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• Why lock statements don't scale

  - by Alex.Davies

  We are going to have to stop using lock statements one day. Just like we had to stop using goto statements. The problem is similar, they're pretty easy to follow in small programs, but code with locks isn't composable. That means that small pieces of program that work in isolation can't necessarily be put together and work together. Of course actors scale fine :) Why lock statements don't scale as software gets bigger Deadlocks. You have a program with lots of threads picking up lots of locks. You already know that if two of your threads both try to pick up a lock that the other already has, they will deadlock. Your program will come to a grinding halt, and there will be fire and brimstone. "Easy!" you say, "Just make sure all the threads pick up the locks in the same order." Yes, that works. But you've broken composability. Now, to add a new lock to your code, you have to consider all the other locks already in your code and check that they are taken in the right order. Algorithm buffs will have noticed this approach means it takes quadratic time to write a program. That's bad. Why lock statements don't scale as hardware gets bigger Memory bus contention There's another headache, one that most programmers don't usually need to think about, but is going to bite us in a big way in a few years. Locking needs exclusive use of the entire system's memory bus while taking out the lock. That's not too bad for a single or dual-core system, but already for quad-core systems it's a pretty large overhead. Have a look at this blog about the .NET 4 ThreadPool for some numbers and a weird analogy (see the author's comment). Not too bad yet, but I'm scared my 1000 core machine of the future is going to go slower than my machine today! I don't know the answer to this problem yet. Maybe some kind of per-core work queue system with hierarchical work stealing. Definitely hardware support. But what I do know is that using locks specifically prevents any solution to this. We should be abstracting our code away from the details of locks as soon as possible, so we can swap in whatever solution arrives when it does. NAct uses locks at the moment. But my advice is that you code using actors (which do scale well as software gets bigger). And when there's a better way of implementing actors that'll scale well as hardware gets bigger, only NAct needs to work out how to use it, and your program will go fast on it's own.

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• Security Controls on data for P6 Analytics

  - by Jeffrey McDaniel

  The Star database and P6 Analytics calculates security based on P6 security using OBS, global, project, cost, and resource security considerations. If there is some concern that users are not seeing expected data in P6 Analytics here are some areas to review: 1. Determining if a user has cost security is based on the Project level security privileges - either View Project Costs/Financials or Edit EPS Financials. If expecting to see costs make sure one of these permissions are allocated.  2. User must have OBS access on a Project. Not WBS level. WBS level security is not supported. Make sure user has OBS on project level.  3. Resource Access is determined by what is granted in P6. Verify the resource access granted to this user in P6. Resource security is hierarchical. Project access will override Resource access based on the way security policies are applied. 4. Module access must be given to a P6 user for that user to come over into Star/P6 Analytics. For earlier version of RDB there was a report_user_flag on the Users table. This flag field is no longer used after P6 Reporting Database 2.1. 5. For P6 Reporting Database versions 2.2 and higher, the Extended Schema Security service must be run to calculate all security. Any changes to privileges or security this service must be rerun before any ETL. 6. In P6 Analytics 2.0 or higher, a Weblogic user must exist that matches the P6 username. For example user Tim must exist in P6 and Weblogic users for Tim to be able to log into P6 Analytics and access data based on  P6 security.  In earlier versions the username needed to exist in RPD. 7. Cache in OBI is another area that can sometimes make it seem a user isn't seeing the data they expect. While cache can be beneficial for performance in OBI. If the data is outdated it can retrieve older, stale data. Clearing or turning off cache when rerunning a query can determine if the returned result set was from cache or from the database.

