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  • Easily Customize Internet Explorer 9 Using IE9 Tweaker Plus

    - by Lori Kaufman
    If you use Internet Explorer 9, we found a useful program, called IE Tweaker Plus, that allows you to easily tweak and customize over 27 settings in the browser, as well as create customized IE9 shortcuts that automatically open IE in InPrivate mode. IE9 Tweaker Plus does not need to be installed. To run it, simply extract the .zip file you downloaded (see the link at the end of this article) and double-click on the .exe file. If the User Account Control dialog box displays, click Yes to continue. HTG Explains: How Windows 8′s Secure Boot Feature Works & What It Means for Linux Hack Your Kindle for Easy Font Customization HTG Explains: What Is RSS and How Can I Benefit From Using It?

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  • Best practices when creating/modeling databases?

    - by Oscar Mederos
    I learned at the University some steps to model a database: Model the problem using the Extended Entity-Relationship Model. Extract the functional dependencies Apply some algorithms to normalize the database (3NF or Boyce-Codd) Create the database I'm studying Computer Science and since I received that course I'm wondering if I always need to do those steps when creating a complex database for an specified problem. For example, do PHP / .NET / .. programmers always do that? or there are some tools to simplify that process, maybe using another way of represent the problem instead of the EERM?

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  • Microsoft Technical Computing

    In the past I have described the team I belong to here at Microsoft (Parallel Computing Platform) in terms of contributing to Visual Studio and related products, e.g. .NET Framework. To be more precise, our team is part of the Technical Computing group, which is still part of the Developer Division. This was officially announced externally earlier this month in an exec email (from Bob Muglia, the president of STB, to which DevDiv belongs). Here is an extract: " As we build the Technical...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Best practices when creating/modeling databases?

    - by Oscar Mederos
    Hello, I learned at the University some steps to model a database: Model the problem using the Extended Entity-Relationship Model. Extract the functional dependencies Apply some algorithms to normalize the database (3NF or Boyce-Codd) Create the database I'm studying Computer Science and since I received that course I'm wondering if I always need to do those steps when creating a complex database for an specified problem. For example, do PHP / .NET / .. programmers always do that? or there are some tools to simplify that process, maybe using another way of represent the problem instead of the EERM?

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  • Ever helpful Windows&hellip;

    - by John Breakwell
    I’m doing some troubleshooting for a relative and asked them to send me a zipped copy of their registry which they dutifully did. When I tried to extract the registry file, though, Windows jumped in the way and said “No”. This made sense as registry files are dangerous things in the hands of the ignorant. So I clicked the link to see if it would tell me how to get at the reg file but found the result less than helpful. So off to the Internet and found an excellent answer on how to get round this: Now on to the much harder part of fixing the original problems.

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  • Alien deletes .deb when converting from .rpm

