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• Is it possible to guarantee a unique id for multiple items using the same id variable at a point in

  - by Scarface

  First of all, do not be overwhelmed by the long code, I just put it for reference...I have a function that preg_replaces content and puts it in a jquery dialog box with a matching open-link. For example, if there is a paragraph with two matches, they will be put inside two divs, and a jquery dialog function will be echoed twice; one for each div. While this works for one match, if there are multiple matches, it does not. I am not sure how to distribute unique ids at a point in time for each of the divs and matching dialog open-scripts. Keep in mind, I removed the preg replace function since it kind of complicates the problem. If anyone has any ideas, they will be greatly appreciated. <?php $id=uniqid(); $id2=uniqid(); echo "<div id=\"$id2\"> </div>"; ?> $.ui.dialog.defaults.bgiframe = true; $(function() { $("<?php echo"#$id2"; ?>").dialog({hide: 'clip', modal: true ,width: 600,height: 350,position: 'center', show: 'clip',stack: true,title: 'title', minHeight: 25, minWidth: 100, autoOpen: false}); $('<?php echo"#$id"; ?>').click(function() { $('<?php echo"#$id2"; ?>').dialog('open'); }) .hover( function(){ $(this).addClass("ui-state-hover"); }, function(){ $(this).removeClass("ui-state-hover"); } ).mousedown(function(){ $(this).addClass("ui-state-active"); }) .mouseup(function(){ $(this).removeClass("ui-state-active"); }); });

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• Can I make TCP/IP session to run less than 60 seconds?

  - by Pavel

  Our server is overloaded with TCP/IP sessions, we have 1200 - 1500 of them. Most of them are hanging in TIME_OUT state. It turns out that a connection in TIME_OUT state occupies a socket until 60 second time-out is elapsed. The problem is that the server gets unresponsive and many clients are not getting served. I have made a simple test: download an XML file from the server with Internet Explorer 8.0 The download finishes in a fraction of second. But then I see that the TCP/IP connection is hanging in TIME_OUT state for 60 seconds. Is there any way to get rid of TIME_OUT waiting or make it less to free the socket for new connections? I understand why TCP/IP connection enters TIME_OUT state, but I don't understand why Internet Explorer does not close the connection after the XML file download is over. The details. Our server runs web service written in Perl (mod-perl). The service provides weather data to clients. Client is a Flash appication (actually Flash ActiveX control embedded in Windows application). Apache "Keep Alive" option is set to 0

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• Running a Model::find in for loop in cakephp v1.3

  - by Gaurav Sharma

  Hi all, How can I achieve the following result in cakephp: In my application a Topic is related to category, category is related to city and city is finally related to state in other words: topic belongs to category, category belongs to city , city belongs to state.. Now in the Topic controller's index action I want to find out all the topics and it's city and state. How can I do this. I can easily do this using a custom query ($this-Model-query() function ) but then I will be facing pagination difficulties. I tried doing like this function index() { $this->Topic->recursive = 0; $topics = $this->paginate(); for($i=0; $i<count($topics);$i++) { $topics[$i]['City'] = $this->Topic->Category->City->find('all', array('conditions' => array('City.id' => $topics[$i]['Category']['city_id']))); } $this->set(compact('messages')); } The method that I have adopted is not a good one (running query in a loop) Using the recursive property and setting it to highest value (2) will degrade performance and is not going to yield me state information. How shall I solve this ? Please help Thanks

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• angular bootstrap typeahead bug

  - by Mohammad Akbari

  i use angular bootstrap typeahead (this lib ui-bootstrap-tpls.js ) in my app, when use two typeahead in one scope, only one work well, and other not work, this is my code angular.module('plunker', ['ui.bootstrap']); function TypeaheadCtrl($scope) { $scope.selected = undefined; $scope.selected2 = undefined; $scope.states = ['Alabama', 'Alaska','California', 'Hawaii', 'Wisconsin', 'Wyoming']; } <html ng-app="plunker"> <head> <title></title> <link href="lib/angular-bootstrap/bootstrap.css" rel="stylesheet" /> <script src="lib/angular/angular.js"></script> <script src="lib/angular-bootstrap/ui-bootstrap-tpls-0.3.0.min.js"></script> <script src="app.js"></script> </head> <body> <div class='container-fluid' ng-controller="TypeaheadCtrl"> <pre>Model: {{selected| json}}</pre> <input type="text" ng-model="selected" typeahead="state for state in states | filter:$viewValue"> <input type="text" ng-model="selected2" typeahead="state for state in states | filter:$viewValue"> </div> </body> please check this and help.

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• Is this a good starting point for iptables in Linux?

