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  • How to generalize a method call in Java (to avoid code duplication)

    - by dln385
    I have a process that needs to call a method and return its value. However, there are several different methods that this process may need to call, depending on the situation. If I could pass the method and its arguments to the process (like in Python), then this would be no problem. However, I don't know of any way to do this in Java. Here's a concrete example. (This example uses Apache ZooKeeper, but you don't need to know anything about ZooKeeper to understand the example.) The ZooKeeper object has several methods that will fail if the network goes down. In this case, I always want to retry the method. To make this easy, I made a "BetterZooKeeper" class that inherits the ZooKeeper class, and all of its methods automatically retry on failure. This is what the code looked like: public class BetterZooKeeper extends ZooKeeper { private void waitForReconnect() { // logic } @Override public Stat exists(String path, Watcher watcher) { while (true) { try { return super.exists(path, watcher); } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } @Override public byte[] getData(String path, boolean watch, Stat stat) { while (true) { try { return super.getData(path, watch, stat); } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } @Override public void delete(String path, int version) { while (true) { try { super.delete(path, version); return; } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } } (In the actual program there is much more logic and many more methods that I took out of the example for simplicity.) We can see that I'm using the same retry logic, but the arguments, method call, and return type are all different for each of the methods. Here's what I did to eliminate the duplication of code: public class BetterZooKeeper extends ZooKeeper { private void waitForReconnect() { // logic } @Override public Stat exists(final String path, final Watcher watcher) { return new RetryableZooKeeperAction<Stat>() { @Override public Stat action() { return BetterZooKeeper.super.exists(path, watcher); } }.run(); } @Override public byte[] getData(final String path, final boolean watch, final Stat stat) { return new RetryableZooKeeperAction<byte[]>() { @Override public byte[] action() { return BetterZooKeeper.super.getData(path, watch, stat); } }.run(); } @Override public void delete(final String path, final int version) { new RetryableZooKeeperAction<Object>() { @Override public Object action() { BetterZooKeeper.super.delete(path, version); return null; } }.run(); return; } private abstract class RetryableZooKeeperAction<T> { public abstract T action(); public final T run() { while (true) { try { return action(); } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } } } The RetryableZooKeeperAction is parameterized with the return type of the function. The run() method holds the retry logic, and the action() method is a placeholder for whichever ZooKeeper method needs to be run. Each of the public methods of BetterZooKeeper instantiates an anonymous inner class that is a subclass of the RetryableZooKeeperAction inner class, and it overrides the action() method. The local variables are (strangely enough) implicitly passed to the action() method, which is possible because they are final. In the end, this approach does work and it does eliminate the duplication of the retry logic. However, it has two major drawbacks: (1) it creates a new object every time a method is called, and (2) it's ugly and hardly readable. Also I had to workaround the 'delete' method which has a void return value. So, here is my question: is there a better way to do this in Java? This can't be a totally uncommon task, and other languages (like Python) make it easier by allowing methods to be passed. I suspect there might be a way to do this through reflection, but I haven't been able to wrap my head around it.

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  • Algorithm for dynamic combinations

    - by sOltan
    My code has a list called INPUTS, that contains a dynamic number of lists, let's call them A, B, C, .. N. These lists contain a dynamic number of Events I would like to call a function with each combination of Events. To illustrate with an example: INPUTS: A(0,1,2), B(0,1), C(0,1,2,3) I need to call my function this many times for each combination (the input count is dynamic, in this example it is three parameter, but it can be more or less) function(A[0],B[0],C[0]) function(A[0],B[1],C[0]) function(A[0],B[0],C[1]) function(A[0],B[1],C[1]) function(A[0],B[0],C[2]) function(A[0],B[1],C[2]) function(A[0],B[0],C[3]) function(A[0],B[1],C[3]) function(A[1],B[0],C[0]) function(A[1],B[1],C[0]) function(A[1],B[0],C[1]) function(A[1],B[1],C[1]) function(A[1],B[0],C[2]) function(A[1],B[1],C[2]) function(A[1],B[0],C[3]) function(A[1],B[1],C[3]) function(A[2],B[0],C[0]) function(A[2],B[1],C[0]) function(A[2],B[0],C[1]) function(A[2],B[1],C[1]) function(A[2],B[0],C[2]) function(A[2],B[1],C[2]) function(A[2],B[0],C[3]) function(A[2],B[1],C[3]) This is what I have thought of so far: My approach so far is to build a list of combinations. The element combination is itself a list of "index" to the input arrays A, B and C. For our example: my list iCOMBINATIONS contains the following iCOMBO lists (0,0,0) (0,1,0) (0,0,1) (0,1,1) (0,0,2) (0,1,2) (0,0,3) (0,1,3) (1,0,0) (1,1,0) (1,0,1) (1,1,1) (1,0,2) (1,1,2) (1,0,3) (1,1,3) (2,0,0) (2,1,0) (2,0,1) (2,1,1) (2,0,2) (2,1,2) (2,0,3) (2,1,3) Then I would do this: foreach( iCOMBO in iCOMBINATIONS) { foreach ( P in INPUTS ) { COMBO.Clear() foreach ( i in iCOMBO ) { COMBO.Add( P[ iCOMBO[i] ] ) } function( COMBO ) --- (instead of passing the events separately) } } But I need to find a way to build the list iCOMBINATIONS for any given number of INPUTS and their events. Any ideas? Is there actually a better algorithm than this? any pseudo code to help me with will be great. C# (or VB) Thank You

