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• Concatenating string with number in Javascript

  - by Sparky

  I'm trying to create a simple calculator in Javascript. I have an array named expression chunk[0] = 12 chunk[1] = + (the "+" sign) chunk[1] = 5 I used a for loop to loop through the chunks (chunk[]) and join then into a single expression as follows:- equation = ""; // To make var equation a string for(i = 0; i <= length; i++) { equation = equation + expression[i]; alert(expression[i]); } alert(equation); alert(expression[i]) showed values 12, + and 5. But alert(equation) showed 125 (instead of "12+5"). I need the variable equation to be "12+5" so that I can later call eval(equation) and get the value of 12+5. What am I doing wrong here?

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• Improve disk read performance (multiple files) with threading

  - by pablo

  I need to find a method to read a big number of small files (about 300k files) as fast as possible. Reading them sequentially using FileStream and reading the entire file in a single call takes between 170 and 208 seconds (you know, you re-run, disk cache plays its role and time varies). Then I tried using PInvoke with CreateFile/ReadFile and using FILE_FLAG_SEQUENTIAL_SCAN, but I didn't appreciate any changes. I tried with several threads (divide the big set in chunks and have every thread reading its part) and this way I was able to improve speed just a little bit (not even a 5% with every new thread up to 4). Any ideas on how to find the most effective way to do this?

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• Is it better to store user text (such as a blog entry or private messages) in the database or as flat files?

  - by Fredashay

  I'm building a social networking type site that will be storing large chunks of text that's entered by users, such as blog entries and private messages. As such, these will be entered once, with minimal revisions, but many reads by multiple users over time. I'm using MySQL, by the way. My concerns are: Storing large blocks of text on the database will fill the database to capacity eventually. I read somewhere that storing user text in flat files is a security risk? (The filenames will be generated dynamically by the PHP, not by the user.) Storing them as text files may cause them to become out of sync if I ever have to reinitialize the database and restore it from backups. What are all your thoughts and advice, pros and cons?

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• I want to make my own Malloc

  - by Unknown

  I want to make my own malloc/free so I can make a precise copying allocator. Any gurus have any tips and suggestions? I have a few questions for now: Should I just malloc large chunks of memory, and then distribute from that so I don't have to call the system calls? How are copying collectors usually done? I would imagine that this part is a bit complicated to do efficiently. My naive implementation would just malloc a block the size of the remaining objects which would require 2x the space.

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• executorservice to read data from database in chuncks and run process on them

  - by TazMan

  I'm trying to write a process that would read data from a database and upload it onto a cloud datastore. How can I decide the partition strategy of the data? I want to query the table in chunks and process each chunk in 10 threads. Each thread basically will send the data to an individual node on a 10 node cluster on the cloud.. Where in the below multi threading code will the dataquery to extract and send 10 concurrent requests for uploading data to cloud would be? public class Caller { public static void main(String[] args) { ExecutorService executor = Executors.newFixedThreadPool(10); for (int i = 0; i < 10; i++) { Runnable worker = new DomainCDCProcessor(i); executor.execute(worker); } executor.shutdown(); while (!executor.isTerminated()) { } System.out.println("Finished all threads"); } }

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• Allocate from buffer in C

  - by Grimless

  I am building a simple particle system and want to use a single array buffer of structs to manage my particles. That said, I can't find a C function that allows me to malloc() and free() from an arbitrary buffer. Here is some pseudocode to show my intent: Particle* particles = (Particle*) malloc( sizeof(Particle) * numParticles ); Particle* firstParticle = <buffer_alloc>( particles ); initialize_particle( firstParticle ); // ... Some more stuff if (firstParticle->life < 0) <buffer_free>( firstParticle ); // @ program's end free(particles); Where <buffer_alloc> and <buffer_free> are functions that allocate and free memory chunks from arbitrary pointers (possibly with additional metadata such as buffer length, etc.). Do such functions exist and/or is there a better way to do this? Thank you!

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• Oracle anuncia resultados de Q3 FY10

