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  • HTTP Compression problems on IIS7

    - by Jonathan Wood
    I've spent quite a bit of time on this but seem to be going nowhere. I have a large page that I really want to speed up. The obvious place to start seems to be HTTP compression, but I just can't seem to get it to work for me. After considerable searching, I've tried several variations of the code below. It kind of works, but after refreshing the browser, the results seem to fall apart. They were turning to garbage when the page used caching. If I turn off caching, then the page seems right but I lose my CSS formatting (stored in a separate file) and get an error that an included JS file contains invalid characters. Most of the resources I've found on the Web were either very old or focused on accessing IIS directly. My page is running on a shared hosting account and I do not have direct access to IIS7, which it's running on. protected void Application_BeginRequest(object sender, EventArgs e) { // Implement HTTP compression if (Request["HTTP_X_MICROSOFTAJAX"] == null) // Avoid compressing AJAX calls { // Retrieve accepted encodings string encodings = Request.Headers.Get("Accept-Encoding"); if (encodings != null) { // Verify support for or gzip (deflate takes preference) encodings = encodings.ToLower(); if (encodings.Contains("gzip") || encodings == "*") { Response.Filter = new GZipStream(Response.Filter, CompressionMode.Compress); Response.AppendHeader("Content-Encoding", "gzip"); Response.Cache.VaryByHeaders["Accept-encoding"] = true; } else if (encodings.Contains("deflate")) { Response.Filter = new DeflateStream(Response.Filter, CompressionMode.Compress); Response.AppendHeader("Content-Encoding", "deflate"); Response.Cache.VaryByHeaders["Accept-encoding"] = true; } } } } Is anyone having better success with this?

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  • Python: Does one of these examples waste more memory?

    - by orokusaki
    In a Django view function which uses manual transaction committing, I have: context = RequestContext(request, data) transaction.commit() return render_to_response('basic.html', data, context) # Returns a Django ``HttpResponse`` object which is similar to a dictionary. I think it is a better idea to do this: context = RequestContext(request, data) response = render_to_response('basic.html', data, context) transaction.commit() return response If the page isn't rendered correctly in the second version, the transaction is rolled back. This seems like the logical way of doing it albeit there won't likely be many exceptions at that point in the function when the application is in production. But... I fear that this might cost more and this will be replete through a number of functions since the application is heavy with custom transaction handling, so now is the time to figure out. If the HttpResponse instance is in memory already (at the point of render_to_response()), then what does another reference cost? When the function ends, doesn't the reference (response variable) go away so that when Django is done converting the HttpResponse into a string for output Python can immediately garbage collect it? Is there any reason I would want to use the first version (other than "It's 1 less line of code.")?

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  • unhandled exception Handler in .Net 3.5 SP1

    - by Ruony
    Hi. I'm converting my own web browser use WPF from Windows XP to Windows 7. when I test on Windows XP, It has no error and exceptions. But I convert and test on Windows 7 with Multi-touch Library, My Browser occurred unhandled exception. Source: PresentationCore Message: An unspecified error occurred on the render thread. StackTrace: at System.Windows.Media.MediaContext.**NotifyPartitionIsZombie**(Int32 failureCode) at System.Windows.Media.MediaContext.NotifyChannelMessage() at System.Windows.Interop.HwndTarget.HandleMessage(Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Interop.HwndSource.HwndTargetFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) InnerException: null I want to know where the bug occurred. That Trace Message are garbage information for me. I already googling to know that message, but i never found any information. How do I get exactly function where the bug occurred? please tell me something.

