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• Many users, many cpus, no delays. Good for cloud?

  - by Eric

  I wish to set up a CPU-intensive time-important query service for users on the internet. A usage scenario is described below. Is cloud computing the right way to go for such an implementation? If so, what cloud vendor(s) cater to this type of application? I ask specifically, in terms of: 1) pricing 2) latency resulting from: - slow CPUs, instance creations, JIT compiles, etc.. - internal management and communication of processes inside the cloud (e.g. a queuing process and a calculation process) - communication between cloud and end user 3) ease of deployment A usage scenario I am expecting is: - A typical user sends a query (XML of size around 1K) once every 30 seconds on average. - Each query requires a numerical computation of average time 0.2 sec and max time 1 sec on a 1 GHz Pentium. The computation requires no data other than the query itself and is performed by the same piece of code each time. - The delay a user experiences between sending a query and receiving a response should be on average no more than 2 seconds and in general no more than 5 seconds. - A background save to a DB of the response should occur (not time critical) - There can be up to 30000 simultaneous users - i.e., on average 1000 queries a second, each requiring an average 0.2 sec calculation, so that would necessitate around 200 CPUs. Currently I'm look at GAE Java (for quicker deployment and less IT hassle) and EC2 (Speed and price optimization) as options. Where can I learn more about the right way to set ups such a system? past threads, different blogs, books, etc.. BTW, if my terminology is wrong or confusing, please let me know. I'd greatly appreciate any help.

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• What is the fastest way to insert 100 000 records from one database to another?

  - by Pentium10

  I have a mobile application. My client has a large data set ~100.000 records. It's updated frequently. When we sync we need to copy from one database to another. I have attached the second database to the main, and run an insert into table select * from sync.table. This is extremely slow, it takes about 10 minutes I think. I noticed that the journal file gets increased step by step. How can I speed this up? EDITED 1 I have indexes off, and I have journal off. Using insert into table select * from sync.table it still takes 10 minutes. EDITED 2 If I run a query like select id,invitem,invid,cost from inventory where itemtype = 1 order by invitem limit 50 it takes 15-20 seconds. The table schema is: CREATE TABLE inventory ('id' INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, 'serverid' INTEGER NOT NULL DEFAULT 0, 'itemtype' INTEGER NOT NULL DEFAULT 0, 'invitem' VARCHAR, 'instock' FLOAT NOT NULL DEFAULT 0, 'cost' FLOAT NOT NULL DEFAULT 0, 'invid' VARCHAR, 'categoryid' INTEGER DEFAULT 0, 'pdacategoryid' INTEGER DEFAULT 0, 'notes' VARCHAR, 'threshold' INTEGER NOT NULL DEFAULT 0, 'ordered' INTEGER NOT NULL DEFAULT 0, 'supplier' VARCHAR, 'markup' FLOAT NOT NULL DEFAULT 0, 'taxfree' INTEGER NOT NULL DEFAULT 0, 'dirty' INTEGER NOT NULL DEFAULT 1, 'username' VARCHAR, 'version' INTEGER NOT NULL DEFAULT 15 ) Indexes are created like CREATE INDEX idx_inventory_categoryid ON inventory (pdacategoryid); CREATE INDEX idx_inventory_invitem ON inventory (invitem); CREATE INDEX idx_inventory_itemtype ON inventory (itemtype); I am wondering, the insert into ... select * from isn't the fastest built-in way to do massive data copy? EDITED 3 SQLite is serverless, so please stop voting a particular answer, because that is not the answer I'm sure.

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• .net remoting - Better solution to wait for a service to initialize ?

