 'User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:16.0) Gecko/20100101 Firefox/16.0' headers['Accept'] = 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' headers['Accept-Language'] = 'en-gb,en;q=0.5' #headers['Accept-Encoding'] = 'gzip, deflate' request = urllib.request.Request(sURL, headers = headers) try: response = urllib.request.urlopen(request) except error.HTTPError as e: print('The server couldn\'t fulfill the request.') print('Error code: {0}'.format(e.code)) except error.URLError as e: print('We failed to reach a server.') print('Reason: {0}'.format(e.reason)) else: f = open('output/{0}.html'.format(sFileName),'w') f.write(response.read().decode('utf-8')) A url http://groupon.cl/descuentos/santiago-centro The situation Here's what I did: enable javascript in browser open url above and keep an eye on the console disable javascript repeat step 2 use urllib2 to grab the webpage and save it to a file enable javascript open the file with browser and observe console repeat 7 with javascript off results In step 2 I saw that a whole lot of the page content was loaded dynamically using ajax. So the HTML that arrived was a sort of skeleton and ajax was used to fill in the gaps. This is fine and not at all surprising Since the page should be seo friendly it should work fine without js. in step 4 nothing happens in the console and the skeleton page loads pre-populated rendering the ajax unnecessary. This is also completely not confusing in step 7 the ajax calls are made but fail. this is also ok since the urls they are using are not local, the calls are thus broken. The page looks like the skeleton. This is also great and expected. in step 8: no ajax calls are made and the skeleton is just a skeleton. I would have thought that this should behave very much like in step 4 question What I want to do is use urllib2 to grab the html from step 4 but I cant figure out how. What am I missing and how could I pull this off? To paraphrase If I was writing a spider I would want to be able to grab plain ol' HTML (as in that which resulted in step 4). I dont want to execute ajax stuff or any javascript at all. I don't want to populate anything dynamically. I just want HTML. The seo friendly site wants me to get what I want because that's what seo is all about. How would one go about getting plain HTML content given the situation I outlined? To do it manually I would turn off js, navigate to the page and copy the html. I want to automate this. stuff I've tried I used wireshark to look at packet headers and the GETs sent off from my pc in steps 2 and 4 have the same headers. Reading about SEO stuff makes me think that this is pretty normal otherwise techniques such as hijax wouldn't be used. Here are the headers my browser sends: Host: groupon.cl User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:16.0) Gecko/20100101 Firefox/16.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-gb,en;q=0.5 Accept-Encoding: gzip, deflate Connection: keep-alive Here are the headers my script sends: Accept-Encoding: identity Host: groupon.cl Accept-Language: en-gb,en;q=0.5 Connection: close Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 User-Agent: User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:16.0) Gecko/20100101 Firefox/16.0 The differences are: my script has Connection = close instead of keep-alive. I can't see how this would cause a problem my script has Accept-encoding = identity. This might be the cause of the problem. I can't really see why the host would use this field to determine the user-agent though. If I change encoding to match the browser request headers then I have trouble decoding it. I'm working on this now... watch this space, I'll update the question as new info comes up

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How to map code points to unicode characters depending on the font used?

- by Alex Schröder

The client prints labels and has been using a set of symbolic (?) fonts to do this. The application uses a single byte database (Oracle with Latin-1). The old application I am replacing was not Unicode aware. It somehow did OK. The replacement application I am writing is supposed to handle the old data. The symbols picked from the charmap application often map to particular Unicode characters, but sometimes they don't. What looks like the Moon using the LAB3 font, for example, is in fact U+2014 (EM DASH). When users paste this character into a Swing text field, the character has the code point 8212. It was "moved" into the Private Use Area (by Windows? Java?). When saving this character to the database, Oracle decides that it cannot be safely encoded and replaces it with the dreaded ¿. Thus, I started shifting the characters by 8000: -= 8000 when saving, += 8000 when displaying the field. Unfortunately I discovered that other characters were not shifted by the same amount. In one particular font, for example, ž has the code point 382, so I shifted it by +/-256 to "fix" it. By now I'm dreading the discovery of more strange offsets and I wonder: Can I get at this mapping using Java? Perhaps the TTF font has a list of the 255 glyphs it encodes and what Unicode characters those correspond to and I can do it "right"? Right now I'm using the following kludge: static String fromDatabase(String str, String fontFamily) { if (str != null && fontFamily != null) { Font font = new Font(fontFamily, Font.PLAIN, 1); boolean changed = false; char[] chars = str.toCharArray(); for (int i = 0; i < chars.length; i++) { if (font.canDisplay(chars[i] + 0xF000)) { // WE8MSWIN1252 + WinXP chars[i] += 0xF000; changed = true; } else if (chars[i] >= 128 && font.canDisplay(chars[i] + 8000)) { // WE8ISO8859P1 + WinXP chars[i] += 8000; changed = true; } else if (font.canDisplay(chars[i] + 256)) { // ž in LAB1 Eastern = 382 chars[i] += 256; changed = true; } } if (changed) str = new String(chars); } return str; } static String toDatabase(String str, String fontFamily) { if (str != null && fontFamily != null) { boolean changed = false; char[] chars = str.toCharArray(); for (int i = 0; i < chars.length; i++) { int chr = chars[i]; if (chars[i] > 0xF000) { // WE8MSWIN1252 + WinXP chars[i] -= 0xF000; changed = true; } else if (chars[i] > 8000) { // WE8ISO8859P1 + WinXP chars[i] = (char) (chars[i] - 8000); changed = true; } else if (chars[i] > 256) { // ž in LAB1 Eastern = 382 chars[i] = (char) (chars[i] - 256); changed = true; } } if (changed) return new String(chars); } return str; }

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how can udp data can passed through RS232 in ansi c?

