Search Results

Search found 19975 results on 799 pages for 'disk queue length'.

Page 620/799 | < Previous Page | 616 617 618 619 620 621 622 623 624 625 626 627  | Next Page >

• Block-level deduplicating filesystem

  - by James Haigh

  I'm looking for a deduplicating copy-on-write filesystem solution for general user data such as /home and backups of it. It should use online/inline/synchronous deduplication at the block-level using secure hashing (for negligible chance of collisions) such as SHA256 or TTH. Duplicate blocks need not even touch the disk. The idea is that I should be able to just copy /home/<user> to an external HDD with the same such filesystem to do a backup. Simple. No messing around with incremental backups where corruption to any of the snapshots will nearly always break all later snapshots, and no need to use a specific tool to delete or 'checkout' a snapshot. Everything should simply be done from the file browser without worry. Can you imagine how easy this would be? I'd never have to think twice about backing-up again! I don't mind a performance hit, reliability is the main concern. Although, with specific implementations of cp, mv and scp, and a file browser plugin, these operations would be very fast, especially when there is a lot of duplication as they would only need to transfer the absent blocks. Accidentally using conventional copy tools that do not integrate with the FS would merely take longer, waste some bandwidth when copying remotely and waste some CPU, as the duplicate data would be re-read, re-transferred and re-hashed (although nothing would be re-written), but would absolutely not corrupt anything. (Some filesharing software may also be able to benefit by integrating with the FS.) So what's the best way of doing this? I've looked at some options: lessfs - Looks unmaintained. Any good? [Opendedup/SDFS][3] - Java? Could I use this on Android?! What does [SDFS][4] stand for? [Btrfs][5] - Some patches floating around on mailing list archives, but no real support. [ZFS][6] - Hopefully they'll one day relicense under a true Free/Opensource GPL-compatible licence. Also, 2 years ago I had a go at an attempt in Python using Fuse at the file-level to be used over the top of a typical solid FS such as EXT4, but I found Fuse for Python underdocumented and didn't manage to implement all of the system calls. My first post here, so I can't post more than 2 links until I get over 10 rep: [3]: http://www.opendedup.org/ [4]: https://en.wikipedia.org/w/index.php?title=SDFS&action=edit&redlink=1 [5]: https://en.wikipedia.org/wiki/Btrfs#Features [6]: https://en.wikipedia.org/wiki/ZFS#Linux

  Read the article

• Getting a virus is *very* annoying

  - by bconlon

  I spent most of yesterday removing an annoying virus from my PC. I feel slightly foolish for getting one in the first place, but after so many years I guess I was always going to eventually succumb. I was also a little surprised at the failure of various tools at removing it. The virus would redirect the browser to websites including ‘licosearch’, ‘hugosearch’ and ‘facebook’, and the disk would be thrashing away infecting dlls in some way. I had the full up to date version of McAfee installed. This identified that there was an issue in some dlls on the system and was able to ‘fix’ them. But they kept getting re-infected. So I installed Microsoft Security Essentials and this too was able to identify and ‘fix’ the infected dlls. The system scans take forever and I really expected better results. I also tried Malwarebytes, Hitman Pro, AVG and Sophos to no avail. Eventually I thought I’d investigate myself. It turned out that on reboot, the virus would start 3 instances of Firefox.exe which I’m guessing would do bad things including infecting as many dlls on the system as possible. I removed Firefox and the virus cleverly then launched 3 instances of Chrome! So I uninstalled Chrome and yes, it then started to launch 3 instances of iexplore.exe. If I’m honest, by this stage I was just seeing if it would be able to use any of the browsers! As it was starting these on reboot, I looked in my User Startup folder and there was a <randomly named>.exe and several log files. I deleted these and rebooted. When I looked they had been recreated. So I then looked in the registry Run and RunOnce entries: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run. Sure enough there were entries to run a file in C:\Program Files\<random name folder>\<random name file>.exe. I deleted this and rebooted and it was fixed. I also looked in the event log and found a warning that Winlogon had failed to start the file C:\Program Files\<random name folder>\<random name file>.exe So I also checked HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon and this entry had also been changed. Finally I ran a full system scan to clean up any infected dlls. I hope it’s gone for good!  #