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• CodePlex Daily Summary for Tuesday, July 10, 2012

  CodePlex Daily Summary for Tuesday, July 10, 2012Popular ReleasesjListSelect - jQuery plug-in for a fully customizable select input: 1.0: This is the initial release. Documentation is available using the Documentation tab above and inside the JavaScript code.Push Framework: Push Framework 1.5: This version brings many bug fixes and enhancements to its predecessor.DbDiff: Database Diff and Database Scripting: 1.1.3.3: Sql 2005, Sql 2012 fixes Removed dbdiff recommended default exe because it was a wrong build.re-linq: 1.13.158: This is build 1.13.158 of re-linq. Find the complete release notes for the build here: Release NotesMishra Reader: Mishra Reader beta 3: Per-feed browsing Tons of bug fixes Note: This release requires .NET 4.5 RC. You'll be prompted to install it if you don't already have it. The RC will be upgradeable to the RTM once it's available.MVVM Light Toolkit: MVVM Light Toolkit V4 RTM: The issue with the installer is fixed, sorry for the problems folks This version supports Silverlight 3, Silverlight 4, Silverlight 5, WPF 3.5 SP1, WPF4, Windows Phone 7.0 and 7.5, WinRT (Windows 8). Support for Visual Studio 2010 and Visual Studio 2012 RC.BlackJumboDog: Ver5.6.7: 2012.07.08 Ver5.6.7 (1) ????????????????「?????　Request.Receve()」?????????? (2) Web???????????FlMML customized: FlMML customized ??: FlMML customized ????。 ??、ＰＣＭ??????????、??????。ecBlog: ecBlog 0.2: ecBlog alpha realaseTaskScheduler ASP.NET: Release 3 - 1.2.0.0: Release 3 - Version 1.2.0.0 That version was altered only the library: In TaskScheduler was added new properties: UseBackgroundThreads Enables the use of separate threads for each task. StoreThreadsInPool Manager enables to store in the Pool threads that are performing the tasks. OnStopSchedulerAutoCancelThreads Scheduler allows aborting threads when it is stopped. false if the scheduler is not aborted the threads that are running. AutoDeletedExecutedTasks Allows Manager Delete Task afte...DotNetNuke Persian Packages: ??? ?? ???? ????? ???? 6.2.0: *????? ???? ??? ?? ???? 6.2.0 ? ??????? ???? ????? ???? ??? ????? *????? ????? ????? ??? ??? ???? ??? ??????? ??????? - ???? *?????? ???? ??? ?????? ?? ???? ???? ????? ? ?? ??? ?? ???? ???? ?? *????? ????? ????? ????? ????? / ??????? ???? ?? ???? ??? ??? - ???? *???? ???? ???? ????? ? ??????? ??? ??? ??? ?? ???? *????? ????? ???????? ??? ? ??????? ?? ?? ?????? ????? ????????? ????? ?????? - ???? *????? ????? ?????? ????? ?? ???? ?? ?? ?? ???????? ????? ????? ????????? ????? ?????? *???? ?...Cypher Bot: Cypher Bot 4.1: Cypher Bot is the most advanced encryption tool on the planet.... and now it actually works. That's right we fixed the bugs! For a full program summary go to the Home Page or visit www.iRareMedia.com So what's new? We've pretty much fixed all the bugs, but here's a run down if you wanna know exactly what's different: Fixed Installation / Setup Error, where an error message would display: "No Internet Connection, Try Again Later" Fixed File Encryption / Decryption error where the file exten...Coding4Fun Kinect Service: Coding4Fun Kinect Service v1.5: Requires Kinect for Windows SDK v1.5 Minor bug fixes + Kinect for Windows SDK v1.5 Aligning version with the Kinect for Windows SDK requiredtedplay: tedplay 1.1: tedplay 1.1 source and Win32 binary is out now. Changes are: SID card support Commodore 64 PSID music format support optimized FIR filter global hotkeys for skipping tracks (Windows only) module properties window (Windows only) mutable noise channel via GUI button (Windows only) disable SID card from the menu (Windows only) bugfixes PSID tunes are played on the C64 clock frequency but in a Commodore plus/4 virtual machine. The purpose is not to have yet another SID player, but t...xUnit.net Contrib: xunitcontrib-resharper 0.6 (RS 7.0, 6.1.1): xunitcontrib release 0.6 (ReSharper runner) This release provides a test runner plugin for Resharper 7.0 (EAP build 82) and 6.1, targetting all versions of xUnit.net. (See the xUnit.net project to download xUnit.net itself.) Copies of the plugin that support previous verions of ReSharper can be downloaded from this release. The plan is to support the latest revisions of the last two paid-for major versions of ReSharper (namely 7.0 and 6.1) Also note that all builds work against ALL VERSIONS...Umbraco CMS: Umbraco 4.8.0 Beta: Whats newuComponents in the core Multi-Node Tree Picker, Multiple Textstring, Slider and XPath