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  • Qt/MFC Migration Framework tool: properly exiting DLL?

    - by User
    I'm using the Qt/MFC Migration Framework tool following this example: http://doc.qt.nokia.com/solutions/4/qtwinmigrate/winmigrate-qt-dll-example.html The dll I build is loaded by a 3rd party MFC-based application. The 3rd party app basically calls one of my exported DLL functions to startup my plugin and another function to shutdown my application. Currently I'm doing nothing in my shutdown function. When I load my DLL in the 3rd party app the startup function is called and my DLL starts successfully and I can see my message box. However if I shutdown my plugin and then try to start it again I get the following error: Debug Error! Program: <my 3rd party app> Module: 4.7.1 File: global\qglobal.cpp Line: 2262 ASSERT failure in QWidget: "Widgets must be created in the GUI thread.", file kernel\qwidget.cpp line 1233 (Press Retry to debug the application) Abort Retry Ignore This makes me think I'm not doing something to properly shutdown my plugin. What do I need to do to shut it down properly? UPDATE: http://doc.qt.nokia.com/solutions/4/qtwinmigrate/winmigrate-walkthrough.html says: The DLL also has to make sure that it can be loaded together with other Qt based DLLs in the same process (in which case a QApplication object will probably exist already), and that the DLL that creates the QApplication object remains loaded in memory to avoid other DLLs using memory that is no longer available to the process. So I wonder if there is some problem where I need to somehow keep the original DLL loaded no matter what?

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  • A little confusion about AJAX and inserting into DOM..

    - by Gnee
    I have this working great, but I'd like a deeper understanding of what is actually going on behind the scenes. I am using Jquery's Ajax method to pull 5 blog posts (returning only the title and first photo). A PHP script grabs the blog posts' title and first photo and sticks it in an array and sends it back to my browser as JSON. Upon receiving the JSON object, Jquery grabs the first member of the JSON object and displays it's title and photo. In a gallery I made, using buttons – the user can iterate the 1-5 posts. So the actual AJAX call happens right away, and only once. I am basically using this kind of setup: $('my_div').html(json_obj[i]) and each click does a i++. So jquery is plucking these blog posts from my computers memory, my web browsers cache, or some kind of cache in the Javascript engine? One of the things it's returning is a pretty gnarly animated gif. I just wonder if it constantly running in the background (but not visible), stealing processing cycles...etc. Or Javascript just inserting (say a flash movie) into the DOM, but before hand does nothing but take up a little memory (no processing). Anyway, I'm just curious. If someone is a guru on this, I'd love to hear your take. THanks!!

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  • How to Avoid PHP Object Nesting/Creation Limit?

    - by Will Shaver
    I've got a handmade ORM in PHP that seems to be bumping up against an object limit and causing php to crash. Here's a simple script that will cause crashes: <? class Bob { protected $parent; public function Bob($parent) { $this->parent = $parent; } public function __toString() { if($this->parent) return (string) "x " . $this->parent; return "top"; } } $bobs = array(); for($i = 1; $i < 40000; $i++) { $bobs[] = new Bob($bobs[$1 -1]); } ?> Even running this from the command line will cause issues. Some boxes take more than 40,000 objects. I've tried it on Linux/Appache (fail) but my app runs on IIS/FastCGI. On FastCGI this causes the famous "The FastCGI process exited unexpectedly" error. Obviously 20k objects is a bit high, but it crashes with far fewer objects if they have data and nested complexity. Fast CGI isn't the issue - I've tried running it from the command line. I've tried setting the memory to something really high - 6,000MB and to something really low - 24MB. If I set it low enough I'll get the "allocated memory size xxx bytes exhausted" error. I'm thinking that it has to do with the number of functions that are called - some kind of nesting prevention. I didn't think that my ORM's nesting was that complicated but perhaps it is. I've got some pretty clear cases where if I load just ONE more object it dies, but loads in under 3 seconds if it works.

