Search Results

Search found 16914 results on 677 pages for 'single threaded'.

Page 556/677 | < Previous Page | 552 553 554 555 556 557 558 559 560 561 562 563  | Next Page >

  • Prevent default on a click within a JQuery tabs in Google Chrome.

    - by Sydney
    I would like to prevent the default behaviour of a click on a link. I tried the return false; also javascript:void(0); in the href attribute but it doesn’t seem to work. It works fine in Firefox, but not in Chrome and IE. I have a single tab that loads via AJAX the content which is a simple link. <script type="text/javascript"> $(function() { $("#tabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); }, success: function() { alert('hello'); $('#lk').click(function() { alert('Click Me'); return false; }); } }, load: function(event, ui) { $('a', ui.panel).click(function() { $(ui.panel).load(this.href); return false; }); } }); }); </script> <body> <div id="tabs"> <ul> <li><a href="linkChild.htm">Link</a></li> </ul> </div> </body> The content of linkChild.htm is <a href="javascript:void(0)" id="lk">Click Me</a> So basically when the tab content is loaded with success, a click event is attached to the link “lk”. When I click on the link, the alert is displayed but then link disappears. I check the HTML and the element is actually removed from the DOM.

    Read the article

  • Deeply nested subqueries for traversing trees in MySQL

    - by nickf
    I have a table in my database where I store a tree structure using the hybrid Nested Set (MPTT) model (the one which has lft and rght values) and the Adjacency List model (storing parent_id on each node). my_table (id, parent_id, lft, rght, alias) This question doesn't relate to any of the MPTT aspects of the tree but I thought I'd leave it in in case anyone had a good idea about how to leverage that. I want to convert a path of aliases to a specific node. For example: "users.admins.nickf" would find the node with alias "nickf" which is a child of one with alias "admins" which is a child of "users" which is at the root. There is a unique index on (parent_id, alias). I started out by writing the function so it would split the path to its parts, then query the database one by one: SELECT `id` FROM `my_table` WHERE `parent_id` IS NULL AND `alias` = 'users';-- 1 SELECT `id` FROM `my_table` WHERE `parent_id` = 1 AND `alias` = 'admins'; -- 8 SELECT `id` FROM `my_table` WHERE `parent_id` = 8 AND `alias` = 'nickf'; -- 37 But then I realised I could do it with a single query, using a variable amount of nesting: SELECT `id` FROM `my_table` WHERE `parent_id` = ( SELECT `id` FROM `my_table` WHERE `parent_id` = ( SELECT `id` FROM `my_table` WHERE `parent_id` IS NULL AND `alias` = 'users' ) AND `alias` = 'admins' ) AND `alias` = 'nickf'; Since the number of sub-queries is dependent on the number of steps in the path, am I going to run into issues with having too many subqueries? (If there even is such a thing) Are there any better/smarter ways to perform this query?

    Read the article

  • Prototypal inheritance should save memory, right?

    - by Techpriester
    Hi Folks, I've been wondering: Using prototypes in JavaScript should be more memory efficient than attaching every member of an object directly to it for the following reasons: The prototype is just one single object. The instances hold only references to their prototype. Versus: Every instance holds a copy of all the members and methods that are defined by the constructor. I started a little experiment with this: var TestObjectFat = function() { this.number = 42; this.text = randomString(1000); } var TestObjectThin = function() { this.number = 42; } TestObjectThin.prototype.text = randomString(1000); randomString(x) just produces a, well, random String of length x. I then instantiated the objects in large quantities like this: var arr = new Array(); for (var i = 0; i < 1000; i++) { arr.push(new TestObjectFat()); // or new TestObjectThin() } ... and checked the memory usage of the browser process (Google Chrome). I know, that's not very exact... However, in both cases the memory usage went up significantly as expected (about 30MB for TestObjectFat), but the prototype variant used not much less memory (about 26MB for TestObjectThin). I also checked: The TestObjectThin instances contain the same string in their "text" property, so they are really using the property of the prototype. Now, I'm not so sure what to think about this. The prototyping doesn't seem to be the big memory saver at all. I know that prototyping is a great idea for many other reasons, but I'm specifically concerned with memory usage here. Any explanations why the prototype variant uses almost the same amount of memory? Am I missing something?

