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  • How does multiple implementing multiple COM interfaces work in C++?

    - by Martin
    I am trying to understand this example code regarding Browser Helper Objects. Inside, the author implements a single class which exposes multiple interfaces (IObjectWithSite, IDispatch). His QueryInterface function performs the following: if(riid == IID_IUnknown) *ppv = static_cast<BHO*>(this); else if(riid == IID_IObjectWithSite) *ppv = static_cast<IObjectWithSite*>(this); else if (riid == IID_IDispatch) *ppv = static_cast<IDispatch*>(this); I have learned that from a C perspective, interface pointers are just pointers to VTables. So I take it to mean that C++ is capable of returning the VTable of any implemented interface using static_cast. Does this mean that a class constructed in this way has a bunch of VTables in memory (IObjectWithSite, IDispatch, etc)? What does C++ do with the name collisions on the different interfaces (they each have a QueryInterface, AddRef and Release function), can I implement different methods for each of these?

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  • How to implement arrays in an interpreter?

    - by Ray
    I have managed to write several interpreters including Tokenizing Parsing, including more complicated expressions such as ((x+y)*z)/2 Building bytecode from syntax trees Actual bytecode execution What I didn't manage: Implementation of dictionaries/lists/arrays. I always got stuck with getting multiple values into one variable. My value structure (used for all values passed around, including variables) looks like this, for example: class Value { public: ValueType type; int integerValue; string stringValue; } Works fine with integers and strings, but how could I implement arrays? (From now on with array I mean arrays in my experimental language, not in C++) How can I fit the array concept into the Value class above? Is it possible? How should I make arrays able to be passed around just as you could pass around integers and strings in my language, using the class above? Accessing array elements or memory allocation wouldn't be the problem, I just don't know how to store them.

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  • What libraries are available for manipulating super large images in .Net

    - by tpower
    I have some really large files for example 320 MB tif file with 14000 X 9000 pixels. The operations I need to perform are basically scaling the images to get smaller versions of it and breaking the image into tiles. My code works fine with small files and I use the .Net Bitmap objects but I will occasionally get Out of Memory exceptions for larger files. I've tried using the FreeImage libraries FreeImageBitmap but have the same problems. I'm using something like the following to scale the image: using (Graphics g = Graphics.FromImage((Image)result)) { g.DrawImage( source, xOffset, yOffset, source.Width * scale, source.Height * scale ); } Ideally I'd like a third party library to do all the hardwork, but if you have any tips or resources with more information I would appreciate it.

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  • Large ResultSet on postgresql query

    - by tuler
    I'm running a query against a table in a postgresql database. The database is on a remote machine. The table has around 30 sub-tables using postgresql partitioning capability. The query will return a large result set, something around 1.8 million rows. In my code I use spring jdbc support, method JdbcTemplate.query, but my RowCallbackHandler is not being called. My best guess is that the postgresql jdbc driver (I use version 8.3-603.jdbc4) is accumulating the result in memory before calling my code. I thought the fetchSize configuration could control this, but I tried it and nothing changes. I did this as postgresql manual recomended. This query worked fine when I used Oracle XE. But I'm trying to migrate to postgresql because of the partitioning feature, which is not available in Oracle XE. My environment: Postgresql 8.3 Windows Server 2008 Enterprise 64-bit JRE 1.6 64-bit Spring 2.5.6 Postgresql JDBC Driver 8.3-603

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  • Object sent -autorelease too many times

    - by mongeta
    I have this code that simple returns Today's date as a string formatted: +(NSString*) getTodayString_YYYY_MM_DD { NSDate * today = [NSDate date]; NSDateFormatter *formatter = [[NSDateFormatter alloc] init]; [formatter setDateFormat:@"yyyy-MM-dd"]; return [[formatter stringFromDate:today] autorelease]; } With instruments I'm not getting a memory leak, but when I Analyze, XCode says: Object sent -autorelease too many times If I understand correctly, I have to release manually the formatter as I'm creating it using 'alloc', but I can't release here because I have to return the value, so I add the autorelease. How I can do it better to improve it ? thanks, r.