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  • Javascript: Whitespace Characters being Removed in Chrome (but not Firefox)

    - by Matrym
    Why would the below eliminate the whitespace around matched keyword text when replacing it with an anchor link? Note, this error only occurs in Chrome, and not firefox. For complete context, the file is located at: http://seox.org/lbp/lb-core.js To view the code in action (no errors found yet), the demo page is at http://seox.org/test.html. Copy/Pasting the first paragraph into a rich text editor (ie: dreamweaver, or gmail with rich text editor turned on) will reveal the problem, with words bunched together. Pasting it into a plain text editor will not. // Find page text (not in links) -> doxdesk.com function findPlainTextExceptInLinks(element, substring, callback) { for (var childi= element.childNodes.length; childi-->0;) { var child= element.childNodes[childi]; if (child.nodeType===1) { if (child.tagName.toLowerCase()!=='a') findPlainTextExceptInLinks(child, substring, callback); } else if (child.nodeType===3) { var index= child.data.length; while (true) { index= child.data.lastIndexOf(substring, index); if (index===-1 || limit.indexOf(substring.toLowerCase()) !== -1) break; // don't match an alphanumeric char var dontMatch =/\w/; if(child.nodeValue.charAt(index - 1).match(dontMatch) || child.nodeValue.charAt(index+keyword.length).match(dontMatch)) break; // alert(child.nodeValue.charAt(index+keyword.length + 1)); callback.call(window, child, index) } } } } // Linkup function, call with various type cases (below) function linkup(node, index) { node.splitText(index+keyword.length); var a= document.createElement('a'); a.href= linkUrl; a.appendChild(node.splitText(index)); node.parentNode.insertBefore(a, node.nextSibling); limit.push(keyword.toLowerCase()); // Add the keyword to memory urlMemory.push(linkUrl); // Add the url to memory } // lower case (already applied) findPlainTextExceptInLinks(lbp.vrs.holder, keyword, linkup); Thanks in advance for your help. I'm nearly ready to launch the script, and will gladly comment in kudos to you for your assistance.

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  • How to output KML by GAE

    - by Niklas R
    Hi I use KML for a google map where entities have a geopt.db coordinate and soft memory limit was exceeded with 213.465 MB after servicing 1 requests total. The log says /list.kml 200 13130ms 10211cpu_ms 4238api_cpu_ms The file list.kml which outputs about 455,7 KB is a template as follows <?xml version="1.0" encoding="UTF-8"?><kml xmlns="http:// www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http:// www.w3.org/2005/Atom"> <Document>{% for a in list %} <Placemark> <name> </name> <description> <![CDATA[<a href="http://{{host}}/{{a.key.id}}"> {{ a.title }} </a> <br/>{{a.text}}]]> </description> <Style> <IconStyle> <Icon> <href> http://www.google.com/intl/en_us/mapfiles/ms/icons/green-dot.png </href> </Icon> </IconStyle> </Style> <Point> <coordinates> {{a.geopt.lon|floatformat:2}},{{a.geopt.lat|floatformat:2}} </coordinates> </Point> </Placemark> {% endfor %} </Document> </kml> Is there a memory leak in the template or the python that passes the list variable? Can I improve using other template engine or other framework than default? Is kmz compression a good idea in this case? Thanks in advance for any suggestion where or how to change the code.