    Read the article

  • SQL using sum to count results of multiple subqueries

    - by asdas
    I have a table with 2 columns: integer and var char. I am given only the integer values but need to do work on the var char (string) values. Given an integer, and a list of other integers (no overlap), I want to find the string for that single integer. Then I want to take that string and do the INSTR command with that string, and all the other strings for all the other integers. Then I want the sum of all the INSTR so the result is one number. So lets say I have int x, and list y=[y0, y1, y2]. I want to do 3 INSTR commands like SUM(INSTR(string for x, string for y0), INSTR(string for x, string for y1), INSTR(string for x, string for y2)) I think im going in the wrong direction, this is what I have. Im not good with sub queries. SELECT SUM ( SELECT INSTR ( SELECT string FROM pages WHERE int=? LIMIT 1, ( SELECT string FROM pages WHERE id=? OR id=? OR id=? LIMIT 3 ) ) )

    Read the article

  • OPTICS Clustering algorithm. How to get the best epsilon

    - by Marco Galassi
    I am implementing a project which needs to cluster geographical points. OPTICS algorithm seems to be a very nice solution. It needs just 2 parameters as input(MinPts and Epsilon), which are, respectively, the minimum number of points needed to consider them as a cluster, and the distance value used to compare if two points are in can be placed in same cluster. My problem is that, due to the extreme variety of the points, I can't set a fixed epsilon. Just look at the image below. The same points structure but in a different scale would result very different. Suppose to set MinPts=2 and epsilon = 1Km. On the left, the algorithm would create 2 clusters(red and blue), but on the right it would create one single cluster containing all of the points(red), but I would like to obtain 2 clusters even on the right. So my question is: is there any kind of way to calculate dynamically the epsilon value to get this result? Thank you very much and excuse my for my poor english. Marco

    Read the article

  • Bidirectional/Loopback UDP in .net

    - by Jason Williams
    I've got an app that needs to transmit and receive on the same port. This can happen in two cases: Where the PC is talking to a piece of remote hardware. It "replies to sender", so the datagrams come back in to my PC via the sending port. Where the PC is talking to itself (loopback mode) for testing and demoing (a test app feeds fake data into our main app via UDP). This only seems to fail when trying to achieve loopback. The only way I can get it working is to ensure that the receiver is set up first - something I cannot guarantee. Can anyone help narrow down my search by suggesting a "correct" way to implement the UdpClient(s) to handle the above situations reliably? (The only solution that I've found to work reliably with the remote hardware is to use a single UdpClient in a bidirectional manner, although I'm working with legacy code that may be influencing that finding. I've tried using two UdpClients, but they step on each others toes - In some cases, once one client is started up, the other client cannot connect. With ExclusiveAddressUse/ReuseAddress set up to allow port sharing, I can almost get it to work, apart from the receiver having to start first)

    Read the article

  • How can you transform a set of numbers into mostly whole ones?

    - by Alice
    Small amount of background: I am working on a converter that bridges between a map maker (Tiled) that outputs in XML, and an engine (Angel2D) that inputs lua tables. Most of this is straight forward However, Tiled outputs in pixel offsets (integers of absolute values), while Angel2D inputs OpenGL units (floats of relative values); a conversion factor between these two is needed (for example, 32px = 1gu). Since OpenGL units are abstract, and the camera can zoom in or out if the objects are too small or big, the actual conversion factor isn't important; I could use a random number, and the user would merely have to zoom in or out. But it would be best if the conversion factor was selected such that most numbers outputted were small and whole (or fractions of small whole numbers), because that makes it easier to work with (and the whole point of the OpenGL units is that they are easy to work with). How would I find such a conversion factor reliably? My first attempt was to use the smallest number given; this resulted in no fractions below 1, but often lead to lots of decimal places where the factors didn't line up. Then I tried the mode of the sequence, which lead to the largest number of 1's possible, but often lead to very long floats for background images. My current approach gets the GCD of the whole sequence, which, when it works, works great, but can easily be thrown off course by a single bad apple. Note that while I could easily just pass the numbers I am given along, or pick some fixed factor, or use one of the conversions I specified above, I am looking for a method to reliably scale this list of integers to small, whole numbers or simple fractions, because this would most likely be unsurprising to the end user; this is not a one off conversion. The end users tend to use 1.0 as their "base" for manipulations (because it's simple and obvious), so it would make more sense for the sizes of entities to cluster around this.

