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  • Serialization for memcached

    - by Ram
    I have this huge domain object(say parent) which contains other domain objects. It takes a lot of time to "create" this parent object by querying a DB (OK we are optimizing the DB). So we decided to cache it using memcached (with northscale to be specific) So I have gone through my code and marked all the classes (I think) as [Serializable], but when I add it to the cache, I see a Serialization Exception getting thrown in my VS.net output window. var cache = new NorthScaleClient("MyBucket"); cache.Store(StoreMode.Set, key, value); This is the exception: A first chance exception of type 'System.Runtime.Serialization.SerializationException' occurred in mscorlib.dll SO my guess is, I have not marked all classes as [Serializable]. I am not using any third party libraries and can mark any class as [Serializable], but how do I find out which class is failing when the cache is trying to serialize the object ? Edit1: casperOne comments make me think. I was able to cache these domain object with Microsoft Cache Application Block without marking them [Serializable], but not with NorthScale memcached. It makes me think that there might be something to do with their implementation, but just out of curiosity, am still interested in finding where it fails when trying to add the object to memcached

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  • iPhone application purchase verification -- possible?

    - by Sedate Alien
    The iPhone 3.0 SDK's StoreKit.framework provides support for in-app purchases to give the user additional content, functionality and so on. It is possible for an app to send the transactionReceipt property of SKPaymentTransaction objects to the developer's server for verification of successful purchasing before granting service. Is there any analogous SDK to verify the initial application purchase itself? A developer that wishes for their server to only provide services to genuine applications (i.e. not pirated) without using IAP could do so by verifying the application in this manner, e.g. ensure that only users with the correct transactionReceipt are catered for. I understand that this approach would still be vulnerable to replay attacks; a dedicated group of pirates could share a valid transactionReceipt. However, my server provides a consumable service to users, i.e. once they've connected and done the work, it needn't work a second time so replay attacks are nullified. The service that my app provides is relatively niche. I could distribute it on the App Store as a free application that requires at least one IAP to do anything useful, but I am lead to believe that this would be a very unpopular move among users as it would be considered misleading. If I distribute it as a paid app, I do not know how to ensure that only genuine apps can access the webservice. This is important as every invocation of the webservice costs me money! What are my options?

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  • Does Entity Framework saves related classes automatically?

    - by herbatnic
    Let's assume that we have such classes public class A{ string someField { get; set; } public virtual B B {get; set; } } public class B { int someIntField {get; set; } [ForeignKey("Id")] [Required] public virtual A A { get; set; } } In code I create new instances for both of them and making relation like: A a = new A () { someField = "abcd"}; B b = new B () { someIntField = 42 }; A.B = b; B.A = a; Should I using DBContext to save both classes like that: using (var db = new myDbContext()) { myDbContext.As.Add(A); myDbContext.Bs.Add(B); myDBContext.SaveChanges(); } Or saving it like that: using (var db = new myDbContext()) { myDbContext.As.Add(A); myDbContext.SaveChanges(); } is enough to store related objects into database?

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  • No result when Rally.data.WsapiDataStore lacks permissions

    - by user1195996
    I'm calling Ext.create('Rally.data.WsapiDataStore', params), and looking for results with the load event. I'm requesting a number of objects across programs that the user may or may not have read permission for. This works fine for queries where the user has permissions. But in the case where the user does not have permission and presumably gets zero results back, the load event does not seem to fire at all. I would expect it to fire with the unsuccessful flag or else to return with empty results. Since I don't know that the request has failed, my program waits and waits. How can I tell if a this request fails to return because of security? BTW, looking at the network stats, I believe all my requests get a "200 OK" status back. Here is the method I use to create the various data stores: _createDataStore: function(params) { this.openRequests++; var createParams = { model: params.type, autoLoad: true, // So I can later determine which query type it is, and which program requestType: params.requestType == undefined ? params.type : params.requestType, program: this.program, listeners: { load: this._onDataLoaded, scope: this }, filters: params.filters, pageSize: params.pageSize, fetch: params.fetch, context: { project: this.project, projectScopeUp: false, projectScopeDown: true }, pageSize: 1 // We only need the count }; console.log('_createDataStore', this.program, createParams.requestType); Ext.create('Rally.data.WsapiDataStore', createParams); }, And here is the _onDataLoaded method: _onDataLoaded: function(store, data, successB) { console.log('_onDataLoaded', this.program, successB); ... I only see this function called for those queries for which the account has permissions.