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  • Orphan IBM JVM process

    - by Nicholas Key
    Hi people, I have this issue about orphan IBM JVM process being created in the process tree: For example: C:\Program Files\IBM\WebSphere\AppServer\bin>wsadmin -lang jython -f "C:\Hello.py" Hello.py has the simple implementation: import time i = 0 while (1): i = i + 1 print "Hello World " + str(i) time.sleep(3.0) My machine has such JVM information: C:\Program Files\WebSphere\java\bin>java -verbose:sizes -version -Xmca32K RAM class segment increment -Xmco128K ROM class segment increment -Xmns0K initial new space size -Xmnx0K maximum new space size -Xms4M initial memory size -Xmos4M initial old space size -Xmox1624995K maximum old space size -Xmx1624995K memory maximum -Xmr16K remembered set size -Xlp4K large page size available large page sizes: 4K 4M -Xmso256K operating system thread stack size -Xiss2K java thread stack initial size -Xssi16K java thread stack increment -Xss256K java thread stack maximum size java version "1.6.0" Java(TM) SE Runtime Environment (build pwi3260sr6ifix-20091015_01(SR6+152211+155930+156106)) IBM J9 VM (build 2.4, JRE 1.6.0 IBM J9 2.4 Windows Server 2003 x86-32 jvmwi3260sr6-20091001_43491 (JIT enabled, AOT enabled) J9VM - 20091001_043491 JIT - r9_20090902_1330ifx1 GC - 20090817_AA) JCL - 20091006_01 While the program is running, I tried to kill it and subsequently I found an orphan IBM JVM process in the process tree. Is there a way to fix this issue? Why is there an orphan process in the first place? Is there something wrong with my code? I really don't believe that my simplistic code is wrongly implemented. Any suggestions?

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  • What is SSIS order of data transformation component method calls

    - by Ron Ruble
    I am working on a custom data transformation component. I'm using NUnit and NMock2 to test as I code. Testing and getting the custom UI and other features right is a huge pain, in part because I can't find any documentation about the order in which SSIS invokes methods on the component at design time as well as runtime. I can correct the issues readily enough, but it's tedious and time consuming to unregister the old version, register the new version, fire up the test ssis package, try to display the UI, get an obscure error message, backtrace it, modify the component and continue. One of the big issues involves the UI component needing access to the componentmetadata and buffermanager properties of the component at design time, and what I need to provide for to support properties that won't be initialized until after the user enters them in the UI. I can work through it; but if someone knows of some docs or tips that would speed me up, I'd greatly appreciate it. The samples I've found havn't been much use; they seem to be directed to showing off cool stuff (Twitter, weather.com) rather than actual work. Thanks in advance.

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  • Why would I be seeing execution timeouts when setting $_SESSION values?

    - by Kev
    I'm seeing the following errors in my PHP error logs: PHP Fatal error: Maximum execution time of 60 seconds exceeded in D:\sites\s105504\www\index.php on line 3 PHP Fatal error: Maximum execution time of 60 seconds exceeded in D:\sites\s105504\www\search.php on line 4 The lines in question are: index.php: 01 <?php 02 session_start(); 03 ob_start(); 04 error_reporting(E_All); 05 $_SESSION['nav'] = "range"; // <-- Error generated here search.php 01 <?php 02 03 session_start(); 04 $_SESSION['nav'] = "range"; 05 $_SESSION['navselected'] = 21; // <-- Error generated here Would it really take as long as 60+ seconds to assign a $_SESSION[] value? The platform is: Windows 2003 SP2 + IIS6 FastCGI for Windows 2003 (original RTM build) PHP 5.2.6 Non thread-safe build There aren't any issues with session data files being cleared up on the server as sessions expire. The oldest sess_XXXXXXXXXXXXXX file I'm seeing is around 2 hours old. There are no disk timeouts evident in the event logs or other such disk health issues that might suggest difficulty creating session data files. The site is also on a server that isn't under heavy load. The site is busy but not being hammered and is very responsive. It's just that we get these errors, three or four in a row, every three or four hours. I should also add that I'm not the original developer of this code and that it belongs to a customer who's developer has long since departed.

