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  • Jump handling and gravity

    - by sprawl
    I'm new to game development and am looking for some help on improving my jump handling for a simple side scrolling game I've made. I would like to make the jump last longer if the key is held down for the full length of the jump, otherwise if the key is tapped, make the jump not as long. Currently, how I'm handling the jumping is the following: Player.prototype.jump = function () { // Player pressed jump key if (this.isJumping === true) { // Set sprite to jump state this.settings.slice = 250; if (this.isFalling === true) { // Player let go of jump key, increase rate of fall this.settings.y -= this.velocity; this.velocity -= this.settings.gravity * 2; } else { // Player is holding down jump key this.settings.y -= this.velocity; this.velocity -= this.settings.gravity; } } if (this.settings.y >= 240) { // Player is on the ground this.isJumping = false; this.isFalling = false; this.velocity = this.settings.maxVelocity; this.settings.y = 240; } } I'm setting isJumping on keydown and isFalling on keyup. While it works okay for simple use, I'm looking for a better way handle jumping and gravity. It's a bit buggy if the gravity is increased (which is why I had to put the last y setting in the last if condition in there) on keyup, so I'd like to know a better way to do it. Where are some resources I could look at that would help me better understand how to handle jumping and gravity? What's a better approach to handling this? Like I said, I'm new to game development so I could be doing it completely wrong. Any help would be appreciated.

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  • To SYNC or not to SYNC – Part 4

    - by AshishRay
    This is Part 4 of a multi-part blog article where we are discussing various aspects of setting up Data Guard synchronous redo transport (SYNC). In Part 1 of this article, I debunked the myth that Data Guard SYNC is similar to a two-phase commit operation. In Part 2, I discussed the various ways that network latency may or may not impact a Data Guard SYNC configuration. In Part 3, I talked in details regarding why Data Guard SYNC is a good thing, and the distance implications you have to keep in mind. In this final article of the series, I will talk about how you can nicely complement Data Guard SYNC with the ability to failover in seconds. Wait - Did I Say “Seconds”? Did I just say that some customers do Data Guard failover in seconds? Yes, Virginia, there is a Santa Claus. Data Guard has an automatic failover capability, aptly called Fast-Start Failover. Initially available with Oracle Database 10g Release 2 for Data Guard SYNC transport mode (and enhanced in Oracle Database 11g to support Data Guard ASYNC transport mode), this capability, managed by Data Guard Broker, lets your Data Guard configuration automatically failover to a designated standby database. Yes, this means no human intervention is required to do the failover. This process is controlled by a low footprint Data Guard Broker client called Observer, which makes sure that the primary database and the designated standby database are behaving like good kids. If something bad were to happen to the primary database, the Observer, after a configurable threshold period, tells that standby, “Your time has come, you are the chosen one!” The standby dutifully follows the Observer directives by assuming the role of the new primary database. The DBA or the Sys Admin doesn’t need to be involved. And - in case you are following this discussion very closely, and are wondering … “Hmmm … what if the old primary is not really dead, but just network isolated from the Observer or the standby - won’t this lead to a split-brain situation?” The answer is No - It Doesn’t. With respect to why-it-doesn’t, I am sure there are some smart DBAs in the audience who can explain the technical reasons. Otherwise - that will be the material for a future blog post. So - this combination of SYNC and Fast-Start Failover is the nirvana of lights-out, integrated HA and DR, as practiced by some of our advanced customers. They have observed failover times (with no data loss) ranging from single-digit seconds to tens of seconds. With this, they support operations in industry verticals such as manufacturing, retail, telecom, Internet, etc. that have the most demanding availability requirements. One of our leading customers with massive cloud deployment initiatives tells us that they know about server failures only after Data Guard has automatically completed the failover process and the app is back up and running! Needless to mention, Data Guard Broker has the integration hooks for interfaces such as JDBC and OCI, or even for custom apps, to ensure the application gets automatically rerouted to the new primary database after the database level failover completes. Net Net? To sum up this multi-part blog article, Data Guard with SYNC redo transport mode, plus Fast-Start Failover, gives you the ideal triple-combo - that is, it gives you the assurance that for critical outages, you can failover your Oracle databases: very fast without human intervention, and without losing any data. In short, it takes the element of risk out of critical IT operations. It does require you to be more careful with your network and systems planning, but as far as HA is concerned, the benefits outweigh the investment costs. So, this is what we in the MAA Development Team believe in. What do you think? How has your deployment experience been? We look forward to hearing from you!