    Read the article

  • How to exit current activity to homescreen (without using "Home" button)?

    - by steff
    Hi everyone, I am sure this will have been answered but I proved unable to find it. So please excuse my redundancy. What I am trying to do is emulating the "Home" button which takes one back to Android's homescreen. So here is what causes me problems: I have 3 launcher activities. The first one (which is connected to the homescreen icon) is just a (password protected) configuration activity. It will not be used by the user (just admin) One of the other 2 (both accessed via an app widget) is a questionnaire app. I'm allowing to jump back between questions via the Back button or a GUI back button as well. When the questionnaire is finished I sum up the answers given and provide a "Finish" button which should take the user back to the home screen. For the questionnaire app I use a single activity (called ItemActivity) which calls itself (is that recursion as well when using intents?) to jump from one question to another: Questionnaire.serializeToXML(); Intent i = new Intent().setClass(c, ItemActivity.class); if(Questionnaire.instance.getCurrentItemNo() == Questionnaire.instance.getAmountOfItems()) { Questionnaire.instance.setCompleted(true); } else Questionnaire.instance.nextItem(); startActivity(i); The final screen shows something like "Thank you for participating" as well as the formerly described button which should take one back to the homescreen. But I don't really get how to exit the Activity properly. I've e.g. used this.finish(); but this strangely brings up the "Thank you" screen again. So how can I just exit by jumping back to the homescreen?? Sorry for the inconvinience. Regards, Steff

    Read the article

  • Having trouble with confusing behaviour of error between debug and release modes in Xcode

    - by Cocorico
    Hi guys, I am confused over something (what is new!). I have an iPhone program I am writing and using some sqlite in a certain method, and there is some error which is giving me a message that says "Program received signal: “EXC_BAD_ACCESS” Okay, so I am trying to hunt down why this is doing this, and I notice something: When I run the program in debug mode, it gives me this error every single time I access this method (I test on the device). However when I run the program in release mode, I can access this method 2 times, and then it will give me this error the third time. So I mean, can someone just give me an explanation of what might cause this, I think that maybe deep-down I am not that smart on the difference in XCode of debug and release modes. I think that release mode does optimizing, and I guess the actual assembly machine code comes out different, yes? I AM A BIG NEWBIE USER UNFORTUNATELY! I am not clear on a lot of things like this, or whether it needs for I to remove nslog commands in the release build and such. Maybe I should just post the actual code in separate Stack OVerflow post, and see if people can see the error, then maybe this all become clear to me.

    Read the article

  • Core Data: Overkill for simple, static UITableView-based iPhone App?

    - by David Foster
    Hello! I have a rather simple iPhone app consisting of numerous views containing a single, grouped table view. These views are held together in navigation controllers which are grouped in a tab bar. Simple stuff. My table views do little more than list text (like "Dog", "Cat" and "Weasel") and this data is being served from a collection of plists. It's perhaps worth mentioning too that these tables are 'static' in the sense that their data is pre-determined and will only ever be amended—and if so, very rarely indeed—by the developer (in this case, moi). This rudimentary approach has reached its limits though, and I think I'm going to need something a bit more relational. I have worked a tad with Core Data in the past, but only with apps whose data is determined by user input. I have four closely related questions: Is Core Data overkill for an app consisting mainly of a selection of simple table views? Do you recommend using Core Data to manage data which is predetermine and extremely unlikely to ever change? Can one lock Core Data down so that its data can't change, thereby relinquishing my responsibility as the developer to handle the editing and saving of the managed object context? How do I go about giving Core Data my predetermined data, and in a format I know that it can work with? Thanks a bunch guys.

