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  • JNI cached jclass global reference variables being garbage collected?

    - by bubbadoughball
    I'm working in the JNI Invocation API, calling into Java from C. I have some upfront initialization to cache 30+ Java classes into global references. The results of FindClass are passed into NewGlobalRef to acquire a global reference to the class. I'm caching these class variables to reuse them later. I have 30+ global references to classes (and 30+ global methodIDs for the class constructors). In the following sample, I've removed exception handling as well as JNI invocation for the purpose of shortening the code snippet. My working code has exception checks after every JNI call and I'm running with -Xcheck:jni. Here's the snippet: jclass aClass; jclass bClass; jmethodID aCtor; jmethodID bCtor; void getGlobalRef(const char* clazz, jclass* globalClass) { jclass local = (*jenv)->FindClass(jenv,clazz); if (local) { *globalClass = (jclass) (*jenv)->NewGlobalRef(jenv,local); (*jenv)->DeleteLocalRef(jenv,local); } } methodID getMethodID(jclass clazz, const char* method, const char* sig) { return (*jenv)->GetMethodID(jenv,clazz,method,sig); } void initializeJNI() { getGlobalRef("MyProj/Testclass1", &aclass); getGlobalRef("MyProj/Testclass2", &bclass); . . aCtor = getMethodID(aclass,"<init>","()V"); bCtor = getMethodID(bclass,"<init>","(I)V"); } The initializeJNI() function sets the global references for jclasses and method IDs for constructors as well as some jfieldID's and some initialization of C data structures. After initialization, when I call into a JNI function using some of the cached jclasses and ctor jmethodIDs, I get a bad global or local reference calling reported from the -Xcheck:jni. In gdb, I break at the last line of initializeJNI(), and print all jclasses and jmethodIDs and the ones causing problems look to have been turned into garbage or garbage-collected (i.e. 0x00 or 0x06). Is it possible for global references to be gc'ed? Any suggestions?

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  • How to check if Thread finished execution

    - by user295502
    I have following problem: I want to check (C#) if thread has finished execution, i.e. if the thread method returned. What I do now is call Thread.Join(1), but this gives 1 ms delay. Is there any way to simply check if thread finished. Inspecting Thread.ThreadState just seems too cumbersome.

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  • Insert data into SQL server with best performance

    - by Incognito
    I have an application which intensively uses DB (SQL Server). As it must have high performance I would like to know the fastest way to insert record into DB.Fastest from the standpoint of execution time. What should I use ? As I know the fastest way is to create stored procedure and to call it from code (ADO.NET). Please let me know is there any better way or may be there are is some other practices to increase performance.

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  • Is it possible to run a Java program inside a Flex application?

    - by Joshua
    I would like to be able to incorporate a simple game, written in Java as a component within a Flex Application. Am I crazy? Flex can display HTML, and SWF, it can also call JavaScript - but can I incorporate an applet somehow? I do NOT mean kludging it in as a sister component within a browser, but actually within the flex application itself, so that it could also run under Adobe Air, for instance.

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  • Multi-Threading Question Concerning WPF