  - by sbrattla

  Hi, I'm new to iptables, and i've been trying to put together a firewall which purpose is to protect a web server. The below rules are the ones i've put together so far, and i would like to hear if the rules makes sense - and wether i've left out anything essential? In addition to port 80, i also need to have port 3306 (mysql) and 22 (ssh) open for external connections. Any feedback is highly appreciated! #!/bin/sh # Clear all existing rules. iptables -F # ACCEPT connections for loopback network connection, 127.0.0.1. iptables -A INPUT -i lo -j ACCEPT # ALLOW established traffic iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # DROP packets that are NEW but does not have the SYN but set. iptables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP # DROP fragmented packets, as there is no way to tell the source and destination ports of such a packet. iptables -A INPUT -f -j DROP # DROP packets with all tcp flags set (XMAS packets). iptables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP # DROP packets with no tcp flags set (NULL packets). iptables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP # ALLOW ssh traffic (and prevent against DoS attacks) iptables -A INPUT -p tcp --dport ssh -m limit --limit 1/s -j ACCEPT # ALLOW http traffic (and prevent against DoS attacks) iptables -A INPUT -p tcp --dport http -m limit --limit 5/s -j ACCEPT # ALLOW mysql traffic (and prevent against DoS attacks) iptables -A INPUT -p tcp --dport mysql -m limit --limit 25/s -j ACCEPT # DROP any other traffic. iptables -A INPUT -j DROP

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• How to use ID selector after jQuery html()

  - by user555617

  It's amazing to try to understand why the function alert("hello") is not generated after clicking more than once... There is some method to do this function is executed? Note that doesn't work after update using html() involving id "press" in button. Any idea? See: http://jsbin.com/atuqu3 JavaScript: $(document).ready(function (){ $("#press").click(function() { $("#relation-states").html('<select id="state" name="state"> <option value="Texas">Texas</option> </select><button id="press" type="button" title="" aria-haspopup="true" style="width: 175px;"><span>Select an item</span></button>');; alert("hello"); }); }); HTML: <div id="relation-states"> <select id="state" name="state"> <option value="New York">New York</option> </select> <button id="press" type="button" title="" aria-haspopup="true" style="width: 175px;"><span>Select an item</span></button> </div>

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• How can get unique values from data table using dql?

  - by piemesons

  I am having a table in which there is a column in which various values are stored.i want to retrieve unique values from that table using dql. Doctrine_Query::create() ->select('rec.school') ->from('Records rec') ->where("rec.city='$city' ") ->execute(); Now i want only unique values. Can anybody tell me how to do that... Edit Table Structure: CREATE TABLE IF NOT EXISTS `records` ( `id` int(11) NOT NULL AUTO_INCREMENT, `state` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `city` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, `school` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=16334 ; This is the Query I am using: Doctrine_Query::create() ->select('DISTINCT rec.city') ->from('Records rec') ->where("rec.state = '$state'") // ->getSql(); ->execute(); Generting Sql for this gives me: SELECT DISTINCT r.id AS r__id, r.city AS r__city FROM records r WHERE r.state = 'AR' Now check the sql generated:::: DISTINCT is on 'id' column where as i want Distinct on city column. Anybody know how to fix this. EDIT2 Id is unique cause its an auto incremental value.Ya i have some real duplicates in city column like: Delhi and Delhi. Right.. Now when i am trying to fetch data from it, I am getting Delhi two times. How can i make query like this: select DISTINCT rec.city where state="xyz"; Cause this will give me the proper output. EDIT3: Anybody who can tell me how to figure out this query..???

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• Compromising design & code quality to integrate with existing modules

  - by filip-fku

  Greetings! I inherited a C#.NET application I have been extending and improving for a while now. Overall it was obviously a rush-job (or whoever wrote it was seemingly less competent than myself). The app pulls some data from an embedded device & displays and manipulates it. At the core is a communications thread in the main application form which executes a 600+ lines of code method which calls functions all over the place, implementing a state machine - lots of if-state-then-do type code. Interaction with the device is done by setting the state/mode globally and letting the thread do it's thing. (This is just one example of the badness of the code - overall it is not very OO-like, it reminds of the style of embedded C code the device firmware is written in). My problem is that this piece of code is central to the application. The software, communications protocol or device firmware are not documented at all. Obviously to carry on with my work I have to interact with this code. What I would like some guidance on, is whether it is worth scrapping this code & trying to piece together something more reasonable from the information I can reverse engineer? I can't decide! The reason I don't want to refactor is because the code already works, and changing it will surely be a long, laborious and unpleasant task. On the flip side, not refactoring means I have to sometimes compromise the design of other modules so that I may call my code from this state machine! I've heard of "If it ain't broke don't fix it!", so I am wondering if it should apply when "it" is influencing the design of future code! Any advice would be appreciated! Thanks!

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• XSLT special characters

  - by Apurv

  In the following XSL transformation how do I output the '<' and '' symbol? Input XML: <TestResult bugnumber="3214" testname="display.methods::close->test_ManyInvoke" errortype="Failure"><ErrorMessage><![CDATA[calling close() method failed - expected:<2>]]></ErrorMessage> XSLT: <xsl:template match="TestResult"> <xsl:variable name="errorMessage"> <xsl:value-of select="ErrorMessage" disable-output-escaping="yes"/> </xsl:variable> <Test name='{@testname}'> <TestResult> <Passed>false</Passed> <State>failure</State> <Metadata> <Entry name='bugnumber' value='{@bugnumber}' /> </Metadata> <TestOutput> <Metadata> <Entry name='ErrorMessage' value='{$errorMessage}' /> </Metadata> </TestOutput> </TestResult> </Test> </xsl:template> Output XML: <Test name="display.methods::close-&gttest_ManyInvoke"> <TestResult> <Passed>false</Passed> <State>failure</State> <Metadata> <Entry name="bugnumber" value="3214"/> </Metadata> <TestOutput> <Metadata> <Entry name="ErrorMessage" value="calling close() method failed - expected:&lt;2&gt;"/> </Metadata> </TestOutput> </TestResult> </Test>

