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Search found 6 results on 1 pages for 'drakosha'.

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• How can i estimate memory usage of stl::map?

  - by Drakosha

  For example, I have a std::map with known sizeof(A) and sizefo(B), while map has N entries inside. How would you estimate its memory usage? I'd say it's something like (sizeof(A) + sizeof(B)) * N * factor But what is the factor? Different formula maybe? Update: Maybe it's easier to ask for upper bound?

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• aio_write on linux with rtkaio is sometimes long

  - by Drakosha

  I'm using async io on linux with rtkaio library. In my tests everything works perfectly, but, in my real application i see that aio_write which is supposed to return very fast, is very slow. It can take more than 100 milis to write a 128KB to a O_DIRECT padded file. Both my test and the application use same I/O size, i check on the same file system (GFS). I added counting and i see that there are about 50% of async io operations that are short (shorter then 2 milis) and 50% that are long (longer than 2 milis). I also checked that the test and the application both use the same rtkaio library. I'm pretty lost, anyone any ideas where should i look? Another my related question: http://stackoverflow.com/questions/1799537/proc-sys-fs-aio-nr-is-never-higher-than-1024-aio-on-linux

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• strange error in haskell about indentation of if-then-else

  - by Drakosha

  I have the following code: foo :: Int -> [String] -> [(FilePath, Integer)] -> IO Int foo _ [] _ = return 4 foo _ _ [] = return 5 foo n nameREs pretendentFilesWithSizes = do result <- (bar n (head nameREs) pretendentFilesWithSizes) if result == 0 then return 0 -- <========================================== here is the error else foo n (tail nameREs) pretendentFilesWithSizes I get an error on the line with the comment above, the error is: aaa.hs:56:2: parse error (possibly incorrect indentation) I'm working with emacs, there's no spaces, and i do not understand what did i do wrong.

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• Can Android applications examine OS wide context, for example network related?

  - by Drakosha

  Can Android applications see OS wide context in terms of network? For example, what applications are using the network what IP addresses is the OS connected to etc. I'm asking because I know each application runs in it's own Dalvik virtual machine.

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• how to raise warning if return value is disregarded - gcc or static code check?

  - by Drakosha

  I'd like to see all the places in my code (C++) which disregard return value of a function. How can I do it - with gcc or static code analysis tool? Bad code example: int f(int z) { return z + (z*2) + z/3 + z*z + 23; } int main() { int i = 7; f(i); ///// <<----- here I disregard the return value return 1; } Update: it should work even if the function and its use are in different files free static check tool

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• dealing with IO vs pure code in haskell

  - by Drakosha

  I'm writing a shell script (my 1st non-example in haskell) which is supposed to list a directory, get every file size, do some string manipulation (pure code) and then rename some files. I'm not sure what i'm doing wrong, so 2 questions: How should i arrange the code in such program? I have a specific issue, i get the following error, what am i doing wrong? error: Couldn't match expected type [FilePath]' against inferred typeIO [FilePath]' In the second argument of mapM', namelyfileNames' In a stmt of a 'do' expression: files <- (mapM getFileNameAndSize fileNames) In the expression: do { fileNames <- getDirectoryContents; files <- (mapM getFileNameAndSize fileNames); sortBy cmpFilesBySize files } code: getFileNameAndSize fname = do (fname, (withFile fname ReadMode hFileSize)) getFilesWithSizes = do fileNames <- getDirectoryContents files <- (mapM getFileNameAndSize fileNames) sortBy cmpFilesBySize files

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