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  • Process xml-like log file queue

    - by Zsolt Botykai
    Hi all, first of all: I'm not a programmer, never was, although had learn a lot during my professional carreer as a support consultant. Now my task is to process - and create some statistics about a constantly written and rapidly growing XML like log file. It's not valid XML, because it does not have a proper <root> element, e.g. the log looks like this: <log itemdate="somedate"> <field id="0" /> ... </log> <log itemdate="somedate+1"> <field id="0" /> ... </log> <log itemdate="somedate+n"> <field id="0" /> ... </log> E.g. I have to count all the items with field id=0. But most of the solutions I had found (e.g. using XPath) reports an error about the garbage after the first closing </log>. Most probably I can use python (2.6, although I can compile 3.x as well), or some really old perl version (5.6.x), and recently compiled xmlstarlet which really looks promising - I was able to create the statistics for a certain period after copying the file, and pre- & appending the opening and closing root element. But this is a huge file and copying takes time as well. Isn't there a better solution? Thanks in advance!

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  • libarchive reads too many chars when extracting a file

    - by ojreadmore
    I've written a C program to extract files from a tar archive using libarchive. I'd like to extract a file from this archive and print it to standard output. But I get extra characters. It's garbage, but it's from another file (possibly adjacent to it in the archive.) I expect output to end at </html>. Here is the code that reads this tar file. libarchive 2.8.3 compiled on mac os X 10.6.3. gcc 4.2 x86_64 ls -l vendar-definition.html gives me 1921 for the file size. And so shows tar tfv 0000.tar | grep vendar-definition.html. So reports the C output that states the file size. To me this seems correct. Two possibilities I can see for why my output is not as expected: 1. I've made a beginner's mistake or 2. multibyte characters in the archive files has something to do with it.

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  • Copying to binary file row of a matrix

    - by Flethuseo
    Hi everyone I want to write each row of a matrix to a binary file. I try writing it like this: vector< vector<uint32_t> > matrix; ... for(size_t i = 0; i < matrix.size(); ++i) ofile->write( reinterpret_cast<char*>(&matrix[i]), sizeof(uint32_t*sizeof(matrix[i])) ); { for(size_t j = 0; j < numcols; ++j) { std::cout << left << setw(10) << matrix[i][j]; } cout << endl; } but it doesn't work, I get garbage numbers. Any help appreciated, Ted.

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  • Large ListView containing images in Android

    - by Marco W.
    For various Android applications, I need large ListViews, i.e. such views with 100-300 entries. All entries must be loaded in bulk when the application is started, as some sorting and processing is necessary and the application cannot know which items to display first, otherwise. So far, I've been loading the images for all items in bulk as well, which are then saved in an ArrayList<CustomType> together with the rest of the data for each entry. But of course, this is not a good practice, as you're very likely to have an OutOfMemoryException then: The references to all images in the ArrayList prevent the garbage collector from working. So the best solution is, obviously, to load only the text data in bulk whereas the images are then loaded as needed, right? The Google Play application does this, for example: You can see that images are loaded as you scroll to them, i.e. they are probably loaded in the adapter's getView() method. But with Google Play, this is a different problem, anyway, as the images must be loaded from the Internet, which is not the case for me. My problem is not that loading the images takes too long, but storing them requires too much memory. So what should I do with the images? Load in getView(), when they are really needed? Would make scrolling sluggish. So calling an AsyncTask then? Or just a normal Thread? Parametrize it? I could save the images that are already loaded into a HashMap<String,Bitmap>, so that they don't need to be loaded again in getView(). But if this is done, you have the memory problem again: The HashMap stores references to all images, so in the end, you could have the OutOfMemoryException again. I know that there are already lots of questions here that discuss "Lazy loading" of images. But they mainly cover the problem of slow loading, not too much memory consumption.

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  • error in arabic script in mysql

    - by fusion
    i inserted data in mysql database which includes arabic script. while the output displays arabic correctly, the data in mysql looks like garbage. something like this: '&#1589;&#1614;&#1608;&#1605;&#1615; &#1579;&#1614;&#1604;&#1575;&#1579;&#1614;&#1577;&#1616; &#1571;&#1610;&#1617;&#1575;&#1605;&#1613; &#1605;&#1616;&#1606; &#1603;&#1615;&#1604;&#1617;&#1616; &#1588;&#1614;&#1607;&#1585;&#1613; &#1600; &#1571;&#1585;&#1576;&#1614;&#1593;&#1575;&#1569;&#1615; &#1576;&#1614;&#1610;&#1606;&#1614; &#1582;&#1614; should i be worried about this? if yes, how do i make it appear in proper arabic script in mysql? thanks.