    - by Stann
    I'm trying to convert .rpm to .deb using alien. sudo alien -k libtetra-1.0.0-2.i386.rpm Alien says that: libtetra-1.0.0-2.i386.deb generated But when I check the folder - there is just original .rpm and no .deb. Also - I can see that for a split second there is a .deb file in a folder. so it looks like alien create .deb and deletes it right away. I suspect that it's maybe because I run 64 bit os and package is 32? Can somebody explain why alien deletes .deb automatically? Verbose output: LANG=C rpm -qp --queryformat %{NAME} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{VERSION} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{RELEASE} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{ARCH} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{CHANGELOGTEXT} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{SUMMARY} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{DESCRIPTION} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{PREFIXES} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{POSTIN} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{POSTUN} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{PREUN} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{LICENSE} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qp --queryformat %{PREIN} libtetra-1.0.0-2.i386.rpm LANG=C rpm -qcp libtetra-1.0.0-2.i386.rpm rpm -qpi libtetra-1.0.0-2.i386.rpm LANG=C rpm -qpl libtetra-1.0.0-2.i386.rpm mkdir libtetra-1.0.0 chmod 755 libtetra-1.0.0 rpm2cpio libtetra-1.0.0-2.i386.rpm | lzma -t -q > /dev/null 2>&1 rpm2cpio libtetra-1.0.0-2.i386.rpm | (cd libtetra-1.0.0; cpio --extract --make-directories --no-absolute-filenames --preserve-modification-time) 2>&1 chmod 755 libtetra-1.0.0/./ chmod 755 libtetra-1.0.0/./usr chmod 755 libtetra-1.0.0/./usr/lib chown 0:0 libtetra-1.0.0//usr/lib/libtetra.so.1.0.0 chmod 755 libtetra-1.0.0//usr/lib/libtetra.so.1.0.0 mkdir libtetra-1.0.0/debian date -R date -R chmod 755 libtetra-1.0.0/debian/rules debian/rules binary 2>&1 libtetra_1.0.0-3_i386.deb generated find libtetra-1.0.0 -type d -exec chmod 755 {} ; rm -rf libtetra-1.0.0 Very Verbose output LANG=C rpm -qp --queryformat %{NAME} libtetra-1.0.0-2.i386.rpm libtetra LANG=C rpm -qp --queryformat %{VERSION} libtetra-1.0.0-2.i386.rpm 1.0.0 LANG=C rpm -qp --queryformat %{RELEASE} libtetra-1.0.0-2.i386.rpm 2 LANG=C rpm -qp --queryformat %{ARCH} libtetra-1.0.0-2.i386.rpm i386 LANG=C rpm -qp --queryformat %{CHANGELOGTEXT} libtetra-1.0.0-2.i386.rpm - First RPM Package LANG=C rpm -qp --queryformat %{SUMMARY} libtetra-1.0.0-2.i386.rpm Panasonic KX-MC6000 series Printer Driver for Linux. LANG=C rpm -qp --queryformat %{DESCRIPTION} libtetra-1.0.0-2.i386.rpm This software is Panasonic KX-MC6000 series Printer Driver for Linux. You can print from applications by using CUPS(Common Unix Printing System) which is the printing system for Linux. Other functions for KX-MC6000 series are not supported by this software. LANG=C rpm -qp --queryformat %{PREFIXES} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qp --queryformat %{POSTIN} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qp --queryformat %{POSTUN} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qp --queryformat %{PREUN} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qp --queryformat %{LICENSE} libtetra-1.0.0-2.i386.rpm GPL and LGPL (Version2) LANG=C rpm -qp --queryformat %{PREIN} libtetra-1.0.0-2.i386.rpm (none) LANG=C rpm -qcp libtetra-1.0.0-2.i386.rpm rpm -qpi libtetra-1.0.0-2.i386.rpm Name : libtetra Relocations: (not relocatable) Version : 1.0.0 Vendor: Panasonic Communications Co., Ltd. Release : 2 Build Date: Tue 27 Apr 2010 05:16:40 AM EDT Install Date: (not installed) Build Host: localhost.localdomain Group : System Environment/Daemons Source RPM: libtetra-1.0.0-2.src.rpm Size : 31808 License: GPL and LGPL (Version2) Signature : (none) URL : http://panasonic.net/pcc/support/fax/world.htm Summary : Panasonic KX-MC6000 series Printer Driver for Linux. Description : This software is Panasonic KX-MC6000 series Printer Driver for Linux. You can print from applications by using CUPS(Common Unix Printing System) which is the printing system for Linux. Other functions for KX-MC6000 series are not supported by this software. LANG=C rpm -qpl libtetra-1.0.0-2.i386.rpm /usr/lib/libtetra.so /usr/lib/libtetra.so.1.0.0 mkdir libtetra-1.0.0 chmod 755 libtetra-1.0.0 rpm2cpio libtetra-1.0.0-2.i386.rpm | lzma -t -q > /dev/null 2>&1 rpm2cpio libtetra-1.0.0-2.i386.rpm | (cd libtetra-1.0.0; cpio --extract --make-directories --no-absolute-filenames --preserve-modification-time) 2>&1 63 blocks chmod 755 libtetra-1.0.0/./ chmod 755 libtetra-1.0.0/./usr chmod 755 libtetra-1.0.0/./usr/lib chown 0:0 libtetra-1.0.0//usr/lib/libtetra.so.1.0.0 chmod 755 libtetra-1.0.0//usr/lib/libtetra.so.1.0.0 mkdir libtetra-1.0.0/debian date -R Mon, 07 Feb 2011 11:03:58 -0500 date -R Mon, 07 Feb 2011 11:03:58 -0500 chmod 755 libtetra-1.0.0/debian/rules debian/rules binary 2>&1 dh_testdir dh_testdir dh_testroot dh_clean -k -d dh_clean: No packages to build. dh_installdirs dh_installdocs dh_installchangelogs find . -maxdepth 1 -mindepth 1 -not -name debian -print0 | \ xargs -0 -r -i cp -a {} debian/ dh_compress dh_makeshlibs dh_installdeb dh_shlibdeps dh_gencontrol dh_md5sums dh_builddeb libtetra_1.0.0-2_i386.deb generated find libtetra-1.0.0 -type d -exec chmod 755 {} ; rm -rf libtetra-1.0.0 Resolution Oh well. It looks like it's perhaps a bug? or I don't know. I simply installed 32-bit version of Ubuntu in VirtualBox and converted package there. For some reason I couldn't convert 32-bit package in 64 OS. and that is that. If someone ever finds the reason ffor this behavior - plz. post somewhere in comments. Thanks