Lists Easier Lucene searching built in IFile providers for easier file handling Updated 3rd party libraries Applications / Trees moved out of the database SQL Azure support added Various bug fixes Getting Started A great place to start is with our Getting Started Guide: Getting Started Guide: http://umbraco.codeplex.com/Project/Download/FileDownload.aspx?DownloadId=197051 Make sure to...CODE Framework: 4.0.20704.0: See CODE Framework (.NET) Change Log for changes in this version.xUnit.net - Unit testing framework for C# and .NET (a successor to NUnit): xUnit.net 1.9.1: xUnit.net release 1.9.1Build #1600 Important note for Resharper users: Resharper support has been moved to the xUnit.net Contrib project. Important note for TestDriven.net users: If you are having issues running xUnit.net tests in TestDriven.net, especially on 64-bit Windows, we strongly recommend you upgrade to TD.NET version 3.0 or later. Important note for VS2012 users: The VS2012 runner is in the Visual Studio Gallery now, and should be installed via Tools | Extension Manager from insi...MVC Controls Toolkit: Mvc Controls Toolkit 2.2.0: Added Modified all Mv4 related features to conform with the Mvc4 RC Now all items controls accept any IEnumerable<T>(before just List<T> were accepted by most of controls) retrievalManager class that retrieves automatically data from a data source whenever it catchs events triggered by filtering, sorting, and paging controls move method to the updatesManager to move one child objects from a father to another. The move operation can be undone like the insert, update and delete operatio...IronPython: 2.7.3: On behalf of the IronPython team, I'm happy to announce the final release of IronPython 2.7.3. This release includes everything from IronPython 54498, 62475, and 74478 as well. Like all IronPython 2.7-series releases, .NET 4 is required to install it. Installing this release will replace any existing IronPython 2.7-series installation. The incompatibility with IronRuby has been resolved, and they can once again be installed side-by-side. The biggest improvements in IronPython 2.7.3 are: the...New ProjectsAuction Helper: Auction HelperBizTalk 0MQ Adapter: The BizTalk 0MQ Adapter allows BizTalk to send and receive messages using the ZeroMq cross platform messaging framework.fluentstatement: FluentStatement is a library for .NET usable to create Expressions Trees through its fluent interface. These ET can contain Lambda Expressions and Statements.Freemansoft: ??????????????????gppsoftware: gppsoftwarejAutoFitText - jQuery plug-in to auto-fit text similar to iOS applications: This is a jQuery plug-in that automatically fits text in a specific container using font size manipulation and/or string truncation. The end result is simjDelayedAction - jQuery plug-in to allow a delayed reaction to an event: This is a jQuery plug-in that allows the creation of an event (or multiple event) handler with a delay that can be extended or canceled before reacting.jInMemoryImageLoader - jQuery plug-in to asynchronously load an image: This is a jQuery plug-in that allows the asynchronous, in-memory loading of an image file with a callback for when it has succeeded or failed to load.jListSelect - jQuery plug-in for a fully customizable select input: A jQuery plug-in that allows you to create a fully customizable select input.jNumericalInput - jQuery plug-in to limit a text input to only numeric values: A simple jQuery plug-in that, when applied to an input of type text, only allows the input to have a numeric value (positive or negative).jVerticalAlignMiddle - jQuery plug-in to vertically align elements: A simple jQuery plug-in that vertically centers one element within its parent container.lhhp.net: this project is for testLiteCode: Your having enough of crackers, reverse engineers ? With LiteCode you can host your code remotely at a server where no cracker can touch itNetEx .net tool set: NetEx .net tool setOpenFlashChart: OpenFlashChart ??????Flash Chart??。 Project RPG: Developers learn how to design a game from the ground up.saka-pon.net: saka-pon.net.School System: Its all about school managementSeeForYourself: SeeForYourSelfSharepoint JQuery Editor Web Part: Enables quick JQuery development by executing your code immediately while in desing mode.Simplex: Simplex ???????????????J2EE???????????????。 Stuff.NET: This library provides several useful classes and methods to deal with frequently appearing challenges. e.g.: pathfinding, forms/controls, dynamic compiling, ...