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  • Dealing with large number of text strings

    - by Fadrian
    My project when it is running, will collect a large number of string text block (about 20K and largest I have seen is about 200K of them) in short span of time and store them in a relational database. Each of the string text is relatively small and the average would be about 15 short lines (about 300 characters). The current implementation is in C# (VS2008), .NET 3.5 and backend DBMS is Ms. SQL Server 2005 Performance and storage are both important concern of the project, but the priority will be performance first, then storage. I am looking for answers to these: Should I compress the text before storing them in DB? or let SQL Server worry about compacting the storage? Do you know what will be the best compression algorithm/library to use for this context that gives me the best performance? Currently I just use the standard GZip in .NET framework Do you know any best practices to deal with this? I welcome outside the box suggestions as long as it is implementable in .NET framework? (it is a big project and this requirements is only a small part of it) EDITED: I will keep adding to this to clarify points raised I don't need text indexing or searching on these text. I just need to be able to retrieve them in later stage for display as a text block using its primary key. I have a working solution implemented as above and SQL Server has no issue at all handling it. This program will run quite often and need to work with large data context so you can imagine the size will grow very rapidly hence every optimization I can do will help.

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  • Multiple Foreign keys to a single table and single key pointing to more than one table

    - by user1216775
    I need some suggestions from the database design experts here. I have around six foreign keys into a single table (defect) which all point to primary key in user table. It is like: defect (.....,assigned_to,created_by,updated_by,closed_by...) If I want to get information about the defect I can make six joins. Do we have any better way to do it? Another one is I have a states table which can store one of the user-defined set of values. I have defect table and task table and I want both of these tables to share the common state table (New, In Progress etc.). So I created: task (.....,state_id,type_id,.....) defect(.....,state_id,type_id,...) state(state_id,state_name,...) importance(imp_id,imp_name,...) There are many such common attributes along with state like importance(normal, urgent etc), priority etc. And for all of them I want to use same table. I am keeping one flag in each of the tables to differentiate task and defect. What is the best solution in such a case? If somebody is using this application in health domain, they would like to assign different types, states, importances for their defect or tasks. Moreover when a user selects any project I want to display all the types,states etc under configuration parameters section.

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  • Detect if Download is Complete

    - by user604138
    I have a very simple and standard PHP force download script. How do I check if/when the download has completed in order to notify the user on the clientside? I don't even need to show the progress in real time, I am only interested in the very specific event: "when the download completes". Based on my research, it seems like it would have to be determined from the serverside as there is noondownloadready event and I don't think it is possible to intercept browser events. So it seems that my best bet would be to compare bytes sent to total bytes with some sort of clientside/severside interaction. How would I go about checking the bytes sent from the server for a PHP forced download? is there some sort of global PHP variable that store these data that I can ping with AJAX? <?php header("Content-Type: video/x-msvideo"); header("Content-Disposition: attachment; filename=\"".basename($realpath)."\";"); ... $chunksize = 1 * (1024 * 1024); // how many bytes per chunk if ($size > $chunksize) { $handle = fopen($realpath, 'rb'); $buffer = ''; while (!feof($handle)) { $buffer = fread($handle, $chunksize); echo $buffer; ob_flush(); flush(); } fclose($handle); } else { readfile($realpath); } exit(); ?> The reason I need this: For the project I am working on, it is required that after the download starts, the page redirects to (or displays) a "please wait while the download completes" page. Then, once it is complete, it should redirect to (or display) a "Your download is complete, thank you" page. I am open to other ideas that would achieve the same result.

