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  • Can't connect nonlocally after 12.10 upgrade

    - by user101815
    I've just upgraded one of my systems from 12.04 to 12.10. Now I can't connect on that system beyond my local network. Connections within the local network seem to work fine, and I can make nonlocal connections from other machines (like the one I'm asking this question from). I suspect that some routing information has been messed up, but I don't know where to look for it. It's not a nameserver problem -- pinging outside sites by their IP addresses doesn't work either. I have another laptop next to this one, also running Kubuntu 12.10. On the one that can't connect, arp produces no output. On the other one, it produces 192.168.0.1 ether 00:23:69:fa:ce:ae C wlan0 On the working machine, the output of netstat starts with some tcp entries. On the nonworking one, those entries are absent. I asked this question on the Ubuntu forum but haven't gotten any answers there. One further complication: since the troublesome machine has no outside connection, it's extremely difficult to download anything to it. For what it's worth, "ping 8.8.8.8" produces "connect: Network is unreachable". Update: after a lot of fiddling, I have my external world back. I don't know what the key action was, but the first indication of progress was that "ping 8.8.8.8" worked. At that point I still didn't have a working nameserver, so external URLs didn't work. But I did this (based on an online post, of course): sudo dpkg-reconfigure resolvconf and answered Yes to all prompts. That did the trick!! Apparently my problem was unique, or close to it, since I couldn't find any online references to it: local net working, remote net not working, including explicit IP addresses. So I suppose that if no one else has this problem, no one cares about the solution!!

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  • Website migration from WordPress to a static site and doing 301 redirects without access to existing site?

    - by user3114468
    Currently working on a project that is a hosted on WordPress that is being migrated to a static site. However I presently do not have access to the existing site as it's managed by another developer. The concern is not the lack of having access to content as the site owner has generated very little content (reason for migration) and we were able to do this manually. Rather the concern is to do 301 redirects. The site will not change domains but URLs such as from example.com/?page_id=3 to example.com/services. To add, the site is migrating to new server using same domain name. I thought maybe this could be done via editing permalinks prior to migration and WordPress would update automatically if configured to write on server. But if not configured (as this is not always the case) I do not have htaccess to fix it in case there are suddenly a bunch of 404 errors for every page. Really could use some help on the best procedure to follow in this case. This is the first migration project I've worked on.

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  • Role based access to resources for a RESTful service

    - by mutex
    I'm still wrapping my head around REST, but I wonder if someone can help with any suggestions or approaches to role based access control for a RESTful service, particularly from the point of view of securing the data and how the URLs might look. It's probably best to consider an example: Say I have a REST service for Customers, and want to split the users of this REST service into Admin, Editor and Reader roles: Admins can change all attributes of a Customer resource Editors can change only some Readers can only view them. Access control rights are assigned to the Customers entities individually. So for example a user of the service might have admin rights to Customers 1,2 and 3 but Editor access to 4,5 and Reader access to 7,8,9. Now consider the user calling the service. What is a good way to seperate the list of Customers for the current User? GET /Customer - this might get a list of all customers that the current user has Admin\Editor\Reader access to. But then on each Customer the consumer would need an indication of what role they have. Or would it be "better" having something like GET /Customer/Admin - return all customers the current user has Admin access to. Just looking for some high level pointers or reading on a decent way to secure\filter the resources based on roles of the current user.

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  • How should I structure a site with content dependent on visitor type (not user)?

    - by Pedr
    I have a website that displays different content depending on two selections made by a visitor: Whether they are a teacher or student, and their learning level (from 4 options). Everything is public and they don't need to authenticate to access the content. Depending on their selection, different content is displayed across the whole site, other than a contact and about page. The tone of the language changes depending on whether the visitor is a student or teacher and the materials available on each page also change depending on the learning level, however in all cases, the structure of the site is identical. Currently I'm using a cookie to store the visitor's selections and render different content appropriately, so I have a single set of URLs which display different content depending on the cookie, with one of the permutations as default. I appreciate this is far from ideal, but what is the better option? Would I be better using a distinguishing segment for each selection, for example: http://example.com/teacher/lv3/resources/activities http://example.com/teacher/lv4/resources/activities http://example.com/student/lv4/resources/activities etc. What is the most sensible way to handle this situation?

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  • How to build an API on top of an existing Rails app with NodeJs and what architecture to use?

    - by javiayala
    The explanation I was recently hired by a company that has an old RoR 2.3 application with more than 100k users, a strong SEO strategy with more than 170k indexed urls, native android and ios applications and other custom-made mobile and web applications that rely on a not so good API from the same RoR app. They recently merged with a company from another country as an strategy to grow the business and the profit. They have almost the same stats, a similar strategy and mobile apps. We have just decided that we need to merge the data from both companies and to start a new app from scratch since the RoR app is to old and heavily patched and the app from the other company was built with a custom PHP framework without any documentation. The only good news is that both databases are in MySQL and have a similar structure. The challenge I need to build a new version that: can handle a lot of traffic, preserves the SEO strategies of both companies, serve 2 different domains, and have a strong API that can support legacy mobile apps from both companies and be ready for a new set of native apps. I want to use RoR 3.2 for the main web apps and NodeJs with a Restful API. I know that I need to be very careful with the mobile apps and handle multiple versions of the API. I also think that I need to create a service that can handle a lot IO request since the apps is heavily used to create orders for restaurants at a certain time of the day. The questions With all this in mind: What type of architecture do you recommend me to follow? What gems or node packages do you think will work the best? How do I build a new rails app and keep using the same database structure? Should I use NodeJS to build an API or just build a new service with Ruby? I know that I'm asking to much from you guys, but please help me by answering any topic that you can or by pointing me on the right direction. All your comments and feedback will be extremely appreciated! Thanks!

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  • SEO Blog Indexing : Dot Wordpress Versus a Registered Domain?

    - by rumspringa00
    I've used Wordpress for a few of my client's sites, mostly small businesses and ecommerce sites. I have found through Google Analytics as well as the All in One Webmaster plugin that when it comes to social media, using Wordpress is a surefire way of getting your site indexed by Google and occasionally Bing and Yahoo. Since I am a heavy WP user, I'd like to contribute by registering a dot Wordpress domain for my portfolio. When using a WP installation concurrently with a WP domain, e.g. myportfolio.wordpress.com, will the site be more or less likely to be indexed rather a generic myportfolio.com domain? I've seen mixed opinions where people seem to favor a WP domain for URL output where others say that it's a moot point, and that Google will not favor a WP domain over a dot com domain as long as your meta tags are updated and content is keyword optimized. I tend to disagree and believe a WP domian would more likely be indexed and output more URLs over an individual, laconic domain like myportfolio.com. Am I wrong? Thanks in advance!

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  • SEO consideration for duplicate sites

    - by Malk
    I am building a brochure-ware website for a company that sells products all across the world. They need the site to ask the user what region they are in before using the site; there are 5 regions. This is because there are different products offered to different regions and each region may or may not want to customize their own content. However, at launch and likely forever, most of the pages will be the exact same minus what is listed in the footer and in the product selection menu. My question is how should I structure the sitemap for this site for best SEO? Should I be concerned with duplicate content penalties and/or cannibalizing the site's presence on the SERP? Some considerations: The client wants to be able to print links directly to regional specific content bypassing any prompt for the user to select a region (to ensure they land on the target page). The client cannot have a 'default' region so the user must have a region specified "Clean" urls are important, but there is wiggle room The client does not want each region to have its own domain There will be a link on the page to allow users to specify a different region The client is not concerned with localization ...at this time Some products are available in multiple regions A quick list of options I am considering: www.site.com/region/page region.site.com/page www.site.com/page?region (no cookie, pages require the parameter. If visited without; the user must select a region) www.site.com/page (using cookie and a splash screen if needed; could pass parameter in to set the region for direct linking) Thanks in advance for your advice.

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  • What kind of redirect (301 or 302) for an email links tracker?

    - by MaxiWheat
    We are developing an email sending application ("à la" Mailchimp). Hyperlinks inserted by our users, in the emails they want to send, are replaced by a tracking URL on our application (https://ourdomain.com/trackingurl?blablabla) which then redirects the email reader to the original URL our users included in their emails. This allows us to record statistics about link clicks. Until now, we used 301 for those redirections, but we noticed that Google began indexing pages on our application which are in fact redirects to other domains. (The title and snippet in Google results are from the other domain, but the link in green is from our application). We took action by adding those urls to our robots.txt, but Google seems to take forever (months!) before removing them for its index and removing them by hand in Webmaster Tools would take a lot of time since there are lot. I would like to know which kind of HTTP redirect (301 or 302) is best suited for this kind of opreation ? Do you think switching to 302 redirects could improve this situation since we don't really want Google to index redirected links from our clients emails ?

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  • Using Subdomains for Newly Regional Company

    - by Taylord22
    The company I work for is expanding their business to new territories. I've got a lot of stabilization to do in the region/state where we're one of the most well known companies of our kind. Currently, we have 3 distinct product lines which are currently distinguished by 3 separate URLS. This is affecting the user flow of our site, so we'd like to clean it up before launching our products into the various regions. The business has decided to grow into 5 new states (one state consisting of one county only) — none of which will feature all 3 products. Our homebase state is the only one that will have all 3 products this year. My initial thought was to use subdomains to separate out the regions, that way we could use a canonical tag to stabilize the root domain (which would feature home state content, and support content for all regions), and remove us from potential duplicate content penalization. Our product content will be nearly identical across the regions for the first year. I second guessed myself by thinking that it was perhaps better to use a "[product].root/region" URL instead. And I'm currently stuck by wondering if it was not better to build out subdomains for products and regions...using one modifier or the other as a funnel/branding page into the other. For instance, user lands on "region.root.com" and sees exactly what products we offer in that region. Basically, a tailored landing page. Meanwhile the bulk of the product content would actually live under "product.root.com/region/page". My head is spinning. And while searching for similar questions I also bumped into reference of another tag meant to be used in some similar cases to mine. I feel like there's a lot of risks involved in this subdomain strategy, but I also can't help but see the benefits in the user flow.

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  • ASP.Net MVC 3: multiple versions of the site without changing of URL, is it possible?

    - by Seacat
    Our website is written in ASP.NET MVC 3 and we want to change a feature in the core functionality of the site. The problem is not every client can be moved to this new version/format (because of some technical inner restrictions) so it means that we need to keep 2 versions of the same functionality (backend and frontend) simultaneously. We don't want our clients to worry about URLs, so the ideal solution would be keep the same URL but redirect clients to the different versions. The information about clients is stored in database. So the moment when user (client) logs in we know which version of site we should show. I'm thinking about routing and areas but I'm not sure if it's possible for example to have 2 areas with the different versions of the same application. Or is it possible to load the assemblies on the fly? After user is logged in we can decide if (s)he should be redirected to the new or old version. As far as all the clients have been moved to the new version we don't need this system more. How can I do this in ASP.NET MVC?

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  • Oracle ADF Mobile

    - by rituchhibber
    We are happy to announce that Oracle ADF Mobile is now available for our customers.Oracle ADF Mobile enables developer to build applications that install and run on both iOS and Android devices from one source code.Development is done with JDeveloper and ADF and leverages Java and HTML5 technologies, while keeping the same visual and declarative approach ADF is known for.Please Click here to read more about the Oracle ADF Mobile release and learn more on our OTN Page. Feature Highlights: Java - Oracle brings a Java VM embedded with each application so you can develop all your business logic in the platform neutral language you know and love! (Yes, even iOS!) JDBC - Since we give you Java, we also provide JDBC along with a SQLite driver and engine that also supports encryption out of the box. Multi-Platform - Truly develop your application only once and deploy to multiple platforms. iOS and Android platforms are supported for both phone and tablet. Flexible - You can decide how to implement the UI: Use existing server-based UI framework like JSF. Use your own favorite HTML5 framework like JQuery. Use our declarative HTML5 component set provided with the framework. Device Feature Access - You can get access to device features from either Java or JavaScript to invoke features like camera, GPS, email, SMS, contacts, etc. Secure - ADF Mobile provides integrated security that works with your server back-end as well. Whether you’re using remote URLs, local HTML or AMX, you can secure any/all of your features with a single consistent login page. Since we also give you SQLite encryption, we are assured that your data is safe. Rapid - Using the same development techniques that ADF developers are already used to, you can quickly create mobile applications without ever learning another language!ADF Mobile XML or AMX for short, provides all the normal input and layout controls you expect and we also add charts/maps/gauges along with it to provide a very comprehensive UI controls. You can also mix and match any of the three for ultimate flexibility!