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• PeopleSoft New Design Solves Navigation Problem

  - by Applications User Experience

  Anna Budovsky, User Experience Principal Designer, Applications User Experience In PeopleSoft we strive to improve User Experience on all levels. Simplifying navigation and streamlining access to the most important pages is always an important goal. No one likes to waste time waiting for pages to load and watching a spinning glass going on and on. Those performance-affecting server trips, page-load waits and just-too-many clicks were complained about for a long time. Something had to be done. A few new designs came in PeopleSoft 9.2 helping users to access their everyday work areas easier and faster. For example, Dashboard and Work Center aggregate most accessed information sections on a single page; Related Information allows users to complete transaction-related-research without interrupting a transaction and Secure Search gets users to a specific page directly. Today we’ll talk about the Actions menu. Most PeopleSoft pages are shared between individual products and product lines. It means changing the content on a single page involves Oracle development and quality assurance time for making and testing the changes. In order to streamline the navigation and cut down on accessing PeopleSoft pages one-page-at-a-time, we introduced a new menu design. The new menu allows accessing shared pages without the Oracle development team making any local changes, and it works as an additional one-click-path to specific high-traffic actionable pages. Let’s look at how many steps it took to Change Salary for an employee in HCM 9.1 before: Figure 1. BEFORE: The 6 steps a user would take to Change Salary in PeopleSoft HCM 9.1 In PeopleSoft 9.1 it took 5 steps + page loading time + additional verification time for making sure a correct employee is selected from the table. In PeopleSoft 9.2 it only takes 2 steps. To complete Ad Hoc Change Salary action, the user can start from the HCM Manager's Dashboard, click the Action menu within a table, choose a menu option, and access a correct employee’s details page to take an action. Figure 2. AFTER: The 2 steps a user would take to Change Salary in PeopleSoft HCM 9.2 The new menu is placed on a row level which ensures the user accesses the correct employee’s details page. The Actions menu separates menu options into hierarchical sections which help to scan and access the correct option quickly. The new menu’s small size and its structure enabled users to access high-traffic pages from any page and from any part of the page. No more spinning hourglass, no more multiple pages upload. The flexible design fits anywhere on a page and provides a fast and reliable path to the correct destination within the product. Now users can: Access any target page no matter how far it is buried from the starting point; Reduce navigation and page-load time; Improve productivity and reduce errors. The new menu design is available and widely used in all PeopleSoft 9.2 product lines.

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• SharePoint 2010 HierarchicalConfig Caching Problem

  - by Damon

  We've started using the Application Foundations for SharePoint 2010 in some of our projects at work, and I came across a nasty issue with the hierarchical configuration settings.  I have some settings that I am storing at the Farm level, and as I was testing my code it seemed like the settings were not being saved - at least that is what it appeared was the case at first.  However, I happened to reset IIS and the settings suddenly appeared.  Immediately, I figured that it must be a caching issue and dug into the code base.  I found that there was a 10 second caching mechanism in the SPFarmPropertyBag and the SPWebAppPropertyBag classes.  So I ran another test where I waited 10 seconds to make sure that enough time had passed to force the caching mechanism to reset the data.  After 10 minutes the cache had still not cleared.  After digging a bit further, I found a double lock check that looked a bit off in the GetSettingsStore() method of the SPFarmPropertyBag class: if (_settingStore == null || (DateTime.Now.Subtract(lastLoad).TotalSeconds) > cacheInterval)) { //Need to exist so don't deadlock. rrLock.EnterWriteLock(); try { //make sure first another thread didn't already load... if (_settingStore == null) { _settingStore = WebAppSettingStore.Load(this.webApplication); lastLoad = DateTime.Now; } } finally { rrLock.ExitWriteLock(); } } What ends up happening here is the outer check determines if the _settingStore is null or the cache has expired, but the inner check is just checking if the _settingStore is null (which is never the case after the first time it's been loaded).  Ergo, the cached settings are never reset.  The fix is really easy, just add the cache checking back into the inner if statement. //make sure first another thread didn't already load... if (_settingStore == null || (DateTime.Now.Subtract(lastLoad).TotalSeconds) > cacheInterval) { _settingStore = WebAppSettingStore.Load(this.webApplication); lastLoad = DateTime.Now; } And then it starts working just fine. as long as you wait at least 10 seconds for the cache to clear.

