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  • Updatable false behvior incosistent

    - by jpanewbie
    I need LastUpdatedDttm to be updated by SYSDATE whenever record is updated. But below annoataions do nt work as desired. SYSDATE is inserted only once and not updated for subsequent updations. Also, lastUpdDTTM is not part of sql generated by hibernate. @Generated(GenerationTime.ALWAYS) @Column(name="LAST_UPDATED_DTTM",insertable=false,updatable=true, columnDefinition ="timestamp default SYSDATE") private Date lastUpdDTTM; @Generated(GenerationTime.ALWAYS) @Column(name="CREATED_DTTM", insertable=false, updatable=false) private Date createdDTTM;

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  • Android OnClick in ListView calling parent function

    - by user1321683
    I have an Android application with a ListView in it, the ListView will setup fine but now I want a image in the ListView to be clickable. I do this by using 2 classes, the Activity class (parent) and an ArrayAdapter to fill the list. In the ArrayAdapter I implement a OnClickListener for the image in the list that I want to be clickable. So far it all works. But now I want to run a function from the activity class when the onClick, for the image in the list, is run but I do not know how. Below are the 2 classes that I use. First the Activity class: public class parent_class extends Activity implements OnClickListener, OnItemClickListener { child_class_list myList; ListView myListView; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); // setup the Homelist data myList = new child_class_list (this, Group_Names, Group_Dates); myListView = (ListView) findViewById(R.id.list); // set the HomeList myListView.setAdapter( myList ); myListView.setOnItemClickListener(this); } void function_to_run() { // I want to run this function from the LiscView Onclick } public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // do something } } And the ArrayAdapter from where I want to call a function from the Activity class: public class child_class_list extends ArrayAdapter<String> { // private private final Context context; private String[] mName; private String[] mDate; public child_class_list (Context context, String[] Name, String[] Date) { super(context, R.layout.l_home, GroupName); this.context = context; this.mName = Name; this.mDate = Date; } @Override public View getView(int position, View convertView, ViewGroup parent) { LayoutInflater inflater = (LayoutInflater) context .getSystemService(Context.LAYOUT_INFLATER_SERVICE); View rowView = inflater.inflate(R.layout.l_home, parent, false); ImageView selectable_image = (ImageView) rowView.findViewById(R.id.l_selectable_image); selectable_image.setOnClickListener(new OnClickListener() { public void onClick(View v) { // I want to run the function_to_run() function from the parant class here } } ); // get the textID's TextView tvName = (TextView) rowView.findViewById(R.id.l_name); TextView tvDate = (TextView) rowView.findViewById(R.id.l_date); // set the text tvName.setText (mName[position]); tvDate.setText (mDate[position]); return rowView; } } If anyone knows how to run the function in the activity class from the arrayadapter or how to set the image onClickListener in the Activity Class I would greatly apriciate the help.

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  • drag to pan on an UserControl

    - by Matías
    Hello, I'm trying to build my own "PictureBox like" control adding some functionalities. For example, I want to be able to pan over a big image by simply clicking and dragging with the mouse. The problem seems to be on my OnMouseMove method. If I use the following code I get the drag speed and precision I want, but of course, when I release the mouse button and try to drag again the image is restored to its original position. using System.Drawing; using System.Windows.Forms; namespace Testing { public partial class ScrollablePictureBox : UserControl { private Image image; private bool centerImage; public Image Image { get { return image; } set { image = value; Invalidate(); } } public bool CenterImage { get { return centerImage; } set { centerImage = value; Invalidate(); } } public ScrollablePictureBox() { InitializeComponent(); SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer, true); Image = null; AutoScroll = true; AutoScrollMinSize = new Size(0, 0); } private Point clickPosition; private Point scrollPosition; protected override void OnMouseDown(MouseEventArgs e) { base.OnMouseDown(e); clickPosition.X = e.X; clickPosition.Y = e.Y; } protected override void OnMouseMove(MouseEventArgs e) { base.OnMouseMove(e); if (e.Button == MouseButtons.Left) { scrollPosition.X = clickPosition.X - e.X; scrollPosition.Y = clickPosition.Y - e.Y; AutoScrollPosition = scrollPosition; } } protected override void OnPaint(PaintEventArgs e) { base.OnPaint(e); e.Graphics.FillRectangle(new Pen(BackColor).Brush, 0, 0, e.ClipRectangle.Width, e.ClipRectangle.Height); if (Image == null) return; int centeredX = AutoScrollPosition.X; int centeredY = AutoScrollPosition.Y; if (CenterImage) { //Something not relevant } AutoScrollMinSize = new Size(Image.Width, Image.Height); e.Graphics.DrawImage(Image, new RectangleF(centeredX, centeredY, Image.Width, Image.Height)); } } } But if I modify my OnMouseMove method to look like this: protected override void OnMouseMove(MouseEventArgs e) { base.OnMouseMove(e); if (e.Button == MouseButtons.Left) { scrollPosition.X += clickPosition.X - e.X; scrollPosition.Y += clickPosition.Y - e.Y; AutoScrollPosition = scrollPosition; } } ... you will see that the dragging is not smooth as before, and sometimes behaves weird (like with lag or something). What am I doing wrong? I've also tried removing all "base" calls on a desperate movement to solve this issue, haha, but again, it didn't work. Thanks for your time.