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  • "end()" iterator for back inserters?

    - by Thanatos
    For iterators such as those returned from std::back_inserter(), is there something that can be used as an "end" iterator? This seems a little nonsensical at first, but I have an API which is: template<typename InputIterator, typename OutputIterator> void foo( InputIterator input_begin, InputIterator input_end, OutputIterator output_begin, OutputIterator output_end ); foo performs some operation on the input sequence, generating an output sequence. (Who's length is known to foo but may or may not be equal to the input sequence's length.) The taking of the output_end parameter is the odd part: std::copy doesn't do this, for example, and assumes you're not going to pass it garbage. foo does it to provide range checking: if you pass a range too small, it throws an exception, in the name of defensive programming. (Instead of potentially overwriting random bits in memory.) Now, say I want to pass foo a back inserter, specifically one from a std::vector which has no limit outside of memory constraints. I still need a "end" iterator - in this case, something that will never compare equal. (Or, if I had a std::vector but with a restriction on length, perhaps it might sometimes compare equal?) How do I go about doing this? I do have the ability to change foo's API - is it better to not check the range, and instead provide an alternate means to get the required output range? (Which would be needed anyways for raw arrays, but not required for back inserters into a vector.) This would seem less robust, but I'm struggling to make the "robust" (above) work.

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  • Flash Player: Any remedy for the stale video image data problem (in a reused NetStream object)?

    - by amn
    Has anyone experienced stale stills of a previous playback for a reused NetStream object? If so, what are the workarounds for this, except re-creating the object (which eats performance and time)? It is hard to reuse NetStream objects because of a (in my opinion) fundamental issue with NetStream objects - when you 'close' a playing stream and at a later point issue a 'play' call on it again with a different name, the stream appears to still contain a stale image lingering from previous playback, and this is of course displayed in the Video object for a moment - the moment I assume it takes for new stream data to become available from server. Because of this behavior, to improve my users' visual experience, I simply discard a NetStream object after a playback session, and assign a new NetStream object to the same variable, set it up, and play something else. It appears to work - no stale image - but what bugs me is that it's a work around and costs performance (construction and setting up the object again - event listeners and 'client' delegates and more memory usage - NetStream objects are not garbage collected immediately, it takes some time). It would be really nice to REALLY be able to reuse a stream. I am thinking of something akin to Video.clear method, but for the NetStream class. Am I missing something?

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  • Better language or checking tool?

    - by rwallace
    This is primarily aimed at programmers who use unmanaged languages like C and C++ in preference to managed languages, forgoing some forms of error checking to obtain benefits like the ability to work in extremely resource constrained systems or the last increment of performance, though I would also be interested in answers from those who use managed languages. Which of the following would be of most value? A language that would optionally compile to CLR byte code or to machine code via C, and would provide things like optional array bounds checking, more support for memory management in environments where you can't use garbage collection, and faster compile times than typical C++ projects. (Think e.g. Ada or Eiffel with Python syntax.) A tool that would take existing C code and perform static analysis to look for things like potential null pointer dereferences and array overflows. (Think e.g. an open source equivalent to Coverity.) Something else I haven't thought of. Or put another way, when you're using C family languages, is the top of your wish list more expressiveness, better error checking or something else? The reason I'm asking is that I have a design and prototype parser for #1, and an outline design for #2, and I'm wondering which would be the better use of resources to work on after my current project is up and running; but I think the answers may be useful for other tools programmers also. (As usual with questions of this nature, if the answer you would give is already there, please upvote it.)