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• Fail to launch application (CreateProcess error=87), can't use shorten classpath workaround

  - by Ivo Bosticky

  When I launch our application in Eclipse on Windows I receive the following error: Exception occured executing command line. Cannot run program .. : CreateProcess error=87, The parameter is incorrect I've solved this in the past by shortening the CLASSPATH. I've now come to a point where I can no longer shorten the CLASSPATH, and would like to know if there are any other workarounds. http://support.microsoft.com/kb/830473 seems to indicate that the max command prompt line length in windows xp is 8191 characters, and the only solution is to shorten folder names, reduce depth of folder trees, using parameter files, etc.

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• How to determine if binary tree is balanced?

  - by user69514

  It's been a while from those school years. Got a job as IT specialist at a hospital. Trying to move to do some actual programming now. I'm working on binary trees now, and I was wondering what would be the best way to determine if the tree is height-balanced. I was thinking of something along this: public boolean isBalanced(Node root){ if(root==null){ return true; //tree is empty } else{ int lh = root.left.height(); int rh = root.right.height(); if(lh - rh > 1 || rh - lh > 1){ return false; } } return true; } Is this a good implementation? or am I missing something?

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• Please explain some of Paul Graham's points on LISP

  - by kunjaan

  I need some help understanding some of the points from Paul Graham's article http://www.paulgraham.com/diff.html A new concept of variables. In Lisp, all variables are effectively pointers. Values are what have types, not variables, and assigning or binding variables means copying pointers, not what they point to. A symbol type. Symbols differ from strings in that you can test equality by comparing a pointer. A notation for code using trees of symbols. The whole language always available. There is no real distinction between read-time, compile-time, and runtime. You can compile or run code while reading, read or run code while compiling, and read or compile code at runtime. What do these points mean How are they different in languages like C or Java? Do any other languages other than LISP family languages have any of these constructs now?

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• How do I aggregate results from an Adjacency list using PHP's SPL

  - by Stephen J. Fuhry

  I've tried using nested sets, and they become very difficult to maintain when dealing with multiple trees and lots of other complications.. I'd like to give PHP's SPL library a stab at this (btw, we are PHP 5.3, MySQL 5.1). Given two datasets: The Groups: +-------+--------+---------------------+---------------+ | id | parent | Category Name | child_key | +-------+--------+---------------------+---------------+ | 11133 | 7707 | Really Cool Products| 47054 | | 7709 | 7708 | 24" Monitors | 57910 | | 7713 | 7710 | Hot Tubs | 35585 | | 7716 | 7710 | Hot Dogs | 00395 | | 11133 | 7707 | Really Cool Products| 66647 | | 7715 | 7710 | Suction Cups | 08396 | +-------+--------+---------------------+---------------+ The Items +------------+------------+-----------+----------+---------+ | child_key | totalprice | totalcost | totalqty | onorder | (jan, feb, mar..) +------------+------------+-----------+----------+---------+ | 24171 | 10.50 | 20.10 | 200 | 100 | | 35685 | 10.50 | 20.10 | 200 | 100 | | 76505 | 10.50 | 20.10 | 200 | 100 | | 04365 | 10.50 | 20.10 | 200 | 100 | | 01975 | 10.50 | 20.10 | 200 | 100 | | 12150 | 10.50 | 20.10 | 200 | 100 | | 40060 | 10.50 | 20.10 | 200 | 100 | | 08396 | 10.50 | 20.10 | 200 | 100 | +------------+------------+-----------+----------+---------+ The figures are actually much more complicated than this (I am actually aggregating a variable amount of months or years over the past 15yrs, so there may need to be 20 columns of aggregated results). I have been trying to figure out RecursiveIterator and IteratorAggregate, but I am having a difficult time finding real world examples that are generic enough to really wrap my head around these classes. Can someone give me a head start?