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  • SQL SERVER – SQL in Sixty Seconds – 5 Videos from Joes 2 Pros Series – SQL Exam Prep Series 70-433

    - by pinaldave
    Joes 2 Pros SQL Server Learning series is indeed fun. Joes 2 Pros series is written for beginners and who wants to build expertise for SQL Server programming and development from fundamental. In the beginning of the series author Rick Morelan is not shy to explain the simplest concept of how to open SQL Server Management Studio. Honestly the book starts with that much basic but as it progresses further Rick discussing about various advanced concepts from query tuning to Core Architecture. This five part series is written with keeping SQL Server Exam 70-433. Instead of just focusing on what will be there in exam, this series is focusing on learning the important concepts thoroughly. This book no way take short cut to explain any concepts and at times, will go beyond the topic at length. The best part is that all the books has many companion videos explaining the concepts and videos. Every Wednesday I like to post a video which explains something in quick few seconds. Today we will go over five videos which I posted in my earlier posts related to Joes 2 Pros series. Introduction to XML Data Type Methods – SQL in Sixty Seconds #015 The XML data type was first introduced with SQL Server 2005. This data type continues with SQL Server 2008 where expanded XML features are available, most notably is the power of the XQuery language to analyze and query the values contained in your XML instance. There are five XML data type methods available in SQL Server 2008: query() – Used to extract XML fragments from an XML data type. value() – Used to extract a single value from an XML document. exist() – Used to determine if a specified node exists. Returns 1 if yes and 0 if no. modify() – Updates XML data in an XML data type. node() – Shreds XML data into multiple rows (not covered in this blog post). [Detailed Blog Post] | [Quiz with Answer] Introduction to SQL Error Actions – SQL in Sixty Seconds #014 Most people believe that when SQL Server encounters an error severity level 11 or higher the remaining SQL statements will not get executed. In addition, people also believe that if any error severity level of 11 or higher is hit inside an explicit transaction, then the whole statement will fail as a unit. While both of these beliefs are true 99% of the time, they are not true in all cases. It is these outlying cases that frequently cause unexpected results in your SQL code. To understand how to achieve consistent results you need to know the four ways SQL Error Actions can react to error severity levels 11-16: Statement Termination – The statement with the procedure fails but the code keeps on running to the next statement. Transactions are not affected. Scope Abortion – The current procedure, function or batch is aborted and the next calling scope keeps running. That is, if Stored Procedure A calls B and C, and B fails, then nothing in B runs but A continues to call C. @@Error is set but the procedure does not have a return value. Batch Termination – The entire client call is terminated. XACT_ABORT – (ON = The entire client call is terminated.) or (OFF = SQL Server will choose how to handle all errors.) [Detailed Blog Post] | [Quiz with Answer] Introduction to Basics of a Query Hint – SQL in Sixty Seconds #013 Query hints specify that the indicated hints should be used throughout the query. Query hints affect all operators in the statement and are implemented using the OPTION clause. Cautionary Note: Because the SQL Server Query Optimizer typically selects the best execution plan for a query, it is highly recommended that hints be used as a last resort for experienced developers and database administrators to achieve the desired results. [Detailed Blog Post] | [Quiz with Answer] Introduction to Hierarchical Query – SQL in Sixty Seconds #012 A CTE can be thought of as a temporary result set and are similar to a derived table in that it is not stored as an object and lasts only for the duration of the query. A CTE is generally considered to be more readable than a derived table and does not require the extra effort of declaring a Temp Table while providing the same benefits to the user. However; a CTE is more powerful than a derived table as it can also be self-referencing, or even referenced multiple times in the same query. A recursive CTE requires four elements in order to work properly: Anchor query (runs once and the results ‘seed’ the Recursive query) Recursive query (runs multiple times and is the criteria for the remaining results) UNION ALL statement to bind the Anchor and Recursive queries together. INNER JOIN statement to bind the Recursive query to the results of the CTE. [Detailed Blog Post] | [Quiz with Answer] Introduction to SQL Server Security – SQL in Sixty Seconds #011 Let’s get some basic definitions down first. Take the workplace example where “Tom” needs “Read” access to the “Financial Folder”. What are the Securable, Principal, and Permissions from that last sentence? A Securable is a resource that someone might want to access (like the Financial Folder). A Principal is anything that might want to gain access to the securable (like Tom). A Permission is the level of access a principal has to a securable (like Read). [Detailed Blog Post] | [Quiz with Answer] Please leave a comment explain which one was your favorite video as that will help me understand what works and what needs improvement. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology, Video