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  • MapReduce

    - by kaleidoscope
    MapReduce is a programming model and an associated implementation for processing and generating large data sets. Users specify a map function that processes a key/value pair to generate a set of  intermediate key/value pairs, and a reduce function that merges all intermediate values associated with the same intermediate key. Many real world tasks are expressible in this model, as shown in the paper. Programs written in this functional style are automatically parallelized and executed on a large cluster of commodity machines. The run-time system takes care of the details of partitioning the input data,  scheduling the program's execution across a set of machines, handling machine failures, and managing the required inter-machine communication. This allows programmers without any experience with parallel and distributed systems to easily utilize the resources of a large distributed system. Example: A process to count the appearances of each different word in a set of documents void map(String name, String document):   // name: document name   // document: document contents   for each word w in document:     EmitIntermediate(w, 1); void reduce(String word, Iterator partialCounts):   // word: a word   // partialCounts: a list of aggregated partial counts   int result = 0;   for each pc in partialCounts:     result += ParseInt(pc);   Emit(result); Here, each document is split in words, and each word is counted initially with a "1" value by the Map function, using the word as the result key. The framework puts together all the pairs with the same key and feeds them to the same call to Reduce, thus this function just needs to sum all of its input values to find the total appearances of that word.   Sarang, K

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  • Bunny Inc. Season 2: Spice Up Your Applications

    - by kellsey.ruppel
    The quality and effectiveness of online services is strongly dependent on core business processes and applications. Nonetheless, user friendly composite applications are still a challenge for enterprises, especially if they are also requested to embed social technologies to empower customization and facilitate collaboration. You can operate like Hare Inc. and disappoint your customers, delivering inefficient services and wasting outside-in innovation opportunities, or you can operate like Bunny Inc., leveraging participatory services to improve connections between people, information and applications. And maybe you are ahead enough to adopt a public enterprise cloud to drive business through organic conversations and jump-start productivity with more-purposeful social networking and contextual enterprise collaboration. Don't miss this second episode of Social Bunnies Season 2 to learn how to increase the value of existing enterprise systems while augmenting employee productivity, business flexibility and organizational awareness. Still looking for more information on composite applications. We've got a ton of great resources for you to learn more!

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  • Creating a chain of certificates

    - by StackedCrooked
    This question is a follow up to my previous question, which was, in retrospect, not completely answered: http://superuser.com/questions/126121/how-to-create-my-own-certificate-chain. I'll represent my certificate chain like this: ROOT - A - B - C - ... I am now able to create the ROOT and A certificates, but I didn't succeed in continueing the chain. My command for creating the root certificate is: openssl req -new -newkey rsa:1024 -nodes -out ca.csr -keyout ca.key openssl x509 -trustout -signkey ca.key -days 365 -req -in ca.csr -out ca.pem Certificate A: openssl genrsa -out client.key 1024 openssl req -new -key client.key -out client.csr openssl ca -in client.csr -out client.cer This command depends on the root certificate implicitly using the data found in the openssl config file. Certificate B will only rely on A, so the previous command won't work here. How can I complete the chain?

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  • Demantra Partitioning and the First PK Column

    - by user702295
      We have found that it is necessary in Demantra to have an index that matches the partition key, although it does not have to be the PK.  It is ok   to create a new index instead of changing the PK.   For example, if my PK on SALES_DATA is (ITEM_ID, LOCATION_ID, SALES_DATE) and I decide partition by SALES_DATE, then I should add an index starting   with the partition key like this: (SALES_DATE, ITEM_ID, LOCATION_ID).   * Note that the first column of the new index matches the partition key.   It might also be helpful to create a 2nd index with the other PK columns reversed (SALES_DATE, LOCATION_ID, ITEM_ID). Again, the first column   matches the partition key.

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  • XF86 keybinds in Openbox

    - by vasa1
    Lubuntu uses Openbox as its window manager. ~/.config/openbox/lubuntu-rc.xml is a file that specifies, among other things, keybinds for various commands. Most of the keybinds in lubuntu-rc.xml use modifier keys such as Control, Shift, Alt, and Super. For example, one way of opening a terminal window would be by pressing Control+Alt+T together: <!-- Launch a terminal on Ctrl + Alt + T--> <keybind key="C-A-T"> <action name="Execute"> <command>lxsession-default terminal</command> </action> </keybind> But there is also this: <!-- Keybinding for terminal button--> <keybind key="XF86WWW"> <action name="Execute"> <command>lxsession-default terminal</command> </action> </keybind> <keybind key="XF86Terminal"> <action name="Execute"> <command>lxsession-default terminal</command> </action> </keybind> What are keybind key="XF86WWW" and keybind key="XF86Terminal"? How do I locate these keys on my laptop's keyboard? My laptop is a Dell Inspiron N 1545 from 2008.

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  • How do I get this Mac OS X exposé behavior?

    - by quangtruong1985
    In Mac os x, I can move all windows to the nearest corner by hitting F11 key. I'm just wondering if there is a compiz plugin works like that. I know that there is Scale plugin already. But all that I want is something like this. You'll see, press a key and all windows fly off to nearest corner so I can drag/drop file or do something else on my desktop, then press the key again and all windows fly back.