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  • Week in Geek: New Security Flaw Confirmed for Internet Explorer Edition

    - by Asian Angel
    This week we learned how to use a PC to stay entertained while traveling for the holidays, create quality photo prints with free software, share links between any browser and any smartphone, create perfect Christmas photos using How-To Geek’s 10 best how-to photo guides, and had fun decorating Firefox with a collection of Holiday 2010 Personas themes. Photo by Repoort. Random Geek Links Photo by Asian Angel. Critical 0-Day Flaw Affects All Internet Explorer Versions, Microsoft Warns Microsoft has confirmed a zero-day vulnerability affecting all supported versions of Internet Explorer, including IE8, IE7 and IE6. Note: Article contains link to Microsoft Security Advisory detailing two work-arounds until a security update is released. Hackers targeting human rights, indie media groups Hackers are increasingly hitting the Web sites of human rights and independent media groups in an attempt to silence them, says a new study released this week by Harvard University’s Berkman Center for Internet & Society. OpenBSD: audits give no indication of back doors So far, the analyses of OpenBSD’s crypto and IPSec code have not provided any indication that the system contains back doors for listening to encrypted VPN connections. But the developers have already found two bugs during their current audits. Sophos: Beware Facebook’s new facial-recognition feature Facebook’s new facial recognition software might result in undesirable photos of users being circulated online, warned a security expert, who urged users to keep abreast with the social network’s privacy settings to prevent the abovementioned scenario from becoming a reality. Microsoft withdraws flawed Outlook update Microsoft has withdrawn update KB2412171 for Outlook 2007, released last Patch Tuesday, after a number of user complaints. Skype: Millions still without service Skype was still working to right itself going into the holiday weekend from a major outage that began this past Wednesday. Mozilla improves sync setup and WebGL in Firefox 4 beta 8 Firefox 4.0 beta 8 brings better support for WebGL and introduces an improved setup process for Firefox Sync that simplifies the steps for configuring the synchronization service across multiple devices. Chrome OS the litmus test for cloud The success or failure of Google’s browser-oriented Chrome OS will be the litmus test to decide if the cloud is capable of addressing user needs for content and services, according to a new Ovum report released Monday. FCC Net neutrality rules reach mobile apps The Federal Communications Commission (FCC) finally released its long-expected regulations on Thursday and the related explanations total a whopping 194 pages. One new item that was not previously disclosed: mobile wireless providers can’t block “applications that compete with the provider’s” own voice or video telephony services. KDE and the Document Foundation join Open Invention Network The KDE e.V. and the Document Foundation (TDF) have both joined the Open Invention Network (OIN) as licensees, expanding the organization’s roster of supporters. Report: SEC looks into Hurd’s ousting from HP The scandal surrounding Mark Hurd’s departure from the world’s largest technology company in August has officially drawn attention from the U.S. Securities and Exchange Commission. Report: Google requests delay of new Google TVs Google TV is apparently encountering a bit of static that has resulted in a programming change. Geek Video of the Week This week we have a double dose of geeky video goodness for you with the original Mac vs PC video and the trailer for the sequel. Photo courtesy of Peacer. Mac vs PC Photo courtesy of Peacer. Mac vs PC 2 Trailer Random TinyHacker Links Awesome Tools To Extract Audio From Video Here’s a list of really useful, and free tools to rip audio from videos. Getting Your iPhone Out of Recovery Mode Is your iPhone stuck in recovery mode? This tutorial will help you get it out of that state. Google Shared Spaces Quickly create a shared space and collaborate with friends online. McAfee Internet Security 2011 – Upgrade not worthy of a version change McAfee has released their 2011 version of security products. And as this review details, the upgrades are minimal when compared to their 2010 products. For more information, check out the review. 200 Countries Plotted Hans Rosling’s famous lectures combine enormous quantities of public data with a sport’s commentator’s style to reveal the story of the world’s past, present and future development. Now he explores stats in a way he has never done before – using augmented reality animation. Super User Questions Enjoy looking through this week’s batch of popular questions and answers from Super User. How to restore windows 7 to a known working state every time it boots? Is there an easy way to mass-transfer all files between two computers? Coffee spilled inside computer, damaged hard drive Computer does not boot after ram upgrade Keyboard not detected when trying to install Ubuntu 10.10 How-To Geek Weekly Article Recap Have you had a super busy week while preparing for the holiday weekend? Then here is your chance to get caught up on your reading with our five hottest articles for the week. Ask How-To Geek: Rescuing an Infected PC, Installing Bloat-free iTunes, and Taming a Crazy Trackpad How to Use the Avira Rescue CD to Clean Your Infected PC Eight Geektacular Christmas Projects for Your Day Off VirtualBox 4.0 Rocks Extensions and a Simplified GUI Ask the Readers: How Many Monitors Do You Use with Your Computer? One Year Ago on How-To Geek Here are more great articles from one year ago for you to read and enjoy during the holiday break. Enjoy Distraction-Free Writing with WriteMonkey Shutter is a State of Art Screenshot Tool for Ubuntu Get Hex & RGB Color Codes the Easy Way Find User Scripts for Your Favorite Websites the Easy Way Access Your Unsorted Bookmarks the Easy Way (Firefox) The Geek Note That “wraps” things up for this week and we hope that everyone enjoys the rest of their holiday break! Found a great tip during the break? Then be sure to send it in to us at [email protected]. Photo by ArSiSa7. Latest Features How-To Geek ETC How to Use the Avira Rescue CD to Clean Your Infected PC The Complete List of iPad Tips, Tricks, and Tutorials Is Your Desktop Printer More Expensive Than Printing Services? 20 OS X Keyboard Shortcuts You Might Not Know HTG Explains: Which Linux File System Should You Choose? HTG Explains: Why Does Photo Paper Improve Print Quality? Simon’s Cat Explores the Christmas Tree! [Video] The Outdoor Lights Scene from National Lampoon’s Christmas Vacation [Video] The Famous Home Alone Pizza Delivery Scene [Classic Video] Chronicles of Narnia: The Voyage of the Dawn Treader Theme for Windows 7 Cardinal and Rabbit Sharing a Tree on a Cold Winter Morning Wallpaper An Alternate Star Wars Christmas Special [Video]

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  • Parallelism in .NET – Part 10, Cancellation in PLINQ and the Parallel class

    - by Reed
    Many routines are parallelized because they are long running processes.  When writing an algorithm that will run for a long period of time, its typically a good practice to allow that routine to be cancelled.  I previously discussed terminating a parallel loop from within, but have not demonstrated how a routine can be cancelled from the caller’s perspective.  Cancellation in PLINQ and the Task Parallel Library is handled through a new, unified cooperative cancellation model introduced with .NET 4.0. Cancellation in .NET 4 is based around a new, lightweight struct called CancellationToken.  A CancellationToken is a small, thread-safe value type which is generated via a CancellationTokenSource.  There are many goals which led to this design.  For our purposes, we will focus on a couple of specific design decisions: Cancellation is cooperative.  A calling method can request a cancellation, but it’s up to the processing routine to terminate – it is not forced. Cancellation is consistent.  A single method call requests a cancellation on every copied CancellationToken in the routine. Let’s begin by looking at how we can cancel a PLINQ query.  Supposed we wanted to provide the option to cancel our query from Part 6: double min = collection .AsParallel() .Min(item => item.PerformComputation()); .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; } We would rewrite this to allow for cancellation by adding a call to ParallelEnumerable.WithCancellation as follows: var cts = new CancellationTokenSource(); // Pass cts here to a routine that could, // in parallel, request a cancellation try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation()); } catch (OperationCanceledException e) { // Query was cancelled before it finished } .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; } Here, if the user calls cts.Cancel() before the PLINQ query completes, the query will stop processing, and an OperationCanceledException will be raised.  Be aware, however, that cancellation will not be instantaneous.  When cts.Cancel() is called, the query will only stop after the current item.PerformComputation() elements all finish processing.  cts.Cancel() will prevent PLINQ from scheduling a new task for a new element, but will not stop items which are currently being processed.  This goes back to the first goal I mentioned – Cancellation is cooperative.  Here, we’re requesting the cancellation, but it’s up to PLINQ to terminate. If we wanted to allow cancellation to occur within our routine, we would need to change our routine to accept a CancellationToken, and modify it to handle this specific case: public void PerformComputation(CancellationToken token) { for (int i=0; i<this.iterations; ++i) { // Add a check to see if we've been canceled // If a cancel was requested, we'll throw here token.ThrowIfCancellationRequested(); // Do our processing now this.RunIteration(i); } } With this overload of PerformComputation, each internal iteration checks to see if a cancellation request was made, and will throw an OperationCanceledException at that point, instead of waiting until the method returns.  This is good, since it allows us, as developers, to plan for cancellation, and terminate our routine in a clean, safe state. This is handled by changing our PLINQ query to: try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation(cts.Token)); } catch (OperationCanceledException e) { // Query was cancelled before it finished } PLINQ is very good about handling this exception, as well.  There is a very good chance that multiple items will raise this exception, since the entire purpose of PLINQ is to have multiple items be processed concurrently.  PLINQ will take all of the OperationCanceledException instances raised within these methods, and merge them into a single OperationCanceledException in the call stack.  This is done internally because we added the call to ParallelEnumerable.WithCancellation. If, however, a different exception is raised by any of the elements, the OperationCanceledException as well as the other Exception will be merged into a single AggregateException. The Task Parallel Library uses the same cancellation model, as well.  Here, we supply our CancellationToken as part of the configuration.  The ParallelOptions class contains a property for the CancellationToken.  This allows us to cancel a Parallel.For or Parallel.ForEach routine in a very similar manner to our PLINQ query.  As an example, we could rewrite our Parallel.ForEach loop from Part 2 to support cancellation by changing it to: try { var cts = new CancellationTokenSource(); var options = new ParallelOptions() { CancellationToken = cts.Token }; Parallel.ForEach(customers, options, customer => { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // Check for cancellation here options.CancellationToken.ThrowIfCancellationRequested(); // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { theStore.EmailCustomer(customer); customer.LastEmailContact = DateTime.Now; } }); } catch (OperationCanceledException e) { // The loop was cancelled } Notice that here we use the same approach taken in PLINQ.  The Task Parallel Library will automatically handle our cancellation in the same manner as PLINQ, providing a clean, unified model for cancellation of any parallel routine.  The TPL performs the same aggregation of the cancellation exceptions as PLINQ, as well, which is why a single exception handler for OperationCanceledException will cleanly handle this scenario.  This works because we’re using the same CancellationToken provided in the ParallelOptions.  If a different exception was thrown by one thread, or a CancellationToken from a different CancellationTokenSource was used to raise our exception, we would instead receive all of our individual exceptions merged into one AggregateException.

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  • Parallelism in .NET – Part 18, Task Continuations with Multiple Tasks

    - by Reed
    In my introduction to Task continuations I demonstrated how the Task class provides a more expressive alternative to traditional callbacks.  Task continuations provide a much cleaner syntax to traditional callbacks, but there are other reasons to switch to using continuations… Task continuations provide a clean syntax, and a very simple, elegant means of synchronizing asynchronous method results with the user interface.  In addition, continuations provide a very simple, elegant means of working with collections of tasks. Prior to .NET 4, working with multiple related asynchronous method calls was very tricky.  If, for example, we wanted to run two asynchronous operations, followed by a single method call which we wanted to run when the first two methods completed, we’d have to program all of the handling ourselves.  We would likely need to take some approach such as using a shared callback which synchronized against a common variable, or using a WaitHandle shared within the callbacks to allow one to wait for the second.  Although this could be accomplished easily enough, it requires manually placing this handling into every algorithm which requires this form of blocking.  This is error prone, difficult, and can easily lead to subtle bugs. Similar to how the Task class static methods providing a way to block until multiple tasks have completed, TaskFactory contains static methods which allow a continuation to be scheduled upon the completion of multiple tasks: TaskFactory.ContinueWhenAll. This allows you to easily specify a single delegate to run when a collection of tasks has completed.  For example, suppose we have a class which fetches data from the network.  This can be a long running operation, and potentially fail in certain situations, such as a server being down.  As a result, we have three separate servers which we will “query” for our information.  Now, suppose we want to grab data from all three servers, and verify that the results are the same from all three. With traditional asynchronous programming in .NET, this would require using three separate callbacks, and managing the synchronization between the various operations ourselves.  The Task and TaskFactory classes simplify this for us, allowing us to write: var server1 = Task.Factory.StartNew( () => networkClass.GetResults(firstServer) ); var server2 = Task.Factory.StartNew( () => networkClass.GetResults(secondServer) ); var server3 = Task.Factory.StartNew( () => networkClass.GetResults(thirdServer) ); var result = Task.Factory.ContinueWhenAll( new[] {server1, server2, server3 }, (tasks) => { // Propogate exceptions (see below) Task.WaitAll(tasks); return this.CompareTaskResults( tasks[0].Result, tasks[1].Result, tasks[2].Result); }); .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 is clean, simple, and elegant.  The one complication is the Task.WaitAll(tasks); statement. Although the continuation will not complete until all three tasks (server1, server2, and server3) have completed, there is a potential snag.  If the networkClass.GetResults method fails, and raises an exception, we want to make sure to handle it cleanly.  By using Task.WaitAll, any exceptions raised within any of our original tasks will get wrapped into a single AggregateException by the WaitAll method, providing us a simplified means of handling the exceptions.  If we wait on the continuation, we can trap this AggregateException, and handle it cleanly.  Without this line, it’s possible that an exception could remain uncaught and unhandled by a task, which later might trigger a nasty UnobservedTaskException.  This would happen any time two of our original tasks failed. Just as we can schedule a continuation to occur when an entire collection of tasks has completed, we can just as easily setup a continuation to run when any single task within a collection completes.  If, for example, we didn’t need to compare the results of all three network locations, but only use one, we could still schedule three tasks.  We could then have our completion logic work on the first task which completed, and ignore the others.  This is done via TaskFactory.ContinueWhenAny: var server1 = Task.Factory.StartNew( () => networkClass.GetResults(firstServer) ); var server2 = Task.Factory.StartNew( () => networkClass.GetResults(secondServer) ); var server3 = Task.Factory.StartNew( () => networkClass.GetResults(thirdServer) ); var result = Task.Factory.ContinueWhenAny( new[] {server1, server2, server3 }, (firstTask) => { return this.ProcessTaskResult(firstTask.Result); }); .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; } Here, instead of working with all three tasks, we’re just using the first task which finishes.  This is very useful, as it allows us to easily work with results of multiple operations, and “throw away” the others.  However, you must take care when using ContinueWhenAny to properly handle exceptions.  At some point, you should always wait on each task (or use the Task.Result property) in order to propogate any exceptions raised from within the task.  Failing to do so can lead to an UnobservedTaskException.