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  • SQLserver multithreaded locking with TABLOCKX

    - by WilfriedVS
    I have a table "tbluser" with 2 fields: userid = integer (autoincrement) user = nvarchar(100) I have a multithreaded/multi server application that uses this table. I want to accomplish the following: Guarantee that field user is unique in my table Guarantee that combination userid/user is unique in each server's memory I have the following stored procedure: CREATE PROCEDURE uniqueuser @user nvarchar(100) AS BEGIN BEGIN TRAN DECLARE @userID int SET nocount ON SET @userID = (SELECT @userID FROM tbluser WITH (TABLOCKX) WHERE [user] = @user) IF @userID <> '' BEGIN SELECT userID = @userID END ELSE BEGIN INSERT INTO tbluser([user]) VALUES (@user) SELECT userID = SCOPE_IDENTITY() END COMMIT TRAN END Basically the application calls the stored procedure and provides a username as parameter. The stored procedure either gets the userid or insert the user if it is a new user. Am I correct to assume that the table is locked (only one server can insert/query)?

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  • How to read a file with variable multi-row data in Python

    - by dr.bunsen
    I have a file that is about 100Mb that looks like this: #meta data 1 skadjflaskdjfasljdfalskdjfl sdkfjhasdlkgjhsdlkjghlaskdj asdhfk #meta data 2 jflaksdjflaksjdflkjasdlfjas ldaksjflkdsajlkdfj #meta data 3 alsdkjflasdjkfglalaskdjf This file contains one row of meta data that corresponds to several, variable length data containing only alpha-numeric characters. What is the best way to read this data into a simple list like this: data = [[#meta data 1, skadjflaskdjfasljdfalskdjflsdkfjhasdlkgjhsdlkjghlaskdjasdhfk], [#meta data 2, jflaksdjflaksjdflkjasdlfjasldaksjflkdsajlkdfj], [#meta data 3, alsdkjflasdjkfglalaskdjf]] My initial idea was to use the read() method to read the whole file into memory and then use regular expressions to parse the data into the desired format. Is there a better more pythonic way? All metadata lines start with an octothorpe and all data lines are all alpha-numeric. Thanks!

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  • Plugin architecture in .net: unloading

    - by henchman
    Hello everybody, I need to implement a plugin architecture within c#/.net in order to load custom user defined actions data type handling code for a custom data grid / conversion / ... from non-static linked assembly files. Because the application has to handle many custom user defined actions, Iam in need for unloading them once executed in order to reduce memory usage. I found several good articles about plugin architectures, eg: ExtensionManager PluginArchitecture ... but none of them gave me enough sausage for properly unloading an assembly. As the program is to be distributed and the user defined actions are (as the name states) user defined: how to i prevent the assembly from executing malicious code (eg. closing my progra, deleting files)? Are there any other pitfalls one of you has encountered?

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  • How to index a string like "aaa.bbb.ddd-fff" in Lucene?

    - by user46703
    Hi, I have to index a lot documents that contain reference numbers like "aaa.bbb.ddd-fff". The structure can change but it's always some arbitrary numbers or characters combined with "/","-","_" or some other delimiter. The users want to be able to search for any of the substrings like "aaa" or "ddd" and also for combinations like "aaa.bbb" or "ddd-fff". The best I have been able to come up with is to create my own token filter modeled after the synonym filter in "Lucene in action" which spits out multiple terms for each input. In my case I return "aaa.bbb", "bbb.ddd","bbb.ddd-fff" and all other combinations of the substrings. This works pretty well but when I index large documents (100MB) that contain lots of such strings I tend to get out of memory exceptions because my filter returns multiple terms for each input string. Is there a better way to index these strings?

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  • How to reduce java concurrent mode failure and excessive gc

    - by jimx
    In Java, the concurrent mode failure means that the concurrent collector failed to free up enough memory space form tenured and permanent gen and has to give up and let the full stop-the-world gc kicks in. The end result could be very expensive. I understand this concept but never had a good comprehensive understanding of A) what could cause a concurrent mode failure and B) what's the solution?. This sort of unclearness leads me to write/debug code without much of hints in mind and often has to shop around those performance flags from Foo to Bar without particular reasons, just have to try. I'd like to learn from developers here how your experience is. If you had previous encountered such performance issue, what was the cause and how you addressed it? If you have coding recommendations, please don't be too general. Thanks!