  - by Paulo Folgado

  Oracle Reports GAAP EPS of $0.23, Non-GAAP EPS of $0.38New Software Licenses Up 13%, Applications New Licenses Up 21%Oracle Corporation today announced fiscal 2010 Q3 GAAP total revenues were up 17% to $6.4 billion, while non-GAAP total revenues were up 18% to $6.5 billion. Excluding the impact of Sun Microsystems, Inc., which Oracle acquired on January 26, 2010, GAAP total revenue grew 7%. GAAP new software license revenues were up 13% to $1.7 billion, and up 10% to $1.7 billion excluding Sun. GAAP software license updates and product support revenues were up 13% to $3.3 billion, while non-GAAP software license updates and product support revenues were up 12% to $3.3 billion. GAAP operating income was down 5% to $1.8 billion, and GAAP operating margin was 29%. Non-GAAP operating income was up 13% to $2.9 billion, and non-GAAP operating margin was 45%. GAAP net income was down 10% to $1.2 billion, while non-GAAP net income was up 9% to $1.9 billion. GAAP earnings per share were $0.23, down 11% compared to last year while non-GAAP earnings per share were up 9% to $0.38. GAAP operating cash flow on a trailing twelve-month basis was $8.2 billion. "Our solid top line growth, coupled with disciplined expense management, was key in generating $8.0 billion of free cash flow over the last twelve months," said Oracle CFO Jeff Epstein."The Sun integration is going even better than we expected," said Oracle President, Safra Catz. "We believe that Sun will make a significant contribution to our fourth quarter earnings per share as well as meet the profitability goals we set for next year.""Exadata is the fastest growing product in Oracle's history," said Oracle President, Charles Phillips. "Introduced a little over a year ago, the Exadata pipeline is now approaching $400 million with Q4 bookings forecast at nearly $100 million. This strengthens both sales growth and profitability in our Sun server and storage businesses.""Every quarter we grab huge chunks of market share from SAP," said Oracle CEO, Larry Ellison. "SAP's most recent quarter was the best quarter of their year, only down 15%, while Oracle's application sales were up 21%. But SAP is well ahead of us in the number of CEOs for this year, announcing their third and fourth, while we only had one."In addition, Oracle's Board of Directors declared a cash dividend of $0.05 per share of outstanding common stock to be paid to stockholders of record as of the close of business on April 14, 2010, with a payment date of May 5, 2010. Future declarations of quarterly dividends and the establishment of future record and payment dates are subject to the final determination of Oracle's Board of Directors.Q3 Earnings Conference Call and WebcastOracle will hold a conference call and web broadcast today to discuss these results at 2:00 p.m. Pacific. You may listen to the call by dialing (800) 214-0694 or (719) 955-1425, Passcode: 567035. To access the live Web broadcast of this event, please visit the Oracle Investor Relations Web site at http://www.oracle.com/investor.

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• Chunking a List - .NET vs Python

  - by Abhijeet Patel

  Chunking a List As I mentioned last time, I'm knee deep in python these days. I come from a statically typed background so it's definitely a mental adjustment. List comprehensions is BIG in Python and having worked with a few of them I can see why. Let's say we need to chunk a list into sublists of a specified size. Here is how we'd do it in C#  static class Extensions   {       public static IEnumerable<List<T>> Chunk<T>(this List<T> l, int chunkSize)       {           if (chunkSize <0)           {               throw new ArgumentException("chunkSize cannot be negative", "chunkSize");           }           for (int i = 0; i < l.Count; i += chunkSize)           {               yield return new List<T>(l.Skip(i).Take(chunkSize));           }       }    }    static void Main(string[] args)  {           var l = new List<string> { "a", "b", "c", "d", "e", "f","g" };             foreach (var list in l.Chunk(7))           {               string str = list.Aggregate((s1, s2) => s1 + "," + s2);               Console.WriteLine(str);           }   }   A little wordy but still pretty concise thanks to LINQ.We skip the iteration number plus chunkSize elements and yield out a new List of chunkSize elements on each iteration. The python implementation is a bit more terse. def chunkIterable(iter, chunkSize):      '''Chunks an iterable         object into a list of the specified chunkSize     '''        assert hasattr(iter, "__iter__"), "iter is not an iterable"      for i in xrange(0, len(iter), chunkSize):          yield iter[i:i + chunkSize]    if __name__ == '__main__':      l = ['a', 'b', 'c', 'd', 'e', 'f']      generator = chunkIterable(l,2)      try:          while(1):              print generator.next()      except StopIteration:          pass   xrange generates elements in the specified range taking in a seed and returning a generator. which can be used in a for loop(much like using a C# iterator in a foreach loop) Since chunkIterable has a yield statement, it turns this method into a generator as well. iter[i:i + chunkSize] essentially slices the list based on the current iteration index and chunksize and creates a new list that we yield out to the caller one at a time. A generator much like an iterator is a state machine and each subsequent call to it remembers the state at which the last call left off and resumes execution from that point. The caveat to keep in mind is that since variables are not explicitly typed we need to ensure that the object passed in is iterable using hasattr(iter, "__iter__").This way we can perform chunking on any object which is an "iterable", very similar to accepting an IEnumerable in the .NET land

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• How should I pitch moving to an agile/iterative development cycle with mandated 3-week deployments?