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  • rails + paperclip: Is a generic "Attachment" model a good idea?

    - by egarcia
    On my application I've several things with attachments on them, using paperclip. Clients have one logo. Stores can have one or more pictures. These pictures, in addition, can have other information such as the date in which they were taken. Products can have one or more pictures of them, categorized (from the font, from the back, etc). For now, each one of my Models has its own "paperclip-fields" (Client has_attached_file) or has_many models that have attached files (Store has_many StorePictures, Product has_many ProductPictures) My client has also told me that in the future we might be adding more attachments to the system (i.e. pdf documents for the clients to download). My application has a rather complex authorization system implemented with declarative_authorization. One can not, for example, download pictures from a product he's not allowed to 'see'. I'm considering re-factoring my code so I can have a generic "Attachment" model. So any model can has_many :attachments. With this context, does it sound like a good idea? Or should I continue making Foos and FooPictures?

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  • Recommendation for a Pagination procedure AJAX PHP

    - by Jamex
    Hi, I am not sure the correct terminology for the process that I am trying to describe. I don't even know which platform is underlying the technique. If you understand my description, please give the link to the site(s) and or the keyword name of the process. I think it is done by AJAX, but I am not certain. I use php as the backend code, I just need to find a way to dynamically display the results. Please give suggestions. I forgot the name of the sites that use this, and my link history expired. TIA Description: The page would have a search form and options. After the user submits, the search is initiated, and the results appear inside the dedicated result area. The page does not refresh, just the info inside the result area. The display area will show 20 (or whatever) results (lines). There will be next, and previous buttons. If you hit next, the next set of results will display. I am writing a code that generates 20 results for each display. There is no set number of results, so the results might have a start/first page, but do not have an end page. Each time the user hits 'next', the program would generate/load new results. It would also store previous results, so that when a user hits 'prev', the previous results can instantly come up. What techniques/program are theses?

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  • What is wrong with this append func in C

    - by LuckySlevin
    My Struct Definitions. typedef struct inner_list {char word[100]; inner_list*next;} inner_list; typedef struct outer_list { char word [100]; inner_list * head; outer_list * next; } outer_list; And The problem part: void append(outer_list **q,char num[100],inner_list *p) { outer_list *temp,*r; temp = *q; char *str; if(*q==NULL) { temp = (outer_list *)malloc(sizeof(outer_list)); strcpy(temp->word,num); temp->head = p; temp->next=NULL; *q=temp; } else { temp = *q; while(temp->next !=NULL) { temp=temp->next; } r = (outer_list *)malloc(sizeof(outer_list)); strcpy(r->word,num); temp->head = p; r->next=NULL; temp->next=r; } } I don't know what is i'm doing wrong in this append function i'm sending a char array and a linked list to be stored another linked list. But i can't store the linked list in another linked list. I couldn't figure out the problem. Any ideas?

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  • why my form is doing postback when i am calling asynchronously?

    - by Abu Hamzah
    i am using simple asp.net webpage with few fields on it and when the user click on submit button i am calling asynchronously and posting the data. BUT, my whole page is posting back and i dont even see the message that i am trying to display if my data got posted succfully. here is my page. Requester Page Name: <asp:Label runat="server" ID='Label4' >Host Name:</asp:Label> <asp:TextBox ID="txtHost" runat='server'></asp:TextBox> <asp:Label runat="server" ID='Label2' >Start Date:</asp:Label> <asp:TextBox ID="txtStartDate" runat='server' ></asp:TextBox> <asp:Label runat="server" ID='Label6' >End Date:</asp:Label> <asp:TextBox ID="txtEndDate" runat='server' ></asp:TextBox> <ul> <li> <button id="btnCancel" name="btnCancel" type="button"> Cancel</button></li> <li> <button id="btnReset" name="btnReset" type="reset"> Reset</button></li> <li> <button id="btnSubmit" name="btnSubmit" type="submit"> Submit</button></li> </ul> </p> </form> </div> //Store new Contract Request Methods function processCompletedContactStore(response) { if (!response) { showErrorMsg('No Contacts Returned'); return; } else { if (response.Message == 'update') { $("#status").fadeTo(500, 1, function() { $(this).html("Updated successfully!").fadeTo(500, 150); }) } } }

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  • Peculiar JRE behaviour running RMI server under load, should I worry?