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  • scrapy cannot find div on this website [on hold]

    - by Jaspal Singh Rathour
    I am very new at this and have been trying to get my head around my first selector can somebody help? i am trying to extract data from page http://groceries.asda.com/asda-webstore/landing/home.shtml?cmpid=ahc--ghs-d1--asdacom-dsk-_-hp#/shelf/1215337195041/1/so_false all the info under div class = listing clearfix shelfListing but i cant seem to figure out how to format response.xpath(). I have managed to launch scrapy console but no matter what I type in response.xpath() i cant seem to select the right node. I know it works because when I type response.xpath('//div[@class="container"]') I get a response but don't know how to navigate to the listsing cleardix shelflisting. I am hoping that once i get this bit I can continue working my way through the spider. Thank you in advance! PS I wonder if it is not possible to scan this site - is it possible for the owners to block spiders?

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  • Scrapy cannot find div on this website [on hold]

    - by Jaspal Singh Rathour
    I am very new at this and have been trying to get my head around my first selector can somebody help? i am trying to extract data from page http://groceries.asda.com/asda-webstore/landing/home.shtml?cmpid=ahc--ghs-d1--asdacom-dsk-_-hp#/shelf/1215337195041/1/so_false all the info under div class = listing clearfix shelfListing but i cant seem to figure out how to format response.xpath(). I have managed to launch scrapy console but no matter what I type in response.xpath() i cant seem to select the right node. I know it works because when I type response.xpath('//div[@class="container"]') I get a response but don't know how to navigate to the listsing cleardix shelflisting. I am hoping that once i get this bit I can continue working my way through the spider. Thank you in advance! PS I wonder if it is not possible to scan this site - is it possible for the owners to block spiders?

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  • Week in Geek: New Malware Steals Bitcoin Currency

    - by Asian Angel
    This week we learned how to easily change a dual-booting PC’s default OS, “extract audio from any video using VLC, sneak around paywalls, & delay Windows Live Mesh during boot”, shrink videos to fit an Android phone with VLC, fix damaged or broken audio cables, “decide between an ISO or TS folder, help Windows 7 remember folder locations, & convert books for the Kindle”, and more. Photo by Profound Whatever.How to Make and Install an Electric Outlet in a Cabinet or DeskHow To Recover After Your Email Password Is CompromisedHow to Clean Your Filthy Keyboard in the Dishwasher (Without Ruining it)

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  • OS Analytics with Oracle Enterprise Manager (by Eran Steiner)