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  • listView dynamic add item

    - by pengwang
    hello,I used ListView to dynamic add item,but there is a problem about not Smooth add. there are textView and button in my listActivity,Iwant to Press button ,then textView"s text can auto add to listView,but i Pressed button ,it donot work,unless after i enter content , press "OK"Key ,then Pressed button ,textView"s text can auto add to listView. I donot know why. if I continuous Pressed button ,as3 times, then press "Ok"Key ,the content auto add list View but 3 times. public class DynamicListItems extends ListActivity { private static final String ITEM_KEY = "key"; ArrayList<HashMap<String, String>> list= new ArrayList<HashMap<String, String>>(); private SimpleAdapter adapter; private EditText newValue;@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.dynamic_list); newValue = (EditText) findViewById(R.id.new_value_field); setListAdapter(new SimpleAdapter(this, list, R.layout.row, new String[] { ITEM_KEY }, new int[] { R.id.list_value })); ((ImageButton) findViewById(R.id.button)).setOnClickListener(getBtnClickListener()); } private OnClickListener getBtnClickListener() { return new OnClickListener() { public void onClick(View view) { try { HashMap<String, String> item = new HashMap<String, String>(); item.put(ITEM_KEY, newValue.getText().toString()); list.add(item); adapter.notifyDataSetChanged(); } catch (NullPointerException e) { Log.i("[Dynamic Items]", "Tried to add null value"); } } }; }} my another question is how to dynamic delete the item,which event i need to used,could you give me some directions or Code snippets? dynamic_list.xml only contains listView ,button,textView row.xml contains TextView . i amm sorry i donot edit code together.

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  • Question - Setting dynamic HTML using Javascript to iFrames on Windows Mobile 6.1 - IE Mobile6

    - by swaroop
    Hi Experts, (excuse me if this is not the right forum to post - i couldn't find anything related to non-native programming and related to this topic) I Am trying to set a dynamic HTML into an iFrame on the webpage. I have tried a couple of things but none of them seem to work. I m able to read the innerHTML but can't seem to update it. // Able to read using document.getElementById('iFrameIdentifier').innerHTML; // On Desktop IE, this code works document.getElementById('iFrameId').contentWindow.document.open(); document.getElementById('iFrameId').contentWindow.document.write(dynamicHTML); document.getElementById('iFrameId').contentWindow.document.close(); Ideally the same function should work as how it works for div's but it says 'Object doesn't support this method or property". I have also tried document.getElementById('iFrameId').document.body.innerHTML. This apparently replaces the whole HTML of the page and not just the innerHTML. I have tried out a couple of things and they didn't work document.getElementById('iFrameId').body.innerHTML document.frames[0].document.body.innerHTML My purpose is to have a container element which can contain dynamic HTML that's set to it. I've been using it well till now when I observed that the setting innerHTML on a div is taking increasing amount of time because of the onClicks or other JS methods that are attached to the anchors and images in the dynamic HTML. Appears the JS methods or the HTML is some how not getting cleaned up properly (memory leak?) Also being discussed - http://www.experts-exchange.com/Programming/Languages/Scripting/JavaScript/Q_26185526.html#a32779090

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  • ildasm and dynamic exe files

    - by TonyNeallon
    Hi There, I am trying to create an application can modify properties in IL to create a slightly different executable. E.g Client A runs app and a label on the WinForm label Reads "Client A:". Client B runs the app and Label Says "Client B". Easy I know using config files or resource files but thats not an option for this project. The Main program needs to be able to generate .exe file dynamically based on some form fields entered by user. My solution was to create a standalone executable that contained all the elements which I needed to make dynamic. I then used ildasm to generate the IL and thought that I could use this IL and substitute tags for the elements i wanted to make dynamic. I could then replace those tags at runtime after user filled the form using regex etc. The problem is, the if i re save the IL file generated by ILDASM as an exe and try to run it. I just launches console and does nothing. Am I going about this the wrong way? I didnt want to delve into Reflection as the dynamic .exe is a really simple one and I thought reverse engineering IL with ildasm would be the quickest way. You thoughts and pointers are much appreciated. Tony