    - by darri
    I've been developing a minimalistic Java rich client CRUD application framework for the past few years, mostly as a hobby but also actively using it to write applications for my current employer. The framework provides database access to clients either via a local JDBC based connection or a lightweight RMI server. Last night I started a load testing application, which ran 100 headless clients, bombarding the server with requests, each client waiting only 1 - 2 seconds between running simple use cases, consisting of selecting records along with associated detail records from a simple e-store database (Chinook). This morning when I looked at the telemetry results from the server profiling session I noticed something which to me seemed strange (and made me keep the setup running for the remainder of the day), I don't really know what conclusions to draw from it. Here are the results: Memory GC activity Threads CPU load Interesting, right? So the question is, is this normal or erratic? Is this simply the JRE (1.6.0_03 on Windows XP) doing it's thing (perhaps related to the JRE configuration) or is my framework design somehow causing this? Running the server against MySQL as opposed to an embedded H2 database does not affect the pattern. I am leaving out the details of my server design, but I'll be happy to elaborate if this behaviour is deemed erratic.

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  • How to gracefully handle YouTube thumbnail broken images when videos are taken down?

    - by mrjf
    Our site contains some lists of YouTube videos with their thumbnails linked to the movies themselves. We fetch the thumbnail URLs from the YouTube API, and hotlink to them in situ on YouTube's servers. So our image tags look like: <img src="http://i.ytimg.com/vi/o6CHqSN7O-o/2.jpg" alt="" width="133" height="78" /> The problem is that sometimes a video gets removed -- and so does the thumbnail. We don't know when that might happen, and our thumbnails just turn into broken images. How can we handle this? There are a number of solutions: Download thumbnails and store them locally -- movie won't work, but that's ok, it will explain it was removed, and we avoid the broken image Check periodically with the API to see if the image thumbnail has changed -- if it no longer exists, substitute our own "movie removed" thumbnail. This is pretty heavy on the API calling! Use JavaScript to replace broken images (don't like this one much) Our ideal solution would be to point the img src to a location on YouTube that would display a friendly "move removed" image when a movie goes down. However, that doesn't seem to exist. Anyone else dealt with this? Thanks!

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  • table column accepting "0" as a member Id

    - by user682417
    I have two tables one is members table with columns member id , member first name, member last name. I have another table guest passes with columns guest pass id and member id and issue date . I have a list view that will displays guest passes details (I.e) like member name and issue date and I have two text boxes those are for entering member name and issue date . member name text box is auto complete text box that working fine.... but the problem is when I am entering the name that is not in member table at this time it will accept and displays a blank field in list view in member name column and member id is stored as "0" in guest pass table ...... I don't want to display the member name empty blank and I don t want to store "0" in guest pass table and this is the insert statement sql2 = @"INSERT INTO guestpasses(member_Id,guestPass_IssueDate)"; sql2 += " VALUES("; sql2 += "'" + tbCGuestPassesMemberId.Text + "'"; sql2 += ",'" + tbIssueDate.Text + "'"; guestpassmemberId = memberid is there any validation that need to be done can any one suggestions on this pls... and this is the auto complete text box statement sql = @"SELECT member_Id FROM members WHERE concat(member_Firstname,'',member_Lastname) ='" + tbMemberName.Text+"'"; if (dt != null) { if (dt.Rows.Count > 0) { tbCGuestPassesMemberId.Text = Convert.ToInt32(dt.Rows[0] ["member_Id"]).ToString(); } } can any one help me on this ... is there any type of validation with sql query pls help me .....