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  • CodePlex Daily Summary for Friday, May 30, 2014

    CodePlex Daily Summary for Friday, May 30, 2014Popular ReleasesSEToolbox: 01.032.014 Release 2: Fixed flaw in startup if second Toolbox was started. Added thumbnail zooming in load dialog. Added mirror for new ConveyorTubeCurvedMedium. Added dedicated server support :- Repair will not add missing player to dedicated server. Distances measured to origin (0,0,0) when no player exists. Dedicated Service Server game denied write access unless SEToolbox is run as Admin. Additional information in Load dialog. Installation of this version will replace older version.Vi-AIO SearchBar: Vi – AIO Search Bar: Version 1.0Composite Iconote: Composite Iconote: This is a composite has been made by Microsoft Visual Studio 2013. Requirement: To develop this composite or use this component in your application, your computer must have .NET framework 4.5 or newer.HigLabo: HigLabo_20140529: Fixed HttpClient ContentLength bug.Magick.NET: Magick.NET 6.8.9.101: Magick.NET linked with ImageMagick 6.8.9.1. Breaking changes: - Int/short Set methods of WritablePixelCollection are now unsigned. - The Q16 build no longer uses HDRI, switch to the new Q16-HDRI build if you need HDRI.StudioShell: StudioShell 1.6.6: placeholder release for WIX issue work artifactsMath.NET Numerics: Math.NET Numerics v3.0.0-beta02: Full History Linear Algebra: optimized sparse-sparse and sparse-diagonal matrix products. ~Christian Woltering transpose at storage level, optimized sparse transpose. ~Christian Woltering optimized inplace-map, indexed submatrix-map. optimized clearing a set of rows or columns. matrix FoldRows/FoldColumns. matrix column/row norms, normalization. prefer enums over boolean parameters (e.g. `Zeros.AllowSkip`). IsSymmetric is now a method, add IsConjugateSymmetric. breaking Eigen...QuickMon: Version 3.13: 1. Adding an Audio/sound notifier that can be used to simply draw attention to the application of a warning pr error state is returned by a collector. 2. Adding a property for Notifiers so it can be set to 'Attended', 'Unattended' or 'Both' modes. 3. Adding a WCF method to remote agent host so the version can be checked remotely. 4. Adding some 'Sample' monitor packs to installer. Note: this release and the next release (3.14 aka Pie release) will have some breaking changes and will be incom...fnr.exe - Find And Replace Tool: 1.7: Bug fixes Refactored logic for encoding text values to command line to handle common edge cases where find/replace operation works in GUI but not in command line Fix for bug where selection in Encoding drop down was different when generating command line in some cases. It was reported in: https://findandreplace.codeplex.com/workitem/34 Fix for "Backslash inserted before dot in replacement text" reported here: https://findandreplace.codeplex.com/discussions/541024 Fix for finding replacing...VG-Ripper & PG-Ripper: VG-Ripper 2.9.59: changes NEW: Added Support for 'GokoImage.com' links NEW: Added Support for 'ViperII.com' links NEW: Added Support for 'PixxxView.com' links NEW: Added Support for 'ImgRex.com' links NEW: Added Support for 'PixLiv.com' links NEW: Added Support for 'imgsee.me' links NEW: Added Support for 'ImgS.it' linksXsemmel - XML Editor and Viewer: 29-MAY-2014: WINDOWS XP IS NO LONGER SUPPORTED If you need support for WinXP, download release 15-MAR-2014 instead. FIX: Some minor issues NEW: Better visualisation of validation issues NEW: Printing CHG: Disabled Jumplist CHG: updated to .net 4.5, WinXP NO LONGER SUPPORTEDPerformance Analyzer for Microsoft Dynamics: DynamicsPerf 1.20: Version 1.20 Improved performance in PERFHOURLYROWDATA_VW Fixed error handling encrypted triggers Added logic ACTIVITYMONITORVW to handle Context_Info for Dynamics AX 2012 and above with this flag set on AOS Added logic to optional blocking to handle Context_Info for Dynamics AX 2012 and above with this flag set on AOS Added additional queries for investigating blocking Added logic to collect Baseline capture data (NOTE: QUERY_STATS table has entire procedure cache for that db during...Toolbox for Dynamics CRM 2011/2013: XrmToolBox (v1.2014.5.28): XrmToolbox improvement XrmToolBox updates (v1.2014.5.28)Fix connecting to a connection with custom authentication without saved password Tools improvement New tool!Solution Components Mover (v1.2014.5.22) Transfer solution components from one solution to another one Import/Export NN relationships (v1.2014.3.7) Allows you to import and export many to many relationships Tools updatesAttribute Bulk Updater (v1.2014.5.28) Audit Center (v1.2014.5.28) View Layout Replicator (v1.2014.5.28) Scrip...Microsoft Ajax Minifier: Microsoft