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• Event Source Live streaming in Ruby on rails onError method

  - by kishorebjv

  I'm trying to implement basic rails4 code with eventsource API & Action controller live, Everything is fine but I'm not able to reach event listner . Controller code: class HomeController < ApplicationController include ActionController::Live def tester response.headers["Content-Type"] = "text/event-stream" 3.times do |n| response.stream.write "message: hellow world! \n\n" sleep 2 end end Js code: var evSource = new EventSource("/home/tester"); evSource.onopen = function (e) { console.log("OPEN state \n"+e.data); }; evSource.addEventListener('message',function(e){ console.log("EventListener .. code.."); },false); evSource.onerror = function (e) { console.log("Error State \n\n"+e.data); }; & When i reloading the page, My console output was "OPEN state" & then "Error State" as output.. event-listener code was not displaying . 1.When I'm curling the page, "message: Hellow world!" was displaying. 2.I changed in development.rb config.cache_classes = true config.eager_load = true 3. My browsers are chrome & firefox are latest versions, so no issues with them, Where I'm missing? suggestions please!

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• Object inside of array -- works in one scope but not in another?

  - by Earlz

  Ok I've been learning some of the more advanced aspects of Javascript and now trying to use this I'm stuck. Here is my code: function Data(){} function init(state){ var item; item=new Data(); item.fieldrid=17; item.description='foo'; state.push(item); }; function findInState(state,fieldrid) { for (var item in state) { alert(item.fieldrid); //prints undefined if (item.fieldrid == fieldrid) { return item; } } return null; } var s=[]; init(s); alert(s[0].fieldrid); //prints 17 (expected) alert(findInState(s,17).fieldrid); //exception here. function returns null. A running example is here at jsbin Why does this not work? I would expect the alert in findInState to yield 17 but instead it yields undefined. What am I doing wrong?

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• How to update attributes without valitation

  - by Brian Roisentul

  I've got a model with its validations, and I found out that I can't update an attribute without validating the object before. I already tried to add on => :create syntax at the end of each validation line, but I got the same results. My announcement model have the following validations: validates_presence_of :title validates_presence_of :description validates_presence_of :announcement_type_id validate :validates_publication_date validate :validates_start_date validate :validates_start_end_dates validate :validates_category validate :validates_province validates_length_of :title, :in => 6..255, :on => :save validates_length_of :subtitle, :in => 0..255, :on => :save validates_length_of :subtitle, :in => 0..255, :on => :save validates_length_of :place, :in => 0..50, :on => :save validates_numericality_of :vacants, :greater_than_or_equal_to => 0, :only_integer => true validates_numericality_of :price, :greater_than_or_equal_to => 0, :only_integer => true My rake task does the following: task :announcements_expiration => :environment do announcements = Announcement.expired announcements.each do |a| #Gets the user that owns the announcement user = User.find(a.user_id) puts a.title + '...' a.state = 'deactivated' if a.update_attributes(:state => a.state) puts 'state changed to deactivated' else a.errors.each do |e| puts e end end end This throws all the validation exceptions for that model, in the output. Does anybody how to update an attribute without validating the model?

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• How to reset the context to the original rectangle after clipping it for drawing?

  - by mystify

  I try to draw a sequence of pattern images (different repeated patterns in one view). So what I did is this, in a loop: CGContextRef context = UIGraphicsGetCurrentContext(); // clip to the drawing rectangle to draw the pattern for this portion of the view CGContextClipToRect(context, drawingRect); // the first call here works fine... but for the next nothing will be drawn CGContextDrawTiledImage(context, CGRectMake(0, 0, 2, 31), [img CGImage]); I think that after I've clipped the context to draw the pattern in the specific rectangle, I cut out a snippet from the big canvas and the next time, my canvas is gone. can't cut out another snippet. So I must reset that clipping somehow in order to be able to draw another pattern again somewhere else? Edit: In the documentation I found this: CGContextClip: "... Therefore, to re-enlarge the paintable area by restoring the clipping path to a prior state, you must save the graphics state before you clip and restore the graphics state after you’ve completed any clipped drawing. ..." Well then, how to store the graphics state before clipping and how to restore it?

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• CakePHP - recursive on specific fields in model?

  - by Paul

  Hi, I'm pretty new to CakePHP but I think I'm starting to get the hang of it. I'm trying to pull related table information recursively, but I want to specify which related models to recurse on. Let me give you an example to demonstrate my goal: I have a model "Customer", which has info like Company name, website, etc. "Customer" hasMany "Addresses", which contain info for individual contacts like Contact Name, Street, City, State, Country, etc. "Customer" also belongsTo "CustomerType", which is just has descriptive category info - a name and description, like "Distributor" or "Manufacturer". When I do a find on "Customer" I want to get associated "CustomerType" and "Address" info as sub-arrays, and this works fine just by setting up the hasMany and belongsTo associations properly. But now, here's my issue: I want to get associated State/Country info. So, instead of each "Address" array row just having "state_id", I want it to have "state" = array("id" = 20, "name" = "New York",...) etc. If I set $recursive to a higher value (e.g., 2) in the Partner model, I get what I want for the State/Country info in each "Address". BUT it also recurses on "CustomerType", and that results in the "CustomerType" field of my "Partner" object having a huge array of all Customer objects that match that type, which could be thousands long. So the point is, I DON'T want to recurse on "CustomerType", only on "Address". Is there a way I can set this up? Sorry for the long-winded question, and thanks in advance!