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  • Convert a DVD Movie Directly to AVI with FairUse Wizard 2.9

    - by DigitalGeekery
    Are you looking for a way to backup your DVD movie collection to AVI?  Today we’ll show you how to rip a DVD movie directly to AVI with FairUse Wizard. About FairUse Wizard FairUse Wizard 2.9 uses the DivX, Xvid, or h.264 codec to convert DVD to an AVI file. It comes in both a free version and commercial version. The free, or “Light” version, can create files up 700MB while the commercial version can output a 1400MB file. This will allow you to back up your movies to CD, or even multiple movies on a single DVD. FairUse Wizard states that it does not work on copy protected discs, but we’ve seen it work on all but some of the most recent copy protection. For this tutorial we’re using the free Light Edition to convert a DVD to AVI. They also offer a commercial version that you can get for $29.99 and it offers even more encoding possibilities for converting video to you portable digital devices. Installation and Configuration Download and install FairUse Wizard. (Download link below). Once the install is complete, open FairUse Wizard by going to Start > All Programs >  FairUse Wizard 2 >  FairUse Wizard 2.   FairUse Wizard will open on the new project screen. Select “Create a new project” and type a project name into the text box. This will be used as the file output name.  Ex: A project name of Simpsons Movie will give you an output file of Simpsons Movie.avi.   Next, browse for a destination folder for the output file and temp files. Note that you will need a minimum of 6 GB of free disk space for the conversion process. Note: Much of that 6 GB will be used for temporary files that we will delete after the conversion process.   Click on the Options button at the bottom.   Under Preferences, choose your preferred video codec and file output size. XviD and x264 are installed by default. If you prefer to use DivX, you will have to install it separately. Also note the “Two pass” option. Checking the “Two pass” box will encode your video twice for higher quality, but will take more time. Un-checking the box will speed up the conversion process.   Under Audio track, note that English subtitles are enabled by default, so to remove the subtitles, you will need to change the dropdown list so it shows only a dash (-). You can also select “Use TV Mode” if your primary playback will be on a 4:3 TV screen. Click “Next.” Full Auto Mode vs. Manual Mode You should now be back to the initial screen. Next, we’ll need to determine whether or not we can use “Full Auto Mode” to convert the movie. The difference is that “Full Auto Mode” will automatically perform a few steps that you will otherwise have to do manually. If you choose the “Full Auto Mode” option, FairUse Wizard will look for the video on the DVD with the longest duration and assume it is the chain that it should convert to AVI. It’s possible, however, your disc may contain a few chains of similar size, such as a theatrical cut and director’s cut, and the longest chain may not be the one you wish to convert. Make sure that “Full auto mode” is not checked yet, and click “Next.”   FairUse Wizard will parse the IFO files and display all video chains longer than 60  seconds. In most cases, you will only find that the largest chain is the one closely matching the duration of the movie. In these instances, you can use “Full Auto Mode.” If you find more than one chain that are close in duration to the length of the movie, consult the literature on the DVD case, or search online, to find the actual running time of the movie. If the proper file chain is not the longest chain, you won’t be able to use “Full Auto Mode.”   Full Auto Mode To use “Full Auto Mode,” simply click the “Back” button to return to the initial screen Now, place a check in the “Full auto mode” check box. Click “Next.” You will then be prompted to chose your DVD drive, then click “OK.” FairUse Wizard will parse the IFO files… … and then prompt you to Select your drive that contains the DVD one more time before beginning the conversion process. Click “OK.”   Manual Mode If you cannot (or don’t wish to) use Full Auto Mode, choose the appropriate video chain and click “Next.” FairUse Wizard will first go through the process of indexing the video. Note: If you get a runtime error during this portion of the process, it likely means that FairUse Wizard cannot handle the copy protection, and thus cannot convert the DVD. FairUse Wizard will automatically detect a cropping region. If necessary, you can edit the cropping region by adjusting the cropping region settings to the left. Click “Next.” Next, click “Auto Detect” to choose the proper field combination. Click “OK” on the pop up window that displays your Field Mode. Then click “Next.” This next screen is mainly comprised of settings from the Options screen. You can make changes at this point such as codec or output size. Click “Next” when ready.   Video Conversion Now the video conversion process will begin. This may take a few hours depending on your system’s hardware. Note: There is a check box to “Shutdown computer when done” if you choose to run the conversion overnight or before leaving for work. The first phase will be video encoding… Then the audio… If you chose the “Two Pass” option, your video video will be encoded again on 2nd pass. Then you’re finished. Unfortunately, FairUse Wizard doesn’t clean up after itself very well. After the process is complete, you’ll want to browse to your output directory and delete all the temporary files as they take up a considerable amount of hard drive space. Now you’re ready to enjoy your movie. Conclusion FairUse Wizard is a nice way to backup your DVD movies to good quality .avi files. You can store them on your hard drive, watch them on a media PC, or burn them to disc. Many DVD players even allow for playback of DivX or XviD encoded video from a CD or DVD. For those of you with children, you can burn that AVI file to CD for your kids, and keep your original DVDs stored safely out of harms way. Download Download FairUse Wizard 2.9 LE Similar Articles Productive Geek Tips Kantaris is a Unique Media Player Based on VLCHow to Make/Edit a movie with Windows Movie Maker in Windows VistaAutomatically Mount and View ISO files in Windows 7 Media CenterTune Your ClearType Font Settings in Windows VistaAdd Images and Metadata to Windows 7 Media Center Movie Library TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Make your Joomla & Drupal Sites Mobile with OSMOBI Integrate Twitter and Delicious and Make Life Easier Design Your Web Pages Using the Golden Ratio Worldwide Growth of the Internet How to Find Your Mac Address Use My TextTools to Edit and Organize Text

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  • Class-Level Model Validation with EF Code First and ASP.NET MVC 3

    - by ScottGu
    Earlier this week the data team released the CTP5 build of the new Entity Framework Code-First library.  In my blog post a few days ago I talked about a few of the improvements introduced with the new CTP5 build.  Automatic support for enforcing DataAnnotation validation attributes on models was one of the improvements I discussed.  It provides a pretty easy way to enable property-level validation logic within your model layer. You can apply validation attributes like [Required], [Range], and [RegularExpression] – all of which are built-into .NET 4 – to your model classes in order to enforce that the model properties are valid before they are persisted to a database.  You can also create your own custom validation attributes (like this cool [CreditCard] validator) and have them be automatically enforced by EF Code First as well.  This provides a really easy way to validate property values on your models.  I showed some code samples of this in action in my previous post. Class-Level Model Validation using IValidatableObject DataAnnotation attributes provides an easy way to validate individual property values on your model classes.  Several people have asked - “Does EF Code First also support a way to implement class-level validation methods on model objects, for validation rules than need to span multiple property values?”  It does – and one easy way you can enable this is by implementing the IValidatableObject interface on your model classes. IValidatableObject.Validate() Method Below is an example of using the IValidatableObject interface (which is built-into .NET 4 within the System.ComponentModel.DataAnnotations namespace) to implement two custom validation rules on a Product model class.  The two rules ensure that: New units can’t be ordered if the Product is in a discontinued state New units can’t be ordered if there are already more than 100 units in stock We will enforce these business rules by implementing the IValidatableObject interface on our Product class, and by implementing its Validate() method like so: The IValidatableObject.Validate() method can apply validation rules that span across multiple properties, and can yield back multiple validation errors. Each ValidationResult returned can supply both an error message as well as an optional list of property names that caused the violation (which is useful when displaying error messages within UI). Automatic Validation Enforcement EF Code-First (starting with CTP5) now automatically invokes the Validate() method when a model object that implements the IValidatableObject interface is saved.  You do not need to write any code to cause this to happen – this support is now enabled by default. This new support means that the below code – which violates one of our above business rules – will automatically throw an exception (and abort the transaction) when we call the “SaveChanges()” method on our Northwind DbContext: In addition to reactively handling validation exceptions, EF Code First also allows you to proactively check for validation errors.  Starting with CTP5, you can call the “GetValidationErrors()” method on the DbContext base class to retrieve a list of validation errors within the model objects you are working with.  GetValidationErrors() will return a list of all validation errors – regardless of whether they are generated via DataAnnotation attributes or by an IValidatableObject.Validate() implementation.  Below is an example of proactively using the GetValidationErrors() method to check (and handle) errors before trying to call SaveChanges(): ASP.NET MVC 3 and IValidatableObject ASP.NET MVC 2 included support for automatically honoring and enforcing DataAnnotation attributes on model objects that are used with ASP.NET MVC’s model binding infrastructure.  ASP.NET MVC 3 goes further and also honors the IValidatableObject interface.  This combined support for model validation makes it easy to display appropriate error messages within forms when validation errors occur.  To see this in action, let’s consider a simple Create form that allows users to create a new Product: We can implement the above Create functionality using a ProductsController class that has two “Create” action methods like below: The first Create() method implements a version of the /Products/Create URL that handles HTTP-GET requests - and displays the HTML form to fill-out.  The second Create() method implements a version of the /Products/Create URL that handles HTTP-POST requests - and which takes the posted form data, ensures that is is valid, and if it is valid saves it in the database.  If there are validation issues it redisplays the form with the posted values.  The razor view template of our “Create” view (which renders the form) looks like below: One of the nice things about the above Controller + View implementation is that we did not write any validation logic within it.  The validation logic and business rules are instead implemented entirely within our model layer, and the ProductsController simply checks whether it is valid (by calling the ModelState.IsValid helper method) to determine whether to try and save the changes or redisplay the form with errors. The Html.ValidationMessageFor() helper method calls within our view simply display the error messages our Product model’s DataAnnotations and IValidatableObject.Validate() method returned.  We can see the above scenario in action by filling out invalid data within the form and attempting to submit it: Notice above how when we hit the “Create” button we got an error message.  This was because we ticked the “Discontinued” checkbox while also entering a value for the UnitsOnOrder (and so violated one of our business rules).  You might ask – how did ASP.NET MVC know to highlight and display the error message next to the UnitsOnOrder textbox?  It did this because ASP.NET MVC 3 now honors the IValidatableObject interface when performing model binding, and will retrieve the error messages from validation failures with it. The business rule within our Product model class indicated that the “UnitsOnOrder” property should be highlighted when the business rule we hit was violated: Our Html.ValidationMessageFor() helper method knew to display the business rule error message (next to the UnitsOnOrder edit box) because of the above property name hint we supplied: Keeping things DRY ASP.NET MVC and EF Code First enables you to keep your validation and business rules in one place (within your model layer), and avoid having it creep into your Controllers and Views.  Keeping the validation logic in the model layer helps ensure that you do not duplicate validation/business logic as you add more Controllers and Views to your application.  It allows you to quickly change your business rules/validation logic in one single place (within your model layer) – and have all controllers/views across your application immediately reflect it.  This help keep your application code clean and easily maintainable, and makes it much easier to evolve and update your application in the future. Summary EF Code First (starting with CTP5) now has built-in support for both DataAnnotations and the IValidatableObject interface.  This allows you to easily add validation and business rules to your models, and have EF automatically ensure that they are enforced anytime someone tries to persist changes of them to a database.  ASP.NET MVC 3 also now supports both DataAnnotations and IValidatableObject as well, which makes it even easier to use them with your EF Code First model layer – and then have the controllers/views within your web layer automatically honor and support them as well.  This makes it easy to build clean and highly maintainable applications. You don’t have to use DataAnnotations or IValidatableObject to perform your validation/business logic.  You can always roll your own custom validation architecture and/or use other more advanced validation frameworks/patterns if you want.  But for a lot of applications this built-in support will probably be sufficient – and provide a highly productive way to build solutions. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • WD MBWE II (White Strip Light) 2TB - unable to access data