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  • Need advanced mod_rewrite assistance

    - by user1647719
    This is driving me bananas. I have tried multiple fixes, and have even found a generator (generateit.net/mod-rewrite/) to create my .htaccess files, but I cannot get this to work. The .htaccess file is being read - if I put garbage characters in, I get a 500 server error. Also, mod rewrite was working in a simpler format, but the client wants even more SEO, so here I am. My intention: Take the url of brinkofdesign.com/portfolio/123/456/some_seo_text.html and send it to brinkofdesign.com/brink_portfolio.php?catid=123&locationid=456. The full contents of my .htaccess file are: Options +FollowSymlinks RewriteEngine on RewriteBase / RewriteRule ^portfolio([^/]*)/([^/]*)/([^/]*)\.html$ /portfolio_brink.php?catid=$1&locationid=$2&page=$3 [NC,L] RewriteRule ^(.*)blog(.+)([0-9+])(.+).html$ blog.php?blogid=$3 [NC,L] RewriteRule ^blog.xml$ blogfeed.php The blog and blogfeed parts work fine. If it matters, I do have an actual portfolio.php page - could this be breaking it? There is no actual /portfolio/ folder - this is just part of the SEO nme. Also, the host is 1and1.com. Real life tests: brinkofdesign.com/portfolio/1/1/birmingham_al_corporate_branding.html loads my actual portfolio.php page - which is supposed to be a landing page for the portfolio, as opposed to the brink_portfolio.php page, which is my detail record page. No variables are passed (echoing out the contents of the $_GET array gives an empty array). Typing in an non SEO link like brinkofdesign.com/brink_portfolio.php?catid=1&locationid=1 does work correctly. Gurus, please help me!

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  • [IE6] Cannot upload non-existent file

    - by geff_chang
    I am asking the same question as this: http://stackoverflow.com/questions/691323/trying-to-upload-a-non-existent-file-in-internet-explorer-form-is-not-submitted I'm not sure if the topic starter found a solution, since he did not post the answer. So, I'd like to ask you guys this question again. I have type=input in my form, and a submit button. If I type garbage input into the textbox (like the text "abc") in the file control's textbox, and click the submit button, the form is not submitted to the server. AND, no feedback is given to the user. Instead of this "Is-the-submit-button-broken?" behavior, is there a way I could notify the user that the file does not exist? (I am aware this is not possible, except with ActiveX, but I don't want to go into that) My client wants to hide the textbox of the file control, but I'm not sure if this is a good design. What do you guys suggest? (If it makes any difference, I am also using this jquery plugin: http://www.fyneworks.com/jquery/multiple-file-upload/)

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  • Is app stability unusually hard with Java?

    - by wrp
    Java's extensive libraries and tool support are appealing, but I've never tried developing with it because most Java applications I've used have been extremely buggy. This has me puzzled, because I hear that Java is the dominant platform for enterprise development. Maybe it's fine for server-side stuff but not desktop applications. I'm not talking about things like the long compile/startup times or the random latencies due to garbage collection. This is about things just going wrong. Some of the most common problems I see are: corrupted icons corrupted fonts, in menus usually and editing areas sometimes inaccurate framing of GUI elements dialogs sometimes popping up blank Maybe the problems are mostly with Swing. I've rarely used a Java application long enough to find deeper issues. I can think of a few possible explanations for what I've experienced: It's possible to write stable apps with Java, just harder. Java apps are always buggy and enterprise users just put up with it. Server-side apps are fine because just Swing is buggy. I'm living under a curse and need the services of a good witchdoctor.

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  • Python ctypes in_dll string assignment

    - by ackdesha
    I could use some help assigning to a global C variable in DLL using ctypes. The following is an example of what I'm trying: test.c contains the following #include <stdio.h> char name[60]; void test(void) { printf("Name is %s\n", name); } On windows (cygwin) I build a DLL (Test.dll) as follows: gcc -g -c -Wall test.c gcc -Wall -mrtd -mno-cygwin -shared -W1,--add-stdcall-alias -o Test.dll test.o When trying to modify the name variable and then calling the C test function using the ctypes interface I get the following... >>> from ctypes import * >>> dll = windll.Test >>> dll <WinDLL 'Test', handle ... at ...> >>> f = c_char_p.in_dll(dll, 'name') >>> f c_char_p(None) >>> f.value = 'foo' >>> f c_char_p('foo') >>> dll.test() Name is Name is 48+? 13 Why does the test function print garbage in this case?

