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  • Java creation of new set too slow

    - by Mgccl
    I have this program where it have some recursive function similar to this: lambda(HashSet<Integer> s){ for(int i=0;i<w;i++){ HashSet<Integer> p = (HashSet) s.clone(); p.addAll(get_next_set()); lambda(p); } } What I'm doing is union every set with the set s. And run lambda on each one of the union. I run a profiler and found the c.clone() operation took 100% of the time of my code. Are there any way to speed this up considerably?

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  • Postgres : Post statement (or insert) asynchronous, non-blocking processing.

    - by Hassan Syed
    I'm wondering if it is possible, that after a collection of rows is inserted, to initiate an operation that is executed asynchronously, is non-blocking, and doesn't need to inform the originator of the request - of the result. I am working with large amounts of events and I can guarantee that the post-insert logic will not fail -- I just want to have a single insert thread in my event-sources, and I want this thread to keep flying without blocking, and without being responsible for any post-delivery book-keeping. I can tell you that I would potentially have a 100 of these jobs executing concurrently and each job might operate on 5 tables with anywhere between 200-1000 inserts on each of these tables. A hint in the right direction should be enough.

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  • What's the performance penalty of weak_ptr?

    - by Kornel Kisielewicz
    I'm currently designing a object structure for a game, and the most natural organization in my case became a tree. Being a great fan of smart pointers I use shared_ptr's exclusively. However, in this case, the children in the tree will need access to it's parent (example -- beings on map need to be able to access map data -- ergo the data of their parents. The direction of owning is of course that a map owns it's beings, so holds shared pointers to them. To access the map data from within a being we however need a pointer to the parent -- the smart pointer way is to use a reference, ergo a weak_ptr. However, I once read that locking a weak_ptr is a expensive operation -- maybe that's not true anymore -- but considering that the weak_ptr will be locked very often, I'm concerned that this design is doomed with poor performance. Hence the question: What is the performance penalty of locking a weak_ptr? How significant is it?

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  • Where will this AsyncTask run?

    - by Binoy Babu
    Say I have this code in the AlertDialog.Builder(context) of my application. The question is in which Thread will it run? final Thread myPrettyOperation = new Thread() { @Override public void run() { //Do some really long operation. } }; class MyPrettyTask extends AsyncTask<Void, Integer, Boolean> { protected Boolean doInBackground( Void... voids) { myPrettyOperation.start(); return true; } protected void onProgressUpdate( Integer... progress) { } protected void onPostExecute(Boolean result) { } } new MyPrettyTask().execute();

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  • which is better, creating a materialized view or a new table?

    - by Carson
    I have some demanding mysql queries that are needed to grap same up-to-date datasets from 5-7 mysql tables. I am thinking of creating a table or materialized view to gather all demanding columns from other tables, so as to increase performance. If I create that table, I may need to do extra insert / update / delete operation each time other tables updated. if I create materialized view, I am worrying if the performance can be greatly improved. Because data from other tables are changing very frequently. Most likely, the view may need to be created first everytime before selecting it. Any ideas? e.g. how to cache? other extra measures I can do?

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  • How to use a 3rd party control inside the viewmodel?

    - by Sander
    I have a 3rd party control which among other things performs loading of some data. I want my viewmodel to keep track of this load operation and adjust its own state accordingly. If it were up to me, I'd do the data loading far away from the view, but it is not. So, I seem to be in the situation where my viewmodel depends on my view. How do I best handle this? I feel rather dirty making the view publish events to the viewmodel but I don't see any other reasonable way to get this info into the viewmodel. A similar situation might crop up with standard controls, too - imagine if your viewmodel depends on the events coming from a MediaElement - how do you properly model this? Do you put the MediaElement into the viewmodel? That doesn't sound right. If publishing the events to the viewmodel is indeed the most reasonable way, is there some common pattern used for this? How do you do it?

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  • Resetting Objects vs. Constructing New Objects

    - by byronh
    Is it considered better practice and/or more efficient to create a 'reset' function for a particular object that clears/defaults all the necessary member variables to allow for further operations, or to simply construct a new object from outside? I've seen both methods employed a lot, but I can't decide which one is better. Of course, for classes that represent database connections, you'd have to use a reset method rather than constructing a new one resulting in needless connecting/disconnecting, but I'm talking more in terms of abstraction classes. Can anyone give me some real-world examples of when to use each method? In my particular case I'm thinking mostly in terms of ORM or the Model in MVC. For example, if I would want to retrieve a bunch of database objects for display and modify them in one operation.