  - by Wayne M

  I'm part of a small team of four, and I'm the unofficial team lead (I'm lead in all but title, basically). We've largely been a "cowboy" environment, with no architecture or structure and everyone doing their own thing. Previously, our production deployments would be every few months without being on a set schedule, as things were added/removed to the task list of each developer. Recently, our CIO (semi-technical but not really a programmer) decided we will do deployments every three weeks; because of this I instantly thought that adopting an iterative development process (not necessarily full-blown Agile/XP, which would be a huge thing to convince everyone else to do) would go a long way towards helping manage expectations properly so there isn't this far-fetched idea that any new feature will be done in three weeks. IMO the biggest hurdle is that we don't have ANY kind of development approach in place right now (among other things like no CI or automated tests whatsoever). We don't even use Waterfall, we use "Tell Developer X to do a task, expect him to do everything and get it done". Are there any pointers that would help me start to ease us towards an iterative approach and A) Get the other developers on board with it and B) Get management to understand how iterative works? So far my idea involves trying to set up a CI server and get our build process automated (it takes about 10-20 minutes right now to simply build the application to put it on our development server), since pushing tests and/or TDD will be met with a LOT of resistance at this point, and constantly force us to break larger projects into smaller chunks that could be done iteratively in a three-week cycle; my only concern is that, unless I'm misunderstanding, an agile/iterative process may or may not release the software (depending on the project scope you might have "working" software after three weeks, but there isn't enough of it that works to let users make use of it), while I think the expectation here from management is that there will always be something "ready to go" in three weeks, and that disconnect could cause problems. On that note, is there any literature or references that explains the agile/iterative approach from a business standpoint? Everything I've seen only focuses on the developers, how to do it, but nothing seems to describe it from the perspective of actually getting the buy-in from the businesspeople.

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• How can story and gameplay be artfully merged?

  - by NauticalMile

  Let me give some context. Three of my friends and I have a pretty good game idea cooking. It's based off of a prototype I made that's evolving into a cool game mechanic. The mechanic itself is a toy that's fun on its own, but we haven't designed any puzzles around it yet. We have a design document going, and we are answering a lot of questions about what's in the game. It's become clear early on that everyone (including myself) likes the characters and the story a lot. Considering what our favorite games are, this is unsurprising. A story driven game makes sense to me. I like the emphasis that Paper Mario: The Thousand-Year-Door, Portal 2, and Tomb Raider place on story, and I imagine our game will have a similar feel (lots of dialogue, plot twists, lovable characters). However, one team member raised this point in the design doc: I am feeling like [fleshing out the story] is our biggest hurdle right now for making more design decisions - like more specific decisions about levels etc. Is this true? I am uncertain about working on the story extensively before gameplay, and my uneasiness was reinforced when I read this question about story vs. gameplay. What I want to say is: "Let's continue to work on the story, but also start brainstorming and prototyping abstract puzzles and combat sequences, and we'll creatively match them together later." Is this a reasonable approach? If so, how much of the development of these elements should be done independently? Should I try and create a whole bunch of puzzles while my other teammates focus on story and aesthetics? Then when we have a lot of story and game 'chunks' we can match them with eachother to build something meaningful. Or should we focus on iterating individual levels as distinct units where puzzles, story, etc... are designed together? Or maybe we need to put our excitement about the story on hold and just focus on gameplay. Is there another approach to design that we can take? Am I missing something crucial? I have discussed story and gameplay because they seem the most likely to be at odds with each other, but we also have to consider user interface, music, art direction, etc... Can we design these independently as well?

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• Producing a smooth mesh from density cloud and marching cubes

  - by Wardy

  Based on my results from this question I decided to build myself a 3D noise map containing float values in place of my existing boolean point values. The effect I'm trying to produce is something like this, rather than typical rolling hills; which should explain the "missing cubes" in the image below. If I render my density map in normal "minecraft mode" (1 block per point in the density map) varying the size of the cube based on the value in my density map (floats in the range 0 to 1) I get something like this: I'm now happy that I can produce a density map for the marching cubes algorithm (which will need a little tweaking) but for some reason when I run it through my implementation it's not producing what I expect. My problem is that I'm getting something like the first image in this answer to my previous question, when I want to achieve the effect in the second image. Upon further investigation I can't see how marching cubes does the "move vertex along the edge" type logic (i.e. the difference between the two images on my previous link). I see that it does do some interpolation, but I'm not convinced I have the correct understanding of what I think it should do, because the code in question appears to give the same result regardless of whether I use boolean or float values. I took the code from here which is a C# implementation of marching cubes, but instead of using the MarchingCubesPrimitive I modified it to accept an object of type IDrawable, containing lists for the various collections (vertices, normals, UVs, indices), the logic was otherwise untouched. My understanding is that given a very low isovalue the accuracy level of the surface being rendered should increase, so in short "less 45 degree slows more rolling hills" type mesh output. However this isn't what I'm seeing. Have I missed something or is the implementation flawed and need to be fixed? EDIT: A little more detail on what I am seeing when I "marching cube" the data. Ok so firstly, ignore the fact that the meshes created by the chunks don't "connect" (i'll probably raise another question about this later). Then look at the shaping of the island, it's too ... square, from the voxels rendered as boxes you get the impression there's a clean soft gradual hill and yet from the image there are sharp falling edges even in the most central areas where the gradient in the first image looks the most smooth. The data is "regenerated" each time I run this so no 2 islands come out the same, and it's purely random so not based on noise, but still, how can it look so smooth in 1 image and so not smooth in the other?