Ajax Minifier 5.10: Fix for Issue #20875 - echo switch doesn't work for CSS CSS should honor the SASS source-file comments JS should allow multi-line comment directivesClosedXML - The easy way to OpenXML: ClosedXML 0.71.1: More performance improvements. It's faster and consumes less memory.Kartris E-commerce: Kartris v2.6002: Minor release: Double check that Logins_GetList sproc is present, sometimes seems to get missed earlier if upgrading which can give error when viewing logins page Added CSV and TXT export option; this is not Google Products compatible, but can give a good base for creating a file for some other systems such as Amazon Fixed some minor combination and options issues to improve interface back and front Turn bitcoin and some other gateways off by default Minor CSS changes Fixed currenc...SimCityPak: SimCityPak 0.3.1.0: Main New Features: Fixed Importing of Instance Names (get rid of the Dutch translations) Added advanced editor for Decal Dictionaries Added possibility to import .PNG to generate new decals Added advanced editor for Path display entriesTiny Deduplicator: Tiny Deduplicator 1.0.1.0: Increased version number to 1.0.1.0 Moved all options to a separate 'Options' dialog window. Allows the user to specify a selection strategy which will help when dealing with large numbers of duplicate files. Available options are "None," "Keep First," and "Keep Last"Player Framework by Microsoft: Player Framework for Windows and WP v2.0: Support for new Universal and Windows Phone 8.1 projects for both Xaml and JavaScript projects. See a detailed list of improvements, breaking changes and a general overview of version 2 ADDITIONAL DOWNLOADSSmooth Streaming Client SDK for Windows 8 Applications Smooth Streaming Client SDK for Windows 8.1 Applications Smooth Streaming Client SDK for Windows Phone 8.1 Applications Microsoft PlayReady Client SDK for Windows 8 Applications Microsoft PlayReady Client SDK for Windows 8.1 Applicat...TerraMap (Terraria World Map Viewer): TerraMap 1.0.6: Added support for the new Terraria v1.2.4 update. New items, walls, and tiles Added the ability to select multiple highlighted block types. Added a dynamic, interactive highlight opacity slider, making it easier to find highlighted tiles with dark colors (and fixed blurriness from 1.0.5 alpha). Added ability to find Enchanted Swords (in the stone) and Water Bolt books Fixed Issue 35206: Hightlight/Find doesn't work for Demon Altars Fixed finding Demon Hearts/Shadow Orbs Fixed inst...New ProjectsBooki-Framework: A very super simple framework for develop application on .net (University assignment)C# Datalayer Using Stored Procedures for CRUD Operations: A C# .net data layer that uses stored procedures for crud operations working on any database, while still utilizing object orientated design practices.CoMaSy: Contact Management InfoComposite Iconote: Composite Iconote is a .NET composite. This is a Final Project of Component-Oriented Programming subject in Duta Wacana Christian University YogyakartaCredit Component: CreditComponent give you more attractive view to present who is the developer from any desktop software, many animation can introduce whom the developer isDaQiu: ?????????,??????????????????Database Helper: Rapid Development of CRUD Operationdi_academy_test: Test projectEasy Rent - Car rental software: Easy Rent software is an open source vehicle rental software.Excel Trader: Current project aims to provide an Excel(TM) interface through ExcelDNA for the IBRx, QFIXRx and SusicoTrader API.FXJ Learning Project: This is a learning project with TFS serviceImage View Slider: This is a .NET component. We create this using VB.NET. Here you can use an Image Viewer with several properties to your application form. Try this out!Indonesian Red-Letter Day Calendar: This is an Indonesian version of Red Letter Day Calendar, a final project for Component Oriented Programming course in Duta Wacana Christian University.jquery learning: jquery learningMakePanoForGoogle: Converts Panorama created by Microsoft ICE to format compatible to Google ViewsPWA_AppWeb: This page and all its content were developed by José Brazeta, Luis Carta and João Martins as an assignment for Advanced Web Programing (AEP).SoccerEvaluator: Proyecto para realizar evaluaciones de marcadores de futbolTooltip Web Preview: WebPreview is a component which was made to preview a web page before the link is clicked.Traditional Calendar Component: Hello this is a component which will help you to convert BC calendar to Javanese Calendar and Chinese Calendar. Hope this can help you on developing aps :)Typed YetiBowl The Game: Typescript Version of Yetibowl, intended for comparing Yetibowl in Javascript vs Typescript