    - by user210477
    I have a WD MBWE II (White Strip Light) 2TB - (WD20000H2NC-00) Was working fine until a few days ago. I guess there was a power failure and after that I am unable to access the 'Public' or the 'Download' folder anymore. I have been searching for answers everywhere but came up empty handed. Web GUI still works, SSH works. I hooked up both the drives on my PC and UFS Explorer sees the drive. But so far I am unable to retrieve any of my data. I do not remember what RAID setting I used when I first got the drive. I can see from GUI that it is set as "Stripe". The drive contains 10 years of family pictures which I really do not want to loose. Sadly and stupidly, I didn't even keep a backup of this drive. Can somebody please help or point me in the right direction. Thank you in advance for your help. Disk Utility on Ubuntu reports 1405 bad sectors on one drive. How can I retrieve my data? Please help. Logs below: ~ # mdadm --detail /dev/md[012345678] /dev/md0: Version : 0.90 Creation Time : Wed Jul 15 08:36:17 2009 Raid Level : raid1 Array Size : 1959872 (1914.26 MiB 2006.91 MB) Used Dev Size : 1959872 (1914.26 MiB 2006.91 MB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Fri Nov 1 13:53:29 2013 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 UUID : 04f7a661:98983b3b:26b29e4f:9b646adb Events : 0.266 Number Major Minor RaidDevice State 0 8 1 0 active sync /dev/sda1 1 8 17 1 active sync /dev/sdb1 /dev/md1: Version : 0.90 Creation Time : Wed Jul 15 08:36:18 2009 Raid Level : raid1 Array Size : 256896 (250.92 MiB 263.06 MB) Used Dev Size : 256896 (250.92 MiB 263.06 MB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 1 Persistence : Superblock is persistent Update Time : Wed Oct 30 22:08:21 2013 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 UUID : aaa7b859:c475312d:efc5a766:6526b867 Events : 0.10 Number Major Minor RaidDevice State 0 8 2 0 active sync /dev/sda2 1 8 18 1 active sync /dev/sdb2 /dev/md2: Version : 0.90 Creation Time : Sat Sep 25 10:01:26 2010 Raid Level : raid0 Array Size : 1947045760 (1856.85 GiB 1993.77 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 2 Persistence : Superblock is persistent Update Time : Fri Nov 1 13:30:53 2013 State : active Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Chunk Size : 64K UUID : 01dae60a:6831077b:77f74530:8680c183 Events : 0.97 Number Major Minor RaidDevice State 0 8 4 0 active sync /dev/sda4 1 8 20 1 active sync /dev/sdb4 /dev/md3: Version : 0.90 Creation Time : Wed Jul 15 08:36:18 2009 Raid Level : raid1 Array Size : 987904 (964.91 MiB 1011.61 MB) Used Dev Size : 987904 (964.91 MiB 1011.61 MB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 3 Persistence : Superblock is persistent Update Time : Fri Nov 1 13:26:33 2013 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 UUID : 3f4099f2:72e6171b:5ba962fd:48464a62 Events : 0.54 Number Major Minor RaidDevice State 0 8 3 0 active sync /dev/sda3 1 8 19 1 active sync /dev/sdb3 mdadm: md device /dev/md4 does not appear to be active. mdadm: md device /dev/md5 does not appear to be active. mdadm: md device /dev/md6 does not appear to be active. mdadm: md device /dev/md7 does not appear to be active. mdadm: md device /dev/md8 does not appear to be active. ~ # cat /etc/mtab securityfs /sys/kernel/security securityfs rw 0 0 /dev/md2 /DataVolume xfs rw,usrquota 0 0 /dev/md4 /ExtendVolume xfs rw,usrquota 0 0 ~ # df -k Filesystem 1k-blocks Used Available Use% Mounted on /dev/md0 1929044 145092 1685960 8% / /dev/md3 972344 123452 799500 13% /var /dev/ram0 63412 20 63392 0% /mnt/ram ~ # mdadm -D /dev/md2 /dev/md2: Version : 0.90 Creation Time : Sat Sep 25 10:01:26 2010 Raid Level : raid0 Array Size : 1947045760 (1856.85 GiB 1993.77 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 2 Persistence : Superblock is persistent Update Time : Fri Nov 1 13:30:53 2013 State : active Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Chunk Size : 64K UUID : 01dae60a:6831077b:77f74530:8680c183 Events : 0.97 Number Major Minor RaidDevice State 0 8 4 0 active sync /dev/sda4 1 8 20 1 active sync /dev/sdb4 ~ # mdadm -D /dev/md4 mdadm: md device /dev/md4 does not appear to be active. ~ # mount /dev/root on / type ext3 (rw,noatime,data=ordered) proc on /proc type proc (rw) sys on /sys type sysfs (rw) /dev/pts on /dev/pts type devpts (rw) securityfs on /sys/kernel/security type securityfs (rw) /dev/md3 on /var type ext3 (rw,noatime,data=ordered) /dev/ram0 on /mnt/ram type tmpfs (rw) ~ # cat /var/log/messages Oct 29 18:04:50 shmotashNAS daemon.warn wixEvent[3462]: Network Link - NIC 1 link is down. Oct 29 18:04:59 shmotashNAS daemon.info wixEvent[3462]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 29 18:04:59 shmotashNAS daemon.info wixEvent[3462]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 29 18:17:45 shmotashNAS daemon.warn wixEvent[3462]: Network Link - NIC 1 link is down. Oct 29 18:17:53 shmotashNAS daemon.info wixEvent[3462]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 29 18:17:53 shmotashNAS daemon.info wixEvent[3462]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 00:50:11 shmotashNAS daemon.warn wixEvent[3462]: Network Link - NIC 1 link is down. Oct 30 00:50:19 shmotashNAS daemon.info wixEvent[3462]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 00:50:19 shmotashNAS daemon.info wixEvent[3462]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 16:29:47 shmotashNAS daemon.warn wixEvent[3462]: Network Link - NIC 1 link is down. Oct 30 16:30:00 shmotashNAS daemon.info wixEvent[3462]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 16:30:00 shmotashNAS daemon.info wixEvent[3462]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 18:27:22 shmotashNAS daemon.warn wixEvent[3462]: Network Link - NIC 1 link is down. Oct 30 18:27:30 shmotashNAS daemon.info wixEvent[3462]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 18:27:30 shmotashNAS daemon.info wixEvent[3462]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 19:06:03 shmotashNAS daemon.warn wixEvent[3462]: Network Link - NIC 1 link is down. Oct 30 19:06:10 shmotashNAS daemon.info wixEvent[3462]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 19:06:10 shmotashNAS daemon.info wixEvent[3462]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 19:14:58 shmotashNAS daemon.warn wixEvent[3462]: Media Server - Media Server cannot find the path to one or more of the default folders: /Public/Shared Music, /Public/Shared Pictures or /Public/Shared Videos. Please verify that these folders have not been removed or that the names have not been changed. Oct 30 19:20:05 shmotashNAS daemon.alert wixEvent[3462]: Thermal Alarm - System temperature exceeded threshold.(66 degrees) Oct 30 19:58:29 shmotashNAS daemon.alert wixEvent[3462]: HDD SMART - HDD 1 SMART Health Status: Failed. Oct 30 22:05:39 shmotashNAS daemon.info init: Starting pid 13043, console /dev/null: '/usr/bin/killall' Oct 30 22:05:39 shmotashNAS syslog.info System log daemon exiting. Oct 30 22:08:09 shmotashNAS syslog.info syslogd started: BusyBox v1.1.1 Oct 30 22:08:09 shmotashNAS daemon.warn wixEvent[3557]: Network Link - NIC 1 link is down. Oct 30 22:08:19 shmotashNAS daemon.info wixEvent[3557]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 22:08:25 shmotashNAS daemon.warn wixEvent[3557]: Network Link - NIC 1 link is down. Oct 30 22:08:37 shmotashNAS daemon.info wixEvent[3557]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 22:08:44 shmotashNAS daemon.warn wixEvent[3557]: Network Link - NIC 1 link is down. Oct 30 22:08:46 shmotashNAS syslog.info miocrawler: +++++++++++++++ START OF ./miocrawler at 2013:10:30 - 22:08:46 [Version 01.09.00.96] ++++++++++++++ Oct 30 22:08:46 shmotashNAS syslog.info miocrawler: mc_db_init ... Oct 30 22:08:46 shmotashNAS syslog.info miocrawler: ****** database does not exist. ret = -1, creating path Oct 30 22:08:49 shmotashNAS syslog.info miocrawler: === mc_db_init ...Done. Oct 30 22:08:50 shmotashNAS syslog.info miocrawler: mcUtilsInit() Creating free queue pool Oct 30 22:08:51 shmotashNAS syslog.info miocrawler: === mcUtilsInit() Done. Oct 30 22:08:51 shmotashNAS syslog.info miocrawler: === inotify init done. Oct 30 22:08:51 shmotashNAS syslog.info miocrawler: mc_trans_updater_init() ... Oct 30 22:08:52 shmotashNAS syslog.info miocrawler: === mc_trans_updater_init() ...Done. Oct 30 22:08:52 shmotashNAS syslog.info miocrawler: === Walking directory done. Oct 30 22:08:57 shmotashNAS daemon.info wixEvent[3557]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 22:08:57 shmotashNAS daemon.info wixEvent[3557]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 22:08:57 shmotashNAS daemon.info wixEvent[3557]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 22:08:57 shmotashNAS daemon.info wixEvent[3557]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 22:09:10 shmotashNAS daemon.info init: Starting pid 4605, console /dev/null: '/bin/touch' Oct 30 22:09:10 shmotashNAS daemon.info init: Starting pid 4607, console /dev/ttyS0: '/sbin/getty' Oct 30 22:09:10 shmotashNAS daemon.info wixEvent[3557]: System Startup - System startup. Oct 30 22:09:16 shmotashNAS daemon.warn wixEvent[3557]: Media Server - Media Server cannot find the path to one or more of the default folders: /Public/Shared Music, /Public/Shared Pictures or /Public/Shared Videos. Please verify that these folders have not been removed or that the names have not been changed. Oct 30 22:14:14 shmotashNAS daemon.warn wixEvent[3557]: Network Link - NIC 1 link is down. Oct 30 22:14:21 shmotashNAS daemon.info wixEvent[3557]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 22:14:21 shmotashNAS daemon.info wixEvent[3557]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 22:29:36 shmotashNAS daemon.warn wixEvent[3557]: System Reboot - System will reboot. Oct 30 22:29:40 shmotashNAS daemon.info init: Starting pid 5974, console /dev/null: '/usr/bin/killall' Oct 30 22:29:40 shmotashNAS syslog.info System log daemon exiting. Oct 30 22:47:56 shmotashNAS syslog.info syslogd started: BusyBox v1.1.1 Oct 30 22:47:56 shmotashNAS daemon.warn wixEvent[3461]: Network Link - NIC 1 link is down. Oct 30 22:48:02 shmotashNAS daemon.info wixEvent[3461]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 22:48:02 shmotashNAS daemon.info wixEvent[3461]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 22:48:09 shmotashNAS syslog.info miocrawler: +++++++++++++++ START OF ./miocrawler at 2013:10:30 - 22:48:09 [Version 01.09.00.96] ++++++++++++++ Oct 30 22:48:09 shmotashNAS syslog.info miocrawler: mc_db_init ... Oct 30 22:48:09 shmotashNAS syslog.info miocrawler: ++++++++ database exists: ret = 0 Oct 30 22:48:10 shmotashNAS syslog.info miocrawler: === mc_db_init ...Done. Oct 30 22:48:10 shmotashNAS syslog.info miocrawler: mcUtilsInit() Creating free queue pool Oct 30 22:48:11 shmotashNAS syslog.info miocrawler: === mcUtilsInit() Done. Oct 30 22:48:11 shmotashNAS syslog.info miocrawler: === inotify init done. Oct 30 22:48:11 shmotashNAS syslog.info miocrawler: mc_trans_updater_init() ... Oct 30 22:48:11 shmotashNAS syslog.info miocrawler: === mc_trans_updater_init() ...Done. Oct 30 22:48:11 shmotashNAS syslog.info miocrawler: === Walking directory done. Oct 30 22:48:27 shmotashNAS daemon.info init: Starting pid 4079, console /dev/null: '/bin/touch' Oct 30 22:48:27 shmotashNAS daemon.info init: Starting pid 4080, console /dev/ttyS0: '/sbin/getty' Oct 30 22:48:28 shmotashNAS daemon.info wixEvent[3461]: System Startup - System startup. Oct 30 22:49:01 shmotashNAS daemon.warn wixEvent[3461]: Media Server - Media Server cannot find the path to one or more of the default folders: /Public/Shared Music, /Public/Shared Pictures or /Public/Shared Videos. Please verify that these folders have not been removed or that the names have not been changed. Oct 30 23:51:11 shmotashNAS daemon.warn wixEvent[3461]: System Reboot - System will reboot. Oct 30 23:51:16 shmotashNAS daemon.info init: Starting pid 6498, console /dev/null: '/usr/bin/killall' Oct 30 23:51:16 shmotashNAS syslog.info System log daemon exiting. Oct 30 23:54:19 shmotashNAS syslog.info syslogd started: BusyBox v1.1.1 Oct 30 23:55:37 shmotashNAS daemon.info wixEvent[3476]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 30 23:55:37 shmotashNAS daemon.info wixEvent[3476]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 30 23:55:44 shmotashNAS syslog.info miocrawler: +++++++++++++++ START OF ./miocrawler at 2013:10:30 - 23:55:44 [Version 01.09.00.96] ++++++++++++++ Oct 30 23:55:44 shmotashNAS syslog.info miocrawler: mc_db_init ... Oct 30 23:55:44 shmotashNAS syslog.info miocrawler: ++++++++ database exists: ret = 0 Oct 30 23:55:45 shmotashNAS syslog.info miocrawler: === mc_db_init ...Done. Oct 30 23:55:45 shmotashNAS syslog.info miocrawler: mcUtilsInit() Creating free queue pool Oct 30 23:55:46 shmotashNAS syslog.info miocrawler: === mcUtilsInit() Done. Oct 30 23:55:46 shmotashNAS syslog.info miocrawler: === inotify init done. Oct 30 23:55:46 shmotashNAS syslog.info miocrawler: mc_trans_updater_init() ... Oct 30 23:55:46 shmotashNAS syslog.info miocrawler: === mc_trans_updater_init() ...Done. Oct 30 23:55:46 shmotashNAS syslog.info miocrawler: === Walking directory done. Oct 30 23:55:58 shmotashNAS daemon.info init: Starting pid 4115, console /dev/null: '/bin/touch' Oct 30 23:55:58 shmotashNAS daemon.info init: Starting pid 4116, console /dev/ttyS0: '/sbin/getty' Oct 30 23:55:58 shmotashNAS daemon.info wixEvent[3476]: System Startup - System startup. Oct 30 23:56:33 shmotashNAS daemon.warn wixEvent[3476]: Media Server - Media Server cannot find the path to one or more of the default folders: /Public/Shared Music, /Public/Shared Pictures or /Public/Shared Videos. Please verify that these folders have not been removed or that the names have not been changed. Oct 31 00:29:14 shmotashNAS auth.info sshd[5409]: Server listening on 0.0.0.0 port 22. Oct 31 00:31:25 shmotashNAS auth.info sshd[5486]: Accepted password for root from 192.168.1.100 port 50785 ssh2 Oct 31 00:33:44 shmotashNAS auth.info sshd[5565]: Accepted password for root from 192.168.1.100 port 50817 ssh2 Oct 31 00:36:39 shmotashNAS daemon.info init: Starting pid 5680, console /dev/null: '/usr/bin/killall' Oct 31 00:36:39 shmotashNAS syslog.info System log daemon exiting. Oct 31 00:40:44 shmotashNAS syslog.info syslogd started: BusyBox v1.1.1 Oct 31 00:40:51 shmotashNAS daemon.info wixEvent[3464]: Network Link - NIC 1 link is up 100 Mbps full duplex. Oct 31 00:40:51 shmotashNAS daemon.info wixEvent[3464]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Oct 31 00:41:00 shmotashNAS syslog.info miocrawler: +++++++++++++++ START OF ./miocrawler at 2013:10:31 - 00:41:00 [Version 01.09.00.96] ++++++++++++++ Oct 31 00:41:00 shmotashNAS syslog.info miocrawler: mc_db_init ... Oct 31 00:41:00 shmotashNAS syslog.info miocrawler: ++++++++ database exists: ret = 0 Oct 31 00:41:00 shmotashNAS syslog.info miocrawler: === mc_db_init ...Done. Oct 31 00:41:01 shmotashNAS syslog.info miocrawler: mcUtilsInit() Creating free queue pool Oct 31 00:41:02 shmotashNAS syslog.info miocrawler: === mcUtilsInit() Done. Oct 31 00:41:02 shmotashNAS syslog.info miocrawler: === inotify init done. Oct 31 00:41:02 shmotashNAS syslog.info miocrawler: mc_trans_updater_init() ... Oct 31 00:41:02 shmotashNAS syslog.info miocrawler: === mc_trans_updater_init() ...Done. Oct 31 00:41:02 shmotashNAS syslog.info miocrawler: === Walking directory done. Oct 31 00:41:14 shmotashNAS daemon.info init: Starting pid 4101, console /dev/null: '/bin/touch' Oct 31 00:41:14 shmotashNAS daemon.info init: Starting pid 4102, console /dev/ttyS0: '/sbin/getty' Oct 31 00:41:15 shmotashNAS daemon.info wixEvent[3464]: System Startup - System startup. Oct 31 00:41:47 shmotashNAS daemon.warn wixEvent[3464]: Media Server - Media Server cannot find the path to one or more of the default folders: /Public/Shared Music, /Public/Shared Pictures or /Public/Shared Videos. Please verify that these folders have not been removed or that the names have not been changed. Oct 31 01:13:19 shmotashNAS daemon.info init: Starting pid 5385, console /dev/null: '/usr/bin/killall' Oct 31 01:13:19 shmotashNAS syslog.info System log daemon exiting. Nov 1 13:26:25 shmotashNAS syslog.info syslogd started: BusyBox v1.1.1 Nov 1 13:26:32 shmotashNAS daemon.info wixEvent[3471]: Network Link - NIC 1 link is up 100 Mbps full duplex. Nov 1 13:26:32 shmotashNAS daemon.info wixEvent[3471]: Network IP Address - NIC 1 use static IP address 192.168.1.102 Nov 1 13:26:38 shmotashNAS syslog.info miocrawler: +++++++++++++++ START OF ./miocrawler at 2013:11:01 - 13:26:38 [Version 01.09.00.96] ++++++++++++++ Nov 1 13:26:38 shmotashNAS syslog.info miocrawler: mc_db_init ... Nov 1 13:26:38 shmotashNAS syslog.info miocrawler: ++++++++ database exists: ret = 0 Nov 1 13:26:39 shmotashNAS syslog.info miocrawler: === mc_db_init ...Done. Nov 1 13:26:39 shmotashNAS syslog.info miocrawler: mcUtilsInit() Creating free queue pool Nov 1 13:26:40 shmotashNAS syslog.info miocrawler: === mcUtilsInit() Done. Nov 1 13:26:40 shmotashNAS syslog.info miocrawler: === inotify init done. Nov 1 13:26:40 shmotashNAS syslog.info miocrawler: mc_trans_updater_init() ... Nov 1 13:26:40 shmotashNAS syslog.info miocrawler: === mc_trans_updater_init() ...Done. Nov 1 13:26:40 shmotashNAS syslog.info miocrawler: === Walking directory done. Nov 1 13:26:52 shmotashNAS daemon.info init: Starting pid 4078, console /dev/null: '/bin/touch' Nov 1 13:26:52 shmotashNAS daemon.info init: Starting pid 4079, console /dev/ttyS0: '/sbin/getty' Nov 1 13:26:52 shmotashNAS daemon.info wixEvent[3471]: System Startup - System startup. Nov 1 13:27:28 shmotashNAS daemon.warn wixEvent[3471]: Media Server - Media Server cannot find the path to one or more of the default folders: /Public/Shared Music, /Public/Shared Pictures or /Public/Shared Videos. Please verify that these folders have not been removed or that the names have not been changed. Nov 1 13:44:48 shmotashNAS auth.info sshd[5375]: Accepted password for root from 192.168.1.103 port 50217 ssh2 Nov 1 13:51:08 shmotashNAS auth.info sshd[5894]: Accepted password for root from 192.168.1.103 port 50380 ssh2