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• Dealing with coworkers when developing, need advice [closed]

  - by Yippie-Kai-Yay

  I developed our current project architecture and started developing it on my own (reaching something like, revision 40). We're developing a simple subway routing framework and my design seemed to be done extremely well - several main models, corresponding views, main logic and data structures were modeled "as they should be" and fully separated from rendering, algorithmic part was also implemented apart from the main models and had a minor number of intersection points. I would call that design scalable, customizable, easy-to-implement, interacting mostly based on the "black box interaction" and, well, very nice. Now, what was done: I started some implementations of the corresponding interfaces, ported some convenient libraries and wrote implementation stubs for some application parts. I had the document describing coding style and examples of that coding style usage (my own written code). I forced the usage of more or less modern C++ development techniques, including no-delete code (wrapped via smart pointers) and etc. I documented the purpose of concrete interface implementations and how they should be used. Unit tests (mostly, integration tests, because there wasn't a lot of "actual" code) and a set of mocks for all the core abstractions. I was absent for 12 days. What do we have now (the project was developed by 4 other members of the team): 3 different coding styles all over the project (I guess, two of them agreed to use the same style :), same applies to the naming of our abstractions (e.g CommonPathData.h, SubwaySchemeStructures.h), which are basically headers declaring some data structures. Absolute lack of documentation for the recently implemented parts. What I could recently call a single-purpose-abstraction now handles at least 2 different types of events, has tight coupling with other parts and so on. Half of the used interfaces now contain member variables (sic!). Raw pointer usage almost everywhere. Unit tests disabled, because "(Rev.57) They are unnecessary for this project". ... (that's probably not everything). Commit history shows that my design was interpreted as an overkill and people started combining it with personal bicycles and reimplemented wheels and then had problems integrating code chunks. Now - the project still does only a small amount of what it has to do, we have severe integration problems, I assume some memory leaks. Is there anything possible to do in this case? I do realize that all my efforts didn't have any benefit, but the deadline is pretty soon and we have to do something. Did someone have a similar situation? Basically I thought that a good (well, I did everything that I could) start for the project would probably lead to something nice, however, I understand that I'm wrong. Any advice would be appreciated, sorry for my bad english.

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• .Net Application & Database Modularity/Reuse

  - by Martaver

  I'm looking for some guidance on how to architect an app with regards to modularity, separation of concerns and re-usability. I'm working on an application (ASP.Net, C#) that has distinctly generic chunks of functionality, that I'd love to be able to lift out, all layers, into re-usable components. This means the module handles the database schema, data access, API, everything so that the next time I want to use it I can just register the module and hook into it. Developing modules of re-usable functionality is a no-brainer, but what is really confusing me is what to do when it comes to handling a core re-usable database schema that serves the module's functionality. In an ideal world, I would register a module and it would ensure that the associated database schema exists in the DB. I would code on the assumption that the tables exist, calling the module's functionality through the DLL, agnostic of the database layer. Kind of like Enterprise Library's Caching/Logging Application Block, which can create a DB schema in the target DB to use as a data store. My Questions is: What do you think is the best way to achieve this, firstly, in terms design architecture, and secondly solution structure. What patterns/frameworks do you know that exist & support this kind of thing? My thoughts so far: I mostly use Entity Framework and SQL Server DB Projects. I thought about a 'black box' approach to modules of functionality. I could use use a code-first approach in EF4, and use the ObjectContext to create a database when the module is initialized. However this means that all of the entities that my module encapsulates would be disconnected from the rest of the application because they belonged to an abstracted ObjectContext. Further - Creating appropriate indexes and references between domain entities and the module's entities would be impossible to do practically. I've thought of adopting Enterprise Library and creating my own Application Blocks. I'm not sure how this would play nice with Entity Framework (if at all) though. I like the idea of building on proven patterns & practices to encapsulate established, reusable functionality. I thought of abandoning Entity Framework for the Module, and just creating a separate DB schema for the module with its own set of stored procedures & ADO.Net. Then deploying the script at run-time if interrogation shows that it doesn't exist. But once again, for application developing outside of the application, I would want to use Entity Framework and I would have to use the module separately, disconnected from the domain ObjectContext. Has anyone had experience developing these sorts of full-stack modules? What advice can you offer? Am I biting off more than I can chew?

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• Data Virtualization: Federated and Hybrid

  - by Krishnamoorthy

  Data becomes useful when it can be leveraged at the right time. Not only enterprises application stores operate on large volume, velocity and variety of data. Mobile and social computing are in the need of operating in foresaid data. Replicating and transferring large swaths of data is one challenge faced in the field of data integration. However, smaller chunks of data aggregated from a variety of sources presents and even more interesting challenge in the industry. Over the past few decades, technology trends focused on best user experience, operating systems, high performance computing, high performance web sites, analysis of warehouse data, service oriented architecture, social computing, cloud computing, and big data. Operating on the ‘dark data’ becomes mandatory in the future technology trend, although, no solution can make dark data useful data in a single day. Useful data can be quantified by the facts of contextual, personalized and on time delivery. In most cases, data from a single source may not be complete the picture. Data has to be combined and computed from various sources, where data may be captured as hybrid data, meaning the combination of structured and unstructured data. Since related data is often found across disparate sources, effectively integrating these sources determines how useful this data ultimately becomes. Technology trends in 2013 are expected to focus on big data and private cloud. Consumers are not merely interested in where data is located or how data is retrieved and computed. Consumers are interested in how quick and how the data can be leveraged. In many cases, data virtualization is the right solution, and is expected to play a foundational role for SOA, Cloud integration, and Big Data. The Oracle Data Integration portfolio includes a data virtualization product called ODSI (Oracle Data Service Integrator). Unlike other data virtualization solutions, ODSI can perform both read and write operations on federated/hybrid data (RDBMS, Webservices,  delimited file and XML). The ODSI Engine is built on XQuery, hence ODSI user can perform computations on data either using XQuery or SQL. Built in data and query caching features, which reduces latency in repetitive calls. Rightly positioning ODSI, can results in a highly scalable model, reducing spend on additional hardware infrastructure.