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  • Synchronizing thread communication?

    - by Roger Alsing
    Just for the heck of it I'm trying to emulate how JRuby generators work using threads in C#. Also, I'm fully aware that C# haas built in support for yield return, I'm just toying around a bit. I guess it's some sort of poor mans coroutines by keeping multiple callstacks alive using threads. (even though none of the callstacks should execute at the same time) The idea is like this: The consumer thread requests a value The worker thread provides a value and yields back to the consumer thread Repeat untill worker thread is done So, what would be the correct way of doing the following? //example class Program { static void Main(string[] args) { ThreadedEnumerator<string> enumerator = new ThreadedEnumerator<string>(); enumerator.Init(() => { for (int i = 1; i < 100; i++) { enumerator.Yield(i.ToString()); } }); foreach (var item in enumerator) { Console.WriteLine(item); }; Console.ReadLine(); } } //naive threaded enumerator public class ThreadedEnumerator<T> : IEnumerator<T>, IEnumerable<T> { private Thread enumeratorThread; private T current; private bool hasMore = true; private bool isStarted = false; AutoResetEvent enumeratorEvent = new AutoResetEvent(false); AutoResetEvent consumerEvent = new AutoResetEvent(false); public void Yield(T item) { //wait for consumer to request a value consumerEvent.WaitOne(); //assign the value current = item; //signal that we have yielded the requested enumeratorEvent.Set(); } public void Init(Action userAction) { Action WrappedAction = () => { userAction(); consumerEvent.WaitOne(); enumeratorEvent.Set(); hasMore = false; }; ThreadStart ts = new ThreadStart(WrappedAction); enumeratorThread = new Thread(ts); enumeratorThread.IsBackground = true; isStarted = false; } public T Current { get { return current; } } public void Dispose() { enumeratorThread.Abort(); } object System.Collections.IEnumerator.Current { get { return Current; } } public bool MoveNext() { if (!isStarted) { isStarted = true; enumeratorThread.Start(); } //signal that we are ready to receive a value consumerEvent.Set(); //wait for the enumerator to yield enumeratorEvent.WaitOne(); return hasMore; } public void Reset() { throw new NotImplementedException(); } public IEnumerator<T> GetEnumerator() { return this; } System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return this; } } Ideas?

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  • .htaccess - proxy AND browser caching???

    - by StackOverflowNewbie
    In .htaccess, how do I specify a file type to be cached via browser and proxy? Cache-control for needs to be "private" for browser, "public" for proxy. However, I can't define Cache-Control to be private AND public for same file type. It seems like I have to choose between browser or proxy caching. Suggestions?

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  • How to change method signature in Netbeans Form Editor?

    - by Dzmitry Zhaleznichenka
    I create GUI in Netbeans Form Editor and want to change an auto-generated signature of one method, namely to add throws to it. How to do it? For instance, I have private void btOpenFileActionPerformed(java.awt.event.ActionEvent evt) {} And want to make it private void btOpenFileActionPerformed(java.awt.event.ActionEvent evt) throws AssertionError{} As the method signature is auto-generated, I cannot change it manually.

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  • Should we denormalize database to improve performance?

