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• what will be alternative of pthread_setcanceltype in windows thread programing in c++?

  - by user323422

  what will be alternative of pthread_setcanceltype in windows thread programing in c++?

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• Java Daemon Threading with JNI

  - by gwin003

  I have a Java applet that creates a new non-daemon thread like so: Thread childThread = new Thread(new MyRunnable(_this)); childThread.setDaemon(false); childThread.start(); Then my MyRunnable object calls a native method that is implemented in C++: @Override public void run() { while (true) { if (!ran) { System.out.println("isDaemon: " + Thread.currentThread().isDaemon()); _applet.invokePrintManager(_applet.fFormType, _applet.fFormName, _applet.fPrintImmediately, _applet.fDataSet); ran = true; } } } This C++ method calls into a C# DLL that shows a form. My problem is, whenever the user navigates away from the page with a Java applet on it, JVM (and my C# form) is killed. I need the form and JVM to remain open until it is closed by the user. I tried setting my thread to be a non-daemon thread, which is working because System.out.println("isDaemon: " + Thread.currentThread().isDaemon() prints isDaemon: false. Is there something related to the way that the C# form is created (is there another thread I'm not accounting for) or something I am overlooking?? My thread is not a daemon thread, but the JVM is being killed anyways.

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• Application that provides unique keys to multiple threads

  - by poly

  Thanks all for your help before. So, this is what I came up with so far, the requirements are, application has two or more threads and each thread requires a unique session/transaction ID. is the below considered thread safe? thread 1 will register itself with get_id by sending it's pid thread 2 will do the same then thread 1 & 2 will call the function to get a unique ID function get_id(bool choice/*register thread or get id*/, pid_t pid) { static int pid[15][1]={0};//not sure if this work, anyway considor any it's been set to 0 by any other way than this static int total_threads = 0; static int i = 0; int x=0,y=0; if (choice) // thread registeration part { for(x=0;x<15;x++) { if (pid[x][0]==0); { pid[x][0] = (int) pid; pid[x][1] = (x & pidx[x][1]) << 24;//initiate counter for this PID by shifting x to the 25th bit, it could be any other bit, it's just to set a range. //so the range will be between 0x0000000 and 0x0ffffff, the second one will be 0x1000000 and 0x1ffffff, break; } total_threads++; } } //search if pid exist or not, if yes return transaction id for(x=0;x<15;x++) { if (pid[x][0]==pid); { pid[x][1]++;//put some test here to reset the number to 0 if it reaches 0x0ffffff return pid[x][1]; break; } } }

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• Parallelism in .NET – Part 16, Creating Tasks via a TaskFactory

  - by Reed

  The Task class in the Task Parallel Library supplies a large set of features.  However, when creating the task, and assigning it to a TaskScheduler, and starting the Task, there are quite a few steps involved.  This gets even more cumbersome when multiple tasks are involved.  Each task must be constructed, duplicating any options required, then started individually, potentially on a specific scheduler.  At first glance, this makes the new Task class seem like more work than ThreadPool.QueueUserWorkItem in .NET 3.5. In order to simplify this process, and make Tasks simple to use in simple cases, without sacrificing their power and flexibility, the Task Parallel Library added a new class: TaskFactory. The TaskFactory class is intended to “Provide support for creating and scheduling Task objects.”  Its entire purpose is to simplify development when working with Task instances.  The Task class provides access to the default TaskFactory via the Task.Factory static property.  By default, TaskFactory uses the default TaskScheduler to schedule tasks on a ThreadPool thread.  By using Task.Factory, we can automatically create and start a task in a single “fire and forget” manner, similar to how we did with ThreadPool.QueueUserWorkItem: Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This provides us with the same level of simplicity we had with ThreadPool.QueueUserWorkItem, but even more power.  For example, we can now easily wait on the task: // Start our task on a background thread var task = Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); // Do other work on the main thread, // while the task above executes in the background this.ExecuteWorkSynchronously(); // Wait for the background task to finish task.Wait(); TaskFactory simplifies creation and startup of simple background tasks dramatically. In addition to using the default TaskFactory, it’s often useful to construct a custom TaskFactory.  The TaskFactory class includes an entire set of constructors which allow you to specify the default configuration for every Task instance created by that factory.  This is particularly useful when using a custom TaskScheduler.  For example, look at the sample code for starting a task on the UI thread in Part 15: // Given the following, constructed on the UI thread // TaskScheduler uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // When inside a background task, we can do string status = GetUpdatedStatus(); (new Task(() => { statusLabel.Text = status; })) .Start(uiScheduler); This is actually quite a bit more complicated than necessary.  When we create the uiScheduler instance, we can use that to construct a TaskFactory that will automatically schedule tasks on the UI thread.  To do that, we’d create the following on our main thread, prior to constructing our background tasks: // Construct a task scheduler from the current SynchronizationContext (UI thread) var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // Construct a new TaskFactory using our UI scheduler var uiTaskFactory = new TaskFactory(uiScheduler); If we do this, when we’re on a background thread, we can use this new TaskFactory to marshal a Task back onto the UI thread.  Our previous code simplifies to: // When inside a background task, we can do string status = GetUpdatedStatus(); // Update our UI uiTaskFactory.StartNew( () => statusLabel.Text = status); Notice how much simpler this becomes!  By taking advantage of the convenience provided by a custom TaskFactory, we can now marshal to set data on the UI thread in a single, clear line of code!

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• Simple MPEG Video Stream player, cross-platform, in java, via NetBeans + Swing?

  - by DanM

  Hello all, Trying to build a very simple video player component in a JPanel (or something similar) to sit in a swing app, connect to an mpeg (or, really, anything VLC can output) video stream, and play it. Don't need any controls or anything -- just a live connection to the video stream. It has to be cross-platform -- at least Mac and Windows (linux would be a nice bonus, but not necessary). I'm developing in NetBeans, so any specifics regarding that would be extra-helpful. JMF? Xuggler? Help! Thanks.

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• Easy way to parse a url in C++ cross platform?

  - by Andrew Bucknell

  I need to parse a url to get the protocol host path and query in an application I am writing in c++. The application is intended to be cross platform. Im surprised I cant find anything that does this in boost or poco libraries. Is it somewhere obvious Im not looking? Any suggestions on appropriate open source libs? Or is this something I just have to do my self? Its not super complicated but it seems such a common task I am surprised there isnt a common solution.

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• Requesting a website by client side script = Cross Side Scripting Hack. But requesting a website by

  - by 1s2a3n4j5e6e7v

  Generally, when we want to show the contents of some web page in the same page, we go for ajax requests. If say, I request to a web page in different domain with AJAX, it is not allowed because of the Cross side scripting error. But why is it allowed to access via a server side page. For e.g. we can use CURL in php to access any site.? Why is this feature OK for server side scripting and NOT OK for Client Side Scripting?

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• Can I using cross-site XmlHttpRequest in Itunes LP environment?

  - by jameulrich

  Itunes is based on Webkit platform and we can't use cross-site XmlHttpRequest in JavaScript because of security policy. But, as a exception, we can do that with a special header. Here is source code and I did it successfully in Safari: /////////////// var url = 'http://mysite.net/canvas.php'; var mybody = "Arun"; var http = new XMLHttpRequest(); http.open("POST", url, true); http.setRequestHeader("X-PINGOTHER", "pingpong"); http.setRequestHeader('Content-Type', 'application/xml'); http.setRequestHeader("Content-length", mybody.length); http.setRequestHeader("Connection", "close"); http.send(mybody); /////////////// I sent xml data to my server and get return response successfully in Safari browser but i can't do it in iTunes LP environment. So what is the problems?

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• How to make a cross browser, W3C valid, semantic, non-javascript ROUND corner?

  - by jitendra

  I want to make a cross-browser (FF3, IE6, Safari, Opera), W3C valid (HTML and CSS both), stretchable (horizontally vertically), without JavaScript and with Semantic and lesser HTML markup Round CORNER. Images can be used for IE6. I've tried and tested many techniques available on community. But everything has one of the problems mentioned above . If anyone knows what I want please share with me? Remember I want to make it without any type of JavaScript, jquery or any type of js.

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• what is the best and valid way for cross browser min-height?