  - by CitizenInsane

  Context I have a client application (which i cannot modify, i.e. i only have the binary) that needs to run from time to time external commands that depends on a resource which is very long to initialize (about 20s). I thus decided to initialize this resource once for all in a "CommandServer.exe" application (single instance in the system tray) and let my client application call an intermediate "ExecuteCommand.exe" program that uses .net remoting to perform the operation on the server. The "ExecuteCommand.exe" is in charge for starting the server on first call and then leave it alive to speed up further commands. The service: public interface IMyService { void ExecuteCommand(string[] args); } The "CommandServer.exe" (using WindowsFormsApplicationBase for single instance management + user friendly splash screen during resource initializations): private void onStartupFirstInstance(object sender, StartupEventArgs e) { // Register communication channel channel = new TcpServerChannel("CommandServerChannel", 8234); ChannelServices.RegisterChannel(channel, false); // Register service var resource = veryLongToInitialize(); service = new MyServiceImpl(resource); RemotingServices.Marshal(service, "CommandServer"); // Create icon in system tray notifyIcon = new NotifyIcon(); ... } The intermediate "ExecuteCommand.exe": static void Main(string[] args) { startCommandServerIfRequired(); var channel = new TcpClientChannel(); ChannelServices.RegisterChannel(channel, false); var service = (IMyService)Activator.GetObject(typeof(IMyService), "tcp://localhost:8234/CommandServer"); service.RunCommand(args); } Problem As the server is very long to start (about 20s to initialize the required resources), the "ExecuteCommand.exe" fails on service.RunCommand(args) line because the server is yet not available. Question Is there a elegant way I can tune the delay before to receive "service not available" when calling service.RunCommand ? NB1: Currently I'm working around the issue by adding a mutex in server to indicate for complete initiliazation and have "ExecuteCommand.exe" to wait for this mutex before to call service.RunCommand. NB2: I have no background with .net remoting, nor WCF which is recommended replacer. (I chose .net remoting because this looked easier to set-up for this single shot issue in running external commands).

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• JQuery transition animation

  - by kk-dev11

  This program randomly selects two employees from a json-object Employees array, winnerPos is already defined. For better user experience I programmed these functions to change pictures one by one. The animation stops when the randomly selected person is shown on the screen. The slideThrough function will be triggered when the start button is pressed. function slideThrough() { counter = 0; start = true; clearInterval(picInterval); picInterval = setInterval(function () { changePicture(); }, 500); } function changePicture() { if (start) { if (counter > winnerPos) { setWinner(); start = false; killInterval(); } else { var employee = Employees[counter]; winnerPic.fadeOut(200, function () { this.src = 'img/' + employee.image; winnerName.html(employee.name); $(this).fadeIn(300); }); counter++; } } } The problem is the animation doesn't work smoothly. At first it works, but not perfect. The second time the transition happens in an irregular way, i.e. different speed and fadeIn/fadeOut differs from picture to picture. Could anyone help me to fine-tune the transition?

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• List all foreign key constraints that refer to a particular column in a specific table

  - by Sid

  I would like to see a list of all the tables and columns that refer (either directly or indirectly) a specific column in the 'main' table via a foreign key constraint that has the ON DELETE=CASCADE setting missing. The tricky part is that there would be an indirect relationships buried across up to 5 levels deep. (example: ... great-grandchild- FK3 = grandchild = FK2 = child = FK1 = main table). We need to dig up the leaf tables-columns, not just the very 1st level. The 'good' part about this is that execution speed isn't of concern, it'll be run on a backup copy of the production db to fix any relational issues for the future. I did SELECT * FROM sys.foreign_keys but that gives me the name of the constraint - not the names of the child-parent tables and the columns in the relationship (the juicy bits). Plus the previous designer used short, non-descriptive/random names for the FK constraints, unlike our practice below The way we're adding constraints into SQL Server: ALTER TABLE [dbo].[UserEmailPrefs] WITH CHECK ADD CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] FOREIGN KEY([UserId]) REFERENCES [dbo].[UserMasterTable] ([UserId]) ON DELETE CASCADE GO ALTER TABLE [dbo].[UserEmailPrefs] CHECK CONSTRAINT [FK_UserEmailPrefs_UserMasterTable_UserId] GO The comments in this SO question inpire this question.