- by moon

i want to transmit and receive data on RS232 using udp and i want to know about techniques which allow me to transmit and receive data on a faster rate and also no lose of data is there? thanx in advance. i have tried but need improvements if possible #include <stdio.h> #include <dos.h> #include<string.h> #include<conio.h> #include<iostream.h> #include<stdlib.h> #define PORT1 0x3f8 void main() { int c,ch,choice,i,a=0; char filename[30],filename2[30],buf; FILE *in,*out; clrscr(); while(1){ outportb(PORT1+0,0x03); outportb(PORT1+1,0); outportb(PORT1+3,0x03); outportb(PORT1+2,0xc7); outportb(PORT1+4,0x0b); cout<<"\n==============================================================="; cout<<"\n\t*****Serial Communication By BADR-U-ZAMAN******\nCommunication between two computers By serial port"; cout<<"\nPlease select\n[1]\tFor sending file \n[2]\tFor receiving file \n[3]\tTo exit\n"; cout<<"=================================================================\n"; cin>>choice; if(choice==1) { strcpy(filename,"C:\\TC\\BIN\\badr.cpp"); cout<<filename; for(i=0;i<=strlen(filename);i++) outportb(PORT1,filename[i]); in=fopen(filename,"r"); if (in==NULL) { cout<<"cannot open a file"; a=1; } if(a!=1) cout<<"\n\nFile sending.....\n\n"; while(!feof(in)) { buf=fgetc(in); cout<<buf; outportb(PORT1,buf); delay(5); } } else { if(choice==3) exit(0); i=0; buf='a'; while(buf!=NULL) { c=inportb(PORT1+5); if(c&1) { buf=inportb(PORT1); filename2[i]=buf; i++; } } out=fopen(filename2,"t"); cout<<"\n Filename received:"<<filename[2]; cout<<"\nReading from the port..."; cout<<"writing to file"<<filename2; do { c=inportb(PORT1+5); if(c&1) { buf=inportb(PORT1); cout<<buf; fputc(buf,out); delay(5); } if(kbhit()) { ch=getch(); } }while(ch!=27); } getch(); } }

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Generating cache file for Twitter rss feed

- by Kerri

I'm working on a site with a simple php-generated twitter box with user timeline tweets pulled from the user_timeline rss feed, and cached to a local file to cut down on loads, and as backup for when twitter goes down. I based the caching on this: http://snipplr.com/view/8156/twitter-cache/. It all seemed to be working well yesterday, but today I discovered the cache file was blank. Deleting it then loading again generated a fresh file. The code I'm using is below. I've edited it to try to get it to work with what I was already using to display the feed and probably messed something crucial up. The changes I made are the following (and I strongly believe that any of these could be the cause): - Revised the time difference code (the linked example seemed to use a custom function that wasn't included in the code) Removed the "serialize" function from the "fwrites". This is purely because I couldn't figure out how to unserialize once I loaded it in the display code. I truthfully don't understand the role that serialize plays or how it works, so I'm sure I should have kept it in. If that's the case I just need to understand where/how to deserialize in the second part of the code so that it can be parsed. Removed the $rss variable in favor of just loading up the cache file in my original tweet display code. So, here are the relevant parts of the code I used: <?php $feedURL = "http://twitter.com/statuses/user_timeline/#######.rss"; // START CACHING $cache_file = dirname(__FILE__).'/cache/twitter_cache.rss'; // Start with the cache if(file_exists($cache_file)){ $mtime = (strtotime("now") - filemtime($cache_file)); if($mtime > 600) { $cache_rss = file_get_contents('http://twitter.com/statuses/user_timeline/75168146.rss'); $cache_static = fopen($cache_file, 'wb'); fwrite($cache_static, $cache_rss); fclose($cache_static); } echo ""; } else { $cache_rss = file_get_contents('http://twitter.com/statuses/user_timeline/#######.rss'); $cache_static = fopen($cache_file, 'wb'); fwrite($cache_static, $cache_rss); fclose($cache_static); } //END CACHING //START DISPLAY $doc = new DOMDocument(); $doc->load($cache_file); $arrFeeds = array(); foreach ($doc->getElementsByTagName('item') as $node) { $itemRSS = array ( 'title' => $node->getElementsByTagName('title')->item(0)->nodeValue, 'date' => $node->getElementsByTagName('pubDate')->item(0)->nodeValue ); array_push($arrFeeds, $itemRSS); } // the rest of the formatting and display code.... } ?> ETA 6/17 Nobody can help…? I'm thinking it has something to do with writing a blank cache file over a good one when twitter is down, because otherwise I imagine that this should be happening every ten minutes when the cache file is overwritten again, but it doesn't happen that frequently. I made the following change to the part where it checks how old the file is to overwrite it: $cache_rss = file_get_contents('http://twitter.com/statuses/user_timeline/75168146.rss'); if($mtime > 600 && $cache_rss != ''){ $cache_static = fopen($cache_file, 'wb'); fwrite($cache_static, $cache_rss); fclose($cache_static); } …so now, it will only write the file if it's over ten minutes old and there's actual content retrieved from the rss page. Do you think this will work?

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R: extracting "clean" UTF-8 text from a web page scraped with RCurl

- by SlowLearner

Using R, I am trying to scrape a web page save the text, which is in Japanese, to a file. Ultimately this needs to be scaled to tackle hundreds of pages on a daily basis. I already have a workable solution in Perl, but I am trying to migrate the script to R to reduce the cognitive load of switching between multiple languages. So far I am not succeeding. Related questions seem to be this one on saving csv files and this one on writing Hebrew to a HTML file. However, I haven't been successful in cobbling together a solution based on the answers there. The pages are from Yahoo! Japan Finance and my Perl code that looks like this. use strict; use HTML::Tree; use LWP::Simple; #use Encode; use utf8; binmode STDOUT, ":utf8"; my @arr_links = (); $arr_links[1] = "http://stocks.finance.yahoo.co.jp/stocks/detail/?code=7203"; $arr_links[2] = "http://stocks.finance.yahoo.co.jp/stocks/detail/?code=7201"; foreach my $link (@arr_links){ $link =~ s/"//gi; print("$link\n"); my $content = get($link); my $tree = HTML::Tree->new(); $tree->parse($content); my $bar = $tree->as_text; open OUTFILE, ">>:utf8", join("","c:/", substr($link, -4),"_perl.txt") || die; print OUTFILE $bar; } This Perl script produces a CSV file that looks like the screenshot below, with proper kanji and kana that can be mined and manipulated offline: My R code, such as it is, looks like the following. The R script is not an exact duplicate of the Perl solution just given, as it doesn't strip out the HTML and leave the text (this answer suggests an approach using R but it doesn't work for me in this case) and it doesn't have the loop and so on, but the intent is the same. require(RCurl) require(XML) links <- list() links[1] <- "http://stocks.finance.yahoo.co.jp/stocks/detail/?code=7203" links[2] <- "http://stocks.finance.yahoo.co.jp/stocks/detail/?code=7201" txt <- getURL(links, .encoding = "UTF-8") Encoding(txt) <- "bytes" write.table(txt, "c:/geturl_r.txt", quote = FALSE, row.names = FALSE, sep = "\t", fileEncoding = "UTF-8") This R script generates the output shown in the screenshot below. Basically rubbish. I assume that there is some combination of HTML, text and file encoding that will allow me to generate in R a similar result to that of the Perl solution but I cannot find it. The header of the HTML page I'm trying to scrape says the chartset is utf-8 and I have set the encoding in the getURL call and in the write.table function to utf-8, but this alone isn't enough. The question How can I scrape the above web page using R and save the text as CSV in "well-formed" Japanese text rather than something that looks like line noise? Edit: I have added a further screenshot to show what happens when I omit the Encoding step. I get what look like Unicode codes, but not the graphical representation of the characters. So it may be some kind of locale-related issue, but in the exact same locale the Perl script does provide useful output. So this is still puzzling.