  Read the article

• Write and fprintf for file I/O

  - by Darryl Gove

  fprintf() does buffered I/O, where as write() does unbuffered I/O. So once the write() completes, the data is in the file, whereas, for fprintf() it may take a while for the file to get updated to reflect the output. This results in a significant performance difference - the write works at disk speed. The following is a program to test this: #include <fcntl.h #include <unistd.h #include <stdio.h #include <stdlib.h #include <errno.h #include <stdio.h #include <sys/time.h #include <sys/types.h #include <sys/stat.h static double s_time; void starttime() { s_time=1.0*gethrtime(); } void endtime(long its) { double e_time=1.0*gethrtime(); printf("Time per iteration %5.2f MB/s\n", (1.0*its)/(e_time-s_time*1.0)*1000); s_time=1.0*gethrtime(); } #define SIZE 10*1024*1024 void test_write() { starttime(); int file = open("./test.dat",O_WRONLY|O_CREAT,S_IWGRP|S_IWOTH|S_IWUSR); for (int i=0; i<SIZE; i++) { write(file,"a",1); } close(file); endtime(SIZE); } void test_fprintf() { starttime(); FILE* file = fopen("./test.dat","w"); for (int i=0; i<SIZE; i++) { fprintf(file,"a"); } fclose(file); endtime(SIZE); } void test_flush() { starttime(); FILE* file = fopen("./test.dat","w"); for (int i=0; i<SIZE; i++) { fprintf(file,"a"); fflush(file); } fclose(file); endtime(SIZE); } int main() { test_write(); test_fprintf(); test_flush(); } Compiling and running I get 0.2MB/s for write() and 6MB/s for fprintf(). A large difference. There's three tests in this example, the third test uses fprintf() and fflush(). This is equivalent to write() both in performance and in functionality. Which leads to the suggestion that fprintf() (and other buffering I/O functions) are the fastest way of writing to files, and that fflush() should be used to enforce synchronisation of the file contents.

  Read the article

• Is there a usage count for packages or programs?

  - by math

  Motivation: I want to remove applications I do not use to speed up my package processing tasks like dist upgrades, regular updates, but also for saving disk space and other reasons. I know this is a complex topic so first I will ask my question and second I will give some answers I already found out. Question: How do I find out which package I did not used at all? For example I always use the VLC so I could remove totem package. (Which I could have been used some day, yes.) Of course package dependencies could force me to have programs installed which I will never use. Notes: Find the packages which consume much space via synaptic: Select "Status" in lower left, select "Installed" in upper left, sort column on "size" in upper right. Then you can decide which big packages you really need. Use aptitude autoremove Use ubuntu-tweak's Janitor for removing old kernel packages, old configs, apt-cache entries, etc. Manually search for applications for a given task that you usually solve with your standard app. E.g. Movie player, Music player, Office program, Browser etc. (BTW: this is what I want to be helped with my question) When removing packages I always favour "apt-get purge" over "aptitude remove --purge" as aptitude often will also remove essential packages due to package dependencies. E.g. when removing "evolution" (as I use thunderbird) aptitude wants to remove also "ubuntu-desktop" and 756 other packages as well, while apt-get just removes evolution and its helping pacakges like evolution-common. Ubuntu lense gives me most recent used applications which are candidates for keeping :) Employ deborphan as I read in this related answer: How do I clean up my harddrive? I should certainly keep essential packages: Keep only essential packages This question is pretty much a duplicate of How to see what installed packages I have never used for cleaning purposes but covering only few aspects. However one answer suggests to use a program called unusedpkg but the link seems down. There is also a program called Kleen http://code.google.com/p/kleen/ but it won't compile in 11.10. However I hacked it to compile but the results are unusable, as for example the g++ package was marked as not used for 203, but actually I used it seconds ago for compiling Kleen itself ;) So don't use this tool. On http://wiki.debian.org/DebianPackageInformation I read the the package popularity-contest will produce log files with usage statistics. Unfortunately I didn't enabled the popularity contest so I can't find this log file.