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• HTML5: Rendering absolute images using canvas

  - by Mark

  I am experimenting with canvas as part of my HTML5 introduction. This constitutes as assignment work, but I am not asking for any help on the actual coursework at all. I am trying to write a rendering engine, but having no luck because once the image is drawn on canvas it looks very distorted, and not at the right dimensions of the image itself. I have made a animation engine that loads images into an array, and then iterates through them at a certain speed. This is not the problem, and I assume is not causing the issue as this was happening when I drawn an image to the canvas. I think this is natural behaviour for images to be scaled/skewed when the window is resized, so I conquered that by simply redrawing the whole thing once the window is resized. The images I am using are isometric, and drawn at a pixel level. Would this cause the distortion? It seems setting the dimensions on the drawImage() function are not working are all. I am using JavaScript for the manipulation and rendering of the canvas. I would normally try and work it out myself, but I do not have any time to ponder why because I have no idea why it is even scaling/skewing the image once it is drawn on the canvas. I cannot share the code for obvious reasons. I should also mention, the canvas's dimension is the total width of the viewport, as I am developing a game. My question is: Has anyone encountered this and how would I correct it? Thanks for your help.

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• Is there a faster way to access a property member of a class using reflection?

  - by Ross Goddard

  I am currently using the following code to access the property of an object using reflection: Dim propInfo As Reflection.PropertyInfo = myType.GetProperty(propName) Dim objValue As Object = propInfo.GetValue(myObject, Nothing) I am having some issues with the speed since this type of code is being called many times and is causing some slowdown. I have been looking into using Refelction.Emit or dynamic methods, but I am not sure exactly how to make use of them. Background Information: I am creating a list of a subset of the properties of the object, associating then with some meta information (such as if they can be loaded from the database or xml, if they are editable, can the user see them). This is for later consumption so we can write code such as : foreach prop as BaseWrapper in graphNode.NodeProperties prop.LoadFromDataRow(dr) next The application makes heavy use of having access to this list. The problem is that on the initial load of a project, a larger number of objects are being created that make use of this, so for each object created it is looping through this code a number of times. I initially tried adding each property to the list manually, but this ran into problems with not everything being initialized at the correct time and some other issues. If there is no other good way, then I may have to rethink some of the design and see what else can be done to improve the performance.

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• multi-threading in MFC

  - by kiddo

  Hello all,in my application there is a small part of function,in which it will read files to get some information,the number of filecount would be utleast 50,So I thought of implementing threading.Say if the user is giving 50 files,I wanted to separate it as 5 *10, 5 thread should be created,so that each thread can handle 10 files which can speed up the process.And also from the below code you can see that some variables are common.I read some articles about threading and I am aware that only one thread should access a variable/contorl at a me(CCriticalStiuation can be used for that).For me as a beginner,I am finding hard to imlplement what I have learned about threading.Somebody please give me some idea with code shown below..thanks in advance file read function:// void CMyClass::GetWorkFilesInfo(CStringArray& dataFilesArray,CString* dataFilesB, int* check,DWORD noOfFiles,LPWSTR path) { CString cFilePath; int cIndex =0; int exceptionInd = 0; wchar_t** filesForWork = new wchar_t*[noOfFiles]; int tempCheck; int localIndex =0; for(int index = 0;index < noOfFiles; index++) { tempCheck = *(check + index); if(tempCheck == NOCHECKBOX) { *(filesForWork+cIndex) = new TCHAR[MAX_PATH]; wcscpy(*(filesForWork+cIndex),*(dataFilesB +index)); cIndex++; } else//CHECKED or UNCHECKED { dataFilesArray.Add(*(dataFilesB+index)); *(check + localIndex) = *(check + index); localIndex++; } } WorkFiles(&cFilePath,dataFilesArray,filesForWork, path, cIndex); dataFilesArray.Add(cFilePath); *(check + localIndex) = CHECKED; }