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Why does my performance slow to a crawl I move methods into a base class?

- by Juliet

I'm writing different implementations of immutable binary trees in C#, and I wanted my trees to inherit some common methods from a base class. However, I find. I have lots of binary tree data structures to implement, and I wanted move some common methods into in a base binary tree class. Unfortunately, classes which derive from the base class are abysmally slow. Non-derived classes perform adequately. Here are two nearly identical implementations of an AVL tree to demonstrate: AvlTree: http://pastebin.com/V4WWUAyT DerivedAvlTree: http://pastebin.com/PussQDmN The two trees have the exact same code, but I've moved the DerivedAvlTree.Insert method in base class. Here's a test app: using System; using System.Collections.Generic; using System.Diagnostics; using System.Linq; using Juliet.Collections.Immutable; namespace ConsoleApplication1 { class Program { const int VALUE_COUNT = 5000; static void Main(string[] args) { var avlTreeTimes = TimeIt(TestAvlTree); var derivedAvlTreeTimes = TimeIt(TestDerivedAvlTree); Console.WriteLine("avlTreeTimes: {0}, derivedAvlTreeTimes: {1}", avlTreeTimes, derivedAvlTreeTimes); } static double TimeIt(Func<int, int> f) { var seeds = new int[] { 314159265, 271828183, 231406926, 141421356, 161803399, 266514414, 15485867, 122949829, 198491329, 42 }; var times = new List<double>(); foreach (int seed in seeds) { var sw = Stopwatch.StartNew(); f(seed); sw.Stop(); times.Add(sw.Elapsed.TotalMilliseconds); } // throwing away top and bottom results times.Sort(); times.RemoveAt(0); times.RemoveAt(times.Count - 1); return times.Average(); } static int TestAvlTree(int seed) { var rnd = new System.Random(seed); var avlTree = AvlTree<double>.Create((x, y) => x.CompareTo(y)); for (int i = 0; i < VALUE_COUNT; i++) { avlTree = avlTree.Insert(rnd.NextDouble()); } return avlTree.Count; } static int TestDerivedAvlTree(int seed) { var rnd = new System.Random(seed); var avlTree2 = DerivedAvlTree<double>.Create((x, y) => x.CompareTo(y)); for (int i = 0; i < VALUE_COUNT; i++) { avlTree2 = avlTree2.Insert(rnd.NextDouble()); } return avlTree2.Count; } } } AvlTree: inserts 5000 items in 121 ms DerivedAvlTree: inserts 5000 items in 2182 ms My profiler indicates that the program spends an inordinate amount of time in BaseBinaryTree.Insert. Anyone whose interested can see the EQATEC log file I've created with the code above (you'll need EQATEC profiler to make sense of file). I really want to use a common base class for all of my binary trees, but I can't do that if performance will suffer. What causes my DerivedAvlTree to perform so badly, and what can I do to fix it?

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Dynamically loading modules in Python (+ multi processing question)

- by morpheous

I am writing a Python package which reads the list of modules (along with ancillary data) from a configuration file. I then want to iterate through each of the dynamically loaded modules and invoke a do_work() function in it which will spawn a new process, so that the code runs ASYNCHRONOUSLY in a separate process. At the moment, I am importing the list of all known modules at the beginning of my main script - this is a nasty hack I feel, and is not very flexible, as well as being a maintenance pain. This is the function that spawns the processes. I will like to modify it to dynamically load the module when it is encountered. The key in the dictionary is the name of the module containing the code: def do_work(work_info): for (worker, dataset) in work_info.items(): #import the module defined by variable worker here... # [Edit] NOT using threads anymore, want to spawn processes asynchronously here... #t = threading.Thread(target=worker.do_work, args=[dataset]) # I'll NOT dameonize since spawned children need to clean up on shutdown # Since the threads will be holding resources #t.daemon = True #t.start() Question 1 When I call the function in my script (as written above), I get the following error: AttributeError: 'str' object has no attribute 'do_work' Which makes sense, since the dictionary key is a string (name of the module to be imported). When I add the statement: import worker before spawning the thread, I get the error: ImportError: No module named worker This is strange, since the variable name rather than the value it holds are being used - when I print the variable, I get the value (as I expect) whats going on? Question 2 As I mentioned in the comments section, I realize that the do_work() function written in the spawned children needs to cleanup after itself. My understanding is to write a clean_up function that is called when do_work() has completed successfully, or an unhandled exception is caught - is there anything more I need to do to ensure resources don't leak or leave the OS in an unstable state? Question 3 If I comment out the t.daemon flag statement, will the code stil run ASYNCHRONOUSLY?. The work carried out by the spawned children are pretty intensive, and I don't want to have to be waiting for one child to finish before spawning another child. BTW, I am aware that threading in Python is in reality, a kind of time sharing/slicing - thats ok Lastly is there a better (more Pythonic) way of doing what I'm trying to do? [Edit] After reading a little more about Pythons GIL and the threading (ahem - hack) in Python, I think its best to use separate processes instead (at least IIUC, the script can take advantage of multiple processes if they are available), so I will be spawning new processes instead of threads. I have some sample code for spawning processes, but it is a bit trivial (using lambad functions). I would like to know how to expand it, so that it can deal with running functions in a loaded module (like I am doing above). This is a snippet of what I have: def do_mp_bench(): q = mp.Queue() # Not only thread safe, but "process safe" p1 = mp.Process(target=lambda: q.put(sum(range(10000000)))) p2 = mp.Process(target=lambda: q.put(sum(range(10000000)))) p1.start() p2.start() r1 = q.get() r2 = q.get() return r1 + r2 How may I modify this to process a dictionary of modules and run a do_work() function in each loaded module in a new process?