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  • Returning references while using shared_ptrs

    - by Goose Bumper
    Suppose I have a rather large class Matrix, and I've overloaded operator== to check for equality like so: bool operator==(Matrix &a, Matrix &b); Of course I'm passing the Matrix objects by reference because they are so large. Now i have a method Matrix::inverse() that returns a new Matrix object. Now I want to use the inverse directly in a comparison, like so: if (a.inverse()==b) { ... }` The problem is, this means the inverse method needs to return a reference to a Matrix object. Two questions: Since I'm just using that reference in this once comparison, is this a memory leak? What happens if the object-to-be-returned in the inverse() method belongs to a boost::shared_ptr? As soon as the method exits, the shared_ptr is destroyed and the object is no longer valid. Is there a way to return a reference to an object that belongs to a shared_ptr?

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  • Chaning coding style due to Android GC performance, how far is too far?

    - by Benju
    I keep hearing that Android applications should try to limit the number of objects created in order to reduce the workload on the garbage collector. It makes sense that you may not want to created massive numbers of objects to track on a limited memory footprint, for example on a traditional server application created 100,000 objects within a few seconds would not be unheard of. The problem is how far should I take this? I've seen tons of examples of Android applications relying on static state in order supposedly "speed things up". Does increasing the number of instances that need to be garbage collected from dozens to hundreds really make that big of a difference? I can imagine changing my coding style to now created hundreds of thousands of objects like you might have on a full-blown Java-EE server but relying on a bunch of static state to (supposedly) reduce the number of objects to be garbage collected seems odd. How much is it really necessary to change your coding style in order to create performance Android apps?

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  • addObjectsFromArray

    - by derek.lo
    I have a question about memory management when using the addObjectsFromArray method. Basically, I have 2 arrays defined in the appDelegate. I need these 2 arrays for the duration of my application's runtime. I therefore release them in my appDelegate's dealloc method. When I go to use these two arrays in a class, I want one array to store the values from the other, so that the other can have it's contents removed, but still stick around for use. Something like this: [appDelegate.arrayTwo addObjectsFromArray:appDelegate.arrayOne]; [appDelegate.arrayOne removeAllObjects]; I'm getting the compiler error: EXC_BAD_ACCESS because of a pointer issue? retaining issue? Any help would be greatly appreciated! Thanks

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  • Conseqences of assigning self

    - by Vegar
    Hi, Found a piece of code today, that I find a little smelly... TMyObject.LoadFromFile(const filename: String); begin if fileExists(filename) then self := TSomeObjectStreamer.ReadObjectFromFile(filename); end; If this code works, it will atleast leak some memory, but does it work? Is OK to assign to self in this manner? What if the streamed object is of a different subclass then the original self? What if the streamed object is of a different class with no common ancestore to the original self?

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  • How can I catch runtime error in C++

    - by Yan Cheng CHEOK
    By referring to http://stackoverflow.com/questions/315948/c-catching-all-exceptions try { int i = 0; int j = 0/i; /* Division by 0 */ int *k = 0; std::cout << *k << std::endl; /* De-reference invalid memory location. */ } catch (...) { std::cout << "Opps!" << std::endl; } The above run-time error are unable to be detected. Or, am I having wrong expectation on C++ exception handling feature?

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  • How can I change how OS X's 'say' command pronounces a word?