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  • Why did instruments report a leak while its ref count did become zero

    - by bromj
    Hello guys, green hand i am. I'm using instruments, and it did a great help to me so far, but I'm confused now 'cause it report a memory leak to me while its leaked block history shows me that the ref count of that memory had finally become 0. What does it mean? It's really embarrassing that I couldn't post a image here... so I have to describe it in text. Hope it would be clear enough for you: Event Type || RefCt || Responsible Library || Responsible Caller Malloc         || 1        || MyWeather              || +[ForecastData parseSingleForecastWithXMLElement:] Autorelease||           || MyWeather              || +[ForecastData parseSingleForecastWithXMLElement:] Retain         || 2        || MyWeather              || +[ForecastData parseWithData:] Release      || 1        || Foundation              || +[NSAutoreleasePool drain:] Retain         || 2        || Foundation              || +[NSThread initWithTarget:selector:object:] Release      || 1        || Foundation              || +[NSString compare:options:] Release      || 0        || MyWeather              || +[RootViewController dealloc] Any help will be appreciated~

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  • C# parameters by reference and .net garbage collection

    - by Yarko
    I have been trying to figure out the intricacies of the .NET garbage collection system and I have a question related to C# reference parameters. If I understand correctly, variables defined in a method are stored on the stack and are not affected by garbage collection. So, in this example: public class Test { public Test() { } public int DoIt() { int t = 7; Increment(ref t); return t; } private int Increment(ref int p) { p++; } } the return value of DoIt() will be 8. Since the location of t is on the stack, then that memory cannot be garbage collected or compacted and the reference variable in Increment() will always point to the proper contents of t. However, suppose we have: public class Test { private int t = 7; public Test() { } public int DoIt() { Increment(ref t); return t; } private int Increment(ref int p) { p++; } } Now, t is stored on the heap as it is a value of a specific instance of my class. Isn't this possibly a problem if I pass this value as a reference parameter? If I pass t as a reference parameter, p will point to the current location of t. However, if the garbage collector moves this object during a compact, won't that mess up the reference to t in Increment()? Or does the garbage collector update even references created by passing reference parameters? Do I have to worry about this at all? The only mention of worrying about memory being compacted on MSDN (that I can find) is in relation to passing managed references to unmanaged code. Hopefully that's because I don't have to worry about any managed references in managed code. :)

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  • Combining cache methods - memcache/disk based

    - by Industrial
    Hi! Here's the deal. We would have taken the complete static html road to solve performance issues, but since the site will be partially dynamic, this won't work out for us. What we have thought of instead is using memcache + eAccelerator to speed up PHP and take care of caching for the most used data. Here's our two approaches that we have thought of right now: Using memcache on all<< major queries and leaving it alone to do what it does best. Usinc memcache for most commonly retrieved data, and combining with a standard harddrive-stored cache for further usage. The major advantage of only using memcache is of course the performance, but as users increases, the memory usage gets heavy. Combining the two sounds like a more natural approach to us, even though the theoretical compromize in performance. Memcached appears to have some replication features available as well, which may come handy when it's time to increase the nodes. What approach should we use? - Is it stupid to compromize and combine the two methods? Should we insted be focusing on utilizing memcache and instead focusing on upgrading the memory as the load increases with the number of users? Thanks a lot!

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  • How to migrate primary key generation from "increment" to "hi-lo"?

    - by Bevan
    I'm working with a moderate sized SQL Server 2008 database (around 120 tables, backups are around 4GB compressed) where all the table primary keys are declared as simple int columns. At present, primary key values are generated by NHibernate with the increment identity generator, which has worked well thus far, but precludes moving to a multiprocessing environment. Load on the system is growing, so I'm evaluating the work required to allow the use of multiple servers accessing a common database backend. Transitioning to the hi-lo generator seems to be the best way forward, but I can't find a lot of detail about how such a migration would work. Will NHibernate automatically create rows in the hi-lo table for me, or do I need to script these manually? If NHibernate does insert rows automatically, does it properly take account of existing key values? If NHibernate does take care of thing automatically, that's great. If not, are there any tools to help? Update NHibernate's increment identifier generator works entirely in-memory. It's seeded by selecting the maximum value of used identifiers from the table, but from that point on allocates new values by a simple increment, without reference back to the underlying database table. If any other process adds rows to the table, you end up with primary key collisions. You can run multiple threads within the one process just fine, but you can't run multiple processes. For comparison, the NHibernate identity generator works by configuring the database tables with identity columns, putting control over primary key generation in the hands of the database. This works well, but compromises the unit of work pattern. The hi-lo algorithm sits inbetween these - generation of primary keys is coordinated through the database, allowing for multiprocessing, but actual allocation can occur entirely in memory, avoiding problems with the unit of work pattern.