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  • Ruby integer to string key

    - by Gene
    A system I'm building needs to convert non-negative Ruby integers into shortest-possible UTF-8 string values. The only requirement on the strings is that their lexicographic order be identical to the natural order on integers. What's the best Ruby way to do this? We can assume the integers are 32 bits and the sign bit is 0. This is successful: (i >> 24).chr + ((i >> 16) & 0xff).chr + ((i >> 8) & 0xff).chr + (i & 0xff).chr But it appears to be 1) garbage-intense and 2) ugly. I've also looked at pack solutions, but these don't seem portable due to byte order. FWIW, the application is Redis hash field names. Building keys may be a performance bottleneck, but probably not. This question is mostly about the "Ruby way".

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  • NDK app onDestroy cleanup - how to DetachCurrentThread

    - by Aristarhys
    So if we attach we must detach thread after after it finish, right? JNIEnv* get_jni_env() { JNIEnv* res; JAVA_VM->GetEnv((void**) &res, JNI_VERSION_1_6);//Using cached JavaVM JAVA_VM->AttachCurrentThread(&res, NULL); return res; } I call next native method from @Override protected void onDestroy() of my Activity class void free_jni_manager() { JNIEnv* env = get_jni_env(); ... //Here i delete global refs (jclass) //JAVA_VM->DetachCurrentThread(); } ERROR: detaching thread with interp frames (count=16) - main thread still running and we try to detach it. Even if we take any function that use JNIEnv (for example calling java methods), putting DetachCurrentThread will cause same error. DetachCurrentThread works flawlessly if used in pthread function static void* thread_func(void* arg) { get_jni_env(); // attach new thread //Do thread stuff JAVA_VM->DetachCurrentThread();//thread done detached it with ok return NULL; } Do we need detach main thread then we done with JNI, there do it? Or then activity will be destroyed, it will freed itself with JavaVM? Do we need do call DestroyJavaVM() (just doing crash if use onDestroy), how free cached JavaVM or garbage cleaner will handle this? P.S. What benefits of using AttachCurrentThreadAsDaemon()

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  • Singleton issue causing a buffer overrun

    - by Rudiger
    Hi everyone, Ive created a singleton to store 2 arrays: @interface Globals : NSObject { NSMutableArray *items; NSMutableArray *extras; } + (Globals *)sharedInstance; @property (nonatomic, assign) NSMutableArray *items; @property (nonatomic, assign) NSMutableArray *extras; @end @implementation Globals @synthesize items, extras; + (Globals *)sharedInstance { static Globals *myInstance = nil; @synchronized(self) { if(!myInstance) { myInstance = [[Globals alloc] init]; } } return myInstance; } -(void)dealloc { [items release]; [extras release]; [super dealloc]; } @end When I set the Arrays in the singleton from the App delegate and then output them to NSLog it displays what is expected. But when I call it from a view controller further into the App it displays the first entry fine, some of the second entry and then garbage which is i assume a buffer overrun, sometimes it also crashes. I set the singleton array in the appDelegate like so: Globals *sharedInstance = [Globals sharedInstance]; [sharedInstance setItems:items]; and retrieve it: [[[sharedInstance items] objectAtIndex:indexPath.row] objectForKey:@"name"]; cell.description.text = [[[sharedInstance items] objectAtIndex:indexPath.row] objectForKey:@"description"]; Name works fine in both cells if there is 2, description works in the first case, never in the second case. Is it because the arrays in my singleton aren't static? If so why is it outputting the first entry fine? Cheers for any help.

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  • How to optimalize my game calendar in C#?

