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  • removing duplicate strings from a massive array in java efficiently?

    - by Preator Darmatheon
    I'm considering the best possible way to remove duplicates from an (Unsorted) array of strings - the array contains millions or tens of millions of stringz..The array is already prepopulated so the optimization goal is only on removing dups and not preventing dups from initially populating!! I was thinking along the lines of doing a sort and then binary search to get a log(n) search instead of n (linear) search. This would give me nlogn + n searches which althout is better than an unsorted (n^2) search = but this still seems slow. (Was also considering along the lines of hashing but not sure about the throughput) Please help! Looking for an efficient solution that addresses both speed and memory since there are millions of strings involved without using Collections API!

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  • Piping SoX in Python - subprocess alternative?

    - by Cochise Ruhulessin
    I use SoX in an application. The application uses it to apply various operations on audiofiles, such as trimming. This works fine: from subprocess import Popen, PIPE kwargs = {'stdin': PIPE, 'stdout': PIPE, 'stderr': PIPE} pipe = Popen(['sox','-t','mp3','-', 'test.mp3','trim','0','15'], **kwargs) output, errors = pipe.communicate(input=open('test.mp3','rb').read()) if errors: raise RuntimeError(errors) This will cause problems on large files hower, since read() loads the complete file to memory; which is slow and may cause the pipes' buffer to overflow. A workaround exists: from subprocess import Popen, PIPE import tempfile import uuid import shutil import os kwargs = {'stdin': PIPE, 'stdout': PIPE, 'stderr': PIPE} tmp = os.path.join(tempfile.gettempdir(), uuid.uuid1().hex + '.mp3') pipe = Popen(['sox','test.mp3', tmp,'trim','0','15'], **kwargs) output, errors = pipe.communicate() if errors: raise RuntimeError(errors) shutil.copy2(tmp, 'test.mp3') os.remove(tmp) So the question stands as follows: Are there any alternatives to this approach, aside from writing a Python extension to the Sox C API?

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  • How to return an image in an HTTP response with CherryPy

    - by colinmarc
    I have code which generates a Cairo ImageSurface, and I expose it like so: def preview(...): surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height) ... cherrypy.response.headers['Content-Type'] = "image/png" return surface.get_data() preview.exposed = True This doesn't work (browsers report that the image has errors). I've tested that surface.write_to_png('test.png') works, but I'm not sure what to dump the data into to return it. I'm guessing some file-like object? According to the pycairo documentation, get_data() returns a buffer. I've also now tried: tempf = os.tmpfile() surface.write_to_png(tempf) return tempf Also, is it better to create and hold this image in memory (like I'm trying to do) or write it to disk as a temp file and serve it from there? I only need the image once, then it can be discarded.

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  • How to create a bold and italic label in MFC?

    - by Hamish Grubijan
    Please do not mark it as a dupe of this question just yet: http://stackoverflow.com/questions/1881865/bold-labels-in-mfc That question does not help me; for some reason I do not see the rich edit control. Instead I believe I have to do it in code. here is a sample I found: http://www.tech-archive.net/Archive/VC/microsoft.public.vc.mfc/2006-10/msg00245.html My problem is that I prefer not to re-invent the wheel and test for errors myself or through QA. Someone must have implemented this before. Please share your code. What I would like to do is: Keep the same font size, family, etc. as in the already created label, but make it bold and italic as well. Keep the memory footprint reasonably low (do not create any new unnecessary objects), but do not get the app into an inconsistent state either. I appreciate your help.

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  • Returning an anonymous class that uses a final primitive. How does it work?

    - by Tim P
    Hi, I was wondering if someone could explain how the following code works: public interface Result { public int getCount(); public List<Thing> getThings(); } class SomeClass { ... public Result getThingResult() { final List<Thing> things = .. populated from something. final int count = 5; return new Result { @Override public int getCount() { return count; } @Override public List<Thing> getThings(); return things; } } } ... } Where do the primitive int , List reference and List instance get stored in memory? It can't be on the stack.. so where? Is there a difference between how references and primitives are handled in this situation? Thanks a bunch, Tim P.