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  • pass php array to jquery with getJSON

    - by robertdd
    i want to pass a php aray to jQuery: $.getimagesarr = function() { $.getJSON('operations.php', {'operation':'getimglist'}, function(data){ var arr = new Array(); arr = data; return arr; }); } var data = $.getimagesarr(); if (data){ jQuery.each(data, function(i, val) { .... }); } it return undefined in php i have this: function getimglist(){ $results = $_SESSION['files']; echo json_encode($results); } it is possible?

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  • Communicate multiple times with a process without breaking the pipe?

    - by Manux
    Hello, it's not the first time I'm having this problem and its really bugging me. Whenever I open a pipe using the Python subprocess module, I can only communicate with it once, as the documentation specifies: Read data from stdout and stderr, until end-of-file is reached proc = sub.Popen("psql -h darwin -d main_db".split(),stdin=sub.PIPE,stdout=sub.PIPE) print proc.communicate("select a,b,result from experiment_1412;\n")[0] print proc.communicate("select theta,zeta,result from experiment_2099\n")[0] The problem here is that the second time, Python isn't happy. Indeed, he decided to close the file after the first communicate: Traceback (most recent call last): File "a.py", line 30, in <module> print proc.communicate("select theta,zeta,result from experiment_2099\n")[0] File "/usr/lib64/python2.5/subprocess.py", line 667, in communicate return self._communicate(input) File "/usr/lib64/python2.5/subprocess.py", line 1124, in _communicate self.stdin.flush() ValueError: I/O operation on closed file So... multiple communications aren't allowed? I hope not ;) Please enlighten me.

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  • How should I declare default values for instance variables in Python?

    - by int3
    Should I give my class members default values like this: class Foo: num = 1 or like this? class Foo: def __init__(self): self.num = 1 In this question I discovered that in both cases, bar = Foo() bar.num += 1 is a well-defined operation. I understand that the first method will give me a class variable while the second one will not. However, if I do not require a class variable, but only need to set a default value for my instance variables, are both methods equally good? Or one of them more 'pythonic' than the other? One thing I've noticed is that in the Django tutorial, they use the second method to declare Models. Personally I think the second method is more elegant, but I'd like to know what the 'standard' way is.

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  • Repeating a List in Scala

    - by Ralph
    I am a Scala noob. I have decided to write a spider solitaire solver as a first exercise to learn the language and functional programming in general. I would like to generate a randomly shuffled deck of cards containing 1, 2, or 4 suits. Here is what I came up with: val numberOfSuits = 1 (List["clubs", "diamonds", "hearts", "spades"].take(numberOfSuits) * 4).take(4) which should return List["clubs", "clubs", "clubs", "clubs"] List["clubs", "diamonds", "clubs", "diamonds"] List["clubs", "diamonds", "hearts", "spades"] depending on the value of numberOfSuits, except there is no List "multiply" operation that I can find. Did I miss it? Is there a better way to generate the complete deck before shuffling? BTW, I plan on using an Enumeration for the suits, but it was easier to type my question with strings. I will take the List generated above and using a for comprehension, iterate over the suits and a similar List of card "ranks" to generate a complete deck.

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  • Detecting a message box launched in another application

    - by richard-assaf
    I am developing a windows service, in vb .et, that launches a legacy application that performs some work. The service acts as a wrapper around the legacy app allowing users to automate an otherwise manual operation. Everything is working great, except occasionally the legacy app displays a messagebox. When it does this the process halts until the the message box closes. As the service will be running on a server there will be no user to close the message box. The service launches the legacy application in a System.Diagnostics.Process. My question is, is there way to detect that a message box has been displayed by a process that I have started using System.Diagnostics.Process and is there a way to through code to close the messagebox. I've tried to be brief so if you need more information please let me know. Thanks in advance Richie

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  • python: calling constructor from dictionary?

    - by Jason S
    I'm not quite sure of the terminology here so please bear with me.... Let's say I have a constructor call like this: machineSpecificEnvironment = Environment( TI_C28_ROOT = 'C:/appl/ti/ccs/4.1.1/ccsv4/tools/compiler/c2000', JSDB = 'c:/bin/jsdb/jsdb.exe', PYTHON_PATH = 'c:/appl/python/2.6.4', ) except I would like to replace that by an operation on a dictionary provided to me: keys = {'TI_C28_ROOT': 'C:/appl/ti/ccs/4.1.1/ccsv4/tools/compiler/c2000', 'JSDB': 'c:/bin/jsdb/jsdb.exe', 'PYTHON_PATH': 'c:/appl/python/2.6.4'} machineSpecificEnvironment = Environment( ... what do I put here? it needs to be a function of "keys" ... ) How can I do this?