    - by MartyIX
    Hi, I've implemented a simple calendar (message system) for my game which consists from: 1) List<Event> calendar; 2) public class Event { /// <summary> /// When to process the event /// </summary> public Int64 when; /// <summary> /// Which object should process the event /// </summary> public GameObject who; /// <summary> /// Type of event /// </summary> public EventType what; public int posX; public int posY; public int EventID; } 3) calendar.Add(new Event(...)) The problem with this code is that even thought the number of messages is not excessise per second. It allocates still new memory and GC will once need to take care of that. The garbage collection may lead to a slight lag in my game and therefore I'd like to optimalize my code. My considerations: To change Event class in a structure - but the structure is not entirely small and it takes some time to copy it wherever I need it. Reuse Event object somehow (add queue with used events and when new event is needed I'll just take from this queue). Does anybody has other idea how to solve the problem? Thanks for suggestions!

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  • Fastest reliable way for Clojure (Java) and Ruby apps to communicate

    - by jkndrkn
    Hi There, We have cloud-hosted (RackSpace cloud) Ruby and Java apps that will interact as follows: Ruby app sends a request to Java app. Request consists of map structure containing strings, integers, other maps, and lists (analogous to JSON). Java app analyzes data and sends reply to Ruby App. We are interested in evaluating both messaging formats (JSON, Buffer Protocols, Thrift, etc.) as well as message transmission channels/techniques (sockets, message queues, RPC, REST, SOAP, etc.) Our criteria: Short round-trip time. Low round-trip-time standard deviation. (We understand that garbage collection pauses and network usage spikes can affect this value). High availability. Scalability (we may want to have multiple instances of Ruby and Java app exchanging point-to-point messages in the future). Ease of debugging and profiling. Good documentation and community support. Bonus points for Clojure support. What combination of message format and transmission method would you recommend? Why? I've gathered here some materials we have already collected for review: Comparison of various java serialization options Comparison of Thrift and Protocol Buffers (old) Comparison of various data interchange formats Comparison of Thrift and Protocol Buffers Fallacies of Protocol Buffers RPC features Discussion of RPC in the context of AMQP (Message-Queueing) Comparison of RPC and message-passing in distributed systems (pdf) Criticism of RPC from perspective of message-passing fan Overview of Avro from Ruby programmer perspective

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  • Jquery UI dialog does not disappear

    - by iamrohitbanga
    I am using jquery-ui tabs and dialog functionality. Each tab has a button on the page which opens a dialog. This works for one of the tabs. However if I go the second tab, the button does not work there. When I come back to the first tab, the dialog does show up but the problem is I notice as I make switches back and forth to the first tab, it keeps on inserting new div's while the old div's have display:none set on them. I am doing this using JSP. This is how the reusable jsp looks like: <script> $(function() { var formData = null; $.ajax({ url : "addFormGenerator.html", success : function(data) { formData = data; $("#addFormDialog").html(data); $("#addFormDialog").dialog({ autoOpen : false, height : 300, width : 350, modal : true, buttons : { "Add" : function() { $(this).dialog("close"); }, Cancel : function() { $(this).dialog("close"); } }, close : function() { } }); } }); $("#addButton").button().click(function() { $("#addFormDialog").html(formData); $("#addFormDialog").dialog("open"); }); }); </script> <button id="addButton">Click here to Add New</button> <div id="addFormDialog" title="Add New"></div> This jsp fragment is included in other jsp pages as well. I was assuming as I switch between tabs the old button will be garbage collected. Can you help me understand the problem and fix it?

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  • transferring binary files between systems

    - by tim
    Hi guys I'm trying to transfer my files between 2 UNIX clusters, the data is pure numeric (vectors of double) in binary form. Unfortunately one of the systems is IBM ppc997 and the other is AMD Opteron, It seems the format of binary numbers in these systems are different. I have tried 3 ways till now: 1- Changed my files to ASCII format (i.e. saved a number at each line in a text file), sent them to the destination and changed them again to binary on the target system (they both are UNIX, no end of line character difference??!) 2- Sent pure binaries to the destination 3- used uuencode sent them to the destination and decoded them Unfortunately any of these methods does not work (my code in the destination system generates garbage, while it works on the first system, I'm 100% sure the code itself is portable). I don't know what else I can do? Do you have any idea? I'm not a professional, please don't use computer scientists terminology! And: my codes are in C, so by binary I mean a one to one mapping between memory and hard disk. Thanks

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  • Does ReleaseStringUTF do more than free memory?