  - by metal-gear-solid

  for #main-content I don't want to give any fix height because content can be long and short but if content is short then it should take minimum height 500px. i need compatibility in all browser. Is thery any w3c valid and cross browser way without using !important because i read !important should not be used In conclusion, don’t use the !important declaration unless you’ve tried everything else first, and keep in mind any drawbacks. If you do use it, it would probably make sense, if possible, to put a comment in your CSS next to any styles that are being overridden, to ensure better code maintainability. I tried to cover everything significant in relation to use of the !important declaration, so please offer comments if you think there’s anything I’ve missed, or if I’ve misstated anything, and I’ll be happy to make any needed corrections. http://www.impressivewebs.com/everything-you-need-to-know-about-the-important-css-declaration/

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• Java FMJ is not cross platfrom ? How can it be fixed ?

  - by Stackfan

  I was trying to use FMJ (for windows/linux/mac). Where JMF was not working for me (so decided to work with FMJ as it is cross platfaorm). But when ever i am trying FMJ it never works, where you can see the difference in the screen shot. ex: http://i.imgur.com/AjcJh.png Thanks & Regards Note: I have two camera connected in the same PC and Flash detects always both of them without any issue. But FMJ is never working ?????.

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• How to figure out how much RAM each prefork thread requires for maximum Wordpress performance on an EC2 small instance

  - by two7s_clash

  Just read Making WordPress Stable on EC2-Micro In the "Tuning Apache" section, I can't quite figure out how he comes up with his numbers for his prefork config. He explains how to get the numbers for an average process, which I get. But then: Or roughly 53MB per process...In this case, ten threads should be safe. This means that if we receive more than ten simultaneous requests, the other requests will be queued until a worker thread is available. In order to maximize performance, we will also configure the system to have this number of threads available all of the time. From 53MB per process, with 613MB of RAM, he somehow gets this config, which I don't get: <IfModule prefork.c> StartServers 10 MinSpareServers 10 MaxSpareServers 10 MaxClients 10 MaxRequestsPerChild 4000 </IfModule> How exactly does he get this from 53MB per process, with 613MB limit? Bonus question From the below, on a small instance (1.7 GB memory), what would good settings be? bitnami@ip-10-203-39-166:~$ ps xav |grep httpd 1411 ? Ss 0:00 2 0 114928 15436 0.8 /opt/bitnami/apache2/bin/httpd -f /opt/bitnami/apache2/conf/httpd.conf 1415 ? S 0:06 10 0 125860 55900 3.1 /opt/bitnami/apache2/bin/httpd -f /opt/bitnami/apache2/conf/httpd.conf 1426 ? S 0:08 19 0 127000 62996 3.5 /opt/bitnami/apache2/bin/httpd -f /opt/bitnami/apache2/conf/httpd.conf 1446 ? S 0:05 48 0 131932 72792 4.1 /opt/bitnami/apache2/bin/httpd -f /opt/bitnami/apache2/conf/httpd.conf 1513 ? S 0:05 7 0 125672 54840 3.1 /opt/bitnami/apache2/bin/httpd -f /opt/bitnami/apache2/conf/httpd.conf 1516 ? S 0:02 2 0 125228 48680 2.7 /opt/bitnami/apache2/bin/httpd -f /opt/bitnami/apache2/conf/httpd.conf 1517 ? S 0:06 2 0 127004 55796 3.1 /opt/bitnami/apache2/bin/httpd -f /opt/bitnami/apache2/conf/httpd.conf 1518 ? S 0:03 1 0 127196 54208 3.0 /opt/bitnami/apache2/bin/httpd -f /opt/bitnami/apache2/conf/httpd.conf 1531 ? R 0:04 0 0 127500 54236 3.0 /opt/bitnami/apache2/bin/httpd -f /opt/bitnami/apache2/conf/httpd.conf

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• super function doesn't work inside a maya python module

  - by sfjedi

  Somehow, this works fine in the Maya/Python script editor, but fails when it's inside of my module code. Anyone have any ideas? class ControlShape(object): def __init__(self, *args, **kwargs): print 'Inside ControlShape...' class Cross(ControlShape): def __init__(self, *args, **kwargs): print 'Entering Cross...' super(Cross, self).__init__(*args, **kwargs) print 'Leaving Cross...' x = Cross() This gives me a TypeError: super(type, obj): obj must be an instance or subtype of type.

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• Security Issues with Single Page Apps