  Read the article

• Update Errors in Xubuntu 12.10

  - by wil

  I updated by computer from 12.04 to 12.10 and after I finished updating when I turned on my computer I am unable to update my computer. I tried install a new copy of 13.04 but my cpu doesn't support pae. I have a IBM Thinkpad T42 with a 1.7 gigahertx Cpu. When updating through terminal This is the output. sudo apt-get upgrade: [sudo] password for wil: Reading package lists... Done Building dependency tree Reading state information... Done You might want to run 'apt-get -f install' to correct these. The following packages have unmet dependencies: linux-image-extra-3.5.0-34-generic : Depends: linux-image-3.5.0-34-generic but it is not installed linux-image-generic : Depends: linux-image-3.5.0-34-generic but it is not installed E: Unmet dependencies. Try using -f. sudo apt-get upgrade -f: Reading package lists... Done Building dependency tree Reading state information... Done Correcting dependencies... Done The following NEW packages will be installed: linux-image-3.5.0-34-generic 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. 3 not fully installed or removed. Need to get 0 B/11.8 MB of archives. After this operation, 25.9 MB of additional disk space will be used. Do you want to continue [Y/n]? y (Reading database ... 191530 files and directories currently installed.) Unpacking linux-image-3.5.0-34-generic (from .../linux-image-3.5.0-34-generic_3.5.0-34.55_i386.deb) ... This kernel does not support a non-PAE CPU. dpkg: error processing /var/cache/apt/archives/linux-image-3.5.0-34-generic_3.5.0-34.55_i386.deb (--unpack): subprocess new pre-installation script returned error exit status 1 No apport report written because MaxReports is reached already Examining /etc/kernel/postrm.d . run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.5.0-34-generic /boot/vmlinuz-3.5.0-34-generic run-parts: executing /etc/kernel/postrm.d/zz-update-grub 3.5.0-34-generic /boot/vmlinuz-3.5.0-34-generic Errors were encountered while processing: /var/cache/apt/archives/linux-image-3.5.0-34-generic_3.5.0-34.55_i386.deb E: Sub-process /usr/bin/dpkg returned an error code (1) wil@wil-ThinkPad-T42:~/Desktop$

  Read the article

• Identifying which pattern fits better.

  - by Daniel Grillo

  I'm developing a software to program a device. I have some commands like Reset, Read_Version, Read_memory, Write_memory, Erase_memory. Reset and Read_Version are fixed. They don't need parameters. Read_memory and Erase_memory need the same parameters that are Length and Address. Write_memory needs Lenght, Address and Data. For each command, I have the same steps in sequence, that are something like this sendCommand, waitForResponse, treatResponse. I'm having difficulty to identify which pattern should I use. Factory, Template Method, Strategy or other pattern. Edit I'll try to explain better taking in count the given comments and answers. I've already done this software and now I'm trying to refactoring it. I'm trying to use patterns, even if it is not necessary because I'm taking advantage of this little software to learn about some patterns. Despite I think that one (or more) pattern fits here and it could improve my code. When I want to read version of the software of my device, I don't have to assembly the command with parameters. It is fixed. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. To read a portion of the memory (maximum of 256 bytes), I have to assembly the command using the parameters Len and Address. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. To write a portion in the memory (maximum of 256 bytes), I have to assembly the command using the parameters Len, Address and Data. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. I think that I could use Template Method because I have almost the same algorithm for all. But the problem is some commands are fixes, others have 2 or 3 parameters. I think that parameters should be passed on the constructor of the class. But each class will have a constructor overriding the abstract class constructor. Is this a problem for the template method? Should I use other pattern?