    - by jwhitlock
    OS X's say command is useful for some tasks (such as Skype's 'notify me when a contact comes online), but it is pronouncing some names incorrectly. Is there a way to teach say to pronounce a word differently? For example, try: say "Hi, Joel Spolsky" The 'ol' sounds like 'ball' rather than 'old'. I'd like to add an exception that say "Pronounce Spolsky like this", rather than try to teach new linguistic rules. I bet there is a way since it can pronounce "iphone" as Apple wants. Update - After some research, here's what I've learned: Text-to-speech is split between turning the text to phonemes, and then the phonemes are turned into audio using a voice. Changing the voice doesn't effect the phonemes. The Speech Synthesis Manager has some functions for turning text to phonemes, and a method for registering a speech dictionary that will add new text-phoneme maps. However, Apple's speech dictionary must be in a binary form - I didn't find any plist XML. Using dtrace while running say, I found some interesting files opened in /System/Library/PrivateFrameworks/SpeechDictionary.framework/Resources. This is probably the speech dictionary, but they are all binary, except for Homophones, which is XML. Adding entries to Homophones does nothing - it is probably used in speech-to-text. They are also code signed by Apple - changing them may prevent some programs from working. PrefixDictionary CartNames CartLite SymbolDictionary Homophones There are ways to add text versions of application interface elements so VoiceOver works, a lot of which a developer gets for free, but there are tricky bits. The standard here appears to be to use a phonetic spelling as needed. My guesses are: say is a light layer of code on top of the Speech Synthesis Manager. It would be easy for the Apple devs to add a command line option to take the path to a speech dictionary plist for alternate phoneme mapping, but they didn't. It may be a useful open-source project to write a better say. Skype probably uses Speech Synthesis Manager directly, leaving no hooks to change the way my friend's names are pronounced, other than spelling them phonetically, which is silly. The easiest way to make a command line version of say is how JRobert suggested. Here's my quick implementation, using Doug Harris's spelling suggestion: #!/bin/sh echo $@ | tr '[A-Z]' '[a-z]' | sed "s/spolsky/spowlsky/g" | /usr/bin/say Finally, some fun command line stuff: # Apple is weird sqlite3 /System/Library/PrivateFrameworks/SpeechDictionary.framework/Resources/Tuples .dump # Get too much information about what files are being opened sudo dtrace -n 'syscall::open*:entry { printf("%s %s",execname,copyinstr(arg0)); }' # Just fun say -v bad "Joel Spolsky Spolsky Spolsky Spolsky Spolsky, Joel Spolsky Spolsky Spolsky Spolsky Spolsky" echo "scale=1000; 4*a(1)" | bc -l | say

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  • Changes to the User Permissions Not saving

    - by anru
    I am use drupal 6. it seems like permission page can not save too many settings. I have try to save permission setting, but it is just not saved into DB. I have found out this is due to "too many fields". (use content permission module). if i uncheck some fields, and then checking lesser fields, permission will be saved. for example, if I am unchecking 2 check boxes, then checking one check box, permission will be saved. does any one know which function the permission page used to insert result into db? my php memory limit is 256M.

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  • Are there any Python reference counting/garbage collection gotchas when dealing with C code?

    - by Jason Baker
    Just for the sheer heck of it, I've decided to create a Scheme binding to libpython so you can embed Python in Scheme programs. I'm already able to call into Python's C API, but I haven't really thought about memory management. The way mzscheme's FFI works is that I can call a function, and if that function returns a pointer to a PyObject, then I can have it automatically increment the reference count. Then, I can register a finalizer that will decrement the reference count when the Scheme object gets garbage collected. I've looked at the documentation for reference counting, and don't see any problems with this at first glance (although it may be sub-optimal in some cases). Are there any gotchas I'm missing? Also, I'm having trouble making heads or tails of the cyclic garbage collector documentation. What things will I need to bear in mind here? In particular, how do I make Python aware that I have a reference to something so it doesn't collect it while I'm still using it?

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  • Converting MS Word Documents to PDF in ASP.NET

    - by glaxaco
    Similar questions have been asked, but nothing exactly like mine, so here goes. We have a collection of Microsoft Word documents on an ASP.NET web server with merge fields whose values are filled in as a result of user form submissions. After the field merge, the server must convert the document to PDF and stream it down to the browser. Our first inclination was to use the Visual Studio Tools for Office API; however, we ran into this warning from Microsoft: Microsoft does not currently recommend, and does not support, Automation of Microsoft Office applications from any unattended, non-interactive client application or component (including ASP, ASP.NET, DCOM, and NT Services), because Office may exhibit unstable behavior and/or deadlock when Office is run in this environment. It looks like the field manipulation can be done using the Open XML SDK, but what's the best way to convert Word 2007 documents to PDF without opening Word? The optimal solution would be low-cost, scalable, have a low memory footprint, be easy to deploy, and have a .NET API.