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• Design for fastest page download

  - by mexxican

  I have a file with millions of URLs/IPs and have to write a program to download the pages really fast. The connection rate should be at least 6000/s and file download speed at least 2000 with avg. 15kb file size. The network bandwidth is 1 Gbps. My approach so far has been: Creating 600 socket threads with each having 60 sockets and using WSAEventSelect to wait for data to read. As soon as a file download is complete, add that memory address(of the downloaded file) to a pipeline( a simple vector ) and fire another request. When the total download is more than 50Mb among all socket threads, write all the files downloaded to the disk and free the memory. So far, this approach has been not very successful with the rate at which I could hit not shooting beyond 2900 connections/s and downloaded data rate even less. Can somebody suggest an alternative approach which could give me better stats. Also I am working windows server 2008 machine with 8 Gig of memory. Also, do we need to hack the kernel so as we could use more threads and memory. Currently I can create a max. of 1500 threads and memory usage not going beyond 2 gigs [ which technically should be much more as this is a 64-bit machine ]. And IOCP is out of question as I have no experience in that so far and have to fix this application today. Thanks Guys!

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• C++ and its type system: How to deal with data with multiple types?

  - by sub

  "Introduction" I'm relatively new to C++. I went through all the basic stuff and managed to build 2-3 simple interpreters for my programming languages. The first thing that gave and still gives me a headache: Implementing the type system of my language in C++ Think of that: Ruby, Python, PHP and Co. have a lot of built-in types which obviously are implemented in C. So what I first tried was to make it possible to give a value in my language three possible types: Int, String and Nil. I came up with this: enum ValueType { Int, String, Nil }; class Value { public: ValueType type; int intVal; string stringVal; }; Yeah, wow, I know. It was extremely slow to pass this class around as the string allocator had to be called all the time. Next time I've tried something similar to this: enum ValueType { Int, String, Nil }; extern string stringTable[255]; class Value { public: ValueType type; int index; }; I would store all strings in stringTable and write their position to index. If the type of Value was Int, I just stored the integer in index, it wouldn't make sense at all using an int index to access another int, or? Anyways, the above gave me a headache too. After some time, accessing the string from the table here, referencing it there and copying it over there grew over my head - I lost control. I had to put the interpreter draft down. Now: Okay, so C and C++ are statically typed. How do the main implementations of the languages mentioned above handle the different types in their programs (fixnums, bignums, nums, strings, arrays, resources,...)? What should I do to get maximum speed with many different available types? How do the solutions compare to my simplified versions above?

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• Java JRE vs GCJ

  - by Martijn Courteaux

  Hi, I have this results from a speed test I wrote in Java: Java real 0m20.626s user 0m20.257s sys 0m0.244s GCJ real 3m10.567s user 3m5.168s sys 0m0.676s So, what is the but of GCJ then? With this results I'm sure I'm not going to compile it with GCJ! I tested this on Linux, are the results in Windows maybe better than that? This was the code from the application: public static void main(String[] args) { String str = ""; System.out.println("Start!!!"); for (long i = 0; i < 5000000L; i++) { Math.sqrt((double) i); Math.pow((double) i, 2.56); long j = i * 745L; String string = new String(String.valueOf(i)); string = string.concat(" kaka pipi"); // "Kaka pipi" is a kind of childly call in Dutch. string = new String(string.toUpperCase()); if (i % 300 == 0) { str = ""; } else { str += Long.toHexString(i); } } System.out.println("Stop!!!"); }

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• Faster way to convert from a String to generic type T when T is a valuetype?