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• Graph theory in python

  - by Dan

  I was wondering how people deal with graph theory in python? How is a graph stored? Are there libraries for this? For example how would I input a graph and then find its Chromatic polynomial? Or its girth? Or the number of unique spanning trees? How about problems that involve edge weight like salesman problems? I don't need all of these answered, I'm just looking for a method or tool set that will be able to help me approach solve problems like this. Thanks, Dan

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• Good projects to learn OCaml and F#

  - by Yin Zhu

  After learning the basic syntax, reading some non-trivial code is a fast way to learn a language. We can also learn how to design a library/software during reading others' code. I have following lists. A Chess program in OCaml by Tomek Czajka. Hal Daumé has written several machine learning libraries in Ocaml. Including decision trees, logistic regression and SVM. All of them are near-production-quality code. A Chess Game Analysis program in F# in Microsoft Research. The above three are my favorites. Will you suggest some other sources? General purpose open source software are good, specialized open source like the three I list here are even more welcome.

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• Is recursion ever faster than looping?

  - by Carson Myers

  I know that recursion is sometimes a lot cleaner than looping, and I'm not asking anything about when I should use recursion over iteration, I know there are lots of questions about that already. What I'm asking is, is recursion ever faster than a loop? To me it seems like, you would always be able to refine a loop and get it to perform more quickly than a recursive function because the loop is absent constantly setting up new stack frames. I'm specifically looking for whether recursion is faster in applications where recursion is the right way to handle the data, such as in some sorting functions, in binary trees, etc.

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• Are there any B-tree programs or sites that show visually how a B-tree works

  - by Phenom

  I found this website that lets you insert and delete items from a B-tree and shows you visually what the B-tree looks like: java b-tree I'm looking for another website or program similar to this. This site does not allow you to specify a B-tree of order 4 (4 pointers and 3 elements), it only lets you specify B-trees with an even number of elements. Also, if possible, I'd like to be able to insert letters instead of numbers. I think I actually found a different site but that was a while ago and can't find it anymore.

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• Dependency Injection book recommendation(s)

  - by Portman

  It seems like there are very few books (yes, I read books) on Dependency Injection. The Amazon tag for "dependency injection" lists only a few titles, and all of them are specifically about Spring for Java. Are there any books out there that cover DI/IoC in general? Or any that include a survey of multiple DI frameworks? Or any that cover .NET in lieu of or in addition to Java? Or do we have to rely on this newfangled interweb instead of dead trees...

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• Bash Script - Traffic Shaping

  - by Craig-Aaron

  hey all, I was wondering if you could have a look at my script and help me add a few things to it, How do I get it to find how many active ethernet ports I have? and how do I filter more than 1 ethernet port How I get this to do a range of IP address? Once I have a few ethenet ports I need to add traffic control to each one #!/bin/bash # Name of the traffic control command. TC=/sbin/tc # The network interface we're planning on limiting bandwidth. IF=eth0 # Network card interface # Download limit (in mega bits) DNLD=10mbit # DOWNLOAD Limit # Upload limit (in mega bits) UPLD=1mbit # UPLOAD Limit # IP address range of the machine we are controlling IP=192.168.0.1 # Host IP # Filter options for limiting the intended interface. U32="$TC filter add dev $IF protocol ip parent 1:0 prio 1 u32" start() { # Hierarchical Token Bucket (HTB) to shape bandwidth $TC qdisc add dev $IF root handle 1: htb default 30 #Creates the root schedlar $TC class add dev $IF parent 1: classid 1:1 htb rate $DNLD #Creates a child schedlar to shape download $TC class add dev $IF parent 1: classid 1:2 htb rate $UPLD #Creates a child schedlar to shape upload $U32 match ip dst $IP/24 flowid 1:1 #Filter to match the interface, limit download speed $U32 match ip src $IP/24 flowid 1:2 #Filter to match the interface, limit upload speed } stop() { # Stop the bandwidth shaping. $TC qdisc del dev $IF root } restart() { # Self-explanatory. stop sleep 1 start } show() { # Display status of traffic control status. $TC -s qdisc ls dev $IF } case "$1" in start) echo -n "Starting bandwidth shaping: " start echo "done" ;; stop) echo -n "Stopping bandwidth shaping: " stop echo "done" ;; restart) echo -n "Restarting bandwidth shaping: " restart echo "done" ;; show) echo "Bandwidth shaping status for $IF:" show echo "" ;; *) pwd=$(pwd) echo "Usage: tc.bash {start|stop|restart|show}" ;; esac exit 0 thanks