    - by Andrew
    Hello, I'm a newbie to threading, and I don't really know how to code a particular task. I would like to handle a mouse click event on a window that will kick off a while loop in a seperate thread. This thread, which is distinct from the UI thread, should call a function in the while loop which updates a label on the window being serviced by the UI thread. The while loop should stop running when the left mouse button is no longer being pressed. All the loop does is increment a counter, and then repeatedly call the function which displays the updated value in the window. The code for the window and all of the threading is given below (I keep getting some error about STA threading, but don't know where to put the attribute). Also, I'm hoping to use this solution, if it ever works, in another project that makes asynchronous calls elsewhere to a service via wcf, so I was hoping not to make any application-wide special configurations, since I'm really new to multi-threading and am quite worried about breaking other code in a larger program... Here's what I have: <Window x:Class="WpfApplication2.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:WpfApplication2" Name="MyMainWindow" Title="MainWindow" Width="200" Height="150" PreviewMouseLeftButtonDown="MyMainWindow_PreviewMouseLeftButtonDown"> <Label Height="28" Name="CounterLbl" /> </Window> And here's the code-behind: using System.Windows; using System.Windows.Input; using System.Threading; namespace WpfApplication2 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { private int counter = 0; public MainWindow() { InitializeComponent(); } private delegate void EmptyDelegate(); private void MyMainWindow_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) { Thread counterThread = new Thread(new ThreadStart(MyThread)); counterThread.Start(); } private void MyThread() { while (Mouse.LeftButton == MouseButtonState.Pressed) { counter++; Dispatcher.Invoke(new EmptyDelegate(UpdateLabelContents), null); } } private void UpdateLabelContents() { CounterLbl.Content = counter.ToString(); } } } Anyways, multi-threading is really new to me, and I don't have any experience implementing it, so any thoughts or suggestions are welcome! Thanks, Andrew

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  • Some clarification on rvalue references

    - by Dennis Zickefoose
    First: where are std::move and std::forward defined? I know what they do, but I can't find proof that any standard header is required to include them. In gcc44 sometimes std::move is available, and sometimes its not, so a definitive include directive would be useful. When implementing move semantics, the source is presumably left in an undefined state. Should this state necessarily be a valid state for the object? Obviously, you need to be able to call the object's destructor, and be able to assign to it by whatever means the class exposes. But should other operations be valid? I suppose what I'm asking is, if your class guarantees certain invariants, should you strive to enforce those invariants when the user has said they don't care about them anymore? Next: when you don't care about move semantics, are there any limitations that would cause a non-const reference to be preferred over an rvalue reference when dealing with function parameters? void function(T&); over void function(T&&); From a caller's perspective, being able to pass functions temporary values is occasionally useful, so it seems as though one should grant that option whenever it is feasible to do so. And rvalue references are themselves lvalues, so you can't inadvertently call a move-constructor instead of a copy-constructor, or something like that. I don't see a downside, but I'm sure there is one. Which brings me to my final question. You still can not bind temporaries to non-const references. But you can bind them to non-const rvalue references. And you can then pass along that reference as a non-const reference in another function. void function1(int& r) { r++; } void function2(int&& r) { function1(r); } int main() { function1(5); //bad function2(5); //good } Besides the fact that it doesn't do anything, is there anything wrong with that code? My gut says of course not, since changing rvalue references is kind of the whole point to their existence. And if the passed value is legitimately const, the compiler will catch it and yell at you. But by all appearances, this is a runaround of a mechanism that was presumably put in place for a reason, so I'd just like confirmation that I'm not doing anything foolish.

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  • button of MDImenu can't disenable in VS2008