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  • JSF 2.0 Dynamic Views

    - by Robe Eleckers
    Hello, I'm working on a web project which uses JSF 2.0, PrimeFaces and PrettyFaces as main frameworks / libraries. The pages have the following (common) structure: Header, Content, Footer. Header: The Header always contains the same menu. This menu is a custom component, which generates a recursive html <ul><li> list containing <a href="url"> html links, this is all rendered with a custom renderer. The link looks like 'domain.com/website/datatable.xhtml?ref=2'. Where the ref=2 used to load the correct content from the database. I use prettyfaces to store this request value in a backingbean. Question 1: Is it ok to render the <a href> links myself, or should I better add an HTMLCommandLink from my UIComponent and render that in the encodeBegin/End? Question 2: I think passing variables like this is not really the JSF 2.0 style, how to do this in a better way? Content: The content contains dynamic data. It can be a (primefaces) datatable, build with dynamic data from the database. It can also be a text page, also loaded from the database. Or a series of graphs. You got the point, it's dynamic. The content is based on the link pressed in the header menu. If the content is of type datatable, then I put the ref=2 variable to a DataTableBean (via prettyfaces), which then loads the correct datatable from the database. If the content is of type chart, I'll put it on the ChartBean. Question 3: Is this a normal setup? Ideally I would like to update my content via Ajax. I hope it's clear :)

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  • Unable to change URL for .NET reference to dynamic web service

    - by Malvineous
    Hi all, I have a web reference added to a C# .NET project. The URL for the web reference needs to change depending on whether I'm building for a development, staging or production environment. I've set the web service to be dynamic, which supposedly means it takes the URL from my app.config file. When I perform a build it overwrites the app.config with the required file which contains the correct URL (different file for each of dev/staging/production.) I then go into the solution properties and make sure the Settings.settings file is updated with the app.config changes. However when I view the properties for the web service, it is still showing the old URL, despite it being dynamic, and supposed to be reading from my settings file (even after closing and reopening the project/solution.) The app.config and the settings file all have the new URL, but the web reference doesn't notice it has changed. If I do a build it ignores the URL in the settings file and tries to connect to the last URL manually typed into the web reference's properties. Typing a URL into these properties correctly updates the app.config and .settings files, so the link is definitely there. I'm a bit new to .NET but it seems to me the purpose of setting the service to be dynamic is so that you can change the URL elsewhere, but when I do this it just gets ignored! Am I doing something wrong?

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  • Add dynamic charts using ASP.NET CHART CONTROL, c#

    - by dhareni
    I wanted to add dynamic charts in the webpage. It goes like this... I get the start and end date from user and draw separate charts for each date bewteen the start and end date. I get the data from sql database and bind it with the chart like this: SqlConnection UsageLogConn = new SqlConnection(ConfigurationManager.ConnectionStrings["UsageConn"].ConnectionString); UsageLogConn.Open();//open connection string sql = "SELECT v.interval,dateadd(mi,(v.interval-1)*2,'" + startdate + " 00:00:00') as 'intervaltime',COUNT(Datediff(minute,'" + startdate + " 00:00:00',d.DateTime)/2) AS Total FROM usage_internet_intervals v left outer join (select * from Usage_Internet where " + name + " LIKE ('%" + value + "%') and DateTime BETWEEN '" + startdate + " 00:00:00' AND '" + enddate + " 23:59:59') d on v.interval = Datediff(minute,'" + startdate + " 00:00:00',d.DateTime)/2 GROUP BY v.interval,Datediff(minute,'" + startdate + " 00:00:00',d.DateTime)/2 ORDER BY Interval"; SqlCommand cmd = new SqlCommand(sql, UsageLogConn); SqlDataAdapter mySQLadapter = new SqlDataAdapter(cmd); Chart1.DataSource = cmd; // set series members names for the X and Y values Chart1.Series["Series 1"].XValueMember = "intervaltime"; Chart1.Series["Series 1"].YValueMembers = "Total"; UsageLogConn.Close(); // data bind to the selected data source Chart1.DataBind(); cmd.Dispose(); The above code adds only one chart for one date and I have added 'chart1' to design view and its not created dynamic. But I wanted to add more charts dynamic at runtime to the webpage. Can anyone help me with this? I am using VS 2008, ASP.NET 3.5 and the charting lib is: using System.Web.UI.DataVisualization.Charting;

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  • Built-in GZip/Deflate Compression on IIS 7.x