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• Lucene's nested query evaluation regarding negation

  - by ponzao

  Hi, I am adding Apache Lucene support to Querydsl (which offers type-safe queries for Java) and I am having problems understanding how Lucene evaluates queries especially regarding negation in nested queries. For instance the following two queries in my opinion are semantically the same, but only the first one returns results. +year:1990 -title:"Jurassic Park" +year:1990 +(-title:"Jurassic Park") The simplified object tree in the second example is shown below. query : Query clauses : ArrayList [0] : BooleanClause "MUST" occur : BooleanClause.Occur "year:1990" query : TermQuery [1] : BooleanClause "MUST" occur : BooleanClause.Occur query : BooleanQuery clauses : ArrayList [0] : BooleanClause "MUST_NOT" occur : BooleanClause.Occur "title:"Jurassic Park"" query : TermQuery Lucene's own QueryParser seems to evaluate "AND (NOT" into the same kind of object trees. Is this a bug in Lucene or have I misunderstood Lucene's query evaluation? I am happy to give more information if necessary.

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• (interactive) graph as in graph theory on a web page ?

  - by LB

  Hi, I have to integrate a graph with nodes and edges on a web page. Ideally, i would like to be able to interact with it (like moving the nodes around). Actually, i'm beginning by representing trees, so i would appreciate to be able to collapse subtrees. How can I do that ? I was considering google-visualization api but i wasn't able to find the kind of visualization i'm looking for (org chart doesn't allow to have multiple fathers, if i understood well) I've got no idea of the kind of technology so my tagging may not be really accurate :-). thanks

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• Spatial index for geo coordinates?

  - by Michael Borgwardt

  What kind of data structure could be used for an efficient nearest neighbor search in a large set of geo coordinates? With "regular" spatial index structures like R-Trees that assume planar coordinates, I see two problems (Are there others I have overlooked?): Wraparound at the poles and the International Date Line Distortion of distances near the poles How can these factors be allowed for? I guess the second one could compensated by transforming the coordinates. Can an R-Tree be modified to take wraparound into account? Or are there specialized geo-spatial index structures?

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• WPF with MVVM and Prismv2 - Event Bubbling?

  - by depictureboy

  What is the best way to get an event from a child or grandchild module up to the parent Shell? For instance, if I have a view in a module that is actually 2 levels away from the Shell, and I have a Window behavior. Is the eventaggregator really the best way to do this? it seems like overkill. I just want my MainShell to watch for a change in the IsDialogOpen Property on the ViewModels in all my child modules. I feel like I am missing the trees for the forest...

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• Generic Data Structure Description Language

  - by Jon Purdy

  I am wondering whether there exists any declarative language for arbitrarily describing the format and semantics of a data structure, that can be compiled to a specific implementation of that structure in any of a set of target languages. That is, something like a generic data definition language but geared toward describing arbitrary data structures such as vectors, lists, trees, etc., and the semantics of operations on those structures. I ask because I had an idea for a feasible implementation of this concept, and I'm just wondering whether it's worth it, and, consequently, whether it's been done before. Another, slightly more abstract question: is there any real difference between the normative specification of a data structure (what it does) and its implementation (how it does it)?