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• Marshalling C# Structs into DX11 cbuffers

  - by Craig

  I'm having some issues with the packing of my structure in C# and passing them through to cbuffers I have registered in HLSL. When I pack my struct in one manner the information seems to be able to pass to the shader: [StructLayout(LayoutKind.Explicit, Size = 16)] internal struct TestStruct { [FieldOffset(0)] public Vector3 mEyePosition; [FieldOffset(12)] public int type; } This works perfectly when used against this HLSL fragment: cbuffer PerFrame : register(b0) { Vector3 eyePos; int type; } float3 GetColour() { float3 returnColour = float(0.0f, 0.0f, 0.0f); switch(type) { case 0: returnColour = float3(1.0f, 0.0f, 0.0f); break; case 1: returnColour = float3(0.0f, 1.0f, 0.0f); break; case 2: returnColour = float3(0.0f, 0.0f, 1.0f); break; } return returnColour; } However, when I use the following structure definitions... // Note this is 16 because HLSL packs in 4 float 'chunks'. // It is also simplified, but still demonstrates the problem. [StructLayout(Layout.Explicit, Size = 16)] internal struct InternalTestStruct { [FieldOffset(0)] public int type; } [StructLayout(LayoutKind.Explicit, Size = 32)] internal struct TestStruct { [FieldOffset(0)] public Vector3 mEyePosition; //Missing 4 bytes here for correct packing. [FieldOffset(16)] public InternalTestStruct mInternal; } ... the following HLSL fragment no longer works. struct InternalType { int type; } cbuffer PerFrame : register(b0) { Vector3 eyePos; InternalType internalStruct; } float3 GetColour() { float3 returnColour = float(0.0f, 0.0f, 0.0f); switch(internaltype.type) { case 0: returnColour = float3(1.0f, 0.0f, 0.0f); break; case 1: returnColour = float3(0.0f, 1.0f, 0.0f); break; case 2: returnColour = float3(0.0f, 0.0f, 1.0f); break; } return returnColour; } Is there a problem with the way I am packing the struct, or is it another issue? To re-iterate: I can pass a struct in a cbuffer so long as it does not contain a nested struct.

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• How do I randomly generate a top-down 2D level with separate sections and is infinite?

  - by Bagofsheep

  I've read many other questions/answers about random level generation but most of them deal with either randomly/proceduraly generating 2D levels viewed from the side or 3D levels. What I'm trying to achieve is sort of like you were looking straight down on a Minecraft map. There is no height, but the borders of each "biome" or "section" of the map are random and varied. I already have basic code that can generate a perfectly square level with the same tileset (randomly picking segments from the tileset image), but I've encountered a major issue for wanting the level to be infinite: Beyond a certain point, the tiles' positions become negative on one or both of the axis. The code I use to only draw tiles the player can see relies on taking the tiles position and converting it to the index number that represents it in the array. As you well know, arrays cannot have a negative index. Here is some of my code: This generates the square (or rectangle) of tiles: //Scale is in tiles public void Generate(int sX, int sY) { scaleX = sX; scaleY = sY; for (int y = 0; y <= scaleY; y++) { tiles.Add(new List<Tile>()); for (int x = 0; x <= scaleX; x++) { tiles[tiles.Count - 1].Add(tileset.randomTile(x * tileset.TileSize, y * tileset.TileSize)); } } } Before I changed the code after realizing an array index couldn't be negative my for loops looked something like this to center the map around (0, 0): for (int y = -scaleY / 2; y <= scaleY / 2; y++) for (int x = -scaleX / 2; x <= scaleX / 2; x++) Here is the code that draws the tiles: int startX = (int)Math.Floor((player.Position.X - (graphics.Viewport.Width) - tileset.TileSize) / tileset.TileSize); int endX = (int)Math.Ceiling((player.Position.X + (graphics.Viewport.Width) + tileset.TileSize) / tileset.TileSize); int startY = (int)Math.Floor((player.Position.Y - (graphics.Viewport.Height) - tileset.TileSize) / tileset.TileSize); int endY = (int)Math.Ceiling((player.Position.Y + (graphics.Viewport.Height) + tileset.TileSize) / tileset.TileSize); for (int y = startY; y < endY; y++) { for (int x = startX; x < endX; x++) { if (x >= 0 && y >= 0 && x <= scaleX && y <= scaleY) tiles[y][x].Draw(spriteBatch); } } So to summarize what I'm asking: First, how do I randomly generate a top-down 2D map with different sections (not chunks per se, but areas with different tile sets) and second, how do I get past this negative array index issue?