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  • Stale statistics on a newly created temporary table in a stored procedure can lead to poor performance

    - by sqlworkshops
    When you create a temporary table you expect a new table with no past history (statistics based on past existence), this is not true if you have less than 6 updates to the temporary table. This might lead to poor performance of queries which are sensitive to the content of temporary tables.I was optimizing SQL Server Performance at one of my customers who provides search functionality on their website. They use stored procedure with temporary table for the search. The performance of the search depended on who searched what in the past, option (recompile) by itself had no effect. Sometimes a simple search led to timeout because of non-optimal plan usage due to this behavior. This is not a plan caching issue rather temporary table statistics caching issue, which was part of the temporary object caching feature that was introduced in SQL Server 2005 and is also present in SQL Server 2008 and SQL Server 2012. In this customer case we implemented a workaround to avoid this issue (see below for example for workarounds).When temporary tables are cached, the statistics are not newly created rather cached from the past and updated based on automatic update statistics threshold. Caching temporary tables/objects is good for performance, but caching stale statistics from the past is not optimal.We can work around this issue by disabling temporary table caching by explicitly executing a DDL statement on the temporary table. One possibility is to execute an alter table statement, but this can lead to duplicate constraint name error on concurrent stored procedure execution. The other way to work around this is to create an index.I think there might be many customers in such a situation without knowing that stale statistics are being cached along with temporary table leading to poor performance.Ideal solution is to have more aggressive statistics update when the temporary table has less number of rows when temporary table caching is used. I will open a connect item to report this issue.Meanwhile you can mitigate the issue by creating an index on the temporary table. You can monitor active temporary tables using Windows Server Performance Monitor counter: SQL Server: General Statistics->Active Temp Tables. The script to understand the issue and the workaround is listed below:set nocount onset statistics time offset statistics io offdrop table tab7gocreate table tab7 (c1 int primary key clustered, c2 int, c3 char(200))gocreate index test on tab7(c2, c1, c3)gobegin trandeclare @i intset @i = 1while @i <= 50000begininsert into tab7 values (@i, 1, ‘a’)set @i = @i + 1endcommit trangoinsert into tab7 values (50001, 1, ‘a’)gocheckpointgodrop proc test_slowgocreate proc test_slow @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_slow 1godbcc dropcleanbuffersgo–high reads that are not expected for parameter ’2'exec test_slow 2godrop proc test_with_recompilegocreate proc test_with_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_with_recompile 1godbcc dropcleanbuffersgo–high reads that are not expected for parameter ’2'–low reads on 3rd execution as expected for parameter ’2'exec test_with_recompile 2godrop proc test_with_alter_table_recompilegocreate proc test_with_alter_table_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)–to avoid caching of temporary tables one can create a constraint–but this might lead to duplicate constraint name error on concurrent usagealter table #temp1 add constraint test123 unique(c1)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_with_alter_table_recompile 1godbcc dropcleanbuffersgo–low reads as expected for parameter ’2'exec test_with_alter_table_recompile 2godrop proc test_with_index_recompilegocreate proc test_with_index_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)–to avoid caching of temporary tables one can create an indexcreate index test on #temp1(c1)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgoset statistics time onset statistics io ondbcc dropcleanbuffersgo–high reads as expected for parameter ’1'exec test_with_index_recompile 1godbcc dropcleanbuffersgo–low reads as expected for parameter ’2'exec test_with_index_recompile 2go

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  • How can I change the wallpaper using a Python script?

    - by furtelwart
    I want to change my wallpaper in Ubuntu 11.10 (with Unity) in a small Python script. I found the possibility to change it via the gconf-editor in /desktop/gnome/background/picture_filename. With python-gconf, I'm able to change the necessary values. Apparently, the gconf string is not read out. If I change it (either via a script or via gconf-editor), the wallpaper remains and in the menu of "Change wallpaper", the old wallpaper is shown. How am I able to change the wallpaper for Unity via a Python script? The following code does work. Apparently, the gsettings are only applied, if some Gtk code is executed. #!/usr/bin/python # -*- coding: utf-8 -*- from gi.repository import Gtk, Gio class BackgroundChanger(): SCHEMA = 'org.gnome.desktop.background' KEY = 'picture-uri' def change_background(self, filename): gsettings = Gio.Settings.new(self.SCHEMA) print(gsettings.get_string(self.KEY)) print(gsettings.set_string(self.KEY, "file://" + filename)) Gtk.Window() print(gsettings.get_string(self.KEY)) if __name__ == "__main__": BackgroundChanger().change_background("/home/user/existing.jpg")

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  • Oracle NoSQL Database Exceeds 1 Million Mixed YCSB Ops/Sec