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  • Java/XML: Good "Stream-based" Alternative to JAXB?

    - by Jan
    Hello Experts, JAXB makes working with XML so much easier, but I have currently a big problem, that the documents I have to process are too large for an in memory unmarshalling that JAXB does. The data can be up to 4GB per document. The datastructure I will have to process is very simple and flat: With a root element and millions of “elements”… <root> <element> <sub>foo</sub> </element> <element> <sub>foo</sub> </element> </root> May questions are: Does JAXB maybe somehow support unmarshalling in a “streambased” way, that does not require to build the whole objecttree in memory but rather gives me some kind of “Iterator” to the elements, element by element? (Maybe I just missed that somehow…) If not what are your proposals for an good alternative with a a. “flat learningcurve, ideally very similar to JAXB b. AND VERY IMPORTANT: Ideally with the possibility / tool for the generation of the unarshaller code from an XSD file OR annotated Java Class 3.(I have searched SO and those to library that ended up on my “watchlist” (without comparing them closer) were Apache XML Beans and Xstream… What other libraries are maybe even better for the purpose and what are the disadvantages, adavangaes… Thank you very much!!! Jan

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  • Center a TextBox over the top of a ScrollViewer in WPF.

    - by Eric
    I have a MainView that contains a navigation bar which selects one of many XAML pages to be displayed in the page view pane. The MainView contains a ScrollViewer around the pages. This allows the pages to be whatever size they need to be and the MainView's ScrollViewer scrolls them. This all works great. On one of the pages, I need to (sometimes) center a TextBox in the middle of the page view pane (over the top of the page content). This was easily done by placing both the page content and the TextBox overlapping each other in a Grid (and I hide the TextBox as necessary). This all seems to work great. However, if the page content grows to be larger than the pane, the TextBox is centered not on the pane, but on the full page content. Thus, it moves from center screen down and/or to the right (and eventually off the screen). Bummer. Options: Remove the ScrollViewer from the MainView. This would require placing one on every page! Argh. Do option #1, and create a ScrolledPage base class. This is a lot of work, and I'm worried about tools issues (Blend issues). It also requires changing every page (to subclass this page). Somehow override the ScrollViewer on just this page. Then, place another ScrollViewer on the page content to Scroll it. Option 3 seems preferable, because it contains the issue to just modifying this page (instead of changing the rest of the pages). However, I can't figure out how to do it. Ideas? Thanks in advance! Eric

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  • Java Random Slowdowns on Mac OS cont'd

    - by javajustice
    I asked this question a few weeks ago, but I'm still having the problem and I have some new hints. The original question is here: http://stackoverflow.com/questions/1651887/java-random-slowdowns-on-mac-os Basically, I have a java application that splits a job into independent pieces and runs them in separate threads. The threads have no synchronization or shared memory items. The only resources they do share are data files on the hard disk, with each thread having an open file channel. Most of the time it runs very fast, but occasionally it will run very slow for no apparent reason. If I attach a CPU profiler to it, then it will start running quickly again. If I take a CPU snapshot, it says its spending most of its time in "self time" in a function that doesn't do anything except check a few (unshared unsynchronized) booleans. I don't know how this could be accurate because 1, it makes no sense, and 2, attaching the profiler seems to knock the threads out of whatever mode they're in and fix the problem. Also, regardless of whether it runs fast or slow, it always finishes and gives the same output, and it never dips in total cpu usage (in this case ~1500%), implying that the threads aren't getting blocked. I have tried different garbage collectors, different sizings the parts of the memory space, writing data output to non-raid drives, and putting all data output in threads separate the main worker threads. Does anyone have any idea what kind of problem this could be? Could it be the operating system (OS X 10.6.2) ? I have not been able to duplicate it on a windows machine, but I don't have one with a similar hardware configuration.