    - by Groo
    We have a requirement to store 500 measurements per second, coming from several devices. Each measurement consists of a timestamp, a quantity type, and several vector values. Right now there is 8 vector values per measurement, and we may consider this number to be constant for needs of our prototype project. We are using HNibernate. Tests are done in SQLite (disk file db, not in-memory), but production will probably be MsSQL. Our Measurement entity class is the one that holds a single measurement, and looks like this: public class Measurement { public virtual Guid Id { get; private set; } public virtual Device Device { get; private set; } public virtual Timestamp Timestamp { get; private set; } public virtual IList<VectorValue> Vectors { get; private set; } } Vector values are stored in a separate table, so that each of them references its parent measurement through a foreign key. We have done a couple of things to ensure that generated SQL is (reasonably) efficient: we are using Guid.Comb for generating IDs, we are flushing around 500 items in a single transaction, ADO.Net batch size is set to 100 (I think SQLIte does not support batch updates? But it might be useful later). The problem Right now we can insert 150-200 measurements per second (which is not fast enough, although this is SQLite we are talking about). Looking at the generated SQL, we can see that in a single transaction we insert (as expected): 1 timestamp 1 measurement 8 vector values which means that we are actually doing 10x more single table inserts: 1500-2000 per second. If we placed everything (all 8 vector values and the timestamp) into the measurement table (adding 9 dedicated columns), it seems that we could increase our insert speed up to 10 times. Switching to SQL server will improve performance, but we would like to know if there might be a way to avoid unnecessary performance costs related to the way database is organized right now. [Edit] With in-memory SQLite I get around 350 items/sec (3500 single table inserts), which I believe is about as good as it gets with NHibernate (taking this post for reference: http://ayende.com/Blog/archive/2009/08/22/nhibernate-perf-tricks.aspx). But I might as well switch to SQL server and stop assuming things, right? I will update my post as soon as I test it.

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  • Django - I got TemplateSyntaxError when I try open the admin page. (http://DOMAIN_NAME/admin)

    - by user140827
    I use grappelly plugin. When I try open the admin page (/admin) I got TemplateSyntaxError. It says 'get_generic_relation_list' is invalid block tag. TemplateSyntaxError at /admin/ Invalid block tag: 'get_generic_relation_list', expected 'endblock' Request Method: GET Request URL: http://DOMAIN_NAME/admin/ Django Version: 1.4 Exception Type: TemplateSyntaxError Exception Value: Invalid block tag: 'get_generic_relation_list', expected 'endblock' Exception Location: /opt/python27/django/1.4/lib/python2.7/site-packages/django/template/base.py in invalid_block_tag, line 320 Python Executable: /opt/python27/django/1.4/bin/python Python Version: 2.7.0 Python Path: ['/home/vhosts/DOMAIN_NAME/httpdocs/media', '/home/vhosts/DOMAIN_NAME/private/new_malinnikov/lib', '/home/vhosts/DOMAIN_NAME/httpdocs/', '/home/vhosts/DOMAIN_NAME/private/new_malinnikov', '/home/vhosts/DOMAIN_NAME/private/new_malinnikov', '/home/vhosts/DOMAIN_NAME/private', '/opt/python27/django/1.4', '/home/vhosts/DOMAIN_NAME/httpdocs', '/opt/python27/django/1.4/lib/python2.7/site-packages/setuptools-0.6c12dev_r88846-py2.7.egg', '/opt/python27/django/1.4/lib/python2.7/site-packages/pip-0.8.1-py2.7.egg', '/opt/python27/django/1.4/lib/python27.zip', '/opt/python27/django/1.4/lib/python2.7', '/opt/python27/django/1.4/lib/python2.7/plat-linux2', '/opt/python27/django/1.4/lib/python2.7/lib-tk', '/opt/python27/django/1.4/lib/python2.7/lib-old', '/opt/python27/django/1.4/lib/python2.7/lib-dynload', '/opt/python27/lib/python2.7', '/opt/python27/lib/python2.7/plat-linux2', '/opt/python27/lib/python2.7/lib-tk', '/opt/python27/django/1.4/lib/python2.7/site-packages', '/opt/python27/lib/python2.7/site-packages/setuptools-0.6c11-py2.7.egg', '/opt/python27/lib/python2.7/site-packages/flup-1.0.3.dev_20100525-py2.7.egg', '/opt/python27/lib/python2.7/site-packages/virtualenv-1.5.1-py2.7.egg', '/opt/python27/lib/python2.7/site-packages/SQLAlchemy-0.6.4-py2.7.egg', '/opt/python27/lib/python2.7/site-packages/SQLObject-0.14.1-py2.7.egg', '/opt/python27/lib/python2.7/site-packages/FormEncode-1.2.3dev-py2.7.egg', '/opt/python27/lib/python2.7/site-packages/MySQL_python-1.2.3-py2.7-linux-x86_64.egg', '/opt/python27/lib/python2.7/site-packages/psycopg2-2.2.2-py2.7-linux-x86_64.egg', '/opt/python27/lib/python2.7/site-packages/pysqlite-2.6.0-py2.7-linux-x86_64.egg', '/opt/python27/lib/python2.7/site-packages', '/opt/python27/lib/python2.7/site-packages/PIL'] Server time: ???, 7 ??? 2012 04:19:42 +0700 Error during template rendering In template /home/vhosts/DOMAIN_NAME/httpdocs/templates/grappelli/admin/base.html, error at line 28 Invalid block tag: 'get_generic_relation_list', expected 'endblock' 18 <!--[if lt IE 8]> 19 <script src="http://ie7-js.googlecode.com/svn/version/2.0(beta3)/IE8.js" type="text/javascript"></script> 20 <![endif]--> 21 {% block javascripts %} 22 <script type="text/javascript" src="{% admin_media_prefix %}jquery/jquery-1.3.2.min.js"></script> 23 <script type="text/javascript" src="{% admin_media_prefix %}js/admin/Bookmarks.js"></script> 24 <script type="text/javascript"> 25 // Admin URL 26 var ADMIN_URL = "{% get_admin_url %}"; 27 // Generic Relations 28 {% get_generic_relation_list %} 29 // Get Bookmarks 30 $(document).ready(function(){ 31 $.ajax({ 32 type: "GET", 33 url: '{% url grp_bookmark_get %}', 34 data: "path=" + escape(window.location.pathname + window.location.search), 35 dataType: "html", 36 success: function(data){ 37 $('ul#bookmarks').replaceWith(data); 38 }