  - by Kumba

  Does anyone know of a fast way in VB to go from a string to a generic type T constrained to a valuetype (Of T as Structure), when I know that T will always be some number type? This is too slow for my taste: Return DirectCast(Convert.ChangeType(myStr, GetType(T)), T) But it seems to be the only sane method of getting from a String -- T. I've tried using Reflector to see how Convert.ChangeType works, and while I can convert from the String to a given number type via a hacked-up version of that code, I have no idea how to jam that type back into T so it can be returned. I'll add that part of the speed penalty I'm seeing (in a timing loop) is because the return value is getting assigned to a Nullable(Of T) value. If I strongly-type my class for a specific number type (i.e., UInt16), then I can vastly increase the performance, but then the class would need to be duplicated for each numeric type that I use. It'd almost be nice if there was converter to/from T while working on it in a generic method/class. Maybe there is and I'm oblivious to its existence?

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• Help regarding multi-threading in MFC,please help me firends!

  - by kiddo

  Hello all,in my application there is a small part of function,in which it will read files to get some information,the number of filecount would be utleast 50,So I thought of implementing threading.Say if the user is giving 50 files,I wanted to separate it as 5 *10, 5 thread should be created,so that each thread can handle 10 files which can speed up the process.And also from the below code you can see that some variables are common.I read some articles about threading and I am aware that only one thread should access a variable/contorl at a me(CCriticalStiuation can be used for that).For me as a beginner,I am finding hard to imlplement what I have learned about threading.Somebody please give me some idea with code shown below..thanks in advance file read function:// void CMyClass::GetWorkFilesInfo(CStringArray& dataFilesArray,CString* dataFilesB, int* check,DWORD noOfFiles,LPWSTR path) { CString cFilePath; int cIndex =0; int exceptionInd = 0; wchar_t** filesForWork = new wchar_t*[noOfFiles]; int tempCheck; int localIndex =0; for(int index = 0;index < noOfFiles; index++) { tempCheck = *(check + index); if(tempCheck == NOCHECKBOX) { *(filesForWork+cIndex) = new TCHAR[MAX_PATH]; wcscpy(*(filesForWork+cIndex),*(dataFilesB +index)); cIndex++; } else//CHECKED or UNCHECKED { dataFilesArray.Add(*(dataFilesB+index)); *(check + localIndex) = *(check + index); localIndex++; } } WorkFiles(&cFilePath,dataFilesArray,filesForWork, path, cIndex); dataFilesArray.Add(cFilePath); *(check + localIndex) = CHECKED; }

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• Making firefox refresh images faster

  - by Earlz

  I have a thing I'm doing where I need a webpage to stream a series of images from the local client computer. I have a very simple run here: http://jsbin.com/idowi/34 The code is extremely simple setTimeout ( "refreshImage()", 100 ); function refreshImage(){ var date = new Date() var ticks = date.getTime() $('#image').attr('src','http://127.0.0.1:2723/signature?'+ticks.toString()); setTimeout ("refreshImage()", 100 ); } Basically I have a signature pad being used on the client machine. We want for the signature to show up in the web page and for them to see themselves signing it within the web page(the pad does not have an LCD to show it to them right there). So I setup a simple local HTTP server which grabs an image of what the current state of the signature pad looks like and it gets sent to the browser. This has no problems in any browser(tested in IE7, 8, and Chrome) but Firefox where it is extremely laggy and jumpy and doesn't keep with the 10 FPS rate. Does anyone have any ideas on how to fix this? I've tried creating very simple double buffering in javascript but that just made things worse. Also for a bit more information it seems that Firefox is executing the javascript at the correct framerate as on the server the requests are coming in at a constant speed. But the images are only refreshed inconsistently ranging from 5 times per second all the way down to 0 times per second(taking 2 seconds to do a refresh) Also I have tried using different image formats all with the same results. The formats I've tried include bitmaps, PNGs, and GIFs (GIFs caused a minor problem in Chrome with flicker though) Could it be possible that Firefox is somehow caching my images causing a slight lag? I send these headers though: Pragma-directive: no-cache Cache-directive: no-cache Cache-control: no-cache Pragma: no-cache Expires: 0

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• Looking for a good C++/.net book