  - by Stephen.Walther

  Last week, I was asked to do a code review of a Single Page App built using the ASP.NET Web API, Durandal, and Knockout (good stuff!). In particular, I was asked to investigate whether there any special security issues associated with building a Single Page App which are not present in the case of a traditional server-side ASP.NET application. In this blog entry, I discuss two areas in which you need to exercise extra caution when building a Single Page App. I discuss how Single Page Apps are extra vulnerable to both Cross-Site Scripting (XSS) attacks and Cross-Site Request Forgery (CSRF) attacks. This goal of this blog post is NOT to persuade you to avoid writing Single Page Apps. I’m a big fan of Single Page Apps. Instead, the goal is to ensure that you are fully aware of some of the security issues related to Single Page Apps and ensure that you know how to guard against them. Cross-Site Scripting (XSS) Attacks According to WhiteHat Security, over 65% of public websites are open to XSS attacks. That’s bad. By taking advantage of XSS holes in a website, a hacker can steal your credit cards, passwords, or bank account information. Any website that redisplays untrusted information is open to XSS attacks. Let me give you a simple example. Imagine that you want to display the name of the current user on a page. To do this, you create the following server-side ASP.NET page located at http://MajorBank.com/SomePage.aspx: <%@Page Language="C#" %> <html> <head> <title>Some Page</title> </head> <body> Welcome <%= Request["username"] %> </body> </html> Nothing fancy here. Notice that the page displays the current username by using Request[“username”]. Using Request[“username”] displays the username regardless of whether the username is present in a cookie, a form field, or a query string variable. Unfortunately, by using Request[“username”] to redisplay untrusted information, you have now opened your website to XSS attacks. Here’s how. Imagine that an evil hacker creates the following link on another website (hackers.com): <a href="/SomePage.aspx?username=<script src=Evil.js></script>">Visit MajorBank</a> Notice that the link includes a query string variable named username and the value of the username variable is an HTML <SCRIPT> tag which points to a JavaScript file named Evil.js. When anyone clicks on the link, the <SCRIPT> tag will be injected into SomePage.aspx and the Evil.js script will be loaded and executed. What can a hacker do in the Evil.js script? Anything the hacker wants. For example, the hacker could display a popup dialog on the MajorBank.com site which asks the user to enter their password. The script could then post the password back to hackers.com and now the evil hacker has your secret password. ASP.NET Web Forms and ASP.NET MVC have two automatic safeguards against this type of attack: Request Validation and Automatic HTML Encoding. Protecting Coming In (Request Validation) In a server-side ASP.NET app, you are protected against the XSS attack described above by a feature named Request Validation. If you attempt to submit “potentially dangerous” content — such as a JavaScript <SCRIPT> tag — in a form field or query string variable then you get an exception. Unfortunately, Request Validation only applies to server-side apps. Request Validation does not help in the case of a Single Page App. In particular, the ASP.NET Web API does not pay attention to Request Validation. You can post any content you want – including <SCRIPT> tags – to an ASP.NET Web API action. For example, the following HTML page contains a form. When you submit the form, the form data is submitted to an ASP.NET Web API controller on the server using an Ajax request: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title></title> </head> <body> <form data-bind="submit:submit"> <div> <label> User Name: <input data-bind="value:user.userName" /> </label> </div> <div> <label> Email: <input data-bind="value:user.email" /> </label> </div> <div> <input type="submit" value="Submit" /> </div> </form> <script src="Scripts/jquery-1.7.1.js"></script> <script src="Scripts/knockout-2.1.0.js"></script> <script> var viewModel = { user: { userName: ko.observable(), email: ko.observable() }, submit: function () { $.post("/api/users", ko.toJS(this.user)); } }; ko.applyBindings(viewModel); </script> </body> </html> The form above is using Knockout to bind the form fields to a view model. When you submit the form, the view model is submitted to an ASP.NET Web API action on the server. Here’s the server-side ASP.NET Web API controller and model class: public class UsersController : ApiController { public HttpResponseMessage Post(UserViewModel user) { var userName = user.UserName; return Request.CreateResponse(HttpStatusCode.OK); } } public class UserViewModel { public string UserName { get; set; } public string Email { get; set; } } If you submit the HTML form, you don’t get an error. The “potentially dangerous” content is passed to the server without any exception being thrown. In the screenshot below, you can see that I was able to post a username form field with the value “<script>alert(‘boo’)</script”. So what this means is that you do not get automatic Request Validation in the case of a Single Page App. You need to be extra careful in a Single Page App about ensuring that you do not display untrusted content because you don’t have the Request Validation safety net which you have in a traditional server-side ASP.NET app. Protecting Going Out (Automatic HTML Encoding) Server-side ASP.NET also protects you from XSS attacks when you render content. By default, all content rendered by the razor view engine is HTML encoded. For example, the following razor view displays the text “<b>Hello!</b>” instead of the text “Hello!” in bold: @{ var message = "<b>Hello!</b>"; } @message   If you don’t want to render content as HTML encoded in razor then you need to take the extra step of using the @Html.Raw() helper. In a Web Form page, if you use <%: %> instead of <%= %> then you get automatic HTML Encoding: <%@ Page Language="C#" %> <% var message = "<b>Hello!</b>"; %> <%: message %> This automatic HTML Encoding will prevent many types of XSS attacks. It prevents <script> tags from being rendered and only allows &lt;script&gt; tags to be rendered which are useless for executing JavaScript. (This automatic HTML encoding does not protect you from all forms of XSS attacks. For example, you can assign the value “javascript:alert(‘evil’)” to the Hyperlink control’s NavigateUrl property and execute the JavaScript). The situation with Knockout is more complicated. If you use the Knockout TEXT binding then you get HTML encoded content. On the other hand, if you use the HTML binding then you do not: <!-- This JavaScript DOES NOT execute --> <div data-bind="text:someProp"></div> <!-- This Javacript DOES execute --> <div data-bind="html:someProp"></div> <script src="Scripts/jquery-1.7.1.js"></script> <script src="Scripts/knockout-2.1.0.js"></script> <script> var viewModel = { someProp : "<script>alert('Evil!')<" + "/script>" }; ko.applyBindings(viewModel); </script>   So, in the page above, the DIV element which uses the TEXT binding is safe from XSS attacks. According to the Knockout documentation: “Since this binding sets your text value using a text node, it’s safe to set any string value without risking HTML or script injection.” Just like server-side HTML encoding, Knockout does not protect you from all types of XSS attacks. For example, there is nothing in Knockout which prevents you from binding JavaScript to a hyperlink like this: <a data-bind="attr:{href:homePageUrl}">Go</a> <script src="Scripts/jquery-1.7.1.min.js"></script> <script src="Scripts/knockout-2.1.0.js"></script> <script> var viewModel = { homePageUrl: "javascript:alert('evil!')" }; ko.applyBindings(viewModel); </script> In the page above, the value “javascript:alert(‘evil’)” is bound to the HREF attribute using Knockout. When you click the link, the JavaScript executes. Cross-Site Request Forgery (CSRF) Attacks Cross-Site Request Forgery (CSRF) attacks rely on the fact that a session cookie does not expire until you close your browser. In particular, if you visit and login to MajorBank.com and then you navigate to Hackers.com then you will still be authenticated against MajorBank.com even after you navigate to Hackers.com. Because MajorBank.com cannot tell whether a request is coming from MajorBank.com or Hackers.com, Hackers.com can submit requests to MajorBank.com pretending to be you. For example, Hackers.com can post an HTML form from Hackers.com to MajorBank.com and change your email address at MajorBank.com. Hackers.com can post a form to MajorBank.com using your authentication cookie. After your email address has been changed, by using a password reset page at MajorBank.com, a hacker can access your bank account. To prevent CSRF attacks, you need some mechanism for detecting whether a request is coming from a page loaded from your website or whether the request is coming from some other website. The recommended way of preventing Cross-Site Request Forgery attacks is to use the “Synchronizer Token Pattern” as described here: https://www.owasp.org/index.php/Cross-Site_Request_Forgery_%28CSRF%29_Prevention_Cheat_Sheet When using the Synchronizer Token Pattern, you include a hidden input field which contains a random token whenever you display an HTML form. When the user opens the form, you add a cookie to the user’s browser with the same random token. When the user posts the form, you verify that the hidden form token and the cookie token match. Preventing Cross-Site Request Forgery Attacks with ASP.NET MVC ASP.NET gives you a helper and an action filter which you can use to thwart Cross-Site Request Forgery attacks. For example, the following razor form for creating a product shows how you use the @Html.AntiForgeryToken() helper: @model MvcApplication2.Models.Product <h2>Create Product</h2> @using (Html.BeginForm()) { @Html.AntiForgeryToken(); <div> @Html.LabelFor( p => p.Name, "Product Name:") @Html.TextBoxFor( p => p.Name) </div> <div> @Html.LabelFor( p => p.Price, "Product Price:") @Html.TextBoxFor( p => p.Price) </div> <input type="submit" /> } The @Html.AntiForgeryToken() helper generates a random token and assigns a serialized version of the same random token to both a cookie and a hidden form field. (Actually, if you dive into the source code, the AntiForgeryToken() does something a little more complex because it takes advantage of a user’s identity when generating the token). Here’s what the hidden form field looks like: <input name=”__RequestVerificationToken” type=”hidden” value=”NqqZGAmlDHh6fPTNR_mti3nYGUDgpIkCiJHnEEL59S7FNToyyeSo7v4AfzF2i67Cv0qTB1TgmZcqiVtgdkW2NnXgEcBc-iBts0x6WAIShtM1″ /> And here’s what the cookie looks like using the Google Chrome developer toolbar: You use the [ValidateAntiForgeryToken] action filter on the controller action which is the recipient of the form post to validate that the token in the hidden form field matches the token in the cookie. If the tokens don’t match then validation fails and you can’t post the form: public ActionResult Create() { return View(); } [ValidateAntiForgeryToken] [HttpPost] public ActionResult Create(Product productToCreate) { if (ModelState.IsValid) { // save product to db return RedirectToAction("Index"); } return View(); } How does this all work? Let’s imagine that a hacker has copied the Create Product page from MajorBank.com to Hackers.com – the hacker grabs the HTML source and places it at Hackers.com. Now, imagine that the hacker trick you into submitting the Create Product form from Hackers.com to MajorBank.com. You’ll get the following exception: The Cross-Site Request Forgery attack is blocked because the anti-forgery token included in the Create Product form at Hackers.com won’t match the anti-forgery token stored in the cookie in your browser. The tokens were generated at different times for different users so the attack fails. Preventing Cross-Site Request Forgery Attacks with a Single Page App In a Single Page App, you can’t prevent Cross-Site Request Forgery attacks using the same method as a server-side ASP.NET MVC app. In a Single Page App, HTML forms are not generated on the server. Instead, in a Single Page App, forms are loaded dynamically in the browser. Phil Haack has a blog post on this topic where he discusses passing the anti-forgery token in an Ajax header instead of a hidden form field. He also describes how you can create a custom anti-forgery token attribute to compare the token in the Ajax header and the token in the cookie. See: http://haacked.com/archive/2011/10/10/preventing-csrf-with-ajax.aspx Also, take a look at Johan’s update to Phil Haack’s original post: http://johan.driessen.se/posts/Updated-Anti-XSRF-Validation-for-ASP.NET-MVC-4-RC (Other server frameworks such as Rails and Django do something similar. For example, Rails uses an X-CSRF-Token to prevent CSRF attacks which you generate on the server – see http://excid3.com/blog/rails-tip-2-include-csrf-token-with-every-ajax-request/#.UTFtgDDkvL8 ). For example, if you are creating a Durandal app, then you can use the following razor view for your one and only server-side page: @{ Layout = null; } <!DOCTYPE html> <html> <head> <title>Index</title> </head> <body> @Html.AntiForgeryToken() <div id="applicationHost"> Loading app.... </div> @Scripts.Render("~/scripts/vendor") <script type="text/javascript" src="~/App/durandal/amd/require.js" data-main="/App/main"></script> </body> </html> Notice that this page includes a call to @Html.AntiForgeryToken() to generate the anti-forgery token. Then, whenever you make an Ajax request in the Durandal app, you can retrieve the anti-forgery token from the razor view and pass the token as a header: var csrfToken = $("input[name='__RequestVerificationToken']").val(); $.ajax({ headers: { __RequestVerificationToken: csrfToken }, type: "POST", dataType: "json", contentType: 'application/json; charset=utf-8', url: "/api/products", data: JSON.stringify({ name: "Milk", price: 2.33 }), statusCode: { 200: function () { alert("Success!"); } } }); Use the following code to create an action filter which you can use to match the header and cookie tokens: using System.Linq; using System.Net.Http; using System.Web.Helpers; using System.Web.Http.Controllers; namespace MvcApplication2.Infrastructure { public class ValidateAjaxAntiForgeryToken : System.Web.Http.AuthorizeAttribute { protected override bool IsAuthorized(HttpActionContext actionContext) { var headerToken = actionContext .Request .Headers .GetValues("__RequestVerificationToken") .FirstOrDefault(); ; var cookieToken = actionContext .Request .Headers .GetCookies() .Select(c => c[AntiForgeryConfig.CookieName]) .FirstOrDefault(); // check for missing cookie or header if (cookieToken == null || headerToken == null) { return false; } // ensure that the cookie matches the header try { AntiForgery.Validate(cookieToken.Value, headerToken); } catch { return false; } return base.IsAuthorized(actionContext); } } } Notice that the action filter derives from the base AuthorizeAttribute. The ValidateAjaxAntiForgeryToken only works when the user is authenticated and it will not work for anonymous requests. Add the action filter to your ASP.NET Web API controller actions like this: [ValidateAjaxAntiForgeryToken] public HttpResponseMessage PostProduct(Product productToCreate) { // add product to db return Request.CreateResponse(HttpStatusCode.OK); } After you complete these steps, it won’t be possible for a hacker to pretend to be you at Hackers.com and submit a form to MajorBank.com. The header token used in the Ajax request won’t travel to Hackers.com. This approach works, but I am not entirely happy with it. The one thing that I don’t like about this approach is that it creates a hard dependency on using razor. Your single page in your Single Page App must be generated from a server-side razor view. A better solution would be to generate the anti-forgery token in JavaScript. Unfortunately, until all browsers support a way to generate cryptographically strong random numbers – for example, by supporting the window.crypto.getRandomValues() method — there is no good way to generate anti-forgery tokens in JavaScript. So, at least right now, the best solution for generating the tokens is the server-side solution with the (regrettable) dependency on razor. Conclusion The goal of this blog entry was to explore some ways in which you need to handle security differently in the case of a Single Page App than in the case of a traditional server app. In particular, I focused on how to prevent Cross-Site Scripting and Cross-Site Request Forgery attacks in the case of a Single Page App. I want to emphasize that I am not suggesting that Single Page Apps are inherently less secure than server-side apps. Whatever type of web application you build – regardless of whether it is a Single Page App, an ASP.NET MVC app, an ASP.NET Web Forms app, or a Rails app – you must constantly guard against security vulnerabilities.