    - by Rick Strahl
    IIS 7 improves internal compression functionality dramatically making it much easier than previous versions to take advantage of compression that’s built-in to the Web server. IIS 7 also supports dynamic compression which allows automatic compression of content created in your own applications (ASP.NET or otherwise!). The scheme is based on content-type sniffing and so it works with any kind of Web application framework. While static compression on IIS 7 is super easy to set up and turned on by default for most text content (text/*, which includes HTML and CSS, as well as for JavaScript, Atom, XAML, XML), setting up dynamic compression is a bit more involved, mostly because the various default compression settings are set in multiple places down the IIS –> ASP.NET hierarchy. Let’s take a look at each of the two approaches available: Static Compression Compresses static content from the hard disk. IIS can cache this content by compressing the file once and storing the compressed file on disk and serving the compressed alias whenever static content is requested and it hasn’t changed. The overhead for this is minimal and should be aggressively enabled. Dynamic Compression Works against application generated output from applications like your ASP.NET apps. Unlike static content, dynamic content must be compressed every time a page that requests it regenerates its content. As such dynamic compression has a much bigger impact than static caching. How Compression is configured Compression in IIS 7.x  is configured with two .config file elements in the <system.WebServer> space. The elements can be set anywhere in the IIS/ASP.NET configuration pipeline all the way from ApplicationHost.config down to the local web.config file. The following is from the the default setting in ApplicationHost.config (in the %windir%\System32\inetsrv\config forlder) on IIS 7.5 with a couple of small adjustments (added json output and enabled dynamic compression): <?xml version="1.0" encoding="UTF-8"?> <configuration> <system.webServer> <httpCompression directory="%SystemDrive%\inetpub\temp\IIS Temporary Compressed Files"> <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" /> <dynamicTypes> <add mimeType="text/*" enabled="true" /> <add mimeType="message/*" enabled="true" /> <add mimeType="application/x-javascript" enabled="true" /> <add mimeType="application/json" enabled="true" /> <add mimeType="*/*" enabled="false" /> </dynamicTypes> <staticTypes> <add mimeType="text/*" enabled="true" /> <add mimeType="message/*" enabled="true" /> <add mimeType="application/x-javascript" enabled="true" /> <add mimeType="application/atom+xml" enabled="true" /> <add mimeType="application/xaml+xml" enabled="true" /> <add mimeType="*/*" enabled="false" /> </staticTypes> </httpCompression> <urlCompression doStaticCompression="true" doDynamicCompression="true" /> </system.webServer> </configuration> You can find documentation on the httpCompression and urlCompression keys here respectively: http://msdn.microsoft.com/en-us/library/ms690689%28v=vs.90%29.aspx http://msdn.microsoft.com/en-us/library/aa347437%28v=vs.90%29.aspx The httpCompression Element – What and How to compress Basically httpCompression configures what types to compress and how to compress them. It specifies the DLL that handles gzip encoding and the types of documents that are to be compressed. Types are set up based on mime-types which looks at returned Content-Type headers in HTTP responses. For example, I added the application/json to mime type to my dynamic compression types above to allow that content to be compressed as well since I have quite a bit of AJAX content that gets sent to the client. The UrlCompression Element – Enables and Disables Compression The urlCompression element is a quick way to turn compression on and off. By default static compression is enabled server wide, and dynamic compression is disabled server wide. This might be a bit confusing because the httpCompression element also has a doDynamicCompression attribute which is set to true by default, but the urlCompression attribute by the same name actually overrides it. The urlCompression element only has three attributes: doStaticCompression, doDynamicCompression and dynamicCompressionBeforeCache. The doCompression attributes are the final determining factor whether compression is enabled, so it’s a good idea to be explcit! The default for doDynamicCompression='false”, but doStaticCompression="true"! Static Compression is enabled by Default, Dynamic Compression is not Because static compression is very efficient in IIS 7 it’s enabled by default server wide and there probably is no reason to ever change that setting. Dynamic compression however, since it’s more resource intensive, is turned off by default. If you want to enable dynamic compression there are a few quirks you have to deal with, namely that enabling it in ApplicationHost.config doesn’t work. Setting: <urlCompression doDynamicCompression="true" /> in applicationhost.config appears to have no effect and I had to move this element into my local web.config to make dynamic compression work. This is actually a smart choice because you’re not likely to want dynamic compression in every application on a server. Rather dynamic compression should be applied selectively where it makes sense. However, nowhere is it documented that the setting in applicationhost.config doesn’t work (or more likely is overridden somewhere and disabled lower in the configuration hierarchy). So: remember to set doDynamicCompression=”true” in web.config!!! How