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  • Efficiency of checking for null varbinary(max) column ?

    - by Moe Sisko
    Using SQL Server 2008. Example table : CREATE table dbo.blobtest (id int primary key not null, name nvarchar(200) not null, data varbinary(max) null) Example query : select id, name, cast((case when data is null then 0 else 1 end) as bit) as DataExists from dbo.blobtest Now, the query needs to return a "DataExists" column, that returns 0 if the blob is null, else 1. This all works fine, but I'm wondering how efficient it is. i.e. does SQL server need to read in the whole blob to its memory, or is there some optimization so that it just does enough reads to figure out if the blob is null or not ? (FWIW, the sp_tableoption "large value types out of row" option is set to OFF for this example).

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  • Dereferencing pointers without pointing them at a variable

    - by Miguel
    I'm having trouble understanding how some pointers work. I always thought that when you created a pointer variable (p), you couldn't deference and assign (*p = value) unless you either malloc'd space for it (p = malloc(x)), or set it to the address of another variable (p = &a) However in this code, the first assignment works consistently, while the last one causes a segfault: typedef struct { int value; } test_struct; int main(void) { //This works int* colin; *colin = 5; //This never works test_struct* carter; carter->value = 5; } Why does the first one work when colin isn't pointing at any spare memory? And why does the 2nd never work? I'm writing this in C, but people with C++ knowledge should be able to answer this as well.

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  • Proper NSArray initialization for ivar data in a method

    - by Joost Schuur
    I'm new to Objective-C and iPhone development and have been using Apress' Beginning iPhone 3 Programming book as my main guide for a few weeks now. In a few cases as part of a viewDidLoad: method, ivars like a breadTypes NSArray are initialized like below, with an intermediate array defined and then ultimately set to the actual array like this: NSArray *breadArray = [[NSArray alloc] initWithObjects:@"White", @"Whole Weat", @"Rye", @"Sourdough", @"Seven Grain", nil]; self.breadTypes = breadArray; [breadArray release]; Why is it done this way, instead of simply like this: self.breadTypes = [[NSArray alloc] initWithObjects:@"White", @"Whole Weat", @"Rye", @"Sourdough", @"Seven Grain", nil]; Both seem to work when I compile and run it. Is the 2nd method above not doing proper memory management? I assume initWithObjects: returns an array with a retain count of 1 and I eventually release breadTypes again in the dealloc: method, so that wraps things up nicely. I'm guessing 'self.breadTypes = ...' copies the data to the new array, which is why the original array can be safely released, correct?

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  • ActionScript Clean Up

    - by TheDarkIn1978
    i want to deallocate a spriteClass from memory and remove it from the display list. when the spriteClass is instantiated, it creates some of it's own sprites with new tweens and tween events and add them as children. i understand that the tween events must be removed in order for the spritClass to become available for garbage collection, and only afterwards should i nullify the spriteClass, but should i also nullify and remove the spriteClass's sprite children and tweens as well, or does it not matter? essentially i'd like to know if by nullifying the spriteClass it automatically removes all of it's added children and new instantiations like tweens, sprites, rects, whatever, or am i responsible for removing them all and otherwise the spriteClass isn't truly null until i do so?

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  • Launching Vim via Lua

    - by Keith Pimmel
    I'm writing a simple little Lua commandline app that will build a static website. I'm storing my fragments in a sqlite database. Retrieving the data from the db is straightforward as is saving it; my question comes from editing the data. Is there an elegant way to pipe the data from Lua to vim? Can vim edit a memory buffer and return it? I was planning on launching the editor via os.execute('vim') but only after grabbing a temporary file handle and dumping the database output into that. I would like to have to avoid touching the filesystem that way but that is my contingency plan.