    - by colorlee
    Hi everyone. i had just started to learn VB and VS2008 and im doing some system due to my homework. i made a WELCOME form with a timer, 5s to pass to the next form which called Select. After passed to next form, itll me.visible = false. Theres 3 buttons on the Select form which call Customer, Staff and Exit. As i had just start, the button Customer will pass to a MDI menu call Customer Menu with a menu strip button called Quotation. Same, Select will me.visible = false when done. Then a problem occured, i made a Quotation inside the Customer Menu, such as the mdiparent of Quotation is Customer. I expected that the Quotation button will disenable to press after i pressed that button. But i fail to do that. And the code below: This is the code of MDI menu Customer Menu: Public Class frmCustomer Private Sub ExitToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExitToolStripMenuItem.Click End End Sub Private Sub AboutUsToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles AboutUsToolStripMenuItem.Click Dim frm As New AboutMamatai AboutMamatai.ShowDialog() End Sub Private Sub frmCustomer_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load frmQuotation.MdiParent = Me frmQuotation.Show() frmQuotation.Dock = DockStyle.Fill Me.Location = New Point(220, 180) End Sub Private Sub QuotationToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles QuotationToolStripMenuItem.Click frmQuotation.MdiParent = Me frmQuotation.Show() frmQuotation.Dock = DockStyle.Fill End Sub End Class This is the code of the form inside the Customer menu: Public Class frmQuotation Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click frmCustomer.QuotationToolStripMenuItem.Enabled = True Me.Close() End Sub Private Sub frmQuotation_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load frmCustomer.QuotationToolStripMenuItem.Enabled = False End Sub End Class When im tryin to solve this problem, i found that the problem may cause of the me.visible = false of the Select form and Welcome form. Becoz when i set the Customer Menu be the first form to run. The problem is not exist. Is there anyone can help me ? P.S. I guess if the other two forms code is needed so i post them also This is the code of WELCOME form : Public Class frmWELCOME Private Sub frmWELCOME_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Me.Location = New Point(270, 210) Timer1.Enabled = True End Sub Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick Timer1.Enabled = False Dim frm As New frmSelect frm.Show() Me.Visible = False End Sub Private Sub btnSkip_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSkip.Click Timer1.Enabled = False Dim frm As New frmSelect frm.Show() Me.Visible = False End Sub End Class This is the code of Select Form: Public Class frmSelect Private Sub btnCustomer_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCustomer.Click Dim frm As New frmCustomer frm.Show() Me.Visible = False End Sub Private Sub btnStaff_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStaff.Click Dim frm As New frmStaff frm.Show() Me.Visible = False End Sub Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click End End Sub Private Sub frmSelect_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Me.Location = New Point(390, 250) End Sub End Class

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  • Is there an automatic way to generate a rollback script when inserting data with LINQ2SQL?

    - by Jedidja
    Let's assume we have a bunch of LINQ2SQL InsertOnSubmit statements against a given DataContext. If the SubmitChanges call is successful, is there any way to automatically generate a list of SQL commands (or even LINQ2SQL statements) that would automatically undo everything that was submitted? It's like executing a rollback even though everything worked as expected. Note: The destination database will either be Oracle or SQL Server, so if there is specific functionality for both databases that will achieve this, I'm happy to use that as well.

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  • beneficial in terms of performance

    - by Usama Khalil
    Hi, is it better to declare Webservice class object instances as static as the .asmx webservice classes have only static methods. what i want is that i declare and instantiate webservice asmx class as static in aspx Page Behind Class. and on every event call on that page i could perform operation against webservice methods. is it beneficial in terms of performance? Thanks Usama

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  • How to add string to jQuery selector?

    - by Deshiknaves
    I'm trying to select an id that changes on different posts of same page. So the they have been given an id="show_posts_{PostID}" - on the final output the {PostID} is replaced with a number. In the function I need to call $('show_posts_XXXXXX') - XXXXXX being the generated ID. I have stored this ID in a variable called postId. But I can't seem to do this $("'" + "show_posts_" + postId + "'") Can anyone tell me how I can add a string to the end of a selector?

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  • Calling a function within a class