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• C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

  - by James Michael Hare

  Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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• Win7 Bluescreen: IRQ_NOT_LESS_OR_EQUAL | athrxusb.sys

  - by wretrOvian

  Hi I'd left my system on last night, and found the bluescreen in the morning. This has been happening occasionally, over the past few days. Details: ================================================== Dump File : 022710-18236-01.dmp Crash Time : 2/27/2010 8:46:44 AM Bug Check String : DRIVER_IRQL_NOT_LESS_OR_EQUAL Bug Check Code : 0x000000d1 Parameter 1 : 00000000`00001001 Parameter 2 : 00000000`00000002 Parameter 3 : 00000000`00000000 Parameter 4 : fffff880`06b5c0e1 Caused By Driver : athrxusb.sys Caused By Address : athrxusb.sys+760e1 File Description : Product Name : Company : File Version : Processor : x64 Computer Name : Full Path : C:\Windows\minidump\022710-18236-01.dmp Processors Count : 2 Major Version : 15 Minor Version : 7600 ================================================== HiJackThis ("[...]" indicates removed text; full log posted to pastebin): Logfile of Trend Micro HijackThis v2.0.2 Scan saved at 8:49:15 AM, on 2/27/2010 Platform: Unknown Windows (WinNT 6.01.3504) MSIE: Internet Explorer v8.00 (8.00.7600.16385) Boot mode: Normal Running processes: C:\Windows\DAODx.exe C:\Program Files (x86)\ASUS\EPU\EPU.exe C:\Program Files\ASUS\TurboV\TurboV.exe C:\Program Files (x86)\PowerISO\PWRISOVM.EXE C:\Program Files (x86)\OpenOffice.org 3\program\soffice.exe C:\Program Files (x86)\OpenOffice.org 3\program\soffice.bin D:\Downloads\HijackThis.exe C:\Program Files (x86)\uTorrent\uTorrent.exe R1 - HKCU\Software\Microsoft\Internet Explorer\[...] [...] O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files (x86)\Java\jre6\bin\jp2ssv.dll O4 - HKLM\..\Run: [HDAudDeck] C:\Program Files (x86)\VIA\VIAudioi\VDeck\VDeck.exe -r O4 - HKLM\..\Run: [StartCCC] "C:\Program Files (x86)\ATI Technologies\ATI.ACE\Core-Static\CLIStart.exe" MSRun O4 - HKLM\..\Run: [TurboV] "C:\Program Files\ASUS\TurboV\TurboV.exe" O4 - HKLM\..\Run: [PWRISOVM.EXE] C:\Program Files (x86)\PowerISO\PWRISOVM.EXE O4 - HKLM\..\Run: [googletalk] C:\Program Files (x86)\Google\Google Talk\googletalk.exe /autostart O4 - HKLM\..\Run: [AdobeCS4ServiceManager] "C:\Program Files (x86)\Common Files\Adobe\CS4ServiceManager\CS4ServiceManager.exe" -launchedbylogin O4 - HKCU\..\Run: [uTorrent] "C:\Program Files (x86)\uTorrent\uTorrent.exe" O4 - HKUS\S-1-5-19\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User 'LOCAL SERVICE') O4 - HKUS\S-1-5-19\..\RunOnce: [mctadmin] C:\Windows\System32\mctadmin.exe (User 'LOCAL SERVICE') O4 - HKUS\S-1-5-20\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User 'NETWORK SERVICE') O4 - HKUS\S-1-5-20\..\RunOnce: [mctadmin] C:\Windows\System32\mctadmin.exe (User 'NETWORK SERVICE') O4 - Startup: OpenOffice.org 3.1.lnk = C:\Program Files (x86)\OpenOffice.org 3\program\quickstart.exe O13 - Gopher Prefix: O23 - Service: @%SystemRoot%\system32\Alg.exe,-112 (ALG) - Unknown owner - C:\Windows\System32\alg.exe (file missing) O23 - Service: AMD External Events Utility - Unknown owner - C:\Windows\system32\atiesrxx.exe (file missing) O23 - Service: ASUS System Control Service (AsSysCtrlService) - Unknown owner - C:\Program Files (x86)\ASUS\AsSysCtrlService\1.00.02\AsSysCtrlService.exe O23 - Service: DeviceVM Meta Data Export Service (DvmMDES) - DeviceVM - C:\ASUS.SYS\config\DVMExportService.exe O23 - Service: @%SystemRoot%\system32\efssvc.dll,-100 (EFS) - Unknown owner - C:\Windows\System32\lsass.exe (file missing) O23 - Service: ESET HTTP Server (EhttpSrv) - ESET - C:\Program Files\ESET\ESET NOD32 Antivirus\EHttpSrv.exe O23 - Service: ESET Service (ekrn) - ESET - C:\Program Files\ESET\ESET NOD32 Antivirus\x86\ekrn.exe O23 - Service: @%systemroot%\system32\fxsresm.dll,-118 (Fax) - Unknown owner - C:\Windows\system32\fxssvc.exe (file missing) O23 - Service: FLEXnet Licensing Service - Acresso Software Inc. - C:\Program Files (x86)\Common Files\Macrovision Shared\FLEXnet Publisher\FNPLicensingService.exe O23 - Service: FLEXnet Licensing Service 64 - Acresso Software Inc. - C:\Program Files\Common Files\Macrovision Shared\FLEXnet Publisher\FNPLicensingService64.exe O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files (x86)\Common Files\InstallShield\Driver\11\Intel 32\IDriverT.exe O23 - Service: @keyiso.dll,-100 (KeyIso) - Unknown owner - C:\Windows\system32\lsass.exe (file missing) O23 - Service: @comres.dll,-2797 (MSDTC) - Unknown owner - C:\Windows\System32\msdtc.exe (file missing) O23 - Service: @%SystemRoot%\System32\netlogon.dll,-102 (Netlogon) - Unknown owner - C:\Windows\system32\lsass.exe (file missing) O23 - Service: @%systemroot%\system32\psbase.dll,-300 (ProtectedStorage) - Unknown owner - C:\Windows\system32\lsass.exe (file missing) O23 - Service: Protexis Licensing V2 (PSI_SVC_2) - Protexis Inc. - c:\Program Files (x86)\Common Files\Protexis\License Service\PsiService_2.exe O23 - Service: @%systemroot%\system32\Locator.exe,-2 (RpcLocator) - Unknown owner - C:\Windows\system32\locator.exe (file missing) O23 - Service: @%SystemRoot%\system32\samsrv.dll,-1 (SamSs) - Unknown owner - C:\Windows\system32\lsass.exe (file missing) O23 - Service: @%SystemRoot%\system32\snmptrap.exe,-3 (SNMPTRAP) - Unknown owner - C:\Windows\System32\snmptrap.exe (file missing) O23 - Service: @%systemroot%\system32\spoolsv.exe,-1 (Spooler) - Unknown owner - C:\Windows\System32\spoolsv.exe (file missing) O23 - Service: @%SystemRoot%\system32\sppsvc.exe,-101 (sppsvc) - Unknown owner - C:\Windows\system32\sppsvc.exe (file missing) O23 - Service: Steam Client Service - Valve Corporation - C:\Program Files (x86)\Common Files\Steam\SteamService.exe O23 - Service: @%SystemRoot%\system32\ui0detect.exe,-101 (UI0Detect) - Unknown owner - C:\Windows\system32\UI0Detect.exe (file missing) O23 - Service: @%SystemRoot%\system32\vaultsvc.dll,-1003 (VaultSvc) - Unknown owner - C:\Windows\system32\lsass.exe (file missing) O23 - Service: @%SystemRoot%\system32\vds.exe,-100 (vds) - Unknown owner - C:\Windows\System32\vds.exe (file missing) O23 - Service: @%systemroot%\system32\vssvc.exe,-102 (VSS) - Unknown owner - C:\Windows\system32\vssvc.exe (file missing) O23 - Service: @%systemroot%\system32\wbengine.exe,-104 (wbengine) - Unknown owner - C:\Windows\system32\wbengine.exe (file missing) O23 - Service: @%Systemroot%\system32\wbem\wmiapsrv.exe,-110 (wmiApSrv) - Unknown owner - C:\Windows\system32\wbem\WmiApSrv.exe (file missing) O23 - Service: @%PROGRAMFILES%\Windows Media Player\wmpnetwk.exe,-101 (WMPNetworkSvc) - Unknown owner - C:\Program Files (x86)\Windows Media Player\wmpnetwk.exe (file missing) -- End of file - 6800 bytes CPU-Z ("[...]" indicates removed text; see full log posted to pastebin): CPU-Z TXT Report ------------------------------------------------------------------------- Binaries ------------------------------------------------------------------------- CPU-Z version 1.53.1 Processors ------------------------------------------------------------------------- Number of processors 1 Number of threads 2 APICs ------------------------------------------------------------------------- Processor 0 -- Core 0 -- Thread 0 0 -- Core 1 -- Thread 0 1 Processors Information ------------------------------------------------------------------------- Processor 1 ID = 0 Number of cores 2 (max 2) Number of threads 2 (max 2) Name AMD Phenom II X2 550 Codename Callisto Specification AMD Phenom(tm) II X2 550 Processor Package Socket AM3 (938) CPUID F.4.2 Extended CPUID 10.4 Brand ID 29 Core Stepping RB-C2 Technology 45 nm Core Speed 3110.7 MHz Multiplier x FSB 15.5 x 200.7 MHz HT Link speed 2006.9 MHz Instructions sets MMX (+), 3DNow! (+), SSE, SSE2, SSE3, SSE4A, x86-64, AMD-V L1 Data cache 2 x 64 KBytes, 2-way set associative, 64-byte line size L1 Instruction cache 2 x 64 KBytes, 2-way set associative, 64-byte line size L2 cache 2 x 512 KBytes, 16-way set associative, 64-byte line size L3 cache 6 MBytes, 48-way set associative, 64-byte line size FID/VID Control yes Min FID 4.0x P-State FID 0xF - VID 0x10 P-State FID 0x8 - VID 0x18 P-State FID 0x3 - VID 0x20 P-State FID 0x100 - VID 0x2C Package Type 0x1 Model 50 String 1 0x7 String 2 0x6 Page 0x0 TDP Limit 79 Watts TDC Limit 66 Amps Attached device PCI device at bus 0, device 24, function 0 Attached device PCI device at bus 0, device 24, function 1 Attached device PCI device at bus 0, device 24, function 2 Attached device PCI device at bus 0, device 24, function 3 Attached device PCI device at bus 0, device 24, function 4 Thread dumps ------------------------------------------------------------------------- CPU Thread 0 APIC ID 0 Topology Processor ID 0, Core ID 0, Thread ID 0 Type 0200400Ah Max CPUID level 00000005h Max CPUID ext. level 8000001Bh Cache descriptor Level 1, I, 64 KB, 1 thread(s) Cache descriptor Level 1, D, 64 KB, 1 thread(s) Cache descriptor Level 2, U, 512 KB, 1 thread(s) Cache descriptor Level 3, U, 6 MB, 2 thread(s) CPUID 0x00000000 0x00000005 0x68747541 0x444D4163 0x69746E65 0x00000001 0x00100F42 0x00020800 0x00802009 0x178BFBFF 0x00000002 0x00000000 0x00000000 0x00000000 0x00000000 0x00000003 0x00000000 0x00000000 0x00000000 0x00000000 0x00000004 0x00000000 0x00000000 0x00000000 0x00000000 0x00000005 0x00000040 0x00000040 0x00000003 0x00000000 [...] CPU Thread 1 APIC ID 1 Topology Processor ID 0, Core ID 1, Thread ID 0 Type 0200400Ah Max CPUID level 00000005h Max CPUID ext. level 8000001Bh Cache descriptor Level 1, I, 64 KB, 1 thread(s) Cache descriptor Level 1, D, 64 KB, 1 thread(s) Cache descriptor Level 2, U, 512 KB, 1 thread(s) Cache descriptor Level 3, U, 6 MB, 2 thread(s) CPUID 0x00000000 0x00000005 0x68747541 0x444D4163 0x69746E65 0x00000001 0x00100F42 0x01020800 0x00802009 0x178BFBFF 0x00000002 0x00000000 0x00000000 0x00000000 0x00000000 0x00000003 0x00000000 0x00000000 0x00000000 0x00000000 0x00000004 0x00000000 0x00000000 0x00000000 0x00000000 0x00000005 0x00000040 0x00000040 0x00000003 0x00000000 [...] Chipset ------------------------------------------------------------------------- Northbridge AMD 790GX rev. 00 Southbridge ATI SB750 rev. 00 Memory Type DDR3 Memory Size 4096 MBytes Channels Dual, (Unganged) Memory Frequency 669.0 MHz (3:10) CAS# latency (CL) 9.0 RAS# to CAS# delay (tRCD) 9 RAS# Precharge (tRP) 9 Cycle Time (tRAS) 24 Bank Cycle Time (tRC) 33 Command Rate (CR) 1T Uncore Frequency 2006.9 MHz Memory SPD ------------------------------------------------------------------------- DIMM # 1 SMBus address 0x50 Memory type DDR3 Module format UDIMM Manufacturer (ID) G.Skill (7F7F7F7FCD000000) Size 2048 MBytes Max bandwidth PC3-10700 (667 MHz) Part number F3-10600CL9-2GBNT Number of banks 8 Nominal Voltage 1.50 Volts EPP no XMP no JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency JEDEC #1 6.0-6-6-17-23 @ 457 MHz JEDEC #2 7.0-7-7-20-27 @ 533 MHz JEDEC #3 8.0-8-8-22-31 @ 609 MHz JEDEC #4 9.0-9-9-25-34 @ 685 MHz DIMM # 2 SMBus address 0x51 Memory type DDR3 Module format UDIMM Manufacturer (ID) G.Skill (7F7F7F7FCD000000) Size 2048 MBytes Max bandwidth PC3-10700 (667 MHz) Part number F3-10600CL9-2GBNT Number of banks 8 Nominal Voltage 1.50 Volts EPP no XMP no JEDEC timings table CL-tRCD-tRP-tRAS-tRC @ frequency JEDEC #1 6.0-6-6-17-23 @ 457 MHz JEDEC #2 7.0-7-7-20-27 @ 533 MHz JEDEC #3 8.0-8-8-22-31 @ 609 MHz JEDEC #4 9.0-9-9-25-34 @ 685 MHz DIMM # 1 SPD registers [...] DIMM # 2 SPD registers [...] Monitoring ------------------------------------------------------------------------- Mainboard Model M4A78T-E (0x000001F7 - 0x00A955E4) LPCIO ------------------------------------------------------------------------- LPCIO Vendor ITE LPCIO Model IT8720 LPCIO Vendor ID 0x90 LPCIO Chip ID 0x8720 LPCIO Revision ID 0x2 Config Mode I/O address 0x2E Config Mode LDN 0x4 Config Mode registers [...] Register space LPC, base address = 0x0290 Hardware Monitors ------------------------------------------------------------------------- Hardware monitor ITE IT87 Voltage 1 1.62 Volts [0x65] (VIN1) Voltage 2 1.15 Volts [0x48] (CPU VCORE) Voltage 3 5.03 Volts [0xBB] (+5V) Voltage 8 3.34 Volts [0xD1] (VBAT) Temperature 0 39°C (102°F) [0x27] (TMPIN0) Temperature 1 43°C (109°F) [0x2B] (TMPIN1) Fan 0 3096 RPM [0xDA] (FANIN0) Register space LPC, base address = 0x0290 [...] Hardware monitor AMD SB6xx/7xx Voltage 0 1.37 Volts [0x1D2] (CPU VCore) Voltage 1 3.50 Volts [0x27B] (CPU IO) Voltage 2 12.68 Volts [0x282] (+12V) Hardware monitor AMD Phenom II X2 550 Power 0 89.10 W (Processor) Temperature 0 35°C (94°F) [0x115] (Core #0) Temperature 1 35°C (94°F) [0x115] (Core #1)

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• How does cross domain authentication work in a firewalled environment?