    - by Zeynep Koch
    Oracle Enterprise Manager Ops Center provides a feature called "OS Analytics". This feature allows you to get a better understanding of how the Operating System is being utilized. You can research the historical usage as well as real time data. This post will show how you can benefit from OS Analytics and how it works behind the scenes. The recording of our call to discuss this blog is available here: https://oracleconferencing.webex.com/oracleconferencing/ldr.php?AT=pb&SP=MC&rID=71517797&rKey=4ec9d4a3508564b3Download the presentation here See also: Blog about Alert Monitoring and Problem Notification Blog about Using Operational Profiles to Install Packages and other content Here is quick summary of what you can do with OS Analytics in Ops Center: View historical charts and real time value of CPU, memory, network and disk utilization Find the top CPU and Memory processes in real time or at a certain historical day Determine proper monitoring thresholds based on historical data Drill down into a process details Where to start To start with OS Analytics, choose the OS asset in the tree and click the Analytics tab. You can see the CPU utilization, Memory utilization and Network utilization, along with the current real time top 5 processes in each category (click the image to see a larger version):  In the above screen, you can click each of the top 5 processes to see a more detailed view of that process. Here is an example of one of the processes: One of the cool things is that you can see the process tree for this process along with some port binding and open file descriptors. Next, click the "Processes" tab to see real time information of all the processes on the machine: An interesting column is the "Target" column. If you configured Ops Center to work with Enterprise Manager Cloud Control, then the two products will talk to each other and Ops Center will display the correlated target from Cloud Control in this table. If you are only using Ops Center - this column will remain empty. The "Threshold" tab is particularly helpful - you can view historical trends of different monitored values and based on the graph - determine what the monitoring values should be: You can ask Ops Center to suggest monitoring levels based on the historical values or you can set your own. The different colors in the graph represent the current set levels: Red for critical, Yellow for warning and Blue for Information, allowing you to quickly see how they're positioned against real data. It's important to note that when looking at longer periods, Ops Center smooths out the data and uses averages. So when looking at values such as CPU Usage, try shorter time frames which are more detailed, such as one hour or one day. Applying new monitoring values When first applying new values to monitored attributes - a popup will come up asking if it's OK to get you out of the current Monitoring Policy. This is OK if you want to either have custom monitoring for a specific machine, or if you want to use this current machine as a "Gold image" and extract a Monitoring Policy from it. You can later apply the new Monitoring Policy to other machines and also set it as a default Monitoring Profile. Once you're done with applying the different monitoring values, you can review and change them in the "Monitoring" tab. You can also click the "Extract a Monitoring Policy" in the actions pane on the right to save all the new values to a new Monitoring Policy, which can then be found under "Plan Management" -> "Monitoring Policies". Visiting the past Under the "History" tab you can "go back in time". This is very helpful when you know that a machine was busy a few hours ago (perhaps in the middle of the night?), but you were not around to take a look at it in real time. Here's a view into yesterday's data on one of the machines: You can see an interesting CPU spike happening at around 3:30 am along with some memory use. In the bottom table you can see the top 5 CPU and Memory consumers at the requested time. Very quickly you can see that this spike is related to the Solaris 11 IPS repository synchronization process using the "pkgrecv" command. The "time machine" doesn't stop here - you can also view historical data to determine which of the zones was the busiest at a given time: Under the hood The data collected is stored on each of the agents under /var/opt/sun/xvm/analytics/historical/ An "os.zip" file exists for the main OS. Inside you will find many small text files, named after the Epoch time stamp in which they were taken If you have any zones, there will be a file called "guests.zip" containing the same small files for all the zones, as well as a folder with the name of the zone along with "os.zip" in it If this is the Enterprise Controller or the Proxy Controller, you will have folders called "proxy" and "sat" in which you will find the "os.zip" for that controller The actual script collecting the data can be viewed for debugging purposes as well: On Linux, the location is: /opt/sun/xvmoc/private/os_analytics/collect If you would like to redirect all the standard error into a file for debugging, touch the following file and the output will go into it: # touch /tmp/.collect.stderr   The temporary data is collected under /var/opt/sun/xvm/analytics/.collectdb until it is zipped. If you would like to review the properties for the Analytics, you can view those per each agent in /opt/sun/n1gc/lib/XVM.properties. Find the section "Analytics configurable properties for OS and VSC" to view the Analytics specific values. I hope you find this helpful! Please post questions in the comments below. Eran Steiner

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  • SQL SERVER – Selecting Domain from Email Address

    - by pinaldave
    Recently I came across a quick need where I needed to retrieve domain of the email address. The email address is in the database table. I quickly wrote following script which will extract the domain and will also count how many email addresses are there with the same domain address. SELECT RIGHT(Email, LEN(Email) - CHARINDEX('@', email)) Domain , COUNT(Email) EmailCount FROM   dbo.email WHERE  LEN(Email) > 0 GROUP BY RIGHT(Email, LEN(Email) - CHARINDEX('@', email)) ORDER BY EmailCount DESC Above script will select the domain after @ character. Please note, if there is more than one @ character in the email, this script will not work as that email address is already invalid. Do you have any similar script which can do the same thing efficiently? Please post as a comment. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Oracle UPK and IBM Rational Quality Manager