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  • SQL SERVER – Shrinking Database is Bad – Increases Fragmentation – Reduces Performance

    - by pinaldave
    Earlier, I had written two articles related to Shrinking Database. I wrote about why Shrinking Database is not good. SQL SERVER – SHRINKDATABASE For Every Database in the SQL Server SQL SERVER – What the Business Says Is Not What the Business Wants I received many comments on Why Database Shrinking is bad. Today we will go over a very interesting example that I have created for the same. Here are the quick steps of the example. Create a test database Create two tables and populate with data Check the size of both the tables Size of database is very low Check the Fragmentation of one table Fragmentation will be very low Truncate another table Check the size of the table Check the fragmentation of the one table Fragmentation will be very low SHRINK Database Check the size of the table Check the fragmentation of the one table Fragmentation will be very HIGH REBUILD index on one table Check the size of the table Size of database is very HIGH Check the fragmentation of the one table Fragmentation will be very low Here is the script for the same. USE MASTER GO CREATE DATABASE ShrinkIsBed GO USE ShrinkIsBed GO -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Create FirstTable CREATE TABLE FirstTable (ID INT, FirstName VARCHAR(100), LastName VARCHAR(100), City VARCHAR(100)) GO -- Create Clustered Index on ID CREATE CLUSTERED INDEX [IX_FirstTable_ID] ON FirstTable ( [ID] ASC ) ON [PRIMARY] GO -- Create SecondTable CREATE TABLE SecondTable (ID INT, FirstName VARCHAR(100), LastName VARCHAR(100), City VARCHAR(100)) GO -- Create Clustered Index on ID CREATE CLUSTERED INDEX [IX_SecondTable_ID] ON SecondTable ( [ID] ASC ) ON [PRIMARY] GO -- Insert One Hundred Thousand Records INSERT INTO FirstTable (ID,FirstName,LastName,City) SELECT TOP 100000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Insert One Hundred Thousand Records INSERT INTO SecondTable (ID,FirstName,LastName,City) SELECT TOP 100000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Check Fragmentations in the database SELECT avg_fragmentation_in_percent, fragment_count FROM sys.dm_db_index_physical_stats (DB_ID(), OBJECT_ID('SecondTable'), NULL, NULL, 'LIMITED') GO Let us check the table size and fragmentation. Now let us TRUNCATE the table and check the size and Fragmentation. USE MASTER GO CREATE DATABASE ShrinkIsBed GO USE ShrinkIsBed GO -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Create FirstTable CREATE TABLE FirstTable (ID INT, FirstName VARCHAR(100), LastName VARCHAR(100), City VARCHAR(100)) GO -- Create Clustered Index on ID CREATE CLUSTERED INDEX [IX_FirstTable_ID] ON FirstTable ( [ID] ASC ) ON [PRIMARY] GO -- Create SecondTable CREATE TABLE SecondTable (ID INT, FirstName VARCHAR(100), LastName VARCHAR(100), City VARCHAR(100)) GO -- Create Clustered Index on ID CREATE CLUSTERED INDEX [IX_SecondTable_ID] ON SecondTable ( [ID] ASC ) ON [PRIMARY] GO -- Insert One Hundred Thousand Records INSERT INTO FirstTable (ID,FirstName,LastName,City) SELECT TOP 100000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Insert One Hundred Thousand Records INSERT INTO SecondTable (ID,FirstName,LastName,City) SELECT TOP 100000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Check Fragmentations in the database SELECT avg_fragmentation_in_percent, fragment_count FROM sys.dm_db_index_physical_stats (DB_ID(), OBJECT_ID('SecondTable'), NULL, NULL, 'LIMITED') GO You can clearly see that after TRUNCATE, the size of the database is not reduced and it is still the same as before TRUNCATE operation. After the Shrinking database operation, we were able to reduce the size of the database. If you notice the fragmentation, it is considerably high. The major problem with the Shrink operation is that it increases fragmentation of the database to very high value. Higher fragmentation reduces the performance of the database as reading from that particular table becomes very expensive. One of the ways to reduce the fragmentation is to rebuild index on the database. Let us rebuild the index and observe fragmentation and database size. -- Rebuild Index on FirstTable ALTER INDEX IX_SecondTable_ID ON SecondTable REBUILD GO -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Check Fragmentations in the database SELECT avg_fragmentation_in_percent, fragment_count FROM sys.dm_db_index_physical_stats (DB_ID(), OBJECT_ID('SecondTable'), NULL, NULL, 'LIMITED') GO You can notice that after rebuilding, Fragmentation reduces to a very low value (almost same to original value); however the database size increases way higher than the original. Before rebuilding, the size of the database was 5 MB, and after rebuilding, it is around 20 MB. Regular rebuilding the index is rebuild in the same user database where the index is placed. This usually increases the size of the database. Look at irony of the Shrinking database. One person shrinks the database to gain space (thinking it will help performance), which leads to increase in fragmentation (reducing performance). To reduce the fragmentation, one rebuilds index, which leads to size of the database to increase way more than the original size of the database (before shrinking). Well, by Shrinking, one did not gain what he was looking for usually. Rebuild indexing is not the best suggestion as that will create database grow again. I have always remembered the excellent post from Paul Randal regarding Shrinking the database is bad. I suggest every one to read that for accuracy and interesting conversation. Let us run following script where we Shrink the database and REORGANIZE. -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Check Fragmentations in the database SELECT avg_fragmentation_in_percent, fragment_count FROM sys.dm_db_index_physical_stats (DB_ID(), OBJECT_ID('SecondTable'), NULL, NULL, 'LIMITED') GO -- Shrink the Database DBCC SHRINKDATABASE (ShrinkIsBed); GO -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Check Fragmentations in the database SELECT avg_fragmentation_in_percent, fragment_count FROM sys.dm_db_index_physical_stats (DB_ID(), OBJECT_ID('SecondTable'), NULL, NULL, 'LIMITED') GO -- Rebuild Index on FirstTable ALTER INDEX IX_SecondTable_ID ON SecondTable REORGANIZE GO -- Name of the Database and Size SELECT name, (size*8) Size_KB FROM sys.database_files GO -- Check Fragmentations in the database SELECT avg_fragmentation_in_percent, fragment_count FROM sys.dm_db_index_physical_stats (DB_ID(), OBJECT_ID('SecondTable'), NULL, NULL, 'LIMITED') GO You can see that REORGANIZE does not increase the size of the database or remove the fragmentation. Again, I no way suggest that REORGANIZE is the solution over here. This is purely observation using demo. Read the blog post of Paul Randal. Following script will clean up the database -- Clean up USE MASTER GO ALTER DATABASE ShrinkIsBed SET SINGLE_USER WITH ROLLBACK IMMEDIATE GO DROP DATABASE ShrinkIsBed GO There are few valid cases of the Shrinking database as well, but that is not covered in this blog post. We will cover that area some other time in future. Additionally, one can rebuild index in the tempdb as well, and we will also talk about the same in future. Brent has written a good summary blog post as well. Are you Shrinking your database? Well, when are you going to stop Shrinking it? Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • Dynamic Code for type casting Generic Types 'generically' in C#