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JPA2 adding referential contraint to table complicates criteria query with lazy fetch, need advice

- by Quaternion

Following is a lot of writing for what I feel is a pretty simple issue. Root of issue is my ignorance, not looking so much for code but advice. Table: Ininvhst (Inventory-schema inventory history) column ihtran (inventory history transfer code) using an old entity mapping I have: @Basic(optional = false) @Column(name = "IHTRAN") private String ihtran; ihtran is really a foreign key to table Intrnmst ("Inventory Transfer Master" which contains a list of "transfer codes"). This was not expressed in the database so placed a referential constraint on Ininvhst re-generating JPA2 entity classes produced: @JoinColumn(name = "IHTRAN", referencedColumnName = "TMCODE", nullable = false) @ManyToOne(optional = false) private Intrnmst intrnmst; Now previously I was using JPA2 to select the records/(Ininvhst entities) from the Ininvhst table where "ihtran" was one of a set of values. I used in.value() to do this... here is a snippet: cq = cb.createQuery(Ininvhst.class); ... In in = cb.in(transactionType); //Get in expression for transacton types for (String s : transactionTypes) { //has a value in = in.value(s);//check if the strings we are looking for exist in the transfer master } predicateList.add(in); My issue is that the Ininvhst used to contain a string called ihtran but now it contains Ininvhst... So I now need a path expression: this.predicateList = new ArrayList<Predicate>(); if (transactionTypes != null && transactionTypes.size() > 0) { //list of strings has some values Path<Intrnmst> intrnmst = root.get(Ininvhst_.intrnmst); //get transfermaster from Ininvhst Path<String> transactionType = intrnmst.get(Intrnmst_.tmcode); //get transaction types from transfer master In<String> in = cb.in(transactionType); //Get in expression for transacton types for (String s : transactionTypes) { //has a value in = in.value(s);//check if the strings we are looking for exist in the transfer master } predicateList.add(in); } Can I add ihtran back into the entity along with a join column that is both references "IHTRAN"? Or should I use a projection to somehow return Ininvhst along with the ihtran string which is now part of the Intrnmst entity. Or should I use a projection to return Ininvhst and somehow limit Intrnmst just just the ihtran string. Further information: I am using the resulting list of selected Ininvhst objects in a web application, the class which contains the list of Ininvhst objects is transformed into a json object. There are probably quite a few serialization methods that would navigate the object graph the problem is that my current fetch strategy is lazy so it hits the join entity (Intrnmst intrnmst) and there is no Entity Manager available at that point. At this point I have prevented the object from serializing the join column but now I am missing a critical piece of data. I think I've said too much but not knowing enough I don't know what you JPA experts need. What I would like is my original object to have both a string object and be able to join on the same column (ihtran) and have it as a string too, but if this isn't possible or advisable I want to hear what I should do and why. Pseudo code/English is more than fine.

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Resumable upload from Java client to Grails web application?

- by dersteps

After almost 2 workdays of Googling and trying several different possibilities I found throughout the web, I'm asking this question here, hoping that I might finally get an answer. First of all, here's what I want to do: I'm developing a client and a server application with the purpose of exchanging a lot of large files between multiple clients on a single server. The client is developed in pure Java (JDK 1.6), while the web application is done in Grails (2.0.0). As the purpose of the client is to allow users to exchange a lot of large files (usually about 2GB each), I have to implement it in a way, so that the uploads are resumable, i.e. the users are able to stop and resume uploads at any time. Here's what I did so far: I actually managed to do what I wanted to do and stream large files to the server while still being able to pause and resume uploads using raw sockets. I would send a regular request to the server (using Apache's HttpClient library) to get the server to send me a port that was free for me to use, then open a ServerSocket on the server and connect to that particular socket from the client. Here's the problem with that: Actually, there are at least two problems with that: I open those ports myself, so I have to manage open and used ports myself. This is quite error-prone. I actually circumvent Grails' ability to manage a huge amount of (concurrent) connections. Finally, here's what I'm supposed to do now and the problem: As the problems I mentioned above are unacceptable, I am now supposed to use Java's URLConnection/HttpURLConnection classes, while still sticking to Grails. Connecting to the server and sending simple requests is no problem at all, everything worked fine. The problems started when I tried to use the streams (the connection's OutputStream in the client and the request's InputStream in the server). Opening the client's OutputStream and writing data to it is as easy as it gets. But reading from the request's InputStream seems impossible to me, as that stream is always empty, as it seems. Example Code Here's an example of the server side (Groovy controller): def test() { InputStream inStream = request.inputStream if(inStream != null) { int read = 0; byte[] buffer = new byte[4096]; long total = 0; println "Start reading" while((read = inStream.read(buffer)) != -1) { println "Read " + read + " bytes from input stream buffer" //<-- this is NEVER called } println "Reading finished" println "Read a total of " + total + " bytes" // <-- 'total' will always be 0 (zero) } else { println "Input Stream is null" // <-- This is NEVER called } } This is what I did on the client side (Java class): public void connect() { final URL url = new URL("myserveraddress"); final byte[] message = "someMessage".getBytes(); // Any byte[] - will be a file one day HttpURLConnection connection = url.openConnection(); connection.setRequestMethod("GET"); // other methods - same result // Write message DataOutputStream out = new DataOutputStream(connection.getOutputStream()); out.writeBytes(message); out.flush(); out.close(); // Actually connect connection.connect(); // is this placed correctly? // Get response BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream())); String line = null; while((line = in.readLine()) != null) { System.out.println(line); // Prints the whole server response as expected } in.close(); } As I mentioned, the problem is that request.inputStream always yields an empty InputStream, so I am never able to read anything from it (of course). But as that is exactly what I'm trying to do (so I can stream the file to be uploaded to the server, read from the InputStream and save it to a file), this is rather disappointing. I tried different HTTP methods, different data payloads, and also rearranged the code over and over again, but did not seem to be able to solve the problem. What I hope to find I hope to find a solution to my problem, of course. Anything is highly appreciated: hints, code snippets, library suggestions and so on. Maybe I'm even having it all wrong and need to go in a totally different direction. So, how can I implement resumable file uploads for rather large (binary) files from a Java client to a Grails web application without manually opening ports on the server side?