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  • static readonly field initializer vs static constructor initialization

    - by stackoverflowuser
    Below are 2 different ways to initialize static readonly fields. Is there a difference between the 2 approaches? If yes, when should one be preferred over the other? class A { private static readonly string connectionString = WebConfigurationManager.ConnectionStrings["SomeConnection"].ConnectionString; } class B { private static readonly string connectionString; static B() { connectionString = WebConfigurationManager.ConnectionStrings["SomeConnection"].ConnectionString; } } Thanks.

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  • TextBox and Thread

    - by gloris
    Why doesn't this work? The program stops on: this.textBox1.Text = "(New text)"; Thread demoThread; private void Form1_Load(object sender, EventArgs e) { this.demoThread = new Thread(new ThreadStart(this.ThreadProcUnsafe)); this.demoThread.Start(); textBox1.Text = "Written by the main thread."; } private void ThreadProcUnsafe() { while (true) { Thread.Sleep(2000); this.textBox1.Text = "(New text)"; } }

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  • readObject() vs. readResolve() to restore transient fields

    - by Joonas Pulakka
    According to Serializable javadoc, readResolve() is intended for replacing an object read from the stream. But is it OK to use it for restoring transient fields, like so: private Object readResolve() { transientField = something; return this; } as opposed to using readObject(): private void readObject(ObjectInputStream s) { s.defaultReadObject(); transientField = something; } Is there any reason to choose one over other, when used to just restore transient fields?

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  • Scala: is it possible to override default case class constructor?

    - by adam77
    Just wondering if this is possible. What I would actually like to do is check and possibly modify one of the arguments before it is stored as a val. Alternatively, I could use an overload and make the default constructor private. In which case I would also like to make private the default factory constructor in the companion object, how would I do that? Many thanks. Adam

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  • Dijkstras Algorithm exaplination java

    - by alchemey89
    Hi, I have found an implementation for dijkstras algorithm on the internet and was wondering if someone could help me understand how the code works. Many thanks private int nr_points=0; private int[][]Cost; private int []mask; private void dijkstraTSP() { if(nr_points==0)return; //algorithm=new String("Dijkstra"); nod1=new Vector(); nod2=new Vector(); weight=new Vector(); mask=new int[nr_points]; //initialise mask with zeros (mask[x]=1 means the vertex is marked as used) for(int i=0;i<nr_points;i++)mask[i]=0; //Dijkstra: int []dd=new int[nr_points]; int []pre=new int[nr_points]; int []path=new int[nr_points+1]; int init_vert=0,pos_in_path=0,new_vert=0; //initialise the vectors for(int i=0;i<nr_points;i++) { dd[i]=Cost[init_vert][i]; pre[i]=init_vert; path[i]=-1; } pre[init_vert]=0; path[0]=init_vert; pos_in_path++; mask[init_vert]=1; for(int k=0;k<nr_points-1;k++) { //find min. cost in dd for(int j=0;j<nr_points;j++) if(dd[j]!=0 && mask[j]==0){new_vert=j; break;} for(int j=0;j<nr_points;j++) if(dd[j]<dd[new_vert] && mask[j]==0 && dd[j]!=0)new_vert=j; mask[new_vert]=1; path[pos_in_path]=new_vert; pos_in_path++; for(int j=0;j<nr_points;j++) { if(mask[j]==0) { if(dd[j]>dd[new_vert]+Cost[new_vert][j]) { dd[j]=dd[new_vert]+Cost[new_vert][j]; } } } } //Close the cycle path[nr_points]=init_vert; //Save the solution in 3 vectors (for graphical purposes) for(int i=0;i<nr_points;i++) { nod1.addElement(path[i]); nod2.addElement(path[i+1]); weight.addElement(Cost[path[i]][path[i+1]]); } }