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  • Connecting to multiple firebird Databases via Delphi

    - by Branden
    I am integrating a system with 2 other applications, 1 using a Firebird database whilst the other BIS (using ADO). My delphi application uses Firebird. I need to read data from my database, insert it into both the BIS database and the other application firebird database. I have created seperate data modules for each. Sending data to the ADO works fine, but when writing to the other Firebird DB (my db still open) I get strange errors. I have managed to isolate the problem to the second firebird DB. Small data writes seems fine. The data structures are completly different, so un able to use a synch tool. is there a way to overcome this by using multi threading or seperate memory space each Firebird instance uses?

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  • When is a C++ terminate handler the Right Thing(TM)?

    - by Joseph Garvin
    The C++ standard provides the std::set_terminate function which lets you specify what function std::terminate should actually call. std::terminate should only get called in dire circumstances, and sure enough the situations the standard describes for when it's called are dire (e.g. an uncaught exception). When std::terminate does get called the situation seems analagous to being out of memory -- there's not really much you can sensically do. I've read that it can be used to make sure resources are freed -- but for the majority of resources this should be handled automatically by the OS when the process exits (e.g. file handles). Theoretically I can see a case for if say, you needed to send a server a specific message when exiting due to a crash. But the majority of the time the OS handling should be sufficient. When is using a terminate handler the Right Thing(TM)? Update: People interested in what can be done with custom terminate handlers might find this non-portable trick useful.

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  • What do I use when a cron job isn't enough? (php)

    - by mike
    I'm trying to figure out the most efficient way to running a pretty hefty PHP task thousands of times a day. It needs to make an IMAP connection to Gmail, loop over the emails, save this info to the database and save images locally. Running this task every so often using a cron isn't that big of a deal, but I need to run it every minute and I know eventually the crons will start running on top of each other and cause memory issues. What is the next step up when you need to efficiently run a task multiple times a minute? I've been reading about beanstalk & pheanstalk and I'm not entirely sure if that will do what I need. Thoughts???

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  • Recordset manipulation in SSIS

    - by JSacksteder
    In my SSIS job, I have a need to accumulate a set of rows and commit them all transitionally when processing has completed successfully. If this was pure SQL, I would use a temp table inside a transaction. In SSIS there are a number of issues complicating this. It's difficult to have multiple components share the same transaction and having temp tables that do not exist at design time is a pain. If I use Recordsets inside SSIS for this purpose, there are other issues. My understanding is that an 'Execute SQL' component will re-initialize the Recordset when it runs, so I can't use that to append an additional row. Is there a way to create an OLE DB connection that references an in-memory Recordset? Is there a better way to achieve this result?

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  • Delphi - Using DeviceIoControl passing IOCTL_DISK_GET_LENGTH_INFO to get flash media physical size (Not Partition)