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IOException during blocking network NIO in JDK 1.7

- by Bass

I'm just learning NIO, and here's the short example I've written to test how a blocking NIO can be interrupted: class TestBlockingNio { private static final boolean INTERRUPT_VIA_THREAD_INTERRUPT = true; /** * Prevent the socket from being GC'ed */ static Socket socket; private static SocketChannel connect(final int port) { while (true) { try { final SocketChannel channel = SocketChannel.open(new InetSocketAddress(port)); channel.configureBlocking(true); return channel; } catch (final IOException ioe) { try { Thread.sleep(1000); } catch (final InterruptedException ie) { } continue; } } } private static byte[] newBuffer(final int length) { final byte buffer[] = new byte[length]; for (int i = 0; i < length; i++) { buffer[i] = (byte) 'A'; } return buffer; } public static void main(final String args[]) throws IOException, InterruptedException { final int portNumber = 10000; new Thread("Reader") { public void run() { try { final ServerSocket serverSocket = new ServerSocket(portNumber); socket = serverSocket.accept(); /* * Fully ignore any input from the socket */ } catch (final IOException ioe) { ioe.printStackTrace(); } } }.start(); final SocketChannel channel = connect(portNumber); final Thread main = Thread.currentThread(); final Thread interruptor = new Thread("Inerruptor") { public void run() { System.out.println("Press Enter to interrupt I/O "); while (true) { try { System.in.read(); } catch (final IOException ioe) { ioe.printStackTrace(); } System.out.println("Interrupting..."); if (INTERRUPT_VIA_THREAD_INTERRUPT) { main.interrupt(); } else { try { channel.close(); } catch (final IOException ioe) { System.out.println(ioe.getMessage()); } } } } }; interruptor.setDaemon(true); interruptor.start(); final ByteBuffer buffer = ByteBuffer.allocate(32768); int i = 0; try { while (true) { buffer.clear(); buffer.put(newBuffer(buffer.capacity())); buffer.flip(); channel.write(buffer); System.out.print('X'); if (++i % 80 == 0) { System.out.println(); Thread.sleep(100); } } } catch (final ClosedByInterruptException cbie) { System.out.println("Closed via Thread.interrupt()"); } catch (final AsynchronousCloseException ace) { System.out.println("Closed via Channel.close()"); } } } In the above example, I'm writing to a SocketChannel, but noone is reading from the other side, so eventually the write operation hangs. This example works great when run by JDK-1.6, with the following output: Press Enter to interrupt I/O XXXX Interrupting... Closed via Thread.interrupt() — meaning that only 128k of data was written to the TCP socket's buffer. When run by JDK-1.7 (1.7.0_25-b15 and 1.7.0-u40-b37), however, the very same code bails out with an IOException: Press Enter to interrupt I/O XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXX Exception in thread "main" java.io.IOException: Broken pipe at sun.nio.ch.FileDispatcherImpl.write0(Native Method) at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:47) at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:93) at sun.nio.ch.IOUtil.write(IOUtil.java:65) at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:487) at com.example.TestBlockingNio.main(TestBlockingNio.java:109) Can anyone explain this different behaviour?

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Decomposing a rotation matrix