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  • Android, how to use DexClassLoader to dynamically replace an Activity or Service

    - by RickNotFred
    I am trying to do something similar to this stackoverflow posting. What I want to do is to read the definition of an activity or service from the SD card. To avoid manifest permission issues, I create a shell version of this activity in the .apk, but try to replace it with an activity of the same name residing on the SD card at run time. Unfortunately, I am able to load the activity class definition from the SD card using DexClassLoader, but the original class definition is the one that is executed. Is there a way to specify that the new class definition replaces the old one, or any suggestions on avoiding the manifest permission issues without actually providing the needed activity in the package? The code sample: ClassLoader cl = new DexClassLoader("/sdcard/mypath/My.apk", getFilesDir().getAbsolutePath(), null, MainActivity.class.getClassLoader()); try { Class<?> c = cl.loadClass("com.android.my.path.to.a.loaded.activity"); Intent i = new Intent(getBaseContext(), c); startActivity(i); } catch (Exception e) { Intead of launching the com.android.my.path.to.a.loaded.activity specified in /sdcard/mypath/My.apk, it launches the activity statically loaded into the project.

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  • sql-server performance optimization by removing print statements

    - by AG
    We're going through a round of sql-server stored procedure optimizations. The one recommendation we've found that clearly applies for us is 'SET NOCOUNT ON' at the top of each procedure. (Yes, I've seen the posts that point out issues with this depending on what client objects you run the stored procedures from but these are not issues for us.) So now I'm just trying to add in a bit of common sense. If the benefit of SET NOCOUNT ON is simply to reduce network traffic by some small amount every time, wouldn't it also make sense to turn off all the PRINT statements we have in the stored procedures that we only use for debugging? I can't see how it can hurt performance. OTOH, it's a bit of a hassle to implement due to the fact that some of the print statements are the only thing within else clauses, so you can't just always comment out the one line and be done. The change carries some amount of risk so I don't want to do it if it isn't going to actually help. But I don't see eliminating print statements mentioned anywhere in articles on optimization. Is that because it is so obvious no one bothers to mention it?

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  • How to genrate a monochrome bit mask for a 32bit bitmap

    - by Mordachai
    Under Win32, it is a common technique to generate a monochrome bitmask from a bitmap for transparency use by doing the following: SetBkColor(hdcSource, clrTransparency); VERIFY(BitBlt(hdcMask, 0, 0, bm.bmWidth, bm.bmHeight, hdcSource, 0, 0, SRCCOPY)); This assumes that hdcSource is a memory DC holding the source image, and hdcMask is a memory DC holding a monochrome bitmap of the same size (so both are 32x32, but the source is 4 bit color, while the target is 1bit monochrome). However, this seems to fail for me when the source is 32 bit color + alpha. Instead of getting a monochrome bitmap in hdcMask, I get a mask that is all black. No bits get set to white (1). Whereas this works for the 4bit color source. My search-foo is failing, as I cannot seem to find any references to this particular problem. I have isolated that this is indeed the issue in my code: i.e. if I use a source bitmap that is 16 color (4bit), it works; if I use a 32 bit image, it produces the all-black mask. Is there an alternate method I should be using in the case of 32 bit color images? Is there an issue with the alpha channel that overrides the normal behavior of the above technique? Thanks for any help you may have to offer! ADDENDUM: I am still unable to find a technique that creates a valid monochrome bitmap for my GDI+ produced source bitmap. I have somewhat alleviated my particular issue by simply not generating a monochrome bitmask at all, and instead I'm using TransparentBlt(), which seems to get it right (but I don't know what they're doing internally that's any different that allows them to correctly mask the image). It might be useful to have a really good, working function: HBITMAP CreateTransparencyMask(HDC hdc, HBITMAP hSource, COLORREF crTransparency); Where it always creates a valid transparency mask, regardless of the color depth of hSource. Ideas?