  - by LVLAaron

  This is a simplification and the names have been changed to protect the innocent. The assets: Active Directory Domains corp.lan saas.lan User accounts [email protected] [email protected] Servers dc.corp.lan (domain controller) dc.saas.lan (domain controller) server.saas.lan A one way trust exists between the domains so user accounts in corp.lan and log into servers in saas.lan No firewall between dc.corp.lan and dc.saas.lan server.saas.lan is in a firewalled zone and a set of rules exist so it can talk to dc.saas.lan I can log into server.saas.lan with [email protected] - But I don't understand how it works. If I watch firewall logs, I see a bunch of login chatter between server.saas.lan and dc.saas.lan I also see a bunch of DROPPED chatter between server.saas.lan and dc.corp.lan. Presumably, this is because server.saas.lan is trying to authenticate [email protected] But no firewall rule exists that allows communication between these hosts. However, [email protected] can log in successfully to server.saas.lan - Once logged in, I can "echo %logonserver%" and get \dc.corp.lan. So.... I am a little confused how the account actually gets authenticated. Does dc.saas.lan eventually talk to dc.corp.lan after server.saas.lan can't talk to dc.corp.lan? Just trying to figure out what needs to be changed/fixed/altered.

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• C#/.NET Little Wonders: The ConcurrentDictionary