    - by SuicideClutchX2
    Alright this is the result of a couple of other questions. It appears I was doing something wrong with the suggestions and at this point have come up with an error when using the suggested API to get the media size. Those new to my problem I am working at the physical disk level, not within the confines of a partition or file system. Here is the pastebin code for the main unit (Delphi 2009) - http://clutchx2.pastebin.com/iMnq8kSx Here is the application source and executable with a form built to output the status of whats going on - http://www.mediafire.com/?js8e6ci8zrjq0de Its probably easier to use the download, unless your just looking for problems within the code. I will also paste the code here. unit Main; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TfrmMain = class(TForm) edtDrive: TEdit; lblDrive: TLabel; btnMethod1: TButton; btnMethod2: TButton; lblSpace: TLabel; edtSpace: TEdit; lblFail: TLabel; edtFail: TEdit; lblError: TLabel; edtError: TEdit; procedure btnMethod1Click(Sender: TObject); private { Private declarations } public { Public declarations } end; TDiskExtent = record DiskNumber: Cardinal; StartingOffset: Int64; ExtentLength: Int64; end; DISK_EXTENT = TDiskExtent; PDiskExtent = ^TDiskExtent; TVolumeDiskExtents = record NumberOfDiskExtents: Cardinal; Extents: array[0..0] of TDiskExtent; end; VOLUME_DISK_EXTENTS = TVolumeDiskExtents; PVolumeDiskExtents = ^TVolumeDiskExtents; var frmMain: TfrmMain; const FILE_DEVICE_DISK = $00000007; METHOD_BUFFERED = 0; FILE_ANY_ACCESS = 0; IOCTL_DISK_BASE = FILE_DEVICE_DISK; IOCTL_VOLUME_BASE = DWORD('V'); IOCTL_DISK_GET_LENGTH_INFO = $80070017; IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS = ((IOCTL_VOLUME_BASE shl 16) or (FILE_ANY_ACCESS shl 14) or (0 shl 2) or METHOD_BUFFERED); implementation {$R *.dfm} function GetLD(Drive: Char): Cardinal; var Buffer : String; begin Buffer := Format('\\.\%s:',[Drive]); Result := CreateFile(PChar(Buffer),GENERIC_READ Or GENERIC_WRITE,FILE_SHARE_READ,nil,OPEN_EXISTING,0,0); If Result = INVALID_HANDLE_VALUE Then begin Result := CreateFile(PChar(Buffer),GENERIC_READ,FILE_SHARE_READ,nil,OPEN_EXISTING,0,0); end; end; function GetPD(Drive: Byte): Cardinal; var Buffer : String; begin If Drive = 0 Then begin Result := INVALID_HANDLE_VALUE; Exit; end; Buffer := Format('\\.\PHYSICALDRIVE%d',[Drive]); Result := CreateFile(PChar(Buffer),GENERIC_READ Or GENERIC_WRITE,FILE_SHARE_READ,nil,OPEN_EXISTING,0,0); If Result = INVALID_HANDLE_VALUE Then begin Result := CreateFile(PChar(Buffer),GENERIC_READ,FILE_SHARE_READ,nil,OPEN_EXISTING,0,0); end; end; function GetPhysicalDiskNumber(Drive: Char): Byte; var LD : DWORD; DiskExtents : PVolumeDiskExtents; DiskExtent : TDiskExtent; BytesReturned : Cardinal; begin Result := 0; LD := GetLD(Drive); If LD = INVALID_HANDLE_VALUE Then Exit; Try DiskExtents := AllocMem(Max_Path); DeviceIOControl(LD,IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS,nil,0,DiskExtents,Max_Path,BytesReturned,nil); If DiskExtents^.NumberOfDiskExtents > 0 Then begin DiskExtent := DiskExtents^.Extents[0]; Result := DiskExtent.DiskNumber; end; Finally CloseHandle(LD); end; end; procedure TfrmMain.btnMethod1Click(Sender: TObject); var PD : DWORD; CardSize: Int64; BytesReturned: DWORD; CallSuccess: Boolean; begin PD := GetPD(GetPhysicalDiskNumber(edtDrive.Text[1])); If PD = INVALID_HANDLE_VALUE Then Begin ShowMessage('Invalid Physical Disk Handle'); Exit; End; CallSuccess := DeviceIoControl(PD, IOCTL_DISK_GET_LENGTH_INFO, nil, 0, @CardSize, SizeOf(CardSize), BytesReturned, nil); if not CallSuccess then begin edtError.Text := IntToStr(GetLastError()); edtFail.Text := 'True'; end else edtFail.Text := 'False'; CloseHandle(PD); end; end. I placed a second method button on the form so I can write a different set of code into the app if I feel like it. Only minimal error handling and safeguards are there is nothing that wasn't necessary for debugging this via source. I tried this on a Sony Memory Stick using a PSP as the reader because I cant find the adapter for using a duo in my machine. The target is an MS and half of my users use a PSP for a reader half dont. However this should work fine on SD cards and that is a secondary target for my work as well. I tried this on a usb memory card reader and several SD cards. Now that I have fixed my attempt I get an error returned. 50 ERROR_NOT_SUPPORTED The request is not supported. I have found an application that uses this API as well as alot of related functions for what I am trying todo. I am getting ready to look into it the application is called DriveImage and its source is here - http://sourceforge.net/projects/diskimage/ The only thing I have really noticed from that application is there use of TFileStream and using that to get a handle on the physical disk.