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• How to update attributes without validation

  - by Brian Roisentul

  I've got a model with its validations, and I found out that I can't update an attribute without validating the object before. I already tried to add on => :create syntax at the end of each validation line, but I got the same results. My announcement model have the following validations: validates_presence_of :title validates_presence_of :description validates_presence_of :announcement_type_id validate :validates_publication_date validate :validates_start_date validate :validates_start_end_dates validate :validates_category validate :validates_province validates_length_of :title, :in => 6..255, :on => :save validates_length_of :subtitle, :in => 0..255, :on => :save validates_length_of :subtitle, :in => 0..255, :on => :save validates_length_of :place, :in => 0..50, :on => :save validates_numericality_of :vacants, :greater_than_or_equal_to => 0, :only_integer => true validates_numericality_of :price, :greater_than_or_equal_to => 0, :only_integer => true My rake task does the following: task :announcements_expiration => :environment do announcements = Announcement.expired announcements.each do |a| #Gets the user that owns the announcement user = User.find(a.user_id) puts a.title + '...' a.state = 'deactivated' if a.update_attributes(:state => a.state) puts 'state changed to deactivated' else a.errors.each do |e| puts e end end end This throws all the validation exceptions for that model, in the output. Does anybody how to update an attribute without validating the model?

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• :include and table aliasing

  - by dondo

  I'm suffering from a variant of the problem described here: ActiveRecord assigns table aliases for association joins fairly unpredictably. The first association to a given table keeps the table name. Further joins with associations to that table use aliases including the association names in the path... but it is common for app developers not to know about [other] joins at coding time. In my case I'm being bitten by a toxic mix of has_many and :include. Many tables in my schema have a state column, and the has_many wants to specify conditions on that column: has_many :foo, :conditions => {:state => 1}. However, since the state column appears in many tables, I disambiguate by explicitly specifying the table name: has_many :foo, :conditions => "this_table.state = 1". This has worked fine until now, when for efficiency I want to add an :include to preload a fairly deep tree of data. This causes the table to be aliased inconsistently in different code paths. My reading of the tickets referenced above is that this problem is not and will not be fixed in Rails 2.x. However, I don't see any way to apply the suggested workaround (to specify the aliased table name explicitly in the query). I'm happy to specify the table alias explicitly in the has_many statement, but I don't see any way to do so. As such, the workaround doesn't appear applicable to this situation (nor, I presume, in many 'named_scope' scenarios). Is there a viable workaround?

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• Quick question regarding MVC framework for a java game

  - by Jason

  I have a question regarding the use of the MVC framework for a blackjack game im writing in java. As I understand, my model would be a class that stores the state of the game, and more specifically, each players hand. Within the model class, I would have an array of listeners, which would be notified each time the game state changes (ie a player has drawn a new card). These listeners would be my viewer, which is the class that handles the display of the game. This class would implement the ActionListener interface, and each time the model changes, it would call/"notify" my viewer's actionPerformed method. My question is as follows: I intend to have two JPanels, each devoted to displaying the respective player's hand. As a player draws a new card, a new ImageIcon would be added to the panel. My question is how would the viewer class know what card has been added to the player's hand? I suppose I could store the player's hand before a notify event, and then upon the notification event, compare the new state with the old, to find out what has changed. I'm a complete novice here, so I could be completely wrong, but it seems a bit tedious to do this. Is there a more efficient/common way of detecting what has changed in the model between the before and after state? Another solution would be to redraw the entire panel each time the notification occurs? Would this be a better idea?

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• C# form - checkboxes do not respond to plus/minus keys - easy workaround?

  - by Scott

  On forms created with pre dotNET VB and C++ (MFC), a checkbox control responded to the plus/minus key without custom programming. When focus was on the checbox control, pressing PLUS would check the box, no matter what the previous state (checked/unchecked), while pressing MINUS would uncheck it, no matter the previous state. C# winform checkboxes do not seem to exhibit this behavior. Said behavior was very, very handy for automation, whereby the automating program would set focus to a checkbox control and issue a PLUS or MINUS to check or uncheck it. Without this capability, that cannot be done, as the automation program (at least the one I am using) is unable to query the current state of the checkbox (so it can decide whether to issue a SPACE key to toggle the state to the desired one). I've gone over the properties of a checkbox in the Visual Studio 2008 IDE and could not find anything that would restore/enable response to PLUS/MINUS. Since I am in control of the sourcecode for the WinForms in question, I could replace all checkbox controls with a custom checkbox control, but blech, I'd like to avoid that - heck, I don't think I could even consider that given the amount of refactoring that would need to be done. So the bottom line is: does anyone know of a way to get this behavior back more easily than a coding change?