  - by James Michael Hare

  Once again we consider some of the lesser known classes and keywords of C#.  In this series of posts, we will discuss how the concurrent collections have been developed to help alleviate these multi-threading concerns.  Last week’s post began with a general introduction and discussed the ConcurrentStack<T> and ConcurrentQueue<T>.  Today's post discusses the ConcurrentDictionary<T> (originally I had intended to discuss ConcurrentBag this week as well, but ConcurrentDictionary had enough information to create a very full post on its own!).  Finally next week, we shall close with a discussion of the ConcurrentBag<T> and BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. Recap As you'll recall from the previous post, the original collections were object-based containers that accomplished synchronization through a Synchronized member.  While these were convenient because you didn't have to worry about writing your own synchronization logic, they were a bit too finely grained and if you needed to perform multiple operations under one lock, the automatic synchronization didn't buy much. With the advent of .NET 2.0, the original collections were succeeded by the generic collections which are fully type-safe, but eschew automatic synchronization.  This cuts both ways in that you have a lot more control as a developer over when and how fine-grained you want to synchronize, but on the other hand if you just want simple synchronization it creates more work. With .NET 4.0, we get the best of both worlds in generic collections.  A new breed of collections was born called the concurrent collections in the System.Collections.Concurrent namespace.  These amazing collections are fine-tuned to have best overall performance for situations requiring concurrent access.  They are not meant to replace the generic collections, but to simply be an alternative to creating your own locking mechanisms. Among those concurrent collections were the ConcurrentStack<T> and ConcurrentQueue<T> which provide classic LIFO and FIFO collections with a concurrent twist.  As we saw, some of the traditional methods that required calls to be made in a certain order (like checking for not IsEmpty before calling Pop()) were replaced in favor of an umbrella operation that combined both under one lock (like TryPop()). Now, let's take a look at the next in our series of concurrent collections!For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here. ConcurrentDictionary – the fully thread-safe dictionary The ConcurrentDictionary<TKey,TValue> is the thread-safe counterpart to the generic Dictionary<TKey, TValue> collection.  Obviously, both are designed for quick – O(1) – lookups of data based on a key.  If you think of algorithms where you need lightning fast lookups of data and don’t care whether the data is maintained in any particular ordering or not, the unsorted dictionaries are generally the best way to go. Note: as a side note, there are sorted implementations of IDictionary, namely SortedDictionary and SortedList which are stored as an ordered tree and a ordered list respectively.  While these are not as fast as the non-sorted dictionaries – they are O(log2 n) – they are a great combination of both speed and ordering -- and still greatly outperform a linear search. Now, once again keep in mind that if all you need to do is load a collection once and then allow multi-threaded reading you do not need any locking.  Examples of this tend to be situations where you load a lookup or translation table once at program start, then keep it in memory for read-only reference.  In such cases locking is completely non-productive. However, most of the time when we need a concurrent dictionary we are interleaving both reads and updates.  This is where the ConcurrentDictionary really shines!  It achieves its thread-safety with no common lock to improve efficiency.  It actually uses a series of locks to provide concurrent updates, and has lockless reads!  This means that the ConcurrentDictionary gets even more efficient the higher the ratio of reads-to-writes you have. ConcurrentDictionary and Dictionary differences For the most part, the ConcurrentDictionary<TKey,TValue> behaves like it’s Dictionary<TKey,TValue> counterpart with a few differences.  Some notable examples of which are: Add() does not exist in the concurrent dictionary. This means you must use TryAdd(), AddOrUpdate(), or GetOrAdd().  It also means that you can’t use a collection initializer with the concurrent dictionary. TryAdd() replaced Add() to attempt atomic, safe adds. Because Add() only succeeds if the item doesn’t already exist, we need an atomic operation to check if the item exists, and if not add it while still under an atomic lock. TryUpdate() was added to attempt atomic, safe updates. If we want to update an item, we must make sure it exists first and that the original value is what we expected it to be.  If all these are true, we can update the item under one atomic step. TryRemove() was added to attempt atomic, safe removes. To safely attempt to remove a value we need to see if the key exists first, this checks for existence and removes under an atomic lock. AddOrUpdate() was added to attempt an thread-safe “upsert”. There are many times where you want to insert into a dictionary if the key doesn’t exist, or update the value if it does.  This allows you to make a thread-safe add-or-update. GetOrAdd() was added to attempt an thread-safe query/insert. Sometimes, you want to query for whether an item exists in the cache, and if it doesn’t insert a starting value for it.  This allows you to get the value if it exists and insert if not. Count, Keys, Values properties take a snapshot of the dictionary. Accessing these properties may interfere with add and update performance and should be used with caution. ToArray() returns a static snapshot of the dictionary. That is, the dictionary is locked, and then copied to an array as a O(n) operation.  GetEnumerator() is thread-safe and efficient, but allows dirty reads. Because reads require no locking, you can safely iterate over the contents of the dictionary.  The only downside is that, depending on timing, you may get dirty reads. Dirty reads during iteration The last point on GetEnumerator() bears some explanation.  Picture a scenario in which you call GetEnumerator() (or iterate using a foreach, etc.) and then, during that iteration the dictionary gets updated.  This may not sound like a big deal, but it can lead to inconsistent results if used incorrectly.  The problem is that items you already iterated over that are updated a split second after don’t show the update, but items that you iterate over that were updated a split second before do show the update.  Thus you may get a combination of items that are “stale” because you iterated before the update, and “fresh” because they were updated after GetEnumerator() but before the iteration reached them. Let’s illustrate with an example, let’s say you load up a concurrent dictionary like this: 1: // load up a dictionary. 2: var dictionary = new ConcurrentDictionary<string, int>(); 3:  4: dictionary["A"] = 1; 5: dictionary["B"] = 2; 6: dictionary["C"] = 3; 7: dictionary["D"] = 4; 8: dictionary["E"] = 5; 9: dictionary["F"] = 6; Then you have one task (using the wonderful TPL!) to iterate using dirty reads: 1: // attempt iteration in a separate thread 2: var iterationTask = new Task(() => 3: { 4: // iterates using a dirty read 5: foreach (var pair in dictionary) 6: { 7: Console.WriteLine(pair.Key + ":" + pair.Value); 8: } 9: }); And one task to attempt updates in a separate thread (probably): 1: // attempt updates in a separate thread 2: var updateTask = new Task(() => 3: { 4: // iterates, and updates the value by one 5: foreach (var pair in dictionary) 6: { 7: dictionary[pair.Key] = pair.Value + 1; 8: } 9: }); Now that we’ve done this, we can fire up both tasks and wait for them to complete: 1: // start both tasks 2: updateTask.Start(); 3: iterationTask.Start(); 4:  5: // wait for both to complete. 6: Task.WaitAll(updateTask, iterationTask); Now, if I you didn’t know about the dirty reads, you may have expected to see the iteration before the updates (such as A:1, B:2, C:3, D:4, E:5, F:6).  However, because the reads are dirty, we will quite possibly get a combination of some updated, some original.  My own run netted this result: 1: F:6 2: E:6 3: D:5 4: C:4 5: B:3 6: A:2 Note that, of course, iteration is not in order because ConcurrentDictionary, like Dictionary, is unordered.  Also note that both E and F show the value 6.  This is because the output task reached F before the update, but the updates for the rest of the items occurred before their output (probably because console output is very slow, comparatively). If we want to always guarantee that we will get a consistent snapshot to iterate over (that is, at the point we ask for it we see precisely what is in the dictionary and no subsequent updates during iteration), we should iterate over a call to ToArray() instead: 1: // attempt iteration in a separate thread 2: var iterationTask = new Task(() => 3: { 4: // iterates using a dirty read 5: foreach (var pair in dictionary.ToArray()) 6: { 7: Console.WriteLine(pair.Key + ":" + pair.Value); 8: } 9: }); The atomic Try…() methods As you can imagine TryAdd() and TryRemove() have few surprises.  Both first check the existence of the item to determine if it can be added or removed based on whether or not the key currently exists in the dictionary: 1: // try add attempts an add and returns false if it already exists 2: if (dictionary.TryAdd("G", 7)) 3: Console.WriteLine("G did not exist, now inserted with 7"); 4: else 5: Console.WriteLine("G already existed, insert failed."); TryRemove() also has the virtue of returning the value portion of the removed entry matching the given key: 1: // attempt to remove the value, if it exists it is removed and the original is returned 2: int removedValue; 3: if (dictionary.TryRemove("C", out removedValue)) 4: Console.WriteLine("Removed C and its value was " + removedValue); 5: else 6: Console.WriteLine("C did not exist, remove failed."); Now TryUpdate() is an interesting creature.  You might think from it’s name that TryUpdate() first checks for an item’s existence, and then updates if the item exists, otherwise it returns false.  Well, note quite... It turns out when you call TryUpdate() on a concurrent dictionary, you pass it not only the new value you want it to have, but also the value you expected it to have before the update.  If the item exists in the dictionary, and it has the value you expected, it will update it to the new value atomically and return true.  If the item is not in the dictionary or does not have the value you expected, it is not modified and false is returned. 1: // attempt to update the value, if it exists and if it has the expected original value 2: if (dictionary.TryUpdate("G", 42, 7)) 3: Console.WriteLine("G existed and was 7, now it's 42."); 4: else 5: Console.WriteLine("G either didn't exist, or wasn't 7."); The composite Add methods The ConcurrentDictionary also has composite add methods that can be used to perform updates and gets, with an add if the item is not existing at the time of the update or get. The first of these, AddOrUpdate(), allows you to add a new item to the dictionary if it doesn’t exist, or update the existing item if it does.  For example, let’s say you are creating a dictionary of counts of stock ticker symbols you’ve subscribed to from a market data feed: 1: public sealed class SubscriptionManager 2: { 3: private readonly ConcurrentDictionary<string, int> _subscriptions = new ConcurrentDictionary<string, int>(); 4:  5: // adds a new subscription, or increments the count of the existing one. 6: public void AddSubscription(string tickerKey) 7: { 8: // add a new subscription with count of 1, or update existing count by 1 if exists 9: var resultCount = _subscriptions.AddOrUpdate(tickerKey, 1, (symbol, count) => count + 1); 10:  11: // now check the result to see if we just incremented the count, or inserted first count 12: if (resultCount == 1) 13: { 14: // subscribe to symbol... 15: } 16: } 17: } Notice the update value factory Func delegate.  If the key does not exist in the dictionary, the add value is used (in this case 1 representing the first subscription for this symbol), but if the key already exists, it passes the key and current value to the update delegate which computes the new value to be stored in the dictionary.  The return result of this operation is the value used (in our case: 1 if added, existing value + 1 if updated). Likewise, the GetOrAdd() allows you to attempt to retrieve a value from the dictionary, and if the value does not currently exist in the dictionary it will insert a value.  This can be handy in cases where perhaps you wish to cache data, and thus you would query the cache to see if the item exists, and if it doesn’t you would put the item into the cache for the first time: 1: public sealed class PriceCache 2: { 3: private readonly ConcurrentDictionary<string, double> _cache = new ConcurrentDictionary<string, double>(); 4:  5: // adds a new subscription, or increments the count of the existing one. 6: public double QueryPrice(string tickerKey) 7: { 8: // check for the price in the cache, if it doesn't exist it will call the delegate to create value. 9: return _cache.GetOrAdd(tickerKey, symbol => GetCurrentPrice(symbol)); 10: } 11:  12: private double GetCurrentPrice(string tickerKey) 13: { 14: // do code to calculate actual true price. 15: } 16: } There are other variations of these two methods which vary whether a value is provided or a factory delegate, but otherwise they work much the same. Oddities with the composite Add methods The AddOrUpdate() and GetOrAdd() methods are totally thread-safe, on this you may rely, but they are not atomic.  It is important to note that the methods that use delegates execute those delegates outside of the lock.  This was done intentionally so that a user delegate (of which the ConcurrentDictionary has no control of course) does not take too long and lock out other threads. This is not necessarily an issue, per se, but it is something you must consider in your design.  The main thing to consider is that your delegate may get called to generate an item, but that item may not be the one returned!  Consider this scenario: A calls GetOrAdd and sees that the key does not currently exist, so it calls the delegate.  Now thread B also calls GetOrAdd and also sees that the key does not currently exist, and for whatever reason in this race condition it’s delegate completes first and it adds its new value to the dictionary.  Now A is done and goes to get the lock, and now sees that the item now exists.  In this case even though it called the delegate to create the item, it will pitch it because an item arrived between the time it attempted to create one and it attempted to add it. Let’s illustrate, assume this totally contrived example program which has a dictionary of char to int.  And in this dictionary we want to store a char and it’s ordinal (that is, A = 1, B = 2, etc).  So for our value generator, we will simply increment the previous value in a thread-safe way (perhaps using Interlocked): 1: public static class Program 2: { 3: private static int _nextNumber = 0; 4:  5: // the holder of the char to ordinal 6: private static ConcurrentDictionary<char, int> _dictionary 7: = new ConcurrentDictionary<char, int>(); 8:  9: // get the next id value 10: public static int NextId 11: { 12: get { return Interlocked.Increment(ref _nextNumber); } 13: } Then, we add a method that will perform our insert: 1: public static void Inserter() 2: { 3: for (int i = 0; i < 26; i++) 4: { 5: _dictionary.GetOrAdd((char)('A' + i), key => NextId); 6: } 7: } Finally, we run our test by starting two tasks to do this work and get the results… 1: public static void Main() 2: { 3: // 3 tasks attempting to get/insert 4: var tasks = new List<Task> 5: { 6: new Task(Inserter), 7: new Task(Inserter) 8: }; 9:  10: tasks.ForEach(t => t.Start()); 11: Task.WaitAll(tasks.ToArray()); 12:  13: foreach (var pair in _dictionary.OrderBy(p => p.Key)) 14: { 15: Console.WriteLine(pair.Key + ":" + pair.Value); 16: } 17: } If you run this with only one task, you get the expected A:1, B:2, ..., Z:26.  But running this in parallel you will get something a bit more complex.  My run netted these results: 1: A:1 2: B:3 3: C:4 4: D:5 5: E:6 6: F:7 7: G:8 8: H:9 9: I:10 10: J:11 11: K:12 12: L:13 13: M:14 14: N:15 15: O:16 16: P:17 17: Q:18 18: R:19 19: S:20 20: T:21 21: U:22 22: V:23 23: W:24 24: X:25 25: Y:26 26: Z:27 Notice that B is 3?  This is most likely because both threads attempted to call GetOrAdd() at roughly the same time and both saw that B did not exist, thus they both called the generator and one thread got back 2 and the other got back 3.  However, only one of those threads can get the lock at a time for the actual insert, and thus the one that generated the 3 won and the 3 was inserted and the 2 got discarded.  This is why on these methods your factory delegates should be careful not to have any logic that would be unsafe if the value they generate will be pitched in favor of another item generated at roughly the same time.  As such, it is probably a good idea to keep those generators as stateless as possible. Summary The ConcurrentDictionary is a very efficient and thread-safe version of the Dictionary generic collection.  It has all the benefits of type-safety that it’s generic collection counterpart does, and in addition is extremely efficient especially when there are more reads than writes concurrently. Tweet Technorati Tags: C#, .NET, Concurrent Collections, Collections, Little Wonders, Black Rabbit Coder,James Michael Hare

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• How do I do a cross-platform backup/restore of a DB2 database?