- by DeadMG

I have a rotation matrix. How can I get the rotation around a specified axis contained within this matrix? Edit: It's a 3D matrix (4x4), and I want to know how far around a predetermined (not contained) axis the matrix rotates. I can already decompose the matrix but D3DX will only give the entire matrix as one rotation around one axis, whereas I need to split the matrix up into angle of rotation around an already-known axis, and the rest. Sample code and brief problem description: D3DXMATRIX CameraRotationMatrix; D3DXVECTOR3 CameraPosition; //D3DXVECTOR3 CameraRotation; inline D3DXMATRIX GetRotationMatrix() { return CameraRotationMatrix; } inline void TranslateCamera(float x, float y, float z) { D3DXVECTOR3 rvec, vec(x, y, z); #pragma warning(disable : 4238) D3DXVec3TransformNormal(&rvec, &vec, &GetRotationMatrix()); #pragma warning(default : 4238) CameraPosition += rvec; RecomputeVPMatrix(); } inline void RotateCamera(float x, float y, float z) { D3DXVECTOR3 RotationRequested(x, y, z); D3DXVECTOR3 XAxis, YAxis, ZAxis; D3DXMATRIX rotationx, rotationy, rotationz; XAxis = D3DXVECTOR3(1, 0, 0); YAxis = D3DXVECTOR3(0, 1, 0); ZAxis = D3DXVECTOR3(0, 0, 1); #pragma warning(disable : 4238) D3DXVec3TransformNormal(&XAxis, &XAxis, &GetRotationMatrix()); D3DXVec3TransformNormal(&YAxis, &YAxis, &GetRotationMatrix()); D3DXVec3TransformNormal(&ZAxis, &ZAxis, &GetRotationMatrix()); #pragma warning(default : 4238) D3DXMatrixIdentity(&rotationx); D3DXMatrixIdentity(&rotationy); D3DXMatrixIdentity(&rotationz); D3DXMatrixRotationAxis(&rotationx, &XAxis, RotationRequested.x); D3DXMatrixRotationAxis(&rotationy, &YAxis, RotationRequested.y); D3DXMatrixRotationAxis(&rotationz, &ZAxis, RotationRequested.z); CameraRotationMatrix *= rotationz; CameraRotationMatrix *= rotationy; CameraRotationMatrix *= rotationx; RecomputeVPMatrix(); } inline void RecomputeVPMatrix() { D3DXMATRIX ProjectionMatrix; D3DXMatrixPerspectiveFovLH( &ProjectionMatrix, FoV, (float)D3DDeviceParameters.BackBufferWidth / (float)D3DDeviceParameters.BackBufferHeight, FarPlane, NearPlane ); D3DXVECTOR3 CamLookAt; D3DXVECTOR3 CamUpVec; #pragma warning(disable : 4238) D3DXVec3TransformNormal(&CamLookAt, &D3DXVECTOR3(1, 0, 0), &GetRotationMatrix()); D3DXVec3TransformNormal(&CamUpVec, &D3DXVECTOR3(0, 1, 0), &GetRotationMatrix()); #pragma warning(default : 4238) D3DXMATRIX ViewMatrix; #pragma warning(disable : 4238) D3DXMatrixLookAtLH(&ViewMatrix, &CameraPosition, &(CamLookAt + CameraPosition), &CamUpVec); #pragma warning(default : 4238) ViewProjectionMatrix = ViewMatrix * ProjectionMatrix; D3DVIEWPORT9 vp = { 0, 0, D3DDeviceParameters.BackBufferWidth, D3DDeviceParameters.BackBufferHeight, 0, 1 }; D3DDev->SetViewport(&vp); } Effectively, after a certain time, when RotateCamera is called, it begins to rotate in the relative X axis- even though constant zero is passed in for that request when responding to mouse input, so I know that when moving the mouse, the camera should not roll at all. I tried spamming 0,0,0 requests and saw no change (one per frame at 1500 frames per second), so I'm fairly sure that I'm not seeing FP error or matrix accumulation error. I tried writing a RotateCameraYZ function and stripping all X-axis from the function. I've spent several days trying to discover why this is the case, and eventually decided on just hacking around it. Just for reference, I've seen some diagrams on Wikipedia, and I actually have a relatively strange axis layout, which is Y axis up, but X axis forwards and Z axis right, so Y axis yaw, Z axis pitch, X axis roll.

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Lockless queue implementation ends up having a loop under stress

- by Fozi

I have lockless queues written in C in form of a linked list that contains requests from several threads posted to and handled in a single thread. After a few hours of stress I end up having the last request's next pointer pointing to itself, which creates an endless loop and locks up the handling thread. The application runs (and fails) on both Linux and Windows. I'm debugging on Windows, where my COMPARE_EXCHANGE_PTR maps to InterlockedCompareExchangePointer. This is the code that pushes a request to the head of the list, and is called from several threads: void push_request(struct request * volatile * root, struct request * request) { assert(request); do { request->next = *root; } while(COMPARE_EXCHANGE_PTR(root, request, request->next) != request->next); } This is the code that gets a request from the end of the list, and is only called by a single thread that is handling them: struct request * pop_request(struct request * volatile * root) { struct request * volatile * p; struct request * request; do { p = root; while(*p && (*p)->next) p = &(*p)->next; // <- loops here request = *p; } while(COMPARE_EXCHANGE_PTR(p, NULL, request) != request); assert(request->next == NULL); return request; } Note that I'm not using a tail pointer because I wanted to avoid the complication of having to deal with the tail pointer in push_request. However I suspect that the problem might be in the way I find the end of the list. There are several places that push a request into the queue, but they all look generaly like this: // device->requests is defined as struct request * volatile requests; struct request * request = malloc(sizeof(struct request)); if(request) { // fill out request fields push_request(&device->requests, request); sem_post(device->request_sem); } The code that handles the request is doing more than that, but in essence does this in a loop: if(sem_wait_timeout(device->request_sem, timeout) == sem_success) { struct request * request = pop_request(&device->requests); // handle request free(request); } I also just added a function that is checking the list for duplicates before and after each operation, but I'm afraid that this check will change the timing so that I will never encounter the point where it fails. (I'm waiting for it to break as I'm writing this.) When I break the hanging program the handler thread loops in pop_request at the marked position. I have a valid list of one or more requests and the last one's next pointer points to itself. The request queues are usually short, I've never seen more then 10, and only 1 and 3 the two times I could take a look at this failure in the debugger. I thought this through as much as I could and I came to the conclusion that I should never be able to end up with a loop in my list unless I push the same request twice. I'm quite sure that this never happens. I'm also fairly sure (although not completely) that it's not the ABA problem. I know that I might pop more than one request at the same time, but I believe this is irrelevant here, and I've never seen it happening. (I'll fix this as well) I thought long and hard about how I can break my function, but I don't see a way to end up with a loop. So the question is: Can someone see a way how this can break? Can someone prove that this can not? Eventually I will solve this (maybe by using a tail pointer or some other solution - locking would be a problem because the threads that post should not be locked, I do have a RW lock at hand though) but I would like to make sure that changing the list actually solves my problem (as opposed to makes it just less likely because of different timing).

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Listening for TCP and UDP requests on the same port