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• Parallelism in .NET – Part 14, The Different Forms of Task

  - by Reed

  Before discussing Task creation and actual usage in concurrent environments, I will briefly expand upon my introduction of the Task class and provide a short explanation of the distinct forms of Task.  The Task Parallel Library includes four distinct, though related, variations on the Task class. In my introduction to the Task class, I focused on the most basic version of Task.  This version of Task, the standard Task class, is most often used with an Action delegate.  This allows you to implement for each task within the task decomposition as a single delegate. Typically, when using the new threading constructs in .NET 4 and the Task Parallel Library, we use lambda expressions to define anonymous methods.  The advantage of using a lambda expression is that it allows the Action delegate to directly use variables in the calling scope.  This eliminates the need to make separate Task classes for Action<T>, Action<T1,T2>, and all of the other Action<…> delegate types.  As an example, suppose we wanted to make a Task to handle the ”Show Splash” task from our earlier decomposition.  Even if this task required parameters, such as a message to display, we could still use an Action delegate specified via a lambda: // Store this as a local variable string messageForSplashScreen = GetSplashScreenMessage(); // Create our task Task showSplashTask = new Task( () => { // We can use variables in our outer scope, // as well as methods scoped to our class! this.DisplaySplashScreen(messageForSplashScreen); }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This provides a huge amount of flexibility.  We can use this single form of task for any task which performs an operation, provided the only information we need to track is whether the task has completed successfully or not.  This leads to my first observation: Use a Task with a System.Action delegate for any task for which no result is generated. This observation leads to an obvious corollary: we also need a way to define a task which generates a result.  The Task Parallel Library provides this via the Task<TResult> class. Task<TResult> subclasses the standard Task class, providing one additional feature – the ability to return a value back to the user of the task.  This is done by switching from providing an Action delegate to providing a Func<TResult> delegate.  If we decompose our problem, and we realize we have one task where its result is required by a future operation, this can be handled via Task<TResult>.  For example, suppose we want to make a task for our “Check for Update” task, we could do: Task<bool> checkForUpdateTask = new Task<bool>( () => { return this.CheckWebsiteForUpdate(); }); Later, we would start this task, and perform some other work.  At any point in the future, we could get the value from the Task<TResult>.Result property, which will cause our thread to block until the task has finished processing: // This uses Task<bool> checkForUpdateTask generated above... // Start the task, typically on a background thread checkForUpdateTask.Start(); // Do some other work on our current thread this.DoSomeWork(); // Discover, from our background task, whether an update is available // This will block until our task completes bool updateAvailable = checkForUpdateTask.Result; This leads me to my second observation: Use a Task<TResult> with a System.Func<TResult> delegate for any task which generates a result. Task and Task<TResult> provide a much cleaner alternative to the previous Asynchronous Programming design patterns in the .NET framework.  Instead of trying to implement IAsyncResult, and providing BeginXXX() and EndXXX() methods, implementing an asynchronous programming API can be as simple as creating a method that returns a Task or Task<TResult>.  The client side of the pattern also is dramatically simplified – the client can call a method, then either choose to call task.Wait() or use task.Result when it needs to wait for the operation’s completion. While this provides a much cleaner model for future APIs, there is quite a bit of infrastructure built around the current Asynchronous Programming design patterns.  In order to provide a model to work with existing APIs, two other forms of Task exist.  There is a constructor for Task which takes an Action<Object> and a state parameter.  In addition, there is a constructor for creating a Task<TResult> which takes a Func<Object, TResult> as well as a state parameter.  When using these constructors, the state parameter is stored in the Task.AsyncState property. While these two overloads exist, and are usable directly, I strongly recommend avoiding this for new development.  The two forms of Task which take an object state parameter exist primarily for interoperability with traditional .NET Asynchronous Programming methodologies.  Using lambda expressions to capture variables from the scope of the creator is a much cleaner approach than using the untyped state parameters, since lambda expressions provide full type safety without introducing new variables.

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• [OT] : Windows Activation, en masse

  - by AaronBertrand

  This weekend I discovered a minor issue in one of my virtual environments. I had built out 100 VMs based on a Hyper-V template, but I forgot to activate the original source before creating the template, so all of the machines were suddenly out of compliance. While easy enough on a one- or two-machine basis to just log into the machine and activate manually, there was no way I was even going to dream of repeating that process on 100 machines. My First Reaction : PowerShell Whenever I do anything with...(read more)

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• Session memory – who’s this guy named Max and what’s he doing with my memory?