    - by Rick Strahl
    C# is a strongly typed language and while that's a fundamental feature of the language there are more and more situations where dynamic types make a lot of sense. I've written quite a bit about how I use dynamic for creating new type extensions: Dynamic Types and DynamicObject References in C# Creating a dynamic, extensible C# Expando Object Creating a dynamic DataReader for dynamic Property Access Today I want to point out an example of a much simpler usage for dynamic that I use occasionally to get around potential static typing issues in C# code especially those concerning generic types. TypeCasting Generics Generic types have been around since .NET 2.0 I've run into a number of situations in the past - especially with generic types that don't implement specific interfaces that can be cast to - where I've been unable to properly cast an object when it's passed to a method or assigned to a property. Granted often this can be a sign of bad design, but in at least some situations the code that needs to be integrated is not under my control so I have to make due with what's available or the parent object is too complex or intermingled to be easily refactored to a new usage scenario. Here's an example that I ran into in my own RazorHosting library - so I have really no excuse, but I also don't see another clean way around it in this case. A Generic Example Imagine I've implemented a generic type like this: public class RazorEngine<TBaseTemplateType> where TBaseTemplateType : RazorTemplateBase, new() You can now happily instantiate new generic versions of this type with custom template bases or even a non-generic version which is implemented like this: public class RazorEngine : RazorEngine<RazorTemplateBase> { public RazorEngine() : base() { } } To instantiate one: var engine = new RazorEngine<MyCustomRazorTemplate>(); Now imagine that the template class receives a reference to the engine when it's instantiated. This code is fired as part of the Engine pipeline when it gets ready to execute the template. It instantiates the template and assigns itself to the template: var template = new TBaseTemplateType() { Engine = this } The problem here is that possibly many variations of RazorEngine<T> can be passed. I can have RazorTemplateBase, RazorFolderHostTemplateBase, CustomRazorTemplateBase etc. as generic parameters and the Engine property has to reflect that somehow. So, how would I cast that? My first inclination was to use an interface on the engine class and then cast to the interface.  Generally that works, but unfortunately here the engine class is generic and has a few members that require the template type in the member signatures. So while I certainly can implement an interface: public interface IRazorEngine<TBaseTemplateType> it doesn't really help for passing this generically templated object to the template class - I still can't cast it if multiple differently typed versions of the generic type could be passed. I have the exact same issue in that I can't specify a 'generic' generic parameter, since there's no underlying base type that's common. In light of this I decided on using object and the following syntax for the property (and the same would be true for a method parameter): public class RazorTemplateBase :MarshalByRefObject,IDisposable { public object Engine {get;set; } } Now because the Engine property is a non-typed object, when I need to do something with this value, I still have no way to cast it explicitly. What I really would need is: public RazorEngine<> Engine { get; set; } but that's not possible. Dynamic to the Rescue Luckily with the dynamic type this sort of thing can be mitigated fairly easily. For example here's a method that uses the Engine property and uses the well known class interface by simply casting the plain object reference to dynamic and then firing away on the properties and methods of the base template class that are common to all templates:/// <summary> /// Allows rendering a dynamic template from a string template /// passing in a model. This is like rendering a partial /// but providing the input as a /// </summary> public virtual string RenderTemplate(string template,object model) { if (template == null) return string.Empty; // if there's no template markup if(!template.Contains("@")) return template; // use dynamic to get around generic type casting dynamic engine = Engine; string result = engine.RenderTemplate(template, model); if (result == null) throw new ApplicationException("RenderTemplate failed: " + engine.ErrorMessage); return result; } Prior to .NET 4.0  I would have had to use Reflection for this sort of thing which would have a been a heck of a lot more verbose, but dynamic makes this so much easier and cleaner and in this case at least the overhead is negliable since it's a single dynamic operation on an otherwise very complex operation call. Dynamic as  a Bailout Sometimes this sort of thing often reeks of a design flaw, and I agree that in hindsight this could have been designed differently. But as is often the case this particular scenario wasn't planned for originally and removing the generic signatures from the base type would break a ton of other code in the framework. Given the existing fairly complex engine design, refactoring an interface to remove generic types just to make this particular code work would have been overkill. Instead dynamic provides a nice and simple and relatively clean solution. Now if there were many other places where this occurs I would probably consider reworking the code to make this cleaner but given this isolated instance and relatively low profile operation use of dynamic seems a valid choice for me. This solution really works anywhere where you might end up with an inheritance structure that doesn't have a common base or interface that is sufficient. In the example above I know what I'm getting but there's no common base type that I can cast to. All that said, it's a good idea to think about use of dynamic before you rush in. In many situations there are alternatives that can still work with static typing. Dynamic definitely has some overhead compared to direct static access of objects, so if possible we should definitely stick to static typing. In the example above the application already uses dynamics extensively for dynamic page page templating and passing models around so introducing dynamics here has very little additional overhead. The operation itself also fires of a fairly resource heavy operation where the overhead of a couple of dynamic member accesses are not a performance issue. So, what's your experience with dynamic as a bailout mechanism? © Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • C#/.NET Little Wonders: The Timeout static class

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. When I started the “Little Wonders” series, I really wanted to pay homage to parts of the .NET Framework that are often small but can help in big ways.  The item I have to discuss today really is a very small item in the .NET BCL, but once again I feel it can help make the intention of code much clearer and thus is worthy of note. The Problem - Magic numbers aren’t very readable or maintainable In my first Little Wonders Post (Five Little Wonders That Make Code Better) I mention the TimeSpan factory methods which, I feel, really help the readability of constructed TimeSpan instances. Just to quickly recap that discussion, ask yourself what the TimeSpan specified in each case below is 1: // Five minutes? Five Seconds? 2: var fiveWhat1 = new TimeSpan(0, 0, 5); 3: var fiveWhat2 = new TimeSpan(0, 0, 5, 0); 4: var fiveWhat3 = new TimeSpan(0, 0, 5, 0, 0); You’d think they’d all be the same unit of time, right?  After all, most overloads tend to tack additional arguments on the end.  But this is not the case with TimeSpan, where the constructor forms are:     TimeSpan(int hours, int minutes, int seconds);     TimeSpan(int days, int hours, int minutes, int seconds);     TimeSpan(int days, int hours, int minutes, int seconds, int milliseconds); Notice how in the 4 and 5 parameter version we suddenly have the parameter days slipping in front of hours?  This can make reading constructors like those above much harder.  Fortunately, there are TimeSpan factory methods to help make your intention crystal clear: 1: // Ah! Much clearer! 2: var fiveSeconds = TimeSpan.FromSeconds(5); These are great because they remove all ambiguity from the reader!  So in short, magic numbers in constructors and methods can be ambiguous, and anything we can do to clean up the intention of the developer will make the code much easier to read and maintain. Timeout – Readable identifiers for infinite timeout values In a similar way to TimeSpan, let’s consider specifying timeouts for some of .NET’s (or our own) many methods that allow you to specify timeout periods. For example, in the TPL Task class, there is a family of Wait() methods that can take TimeSpan or int for timeouts.  Typically, if you want to specify an infinite timeout, you’d just call the version that doesn’t take a timeout parameter at all: 1: myTask.Wait(); // infinite wait But there are versions that take the int or TimeSpan for timeout as well: 1: // Wait for 100 ms 2: myTask.Wait(100); 3:  4: // Wait for 5 seconds 5: myTask.Wait(TimeSpan.FromSeconds(5); Now, if we want to specify an infinite timeout to wait on the Task, we could pass –1 (or a TimeSpan set to –1 ms), which what the .NET BCL methods with timeouts use to represent an infinite timeout: 1: // Also infinite timeouts, but harder to read/maintain 2: myTask.Wait(-1); 3: myTask.Wait(TimeSpan.FromMilliseconds(-1)); However, these are not as readable or maintainable.  If you were writing this code, you might make the mistake of thinking 0 or int.MaxValue was an infinite timeout, and you’d be incorrect.  Also, reading the code above it isn’t as clear that –1 is infinite unless you happen to know that is the specified behavior. To make the code like this easier to read and maintain, there is a static class called Timeout in the System.Threading namespace which contains definition for infinite timeouts specified as both int and TimeSpan forms: Timeout.Infinite An integer constant with a value of –1 Timeout.InfiniteTimeSpan A static readonly TimeSpan which represents –1 ms (only available in .NET 4.5+) This makes our calls to Task.Wait() (or any other calls with timeouts) much more clear: 1: // intention to wait indefinitely is quite clear now 2: myTask.Wait(Timeout.Infinite); 3: myTask.Wait(Timeout.InfiniteTimeSpan); But wait, you may say, why would we care at all?  Why not use the version of Wait() that takes no arguments?  Good question!  When you’re directly calling the method with an infinite timeout that’s what you’d most likely do, but what if you are just passing along a timeout specified by a caller from higher up?  Or perhaps storing a timeout value from a configuration file, and want to default it to infinite? For example, perhaps you are designing a communications module and want to be able to shutdown gracefully, but if you can’t gracefully finish in a specified amount of time you want to force the connection closed.  You could create a Shutdown() method in your class, and take a TimeSpan or an int for the amount of time to wait for a clean shutdown – perhaps waiting for client to acknowledge – before terminating the connection.  So, assume we had a pub/sub system with a class to broadcast messages: 1: // Some class to broadcast messages to connected clients 2: public class Broadcaster 3: { 4: // ... 5:  6: // Shutdown connection to clients, wait for ack back from clients 7: // until all acks received or timeout, whichever happens first 8: public void Shutdown(int timeout) 9: { 10: // Kick off a task here to send shutdown request to clients and wait 11: // for the task to finish below for the specified time... 12:  13: if (!shutdownTask.Wait(timeout)) 14: { 15: // If Wait() returns false, we timed out and task 16: // did not join in time. 17: } 18: } 19: } We could even add an overload to allow us to use TimeSpan instead of int, to give our callers the flexibility to specify timeouts either way: 1: // overload to allow them to specify Timeout in TimeSpan, would 2: // just call the int version passing in the TotalMilliseconds... 3: public void Shutdown(TimeSpan timeout) 4: { 5: Shutdown(timeout.TotalMilliseconds); 6: } Notice in case of this class, we don’t assume the caller wants infinite timeouts, we choose to rely on them to tell us how long to wait.  So now, if they choose an infinite timeout, they could use the –1, which is more cryptic, or use Timeout class to make the intention clear: 1: // shutdown the broadcaster, waiting until all clients ack back 2: // without timing out. 3: myBroadcaster.Shutdown(Timeout.Infinite); We could even add a default argument using the int parameter version so that specifying no arguments to Shutdown() assumes an infinite timeout: 1: // Modified original Shutdown() method to add a default of 2: // Timeout.Infinite, works because Timeout.Infinite is a compile 3: // time constant. 4: public void Shutdown(int timeout = Timeout.Infinite) 5: { 6: // same code as before 7: } Note that you can’t default the ShutDown(TimeSpan) overload with Timeout.InfiniteTimeSpan since it is not a compile-time constant.  The only acceptable default for a TimeSpan parameter would be default(TimeSpan) which is zero milliseconds, which specified no wait, not infinite wait. Summary While Timeout.Infinite and Timeout.InfiniteTimeSpan are not earth-shattering classes in terms of functionality, they do give you very handy and readable constant values that you can use in your programs to help increase readability and maintainability when specifying infinite timeouts for various timeouts in the BCL and your own applications. Technorati Tags: C#,CSharp,.NET,Little Wonders,Timeout,Task

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  • Lessons from rewriting POP Forums for MVC, open source-like