    Read the article

  • Timer Service in ejb 3.1 - schedule calling timeout problem

    - by Greg
    Hi Guys, I have created simple example with @Singleton, @Schedule and @Timeout annotations to try if they would solve my problem. The scenario is this: EJB calls 'check' function every 5 secconds, and if certain conditions are met it will create single action timer that would invoke some long running process in asynchronous fashion. (it's sort of queue implementation type of thing). It then continues to check, but as long as long running process is there it won't start another one. Below is the code I came up with, but this solution does not work, because it looks like asynchronous call I'm making is in fact blocking my @Schedule method. @Singleton @Startup public class GenerationQueue { private Logger logger = Logger.getLogger(GenerationQueue.class.getName()); private List<String> queue = new ArrayList<String>(); private boolean available = true; @Resource TimerService timerService; @Schedule(persistent=true, minute="*", second="*/5", hour="*") public void checkQueueState() { logger.log(Level.INFO,"Queue state check: "+available+" size: "+queue.size()+", "+new Date()); if (available) { timerService.createSingleActionTimer(new Date(), new TimerConfig(null, false)); } } @Timeout private void generateReport(Timer timer) { logger.info("!!--timeout invoked here "+new Date()); available = false; try { Thread.sleep(1000*60*2); // something that lasts for a bit } catch (Exception e) {} available = true; logger.info("New report generation complete"); } What am I missing here or should I try different aproach? Any ideas most welcome :) Testing with Glassfish 3.0.1 latest build - forgot to mention

    Read the article

  • Creating ODT and PDF files as end result

    - by Bill Zimmerman
    Hello, I've been working on an app to create various document formats for a while now, and I've had limited success. Ideally, I'd like to dynamically create a fairly simple ODT/PDF/DOC file. I've been focusing my efforts on ODT, because it is editable, and open enough that there are several tools which will convert it to any of the other formats I need. The problem is that the ODT XML files are NOT simple, and there aren't any good-quality API's I could find (especially in python). So far, I've had the most success creating a template ODT file, and then manipulating the DOM in python as needed. This is ok generally, but is quickly becoming inadequate and requires too much tweaking every single time I need to alter one of the templates. The requirements are: 1) Produce a simple document that will have lists, paragraphs, and the ability to draw simple graphics on the page (boxes, circles, etc...) 2) The ability to specify page size, and the different formats should generally print the exact same output when sent to a printer My questions: 1) Are there any other ways I can produce ODT/PDF/DOC files? 2) Would LaTeX be acceptable? I've never really used it, does anyone have experience converting LaTeX files into other formats? 3) Would it be possible to use HTML? There are a lot of converters online. Technically you can specify dimensions in mm/cm, etc..., but I am worried that the printed output will differ between browsers/converters.... Any other ideas?

    Read the article

  • Passing in a lambda to a Where statement

    - by sonicblis
    I noticed today that if I do this: var items = context.items.Where(i => i.Property < 2); items = items.Where(i => i.Property > 4); Once I access the items var, it executes only the first line as the data call and then does the second call in memory. However, if I do this: var items = context.items.Where(i => i.Property < 2).Where(i => i.Property > 4); I get only one expression executed against the context that includes both where statements. I have a host of variables that I want to use to build the expression for the linq lambda, but their presence or absence changes the expression such that I'd have to have a rediculous number of conditionals to satisfy all cases. I thought I could just add the Where() statements as in my first example above, but that doesn't end up in a single expression that contains all of the criteria. Therefore, I'm trying to create just the lambda itself as such: //bogus syntax if (var1 == "something") var expression = Expression<Func<item, bool>>(i => i.Property == "Something); if (var2 == "somethingElse") expression = expression.Where(i => i.Property2 == "SomethingElse"); And then pass that in to the where of my context.Items to evaluate. A) is this right, and B) if so, how do you do it?