  Read the article

• why are my players drawn top the side of my viewport

  - by Jetbuster

  Following this admittedly brilliant and clean 2d camera class I have a camera on each player, and it works for multiplayer and i've divided the screen into two sections for split screen by giving each camera a viewport. However in the game it looks like this I'm not sure if thats their position relative to the screen or what The relevant gameScreen code, the makePlayers is setup so it could theoretically work for up to 4 players private void makePlayers() { int rowCount = 1; if (NumberOfPlayers > 2) rowCount = 2; players = new Player[NumberOfPlayers]; for (int i = 0; i < players.Length; i++) { int xSize = GameRef.Window.ClientBounds.Width / 2; int ySize = GameRef.Window.ClientBounds.Height / rowCount; int col = i % rowCount; int row = i / rowCount; int xPoint = 0 + xSize * row; int yPoint = 0 + ySize * col; Viewport viewport = new Viewport(xPoint, yPoint, xSize, ySize); Vector2 playerPosition = new Vector2(viewport.TitleSafeArea.X + viewport.TitleSafeArea.Width / 2, viewport.TitleSafeArea.Y + viewport.TitleSafeArea.Height / 2); players[i] = new Player(playerPosition, playerSprites[i], GameRef, viewport); } //players[1].Keyboard = true; } public override void Draw(GameTime gameTime) { base.Draw(gameTime); foreach (Player player in players) { GraphicsDevice.Viewport = player.PlayerCamera.ViewPort; GameRef.spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, SamplerState.PointClamp, null, null, null, player.PlayerCamera.Transform); map.Draw(GameRef.spriteBatch); // Draw the Player player.Draw(GameRef.spriteBatch); // Draw UI screen elements GraphicsDevice.Viewport = Viewport; ControlManager.Draw(GameRef.spriteBatch); GameRef.spriteBatch.End(); } } the player's initialize and draw methods are like so internal void Initialize() { this.score = 0; this.angle = (float)(Math.PI * 0 / 180);//Start sprite at it's default rotation int width = utils.scaleInt(picture.Width, imageScale); int height = utils.scaleInt(picture.Height, imageScale); this.hitBox = new HitBox(new Vector2(centerPos.X - width / 2, centerPos.Y - height / 2), width, height, Color.Black, game.Window.ClientBounds); playerCamera.Initialize(); } #region Methods public void Draw(SpriteBatch spriteBatch) { //Console.WriteLine("Hitbox: X({0}),Y({1})", hitBox.Points[0].X, hitBox.Points[0].Y); //Console.WriteLine("Image: X({0}),Y({1})", centerPos.X, centerPos.Y); Vector2 orgin = new Vector2(picture.Width / 2, picture.Height / 2); hitBox.Draw(spriteBatch); utils.DrawCrosshair(spriteBatch, Position, game.Window.ClientBounds, Color.Red); spriteBatch.Draw(picture, Position, null, Color.White, angle, orgin, imageScale, SpriteEffects.None, 0.1f); } as I said I think I'm gonna need to do something with the render position but I'm to entirely sure what or how it would be elegant to say the least

  Read the article

• Implementing a Custom Coherence PartitionAssignmentStrategy

  - by jpurdy

  A recent A-Team engagement required the development of a custom PartitionAssignmentStrategy (PAS). By way of background, a PAS is an implementation of a Java interface that controls how a Coherence partitioned cache service assigns partitions (primary and backup copies) across the available set of storage-enabled members. While seemingly straightforward, this is actually a very difficult problem to solve. Traditionally, Coherence used a distributed algorithm spread across the cache servers (and as of Coherence 3.7, this is still the default implementation). With the introduction of the PAS interface, the model of operation was changed so that the logic would run solely in the cache service senior member. Obviously, this makes the development of a custom PAS vastly less complex, and in practice does not introduce a significant single point of failure/bottleneck. Note that Coherence ships with a default PAS implementation but it is not used by default. Further, custom PAS implementations are uncommon (this engagement was the first custom implementation that we know of). The particular implementation mentioned above also faced challenges related to managing multiple backup copies but that won't be discussed here. There were a few challenges that arose during design and implementation: Naive algorithms had an unreasonable upper bound of computational cost. There was significant complexity associated with configurations where the member count varied significantly between physical machines. Most of the complexity of a PAS is related to rebalancing, not initial assignment (which is usually fairly simple). A custom PAS may need to solve several problems simultaneously, such as: Ensuring that each member has a similar number of primary and backup partitions (e.g. each member has the same number of primary and backup partitions) Ensuring that each member carries similar responsibility (e.g. the most heavily loaded member has no more than one partition more than the least loaded). Ensuring that each partition is on the same member as a corresponding local resource (e.g. for applications that use partitioning across message queues, to ensure that each partition is collocated with its corresponding message queue). Ensuring that a given member holds no more than a given number of partitions (e.g. no member has more than 10 partitions) Ensuring that backups are placed far enough away from the primaries (e.g. on a different physical machine or a different blade enclosure) Achieving the above goals while ensuring that partition movement is minimized. These objectives can be even more complicated when the topology of the cluster is irregular. For example, if multiple cluster members may exist on each physical machine, then clearly the possibility exists that at certain points (e.g. following a member failure), the number of members on each machine may vary, in certain cases significantly so. Consider the case where there are three physical machines, with 3, 3 and 9 members each (respectively). This introduces complexity since the backups for the 9 members on the the largest machine must be spread across the other 6 members (to ensure placement on different physical machines), preventing an even distribution. For any given problem like this, there are usually reasonable compromises available, but the key point is that objectives may conflict under extreme (but not at all unlikely) circumstances. The most obvious general purpose partition assignment algorithm (possibly the only general purpose one) is to define a scoring function for a given mapping of partitions to members, and then apply that function to each possible permutation, selecting the most optimal permutation. This would result in N! (factorial) evaluations of the scoring function. This is clearly impractical for all but the smallest values of N (e.g. a partition count in the single digits). It's difficult to prove that more efficient general purpose algorithms don't exist, but the key take away from this is that algorithms will tend to either have exorbitant worst case performance or may fail to find optimal solutions (or both) -- it is very important to be able to show that worst case performance is acceptable. This quickly leads to the conclusion that the problem must be further constrained, perhaps by limiting functionality or by using domain-specific optimizations. Unfortunately, it can be very difficult to design these more focused algorithms. In the specific case mentioned, we constrained the solution space to very small clusters (in terms of machine count) with small partition counts and supported exactly two backup copies, and accepted the fact that partition movement could potentially be significant (preferring to solve that issue through brute force). We then used the out-of-the-box PAS implementation as a fallback, delegating to it for configurations that were not supported by our algorithm. Our experience was that the PAS interface is quite usable, but there are intrinsic challenges to designing PAS implementations that should be very carefully evaluated before committing to that approach.