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  • LINQ to SQL SubmitChangess() progress

    - by Emir
    I'm using LINQ to SQLto import old DBF files into MSSQL. I'm reading all rows and adding them to database using ctx.MyTable.InsertOnSubmit(row) After reading phase is completed I have around 100 000 pending inserts. ctx.SubmitChanges() naturally is taking a long time. Is there any way to track progress of the ctx.submitchanges()? Can ctx.Log somehow be used for this purpose? Update: Is it possible to use ctx.GetChangeSet().Inserts.Count and track insert statements using the Log? Dividing ctx.SubmitChanges() into smaller chunks is not working for me, because I need transaction, all or nothing. Update 2: I've found nice class ActionTextWriter using which I will try to count inserts. http://damieng.com/blog/2008/07/30/linq-to-sql-log-to-debug-window-file-memory-or-multiple-writers

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  • Java: Netbeans debugging session works faster than normal run

    - by Martijn Courteaux
    Hello, I'm making Braid in Netbeans 6.7.1. Computer Spec: Windows 7 Running processes: 46 Running threads: +/- 650 NVidia GeForce 9200M GS Intel Core 2 Duo CPU P8400 @ 2.26Ghz Game-spec with normal run: Memory: between 80 MB and 110 MB CPU: between 9% and 20% CPU when time rewinding: 90% The same values for the debugging session, except when I rewind the time: CPU: 20%. Is there any reason for? Is there a way to reach the same performance with a normal run. This is my repaint code: @Override public void repaint() { BufferStrategy bs = getBufferStrategy(); // numBuffers: 4 Graphics g = bs.getDrawGraphics(); g.setColor(Color.BLACK); g.fillRect(-1, -1, 2000, 2000); gamePanel.paint(g.create(x, y, gameDim.width, gameDim.height)); bs.show(); g.dispose(); Toolkit.getDefaultToolkit().sync(); update(g); } The game runs in fullscreen (undecorated + frame.size = screensize) Martijn

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  • How do sprites work?

    - by Alan
    How do sprites work? I've seen sprites from old school games like Super Mario Brothers, and wondered how they're animated to make a game. They're always presented as one big image map, so how are they used? For Mario (as an example) are there precalculated image co-ordinates that outline mario, and are swapped between various mario sprites to produce animation? Or are sprites pre "cut" during game initialization using precalculated images co-ordinates and stored in memory somewhere? Obviously I know nothing about game development.

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  • SDK for writing DVD's

    - by Matt Warren
    I need to add DVD writing functionality to an application I'm working on. However it needs to be able to write out files that are being grabbed "live" from a camera, over a long period of time. I can't wait until all the files are captured before I start writing them to the DVD, I need to write them out in chunks as I go along. I've looked at IMAPI v2, but the main problems seems to be that you need to point it to all the files you plan to write out to disk before you start the burning process. I know it has to concept of "sessions", which means you can write to the DVD in several parts, before you finally "close" it. But I was wondering if there were any other DVD writing SDK's that allow you to be constantly writing files to a DVD and in particular files that are only in memory. It would be more efficient if I didn't have to write the captured images out to hard before they are burned to DVD. The solution needs to work under .NET on Windows XP and vista

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  • Media Foundation: another way to call IMFActivate::ShutdownObject?