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  • [Cocoa] NSImage transparency

    - by ndg
    I'm trying to set a custom drag icon for use in an NSTableView. Everything seems to work but I've run into a problem due to my inexperience with Quartz. - (NSImage *)dragImageForRowsWithIndexes:(NSIndexSet *)dragRows tableColumns:(NSArray *)tableColumns event:(NSEvent *)dragEvent offset:(NSPointPointer)dragImageOffset { NSImage *dragImage = [NSImage imageNamed:@"icon.png"]; NSString *count = [NSString stringWithFormat:@"%d", [dragRows count]]; [dragImage lockFocus]; [dragImage compositeToPoint:NSZeroPoint fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:0.5]; [count drawAtPoint:NSZeroPoint withAttributes:nil]; [dragImage unlockFocus]; return dragImage; } Essentially what I'm looking to do is render my icon.png file with 50% opacity along with an NSString which shows the number of rows currently being dragged. The issue I'm seeing is that my NSString renders with a low opacity, but not my icon.

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  • Problem with sendkeys in .NET

    - by AvidProgrammer
    I have a windows application, where I am using send keys to navigate from one window to another. My send key sequence is like activating another window with in my app, and sending key strokes to that window. But the key strokes I am sending is getting updated in the same window where I am activating the other window. But after few key strokes it is going to the other window. Seems like synchonization issue with send keys. Is there a way to specify the operation of the current send key is finished, before sending the next sendkey.

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  • Improve performance writing 10 million records to text file using windows service

    - by user1039583
    I'm fetching more than 10 millions of records from database and writing to a text file. It takes hours of time to complete this operation. Is there any option to use TPL features here? It would be great if someone could get me started implementing this with the TPL. using (FileStream fStream = new FileStream("d:\\file.txt", FileMode.OpenOrCreate, FileAccess.ReadWrite)) { BufferedStream bStream = new BufferedStream(fStream); TextWriter writer = new StreamWriter(bStream); for (int i = 0; i < 100000000; i++) { writer.WriteLine(i); } bStream.Flush(); writer.Flush(); // empty buffer; fStream.Flush(); }

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  • What's the proper way to use sqlite on the iPhone?

    - by Elliot Chen
    Hi, Experts: Can you please give some suggestions on sqlite using on the iPhone? Within my application, I use a sqlite DB to store all local data. Two methods can be used to retrieve those data during running time. 1, Load all the data into memory at initialization stage. (More memory used, less DB open/close operation needed) 2, Read corresponding records when necessary, free the occupied memory after using. (Good habit for memory using, but much DB open/close operations needs). I prefer to use method 2, but not sure whether too many DB opening/closing operations could affect app's efficiency. Or do you think I can 'upgrade' method 2 by opening DB when app launches and closing DB when app quits? Thanks for your suggestions very much!

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  • Should class IOException in Java have been an unchecked RuntimeException?

    - by Derek Mahar
    Do you agree that the designers of Java class java.io.IOException should have made it an unchecked run-time exception derived from java.lang.RuntimeException instead of a checked exception derived only from java.lang.Exception? I think that class IOException should have been an unchecked exception because there is little that an application can do to resolve problems like file system errors. However, in When You Can't Throw An Exception, Elliotte Rusty Harold claims that most I/O errors are transient and so you can retry an I/O operation several times before giving up: For instance, an IOComparator might not take an I/O error lying down, but — because many I/O problems are transient — you can retry a few times, as shown in Listing 7: Is this generally the case? Can a Java application correct I/O errors or wait for the system to recover? If so, then it is reasonable for IOException to be checked, but if it is not the case, then IOException should be unchecked so that business logic can delegate handling of this exception to a separate system error handler.

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  • Consuming Third Party web services through Spring WebServiceTemplate

    I'm trying to consume a Third Party web service, through a wsdl file provided. I would load the file locally from a Spring-J2EE based project underneath WEB-INF folder. The wsdl might have more than one operation exposed. So I need a way to be able to choose the method to be called. I would also need to make use of a JaxbMarshaller. Can anyone help with a code snippet for the same? Thanks for the help.