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• Creating mdraid device on top of other existing mdraid devices

  - by Dmitriusan

  I'm considering creating something like "hierarchical raid" and wondering whether it is possible using pure mdraid. Moreover, I'm going to boot from this device. I'm using Ubuntu Server 12.04 LTS with Grub2 bootloader. Motivation behind doing that is: I have 4 x 1tb 7200rpm disks. Two are newer and faster (up to 200mb/sec) and other two are slower (up to 140mb/sec). I want to create RAID-0 device from them. When creating such RAID-0 directly from 4 hard disks, I get summary speed up to ~480mb/sec. That is roughly 4*120mb/sec, so RAID-0 works with speed of the slowest device. I have an idea to create a separate RAID-0 md0 device from 500gb partitions of slower hard disks. Theoretically, this md0 device will have speed 2*140=240~280mb/sec. After that, I'm going to add this md0 device to RAID-0 with faster disks, finishing with up to 3*200=600mb/sec. Stripe-width for this raid will be 2x times bigger than for underlying raid with slow disks. Questions are: is it possible or I'm missing something? will that work as expected? can I boot from such consolidated raid device? any better ideas? any pitfalls? I don't want to use fakeraid for consolidating slow disks for multiple reasons (portability, ability to customize parameters and so on). PS Speed is needed for home virtualization server and just for experience/fun. Reliability is provided via regular automatic backups to a separate device. PPS I considered also using different stripe-width for hard disks with different speed in single raid, but mdraid does not seem to support that.

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• MVVM View-First Approach How Change View

  - by CodeWeasel

  Hi everybody, Does anybody have an idea how to change screens (views) in a MVVM View-First-Approach (The view instantiates the ViewModel: DataContext="{Binding Source={StaticResource VMLocator}, Path=Find[EntranceViewModel]}" ) For example: In my MainWindow (Shell) I show a entrance view with a Button "GoToBeach". <Window> <DockPanel> <TextBox DockPanel.Dock="Top" Text="{Binding Title}" /> <view.EntranceView DockPanel.Dock="Top" /> </DockPanel> </Window> When the button is clicked I want to get rid of the "EntranceView" and show the "BeachView". I am really curious if somebody knows a way to keep the View-First Approach and change the screen (view) to the "BeachView". I know there are several ways to implement it in a ViewModel-First Approach, but that is not the question. Perhabs I missed something in my mvvm investigation and can't see the wood for the trees... otherwise i am hoping for a inspiring discussion.

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• Any competitors to db4o on compact framework?

  - by MrJeepster

  We've been trying db4o for persisting objects on the compact framework. It works very well from our tests so far. However, it appears they are on the expensive side for small startups with minimal units needed. Does anyone know of any similar object databases for the compact framework? How about a open source one that is free for commercial use? :) Thank you. EDIT: We're really looking for an object database. We don't want to create our own persistence framework at this point and would prefer being able to just save/retrieve the actual object trees.

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• Null Reference Exception on MVVM pattern

  - by Mohit Deshpande

  System.NullReferenceException Object reference not set to an instance of an object. at Microsoft.Windows.Design.DocumentModel.Trees.MarkupDocumentTreeManager.<FindMarkupNodePath>d__0.MoveNext() at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable1 source) at MS.Internal.Services.DocumentInformationServiceImpl.get_Root() at MS.Internal.Designer.VSDesigner.Load() at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedView.Load() at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedDesignerFactory.Load(IsolatedView view) at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view) at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view) at MS.Internal.Host.Isolation.IsolatedDesigner.Load() at MS.Internal.Designer.DesignerPane.LoadDesignerView() I keep getting this exception and then intellisense stops working in a XAML text editor. Any ideas why?

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• Are some data structures more suitable for functional programming than others?

  - by Rob Lachlan

  In Real World Haskell, there is a section titled "Life without arrays or hash tables" where the authors suggest that list and trees are preferred in functional programming, whereas an array or a hash table might be used instead in an imperative program. This makes sense, since it's much easier to reuse part of an (immutable) list or tree when creating a new one than to do so with an array. So my questions are: Are there really significantly different usage patterns for data structures between functional and imperative programming? If so, is this a problem? What if you really do need a hash table for some application? Do you simply swallow the extra expense incurred for modifications?

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