    - by KenC
    Hi, Here is a question about IMFActivate::ActivateObject and IMFActivate::ShutdownObject in Media Foundation. According to MSDN, the component that calls ActivateObject is responsible for calling ShutdownObject. But there are two examples not following this rule: http://msdn.microsoft.com/en-us/library/dd388503%28VS.85%29.aspx and http://msdn.microsoft.com/en-us/library/dd317912%28VS.85%29.aspx In these two examples, they call ActivateObject and then release IMFActivate interface without calling ShutdownObject method. This is going to lead to memory leaking, right? Or there is another way to release the resource occupied by the object? (Can I use IMFMediaSource::Shutdown to release the object instead of using IMFActivate::ShutdownObject) Thanks in advance.

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  • C - Malloc or calloc...and how?

    - by Pedro
    Hi...i have a txt file where the first number define the size of the array's, i know that calloc or malloc can reserve memory, but how? this code: typedef struct alpha{ int *size; char name; int tot; char line[60]; }ALPHA; fgets(line,60,fp); tot=atoi(line); size=(int*)calloc(name,sizeof(int); Imagine that in the first line of the txt is the number 10, wiht this code the size of name will be 10? like name[10]???

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  • Do Blob properties on entities affect query performance?

    - by Jaroslav Záruba
    Hello I'm trying to make my mind on whether to store a binary representation of an entity as its Blob property, or whether I better keep the blobs in some separate 'wrapping' class. Possible impact on memory heap and/or a query execution time are my concerns in the first case, complexity votes against the other one. I know Blobs are not indexed, i.e. index size is not what I'm worrying about. Also I assume for blobs Datastore puts defaultFetchGroup to false, but does it mean that blobs don't make a difference in queries? Regards J. Záruba

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  • Garbage collecting at ColdFusion CFC

    - by Sergii
    Hello. I have a CFC as singletone object in Application scope. One of the methods is used for massive data processing and periodically causes the "Java heap space" errors. EDIT All variables inside the method are VAR-scoped, so they should not be kept in the object scope when invokation ended. It can be a bit dumb question for Java people, but I'd like to know how Java garbage collector cleans up the CFC methods memory: only when whole request ends, or maybe right after each method/function invokation? Second option is interesting because it can allow me to split my large method into the few, as one of the possible optimizations.

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  • Cancel UDP recvfrom in C on Unix

    - by hora
    I'm just starting to learn how network programming in C works, and I've written a small program that sends messages to and from a UNIX terminal. I'm using pthreads in my program, one of which essentially just waits on recvfrom() to receive a message. However, I want to be able to close all threads properly if the users chooses to quit the program. The way I have it set up right now, a different thread just cancels the thread waiting on recvfrom, but I'm worried this might not be a good idea since I'm leaving sockets unclosed and I'm not freeing all the memory I allocated. Is there a way to cancel a recvfrom() call, or some way to run a certain routine upon cancelling a pthread? Thanks.

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  • Optimize code performance when odd/even threads are doing different things in CUDA

    - by Orion Nebula
    Hi all! I have two large vectors, I am trying to do some sort of element multiplication, where an even-numbered element in the first vector is multiplied by the next odd-numbered element in the second vector .... and where the odd-numbered element in the first vector is multiplied by the preceding even-numbered element in the second vector Ex. vector 1 is V1(1) V1(2) V1(3) V1(4) vector 2 is V2(1) V2(2) V2(3) V2(4) V1(1) * V2(2) V1(3) * V2(4) V1(2) * V2(1) V1(4) * V2(3) I have written a Cuda code to do this: (Pds has the elements of the first vector in shared memory, Nds the second Vector) //instead of using %2 .. i check for the first bit to decide if number is odd/even -- faster if ((tx & 0x0001) == 0x0000) Nds[tx+1] = Pds[tx] * Nds[tx+1]; else Nds[tx-1] = Pds[tx] * Nds[tx-1]; __syncthreads(); Is there anyway to further accelerate this code or avoid divergence ? Thanks

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