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  • Understanding Ruby class vs instance methods

    - by randombits
    I have the following code: #!/usr/bin/ruby class Person def self.speak p = self.new puts "Hello" p.chatter end private def chatter puts "Chattering" end end p = Person.new Person.speak I'd like to make chatter private, accessible only within p.. but I want p to be able to access it within the class method. Is there a better way to design this so chatter isn't available to the public, but a "factory" method like self.speak can call chatter?

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  • Unselecting RadioButtons in Java Swing

    - by Thomas
    When displaying a group of JRadioButtons, initially none of them is selected (unless you programmatically enforce that). I would like to be able to put buttons back into that state even after the user already selected one, i.e., none of the buttons should be selected. However, using the usual suspects doesn't deliver the required effect: calling 'setSelected(false)' on each button doesn't work. Interestingly, it does work when the buttons are not put into a ButtonGroup - unfortunately, the latter is required for JRadioButtons to be mutually exclusive. Also, using the setSelected(ButtonModel, boolean) - method of javax.swing.ButtonGroup doesn't do what I want. I've put together a small program to demonstrate the effect: two radio buttons and a JButton. Clicking the JButton should unselect the radio buttons so that the window looks exactly as it does when it first pops up. import java.awt.Container; import java.awt.GridLayout; import java.awt.event.*; import javax.swing.*; /** * This class creates two radio buttons and a JButton. Initially, none * of the radio buttons is selected. Clicking on the JButton should * always return the radio buttons into that initial state, i.e., * should disable both radio buttons. */ public class RadioTest implements ActionListener { /* create two radio buttons and a group */ private JRadioButton button1 = new JRadioButton("button1"); private JRadioButton button2 = new JRadioButton("button2"); private ButtonGroup group = new ButtonGroup(); /* clicking this button should unselect both button1 and button2 */ private JButton unselectRadio = new JButton("Unselect radio buttons."); /* In the constructor, set up the group and event listening */ public RadioTest() { /* put the radio buttons in a group so they become mutually * exclusive -- without this, unselecting actually works! */ group.add(button1); group.add(button2); /* listen to clicks on 'unselectRadio' button */ unselectRadio.addActionListener(this); } /* called when 'unselectRadio' is clicked */ public void actionPerformed(ActionEvent e) { /* variant1: disable both buttons directly. * ...doesn't work */ button1.setSelected(false); button2.setSelected(false); /* variant2: disable the selection via the button group. * ...doesn't work either */ group.setSelected(group.getSelection(), false); } /* Test: create a JFrame which displays the two radio buttons and * the unselect-button */ public static void main(String[] args) { JFrame frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); RadioTest test = new RadioTest(); Container contentPane = frame.getContentPane(); contentPane.setLayout(new GridLayout(3,1)); contentPane.add(test.button1); contentPane.add(test.button2); contentPane.add(test.unselectRadio); frame.setSize(400, 400); frame.setVisible(true); } } Any ideas anyone? Thanks!

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  • How to define generic super type for static factory method?

    - by Esko
    If this has already been asked, please link and close this one. I'm currently prototyping a design for a simplified API of a certain another API that's a lot more complex (and potentially dangerous) to use. Considering the related somewhat complex object creation I decided to use static factory methods to simplify the API and I currently have the following which works as expected: public class Glue<T> { private List<Type<T>> types; private Glue() { types = new ArrayList<Type<T>>(); } private static class Type<T> { private T value; /* some other properties, omitted for simplicity */ public Type(T value) { this.value = value; } } public static <T> Glue<T> glueFactory(String name, T first, T second) { Glue<T> g = new Glue<T>(); Type<T> firstType = new Glue.Type<T>(first); Type<T> secondType = new Glue.Type<T>(second); g.types.add(firstType); g.types.add(secondType); /* omitted complex stuff */ return g; } } As said, this works as intended. When the API user (=another developer) types Glue<Horse> strongGlue = Glue.glueFactory("2HP", new Horse(), new Horse()); he gets exactly what he wanted. What I'm missing is that how do I enforce that Horse - or whatever is put into the factory method - always implements both Serializable and Comparable? Simply adding them to factory method's signature using <T extends Comparable<T> & Serializable> doesn't necessarily enforce this rule in all cases, only when this simplified API is used. That's why I'd like to add them to the class' definition and then modify the factory method accordingly. PS: No horses (and definitely no ponies!) were harmed in writing of this question.