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  • Where to start with the development of first database driven Web App (long question)?

    - by Ryan
    Hi all, I've decided to develop a database driven web app, but I'm not sure where to start. The end goal of the project is three-fold: 1) to learn new technologies and practices, 2) deliver an unsolicited demo to management that would show how information that the company stores as office documents spread across a cumbersome network folder structure can be consolidated and made easier to access and maintain and 3) show my co-workers how Test Drive Development and prototyping via class diagrams can be very useful and reduces future maintenance headaches. I think this ends up being a basic CMS to which I have generated a set of features, see below. 1) Create a database to store the site structure (organized as a tree with a 'project group'-project structure). 2) Pull the site structure from the database and display as a tree using basic front end technologies. 3) Add administrator privileges/tools for modifying the site structure. 4) Auto create required sub pages* when an admin adds a new project. 4.1) There will be several sub pages under each project and the content for each sub page is different. 5) add user privileges for assigning read and write privileges to sub pages. What I would like to do is use Test Driven Development and class diagramming as part of my process for developing this project. My problem; I'm not sure where to start. I have read on Unit Testing and UML, but never used them in practice. Also, having never worked with databases before, how to I incorporate these items into the models and test units? Thank you all in advance for your expertise.

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  • Pickled my dictionary from ZODB but i got a less in size one?

    - by Someone Someoneelse
    I use ZODB and i want to copy my 'database_1.fs' file to another 'database_2.fs', so I opened the root dictionary of that 'database_1.fs' and I (pickle.dump) it in a text file. Then I (pickle.load) it in a dictionary-variable, in the end I update the root dictionary of the other 'database_2.fs' with the dictionary-variable. It works, but I wonder why the size of the 'database_1.fs' not equal to the size of the other 'database_2.fs'. They are still copies of each other. def openstorage(store): #opens the database data={} data['file']=filestorage data['db']=DB(data['file']) data['conn']=data['db'].open() data['root']=data['conn'].root() return data def getroot(dicty): return dicty['root'] def closestorage(dicty): #close the database after Saving transaction.commit() dicty['file'].close() dicty['db'].close() dicty['conn'].close() transaction.get().abort() then that's what i do:- import pickle loc1='G:\\database_1.fs' op1=openstorage(loc1) root1=getroot(op1) loc2='G:database_2.fs' op2=openstorage(loc2) root2=getroot(op2) >>> len(root1) 215 >>> len(root2) 0 pickle.dump( root1, open( "save.txt", "wb" )) item=pickle.load( open( "save.txt", "rb" ) ) #now item is a dictionary root2.update(item) closestorage(op1) closestorage(op2) #after I open both of the databases #I get the same keys in both databases #But `database_2.fs` is smaller that `database_2.fs` in size I mean. >>> len(root2)==len(root1)==215 #they have the same keys True Note: (1) there are persistent dictionaries and lists in the original database_1.fs (2) both of them have the same length and the same indexes.

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  • creating a vector with references to some of the elements of another vector

    - by memC
    hi, I have stored instances of class A in a std:vector, vec_A as vec_A.push_back(A(i)). The code is shown below. Now, I want to store references some of the instances of class A (in vec_A) in another vector or another array. For example, if the A.getNumber() returns 4, 7, 2 , I want to put a reference to that instance of A in another vector, say std:vector<A*> filtered_A or an array. Can someone sow me how to do this?? Thanks! class A { public: int getNumber(); A(int val); ~A(){}; private: int num; }; A::A(int val){ num = val; }; int A::getNumber(){ return num; }; int main(){ int i =0; int num; std::vector<A> vec_A; for ( i = 0; i < 10; i++){ vec_A.push_back(A(i)); } std::cout << "\nPress RETURN to continue..."; std::cin.get(); return 0; }

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  • How can I pass an array resulting from a Perl method by reference?