  - by Michael Minerva

  I have recently started to feel that I need to greatly improve my C++ skills especially in the realm of .net. I graduated from a good four year university with a degree in computer science about 9 months ago and I have since been doing full time contract work for a small software company in my local area. Most of my work has been done using Java/lisp/cocoa/XML and before that most of my programming in my senior year was in java/C#. I did a decent amount of C++ in my Sophomore year and in my free time before that but I feel that my general knowledge of C++/.net is very lacking for the opportunities that are now coming my way. Can anyone recommend a good book that could help me get up too speed? I feel I do not need a very basic introduction to C++ but something that covers the fundamentals of .net would be good for me. So basically what I need is a book or books that would be good for a .net novice and a C++ developer who is just beyond novice. Also, a book that would help bein an interview by giving me a conversional understanding of C++ would be great. Thanks a lot!.

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• What is the best (Windows) program launcher?

  - by AR

  One of the biggest general productivity boosters I've used is a good program launcher. I was a long-time user of SlickRun, and I've tried a few others. My current favorite is Executor - by far the best I've used. Other options: Executor: My current favorite Vista Start Menu: Pretty good, actually, but Executor is similar (binds to Win+Z) and much more flexible. Quicksilver: For Macs only, but it seems to be the gold standard against which most other launchers are measured. Google Desktop: Press Ctrl+Ctrl and it's a quick launcher! AutoHotKey: Much,much more than just a launcher - more than I need, really. SlickRun: simple and unobtrusive Launchy: Seems to be the launcher of choice for many StackOverflow users :) Colibri: "Type Ahead - Information at the tip of your wings". Quite a cool concept. Many, many others. Scott Hanselman outlines some more here. I realize that everyone will have their own preferences, but the question is: is there anything that really stands out in terms of speed, features, and especially productivity increase?

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• PHP include taking too long

  - by wxiiir

  I have a php file with around 100mb which is full of arrays (only arrays). I've made a script that includes this file (for processing), first it exhausted the default Xampp 128mb memory limit, i've raised it to 1024mb but it just takes forever and doesn't do anything. I'm sure the problem is being created by the sheer size of the file because i've tried removing all lines of code and just leaving the include and an echo for me to know when it finishes executing, and it does the same thing (which is taking forever), i've also tried to run the 100mb file in separate and same thing again. A 10mb file is taking forever as well but a similar 1mb file is almost instantly read and executed so the problem must be more than just the file size. I was avoiding using c++ for a simple project as this and would rather not to as php is easier for me and the task that will be executed doesn't need to benefit from the added speed that it would have if it had been done in c++ but if i have no luck in solving this problem i guess i'll have to. EDIT Reasons for not using a database: 1-Whoever made it didn't used a database and it will be pretty hard to store this in an organized database if i'm not able to do something with it first, like just reading it, copying parts from it or putting in memory or something. 2-I don't have experience working with databases as pretty much all stuff i've ever done in php didn't needed large amounts of stored data, 50kb at best, if i was thinking about a big project or huge chunks of data as this one, i definitely would, but i didn't made this mess to start with and now i have to undo it. 3-The logic for having to store a small portion of data like 10mb in hard drive when now every computer has pretty much enough ram to fit the whole OS in it is pretty much incomprehensible unless someone gives a good explanation about it, if i had to access a lot of said files simultaneously i would understand but like i said, this is a simple project, this is the only file that will be accessed at a given time this isn't even to make some kind of website, it's to run a few times and be done with it.