    Read the article

  • Persistant Http client connections in java

    - by Akusete
    I am trying to write a simple Http client application in Java and am a bit confused by the seemingly different ways to establish Http client connections, and efficiently re-use the objects. Current I am using the following steps (I have left out exception handling for simplicity) Iterator<URI> uriIterator = someURIs(); HttpClient client = new DefaultHttpClient(); while (uriIterator.hasNext()) { URI uri = uriIterator.next(); HttpGet request = new HttpGet(uri); HttpResponse response = client.execute(request); HttpEntity entity = response.getEntity(); InputStream s = entity.getContent(); processStream (); s.close(); } In regard to the code above, my questions is: Assuming all URI's are pointing to the same host (but different resources on that host). What is the recommended way to use a single http connection for all requests? And how do you close the connection after the last request? --edit: Also what is the difference between using uri.openConnection(), versus HttpClient? Which is preferable, and what other methods exist?

    Read the article

  • Associating an object with another object for GC clearup

    - by thecoop
    Is there any way of associating an object instance (object A) with a second object (object B) in a generalised way, so that when B gets collected A becomes eligable for collection? The same behaviour that would happen if B had an instance variable pointing to A, but without explicitly changing the class definition of B, and being able to do this in a dynamic way? The same sort of effect could be done by using the Component.Disposed event in a funky way, but I don't want to make B disposable EDIT I'm basically creating a cache of objects that are associated with a single 'root' object, and I don't want the cache to be static, as there can be lots of root objects using different caches, so lots of memory will be used up when a root object is no longer used but the cached objects are still around. So, I want a collection of cached objects to be associated with each 'root' object, without changing the root object definition. Sort of like metadata of an extra object reference attached to each root object instance. That way, each collection will get collected when the root object is collected, and not hang around like they would if a static cache was used.

    Read the article

  • How to create a "Shell IDList Array" to support drag-and-drop of virtual files from C# to Windows Ex

    - by JustABill
    I started trying to implement drag-and-drop of virtual files (from a C# 4/WPF app) with this codeplex tutorial. After spending some time trying to figure out a DV_E_FORMATETC error, I figured out I need to support the "Shell IDList Array" data format. But there seems to be next to zero documentation on what this format actually does. After some searching, I found this page on advanced data transfer which said that a Shell IDList Array was a pointer to a CIDA structure. This CIDA structure then contains the number of PIDLs, and a list of offsets to them. So what the hell is a PIDL? After some more searching, this page sort of implies it's a pointer to an ITEMIDLIST, which itself contains a single member that is a list of SHITEMIDs. My next idea was to try dragging a file from another application with virtual files. I just got a MemoryStream back for this format. At least I know what class to provide for the thing, but that doesn't help at all for explaining what to put in it. So now that that's explained, I still have no idea how to create one of these things so that it's valid. There's two real questions here: What is a valid "abID" member for a SHITEMID? These virtual files only exist with my program; will the thing they are dragged to pass the "abID" back later when it executes GetData? Do they have to be system-unique? Why are there two levels of lists; a list of PIDLs and each PIDL has a list of SHITEMIDs? I'm assuming one of them is one for each file, but what's the other one for? Multiple IDs for the same file? Any help or even links that explain what I should be doing would be greatly appreciated.

    Read the article

  • How to calculate the height of the text rectangle from an NSString?

    - by mystify
    I know there is this one: sizeWithFont:minFontSize:actualFontSize:forWidth:lineBreakMode: But since the CGSize always has the same height and doesn't adjust to any shrinked text or whatsoever, the CGSize is not telling how heigh the text is. Example: Make a UILabel with 320 x 55 points and put a loooooooooooooong text in there. Let the label shrink the text down. Surprise: CGSize.height remains the same height even if the text is so tiny that you need a microscope. Ok so after banging my head against my macbook pro which is half way broken now, the only think that can help is that nasty actualFontSize. But the font size is in pica I think, it's not really what you get on the screen, isn't it? When that font size is 10, is my text really 10 points heigh at maximum? Once in a while I tried exactly that, and as soon as the text had a y or some character that extends to below (like that tail of an y does), it is out of bounds and the whole text is bigger than 10 points. So how would you calculate the real text height for a single line uilabel without getting a long beard and some hospital experience?