    - by Jeff
    It has been a ton of work, interrupted over the last two years by unemployment, moving, a baby, failing to sell houses and other life events, but it's really exciting to see POP Forums v9 coming together. I'm not even sure when I decided to really commit to it as an open source project, but working on the same team as the CodePlex folks probably had something to do with it. Moving along the roadmap I set for myself, the app is now running on a quasi-production site... we launched MouseZoom last weekend. (That's a post-beta 1 build of the forum. There's also some nifty Silverlight DeepZoom goodness on that site.)I have to make a point to illustrate just how important starting over was for me. I started this forum thing for my sites in old ASP more than ten years ago. What a mess that stuff was, including SQL injection vulnerabilities and all kinds of crap. It went to ASP.NET in 2002, but even then, it felt a little too much like script. More than a year later, in 2003, I did an honest to goodness rewrite. If you've been in this business of writing code for any amount of time, you know how much you hate what you wrote a month ago, so just imagine that with seven years in between. The subsequent versions still carried a fair amount of crap, and that's why I had to start over, to make a clean break. Mind you, much of that crap is still running on some of my production sites in a stable manner, but it's a pain in the ass to maintain.So with that clean break, there is much that I have learned. These are a few of those lessons, in no particular order...Avoid shiny object syndromeOver the years, I've embraced new things without bothering to ask myself why. I remember spending the better part of a year trying to adapt this app to use the membership and profile API's in ASP.NET, just because they were there. They didn't solve any known problem. Early on in this version, I dabbled in exotic ORM's, even though I already had the fundamental SQL that I knew worked. I bloated up the client side code with all kinds of jQuery UI and plugins just because, and it got in the way. All the new shiny can be distracting, and I've come to realize that I've allowed it to be a distraction most of my professional life.Just query what you needI've spent a lot of time over-thinking how to query data. In the SQL world, this means exotic joins, special caches, the read-update-commit loop of ORM's, etc. There are times when you have to remind yourself that you aren't Facebook, you'll never be Facebook, and that databases are in fact intended to serve data. In a lot of projects, back in the day, I used to have these big, rich data objects and pass them all over the place, through various application tiers, when in reality, all I needed was some ID from the entity. I try to be mindful of how many queries hit the database on a given request, but I don't obsess over it. I just get what I need.Don't spend too much time worrying about your unit testsIf you've looked at any of the tests for POP Forums, you might offer an audible WTF. That's OK. There's a whole lot of mocking going on. In some cases, it points out where you're doing too much, and that's good for improving your design. In other cases it shows where your design sucks. But the biggest trap of unit testing is that you worry it should be prettier. That's a waste of time. When you write a test, in many cases before the production code, the important part is that you're testing the right thing. If you have to mock up a bunch of stuff to test the outcome, so be it, but it's not wasted time. You're still doing up the typical arrange-action-assert deal, and you'll be able to read that later if you need to.Get back to your HTTP rootsASP.NET Webforms did a reasonably decent job at abstracting us away from the stateless nature of the Web. A lot of people criticize it, but I think it all worked pretty well. These days, with MVC, jQuery, REST services, and what not, we've gone back to thinking about the wire. The nuts and bolts passing between our Web browser and server matters. This doesn't make things harder, in my opinion, it makes them easier. There is something incredibly freeing about how we approach development of Web apps now. HTTP is a really simple protocol, and the stuff we push through it, in particular HTML and JSON, are pretty simple too. The debugging points are really easy to trap and trace.Premature optimization is prematureI'll go back to the data thing for a moment. I've been known to look at a particular action or use case and stress about the number of calls that are made to the database. I'm not suggesting that it's a bad thing to keep these in mind, but if you worry about it outside of the context of the actual impact, you're wasting time. For example, I query the database for last read times in a forum separately of the user and the list of forums. The impact on performance barely exists. If I put it under load, exceeding the kind of load I expect, it still barely has an impact. Then consider it only counts for logged in users. The context of this "inefficient" action is that it doesn't matter. Did I mention I won't be Facebook?Solve your own problems firstThis is another trap I've fallen into. I've often thought about what other people might need for some feature or aspect of the app. In other words, I was willing to make design decisions based on non-existent data. How stupid is that? When I decided to truly open source this thing, building for myself first was a stated design goal. This app has to server the audiences of CoasterBuzz, MouseZoom and other sites first. In this development scenario, you don't have access to mountains of usability studies or user focus groups. You have to start with what you know.I'm sure there are other points I could make too. It has been a lot of fun to work on, and I look forward to evolving the UI as time goes on. That's where I hope to see more magic in the future.

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  • Silverlight for Everyone!!

    - by subodhnpushpak
    Someone asked me to compare Silverlight / HTML development. I realized that the question can be answered in many ways: Below is the high level comparison between a HTML /JavaScript client and Silverlight client and why silverlight was chosen over HTML / JavaScript client (based on type of users and major functionalities provided): 1. For end users Browser compatibility Silverlight is a plug-in and requires installation first. However, it does provides consistent look and feel across all browsers. For HTML / DHTML, there is a need to tweak JavaScript for each of the browser supported. In fact, tags like <span> and <div> works differently on different browser / version. So, HTML works on most of the systems but also requires lot of efforts coding-wise to adhere to all standards/ browsers / versions. Out of browser support No support in HTML. Third party tools like  Google gears offers some functionalities but there are lots of issues around platform and accessibility. Out of box support for out-of-browser support. provides features like drag and drop onto application surface. Cut and copy paste in HTML HTML is displayed in browser; which, in turn provides facilities for cut copy and paste. Silverlight (specially 4) provides rich features for cut-copy-paste along with full control over what can be cut copy pasted by end users and .advanced features like visual tree printing. Rich user experience HTML can provide some rich experience by use of some JavaScript libraries like JQuery. However, extensive use of JavaScript combined with various versions of browsers and the supported JavaScript makes the solution cumbersome. Silverlight is meant for RIA experience. User data storage on client end In HTML only small amount of data can be stored that too in cookies. In Silverlight large data may be stored, that too in secure way. This increases the response time. Post back In HTML / JavaScript the post back can be stopped by use of AJAX. Extensive use of AJAX can be a bottleneck as browser stack is used for the calls. Both look and feel and data travel over network.                           In Silverlight everything run the client side. Calls are made to server ONLY for data; which also reduces network traffic in long run. 2. For Developers Coding effort HTML / JavaScript can take considerable amount to code if features (requirements) are rich. For AJAX like interfaces; knowledge of third party kits like DOJO / Yahoo UI / JQuery is required which has steep learning curve. ASP .Net coding world revolves mostly along <table> tags for alignments whereas most popular tools provide <div> tags; which requires lots of tweaking. AJAX calls can be a bottlenecks for performance, if the calls are many. In Silverlight; coding is in C#, which is managed code. XAML is also very intuitive and Blend can be used to provide look and feel. Event handling is much clean than in JavaScript. Provides for many clean patterns like MVVM and composable application. Each call to server is asynchronous in silverlight. AJAX is in built into silverlight. Threading can be done at the client side itself to provide for better responsiveness; etc. Debugging Debugging in HTML / JavaScript is difficult. As JavaScript is interpreted; there is NO compile time error handling. Debugging in Silverlight is very helpful. As it is compiled; it provides rich features for both compile time and run time error handling. Multi -targeting browsers HTML / JavaScript have different rendering behaviours in different browsers / and their versions. JavaScript have to be written to sublime the differences in browser behaviours. Silverlight works exactly the same in all browsers and works on almost all popular browser. Multi-targeting desktop No support in HTML / JavaScript Silverlight is very close to WPF. Bot the platform may be easily targeted while maintaining the same source code. Rich toolkit HTML /JavaScript have limited toolkit as controls Silverlight provides a rich set of controls including graphs, audio, video, layout, etc. 3. For Architects Design Patterns Silverlight provides for patterns like MVVM (MVC) and rich (fat)  client architecture. This segregates the "separation of concern" very clearly. Client (silverlight) does what it is expected to do and server does what it is expected of. In HTML / JavaScript world most of the processing is done on the server side. Extensibility Silverlight provides great deal of extensibility as custom controls may be made. Extensibility is NOT restricted by browser but by the plug-in silverlight runs in. HTML / JavaScript works in a certain way and extensibility is generally done on the server side rather than client end. Client side is restricted by the limitations of the browser. Performance Silverlight provides localized storage which may be used for cached data storage. this reduces the response time. As processing can be done on client side itself; there is no need for server round trips. this decreases the round about time. Look and feel of the application is downloaded ONLY initially, afterwards ONLY data is fetched form the server. Security Silverlight is compiled code downloaded as .XAP; As compared to HTML / JavaScript, it provides more secure sandboxed approach. Cross - scripting is inherently prohibited in silverlight by default. If proper guidelines are followed silverlight provides much robust security mechanism as against HTML / JavaScript world. For example; knowing server Address in obfuscated JavaScript is easier than a compressed compiled obfuscated silverlight .XAP file. Some of these like (offline and Canvas support) will be available in HTML5. However, the timelines are not encouraging at all. According to Ian Hickson, editor of the HTML5 specification, the specification to reach the W3C Candidate Recommendation stage during 2012, and W3C Recommendation in the year 2022 or later. see http://en.wikipedia.org/wiki/HTML5 for details. The above is MY opinion. I will love to hear yours; do let me know via comments. Technorati Tags: Silverlight

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  • Library like ENet, but for TCP?

    - by Milo
    I'm not looking to use boost::asio, it is overly complex for my needs. I'm building a game that is cross platform, for desktop, iPhone and Android. I found a library called ENet which is pretty much what I need, but it uses UDP which does not seem to support encryption and a few other things. Given that the game is an event driven card game, TCP seems like the right fit. However, all I have found is WINSOCK / berkley sockets and bost::asio. Here is a sample client server application with ENet: #include <enet/enet.h> #include <stdlib.h> #include <string> #include <iostream> class Host { ENetAddress address; ENetHost * server; ENetHost* client; ENetEvent event; public: Host() :server(NULL) { enet_initialize(); setupServer(); } void setupServer() { if(server) { enet_host_destroy(server); server = NULL; } address.host = ENET_HOST_ANY; /* Bind the server to port 1234. */ address.port = 1721; server = enet_host_create (& address /* the address to bind the server host to */, 32 /* allow up to 32 clients and/or outgoing connections */, 2 /* allow up to 2 channels to be used, 0 and 1 */, 0 /* assume any amount of incoming bandwidth */, 0 /* assume any amount of outgoing bandwidth */); } void daLoop() { while(true) { /* Wait up to 1000 milliseconds for an event. */ while (enet_host_service (server, & event, 5000) > 0) { ENetPacket * packet; switch (event.type) { case ENET_EVENT_TYPE_CONNECT: printf ("A new client connected from %x:%u.\n", event.peer -> address.host, event.peer -> address.port); /* Store any relevant client information here. */ event.peer -> data = "Client information"; /* Create a reliable packet of size 7 containing "packet\0" */ packet = enet_packet_create ("packet", strlen ("packet") + 1, ENET_PACKET_FLAG_RELIABLE); /* Extend the packet so and append the string "foo", so it now */ /* contains "packetfoo\0" */ enet_packet_resize (packet, strlen ("packetfoo") + 1); strcpy ((char*)& packet -> data [strlen ("packet")], "foo"); /* Send the packet to the peer over channel id 0. */ /* One could also broadcast the packet by */ /* enet_host_broadcast (host, 0, packet); */ enet_peer_send (event.peer, 0, packet); /* One could just use enet_host_service() instead. */ enet_host_flush (server); break; case ENET_EVENT_TYPE_RECEIVE: printf ("A packet of length %u containing %s was received from %s on channel %u.\n", event.packet -> dataLength, event.packet -> data, event.peer -> data, event.channelID); /* Clean up the packet now that we're done using it. */ enet_packet_destroy (event.packet); break; case ENET_EVENT_TYPE_DISCONNECT: printf ("%s disconected.\n", event.peer -> data); /* Reset the peer's client information. */ event.peer -> data = NULL; } } } } ~Host() { if(server) { enet_host_destroy(server); server = NULL; } atexit (enet_deinitialize); } }; class Client { ENetAddress address; ENetEvent event; ENetPeer *peer; ENetHost* client; public: Client() :peer(NULL) { enet_initialize(); setupPeer(); } void setupPeer() { client = enet_host_create (NULL /* create a client host */, 1 /* only allow 1 outgoing connection */, 2 /* allow up 2 channels to be used, 0 and 1 */, 57600 / 8 /* 56K modem with 56 Kbps downstream bandwidth */, 14400 / 8 /* 56K modem with 14 Kbps upstream bandwidth */); if (client == NULL) { fprintf (stderr, "An error occurred while trying to create an ENet client host.\n"); exit (EXIT_FAILURE); } /* Connect to some.server.net:1234. */ enet_address_set_host (& address, "192.168.2.13"); address.port = 1721; /* Initiate the connection, allocating the two channels 0 and 1. */ peer = enet_host_connect (client, & address, 2, 0); if (peer == NULL) { fprintf (stderr, "No available peers for initiating an ENet connection.\n"); exit (EXIT_FAILURE); } /* Wait up to 5 seconds for the connection attempt to succeed. */ if (enet_host_service (client, & event, 20000) > 0 && event.type == ENET_EVENT_TYPE_CONNECT) { std::cout << "Connection to some.server.net:1234 succeeded." << std::endl; } else { /* Either the 5 seconds are up or a disconnect event was */ /* received. Reset the peer in the event the 5 seconds */ /* had run out without any significant event. */ enet_peer_reset (peer); puts ("Connection to some.server.net:1234 failed."); } } void daLoop() { ENetPacket* packet; /* Create a reliable packet of size 7 containing "packet\0" */ packet = enet_packet_create ("backet", strlen ("backet") + 1, ENET_PACKET_FLAG_RELIABLE); /* Extend the packet so and append the string "foo", so it now */ /* contains "packetfoo\0" */ enet_packet_resize (packet, strlen ("backetfoo") + 1); strcpy ((char*)& packet -> data [strlen ("backet")], "foo"); /* Send the packet to the peer over channel id 0. */ /* One could also broadcast the packet by */ /* enet_host_broadcast (host, 0, packet); */ enet_peer_send (event.peer, 0, packet); /* One could just use enet_host_service() instead. */ enet_host_flush (client); while(true) { /* Wait up to 1000 milliseconds for an event. */ while (enet_host_service (client, & event, 1000) > 0) { ENetPacket * packet; switch (event.type) { case ENET_EVENT_TYPE_RECEIVE: printf ("A packet of length %u containing %s was received from %s on channel %u.\n", event.packet -> dataLength, event.packet -> data, event.peer -> data, event.channelID); /* Clean up the packet now that we're done using it. */ enet_packet_destroy (event.packet); break; } } } } ~Client() { atexit (enet_deinitialize); } }; int main() { std::string a; std::cin >> a; if(a == "host") { Host host; host.daLoop(); } else { Client c; c.daLoop(); } return 0; } I looked at some socket tutorials and they seemed a bit too low level. I just need something that abstracts away the platform (eg, no WINSOCKS) and that has basic ability to keep track of connected clients and send them messages. Thanks