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• Organizing development teams

  - by Patrick

  A long time ago, when my company was much smaller, dividing the development work over teams was quite easy: the 'application' team developed the applications-specific logic, often requiring a deep insight of specific industry problems) the 'generic' team developed the parts that were common/generic for all applications (user interface related stuff, database access, low-level Windows stuff, ...) Over the years the boundaries between the teams have become fuzzy: the 'application' teams often write application-specific functionality with a 'generic' part, so instead of asking the 'generic' team to write that part for them, they write it themselves to speed up the developments; then donate it to the 'generic' team the 'generic' team's focus seems to be more 'maintenance oriented'. All of the 'very generic' code has already been written, so no new developments are needed in it, but instead they continuously have to support all the functionality donated by the application teams. All this seems to indicate that it's not a good idea anymore to have this split in teams. Maybe the 'generic' team should evolve into a 'software quality' team (defining and guarding the rules for writing good quality software), or into a 'software deployment' team (defining how software should be deployed, installed, ...). How do you split up the work in different teams if you have different applications? everybody can write generic code and donates it to a central 'generic' team? everybody can write generic code, but nobody 'manages' this generic code (everybody is the owner) generic code is written by a 'generic' team only and the applications have to wait until the 'generic' team delivers the generic part (via a library, via a DLL) there is no overlap in code between the different applications some other way? Notice that thee advantage of having the mix (allowing everybody to write everywhere in the code) is that: code is written in a more flexible way it's easier to debug the code since you can easily step into the 'generic' code in the debugger But the big (and maybe only) disadvantage is that this generic code may become nobody's responsibility if there is no clear team that manages it anymore. What is your vision?

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• How does git fetches commits associated to a file ?

  - by liadan

  I'm writing a simple parser of .git/* files. I covered almost everything, like objects, refs, pack files etc. But I have a problem. Let's say I have a big 300M repository (in a pack file) and I want to find out all the commits which changed /some/deep/inside/file file. What I'm doing now is: fetching last commit finding a file in it by: fetching parent tree finding out a tree inside recursively repeat until I get into the file additionally I'm checking hashes of each subfolders on my way to file. If one of them is the same as in commit before, I assume that file was not changed (because it's parent dir didn't change) then I store the hash of a file and fetch parent commit finding file again and check if hash change occurs if yes then original commit (i.e. one before parent) was changing a file And I repeat it over and over until I reach very first commit. This solution works, but it sucks. In worse case scenario, first search can take even 3 minutes (for 300M pack). Is there any way to speed it up ? I tried to avoid putting so large objects in memory, but right now I don't see any other way. And even that, initial memory load will take forever :( Greets and thanks for any help!

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• jQuery trigger custom event synchronously?

  - by Miguel Angelo

  I am using the jQuery trigger method to call an event... but it behaves inconsistently. Sometimes it call the event, sometimes it does not. <a href="#" onclick=" $(this).trigger('custom-event'); window.location.href = 'url'; return false; ">text</a> The custom-event has lots of listeners added to it. It is as if the trigger method is not synchronous, allowing the window.location.href be changed before executing the events. And when window.location.href is changed a navigation occurs, interrupting everything. How can I trigger events synchronously? Using jQuery 1.8.1. Thanks! EDIT I have found that the event, when called has a stack trace like this: jQuery.fx.tick (jquery-1.8.1.js:9021) tick (jquery-1.8.1.js:8499) jQuery.Callbacks.self.fireWith (jquery-1.8.1.js:1082) jQuery.Callbacks.fire (jquery-1.8.1.js:974) jQuery.speed.opt.complete (jquery-1.8.1.js:8991) $.customEvent (myfile.js:28) This proves that jQuery trigger method is asynchronous. Oohhh my... =\

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• How do I slow down a flash game?

  - by dsaccount1

  Basically the objective is to click on certain targets, which upon doing so would destroy the target and garner you points. I've written a macro to help me until the point where its impossible to even see the target more than a mere flicker, (maybe even less than that, i cant see it with my eyes). But its possible because i believe others have done so. (Maybe on slower comps?) Anyway the question is, how would it be possible to slow down the flash game? I've thought of a couple of ways that could work but i'm not sure how to implement them. 1. Slow down the cpu speed? (smth like that? how?) 2. As the game progress the time the targets appear and stay up is reduced. Maybe theres a variable controlling all of this, isit possible to modify the address of this variable? freeze it or smth? Any ideas, suggestions and especially advice would really be appreciated, thanks!