    - by arareko
    Some XML::LibXML methods return arrays instead of references to arrays. Instead of doing this: $self->process_items($xml->findnodes('items/item')); I want to do something like: $self->process_items(\$xml->findnodes('items/item')); So that in process_items() I can dereference the original array instead of creating a copy: sub process_items { my ($self, $items) = @_; foreach my $item (@$items) { # do something... } } I can always store the results of findnodes() into an array and then pass the array reference to my own method, but let's say I want to try a reduced version of my code. Is that the correct syntax for passing the method results or should I use something different? Thanks! EDIT: Now suppose I want to change process_items() to process_item() so I can do stuff on a single element of the referenced array inside a loop. Something like: $self->process_item($_) for ([ $xml->findnodes('items/item') ]); This doesn't work as process_item() is executed only once because a single value is passed to the for loop (the reference to the array from findnodes()). What's the proper way of using $_ in this case?

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  • Create an index only on certain rows in mysql

    - by dhruvbird
    So, I have this funny requirement of creating an index on a table only on a certain set of rows. This is what my table looks like: USER: userid, friendid, created, blah0, blah1, ..., blahN Now, I'd like to create an index on: (userid, friendid, created) but only on those rows where userid = friendid. The reason being that this index is only going to be used to satisfy queries where the WHERE clause contains "userid = friendid". There will be many rows where this is NOT the case, and I really don't want to waste all that extra space on the index. Another option would be to create a table (query table) which is populated on insert/update of this table and create a trigger to do so, but again I am guessing an index on that table would mean that the data would be stored twice. How does mysql store Primary Keys? I mean is the table ordered on the Primary Key or is it ordered by insert order and the PK is like a normal unique index? I checked up on clustered indexes (http://dev.mysql.com/doc/refman/5.0/en/innodb-index-types.html), but it seems only InnoDB supports them. I am using MyISAM (I mention this because then I could have created a clustered index on these 3 fields in the query table). I am basically looking for something like this: ALTER TABLE USERS ADD INDEX (userid, friendid, created) WHERE userid=friendid

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  • Adding validations without knowing the fields

    - by Frexuz
    My example form <% form_for @ad do |f| %> <%= f.error_messages %> <p> <%= f.label :ad_type_id %><br /> <%= f.collection_select(:ad_type_id, AdType.all, :id, :name) %> </p> <p> <% @ad.ad_properties.each do |property| %> <%= property.name %>: <% f.fields_for :ad_values do |value_field| %> <%= value_field.text_field :ad_id, :value => @ad.id %> <%= value_field.text_field :ad_property_id, :value => property.id %> <%= value_field.text_field :value %> <% end %><br /><br /> <% end %> </p> <p> <%= f.label :description %><br /> <%= f.text_area :description %> </p> <p><%= f.submit %></p> <% end %> Explanation: Ad has many properties. I can add new properties at any time (it's a normal model). Lets say the Ad is of the type 'hotel'. Then I would add properties like 'stars' and 'breakfast_included' Then I store each of these properties' values in a separate model. And all this works fine with my form above. My problem: These fields are not validated because I can't know what their names are. I need to add validations dynamically somehow. My thought: #Before the normal validations kick in def add_validations self.properties.each do |property| property.add_validation :whatever #somehow :) end end How could I do this?

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  • How can I compare the performance of log() and fp division in C++?

    - by Ventzi Zhechev
    Hi, I’m using a log-based class in C++ to store very small floating-point values (as the values otherwise go beyond the scope of double). As I’m performing a large number of multiplications, this has the added benefit of converting the multiplications to sums. However, at a certain point in my algorithm, I need to divide a standard double value by an integer value and than do a *= to a log-based value. I have overloaded the *= operator for my log-based class and the right-hand side value is first converted to a log-based value by running log() and than added to the left-hand side value. Thus the operations actually performed are floating-point division, log() and floating-point summation. My question whether it would be faster to first convert the denominator to a log-based value, which would replace the floating-point division with floating-point subtraction, yielding the following chain of operations: twice log(), floating-point subtraction, floating-point summation. In the end, this boils down to whether floating-point division is faster or slower than log(). I suspect that a common answer would be that this is compiler and architecture dependent, so I’ll say that I use gcc 4.2 from Apple on darwin 10.3.0. Still, I hope to get an answer with a general remark on the speed of these two operators and/or an idea on how to measure the difference myself, as there might be more going on here, e.g. executing the constructors that do the type conversion etc. Cheers!