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  • java concurrency: many writers, one reader

    - by Janning
    I need to gather some statistics in my software and i am trying to make it fast and correct, which is not easy (for me!) first my code so far with two classes, a StatsService and a StatsHarvester public class StatsService { private Map<String, Long> stats = new HashMap<String, Long>(1000); public void notify ( String key ) { Long value = 1l; synchronized (stats) { if (stats.containsKey(key)) { value = stats.get(key) + 1; } stats.put(key, value); } } public Map<String, Long> getStats ( ) { Map<String, Long> copy; synchronized (stats) { copy = new HashMap<String, Long>(stats); stats.clear(); } return copy; } } this is my second class, a harvester which collects the stats from time to time and writes them to a database. public class StatsHarvester implements Runnable { private StatsService statsService; private Thread t; public void init ( ) { t = new Thread(this); t.start(); } public synchronized void run ( ) { while (true) { try { wait(5 * 60 * 1000); // 5 minutes collectAndSave(); } catch (InterruptedException e) { e.printStackTrace(); } } } private void collectAndSave ( ) { Map<String, Long> stats = statsService.getStats(); // do something like: // saveRecords(stats); } } At runtime it will have about 30 concurrent running threads each calling notify(key) about 100 times. Only one StatsHarvester is calling statsService.getStats() So i have many writers and only one reader. it would be nice to have accurate stats but i don't care if some records are lost on high concurrency. The reader should run every 5 Minutes or whatever is reasonable. Writing should be as fast as possible. Reading should be fast but if it locks for about 300ms every 5 minutes, its fine. I've read many docs (Java concurrency in practice, effective java and so on), but i have the strong feeling that i need your advice to get it right. I hope i stated my problem clear and short enough to get valuable help.

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  • How do you prevent IDisposable from spreading to all your classes?

    - by GrahamS
    Start with these simple classes... Let's say I have a simple set of classes like this: class Bus { Driver busDriver = new Driver(); } class Driver { Shoe[] shoes = { new Shoe(), new Shoe() }; } class Shoe { Shoelace lace = new Shoelace(); } class Shoelace { bool tied = false; } A Bus has a Driver, the Driver has two Shoes, each Shoe has a Shoelace. All very silly. Add an IDisposable object to Shoelace Later I decide that some operation on the Shoelace could be multi-threaded, so I add an EventWaitHandle for the threads to communicate with. So Shoelace now looks like this: class Shoelace { private AutoResetEvent waitHandle = new AutoResetEvent(false); bool tied = false; // ... other stuff .. } Implement IDisposable on Shoelace Buit now FxCop will complain: "Implement IDisposable on 'Shoelace' because it creates members of the following IDisposable types: 'EventWaitHandle'." Okay, I implement IDisposable on Shoelace and my neat little class becomes this horrible mess: class Shoelace : IDisposable { private AutoResetEvent waitHandle = new AutoResetEvent(false); bool tied = false; private bool disposed = false; public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } ~Shoelace() { Dispose(false); } protected virtual void Dispose(bool disposing) { if (!this.disposed) { if (disposing) { if (waitHandle != null) { waitHandle.Close(); waitHandle = null; } } // No unmanaged resources to release otherwise they'd go here. } disposed = true; } } Or (as pointed out by commenters) since Shoelace itself has no unmanaged resources, I might use the simpler dispose implementation without needing the Dispose(bool) and Destructor: class Shoelace : IDisposable { private AutoResetEvent waitHandle = new AutoResetEvent(false); bool tied = false; public void Dispose() { if (waitHandle != null) { waitHandle.Close(); waitHandle = null; } GC.SuppressFinalize(this); } } Watch in horror as IDisposable spreads Right that's that fixed. But now FxCop will complain that Shoe creates a Shoelace, so Shoe must be IDisposable too. And Driver creates Shoe so Driver must be IDisposable. and Bus creates Driver so Bus must be IDisposable and so on. Suddenly my small change to Shoelace is causing me a lot of work and my boss is wondering why I need to checkout Bus to make a change to Shoelace. The Question How do you prevent this spread of IDisposable, but still ensure that your unmanaged objects are properly disposed?