Static Compression works Static compression works against static content loaded from files on disk. Because this content is static and not bound to change frequently – such as .js, .css and static HTML content – it’s fairly easy for IIS to compress and then cache the compressed content. The way this works is that IIS compresses the files into a special folder on the server’s hard disk and then reads the content from this location if already compressed content is requested and the underlying file resource has not changed. The semantics of serving an already compressed file are very efficient – IIS still checks for file changes, but otherwise just serves the already compressed file from the compression folder. The compression folder is located at: %windir%\inetpub\temp\IIS Temporary Compressed Files\ApplicationPool\ If you look into the subfolders you’ll find compressed files: These files are pre-compressed and IIS serves them directly to the client until the underlying files are changed. As I mentioned before – static compression is on by default and there’s very little reason to turn that functionality off as it is efficient and just works out of the box. The one tweak you might want to do is to set the compression level to maximum. Since IIS only compresses content very infrequently it would make sense to apply maximum compression. You can do this with the staticCompressionLevel setting on the scheme element: <scheme name="gzip" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" /> Other than that the default settings are probably just fine. Dynamic Compression – not so fast! By default dynamic compression is disabled and that’s actually quite sensible – you should use dynamic compression very carefully and think about what content you want to compress. In most applications it wouldn’t make sense to compress *all* generated content as it would generate a significant amount of overhead. Scott Fortsyth has a great post that details some of the performance numbers and how much impact dynamic compression has. Depending on how busy your server is you can play around with compression and see what impact it has on your server’s performance. There are also a few settings you can tweak to minimize the overhead of dynamic compression. Specifically the httpCompression key has a couple of CPU related keys that can help minimize the impact of Dynamic Compression on a busy server: dynamicCompressionDisableCpuUsage dynamicCompressionEnableCpuUsage By default these are set to 90 and 50 which means that when the CPU hits 90% compression will be disabled until CPU utilization drops back down to 50%. Again this is actually quite sensible as it utilizes CPU power from compression when available and falling off when the threshold has been hit. It’s a good way some of that extra CPU power on your big servers to use when utilization is low. Again these settings are something you likely have to play with. I would probably set the upper limit a little lower than 90% maybe around 70% to make this a feature that kicks in only if there’s lots of power to spare. I’m not really sure how accurate these CPU readings that IIS uses are as Cpu usage on Web Servers can spike drastically even during low loads. Don’t trust settings – do some load testing or monitor your server in a live environment to see what values make sense for your environment. Finally for dynamic compression I tend to add one Mime type for JSON data, since a lot of my applications send large chunks of JSON data over the wire. You can do that with the application/json content type: <add mimeType="application/json" enabled="true" /> What about Deflate Compression? The default compression is GZip. The documentation hints that you can use a different compression scheme and mentions Deflate compression. And sure enough you can change the compression settings to: <scheme name="deflate" dll="%Windir%\system32\inetsrv\gzip.dll" staticCompressionLevel="9" /> to get deflate style compression. The deflate algorithm produces slightly more compact output so I tend to prefer it over GZip but more HTTP clients (other than browsers) support GZip than Deflate so be careful with this option if you build Web APIs. I also had some issues with the above value actually being applied right away. Changing the scheme in applicationhost.config didn’t show up on the site  right away. It required me to do a full IISReset to get that change to show up before I saw the change over to deflate compressed content. Content was slightly more compressed with deflate – not sure if it’s worth the slightly less common compression type, but the option at least is available. IIS 7 finally makes GZip Easy In summary IIS 7 makes GZip easy finally, even if the configuration settings are a bit obtuse and the documentation is seriously lacking. But once you know the basic settings I’ve described here and the fact that you can override all of this in your local web.config it’s pretty straight forward to configure GZip support and tweak it exactly to your needs. Static compression is a total no brainer as it adds very little overhead compared to direct static file serving and provides solid compression. Dynamic Compression is a little more tricky as it does add some overhead to servers, so it probably will require some tweaking to get the right balance of CPU load vs. compression ratios. Looking at large sites like Amazon, Yahoo, NewEgg etc. – they all use Related Content Code based ASP.NET GZip Caveats HttpWebRequest and GZip Responses © Rick Strahl, West Wind Technologies, 2005-2011Posted in IIS7   ASP.NET  