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  • How to solve the performance decay of a VB.NET 1.1 application?

    - by marco.ragogna
    I have single-thread windows form application written with VB.NET and targeting Framework 1.1. The software communicates with external boards through a serial interface, and it mainly consist of a state machine that run some tests, driven in a loop done with a Timer and an Interval of 50ms. The feedback on the user interface is done through some custom events raised during the tests. The problem that is driving me crazy is that the performance slightly decrease over time, and in particular after 1200/1300 test operations. The memory occupied does not increase over time, it is only the CPU that seems interested by this problem. The strange thing is that, targeting framework 2.0 and using the same identical code, I do not have this problem. I know that is difficult without looking at the code, but do you have suggestions how can I approach the problem?

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  • PHP: how to stop ignore_user_abort, is it a good solution for long run program

    - by user192344
    let say i have send email program which need to run arround 7 hours. but i cant open the browser for 7 hours beside cronjob, ignore_user_abort() will it be a solution? will the script stop when all email has sent and the program has finish the loop? or it will keep eating the server memory? some people said u may need to add some output at the end of the program to avoid the program run forever? and some people also said echo a litte bit string will not stop the script, but has to use ob_flush, any example for this?

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  • WCF high instance count: anyone knows negative sideffects?

    - by Alex
    Hi there! Did anyone experience or know of negative side effects from having a high service instance count like 60k? Aside from the memory consumption of course. I am planning to increase the threshold for the maximum allowed instance count in our production environments. I am basically sick of severe production incidents just because "something" forgot to close a proxy properly. I plan to go to something like 60k instances which will allow the service to survive using default session timeouts at a call rate average for our clients. Thanks, Alex

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  • Parsing XML stream in ASP.NET 3.5

    - by Ranjit
    Hi All, I am trying to build an ASP.NET 3.5 application based on XML streams from a legacy systems. My issue is once I get the XML I have to built menus and sub menus from the XML as well filter data(XML stream) based on the menu selection without making roundtrip to the Data store(legacy system). Right now I have a DAL which will get the XML stream in the form of XDocument.I was able to built the first level Menu Items, but not the sub Menu Items based on the selection in the Main Menu and then the final content based on the sub menu selection, all this without making a round trip. Is there a way to do this in-memory. Please suggest. thank you. Ranjit

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  • What is a .NET managed module?

    - by Abhijeet Patel
    I know it's a Windows PE32, but I also know that the unit of deployment in .NET is an assembly which in turn has a manifest and can be made up of multiple managed modules. My questions are : 1) How would you create multiple managed modules when building a project such as a class lib or a console app etc. 2) Is there a way to specify this to the compiler(via the project properties for example) to partition your source code files into multiple managed modules. If so what is the benefit of doing so? 3)Can managed modules span assemblies? 4)Are separate file created on disk when the source code is compiled or are these created in memory and directly embedded in an assembly?

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  • translating ROI code in c#

    - by sayyad
    Hi, I am trying to translate this code in c# using emgucv. I have some questions.Could yome body help me line by line. cvSetImageROI(img1, cvRect(10, 15, 150, 250)); I have four points (PoinstF). Should I calculate rectangle or there is some way with four points. CvInvoke.cvSetImageROI(img1, ------------(how can I declare cvReCt(10, 15, 150, 250)); //c# IplImage *img2 = cvCreateImage(cvGetSize(img1), img1-depth, img1-nChannels); //c# Image img2; // i supose i needn't to allocate memory.//c# cvCopy(img1, img2, NULL); CvInvoke.cvCopy(img1, img2, IntPtr.Zero);//c# cvResetImageROI(img1); shoul i ResetImageROI.//c# thanx and best regards,

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