  - by Pridkett

  I need to dump a couple of databases from DB2 for Mac and DB2 for Linux and then import the databases to DB2 for Windows. Unfortunately, when I try the standard backup and restore I get the following error: SQL2570N An attempt to restore on target OS "NT-32" from a backup created on source OS "?" failed due to the incompatability of operating systems or an incorrect specification of the restore command. Reason-code: "1". I've seen references to DB2 needing an IXF dump and import, but I can't find any solid information about how to do this without dozens of other steps. Any hints on how to do this in the least painful manner?

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• How can I make the Windows 7 taskbar behave like a cross between the old Quick Launch and new Superbar?

  - by frumious

  I really like the taskbar in Windows 7, I think combining buttons to launch apps and the icons that show your running apps is groovy. However, because I like having as much space as possible, I've got small icons enabled and shrunk the bar down to one row. I've also told it not to group the running apps unless there's no space left (to save me having to work harder to find the particular window I want), which also means that they have captions, and are thus quite wide. The (admittedly small) problem this gives me is that I can pin all my favourite apps to the bar, which looks much like the old Quick Launch bar, but when I launch them the running apps because much wider, and the unlaunched apps get lost amongst them. I can manually change the order to fix this, but next time I'll launch a different app and I'll be back to square one. What I'd prefer is for small unlaunched icons to be kept on the left, and wider running apps to move over to the right, which for me would be the best of both worlds. Is there any way I can organise that? I'm aware that one can use the traditional quick launch bar in Windows 7, but that's not what I'm after; I generally prefer the Windows 7 way.

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• 10Gbe sfp+ Cross Over Cable required? Is there such a thing?

  - by dc-patos

  To preface, this is my first experience with 10GBe networking and I have encountered an issue which research does not seem to document a solution for... I have two servers (older DL580G5 and DL380G5), each with a HP NC522SFP 10Gbe dual sfp+ port adapter. I have purchased copper "passive" direct connect adapter cables (which look like twinax), which seem to work well when I connect them to the sfp+ ports on my Dell 5524 switch. However, if I directly connect the two servers with the same cable, the link doesn't come up. I am running WS2012 standard on each server. My intention is to use one of these servers as a home brew SAN and I would like to enable mutiple 10Gbe paths for iSCSI traffic. My question(s): Can I connect the two adapters to each other, such as I would with other less speedy generations of ethernet? If I can, do I require a crossover cable, or some type of other sfp+ cable solution to do this? My 10Gbe sfp+ switch ports are premium, but server to server connections are doable in small numbers for me and I would really like the multiple paths this would give me. Is there a simple solution?

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• Using INotifyPropertyChanged in background threads

  - by digitaldias

  Following up on a previous blog post where I exemplify databinding to objects, a reader was having some trouble with getting the UI to update. Here’s the rough UI: The idea is, when pressing Start, a background worker process starts ticking at the specified interval, then proceeds to increment the databound Elapsed value. The problem is that event propagation is limeted to current thread, meaning, you fire an event in one thread, then other threads of the same application will not catch it. The Code behind So, somewhere in my ViewModel, I have a corresponding bethod Start that initiates a background worker, for example: public void Start( ) { BackgroundWorker backgroundWorker = new BackgroundWorker( ); backgroundWorker.DoWork += IncrementTimerValue; backgroundWorker.RunWorkerAsync( ); } protected void IncrementTimerValue( object sender, DoWorkEventArgs e ) { do { if( this.ElapsedMs == 100 ) this.ElapsedMs = 0; else this.ElapsedMs++; }while( true ); } Assuming that there is a property: public int ElapsedMs { get { return _elapsedMs; } set { if( _elapsedMs == value ) return; _elapsedMs = value; NotifyThatPropertyChanged( "ElapsedMs" ); } } The above code will not work. If you step into this code in debug, you will find that INotifyPropertyChanged is called, but it does so in a different thread, and thus the UI never catches it, and does not update. One solution Knowing that the background thread updates the ElapsedMs member gives me a chance to activate BackgroundWorker class’ progress reporting mechanism to simply alert the main thread that something has happened, and that it is probably a good idea to refresh the ElapsedMs binding. public void Start( ) { BackgroundWorker backgroundWorker = new BackgroundWorker( ); backgroundWorker.DoWork += IncrementTimerValue; // Listen for progress report events backgroundWorker.WorkerReportsProgress = true; // Tell the UI that ElapsedMs needs to update backgroundWorker.RunWorkerCompleted += ( sender, e ) => { NotifyThatPropertyChanged( "ElapsedMs" ) }; backgroundWorker.RunWorkerAsync( ); } protected void IncrementTimerValue( object sender, DoWorkEventArgs e ) { do { if( this.ElapsedMs == 100 ) this.ElapsedMs = 0; else this.ElapsedMs++; // report any progress ( sender as BackgroundWorker ).ReportProgress( 0 ); }while( true ); } What happens above now is that I’ve used the BackgroundWorker cross thread mechanism to alert me of when it is ok for the UI to update it’s ElapsedMs field. Because the property itself is being updated in a different thread, I’m removing the NotifyThatPropertyChanged call from it’s Set method, and moving that responsability to the anonymous method that I created in the Start method. This is one way of solving the issue of having a background thread update your UI. I would be happy to hear of other cross-threading mechanisms for working in a MCP/MVC/MVVM pattern.

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• Is this Cross-browser Test mean that IE 9.0 is the best ?

  - by Space Cracker

  Is the results in this http://samples.msdn.microsoft.com/ietestcenter mean that IE 9.0 will be the best of all browsers next years ?

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• EMC/Legato/Networker Failed to recover files : Cross Platform Recovery not supported.

  - by marc.riera

  Software used to backup: EMC / Legato Networker legato server : windows legato clients: same hardware (2 years ago fedora something , now ubuntu ) Trying to recover from an old client, which is no longer available. So this is the thing. On 07/20/2008 we backed up a samba server(fedora something) to a tape , setting 1 year as browse policy and retention policy. Now this tape is recyclable. We took down the dns name. We deleted the legato client configuration. That legato client was reinstalled and is doing other stuff on ubuntu 10.04, with a different name but same ip. Now, 2 years and some month later #### Now we need to recover a folder from 2008 backup, on the fedora-samba-server. First thing, legato does not show the client name because the config was deleted. We create it again. We just set the old dns back on track, pointing the same ip, where the old server was, same MAC address ;). We created a new 'old client configuration' pointing to the new server. (different legato ip for client "I suppose" ) The ssid where the needed folder is on 2 tapes, 20 and 22. The index for that backup is on tape 21. We put this tapes on the jukebox (IBMT4000) -- not important for the issue -- All three tapes expired its browsable and recoverable time. So they are on recyclable. We get the clone id from the ssid with following command: mminfo -avot -q "ssid=<ssid>" -r cloneid We set the tapes to notrecyclable nsrmm -S <ssid>/<cloneid> -o notrecyclable We change the retention for the tapes for a future date nsrmm -S <ssid> -e 01/20/2011 We check the dates are correct : mminf -avV -q "ssid=<ssid>" -r ssbrowse(26),ssretent(26),savetime So far its OK. We close the terminal. Restart the server, just for being sure. Finally, we recover the index for that ssid where the folder should be. nsrck -L7 -t "07/20/2008" oldservername.domain.org There, we open the Networker User, select the server, select the old client as source, select the new client as destination. And this is what I get. imgur image of output -- http://i.imgur.com/1nOr8.png Should I understand that I need to install whatsoever operating system that was running on the old "linux server"/"networker client" to be able to restore 26Mb of files? thanks

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• Apart from visually looking - is there a way of calculating when a trendline will cross another seri

  - by Adrian

  That is to get a exact answer rather than a visual reading.

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