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  • error -4861 - I do a BULK INSERT the contents of a csv file into a table through stored procedure

    - by Chandru
    Hi, Could you please help me,I have an application, in which I do a BULK INSERT the contents of a csv file into a table through stored procedure, the stored Procedure uses BULK INSERT (SQL Server 2005). This Works fine in a standalone system. However when I use the same in a multitier (Web server, Application Server and DB Server) architecture it is throwing 4861 error. Could you please help? The Files are stored in the Web Server. The Translated error message below: " Error – 2147217900:4861: Since it can not be opened for the file \Servername\c$\Folder1\Folder2\Folder3\file.csv, It can not be loaded with large capacity. Operation system error code is 5 (error not ……….) " Thanks Regards, Chandru

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  • problem in multiple asynchronous calls on webservice method in wpf application

    - by black sensei
    Hello Experts! i'm trying to create an application which connects to internet and consume web services for every of it's operation.As far as i'm concerned i'll like to useasync method which i'm using already to get a collection of Contacts.I've realized that when i'm doing the same for groups (meaning getting groups async) i'm having errors in the calls , but when using normal call there ins't.So i did some research online and find that a lot of people has the same problem. Some of them are asked to use WCF (for which i don't know jack).I'll like to know if there is another way to overcome this. if not can somebody point me to reliable resource online and help me get through it? thanks for reading and helping

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  • Using CreateFileMapping between to programs - C

    - by Jamie Keeling
    Hello, I have two window form applications written in C, one holds a struct consisting of two integers, another will receive it using the CreateFileMapping. Although not directly related I want to have three events in place so each of the processes can "speak" to each other, one saying that the first program has something to pass to the second, one saying the first one has closed and another saying the second one has closed. What would be the best way about doing this exactly? I've looked at the MSDN entry for the CreateFileMapping operation but I'm still not sure as to how it should be done. I didn't want to start implementing it without having some sort of clear idea as to what I need to do. Thanks for your time.

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  • Is there a linear-time performance guarantee with using an Iterator?

    - by polygenelubricants
    If all that you're doing is a simple one-pass iteration (i.e. only hasNext() and next(), no remove()), are you guaranteed linear time performance and/or amortized constant cost per operation? Is this specified in the Iterator contract anywhere? Are there data structures/Java Collection which cannot be iterated in linear time? java.util.Scanner implements Iterator<String>. A Scanner is hardly a data structure (e.g. remove() makes absolutely no sense). Is this considered a design blunder? Is something like PrimeGenerator implements Iterator<Integer> considered bad design, or is this exactly what Iterator is for? (hasNext() always returns true, next() computes the next number on demand, remove() makes no sense). Similarly, would it have made sense for java.util.Random implements Iterator<Double>?

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  • How to read a column in a tab-delimited Excel file in C#?

    - by janejanejane
    I have some data of an excel file below. At first, I figured that reading from the file could be done using the Excel Library then using an OLEDB connection. I managed to get the DocumentNo column data with the OLEDB approach. However, when the excel file is closed, I am unable to do the operation because it gives an error that "External table is not in the expected format." How can I read from the file even if it is closed? 10/4/2010 Paid Documents for Document Tracking - Customer 1 Paid Documents for Document Tracking - Customer CoCd Customer Trans.type SG Clearing Clrng doc. Assignment Year DocumentNo Pstng Date Doc. Date Entry Dte Crcy PLDT 5000007 4 4 1/15/2010 25003413 5000007 2010 408000139 1/7/2010 1/5/2010 1/12/2010 PHP PLDT 5000007 4 4 1/15/2010 25003634 5000007 2010 408000068 1/5/2010 12/22/2009 1/10/2010 PHP

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  • How to lowercase every element of a collection efficiently?

    - by Chris
    Whats the most efficient way to lower case every element of a list or set? My idea for a List: final List<String> strings = new ArrayList<String>(); strings.add("HELLO"); strings.add("WORLD"); for(int i=0,l=strings.size();i<l;++i) { strings.add(strings.remove(0).toLowerCase()); } is there a better, faster way? How would this exmaple look like for a set? As there is currently no method for applying an operation to each element of a set (or list) can it be done without creating an additional temporary set? Something like this would be nice: Set<String> strings = new HashSet<String>(); strings.apply( function (element) { this.replace(element, element.toLowerCase();) } ); Thanks,

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