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  • C# Performance Pitfall – Interop Scenarios Change the Rules

    - by Reed
    C# and .NET, overall, really do have fantastic performance in my opinion.  That being said, the performance characteristics dramatically differ from native programming, and take some relearning if you’re used to doing performance optimization in most other languages, especially C, C++, and similar.  However, there are times when revisiting tricks learned in native code play a critical role in performance optimization in C#. I recently ran across a nasty scenario that illustrated to me how dangerous following any fixed rules for optimization can be… The rules in C# when optimizing code are very different than C or C++.  Often, they’re exactly backwards.  For example, in C and C++, lifting a variable out of loops in order to avoid memory allocations often can have huge advantages.  If some function within a call graph is allocating memory dynamically, and that gets called in a loop, it can dramatically slow down a routine. This can be a tricky bottleneck to track down, even with a profiler.  Looking at the memory allocation graph is usually the key for spotting this routine, as it’s often “hidden” deep in call graph.  For example, while optimizing some of my scientific routines, I ran into a situation where I had a loop similar to: for (i=0; i<numberToProcess; ++i) { // Do some work ProcessElement(element[i]); } .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 loop was at a fairly high level in the call graph, and often could take many hours to complete, depending on the input data.  As such, any performance optimization we could achieve would be greatly appreciated by our users. After a fair bit of profiling, I noticed that a couple of function calls down the call graph (inside of ProcessElement), there was some code that effectively was doing: // Allocate some data required DataStructure* data = new DataStructure(num); // Call into a subroutine that passed around and manipulated this data highly CallSubroutine(data); // Read and use some values from here double values = data->Foo; // Cleanup delete data; // ... return bar; Normally, if “DataStructure” was a simple data type, I could just allocate it on the stack.  However, it’s constructor, internally, allocated it’s own memory using new, so this wouldn’t eliminate the problem.  In this case, however, I could change the call signatures to allow the pointer to the data structure to be passed into ProcessElement and through the call graph, allowing the inner routine to reuse the same “data” memory instead of allocating.  At the highest level, my code effectively changed to something like: DataStructure* data = new DataStructure(numberToProcess); for (i=0; i<numberToProcess; ++i) { // Do some work ProcessElement(element[i], data); } delete data; Granted, this dramatically reduced the maintainability of the code, so it wasn’t something I wanted to do unless there was a significant benefit.  In this case, after profiling the new version, I found that it increased the overall performance dramatically – my main test case went from 35 minutes runtime down to 21 minutes.  This was such a significant improvement, I felt it was worth the reduction in maintainability. In C and C++, it’s generally a good idea (for performance) to: Reduce the number of memory allocations as much as possible, Use fewer, larger memory allocations instead of many smaller ones, and Allocate as high up the call stack as possible, and reuse memory I’ve seen many people try to make similar optimizations in C# code.  For good or bad, this is typically not a good idea.  The garbage collector in .NET completely changes the rules here. In C#, reallocating memory in a loop is not always a bad idea.  In this scenario, for example, I may have been much better off leaving the original code alone.  The reason for this is the garbage collector.  The GC in .NET is incredibly effective, and leaving the allocation deep inside the call stack has some huge advantages.  First and foremost, it tends to make the code more maintainable – passing around object references tends to couple the methods together more than necessary, and overall increase the complexity of the code.  This is something that should be avoided unless there is a significant reason.  Second, (unlike C and C++) memory allocation of a single object in C# is normally cheap and fast.  Finally, and most critically, there is a large advantage to having short lived objects.  If you lift a variable out of the loop and reuse the memory, its much more likely that object will get promoted to Gen1 (or worse, Gen2).  This can cause expensive compaction operations to be required, and also lead to (at least temporary) memory fragmentation as well as more costly collections later. As such, I’ve found that it’s often (though not always) faster to leave memory allocations where you’d naturally place them – deep inside of the call graph, inside of the loops.  This causes the objects to stay very short lived, which in turn increases the efficiency of the garbage collector, and can dramatically improve the overall performance of the routine as a whole. In C#, I tend to: Keep variable declarations in the tightest scope possible Declare and allocate objects at usage While this tends to cause some of the same goals (reducing unnecessary allocations, etc), the goal here is a bit different – it’s about keeping the objects rooted for as little time as possible in order to (attempt) to keep them completely in Gen0, or worst case, Gen1.  It also has the huge advantage of keeping the code very maintainable – objects are used and “released” as soon as possible, which keeps the code very clean.  It does, however, often have the side effect of causing more allocations to occur, but keeping the objects rooted for a much shorter time. Now – nowhere here am I suggesting that these rules are hard, fast rules that are always true.  That being said, my time spent optimizing over the years encourages me to naturally write code that follows the above guidelines, then profile and adjust as necessary.  In my current project, however, I ran across one of those nasty little pitfalls that’s something to keep in mind – interop changes the rules. In this case, I was dealing with an API that, internally, used some COM objects.  In this case, these COM objects were leading to native allocations (most likely C++) occurring in a loop deep in my call graph.  Even though I was writing nice, clean managed code, the normal managed code rules for performance no longer apply.  After profiling to find the bottleneck in my code, I realized that my inner loop, a innocuous looking block of C# code, was effectively causing a set of native memory allocations in every iteration.  This required going back to a “native programming” mindset for optimization.  Lifting these variables and reusing them took a 1:10 routine down to 0:20 – again, a very worthwhile improvement. Overall, the lessons here are: Always profile if you suspect a performance problem – don’t assume any rule is correct, or any code is efficient just because it looks like it should be Remember to check memory allocations when profiling, not just CPU cycles Interop scenarios often cause managed code to act very differently than “normal” managed code. Native code can be hidden very cleverly inside of managed wrappers

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  • T4 Performance Counters explained

    - by user13346607
    Now that T4 is out for a few month some people might have wondered what details of the new pipeline you can monitor. A "cpustat -h" lists a lot of events that can be monitored, and only very few are self-explanatory. I will try to give some insight on all of them, some of these "PIC events" require an in-depth knowledge of T4 pipeline. Over time I will try to explain these, for the time being these events should simply be ignored. (Side note: some counters changed from tape-out 1.1 (*only* used in the T4 beta program) to tape-out 1.2 (used in the systems shipping today) The table only lists the tape-out 1.2 counters) 0 0 1 1058 6033 Oracle Microelectronics 50 14 7077 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} pic name (cpustat) Prose Comment Sel-pipe-drain-cycles, Sel-0-[wait|ready], Sel-[1,2] Sel-0-wait counts cycles a strand waits to be selected. Some reasons can be counted in detail; these are: Sel-0-ready: Cycles a strand was ready but not selected, that can signal pipeline oversubscription Sel-1: Cycles only one instruction or µop was selected Sel-2: Cycles two instructions or µops were selected Sel-pipe-drain-cycles: cf. PRM footnote 8 to table 10.2 Pick-any, Pick-[0|1|2|3] Cycles one, two, three, no or at least one instruction or µop is picked Instr_FGU_crypto Number of FGU or crypto instructions executed on that vcpu Instr_ld dto. for load Instr_st dto. for store SPR_ring_ops dto. for SPR ring ops Instr_other dto. for all other instructions not listed above, PRM footnote 7 to table 10.2 lists the instructions Instr_all total number of instructions executed on that vcpu Sw_count_intr Nr of S/W count instructions on that vcpu (sethi %hi(fc000),%g0 (whatever that is))  Atomics nr of atomic ops, which are LDSTUB/a, CASA/XA, and SWAP/A SW_prefetch Nr of PREFETCH or PREFETCHA instructions Block_ld_st Block loads or store on that vcpu IC_miss_nospec, IC_miss_[L2_or_L3|local|remote]\ _hit_nospec Various I$ misses, distinguished by where they hit. All of these count per thread, but only primary events: T4 counts only the first occurence of an I$ miss on a core for a certain instruction. If one strand misses in I$ this miss is counted, but if a second strand on the same core misses while the first miss is being resolved, that second miss is not counted This flavour of I$ misses counts only misses that are caused by instruction that really commit (note the "_nospec") BTC_miss Branch target cache miss ITLB_miss ITLB misses (synchronously counted) ITLB_miss_asynch dto. but asynchronously [I|D]TLB_fill_\ [8KB|64KB|4MB|256MB|2GB|trap] H/W tablewalk events that fill ITLB or DTLB with translation for the corresponding page size. The “_trap” event occurs if the HWTW was not able to fill the corresponding TLB IC_mtag_miss, IC_mtag_miss_\ [ptag_hit|ptag_miss|\ ptag_hit_way_mismatch] I$ micro tag misses, with some options for drill down Fetch-0, Fetch-0-all fetch-0 counts nr of cycles nothing was fetched for this particular strand, fetch-0-all counts cycles nothing was fetched for all strands on a core Instr_buffer_full Cycles the instruction buffer for a strand was full, thereby preventing any fetch BTC_targ_incorrect Counts all occurences of wrongly predicted branch targets from the BTC [PQ|ROB|LB|ROB_LB|SB|\ ROB_SB|LB_SB|RB_LB_SB|\ DTLB_miss]\ _tag_wait ST_q_tag_wait is listed under sl=20. These counters monitor pipeline behaviour therefore they are not strand specific: PQ_...: cycles Rename stage waits for a Pick Queue tag (might signal memory bound workload for single thread mode, cf. Mail from Richard Smith) ROB_...: cycles Select stage waits for a ROB (ReOrderBuffer) tag LB_...: cycles Select stage waits for a Load Buffer tag SB_...: cycles Select stage waits for Store Buffer tag combinations of the above are allowed, although some of these events can overlap, the counter will only be incremented once per cycle if any of these occur DTLB_...: cycles load or store instructions wait at Pick stage for a DTLB miss tag [ID]TLB_HWTW_\ [L2_hit|L3_hit|L3_miss|all] Counters for HWTW accesses caused by either DTLB or ITLB misses. Canbe further detailed by where they hit IC_miss_L2_L3_hit, IC_miss_local_remote_remL3_hit, IC_miss I$ prefetches that were dropped because they either miss in L2$ or L3$ This variant counts misses regardless if the causing instruction commits or not DC_miss_nospec, DC_miss_[L2_L3|local|remote_L3]\ _hit_nospec D$ misses either in general or detailed by where they hit cf. the explanation for the IC_miss in two flavours for an explanation of _nospec and the reasoning for two DC_miss counters DTLB_miss_asynch counts all DTLB misses asynchronously, there is no way to count them synchronously DC_pref_drop_DC_hit, SW_pref_drop_[DC_hit|buffer_full] L1-D$ h/w prefetches that were dropped because of a D$ hit, counted per core. The others count software prefetches per strand [Full|Partial]_RAW_hit_st_[buf|q] Count events where a load wants to get data that has not yet been stored, i. e. it is still inside the pipeline. The data might be either still in the store buffer or in the store queue. If the load's data matches in the SB and in the store queue the data in buffer takes precedence of course since it is younger [IC|DC]_evict_invalid, [IC|DC|L1]_snoop_invalid, [IC|DC|L1]_invalid_all Counter for invalidated cache evictions per core St_q_tag_wait Number of cycles pipeline waits for a store queue tag, of course counted per core Data_pref_[drop_L2|drop_L3|\ hit_L2|hit_L3|\ hit_local|hit_remote] Data prefetches that can be further detailed by either why they were dropped or where they did hit St_hit_[L2|L3], St_L2_[local|remote]_C2C, St_local, St_remote Store events distinguished by where they hit or where they cause a L2 cache-to-cache transfer, i.e. either a transfer from another L2$ on the same die or from a different die DC_miss, DC_miss_\ [L2_L3|local|remote]_hit D$ misses either in general or detailed by where they hit cf. the explanation for the IC_miss in two flavours for an explanation of _nospec and the reasoning for two DC_miss counters L2_[clean|dirty]_evict Per core clean or dirty L2$ evictions L2_fill_buf_full, L2_wb_buf_full, L2_miss_buf_full Per core L2$ buffer events, all count number of cycles that this state was present L2_pipe_stall Per core cycles pipeline stalled because of L2$ Branches Count branches (Tcc, DONE, RETRY, and SIT are not counted as branches) Br_taken Counts taken branches (Tcc, DONE, RETRY, and SIT are not counted as branches) Br_mispred, Br_dir_mispred, Br_trg_mispred, Br_trg_mispred_\ [far_tbl|indir_tbl|ret_stk] Counter for various branch misprediction events.  Cycles_user counts cycles, attribute setting hpriv, nouser, sys controls addess space to count in Commit-[0|1|2], Commit-0-all, Commit-1-or-2 Number of times either no, one, or two µops commit for a strand. Commit-0-all counts number of times no µop commits for the whole core, cf. footnote 11 to table 10.2 in PRM for a more detailed explanation on how this counters interacts with the privilege levels

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