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• Does OO, TDD, and Refactoring to Smaller Functions affect Speed of Code?

  - by Dennis

  In Computer Science field, I have noticed a notable shift in thinking when it comes to programming. The advice as it stands now is write smaller, more testable code refactor existing code into smaller and smaller chunks of code until most of your methods/functions are just a few lines long write functions that only do one thing (which makes them smaller again) This is a change compared to the "old" or "bad" code practices where you have methods spanning 2500 lines, and big classes doing everything. My question is this: when it call comes down to machine code, to 1s and 0s, to assembly instructions, should I be at all concerned that my class-separated code with variety of small-to-tiny functions generates too much extra overhead? While I am not exactly familiar with how OO code and function calls are handled in ASM in the end, I do have some idea. I assume that each extra function call, object call, or include call (in some languages), generate an extra set of instructions, thereby increasing code's volume and adding various overhead, without adding actual "useful" code. I also imagine that good optimizations can be done to ASM before it is actually ran on the hardware, but that optimization can only do so much too. Hence, my question -- how much overhead (in space and speed) does well-separated code (split up across hundreds of files, classes, and methods) actually introduce compared to having "one big method that contains everything", due to this overhead? UPDATE for clarity: I am assuming that adding more and more functions and more and more objects and classes in a code will result in more and more parameter passing between smaller code pieces. It was said somewhere (quote TBD) that up to 70% of all code is made up of ASM's MOV instruction - loading CPU registers with proper variables, not the actual computation being done. In my case, you load up CPU's time with PUSH/POP instructions to provide linkage and parameter passing between various pieces of code. The smaller you make your pieces of code, the more overhead "linkage" is required. I am concerned that this linkage adds to software bloat and slow-down and I am wondering if I should be concerned about this, and how much, if any at all, because current and future generations of programmers who are building software for the next century, will have to live with and consume software built using these practices. UPDATE: Multiple files I am writing new code now that is slowly replacing old code. In particular I've noted that one of the old classes was a ~3000 line file (as mentioned earlier). Now it is becoming a set of 15-20 files located across various directories, including test files and not including PHP framework I am using to bind some things together. More files are coming as well. When it comes to disk I/O, loading multiple files is slower than loading one large file. Of course not all files are loaded, they are loaded as needed, and disk caching and memory caching options exist, and yet still I believe that loading multiple files takes more processing than loading a single file into memory. I am adding that to my concern.

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• Redesigning an Information System - Part 1

  - by dbradley

  Through the next few weeks or months I'd like to run a small series of articles sharing my experiences from the largest of the project I've worked on and explore some of the real-world problems I've come across and how we went about solving them. I'm afraid I can't give too many specifics on the project right now as it's not yet complete so you'll have to forgive me for being a little abstract in places! To start with I'm going to run through a little of the background of the problem and the motivations to re-design from scratch. Then I'll work through the approaches taken to understanding the requirements, designing, implementing, testing and migrating to the new system. Motivations for Re-designing a Large Information System The system is one that's been in place for a number of years and was originally designed to do a significantly different one to what it's now being used for. This is mainly due to the product maturing as well as client requirements changing. As with most information systems this one can be defined in four main areas of functionality: Input – adding information to the system Storage – persisting information in an efficient, searchable structure Output – delivering the information to the client Control – management of the process There can be a variety of reasons to re-design an existing system; a few of our own turned out to be factors such as: Overall system reliability System response time Failure isolation and recovery Maintainability of code and information General extensibility to solve future problem Separation of business and product concerns New or improved features The factor that started the thought process was the desire to improve the way in which information was entered into the system. However, this alone was not the entire reason for deciding to redesign. Business Drivers Typically all software engineers would always prefer to do a project from scratch themselves. It generally means you don't have to deal with problems created by predecessors and you can create your own absolutely perfect solution. However, the reality of working within a business is that the bottom line comes down to return on investment. For a medium sized business such as mine there must be actual value able to be delivered within a reasonable timeframe for any work to be started. As a result, any long term project will generally take a lot of effort and consideration to be approved by those in charge and therefore it might be better to break down the project into more manageable chunks which allow more frequent deliverables and also value within a shorter timeframe. As the only thing of concern was the methods for inputting information, this is where we started with requirements gathering and design. However knowing that there might be more to the problem and not limiting your design decisions before the requirements is key to finding the best solutions.