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  • Revisiting ANTS Performance Profiler 7.4

    - by James Michael Hare
    Last year, I did a small review on the ANTS Performance Profiler 6.3, now that it’s a year later and a major version number higher, I thought I’d revisit the review and revise my last post. This post will take the same examples as the original post and update them to show what’s new in version 7.4 of the profiler. Background A performance profiler’s main job is to keep track of how much time is typically spent in each unit of code. This helps when we have a program that is not running at the performance we expect, and we want to know where the program is experiencing issues. There are many profilers out there of varying capabilities. Red Gate’s typically seem to be the very easy to “jump in” and get started with very little training required. So let’s dig into the Performance Profiler. I’ve constructed a very crude program with some obvious inefficiencies. It’s a simple program that generates random order numbers (or really could be any unique identifier), adds it to a list, sorts the list, then finds the max and min number in the list. Ignore the fact it’s very contrived and obviously inefficient, we just want to use it as an example to show off the tool: 1: // our test program 2: public static class Program 3: { 4: // the number of iterations to perform 5: private static int _iterations = 1000000; 6: 7: // The main method that controls it all 8: public static void Main() 9: { 10: var list = new List<string>(); 11: 12: for (int i = 0; i < _iterations; i++) 13: { 14: var x = GetNextId(); 15: 16: AddToList(list, x); 17: 18: var highLow = GetHighLow(list); 19: 20: if ((i % 1000) == 0) 21: { 22: Console.WriteLine("{0} - High: {1}, Low: {2}", i, highLow.Item1, highLow.Item2); 23: Console.Out.Flush(); 24: } 25: } 26: } 27: 28: // gets the next order id to process (random for us) 29: public static string GetNextId() 30: { 31: var random = new Random(); 32: var num = random.Next(1000000, 9999999); 33: return num.ToString(); 34: } 35: 36: // add it to our list - very inefficiently! 37: public static void AddToList(List<string> list, string item) 38: { 39: list.Add(item); 40: list.Sort(); 41: } 42: 43: // get high and low of order id range - very inefficiently! 44: public static Tuple<int,int> GetHighLow(List<string> list) 45: { 46: return Tuple.Create(list.Max(s => Convert.ToInt32(s)), list.Min(s => Convert.ToInt32(s))); 47: } 48: } So let’s run it through the profiler and see what happens! Visual Studio Integration First, let’s look at how the ANTS profilers integrate with Visual Studio’s menu system. Once you install the ANTS profilers, you will get an ANTS menu item with several options: Notice that you can either Profile Performance or Launch ANTS Performance Profiler. These sound similar but achieve two slightly different actions: Profile Performance: this immediately launches the profiler with all defaults selected to profile the active project in Visual Studio. Launch ANTS Performance Profiler: this launches the profiler much the same way as starting it from the Start Menu. The profiler will pre-populate the application and path information, but allow you to change the settings before beginning the profile run. So really, the main difference is that Profile Performance immediately begins profiling with the default selections, where Launch ANTS Performance Profiler allows you to change the defaults and attach to an already-running application. Let’s Fire it Up! So when you fire up ANTS either via Start Menu or Launch ANTS Performance Profiler menu in Visual Studio, you are presented with a very simple dialog to get you started: Notice you can choose from many different options for application type. You can profile executables, services, web applications, or just attach to a running process. In fact, in version 7.4 we see two new options added: ASP.NET Web Application (IIS Express) SharePoint web application (IIS) So this gives us an additional way to profile ASP.NET applications and the ability to profile SharePoint applications as well. You can also choose your level of detail in the Profiling Mode drop down. If you choose Line-Level and method-level timings detail, you will get a lot more detail on the method durations, but this will also slow down profiling somewhat. If you really need the profiler to be as unintrusive as possible, you can change it to Sample method-level timings. This is performing very light profiling, where basically the profiler collects timings of a method by examining the call-stack at given intervals. Which method you choose depends a lot on how much detail you need to find the issue and how sensitive your program issues are to timing. So for our example, let’s just go with the line and method timing detail. So, we check that all the options are correct (if you launch from VS2010, the executable and path are filled in already), and fire it up by clicking the [Start Profiling] button. Profiling the Application Once you start profiling the application, you will see a real-time graph of CPU usage that will indicate how much your application is using the CPU(s) on your system. During this time, you can select segments of the graph and bookmark them, giving them mnemonic names. This can be useful if you want to compare performance in one part of the run to another part of the run. Notice that once you select a block, it will give you the call tree breakdown for that selection only, and the relative performance of those calls. Once you feel you have collected enough information, you can click [Stop Profiling] to stop the application run and information collection and begin a more thorough analysis. Analyzing Method Timings So now that we’ve halted the run, we can look around the GUI and see what we can see. By default, the times are shown in terms of percentage of time of the total run of the application, though you can change it in the View menu item to milliseconds, ticks, or seconds as well. This won’t affect the percentages of methods, it only affects what units the times are shown. Notice also that the major hotspot seems to be in a method without source, ANTS Profiler will filter these out by default, but you can right-click on the line and remove the filter to see more detail. This proves especially handy when a bottleneck is due to a method in the BCL. So now that we’ve removed the filter, we see a bit more detail: In addition, ANTS Performance Profiler gives you the ability to decompile the methods without source so that you can dive even deeper, though typically this isn’t necessary for our purposes. When looking at timings, there are generally two types of timings for each method call: Time: This is the time spent ONLY in this method, not including calls this method makes to other methods. Time With Children: This is the total of time spent in both this method AND including calls this method makes to other methods. In other words, the Time tells you how much work is being done exclusively in this method, and the Time With Children tells you how much work is being done inclusively in this method and everything it calls. You can also choose to display the methods in a tree or in a grid. The tree view is the default and it shows the method calls arranged in terms of the tree representing all method calls and the parent method that called them, etc. This is useful for when you find a hot-spot method, you can see who is calling it to determine if the problem is the method itself, or if it is being called too many times. The grid method represents each method only once with its totals and is useful for quickly seeing what method is the trouble spot. In addition, you can choose to display Methods with source which are generally the methods you wrote (as opposed to native or BCL code), or Any Method which shows not only your methods, but also native calls, JIT overhead, synchronization waits, etc. So these are just two ways of viewing the same data, and you’re free to choose the organization that best suits what information you are after. Analyzing Method Source If we look at the timings above, we see that our AddToList() method (and in particular, it’s call to the List<T>.Sort() method in the BCL) is the hot-spot in this analysis. If ANTS sees a method that is consuming the most time, it will flag it as a hot-spot to help call out potential areas of concern. This doesn’t mean the other statistics aren’t meaningful, but that the hot-spot is most likely going to be your biggest bang-for-the-buck to concentrate on. So let’s select the AddToList() method, and see what it shows in the source window below: Notice the source breakout in the bottom pane when you select a method (from either tree or grid view). This shows you the timings in this method per line of code. This gives you a major indicator of where the trouble-spot in this method is. So in this case, we see that performing a Sort() on the List<T> after every Add() is killing our performance! Of course, this was a very contrived, duh moment, but you’d be surprised how many performance issues become duh moments. Note that this one line is taking up 86% of the execution time of this application! If we eliminate this bottleneck, we should see drastic improvement in the performance. So to fix this, if we still wanted to maintain the List<T> we’d have many options, including: delay Sort() until after all Add() methods, using a SortedSet, SortedList, or SortedDictionary depending on which is most appropriate, or forgoing the sorting all together and using a Dictionary. Rinse, Repeat! So let’s just change all instances of List<string> to SortedSet<string> and run this again through the profiler: Now we see the AddToList() method is no longer our hot-spot, but now the Max() and Min() calls are! This is good because we’ve eliminated one hot-spot and now we can try to correct this one as well. As before, we can then optimize this part of the code (possibly by taking advantage of the fact the list is now sorted and returning the first and last elements). We can then rinse and repeat this process until we have eliminated as many bottlenecks as possible. Calls by Web Request Another feature that was added recently is the ability to view .NET methods grouped by the HTTP requests that caused them to run. This can be helpful in determining which pages, web services, etc. are causing hot spots in your web applications. Summary If you like the other ANTS tools, you’ll like the ANTS Performance Profiler as well. It is extremely easy to use with very little product knowledge required to get up and running. There are profilers built into the higher product lines of Visual Studio, of course, which are also powerful and easy to use. But for quickly jumping in and finding hot spots rapidly, Red Gate’s Performance Profiler 7.4 is an excellent choice. Technorati Tags: Influencers,ANTS,Performance Profiler,Profiler