    - by Charles Lamb
    We ran a set of YCSB performance tests on Oracle NoSQL Database using SSD cards and Intel Xeon E5-2690 CPUs with the goal of achieving 1M mixed ops/sec on a 95% read / 5% update workload. We used the standard YCSB parameters: 13 byte keys and 1KB data size (1,102 bytes after serialization). The maximum database size was 2 billion records, or approximately 2 TB of data. We sized the shards to ensure that this was not an "in-memory" test (i.e. the data portion of the B-Trees did not fit into memory). All updates were durable and used the "simple majority" replica ack policy, effectively 'committing to the network'. All read operations used the Consistency.NONE_REQUIRED parameter allowing reads to be performed on any replica. In the past we have achieved 100K ops/sec using SSD cards on a single shard cluster (replication factor 3) so for this test we used 10 shards on 15 Storage Nodes with each SN carrying 2 Rep Nodes and each RN assigned to its own SSD card. After correcting a scaling problem in YCSB, we blew past the 1M ops/sec mark with 8 shards and proceeded to hit 1.2M ops/sec with 10 shards.  Hardware Configuration We used 15 servers, each configured with two 335 GB SSD cards. We did not have homogeneous CPUs across all 15 servers available to us so 12 of the 15 were Xeon E5-2690, 2.9 GHz, 2 sockets, 32 threads, 193 GB RAM, and the other 3 were Xeon E5-2680, 2.7 GHz, 2 sockets, 32 threads, 193 GB RAM.  There might have been some upside in having all 15 machines configured with the faster CPU, but since CPU was not the limiting factor we don't believe the improvement would be significant. The client machines were Xeon X5670, 2.93 GHz, 2 sockets, 24 threads, 96 GB RAM. Although the clients had 96 GB of RAM, neither the NoSQL Database or YCSB clients require anywhere near that amount of memory and the test could have just easily been run with much less. Networking was all 10GigE. YCSB Scaling Problem We made three modifications to the YCSB benchmark. The first was to allow the test to accommodate more than 2 billion records (effectively int's vs long's). To keep the key size constant, we changed the code to use base 32 for the user ids. The second change involved to the way we run the YCSB client in order to make the test itself horizontally scalable.The basic problem has to do with the way the YCSB test creates its Zipfian distribution of keys which is intended to model "real" loads by generating clusters of key collisions. Unfortunately, the percentage of collisions on the most contentious keys remains the same even as the number of keys in the database increases. As we scale up the load, the number of collisions on those keys increases as well, eventually exceeding the capacity of the single server used for a given key.This is not a workload that is realistic or amenable to horizontal scaling. YCSB does provide alternate key distribution algorithms so this is not a shortcoming of YCSB in general. We decided that a better model would be for the key collisions to be limited to a given YCSB client process. That way, as additional YCSB client processes (i.e. additional load) are added, they each maintain the same number of collisions they encounter themselves, but do not increase the number of collisions on a single key in the entire store. We added client processes proportionally to the number of records in the database (and therefore the number of shards). This change to the use of YCSB better models a use case where new groups of users are likely to access either just their own entries, or entries within their own subgroups, rather than all users showing the same interest in a single global collection of keys. If an application finds every user having the same likelihood of wanting to modify a single global key, that application has no real hope of getting horizontal scaling. Finally, we used read/modify/write (also known as "Compare And Set") style updates during the mixed phase. This uses versioned operations to make sure that no updates are lost. This mode of operation provides better application behavior than the way we have typically run YCSB in the past, and is only practical at scale because we eliminated the shared key collision hotspots.It is also a more realistic testing scenario. To reiterate, all updates used a simple majority replica ack policy making them durable. Scalability Results In the table below, the "KVS Size" column is the number of records with the number of shards and the replication factor. Hence, the first row indicates 400m total records in the NoSQL Database (KV Store), 2 shards, and a replication factor of 3. The "Clients" column indicates the number of YCSB client processes. "Threads" is the number of threads per process with the total number of threads. Hence, 90 threads per YCSB process for a total of 360 threads. The client processes were distributed across 10 client machines. Shards KVS Size Clients Mixed (records) Threads OverallThroughput(ops/sec) Read Latencyav/95%/99%(ms) Write Latencyav/95%/99%(ms) 2 400m(2x3) 4 90(360) 302,152 0.76/1/3 3.08/8/35 4 800m(4x3) 8 90(720) 558,569 0.79/1/4 3.82/16/45 8 1600m(8x3) 16 90(1440) 1,028,868 0.85/2/5 4.29/21/51 10 2000m(10x3) 20 90(1800) 1,244,550 0.88/2/6 4.47/23/53

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  • Override Built-In Maverick Keyboard Shortcuts

    - by jrc03c
    Having used the Command+M keyboard shortcut to minimize windows in OS X, I'd like to use the same functionality in Ubuntu 10.10. When I try, though, it only brings up the "communications" section of the indicator applet; like so: In the Keyboard Shortcuts preferences, I have set as the minimize shortcut Mod4+M, which I got by capturing the Apple Command key and the M key. I find no other shortcut using this key combination in Keyboard Shortcuts, and yet I cannot get the window to minimize when using it. Does anyone know how to override Ubuntu's default usage of this key combination? Thanks!