    Read the article

  • JSF: Avoid nested update calls

    - by dhroove
    I don't know if I am on right track or not still asking this question. I my JSF project I have this tree structure: <p:tree id="resourcesTree" value="#{someBean.root}" var="node" selectionMode="single" styleClass="no-border" selection="#{someBean.selectedNode}" dynamic="true"> <p:ajax listener="#{someBean.onNodeSelect}" update=":centerPanel :tableForm :tabForm" event="select" onstart="statusDialog.show();" oncomplete="statusDialog.hide();" /> <p:treeNode id="resourcesTreeNode" > <h:outputText value="#{node}" id="lblNode" /> </p:treeNode> </p:tree> I have to update this tree after I added something or delete something.. But whenever I update this still its nested update also call I mean to say it also call to update these components ":centerPanel :tableForm :tabForm"... This give me error that :tableForm not found in view because this forms load in my central panel and this tree is in my right panel.. So when I am doing some operation on tree is it not always that :tableForm is in my central panel.. (I mean design is something like this only) So now my question is that can I put some condition or there is any way so that I can specify when to update nested components also and when not.... In nut shell is there any way to update only :resoucesTree is such a way that nested updates are not called so that I can avoid error... Thanks in advance.

    Read the article

  • wpf 4 datagrid not highlighting row.

    - by SteveCav
    I have a shiny new wpf 4 datagrid, and no matter what I do I can't make the row highlight when the user clicks on a cell. It works on the empty "new record" row on the bottom, but not on rows with data (yes I've tried with and without readonly). My XAML is: <DataGrid AutoGenerateColumns="False" Background="Beige" Height="353" SelectionUnit="FullRow" SelectionMode="Single" AlternatingRowBackground="lightcyan" HorizontalAlignment="Left" Name="dgJobs" VerticalAlignment="Top" Width="1160"> <DataGrid.Columns> <DataGridTextColumn Header="Job ID" Width="80" Binding="{Binding JobID}" IsReadOnly="True"></DataGridTextColumn> <DataGridTextColumn Header="Site" Width="SizeToCells" Binding="{Binding AssetName}" IsReadOnly="True"></DataGridTextColumn> <DataGridTextColumn Header="Category" Width="SizeToCells" Binding="{Binding CategoryName}" IsReadOnly="True"></DataGridTextColumn> <DataGridTextColumn Header="Status" Width="SizeToCells" Binding="{Binding JobStatusDesc}" IsReadOnly="True"></DataGridTextColumn> <DataGridTextColumn Header="Reason" Width="SizeToCells" Binding="{Binding Reason}" IsReadOnly="True"></DataGridTextColumn> </DataGrid.Columns> </DataGrid> Nothing too fancy, it's quite plain really. I had themes enabled because I'm using a Fluent Ribbon elsewhere and it forces you to, but I tried turning that off and it had no effect. I have a 3.5 form in another app which is also very plain and you can highlight the row on it. Why on earth isn't this one working?

    Read the article

  • C++: select argmax over vector of classes w.r.t. arbitrary expression

    - by karpathy
    Hello, I have trouble describing my problem so I'll give an example: I have a class description that has a couple of variables in it, for example: class A{ float a, b, c, d; } Now, I maintain a vector<A> that contains many of these classes. What I need to do very very often is to find the object inside this vector that satisfies that one of it's parameters is maximal w.r.t to the others. i.e code looks something like: int maxi=-1; float maxa=-1000; for(int i=0;i<vec.size();i++){ res= vec[i].a; if(res > maxa) { maxa= res; maxi=i; } } return vec[maxi]; However, sometimes I need to find class with maximal a, sometimes with maximal b, sometimes the class with maximal 0.8*a + 0.2*b, sometimes I want a maximal a*VAR + b, where VAR is some variable that is assigned in front, etc. In other words, I need to evaluate an expression for every class, and take the max. I find myself copy-pasting this everywhere, and only changing the single line that defines res. What makes it even more complicated is that even the name of the vector changes. Sometimes it's vec, sometimes it can be something else. I have many vectors that contain A's. This could be changed if this makes the problem too hard. Is there some nice way to avoid this insanity in C++? What's the neatest way to handle this? Thank you!