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  • replacing a method of a Moose object at runtime

    - by xxxxxxx
    Hi, is it possible to replace a method of a Moose object at runtime ? By looking at the source code of Class::MOP::Method(which Moose::Meta::Method inherits from) I concluded that by doing $method->{body} = sub{ my stuff } I would be able to replace at runtime a method of an object. I can get the method using $object->meta->find_method_by_name(<method_name>); However.. this didn't quite work out. Is it conceivable to modify methods at runtime ? and what is the way to do it with Moose ? Thanks

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  • Silverlight WCF method calls fails if WCF service is not running initially

    - by Craig
    Quite simply I have a generic Silverlight 3.0 web page that is calling a Ping method on a WCF service. I do not have the WCF service running initially when I navigate to this Silverlight page. As expected I get a communication exception when I press the Silverlight button to call the Ping method, which I catch. Now if I start the WCF service and press the Ping button I still get the communication exception. How come? The other scenario is the WCF is running when I navigate to the SL page and the Ping method call works. I turn off the WCF service, ping method fails. Turn it back on and the ping method succeeds. How come if it's not running initially the ping method fails always? I could include some sample code if you'd like but this is just a real simple Hello World example using basichttpbinding, straight out the book. Thanks, Craig

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  • Recommended method for XML level loading in XNA

    - by David Saltares Márquez
    I want to use Blender as my level designer tool for an XNA game. Using an existing plugin, I can export my levels to DotScene format which is basically an xml file like this one: <scene formatVersion="1.0.0"> <nodes> <node name="scene-staircase.001"> <position x="10.500000" y="1.400000" z="-9.600000"/> <quaternion x="0.000000" y="0.000000" z="-0.000000" w="1.000000"/> <scale x="1.000000" y="1.000000" z="1.000000"/> <entity name="scene-staircase.001" meshFile="staircase.mesh"/> </node> <node name="Lamp.003"> <position x="11.024290" y="5.903862" z="9.658987"/> <quaternion x="-0.284166" y="0.726942" z="0.342034" w="0.523275"/> <scale x="1.000000" y="1.000000" z="1.000000"/> <light name="Spot.003" type="point"> <colourDiffuse r="0.400000" g="0.154618" b="0.145180"/> <colourSpecular r="0.400000" g="0.154618" b="0.145180"/> <lightAttenuation range="5000.0" constant="1.000000" linear="0.033333" quadratic="0.000000"/> </light> </node> ... </nodes> </scene> Using naming conventions I could easily parse the file and load the correspondent in game content. I am new to XNA and I have seen that there are several methods to load XML files into a game like serializing and deserializing. Which one would you recommend?