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  • Good guidelines for developing an ecommerce application

    - by kaciula
    I'm making an ecommerce application on Android and, as it is my first serious project, I'm trying to figure out beforehand the best approach to do this. The application talks to a web service (magento api, meaning soap or xml rpc unfortunately) and gets all the content on the phone (product categories, product details, user credentials etc.). I think it should do lazy loading or something like that. So, I was thinking to keep the user credentials in a custom Object which will be kept in a SharedPreferences so that every Activity cand easily access it. I'll use a couple of ListViews to show the content and AsyncTask to fetch the data needed. Should I keep all the data in memory in objects or should I use some sort of cache or a local database? Also, I'm planning to use a HashMap with SoftReferences to hold the bitmaps I am downloading. But wouldn't this eat a lot of memory? How cand all the activities have access to all these objects (ecommerce basket etc.)? I'm thinking of passing them using Intents but this doesn't seem right to me. Can SharedPreferences be used for a lot of objects and are there any concurrency issues? Any pointers would be really appreciated. What are some good guidelines? What classes should I look into? Do you know of any resources on the Internet for me to check out?

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  • Is XMLReader a SAX parser, a DOM parser, or neither?

    - by Renesis
    I am testing various methods to read (possibly large, and very often) XML configuration files in PHP. No writing is ever needed. I have two successful implementations, one using SimpleXML (which I know is a DOM parser) and one using XMLReader. I know that a DOM reader must read the whole tree and therefore uses more memory. My tests reflect that. I also know that A SAX parser is an "event-based" parser that uses less memory because it reads each node from the stream without checking what is next. XMLReader also reads from a stream with the cursor providing data about the node it is currently at. So, it definitely sounds like XMLReader (http://us2.php.net/xmlreader) is not a DOM parser, but my question is, is it a SAX parser, or something else? It seems like XMLReader behaves the way a SAX parser does but does not throw the events themselves (in other words, can you construct a SAX parser with XMLReader?) If it is something else, does the classification it's in have a name?

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  • Volatile fields in C#

    - by Danny Chen
    From the specification 10.5.3 Volatile fields: The type of a volatile field must be one of the following: A reference-type. The type byte, sbyte, short, ushort, int, uint, char, float, bool, System.IntPtr, or System.UIntPtr. An enum-type having an enum base type of byte, sbyte, short, ushort, int, or uint. First I want to confirm my understanding is correct: I guess the above types can be volatile because they are stored as a 4-bytes unit in memory(for reference types because of its address), which guarantees the read/write operation is atomic. A double/long/etc type can't be volatile because they are not atomic reading/writing since they are more than 4 bytes in memory. Is my understanding correct? And the second, if the first guess is correct, why a user defined struct with only one int field in it(or something similar, 4 bytes is ok) can't be volatile? Theoretically it's atomic right? Or it's not allowed simply because that all user defined structs(which is possibly more than 4 bytes) are not allowed to volatile by design?

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  • On-Demand thumbnail creation with django and nginx

    - by sharjeel
    I want to generate thumbnails of images on the fly. My site is built with django and deployed using nginx which serves all the static content and communicates with django/apache using reverse proxy. Right now, for every image in my site, I generate all required sizes of thumbnails on-hand and deliver them when required. The problem is that whenever I change the size of a thumbnail, I have to regenerate all of them (and they are tons). However now I'd like to generate the thumbnail the first time it is accessed and later on nginx would deliver the same file over n over. If I delete that thumbnail file because of lesser accesses, it should get generated automatically the next time. Thumbnails in my case also have watermarks which require some computation logic of my application so a webserver thumbnail module might not work very well. The size of the thumbnail can be embedded in the URL. So http://www.example.com/thumbnail/abc_320x240.jpg gets the 320x240 size of the thumbnail. The approach I'm looking right now is to let nginx lookup the file and if it doesn't exist, forward the query to my django application which would create the thumbnail and send either the response or a redirect string. However I'm not sure about the concurrency issues and any other issues which might pop up later. What is the appropriate way to achieve this?