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  • Why doesn't Firefox redownload images already on a page?

    - by vvo
    Hello, i just read this article : https://developer.mozilla.org/en/HTTP_Caching_FAQ There's a firefox behavior (and some other browsers i guess) i'd like to understand : if i take any webpage and try to insert the same image multiple times in javascript, the image is only downloaded ONCE even if i specifiy all needed headers to say "do no ever use cache". (see article) I know there are workarounds (like addind query strings to end of urls etc) but why do firefox act like that, if i say that an image do not have to be cached, why is the image still taken from cache when i try to re-insert it ? Plus, what cache is used for this ? (I guess it's the memory cache) Is this behavior the same for dynamic inclusion for example ? ANSWSER IS NO :) I just tested it and the same headers for a js script will make firefox redownload it each time you append the script to the DOM. PS: I know you're wondering WHY i need to do that (appending same image multiple times and force to redownload but this is the way our app works) thank you The good answer is : firefox will store images for the current page load in the memory cache even if you specify he doesnt have to cache them. You can't change this behavior but this is odd because it's not the same for javascript files for example Could someone explain or link to a document describing how firefox cache WORKS?

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  • Overhead of calling tiny functions from a tight inner loop? [C++]

    - by John
    Say you see a loop like this one: for(int i=0; i<thing.getParent().getObjectModel().getElements(SOME_TYPE).count(); ++i) { thing.getData().insert( thing.GetData().Count(), thing.getParent().getObjectModel().getElements(SOME_TYPE)[i].getName() ); } if this was Java I'd probably not think twice. But in performance-critical sections of C++, it makes me want to tinker with it... however I don't know if the compiler is smart enough to make it futile. This is a made up example but all it's doing is inserting strings into a container. Please don't assume any of these are STL types, think in general terms about the following: Is having a messy condition in the for loop going to get evaluated each time, or only once? If those get methods are simply returning references to member variables on the objects, will they be inlined away? Would you expect custom [] operators to get optimized at all? In other words is it worth the time (in performance only, not readability) to convert it to something like: ElementContainer &source = thing.getParent().getObjectModel().getElements(SOME_TYPE); int num = source.count(); Store &destination = thing.getData(); for(int i=0;i<num;++i) { destination.insert(thing.GetData().Count(), source[i].getName(); } Remember, this is a tight loop, called millions of times a second. What I wonder is if all this will shave a couple of cycles per loop or something more substantial? Yes I know the quote about "premature optimisation". And I know that profiling is important. But this is a more general question about modern compilers, Visual Studio in particular.

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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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  • New to J2EE; architecture suggestions for a service/daemon?

    - by Kate
    I am brand new to the J2EE world. As an exercise to try and familiarize myself with J2EE, I'm trying to create a tiered web-app, but I'm getting a little stuck on what the best way is to spin up a service in the background that does work. Paramters of the service: It must open and hold a socket connection and receive information from the connected server. There is a 1-to-1 correlation between a user and a new socket connection. So the idea is the user presses a button on the web-page, and somewhere on the server a socket connection is opened. For the remainder of the users session (or until the user presses some sort of disconnect button) the socket remains open and pushes received information to some sort of centralized store that servlets can query and return to the user via AJAX. Is there a J2EE type way to handle this situation? Naturally what I would think to do is to just write a Java application that listens on a port that the servlets can connect to and spawns new threads that open these sockets, but that seems very ad-hoc to me. (PS: I am also new to Stack Overflow, so forgive me if it takes me some time to figure the site out!)

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