  - by extended_events

  SQL Server MVP Jonathan Kehayias (blog) emailed me a question last week when he noticed that the total memory used by the buffers for an event session was larger than the value he specified for the MAX_MEMORY option in the CREATE EVENT SESSION DDL. The answer here seems like an excellent subject for me to kick-off my new “401 – Internals” tag that identifies posts where I pull back the curtains a bit and let you peek into what’s going on inside the extended events engine. In a previous post (Option Trading: Getting the most out of the event session options) I explained that we use a set of buffers to store the event data before  we write the event data to asynchronous targets. The MAX_MEMORY along with the MEMORY_PARTITION_MODE defines how big each buffer will be. Theoretically, that means that I can predict the size of each buffer using the following formula: max memory / # of buffers = buffer size If it was that simple I wouldn’t be writing this post. I’ll take “boundary” for 64K Alex For a number of reasons that are beyond the scope of this blog, we create event buffers in 64K chunks. The result of this is that the buffer size indicated by the formula above is rounded up to the next 64K boundary and that is the size used to create the buffers. If you think visually, this means that the graph of your max_memory option compared to the actual buffer size that results will look like a set of stairs rather than a smooth line. You can see this behavior by looking at the output of dm_xe_sessions, specifically the fields related to the buffer sizes, over a range of different memory inputs: Note: This test was run on a 2 core machine using per_cpu partitioning which results in 5 buffers. (Seem my previous post referenced above for the math behind buffer count.) input_memory_kb total_regular_buffers regular_buffer_size total_buffer_size 637 5 130867 654335 638 5 130867 654335 639 5 130867 654335 640 5 196403 982015 641 5 196403 982015 642 5 196403 982015 This is just a segment of the results that shows one of the “jumps” between the buffer boundary at 639 KB and 640 KB. You can verify the size boundary by doing the math on the regular_buffer_size field, which is returned in bytes: 196403 – 130867 = 65536 bytes 65536 / 1024 = 64 KB The relationship between the input for max_memory and when the regular_buffer_size is going to jump from one 64K boundary to the next is going to change based on the number of buffers being created. The number of buffers is dependent on the partition mode you choose. If you choose any partition mode other than NONE, the number of buffers will depend on your hardware configuration. (Again, see the earlier post referenced above.) With the default partition mode of none, you always get three buffers, regardless of machine configuration, so I generated a “range table” for max_memory settings between 1 KB and 4096 KB as an example. start_memory_range_kb end_memory_range_kb total_regular_buffers regular_buffer_size total_buffer_size 1 191 NULL NULL NULL 192 383 3 130867 392601 384 575 3 196403 589209 576 767 3 261939 785817 768 959 3 327475 982425 960 1151 3 393011 1179033 1152 1343 3 458547 1375641 1344 1535 3 524083 1572249 1536 1727 3 589619 1768857 1728 1919 3 655155 1965465 1920 2111 3 720691 2162073 2112 2303 3 786227 2358681 2304 2495 3 851763 2555289 2496 2687 3 917299 2751897 2688 2879 3 982835 2948505 2880 3071 3 1048371 3145113 3072 3263 3 1113907 3341721 3264 3455 3 1179443 3538329 3456 3647 3 1244979 3734937 3648 3839 3 1310515 3931545 3840 4031 3 1376051 4128153 4032 4096 3 1441587 4324761 As you can see, there are 21 “steps” within this range and max_memory values below 192 KB fall below the 64K per buffer limit so they generate an error when you attempt to specify them. Max approximates True as memory approaches 64K The upshot of this is that the max_memory option does not imply a contract for the maximum memory that will be used for the session buffers (Those of you who read Take it to the Max (and beyond) know that max_memory is really only referring to the event session buffer memory.) but is more of an estimate of total buffer size to the nearest higher multiple of 64K times the number of buffers you have. The maximum delta between your initial max_memory setting and the true total buffer size occurs right after you break through a 64K boundary, for example if you set max_memory = 576 KB (see the green line in the table), your actual buffer size will be closer to 767 KB in a non-partitioned event session. You get “stepped up” for every 191 KB block of initial max_memory which isn’t likely to cause a problem for most machines. Things get more interesting when you consider a partitioned event session on a computer that has a large number of logical CPUs or NUMA nodes. Since each buffer gets “stepped up” when you break a boundary, the delta can get much larger because it’s multiplied by the number of buffers. For example, a machine with 64 logical CPUs will have 160 buffers using per_cpu partitioning or if you have 8 NUMA nodes configured on that machine you would have 24 buffers when using per_node. If you’ve just broken through a 64K boundary and get “stepped up” to the next buffer size you’ll end up with total buffer size approximately 10240 KB and 1536 KB respectively (64K * # of buffers) larger than max_memory value you might think you’re getting. Using per_cpu partitioning on large machine has the most impact because of the large number of buffers created. If the amount of memory being used by your system within these ranges is important to you then this is something worth paying attention to and considering when you configure your event sessions. The DMV dm_xe_sessions is the tool to use to identify the exact buffer size for your sessions. In addition to the regular buffers (read: event session buffers) you’ll also see the details for large buffers if you have configured MAX_EVENT_SIZE. The “buffer steps” for any given hardware configuration should be static within each partition mode so if you want to have a handy reference available when you configure your event sessions you can use the following code to generate a range table similar to the one above that is applicable for your specific machine and chosen partition mode. DECLARE @buf_size_output table (input_memory_kb bigint, total_regular_buffers bigint, regular_buffer_size bigint, total_buffer_size bigint) DECLARE @buf_size int, @part_mode varchar(8) SET @buf_size = 1 -- Set to the begining of your max_memory range (KB) SET @part_mode = 'per_cpu' -- Set to the partition mode for the table you want to generate WHILE @buf_size <= 4096 -- Set to the end of your max_memory range (KB) BEGIN     BEGIN TRY         IF EXISTS (SELECT * from sys.server_event_sessions WHERE name = 'buffer_size_test')             DROP EVENT SESSION buffer_size_test ON SERVER         DECLARE @session nvarchar(max)         SET @session = 'create event session buffer_size_test on server                         add event sql_statement_completed                         add target ring_buffer                         with (max_memory = ' + CAST(@buf_size as nvarchar(4)) + ' KB, memory_partition_mode = ' + @part_mode + ')'         EXEC sp_executesql @session         SET @session = 'alter event session buffer_size_test on server                         state = start'         EXEC sp_executesql @session         INSERT @buf_size_output (input_memory_kb, total_regular_buffers, regular_buffer_size, total_buffer_size)             SELECT @buf_size, total_regular_buffers, regular_buffer_size, total_buffer_size FROM sys.dm_xe_sessions WHERE name = 'buffer_size_test'     END TRY     BEGIN CATCH         INSERT @buf_size_output (input_memory_kb)             SELECT @buf_size     END CATCH     SET @buf_size = @buf_size + 1 END DROP EVENT SESSION buffer_size_test ON SERVER SELECT MIN(input_memory_kb) start_memory_range_kb, MAX(input_memory_kb) end_memory_range_kb, total_regular_buffers, regular_buffer_size, total_buffer_size from @buf_size_output group by total_regular_buffers, regular_buffer_size, total_buffer_size Thanks to Jonathan for an interesting question and a chance to explore some of the details of Extended Event internals. - Mike

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• How can Google publish Dalvik as Java-language compatible since Java is a trademark?