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• Speeding up a group by date query on a big table in postgres

  - by zaius

  I've got a table with around 20 million rows. For arguments sake, lets say there are two columns in the table - an id and a timestamp. I'm trying to get a count of the number of items per day. Here's what I have at the moment. SELECT DATE(timestamp) AS day, COUNT(*) FROM actions WHERE DATE(timestamp) >= '20100101' AND DATE(timestamp) < '20110101' GROUP BY day; Without any indices, this takes about a 30s to run on my machine. Here's the explain analyze output: GroupAggregate (cost=675462.78..676813.42 rows=46532 width=8) (actual time=24467.404..32417.643 rows=346 loops=1) -> Sort (cost=675462.78..675680.34 rows=87021 width=8) (actual time=24466.730..29071.438 rows=17321121 loops=1) Sort Key: (date("timestamp")) Sort Method: external merge Disk: 372496kB -> Seq Scan on actions (cost=0.00..667133.11 rows=87021 width=8) (actual time=1.981..12368.186 rows=17321121 loops=1) Filter: ((date("timestamp") >= '2010-01-01'::date) AND (date("timestamp") < '2011-01-01'::date)) Total runtime: 32447.762 ms Since I'm seeing a sequential scan, I tried to index on the date aggregate CREATE INDEX ON actions (DATE(timestamp)); Which cuts the speed by about 50%. HashAggregate (cost=796710.64..796716.19 rows=370 width=8) (actual time=17038.503..17038.590 rows=346 loops=1) -> Seq Scan on actions (cost=0.00..710202.27 rows=17301674 width=8) (actual time=1.745..12080.877 rows=17321121 loops=1) Filter: ((date("timestamp") >= '2010-01-01'::date) AND (date("timestamp") < '2011-01-01'::date)) Total runtime: 17038.663 ms I'm new to this whole query-optimization business, and I have no idea what to do next. Any clues how I could get this query running faster?

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• php / phpDoc - @return instance of $this class ?

  - by searbe

  How do I mark a method as "returns an instance of the current class" in my phpDoc? In the following example my IDE (Netbeans) will see that setSomething always returns a foo object. But that's not true if I extent the object - it'll return $this, which in the second example is a bar object not a foo object. class foo { protected $_value = null; /** * Set something * * @param string $value the value * @return foo */ public function setSomething($value) { $this->_value = $value; return $this; } } $foo = new foo(); $out = $foo->setSomething(); So fine - setSomething returns a foo - but in the following example, it returns a bar..: class bar extends foo { public function someOtherMethod(){} } $bar = new bar(); $out = $bar->setSomething(); $out->someOtherMethod(); // <-- Here, Netbeans will think $out // is a foo, so doesn't see this other // method in $out's code-completion ... it'd be great to solve this as for me, code completion is a massive speed-boost. Anyone got a clever trick, or even better, a proper way to document this with phpDoc?

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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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• Good C++ array class for dealing with large arrays of data in a fast and memory efficient way?

  - by Shane MacLaughlin

  Following on from a previous question relating to heap usage restrictions, I'm looking for a good standard C++ class for dealing with big arrays of data in a way that is both memory efficient and speed efficient. I had been allocating the array using a single malloc/HealAlloc but after multiple trys using various calls, keep falling foul of heap fragmentation. So the conclusion I've come to, other than porting to 64 bit, is to use a mechanism that allows me to have a large array spanning multiple smaller memory fragments. I don't want an alloc per element as that is very memory inefficient, so the plan is to write a class that overrides the [] operator and select an appropriate element based on the index. Is there already a decent class out there to do this, or am I better off rolling my own? From my understanding, and some googling, a 32 bit Windows process should theoretically be able address up to 2GB. Now assuming I've 2GB installed, and various other processes and services are hogging about 400MB, how much usable memory do you think my program can reasonably expect to get from the heap? I'm currently using various flavours of Visual C++.

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