- by user339328

I am writing a Client/Server set of programs Depending on the operation requested by the client, I use make TCP or UDP request. Implementing the client side is straight-forward, since I can easily open connection with any protocol and send the request to the server-side. On the servers-side, on the other hand, I would like to listen both for UDP and TCP connections on the same port. Moreover, I like the the server to open new thread for each connection request. I have adopted the approach explained in: link text I have extended this code sample by creating new threads for each TCP/UDP request. This works correctly if I use TCP only, but it fails when I attempt to make UDP bindings. Please give me any suggestion how can I correct this. tnx Here is the Server Code: public class Server { public static void main(String args[]) { try { int port = 4444; if (args.length > 0) port = Integer.parseInt(args[0]); SocketAddress localport = new InetSocketAddress(port); // Create and bind a tcp channel to listen for connections on. ServerSocketChannel tcpserver = ServerSocketChannel.open(); tcpserver.socket().bind(localport); // Also create and bind a DatagramChannel to listen on. DatagramChannel udpserver = DatagramChannel.open(); udpserver.socket().bind(localport); // Specify non-blocking mode for both channels, since our // Selector object will be doing the blocking for us. tcpserver.configureBlocking(false); udpserver.configureBlocking(false); // The Selector object is what allows us to block while waiting // for activity on either of the two channels. Selector selector = Selector.open(); tcpserver.register(selector, SelectionKey.OP_ACCEPT); udpserver.register(selector, SelectionKey.OP_READ); System.out.println("Server Sterted on port: " + port + "!"); //Load Map Utils.LoadMap("mapa"); System.out.println("Server map ... LOADED!"); // Now loop forever, processing client connections while(true) { try { selector.select(); Set<SelectionKey> keys = selector.selectedKeys(); // Iterate through the Set of keys. for (Iterator<SelectionKey> i = keys.iterator(); i.hasNext();) { SelectionKey key = i.next(); i.remove(); Channel c = key.channel(); if (key.isAcceptable() && c == tcpserver) { new TCPThread(tcpserver.accept().socket()).start(); } else if (key.isReadable() && c == udpserver) { new UDPThread(udpserver.socket()).start(); } } } catch (Exception e) { e.printStackTrace(); } } } catch (Exception e) { e.printStackTrace(); System.err.println(e); System.exit(1); } } } The UDPThread code: public class UDPThread extends Thread { private DatagramSocket socket = null; public UDPThread(DatagramSocket socket) { super("UDPThread"); this.socket = socket; } @Override public void run() { byte[] buffer = new byte[2048]; try { DatagramPacket packet = new DatagramPacket(buffer, buffer.length); socket.receive(packet); String inputLine = new String(buffer); String outputLine = Utils.processCommand(inputLine.trim()); DatagramPacket reply = new DatagramPacket(outputLine.getBytes(), outputLine.getBytes().length, packet.getAddress(), packet.getPort()); socket.send(reply); } catch (IOException e) { e.printStackTrace(); } socket.close(); } } I receive: Exception in thread "UDPThread" java.nio.channels.IllegalBlockingModeException at sun.nio.ch.DatagramSocketAdaptor.receive(Unknown Source) at server.UDPThread.run(UDPThread.java:25) 10x

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Where are the function address literals in c++?

- by academicRobot

First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). <UPDATE> After some reading with help from answer by Chris Dodd, what I'm looking for is literal function addresses as template parameters. Chris' answer indicates how to do this for standard functions, but how can the addresses of member functions be used as template parameters? Since the standard prohibits non-static member function addresses as template parameters (c++03 14.3.2.3), I suspect the work around is quite complicated. Any ideas for a workaround? Below the original form of the question is left as is for context. </UPDATE> The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one. Edit The intent of this question is not to implement delegates, rather to identify a pattern that will embed a conventional function call, (in immediate mode) directly into third party code, possibly a template.

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How can I determine if an image has loaded, using Javascript/jQuery?

- by Kip

I'm writing some Javascript to resize the large image to fit into the user's browser window. (I don't control the size of the source images unfortunately.) So something like this would be in the HTML: <img id="photo" src="a_really_big_file.jpg" alt="this is some alt text" title="this is some title text" /> Is there a way for me to determine if the src image in an img tag has been downloaded? I need this because I'm running into a problem if $(document).ready() is executed before the browser has loaded the image. $("#photo").width() and $("#photo").height() will return the size of the placeholder (the alt text). In my case this is something like 134 x 20. Right now I'm just checking if the photo's height is less than 150, and assuming that if so it is just alt text. But this is quite a hack, and it would break if a photo is less than 150 pixels tall (not likely in my particular case), or if the alt text is more than 150 pixels tall (could possibly happen on a small browser window). Edit: For anyone wanting to see the code: $(function() { var REAL_WIDTH = $("#photo").width(); var REAL_HEIGHT = $("#photo").height(); $(window).resize(adjust_photo_size); adjust_photo_size(); function adjust_photo_size() { if(REAL_HEIGHT < 150) { REAL_WIDTH = $("#photo").width(); REAL_HEIGHT = $("#photo").height(); if(REAL_HEIGHT < 150) { //image not loaded.. try again in a quarter-second setTimeout(adjust_photo_size, 250); return; } } var new_width = . . . ; var new_height = . . . ; $("#photo").width(Math.round(new_width)); $("#photo").height(Math.round(new_height)); } }); Update: Thanks for the suggestions. There is a risk of the event not being fired if I set a callback for the $("#photo").load event, so I have defined an onLoad event directly on the image tag. For the record, here is the code I ended up going with: <img id="photo" onload="photoLoaded();" src="a_really_big_file.jpg" alt="this is some alt text" title="this is some title text" /> Then in Javascript: //This must be outside $() because it may get called first var isPhotoLoaded = false; function photoLoaded() { isPhotoLoaded = true; } $(function() { //Hides scrollbars, so we can resize properly. Set with JS instead of // CSS so that page doesn't break with JS disabled. $("body").css("overflow", "hidden"); var REAL_WIDTH = -1; var REAL_HEIGHT = -1; $(window).resize(adjust_photo_size); adjust_photo_size(); function adjust_photo_size() { if(!isPhotoLoaded) { //image not loaded.. try again in a quarter-second setTimeout(adjust_photo_size, 250); return; } else if(REAL_WIDTH < 0) { //first time in this function since photo loaded REAL_WIDTH = $("#photo").width(); REAL_HEIGHT = $("#photo").height(); } var new_width = . . . ; var new_height = . . . ; $("#photo").width(Math.round(new_width)); $("#photo").height(Math.round(new_height)); } });

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System.Threading.Timer Doesn't Trigger my TimerCallBack Delegate