    - by JM4
    I am having trouble calling a specific function within a class. The call is made: case "Mod10": if (!validateCreditCard($fields[$field_name])) $errors[] = $error_message; break; and the class code is: class CreditCardValidationSolution { var $CCVSNumber = ''; var $CCVSNumberLeft = ''; var $CCVSNumberRight = ''; var $CCVSType = ''; var $CCVSError = ''; function validateCreditCard($Number) { $this->CCVSNumber = ''; $this->CCVSNumberLeft = ''; $this->CCVSNumberRight = ''; $this->CCVSType = ''; $this->CCVSError = ''; // Catch malformed input. if (empty($Number) || !is_string($Number)) { $this->CCVSError = $CCVSErrNumberString; return FALSE; } // Ensure number doesn't overrun. $Number = substr($Number, 0, 20); // Remove non-numeric characters. $this->CCVSNumber = preg_replace('/[^0-9]/', '', $Number); // Set up variables. $this->CCVSNumberLeft = substr($this->CCVSNumber, 0, 4); $this->CCVSNumberRight = substr($this->CCVSNumber, -4); $NumberLength = strlen($this->CCVSNumber); $DoChecksum = 'Y'; // Mod10 checksum process... if ($DoChecksum == 'Y') { $Checksum = 0; // Add even digits in even length strings or odd digits in odd length strings. for ($Location = 1 - ($NumberLength % 2); $Location < $NumberLength; $Location += 2) { $Checksum += substr($this->CCVSNumber, $Location, 1); } // Analyze odd digits in even length strings or even digits in odd length strings. for ($Location = ($NumberLength % 2); $Location < $NumberLength; $Location += 2) { $Digit = substr($this->CCVSNumber, $Location, 1) * 2; if ($Digit < 10) { $Checksum += $Digit; } else { $Checksum += $Digit - 9; } } // Checksums not divisible by 10 are bad. if ($Checksum % 10 != 0) { $this->CCVSError = $CCVSErrChecksum; return FALSE; } } return TRUE; } } When I run the application - I get the following message: Fatal error: Call to undefined function validateCreditCard() in C:\xampp\htdocs\validation.php on line 339 any ideas?

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  • android: handover sms to default application

    - by harisali
    HI Plz guide, In android how can i pass my string (less then 160 char) to default builtin sms applicaion or queue, who must do rest of process. I meant, from my activity i want to call buitin sms application, & pass my sms string to that , then builtin application will be responsible to rest of activity like sms sent retry, ???

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  • Two Phase Commit with MongoDB

    - by mattcodes
    Heres what Im thinking. Do you see any issues with this workaround to emulate 2 phase commit when using something like MongoDB where each operation is atomic and there is no support for transactions outside of that? transaction_scope: read message from servicebus - UpdateCustomerAddress get customer aggregate from docdb, replay events where commited =1 call customer.updateAddress validates creates customer address updated event apply event event store as uncommitted events do optimistic concurrency update against docdb pushing uncommitted events (single op to ensure consistency) publish event to service bus update docdb set events just published to commited = 1 (again one 1 op - at least in mongodb) transaction_complete

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  • Share ASP.Net membership info between two applications

    - by bill
    Hi All, I have an existing webapp and i'm attempting to setup BlogEngine .Net to share the membership tables Everything seems to work.. accept i can see that the Membership.ValidateUser call in blogengine returns false! While the other apps returns true. I'm at a loss.. Membership.GetUser called from both apps returns the correct user.. Any ideas? thanks!

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  • Difference between Python urllib.urlretrieve() and wget

    - by jrdioko
    I am trying to retrieve a 500mb file using Python, and I have a script which uses urllib.urlretrieve(). There seems to some network problem between me and the download site, as this call consistently hangs and fails to complete. However, using wget to retrieve the file tends to work without problems. What is the difference between urlretrieve() and wget that could cause this difference?

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  • Spring, iBatis, MySQL - how to manage transactions?

    - by Enrique
    Hello I'm building a web application with spring ibatis and mysql. I'm going to use mysql stored procedures and I will call them with ibatis. My question is about how to manage the transactions. Should I manage the transactions inside the stored procedures or with spring/ibatis or with both?