    Read the article

  • Technical choices in unmarshaling hash-consed data

    - by Pascal Cuoq
    There seems to be quite a bit of folklore knowledge floating about in restricted circles about the pitfalls of hash-consing combined with marshaling-unmarshaling of data. I am looking for citable references to these tidbits. For instance, someone once pointed me to library aterm and mentioned that the authors had clearly thought about this and that the representation on disk was bottom-up (children of a node come before the node itself in the data stream). This is indeed the right way to do things when you need to re-share each node (with a possible identical node already in memory). This re-sharing pass needs to be done bottom-up, so the unmarshaling itself might as well be, too, so that it's possible to do everything in a single pass. I am in the process of describing difficulties encountered in our own context, and the solutions we found. I would appreciate any citable reference to the kind of aforementioned folklore knowledge. Some people obviously have encountered the problems before (the aterm library is only one example). But I didn't find anything in writing. Even the little piece of information I have about aterm is hear-say. I am not worried it's not reliable (you can't make this up), but "personal communication" and "look how it's done in the source code" are considered poor form in citations. I have enough references on hash-consing alone. I am only interested in references where it interferes with other aspects of programming, such as marshaling or distribution.

    Read the article

  • How to approach parallel processing of messages?

    - by Dan
    I am redesigning the messaging system for my app to use intel threading building blocks and am stumped trying to decide between two possible approaches. Basically, I have a sequence of message objects and for each message type, a sequence of handlers. For each message object, I apply each handler registered for that message objects type. The sequential version would be something like this (pseudocode): for each message in message_sequence <- SEQUENTIAL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The first approach which I am considering processes the message objects in turn (sequentially) and applies the handlers concurrently. Pros: predictable ordering of messages (ie, we are guaranteed a FIFO processing order) (potentially) lower latency of processing each message Cons: more processing resources available than handlers for a single message type (bad parallelization) bad use of processor cache since message objects need to be copied for each handler to use large overhead for small handlers The pseudocode of this approach would be as follows: for each message in message_sequence <- SEQUENTIAL parallel_for each handler in (handler_table for message.type) apply handler to message <- PARALLEL The second approach is to process the messages in parallel and apply the handlers to each message sequentially. Pros: better use of processor cache (keeps the message object local to all handlers which will use it) small handlers don't impose as much overhead (as long as there are other handlers also to be run) more messages are expected than there are handlers, so the potential for parallelism is greater Cons: Unpredictable ordering - if message A is sent before message B, they may both be processed at the same time, or B may finish processing before all of A's handlers are finished (order is non-deterministic) The pseudocode is as follows: parallel_for each message in message_sequence <- PARALLEL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The second approach has more advantages than the first, but non-deterministic ordering is a big disadvantage.. Which approach would you choose and why? Are there any other approaches I should consider (besides the obvious third approach: parallel messages and parallel handlers, which has the disadvantages of both and no real redeeming factors as far as I can tell)? Thanks!