    - by Bayou Bob
    Consider the following C code segments. Segment 1: char * getSomeString(JNIEnv *env, jstring jstr) { char * retString; retString = (*env)->GetStringUTFChars(env, jstr, NULL); return retString; } void useSomeString(JNIEnv *env, jobject jobj, char *mName) { jclass cl = (*env)->GetObjectClass(env, jobj); jmethodId mId = (*env)->GetMethodID(env, cl, mName, "()Ljava/lang/String;"); jstring jstr = (*env)->CallObjectMethod(env, obj, id, NULL); char * myString = getSomeString(env, jstr); /* ... use myString without modifing it */ free(myString); } Because myString is freed in useSomeString, I do not think I am creating a memory leak; however, I am not sure. The JNI spec specifically requires the use of ReleaseStringUTFChars. Since I am getting a C style 'char *' pointer from GetStringUTFChars, I believe the memory reference exists on the C stack and not in the JAVA heap so it is not in danger of being Garbage Collected; however, I am not sure. I know that changing getSomeString as follows would be safer (and probably preferable). Segment 2: char * getSomeString(JNIEnv *env, jstring jstr) { char * retString; char * intermedString; intermedString = (*env)->GetStringUTFChars(env, jstr, NULL); retString = strdup(intermedString); (*env)->ReleaseStringUTFChars(env, jstr, intermedString); return retString; } Because of our 'process' I need to build an argument on why getSomeString in Segment 2 is preferable to Segment 1. Is anyone aware of any documentation or references which detail the behavior of GetStringUTFChars and ReleaseStringUTFChars in relation to where memory is allocated or what (if any) additional bookkeeping is done (i.e. local Reference Pointer to the Java Heap being created, etc). What are the specific consequences of ignoring that bookkeeping. Thanks in advance.

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  • Pointers into elements in a container

    - by Pillsy
    Say I have an object: struct Foo { int bar_; Foo(int bar) bar_(bar) {} }; and I have an STL container that contains Foos, perhaps a vector, and I take // Elsewhere... vector<Foo> vec; vec.push_back(Foo(4)); int *p = &(vec[0].bar_) This is a terrible idea, right? The reason is that vector is going to be storing its elements in a dynamically allocated array somewhere, and eventually, if you add enough elements, it will have to allocate another array, copy over all the elements of the original array, and delete the old array. After that happens, p points to garbage. This is why many operations on a vector will invalidate iterators. It seems like it would be reasonable to assume that an operation that would invalidate iterators from a container will also invalidate pointers to data members of container elements, and that if an operation doesn't invalidate iterators, those pointers will still be safe. However, many reasonable assumptions are false. Is this one of them?

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  • Can a member struct be zero-init from the constructor initializer list without calling memset?

    - by selbie
    Let's say I have the following structure declaration (simple struct with no constructor). struct Foo { int x; int y; int z; char szData[DATA_SIZE]; }; Now let's say this struct is a member of a C++ class as follows: class CFoobar { Foo _foo; public: CFoobar(); }; If I declare CFoobar's constructor as follows: CFoobar::CFoobar() { printf("_foo = {%d, %d, %d}\n", _foo.x, _foo.y,_foo.z); for (int x = 0; x < 100; x++) printf("%d\n", _foo.szData[x]); } As you would expect, when CFoobar's constructor runs, garbage data gets printed out Obviously, the easy fix is to memset or ZeroMemory &_foo. It's what I've always done... However, I did notice that if add _foo to the constructor's initialization list with no parameters as follows: CFoobar::CFoobar() : _foo() { That this appears to zero-out the member variables of _foo. At least that was the case with g++ on linux. Now here's my question: Is this standard C++, or is this compiler specific behavior? If it's standard behavior, can someone quote me a reference from an official source? Any "gotchas" in regards to implicit zero-init behavior with more complicated structs and classes?

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