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  • How to take screenshot while a menu is open [closed]

    - by Anwar
    Possible Duplicate: How to take a screenshot of a whole desktop with app menu selection? I recently wanted to take a screen shot of a nautilus menu to provide an image to the answer of a nautilus related question. (I was looking for it). But when I opened up the menu and press the prtsrc key, nothing happened. I have also tried Shift+PrtSrc Key and Alt+PrtScr key. Result was the same. My question is : Is is not possible not take a screenshot while you have a menu open?. Is it bug or not? Note: To test this, just right-click on the desktop, and press prtsrc key.

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  • How to implement smart card authentication with a .NET Fat client?

    - by John Nevermore
    I know very little about smart card authentication in general so please point out or correct me if anything below doesn't make sense. Lets say i have: A Certificate Authority "X"-s smart card (non-exportable private key) Drivers for that smart card written in C A smart card reader CA-s authentication OCSP web service A requirement to implement user authentication in a .NET fat client application via a smart card, that was given out by the CA "X". I tried searching info on the web but no prevail. What would the steps be ? My first thought was: Set up a web service, that would allow saving of (for example) scores of a ping pong game for each user. Each time someone tries to submit a score via the client application, he can only do so by inserting the smart card into the reader. Then the public key is read from the smart card by native c calls through .NET and sent to my custom web service, which in return uses the CA-s authentication OCSP web service to prove the validity of the public key/public certificate (?). If the public key is okay and valid, encrypt a random sequence of bytes with the public key and send it to the client application. If the client application sends back the correctly decrypted random sequence of bytes along with the score of the ping pong game, then the score is saved in the database for the given user. My question is, is this the correct way to do it ? What else should i know about smart card authentication ?

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  • Can we compare programming languages ergonomically?

    - by Nick Rosencrantz
    For instance, would Python be a more ergonomic programming language since it doesn't force you to make curly braces which requires the AltGr key. Also Python usually requires less code to achieve the same or am I being biased towards Python and PHP actually is an ergonomical and comfortable language despite forcing the programmer to use the AltGr key? Isn't forcing the programmer to use the AltGr key not very ergonomical?

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  • International Dvorak keyboard doesn't trigger hot-keys

    - by akurtser
    I'm using the Engilsh-Dvorak keyboard-layout; My second keyboard language is Hebrew, which has nothing to do with Dvorak but the hot keys (e.g if I'm writing a document in Hebrew and want to make some bold text using Ctrl+b). The default Hebrew keyboard that comes with Windows (7 and below) has a shift mode which matches each Hebrew character with its matching English QWERTY character ). Obviously I'd want to use the Dvorak corresponding key rather than the QWERTY one, so I created a Hebrew-Dvorak keyboard with a software called Keyboard Layout Manager (KLM) which creates new keyboard layouts DLLs. It works just fine for the shift key, however, Ctrl-key triggered hot-keys (e.g Ctrl+l in FF) are being matched to the corresponding QWERTY key. I've examined the properly working English-Dvorak layout using KLM and in it's "Ctrl+ pressed" view, there isn't any character that's matched to any key but still I tried to encode the Hebrew Ctrl+ pressed keys to work with their matching Dvorak keys, yet it had no effect.

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  • If all variables are a subset of the superkey, is the database design 5NF? [migrated]

    - by Lukazoid
    I have a table called LogMessages, which has the following columns: Level A numeric value which represents Trace, Debug, Info, Warning, Error or Fatal Time A UTC time Message Foreign key to a Messages table Source Foreign key to a Sources table User Foreign key to a Users table From what I can see, all of these columns are a part of the super key; if any single value differs to an existing row, a new row can be created. My question is, does this design comply to fifth normal form? I am unsure as some groups of data will be repeating, however I don't believe this violates 5NF? (correct me if I'm wrong)

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  • Override Built-In Maverick Keyboard Shortcuts

    - by jrc03c
    Having used the Command+M keyboard shortcut to minimize windows in OS X, I'd like to use the same functionality in Ubuntu 10.10. When I try, though, it only brings up the "communications" section of the indicator applet; like so: In the Keyboard Shortcuts preferences, I have set as the minimize shortcut "Mod4+M", which I got by capturing the Apple "Command" key and the "M" key. I find no other shortcut using this key combination in Keyboard Shortcuts, and yet I cannot get the window to minimize when using it. Does anyone know how to override Ubuntu's default usage of this key combination? Thanks!

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  • Powershell: Get-Framework-Versions.

    - by marc dekeyser
    This function will use the test-key function posted earlier. It will check which .NET frameworks are installed (currently only checking for .NET 4.0) but can be easily adapted and/or expanded. function Get-Framework-Versions(){    $installedFrameworks = @()    if(Test-Key "HKLM:\Software\Microsoft\NET Framework Setup\NDP\v4\Client" "Install") { $installedFrameworks += "4.0c" }    if(Test-Key "HKLM:\Software\Microsoft\NET Framework Setup\NDP\v4\Full" "Install") { $installedFrameworks += "4.0" }            return $installedFrameworks}

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  • What is A Keyword Enriched Article? - And is it Important For Your Business?