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  • question about book example - Java Concurrency in Practice, Listing 4.12

    - by mike
    Hi, I am working through an example in Java Concurrency in Practice and am not understanding why a concurrent-safe container is necessary in the following code. I'm not seeing how the container "locations" 's state could be modified after construction; so since it is published through an 'unmodifiableMap' wrapper, it appears to me that an ordinary HashMap would suffice. EG, it is accessed concurrently, but the state of the map is only accessed by readers, no writers. The value fields in the map are syncronized via delegation to the 'SafePoint' class, so while the points are mutable, the keys for the hash, and their associated values (references to SafePoint instances) in the map never change. I think my confusion is based on what precisely the state of the collection is in the problem. Thanks!! -Mike Listing 4.12, Java Concurrency in Practice, (this listing available as .java here, and also in chapter form via google) /////////////begin code @ThreadSafe public class PublishingVehicleTracker { private final Map<String, SafePoint> locations; private final Map<String, SafePoint> unmodifiableMap; public PublishingVehicleTracker( Map<String, SafePoint> locations) { this.locations = new ConcurrentHashMap<String, SafePoint>(locations); this.unmodifiableMap = Collections.unmodifiableMap(this.locations); } public Map<String, SafePoint> getLocations() { return unmodifiableMap; } public SafePoint getLocation(String id) { return locations.get(id); } public void setLocation(String id, int x, int y) { if (!locations.containsKey(id)) throw new IllegalArgumentException( "invalid vehicle name: " + id); locations.get(id).set(x, y); } } // monitor protected helper-class @ThreadSafe public class SafePoint { @GuardedBy("this") private int x, y; private SafePoint(int[] a) { this(a[0], a[1]); } public SafePoint(SafePoint p) { this(p.get()); } public SafePoint(int x, int y) { this.x = x; this.y = y; } public synchronized int[] get() { return new int[] { x, y }; } public synchronized void set(int x, int y) { this.x = x; this.y = y; } } ///////////end code

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  • Mocking a concrete class : templates and avoiding conditional compilation

    - by AshirusNW
    I'm trying to testing a concrete object with this sort of structure. class Database { public: Database(Server server) : server_(server) {} int Query(const char* expression) { server_.Connect(); return server_.ExecuteQuery(); } private: Server server_; }; i.e. it has no virtual functions, let alone a well-defined interface. I want to a fake database which calls mock services for testing. Even worse, I want the same code to be either built against the real version or the fake so that the same testing code can both: Test the real Database implementation - for integration tests Test the fake implementation, which calls mock services To solve this, I'm using a templated fake, like this: #ifndef INTEGRATION_TESTS class FakeDatabase { public: FakeDatabase() : realDb_(mockServer_) {} int Query(const char* expression) { MOCK_EXPECT_CALL(mockServer_, Query, 3); return realDb_.Query(); } private: // in non-INTEGRATION_TESTS builds, Server is a mock Server with // extra testing methods that allows mocking Server mockServer_; Database realDb_; }; #endif template <class T> class TestDatabaseContainer { public: int Query(const char* expression) { int result = database_.Query(expression); std::cout << "LOG: " << result << endl; return result; } private: T database_; }; Edit: Note the fake Database must call the real Database (but with a mock Server). Now to switch between them I'm planning the following test framework: class DatabaseTests { public: #ifdef INTEGRATION_TESTS typedef TestDatabaseContainer<Database> TestDatabase ; #else typedef TestDatabaseContainer<FakeDatabase> TestDatabase ; #endif TestDatabase& GetDb() { return _testDatabase; } private: TestDatabase _testDatabase; }; class QueryTestCase : public DatabaseTests { public: void TestStep1() { ASSERT(GetDb().Query(static_cast<const char *>("")) == 3); return; } }; I'm not a big fan of that compile-time switching between the real and the fake. So, my question is: Whether there's a better way of switching between Database and FakeDatabase? For instance, is it possible to do it at runtime in a clean fashion? I like to avoid #ifdefs. Also, if anyone has a better way of making a fake class that mimics a concrete class, I'd appreciate it. I don't want to have templated code all over the actual test code (QueryTestCase class). Feel free to critique the code style itself, too. You can see a compiled version of this code on codepad.

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  • Create a CSR in C# using an explicit RSA key-pair

    - by rlandster
    Using the OpenSSL libraries one can create a CSR (certificate signing request) by doing this: openssl genrsa -out rsa.key 1024 openssl req -new -key rsa.key -out output.csr -config config.txt where config.txt contains the distinguished name to use in the certificate. I would like to do something similar under Windows using C#. However, the method createPKCS10 does not require you to supply an RSA key. Is there a way to get C# to generate an explicit RSA private key and then use that private key to create the CSR?