    - by marc.santosusso
    Did you know that you can import UPK topics into IBM Rational Quality Manager (RQM) as Test Scripts? Attached below is a ZIP of files which contains a customized style (for all supported languages) for creating spreadsheets that are compatible with IBM Rational Quality Manager, a sample IBM Rational Quality Manager mapping file, and a best practice document. UPK_Best_Practices_-_IBM_Rational_Quality_Manager_Integration.zip Extract the files and open the best practice document (PDF file) file to get started. Please note that the IBM Rational Quality Manager publishing style (the ODARC file) include with the above download was created using the customization instructions found within the UPK documentation. That said, it is not currently an "official" feature of the product, but rather an example of what can be created through style customization. Stay tuned for more details. We hope that you find this to be useful and welcome your feedback!

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  • Swept AABB vs Line Segment 2D

    - by Larolaro
    I've really exhausted as much as Google has to give, I've spent a solid week googling every combination of words for an "AABBvsLine sweep", downloaded countless collision demos, dissected SAT intersection examples and an AABBvsAABB sweep trying to figure out how to approach this. I've not found a single thing covering this specific pairing. Can anyone shed any light on how to get the hit time of a swept AABB vs a Line segment in 2D? I'm still getting familiar with the SAT but I do know how to implement it to a degree, I'm just not sure how to extract the hit time from the velocity in the non axis aligned separating axes for the sweep. I really would appreciate anything at the moment, some code or even some helpful links, I'm at my wits end!

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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • How to Convert an MP4 Video into an MP3 Audio File

    - by Erez Zukerman
    MP4 is a widely-used video format; you can grab MP4 files off YouTube, Vimeo, and many other online video websites. But what if you have a video of a song you love, and want to extract just the music? Read on to see two different ways to do just that. Latest Features How-To Geek ETC Have You Ever Wondered How Your Operating System Got Its Name? Should You Delete Windows 7 Service Pack Backup Files to Save Space? What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 Dim an Overly Bright Alarm Clock with a Binder Divider Preliminary List of Keyboard Shortcuts for Unity Now Available Bring a Touch of the Wild West to Your Desktop with the Rango Theme for Windows 7 Manage Your Favorite Social Accounts in Chrome and Iron with Seesmic E.T. II – Extinction [Fake Movie Sequel Video] Remastered King’s Quest Games Offer Classic Gaming on Modern Machines

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  • Ops Center zip documentation

    - by Owen Allen
    If you're operating in a dark site, or are otherwise without easy access to the internet, it can be tricky to get access to the docs. The readme comes along with the product, but that's not exactly the same as the whole doc library. Well, we've put a zip file with the whole doc library contents up on the main doc page. So, if you are in a site without internet access, you can get the zip, extract it, and have a portable version of the site, including the pdf and html versions of all of the docs.

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  • What are best practices when giving a presentation to programmers?

    - by blunders
    I've watched 50 plus presentations on programming topics, although most have been online; example, Google Tech Talks -- and have ad-hoc experience on what formats work for programmers, or practices to take into account when presenting to a group of programmers. That said, I'm open to any suggestions, but here's some topic of the top of my head: Programming Jokes, Images, etc. Posting Code for download Contact Info Collecting feedback Presenting Code on Screen If it matters, in this case -- I'm giving a presentation on using a scripting language to extract, transform and load data to a local user group who's focus is the scripting language; Ruby in this case. Questions, feedback, requests -- just comment, thanks!!

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  • I need to develop a parser. Can I use Lex and Yacc for the purpose?

    - by Scrooge
    I need to extract very particular data from log files(of different types and formats). Since I am a recent college passout; my mind ran to using Lex and Yacc for the purpose. Now I have the following Questions 1. Will it be legal to do so ? (This product I am working for belongs to one of the biggest tech companies in the world.) 2. Also ; I would like to know if I am being too afraid to write my own parser? 3. How can I use Lex and Yacc if my product is Windows based? Please tell me if you need any clarification or extra information.