    Surely many of you will have the idea about the term "Key word Enriched Article" but certainly many of you will be unfamiliar with this term. So I will try to share my knowledge with you people in simple words. In a simple word we can say articles which contain keywords or key phrases which match the words type in any search engine are Key word Enriched Articles.

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  • Applying DDD principles in a RESTish web service

    - by Andy
    I am developing an RESTish web service. I think I got the idea of the difference between aggregation and composition. Aggregation does not enforce lifecycle/scope on the objects it references. Composition does enforce lifecycle/scope on the objects it contain/own. If I delete a composite object then all the objects it contain/own are deleted as well, while the deleting an aggregate root does not delete referenced objects. 1) If it is true that deleting aggregate roots does not necessary delete referenced objects, what sense does it make to not have a repository for the references objects? Or are aggregate roots as a term referring to what is known as composite object? 2) When you create an web service you will have multiple endpoints, in my case I have one entity Book and another named Comment. It does not make sense to leave the comments in my application if the book is deleted. Therefore, book is a composite object. I guess I should not have a repository for comments since that would break the enforcement of lifecycle and rules that the book class may have. However I have URL such as (examples only): GET /books/1/comments POST /books/1/comments Now, if I do not have a repository for comments, does that mean I have to load the book object and then return the referenced comments? Am I allowed to return a list of Comment entities from the BookRepository, does that make sense? The repository for Book may eventually become rather big with all sorts of methods. Am I allowed to write JPQL (JPA queries) that targets comments and not books inside the repository? What about pagination and filtering of comments. When adding a new comment triggered by the POST endpoint, do you need to load the book, add the comment to the book, and then update the whole book object? What I am currently doing is having a own CommentRepository, even though the comments are deleted with the book. I could need some direction on how to do it correct. Since you are exposing not only root objects in RESTish services I wonder how to handle this at the backend. I am using Hibernate and Spring.

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  • SSH asks for password

    - by user1435470
    I have already : Installed the server Generated the pub/pri keys with -P "" Copied the id_rsa.pub to authorized_keys ssh localhost answered "yes", copied to known_hosts tried ssh localhost still asks for password Output: hduser@hduser1-desktop:~$ ssh -v localhost OpenSSH_5.3p1 Debian-3ubuntu7, OpenSSL 0.9.8k 25 Mar 2009 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug1: Connecting to localhost [127.0.0.1] port 22. debug1: Connection established. debug1: identity file /home/hduser/.ssh/identity type -1 debug1: identity file /home/hduser/.ssh/id_rsa type 1 debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048 debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048 debug1: identity file /home/hduser/.ssh/id_dsa type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3p1 Debian- 3ubuntu7 debug1: match: OpenSSH_5.3p1 Debian-3ubuntu7 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.3p1 Debian-3ubuntu7 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Host 'localhost' is known and matches the RSA host key. debug1: Found key in /home/hduser/.ssh/known_hosts:3 debug1: ssh_rsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,password debug1: Next authentication method: publickey debug1: Offering public key: /home/hduser/.ssh/id_rsa debug1: Authentications that can continue: publickey,password debug1: Trying private key: /home/hduser/.ssh/identity debug1: Trying private key: /home/hduser/.ssh/id_dsa debug1: Next authentication method: password Any suggestions ? Cheers

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  • How do Unity 12.04/Compiz bindings really work?

    - by Daniel
    There is a bewildering array of places to set bindings, all inconsistent with one another. E.g. in Unity's System Settings having the Ctrl-key highlight the mouse position is an on/off choice. I like the feature, but not on such a prominent key where I keep activating it accidentally. The keyboard shortcuts allow only one binding per command, where I might like a convenient one on the external keyboard and an emergency alternative for when I'm on the road. Keyboard custom shortcuts has a nice interface, but allows only key bindings — besides it doesn't seem to work for me. So I activated CCSM Commands. There I have the choice of key-, mouse- and/or edge bindings. Whereas some places in CCSM offers only one or two of these binding possibilities, randomly at the whim of the programmer. I have not found a way to differentiate a mouse-drag from a click. E.g. I want <SuperMouse1-drag anywhere on a window to move it, while if I don't drag, it should be raise-lower. On the title bar I want the same without needing the <Super key. Now I find raise-lower only in System Settings where I can't assign a mouse binding. If therefore in CCSM I fallback to only lower and put move on the same binding, the window already gets lowered on mouse down, and I can then invisibly move it. Very useful! I have <Altasciicircum get in the way of an Emacs binding, with some to me useless popup overlay. I can find it nowhere, so I can't turn it off. So how can I go without these frontends until they have matured, and instruct Compiz directly, for example in the way Emacs or Sawfish have keymaps, and separate ones for each context, with inheritance?

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