  - by Bruno Chagas

  According to this thread Java and JVM license You can write a compiler that implements the Java Language Specification or write a JVM that implements the Java Virtual Machine specification, but when you officially want to call it "Java", you have to prove it is compatible by passing the tests of the TCK (technology compatibility kit) and pay for a license from Oracle. So, how can Google (or any other java implementation for that matter) claims that Dalvik is a Java virtual machine?

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• Don’t install JDev and BPM in the same Home

  - by Mark Nelson

  I don’t think this is actually documented anywhere, but it is something that you will want to be aware of if you are using the BPM 11.1.1.5 Feature Pack. It is not supported to install the Feature Pack patch into an Oracle Home which contains JDeveloper and the runtime components (WebLogic, SOA, BPM, etc.) If you are installing on the same machine, like a developer’s machine for example, you should install JDeveloper into a separate Oracle (Middleware) Home.

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• Is Python Interpreted or Compiled?

  - by crodjer

  This is just a wondering I had while reading about interpreted and compiled languages. Ruby is no doubt an interpreted language, since source code is compiled by an interpreter at the point of execution. On the contrary C is a compiled language, as one have to compile the source code first according to the machine and then execute. This results is much faster execution. Now coming to Python: A python code (somefile.py) when imported creates a file (somefile.pyc) in the same directory. Let us say the import is done in a python shell or django module. After the import I change the code a bit and execute the imported functions again to find that it is still running the old code. This suggests that *.pyc files are compiled python files similar to executable created after compilation of a C file, though I can't execute *.pyc file directly. When the python file (somefile.py) is executed directly ( ./somefile.py or python somefile.py ) no .pyc file is created and the code is executed as is indicating interpreted behavior. These suggest that a python code is compiled every time it is imported in a new process to crate a .pyc while it is interpreted when directly executed. So which type of language should I consider it as? Interpreted or Compiled? And how does its efficiency compare to interpreted and compiled languages? According to wiki's Interpreted Languages page it is listed as a language compiled to Virtual Machine Code, what is meant by that? Update Looking at the answers it seems that there cannot be a perfect answer to my questions. Languages are not only interpreted or only compiled, but there is a spectrum of possibilities between interpreting and compiling. From the answers by aufather, mipadi, Lenny222, ykombinator, comments and wiki I found out that in python's major implementations it is compiled to bytecode, which is a highly compressed and optimized representation and is machine code for a virtual machine, which is implemented not in hardware, but in the bytecode interpreter. Also the the languages are not interpreted or compiled, but rather language implementations either interpret or compile code. I also found out about Just in time compilation As far as execution speed is concerned the various benchmarks cannot be perfect and depend on context and the task which is being performed. Please tell if I am wrong in my interpretations.