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  • An array of LPWSTR pointers, not working right.

    - by BigBirdy
    Declare: LPWSTR** lines= new LPWSTR*[totalLines]; then i set using: lines[totalLines]=&totalText; SetWindowText(totalChat,(LPWSTR)lines[totalLines]); totalLines++; Now I know totalText is right, cause if i SetWindowText using totalText it works fine. I need the text in totalLines too. I'm also doing: //accolating more memory. int orgSize=size; LPWSTR** tempArray; if (totalLines == size) { size *= 2; tempArray = new LPWSTR*[size]; memcpy(tempArray, lines,sizeof(LPWSTR)*orgSize); delete [] lines; lines = tempArray; } to allocate more memory when needed. My problem is that the lines is not getting the right data. It works for the first time around then it get corrupted. I thought at first i was overwriting but totalLines is increase. Hopefully this is enough information.

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  • gen_server with a dict vs mnesia table vs ets

    - by pablo
    Hi, I'm building an erlang server. Users sends http requests to the server to update their status. The http request process on the server saves the user status message in memory. Every minute the server sends all messages to a remote server and clear the memory. If a user update his status several times in a minute, the last message overrides the previous one. It is important that between reading all the messages and clearing them no other process will be able to write a status message. What is the best way to implement it? gen_server with a dict. The key will be the userid. dict:store/3 will update or create the status. The gen_server solves the 'transaction' issue. mnesia table with ram_copies. Handle transactions and I don't need to implement a gen_server. Is there too much overhead with this solution? ETS table which is more light weight and have a gen_server. Is it possible to do the transaction in ETS? To lock the table between reading all the messages and clearing them? Thanks

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  • Is there a way to use Linq projections with extension methods

    - by Acoustic
    I'm trying to use AutoMapper and a repository pattern along with a fluent interface, and running into difficulty with the Linq projection. For what it's worth, this code works fine when simply using in-memory objects. When using a database provider, however, it breaks when constructing the query graph. I've tried both SubSonic and Linq to SQL with the same result. Thanks for your ideas. Here's an extension method used in all scenarios - It's the source of the problem since everything works fine without using extension methods public static IQueryable<MyUser> ByName(this IQueryable<MyUser> users, string firstName) { return from u in users where u.FirstName == firstName select u; } Here's the in-memory code that works fine var userlist = new List<User> {new User{FirstName = "Test", LastName = "User"}}; Mapper.CreateMap<User, MyUser>(); var result = (from u in userlist select Mapper.Map<User, MyUser>(u)) .AsQueryable() .ByName("Test"); foreach (var x in result) { Console.WriteLine(x.FirstName); } Here's the same thing using a SubSonic (or Linq to SQL or whatever) that fails. This is what I'd like to make work somehow with extension methods... Mapper.CreateMap<User, MyUser>(); var result = from u in new DataClasses1DataContext().Users select Mapper.Map<User, MyUser>(u); var final = result.ByName("Test"); foreach(var x in final) // Fails here when the query graph built. { Console.WriteLine(x.FirstName); } The goal here is to avoid having to manually map the generated "User" object to the "MyUser" domain object- in other words, I'm trying to find a way to use AutoMapper so I don't have this kind of mapping code everywhere a database read operation is needed: var result = from u in new DataClasses1DataContext().Users select new MyUser // Can this be avoided with AutoMapper AND extension methods? { FirstName = v.FirstName, LastName = v.LastName };

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