- by Tom Kong

Hi, I am writing my first Windows Service using C# and I am having some trouble with my Timer class. When the service is started, it runs as expected but the code will not execute again (I want it to run every minute) Please take a quick look at the attached source and let me know if you see any obvious mistakes! TIA using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Diagnostics; using System.Linq; using System.ServiceProcess; using System.Text; using System.Threading; using System.IO; namespace CXO001 { public partial class Service1 : ServiceBase { public Service1() { InitializeComponent(); } /* * Aim: To calculate and update the Occupancy values for the different Sites * * Method: Retrieve data every minute, updating a public value which can be polled */ protected override void OnStart(string[] args) { Daemon(); } public void Daemon() { TimerCallback tcb = new TimerCallback(On_Tick); TimeSpan duetime = new TimeSpan(0, 0, 1); TimeSpan interval = new TimeSpan(0, 1, 0); Timer querytimer = new Timer(tcb, null, duetime, interval); } protected override void OnStop() { } static int[] floorplanids = new int[] { 115, 114, 107, 108 }; public static List<Record> Records = new List<Record>(); static bool firstrun = true; public static void On_Tick(object timercallback) { //Update occupancy data for the last minute //Save a copy of the public values to HDD with a timestamp string starttime; if (Records.Count > 0) { starttime = Records.Last().TS; firstrun = false; } else { starttime = DateTime.Today.AddHours(7).ToString(); firstrun = true; } DateTime endtime = DateTime.Now; GetData(starttime, endtime); } public static void GetData(string starttime, DateTime endtime) { string connstr = "Data Source = 192.168.1.123; Initial Catalog = Brickstream_OPS; User Id = Brickstream; Password = bstas;"; DataSet resultds = new DataSet(); //Get the occupancy for each Zone foreach (int zone in floorplanids) { SQL s = new SQL(); string querystr = "SELECT SUM(DIRECTIONAL_METRIC.NUM_TO_ENTER - DIRECTIONAL_METRIC.NUM_TO_EXIT) AS 'Occupancy' FROM REPORT_OBJECT INNER JOIN REPORT_OBJ_METRIC ON REPORT_OBJECT.REPORT_OBJ_ID = REPORT_OBJ_METRIC.REPORT_OBJECT_ID INNER JOIN DIRECTIONAL_METRIC ON REPORT_OBJ_METRIC.REP_OBJ_METRIC_ID = DIRECTIONAL_METRIC.REP_OBJ_METRIC_ID WHERE (REPORT_OBJ_METRIC.M_START_TIME BETWEEN '" + starttime + "' AND '" + endtime.ToString() + "') AND (REPORT_OBJECT.FLOORPLAN_ID = '" + zone + "');"; resultds = s.Go(querystr, connstr, zone.ToString(), resultds); } List<Record> result = new List<Record>(); int c = 0; foreach (DataTable dt in resultds.Tables) { Record r = new Record(); r.TS = DateTime.Now.ToString(); r.Zone = dt.TableName; if (!firstrun) { r.Occupancy = (dt.Rows[0].Field<int>("Occupancy")) + (Records[c].Occupancy); } else { r.Occupancy = dt.Rows[0].Field<int>("Occupancy"); } result.Add(r); c++; } Records = result; MrWriter(); } public static void MrWriter() { StringBuilder output = new StringBuilder("Time,Zone,Occupancy\n"); foreach (Record r in Records) { output.Append(r.TS); output.Append(","); output.Append(r.Zone); output.Append(","); output.Append(r.Occupancy.ToString()); output.Append("\n"); } output.Append(firstrun.ToString()); output.Append(DateTime.Now.ToFileTime()); string filePath = @"C:\temp\CXO.csv"; File.WriteAllText(filePath, output.ToString()); } } }

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Element.appendChild() hosed in IE .. workaround? (related to innerText vs textContent)

- by Rowe Morehouse

I've heard that using el.innerText||el.textContent can yield unreliable cross-browswer results, so I'm walking the DOM tree to collect text nodes recursively, and write them into tags in the HTML body. What this script does is read hash substring valus from the window.location and write them into the HTML. This script is working for me in Chrome & Firefox, but choking in IE. I call the page with an URL syntax like this: http://example.com/pagename.html#dyntext=FOO&dynterm=BAR&dynimage=FRED UPDATE UPDATE UPDATE Solution: I moved the scripts to before </body> (where they should have been) then removed console.log(sPageURL); and now it's working in Chrome, Firefox, IE8 and IE9. This my workaround for the innerText vs textContent crossbrowser issue when you are just placing text rather than getting text. In this case, getting hash substring values from the window.location and writing them into the page. <html> <body> <span id="dyntext-span" style="font-weight: bold;"></span><br /> <span id="dynterm-span" style="font-style: italic;"></span><br /> <span id="dynimage-span" style="text-decoration: underline;"></span><br /> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8/jquery.min.js"></script> <script> $(document).ready(function() { var tags = ["dyntext", "dynterm", "dynimage"]; for (var i = 0; i < tags.length; ++i) { var param = GetURLParameter(tags[i]); if (param) { var dyntext = GetURLParameter('dyntext'); var dynterm = GetURLParameter('dynterm'); var dynimage = GetURLParameter('dynimage'); } } var elem = document.getElementById("dyntext-span"); var text = document.createTextNode(dyntext); elem.appendChild(text); var elem = document.getElementById("dynterm-span"); var text = document.createTextNode(dynterm); elem.appendChild(text); var elem = document.getElementById("dynimage-span"); var text = document.createTextNode(dynimage); elem.appendChild(text); }); function GetURLParameter(sParam) { var sPageURL = window.location.hash.substring(1); var sURLVariables = sPageURL.split('&'); for (var i = 0; i < sURLVariables.length; i++) { var sParameterName = sURLVariables[i].split('='); if (sParameterName[0] == sParam) { return sParameterName[1]; } } } </script> </body> </html> FINAL UPDATE If your hash substring values require spaces (like a linguistic phrase with three words, for example) then separate the words with the + character in your URI, and replace the unicode \u002B character with a space when you create each text node, like this: var elem = document.getElementById("dyntext-span"); var text = document.createTextNode(dyntext.replace(/\u002B/g, " ")); elem.appendChild(text); var elem = document.getElementById("dynterm-span"); var text = document.createTextNode(dynterm.replace(/\u002B/g, " ")); elem.appendChild(text); var elem = document.getElementById("dynimage-span"); var text = document.createTextNode(dynimage.replace(/\u002B/g, " ")); elem.appendChild(text); Now form your URI like this: http://example.com/pagename.html#dyntext=FOO+MAN+CHU&dynterm=BAR+HOPPING&dynimage=FRED+IS+DEAD

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