    Read the article

  • Fetch the most viewed data in databases

    - by Erik Edgren
    I want to get the most viewed photo from the database but I don't know how I shall accomplish this. Here's my SQL at the moment: SELECT * FROM photos AS p, viewers AS v WHERE p.id = v.id_photo GROUP BY v.id_photo The databases: CREATE TABLE IF NOT EXISTS `photos` ( `id` int(10) NOT NULL AUTO_INCREMENT, `photo_filename` varchar(50) NOT NULL, `photo_camera` varchar(150) NOT NULL, `photo_taken` datetime NOT NULL, `photo_resolution` varchar(10) NOT NULL, `photo_exposure` varchar(10) NOT NULL, `photo_iso` varchar(3) NOT NULL, `photo_fnumber` varchar(10) NOT NULL, `photo_focallength` varchar(10) NOT NULL, `post_coordinates` text NOT NULL, `post_description` text NOT NULL, `post_uploaded` datetime NOT NULL, `post_edited` datetime NOT NULL, `checkbox_approxcoor` enum('0','1') NOT NULL DEFAULT '0', PRIMARY KEY (`id`), UNIQUE KEY `id` (`id`) ) CREATE TABLE IF NOT EXISTS `viewers` ( `id` int(10) NOT NULL AUTO_INCREMENT, `id_photo` int(10) DEFAULT '0', `ipaddress` text NOT NULL, `date_viewed` datetime NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `id` (`id`) ) The data in viewers looks like this: (1, 85, '3892a0ab97d6ff325f285b27b847070f', '2012-06-21 22:49:25'), (2, 84, '3892a0ab97d6ff325f285b27b847070f', '2012-06-21 22:49:25'), (3, 85, '3892a0ab97d6ff325f285b27b847070f', '2012-06-21 22:49:25'); One single row from the database for photos to understand how the rows looks like in this database: (85, 'P1170986.JPG', 'Panasonic DMC-LX3', '2012-06-19 18:00:40', '3968x2232', '10/8000', '80', '50/10', '51/10', '', '', '2012-06-19 18:45:17', '0000-00-00 00:00:00', '0') At the moment the SQL only prints the photo with ID 84. In this case it's wrong - it should print out the photo with ID 85. How can I fix this problem? Thanks in advance.

    Read the article

  • Using Everyauth/Express and Multiple Configurations?

    - by Zane Claes
    I'm successfully using Node.js + Express + Everyauth ( https://github.com/abelmartin/Express-And-Everyauth/blob/master/app.js ) to login to Facebook, Twitter, etc. from my application. The problem I'm trying to wrap my head around is that Everyauth seems to be "configure and forget." I set up a single everyauth object and configure it to act as middleware for express, and then forget about it. For example, if I want to create a mobile Facebook login I do: var app = express.createServer(); everyauth.facebook .appId('AAAA') .appSecret('BBBB') .entryPath('/login/facebook') .callbackPath('/callback/facebook') .mobile(true); // mobile! app.use(everyauth.middleware()); everyauth.helpExpress(app); app.listen(8000); Here's the problem: Both mobile and non-mobile clients will connect to my server, and I don't know which is connecting until the connection is made. Even worse, I need to support multiple Facebook app IDs (and, again, I don't know which one I will want to use until the client connects and I partially parse the input). Because everyauth is a singleton which in configured once, I cannot see how to make these changes to the configuration based upon the request that is made. What it seems like is that I need to create some sort of middleware which acts before the everyauth middleware to configure the everyauth object, such that everyauth subsequently uses the correct appId/appSecret/mobile parameters. I have no clue how to go about this... Suggestions? Here's the best idea I have so far, though it seems terrible: Create an everyauth object for every possible configuration using a different entryPath for each...

    Read the article

  • Counting string length in javascript and Ruby on Rails

    - by williamjones
    I've got a text area on a web site that should be limited in length. I'm allowing users to enter 255 characters, and am enforcing that limit with a Rails validation: validates_length_of :body, :maximum => 255 At the same time, I added a javascript char counter like you see on Twitter, to give feedback to the user on how many characters he has already used, and to disable the submit button when over length, and am getting that length in Javascript with a call like this: element.length Lastly, to enforce data integrity, in my Postgres database, I have created this field as a varchar(255) as a last line of defense. Unfortunately, these methods of counting characters do not appear to be directly compatible. Javascript counts the best, in that it counts what users consider as number of characters where everything is a single character. Once the submission hits Rails, however, all of the carriage returns have been converted to \r\n, now taking up 2 characters worth of space, which makes a close call fail Rails validations. Even if I were to handcode a different length validation in Rails, it would still fail when it hits the database I think, though I haven't confirmed this yet. What's the best way for me to make all this work the way the user would want? Best Solution: an approach that would enable me to meet user expectations, where each character of any type is only one character. If this means increasing the length of the varchar database field, a user should not be able to sneakily send a hand-crafted post that creates a row with more than 255 letters. Somewhat Acceptable Solution: a javascript change that enables the user to see the real character count, such that hitting return increments the counter 2 characters at a time, while properly handling all symbols that might have these strange behaviors.

    Read the article

< Previous Page | 552 553 554 555 556 557 558 559 560 561 562 563  | Next Page >