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  • Deriving from a component and implementing IDisposable properly

    - by PaulH
    I have a Visual Studio 2008 C# .NET 2.0 CF project with an abstract class derived from Component. From that class, I derive several concrete classes (as in my example below). But, when I go to exit my Form, though the Form's Dispose() member is called and components.Dispose() is called, my components are never disposed. Can anybody suggest how I can fix this design? public abstract class SomeDisposableComponentBase : Component { private System.ComponentModel.IContainer components; protected SomeDisposableComponentBase() { Initializecomponent(); } protected SomeDisposableComponentBase(IContainer container) { container.Add(this); Initializecomponent(); } private void InitializeComponent() { components = new System.ComponentModel.Container(); } protected abstract void Foo(); #region IDisposable Members bool disposed_; /// Warning 60 CA1063 : Microsoft.Design : Ensure that 'SomeDisposableComponentBase.Dispose()' is declared as public and sealed.* public void Dispose() { // never called Dispose(true); GC.SuppressFinalize(this); } protected virtual void Dispose(bool disposing) { // never called if (!disposed_) { if (disposing && (components != null)) { components.Dispose(); } disposed_ = true; } base.Dispose(disposing); } #endregion } public SomeDisposableComponent : SomeDisposableComponentBase { public SomeDisposableComponent() : base() { } public SomeDisposableComponent(IContainer container) : base(container) { } protected override void Foo() { // Do something... } protected override void Dispose(bool disposing) { // never called base.Dispose(disposing); } } public partial class my_form : Form { private SomeDisposableComponentBase d_; public my_form() { InitializeComponent(); if (null == components) components = new System.ComponentModel.Container(); d_ = new SomeDisposableComponent(components); } /// exit button clicked private void Exit_Click(object sender, EventArgs e) { this.Close(); } /// from the my_form.designer.cs protected override void Dispose(bool disposing) { if (disposing && (components != null)) { // this function is executed as expected when the form is closed components.Dispose(); } base.Dispose(disposing); } } *I note that FX-Cop is giving me a hint here. But, if I try to declare that function as sealed, I get the error: error CS0238: 'SomeDisposableComponentBase.Dispose()' cannot be sealed because it is not an override Declaring that function an override leads to: 'SomeDisposableComponentBase.Dispose()': cannot override inherited member 'System.ComponentModel.Component.Dispose()' because it is not marked virtual, abstract, or override Thanks, PaulH

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  • Android: roatating images in a loop.

    - by user573736
    Hello, I am trying with no success to modify the code example from: http://www.inter-fuser.com/2009/08/android-animations-3d-flip.html so it will rotate the images in a loop, when clicking on the image once. (second click should pause). I tried using Handler and threading but cannot update the view since only the main thread can update UI. Exception I get from the code below: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. [in 'image1.startAnimation(rotation);' ('applyRotation(0, 90);' from the main thread)] package com.example.flip3d; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.animation.AccelerateInterpolator; import android.widget.ImageView; public class Flip3d extends Activity { private ImageView image1; private ImageView image2; private boolean isFirstImage = true; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); image1 = (ImageView) findViewById(R.id.image01); image2 = (ImageView) findViewById(R.id.image02); image2.setVisibility(View.GONE); image1.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { if (isFirstImage) { applyRotation(0, 90); isFirstImage = !isFirstImage; } else { applyRotation(0, -90); isFirstImage = !isFirstImage; } } }); } private void applyRotation(float start, float end) { // Find the center of image final float centerX = image1.getWidth() / 2.0f; final float centerY = image1.getHeight() / 2.0f; // Create a new 3D rotation with the supplied parameter // The animation listener is used to trigger the next animation final Flip3dAnimation rotation = new Flip3dAnimation(start, end, centerX, centerY); rotation.setDuration(500); rotation.setFillAfter(true); rotation.setInterpolator(new AccelerateInterpolator()); rotation.setAnimationListener(new DisplayNextView(isFirstImage, image1, image2)); if (isFirstImage) { image1.startAnimation(rotation); } else { image2.startAnimation(rotation); } } } How can I manage to update the UI and control the rotation within onClick listener? Thank you, Oakist

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  • How to inherit events between objects

    - by marduck19
    I need inherit events and properties for example move a picture around the form Y have this code to move the picture but y need create multiple images with the same behavior private void pictureBox_MouseDown(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Left) { x = e.X; y = e.Y; } } private void pictureBox_MouseMove(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Left) { pictureBox.Left += (e.X -x); pictureBox.Top += (e.Y - y); } }

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