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  • VOTE by 20 June for OpenWorld Talk on OWB with Non-Oracle Sources

    - by antonio romero
    OWB/ODI Linkedin Group member Suraj Bang has offered a topic through OpenWorld 2010 Suggest-a-Session at Oracle Mix: Extend ETL to Heterogeneous and Unstructured Data Sources with OWB 11gR2 To vote for this talk to appear, click through to: http://bit.ly/owb_km_openworld and click on the "Vote" button. Abstract follows: Beyond basic Oracle-to-Oracle ETL, data warehousing customers need to integrate data from multiple data sources spanning multiple database vendors, file formats(csv, xml, html) and unstructured data sources like pdf's and log files. This session describes experiences extending OWB 11gR2 to extract data from Postgres, SQL Server, MySQL and Sybase, PDF documents, and more for a major banking client's data warehousing project supporting IT operations. This included metadata extraction, custom knowledge module-based ETL and replacing ad-hoc perl and java extraction code with a manageable ETL solution built on OWB's extensible plaform. Note: You must vote for at least two other talks for your vote to count, so if you haven’t already picked your three, also consider: Case Study: Real-Time data warehousing and fraud detection with Oracle 11gR2.

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  • Methods to Manage/Document "one-off" Reports

    - by Jason Holland
    I'm a programmer that also does database stuff and I get a lot of so-called one-time report requests and recurring report requests. I work at a company that has a SQL Server database that we integrate third-party data with and we also have some third-party vendors that we have to use their proprietary reporting system to extract data in flat file format from that we don't integrate into SQL Server for security reasons. To generate many of these reports I have to query data from various systems, write small scripts to combine data from the separate systems, cry, pull my hair, curse the last guy's name that made the report before me, etc. My question is, what are some good methods for documenting the steps taken to generate these reports so the next poor soul that has to do them won't curse my name? As of now I just have a folder with subfolders per project with the selects and scripts that generated the last report but that seems like a "poor man's" solution. :)

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  • Best way to distribute graphics, audio and levels with an SDL game?

    - by Kristopher
    I'm working on finishing up a game written in C++ with SDL I've been working on for awhile, and I'm starting to ponder how I'm going to distribute it. It has hundreds of images that are loaded and used throughout the game, as well as a couple dozen .wav files for audio effects. What is the best way to distribute these? Should I just include the folders with all the files? Or is there a way I can package them into a single file, then open and extract them in my application? What's the best way to go about this?

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  • Ajax does not send the data to my php file [migrated]

    - by Mert METIN
    I try to send my data to php file but does not work. This my ajax file var artistIds = new Array(); $(".p16 input:checked").each(function(){ artistIds.push($(this).attr('id')); }); $.post('/json/crewonly/deleteDataAjax2', { artistIds: artistIds },function(response){ if(response == 'ok') alert('dolu'); elseif (response == 'error') alert('bos'); }); and this is my php public function deleteDataAjax2() { extract($_POST); if (isset($artistIds)) $this->sendJSONResponse('ok'); else $this->sendJSONResponse('error'); } However, my artistIds in php side is null. Why ?

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  • ~/.bashrc return can only 'return' from a function or sourced script

    - by Timothy
    I am trying to setup a OpenStack box to have a look at OpenStack Object Storage (Swift). Looking through the web I found this link; http://swift.openstack.org/development_saio.html#loopback-section I followed the instructions line by line but stuck on step 7 in the "Getting the code and setting up test environment" section. When I execute ~/.bashrc I get; line 6: return: can only 'return' from a function or sourced script. Below is the Line 6 extract from ~/.bashrc. My first reaction is to comment this line out, but I dont know what it does. Can anyone help? #If not running interactively, dont't do anything [ -z "$PS1" ] && return I'm running Ubuntu 12.04 as a VM on Hyper-v if knowing that is useful.

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  • How can I find a position between 4 vertices in a fragment shader?

    - by c4sh
    I'm creating a shader with SharpDX (DirectX11 in C#) that takes a segment (2 points) from the output of a Vertex Shader and then passes them to a Geometry Shader, which converts this line into a rectangle (4 points) and assigns the four corners a texture coordinate. After that I want a Fragment Shader (which recieves the interpolated position and the interpolated texture coordinates) that checks the depth at the "spine of the rectangle" (that is, in the line that passes through the middle of the rectangle. The problem is I don't know how to extract the position of the corresponding fragment at the spine of the rectangle. This happens because I have the texture coordinates interpolated, but I don't know how to use them to get the fragment I want, because the coordinate system of a) the texture and b) the position of my fragment in screen space are not the same. Thanks a lot for any help.

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