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  • Reduce HTTP Requests method for js and css

    - by Giberno
    Is these way can Reduce HTTP Requests? multiple javascript files with & symbol <script type="text/javascript" src="http://yui.yahooapis.com/combo?2.5.2/build/yahoo-dom-event/yahoo-dom-event.js &http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"> </script> multiple css files with @ import <style type="text/css"> @import url(css/style.css); @import url(css/custom.css); </style>

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  • Alternative printing method(s) for an unsupported printer

    - by B. Roland
    Hello! I have in my office, a Konica Minolta bizhub 211 multifunction printer, it works well with windows workstations... It has a lot of good features, like duplex... I haven't found any drivers for UNIX, so I'm looking for alternative methods, how can we make it useable in Ubuntu. I'm thinking on some windows based server, or what I know... I wrote here requesting for drivers: ubuntu.hu, linuxforums.org, forums.debian.net, ubuntuforums.org; and also to the manufacturer, but they said only, that "the first PostScript supported printer is only bizhub 223", so they don't care that thing. Please suggest working methods, Thanks, B. Roland

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  • how do I know when/where to invoke the overridden method of the super class

    - by Henry
    Hi, This question occured to me while programming a Android application, but it seems to be a general programming question more. The situation is, I am extending (subclass-ing) an class from a library, and overriding a method. how do I know if I should invoke the method of super-class? and when? (in the beginning of the overridden method or in the end?) For example, I am overriding the method "public boolean onCreateOptionsMenu(Menu menu)" from class "Activity" in Android platform. And I saw someone write "return super.onCreateOptionsMenu(menu)" in the end of the method, in an example. But how do I know it should be done this way? and it is correct or not? what's the difference if I begin my method with "super.onCreateOptionsMenu(menu)"? BR, Henry

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  • A Method for Reducing Contention and Overhead in Worker Queues for Multithreaded Java Applications

    - by Janice J. Heiss
    A java.net article, rich in practical resources, by IBM India Labs’ Sathiskumar Palaniappan, Kavitha Varadarajan, and Jayashree Viswanathan, explores the challenge of writing code in a way that that effectively makes use of the resources of modern multicore processors and multiprocessor servers.As the article states: “Many server applications, such as Web servers, application servers, database servers, file servers, and mail servers, maintain worker queues and thread pools to handle large numbers of short tasks that arrive from remote sources. In general, a ‘worker queue’ holds all the short tasks that need to be executed, and the threads in the thread pool retrieve the tasks from the worker queue and complete the tasks. Since multiple threads act on the worker queue, adding tasks to and deleting tasks from the worker queue needs to be synchronized, which introduces contention in the worker queue.” The article goes on to explain ways that developers can reduce contention by maintaining one queue per thread. It also demonstrates a work-stealing technique that helps in effectively utilizing the CPU in multicore systems. Read the rest of the article here.

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  • Command line method to find disk usage of camera mounted using gvfs

    - by Hamish Downer
    When my camera was mounted on /media I could use the standard tools (df) to see the disk usage of the card in my camera. However now the camera is mounted using gvfs, and df seems to ignore it. I've also tried pydf and discus to no avail. The camera is definitely available through nautilus, and when I select the camera in nautlius, the status bar tells me the amount of disk free. I can also open the ~/.gvfs/ folder in nautilus and right click on the camera folder and get the disk usage in a graphical way. But that is no use for a script. Are there command line tools that are the equivalent of df for gvfs filesystems? Or even better, a way to make df report on gvfs filesystems?

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  • Meaningful concise method naming guidelines

    - by Sam
    Recently I started releasing an open source project, while I was the only user of the library I did not care about the names, but know I want to assign clever names to each methods to make it easier to learn, but I also need to use concise names so they are easy to write as well. I was thinking about some guidelines about the naming, I am aware of lots of guidelines that only care about letters casing or some simple notes. Here, I am looking after guidelines for meaningful concise naming. For example, this could be part of the guidelines I am looking after: Use Add when an existing item is going to be added to a target, Use Create when a new item is being created and added to a target. Use Remove when an existing item is going to be removed from a target, Use delete when an item is going to be removed permanently. Pair AddXXX methods with RemoveXXX and Pair CreateXXX methods with DeleteXXX methods, but do not mix them. The above guidance may be intuitive for native English speakers, but for me that English is my second language I need to be told about things like this.

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  • Best method to organize/manage dependencies in the VCS within a large solution

    - by SnOrfus
    A simple scenario: 2 projects are in version control The application The test(s) A significant number of checkins are made to the application daily. CI builds and runs all of the automation nightly. In order to write and/or run tests you need to have built the application (to reference/load instrumented assemblies). Now, consider the application to be massive, such that building it is prohibitive in time (an entire day to compile). The obvious side effect here, is that once you've performed a build locally, it is immediately inconsistent with latest. For instance: If I were to sync with latest, and open up one of the test projects, it would not locally build until I built the application. This is the same when syncing to another branch/build/tag. So, in order to even start working, I need to wait a day to build the application locally, so that the assemblies could be loaded - and then those assemblies wouldn't be latest. How do you organize the repository or (ideally) your development environment such that you can continually develop tests against whatever the current build is, or a given specific build, while minimizing building the application as much as possible?

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