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• openGL textures in bitmap mode

  - by evenex_code

  For reasons detailed here I need to texture a quad using a bitmap (as in, 1 bit per pixel, not an 8-bit pixmap). Right now I have a bitmap stored in an on-device buffer, and am mounting it like so: glBindBuffer(GL_PIXEL_UNPACK_BUFFER, BFR.G[(T+1)%2]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, W, H, 0, GL_COLOR_INDEX, GL_BITMAP, 0); The OpenGL spec has this to say about glTexImage2D: "If type is GL_BITMAP, the data is considered as a string of unsigned bytes (and format must be GL_COLOR_INDEX). Each data byte is treated as eight 1-bit elements..." Judging by the spec, each bit in my buffer should correspond to a single pixel. However, the following experiments show that, for whatever reason, it doesn't work as advertised: 1) When I build my texture, I write to the buffer in 32-bit chunks. From the wording of the spec, it is reasonable to assume that writing 0x00000001 for each value would result in a texture with 1-px-wide vertical bars with 31-wide spaces between them. However, it appears blank. 2) Next, I write with 0x000000FF. By my apparently flawed understanding of the bitmap mode, I would expect that this should produce 8-wide bars with 24-wide spaces between them. Instead, it produces a white 1-px-wide bar. 3) 0x55555555 = 1010101010101010101010101010101, therefore writing this value ought to create 1-wide vertical stripes with 1 pixel spacing. However, it creates a solid gray color. 4) Using my original 8-bit pixmap in GL_BITMAP mode produces the correct animation. I have reached the conclusion that, even in GL_BITMAP mode, the texturer is still interpreting 8-bits as 1 element, despite what the spec seems to suggest. The fact that I can generate a gray color (while I was expecting that I was working in two-tone), as well as the fact that my original 8-bit pixmap generates the correct picture, support this conclusion. Questions: 1) Am I missing some kind of prerequisite call (perhaps for setting a stride length or pack alignment or something) that will signal to the texturer to treat each byte as 8-elements, as it suggests in the spec? 2) Or does it simply not work because modern hardware does not support it? (I have read that GL_BITMAP mode was deprecated in 3.3, I am however forcing a 3.0 context.) 3) Am I better off unpacking the bitmap into a pixmap using a shader? This is a far more roundabout solution than I was hoping for but I suppose there is no such thing as a free lunch.

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• Zelda-style top-down RPG. How to store tile and collision data?

  - by Delerat

  I'm looking to build a Zelda: LTTP style top-down RPG. I've read a lot on the subject and am currently going back and forth on a few solutions. I'm using C#, MonoGame, and Tiled. For my tile maps, these are the choices I can see in front of me: Store each tile as its own array. Each one having 3-4 layers, texture/animation, depth, flags, and maybe collision(depending on how I do it). I've read warning about memory issues going this route, and my biggest map will probably be 160x120 tiles. My average map however will be about 40x30. The number of tiles might cut in half if I decide to double my tile size, which is currently 16x16. This is the most appealing approach for me, as I feel like I would know how to save maps, make changes, and separate it into chunks for collision checks. Store the static parts of my tile map in multiple arrays acting as the different layers. Then I would just use entities for anything that wasn't static. All of the other tile data such as collisions, depth, etc., would be stored in their own layers as well I guess? This way just seems messy to me though. Regardless of which one I choose, I'm also unsure how to plan all of that other tile data. I could write a bunch of code that would know which integer represents what tile and it's data, but if I changed a tileset in Tiled and exported it again, all of those integers could potentially change and I'd have to adjust a whole bunch of code. My other issue is about how I could do collision. I want to at least support angled collision that slides you around the corners of objects like LTTP does, if not more oddball shapes as well. So do I: Store collision as a flag for binary collision. Could I get this to support angles? Would it be fine to store collision as an integer and have each number represent a certain angle of collision? Store a list of rectangles or other shapes and do collision that way? Sorry for the large two-part(three-part?) question. I felt like these needed to be asked together as I believe each choice influences the other.

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• Chunking large rsync transfers?

  - by Gabe Martin-Dempesy

  We use rsync to update a mirror of our primary file server to an off-site colocated backup server. One of the issues we currently have is that our file server has 1TB of mostly smaller files (in the 10-100kb range), and when we're transferring this much data, we often end up with the connection being dropped several hours into the transfer. Rsync doesn't have a resume/retry feature that simply reconnects to the server to pickup where it left off -- you need to go through the file comparison process, which ends up being very length with the amount of files we have. The solution that's recommended to get around is to split up your large rsync transfer into a series of smaller transfers. I've figured the best way to do this is by first letter of the top-level directory names, which doesn't give us a perfectly even distribution, but is good enough. I'd like to confirm if my methodology for doing this is sane, or if there's a more simple way to accomplish the goal. To do this, I iterate through A-Z, a-z, 0-9 to pick a one character $prefix. Initially I was thinking of just running rsync -av --delete --delete-excluded --exclude "*.mp3" "src/$prefix*" dest/ (--exclude "*.mp3" is just an example, as we have a more lengthy exclude list for removing things like temporary files) The problem with this is that any top-level directories in dest/ that are no longer present present on src will not get picked up by --delete. To get around this, I'm instead trying the following: rsync \ --filter 'S /$prefix*' \ --filter 'R /$prefix*' \ --filter 'H /*' \ --filter 'P /*' \ -av --delete --delete-excluded --exclude "*.mp3" src/ dest/ I'm using the show and hide over include and exclude, because otherwise the --delete-excluded will delete anything that doesn't match $prefix. Is this the most effective way of splitting the rsync into smaller chunks? Is there a more effective tool, or a flag that I've missed, that might make this more simple?