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  • Implementing Skip List in C++

    - by trikker
    [SOLVED] So I decided to try and create a sorted doubly linked skip list... I'm pretty sure I have a good grasp of how it works. When you insert x the program searches the base list for the appropriate place to put x (since it is sorted), (conceptually) flips a coin, and if the "coin" lands on a then that element is added to the list above it(or a new list is created with element in it), linked to the element below it, and the coin is flipped again, etc. If the "coin" lands on b at anytime then the insertion is over. You must also have a -infinite stored in every list as the starting point so that it isn't possible to insert a value that is less than the starting point (meaning that it could never be found.) To search for x, you start at the "top-left" (highest list lowest value) and "move right" to the next element. If the value is less than x than you continue to the next element, etc. until you have "gone too far" and the value is greater than x. In this case you go back to the last element and move down a level, continuing this chain until you either find x or x is never found. To delete x you simply search x and delete it every time it comes up in the lists. For now, I'm simply going to make a skip list that stores numbers. I don't think there is anything in the STL that can assist me, so I will need to create a class List that holds an integer value and has member functions, search, delete, and insert. The problem I'm having is dealing with links. I'm pretty sure I could create a class to handle the "horizontal" links with a pointer to the previous element and the element in front, but I'm not sure how to deal with the "vertical" links (point to corresponding element in other list?) If any of my logic is flawed please tell me, but my main questions are: How to deal with vertical links and whether my link idea is correct Now that I read my class List idea I'm thinking that a List should hold a vector of integers rather than a single integer. In fact I'm pretty positive, but would just like some validation. I'm assuming the coin flip would simply call int function where rand()%2 returns a value of 0 or 1 and if it's 0 then a the value "levels up" and if it's 0 then the insert is over. Is this incorrect? How to store a value similar to -infinite? Edit: I've started writing some code and am considering how to handle the List constructor....I'm guessing that on its construction, the "-infinite" value should be stored in the vectorname[0] element and I can just call insert on it after its creation to put the x in the appropriate place.

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  • Quick question regarding this issue, Why doesnt it print out the second value(converted second value

    - by sil3nt
    Quick question, What have I done wrong here. The purpose of this code is to get the input into a string, the input being "12 34", with a space in between the "12" and "32" and to convert and print the two separate numbers from an integer variable known as number. Why doesn't the second call to the function copyTemp, not produce the value 34?. I have an index_counter variable which keeps track of the string index and its meant to skip the 'space' character?? what have i done wrong? thanks. #include <stdio.h> #include <string.h> int index_counter = 0; int number; void copyTemp(char *expr,char *temp); int main(){ char exprstn[80]; //as global? char tempstr[80]; gets(exprstn); copyTemp(exprstn,tempstr); printf("Expression: %s\n",exprstn); printf("Temporary: %s\n",tempstr); printf("number is: %d\n",number); copyTemp(exprstn,tempstr); //second call produces same output shouldnt it now produce 34 in the variable number? printf("Expression: %s\n",exprstn); printf("Temporary: %s\n",tempstr); printf("number is: %d\n",number); return 0; } void copyTemp(char *expr,char *temp){ int i; for(i = index_counter; expr[i] != '\0'; i++){ if (expr[i] == '0'){ temp[i] = expr[i]; } if (expr[i] == '1'){ temp[i] = expr[i]; } if (expr[i] == '2'){ temp[i] = expr[i]; } if (expr[i] == '3'){ temp[i] = expr[i]; } if (expr[i] == '4'){ temp[i] = expr[i]; } if (expr[i] == '5'){ temp[i] = expr[i]; } if (expr[i] == '6'){ temp[i] = expr[i]; } if (expr[i] == '7'){ temp[i] = expr[i]; } if (expr[i] == '8'){ temp[i] = expr[i]; } if (expr[i] == '9'){ temp[i] = expr[i]; } if (expr[i] == ' '){ temp[i] = '\0'; sscanf(temp,"%d",&number); index_counter = i+1; //skips? } } // is this included here? temp[i] = '\0'; }

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  • How does a GUI Framework work?

    - by AlexW.H.B.
    I have been all over the web looking for an answer to this, and my question is this: How does a GUI framework work? for instance how does Qt work, is there any books or wibsites on the topic of writing a GUI framework from scratch? and also does the framework have to call methods from the operating systems GUI framework? -- Thank you to any one who takes the time to try to answer this question, and forgive me if i misspelled anything.

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