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• Gnome Do not Launching

  - by PyRulez

  When I try running gnome do, I get this. chris@Chris-Ubuntu-Laptop:~$ gnome-do pgrep: invalid user name: -u and it is not writable Trying sudo: chris@Chris-Ubuntu-Laptop:~$ sudo gnome-do [NetworkService] Could not initialize Network Manager dbus: Unable to open the session message bus. [Error 17:54:30.122] [SystemService] Could not initialize dbus: Unable to open the session message bus. (Do:2401): Wnck-CRITICAL **: wnck_set_client_type got called multiple times. (Do:2401): libdo-WARNING **: Binding '<Super>space' failed! [Error 17:54:30.649] [AbstractKeyBindingService] Key "" is already mapped. Tomboy.NotesItemSource "Tomboy Notes" encountered an error in UpdateItems: System.TypeInitializationException: An exception was thrown by the type initializer for Tomboy.TomboyDBus ---> System.Exception: Unable to open the session message bus. ---> System.ArgumentNullException: Argument cannot be null. Parameter name: address at NDesk.DBus.Bus.Open (System.String address) [0x00000] in <filename unknown>:0 at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 at Tomboy.TomboyDBus..cctor () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at Tomboy.NotesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Firefox.PlacesItemSource "Firefox Places" encountered an error in UpdateItems: System.InvalidCastException: Cannot cast from source type to destination type. at Mono.Data.Sqlite.SqliteDataReader.VerifyType (Int32 i, DbType typ) [0x00000] in <filename unknown>:0 at Mono.Data.Sqlite.SqliteDataReader.GetString (Int32 i) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource+<LoadPlaceItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem].AddEnumerable (IEnumerable`1 enumerable) [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem]..ctor (IEnumerable`1 collection) [0x00000] in <filename unknown>:0 at System.Linq.Enumerable.ToArray[PlaceItem] (IEnumerable`1 source) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Do.Universe.Linux.GNOMESpecialLocationsItemSource "GNOME Special Locations" encountered an error in UpdateItems: System.IO.FileNotFoundException: Could not find file "/root/.gtk-bookmarks". File name: '/root/.gtk-bookmarks' at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0 at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare) at System.IO.File.OpenRead (System.String path) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path, System.Text.Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.StreamReader:.ctor (string) at Do.Universe.Linux.GNOMESpecialLocationsItemSource+<ReadBookmarkItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at Do.Universe.Linux.GNOMESpecialLocationsItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . ^[^\Full thread dump: "<unnamed thread>" tid=0x0xb7570700 this=0x0x56f18 thread handle 0x403 state : not waiting owns () at (wrapper managed-to-native) Mono.Unix.Native.Syscall.read (int,intptr,ulong) <0xffffffff> at Mono.Unix.Native.Syscall.read (int,void*,ulong) <0x00023> at Mono.Unix.UnixStream.Read (byte[],int,int) <0x0008b> at NDesk.DBus.Connection.ReadMessage () <0x0003c> at NDesk.DBus.Connection.Iterate () <0x0001b> at NDesk.DBus.BusG/<Init>c__AnonStorey0.<>m__0 (intptr,NDesk.GLib.IOCondition,intptr) <0x00033> at (wrapper native-to-managed) NDesk.DBus.BusG/<Init>c__AnonStorey0.<>m__0 (intptr,NDesk.GLib.IOCondition,intptr) <0xffffffff> at (wrapper managed-to-native) Gtk.Clipboard.gtk_clipboard_wait_is_text_available (intptr) <0xffffffff> at Gtk.Clipboard.WaitIsTextAvailable () <0x00017> at Do.Universe.SelectedTextItem.UpdateSelection (object,System.EventArgs) <0x00027> at Do.Platform.AbstractApplicationService.OnSummoned () <0x00025> at Do.Platform.ApplicationService.<ApplicationService>m__31 (object,System.EventArgs) <0x00013> at Do.Core.Controller.OnSummoned () <0x00025> at Do.Core.Controller.Summon () <0x00027> at Do.Do.Main (string[]) <0x001eb> at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <0xffffffff> "<unnamed thread>" tid=0x0xb2c81b40 this=0x0x194150 thread handle 0x412 state : interrupted state owns () at (wrapper managed-to-native) System.IO.InotifyWatcher.ReadFromFD (intptr,byte[],intptr) <0xffffffff> at System.IO.InotifyWatcher.Monitor () <0x0005f> at System.Threading.Thread.StartInternal () <0x00057> at (wrapper runtime-invoke) object.runtime_invoke_void__this__ (object,intptr,intptr,intptr) <0xffffffff> "Universe Update Dispatcher" tid=0x0xb29ffb40 this=0x0x569d8 thread handle 0x41b state : interrupted state owns () at (wrapper managed-to-native) System.Threading.WaitHandle.WaitOne_internal (System.Threading.WaitHandle,intptr,int,bool) <0xffffffff> at System.Threading.WaitHandle.WaitOne (System.TimeSpan,bool) <0x00133> at System.Threading.WaitHandle.WaitOne (System.TimeSpan) <0x00022> at Do.Core.UniverseManager.UniverseUpdateLoop () <0x0007a> at System.Threading.Thread.StartInternal () <0x00057> at (wrapper runtime-invoke) object.runtime_invoke_void__this__ (object,intptr,intptr,intptr) <0xffffffff> Tomboy.NotesItemSource "Tomboy Notes" encountered an error in UpdateItems: System.TypeInitializationException: An exception was thrown by the type initializer for Tomboy.TomboyDBus ---> System.Exception: Unable to open the session message bus. ---> System.ArgumentNullException: Argument cannot be null. Parameter name: address at NDesk.DBus.Bus.Open (System.String address) [0x00000] in <filename unknown>:0 at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 at Tomboy.TomboyDBus..cctor () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at Tomboy.NotesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Firefox.PlacesItemSource "Firefox Places" encountered an error in UpdateItems: System.InvalidCastException: Cannot cast from source type to destination type. at Mono.Data.Sqlite.SqliteDataReader.VerifyType (Int32 i, DbType typ) [0x00000] in <filename unknown>:0 at Mono.Data.Sqlite.SqliteDataReader.GetString (Int32 i) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource+<LoadPlaceItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem].AddEnumerable (IEnumerable`1 enumerable) [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem]..ctor (IEnumerable`1 collection) [0x00000] in <filename unknown>:0 at System.Linq.Enumerable.ToArray[PlaceItem] (IEnumerable`1 source) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Do.Universe.Linux.GNOMESpecialLocationsItemSource "GNOME Special Locations" encountered an error in UpdateItems: System.IO.FileNotFoundException: Could not find file "/root/.gtk-bookmarks". File name: '/root/.gtk-bookmarks' at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0 at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare) at System.IO.File.OpenRead (System.String path) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path, System.Text.Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.StreamReader:.ctor (string) at Do.Universe.Linux.GNOMESpecialLocationsItemSource+<ReadBookmarkItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at Do.Universe.Linux.GNOMESpecialLocationsItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . It stops when I try my key combination, ctrl-alt-. It does not pop up though.

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