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• Excel VBA: select every other cell in a row range to be copied and pasted vertically

  - by terry alexander

  i have a 2200+ page text file. It is delivered from a customer through a data exchange to us with astericks to separate values and tildes (~) to denote the end of a row. The file is sent to me as a text file in Word. Most rows are split in two (1 row covers a full line and part of a second line). i transfer segments (10 page chunks) of it at a time into Excel where, unfortunately, any zeroes that occur at the end of a row get discarded in the "text to columns" procedure. So, i eyeball every "long" row to insure that zeroes were not lost and manually re-enter any that were. Here is a small bit of sample data: SDQ EA 92 1551 378 1601 151 1603 157 1604 83 The "SDQ, EA, and 92" are irrelevant (artifacts of data transmission). i want to use Excel VBA to select 1551, 1601, 1603, and 1604 (these are store numbers) so that i can copy those values and transpose paste them vertically. i will then go back and copy 378, 151, 157, and 83 (sales values) so that i can transpose paste them next to the store numbers. The next two rows of data contain the same store numbers but give the corresponding dollar values. i will only need to copy the dollar values so they can be transpose pasted vertically next to unit values (e.g. 378, 151, 157, and 83). Just being able to put my cursor on the first cell of interest in the row and run a macro to copy every other cell would speed up my work tremendously. i have tried using activecell and offset references to select a range to copy but have not been successful. Does any have any suggestions for me? Thanks in advance for the help.

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• Virtual Machines Renaming/Backing up/Sharing

  - by evan

  I've started using VMware virtual machines for all of my software development projects and have a few questions for others doing the same thing. First, how can you rename the virtual machine and the name of the virtual hard drive? I have a base development machine that I clone for different projects. I'd like to name the machine and it's hard drive according the the project (right now when I copy them via cut and paste, the file names remain the same and I can only organize them by putting them in a specific directory). Second, what is the best way to back up a virtual machine? Is it possible (by breaking the virtual hard drive up into chunks instead of one big file) to get incremental backups working? It seems time machine always tries to make a copy of the whole thing which is time consuming because each virtual machine is around 30GB. Finally, how slow would it be to have a virtual machine shared on an NFS mount on a wireless N network and used from multiple computers (but with only one person using it at a time.) Would it be more reasonable on a gigabit lan connection? Thanks for your input! And please feel free to share any advice or wisdom about using virtual machines for software development and the best ways to speed them up!

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• Bash script 'while read' loop causes 'broken pipe' error when run with GNU Parallel

  - by Joe White

  According to the GNU Parallel mailing list this is not a GNU Parallel-specific problem. They suggested that I post my problem here. The error I'm getting is a "broken pipe" error, but I feel I should first explain the context of my problem and what causes this error. It happens when trying to use any bash script containing a 'while read' loop in GNU Parallel. I have a basic bash script like this: #!/bin/bash # linkcheck.sh while read domain do host "$domain" done Assume that I want to pipe in a large list (250mb say). cat urllist | ./linkcheck.sh Running host command on 250mb worth of URLs is rather slow. To speed things up I want to break up the input into chunks before piping it and then run multiple jobs in parallel. GNU Parallel is capable of doing this. cat urllist | parallel --pipe -j0 parallel ./linkcheck.sh {} {} is substituted by the contents of urllist line-by-line. Assume that my systems default setup is capable of running 500ish jobs per instance of parallel. To get round this limitation we can parallelize Parallel itself: cat urllist | parallel -j10 --pipe parallel -j0 ./linkcheck.sh {} This will run 5000'ish jobs. It will also, sadly, cause the error "broken pipe" (bash FAQ). Yet the script starts to work if I remove the while read loop and take input directly from whatever is fed into {} e.g., #!/bin/bash # linkchecker.sh domain="$1" host "$1" Why will it not work with a while read loop? Is it safe to just turn off the SIGPIPE signal to stop the "broken pipe" message, or will that have side effects such as data corruption? Thanks for reading.

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• nginx inserting extra characters in Multi-status reply body

  - by user125011

  Here's the setup. I've got one server running apache/php hosting ownCloud. Among other things, I'm using to do CardDAV contact syncing. In order to make things work with my domain I have an nginx server running on the frontend as a reverse-proxy to the ownCloud server. My nginx config is as follows: server { listen 80; server_name cloud.mydomain.com; location / { proxy_set_header X-Forwarded-Host cloud.mydomain.com; proxy_set_header X-Forwarded-Proto http; proxy_set_header X-Forwarded-For $remote_addr; client_max_body_size 0; proxy_redirect off; proxy_pass http://server; } } The problem is that when my phone does a PROPFIND on the server, nginx adds extra characters to the content body that throw the phone off. Specifically, it prepends d611\r\n at the front of the body and appends 0\r\n\r\n to the end of the content. (I got this from wireshark.) It also re-chunks the result. How do I get nginx to send the original content as-is?

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