  Read the article

• No More NCrunch For Me

  - by Steve Wilkes

  When I opened up Visual Studio this morning, I was greeted with this little popup: NCrunch is a Visual Studio add-in which runs your tests while you work so you know if and when you've broken anything, as well as providing coverage indicators in the IDE and coverage metrics on demand. It recently went commercial (which I thought was fair enough), and time is running out for the free version I've been using for the last couple of months. From my experiences using NCrunch I'm going to let it expire, and go about my business without it. Here's why. Before I start, let me say that I think NCrunch is a good product, which is to say it's had a positive impact on my programming. I've used it to help test-drive a library I'm making right from the start of the project, and especially at the beginning it was very useful to have it run all my tests whenever I made a change. The first problem is that while that was cool to start with, it’s recently become a bit of a chore. Problems Running Tests NCrunch has two 'engine modes' in which it can run tests for you - it can run all your tests when you make a change, or it can figure out which tests were impacted and only run those. Unfortunately, it became clear pretty early on that that second option (which is marked as 'experimental') wasn't really working for me, so I had to have it run everything. With a smallish number of tests and while I was adding new features that was great, but I've now got 445 tests (still not exactly loads) and am more in a 'clean and tidy' mode where I know that a change I'm making will probably only affect a particular subset of the tests. With that in mind it's a bit of a drag sitting there after I make a change and having to wait for NCrunch to run everything. I could disable it and manually run the tests I know are impacted, but then what's the point of having NCrunch? If the 'impacted only' engine mode worked well this problem would go away, but that's not what I found. Secondly, what's wrong with this picture? I've got 445 tests, and NCrunch has queued 455 tests to run. So it's queued duplicate tests - in this quickly-screenshotted case 10, but I've seen the total queue get up over 600. If I'm already itchy waiting for it to run all my tests against a change I know only affects a few, I'm even itchier waiting for it to run a lot of them twice. Problems With Code Coverage NCrunch marks each line of code with a dot to say if it's covered by tests - a black dot says the line isn't covered, a red dot says it's covered but at least one of the covering tests is failing, and a green dot means all the covering tests pass. It also calculates coverage statistics for you. Unfortunately, there's a couple of flaws in the coverage. Firstly, it doesn't support ExcludeFromCodeCoverage attributes. This feature has been requested and I expect will be included in a later release, but right now it doesn't. So this: ...is counted as a non-covered line, and drags your coverage statistics down. Hmph. As well as that, coverage of certain types of code is missed. This: ...is definitely covered. I am 100% absolutely certain it is, by several tests. NCrunch doesn't pick it up, down go my coverage statistics. I've had NCrunch find genuinely uncovered code which I've been able to remove, and that's great, but what's the coverage percentage on this project? Umm... I don't know. Conclusion None of these are major, tool-crippling problems, and I expect NCrunch to get much better in future releases. The current version has some great features, like this: ...that's a line of code with a failing test covering it, and NCrunch can run that failing test and take me to that line exquisitely easily. That's awesome! I'd happily pay for a tool that can do that. But here's the thing: NCrunch (currently) costs $159 (about £100) for a personal licence and $289 (about £180) for a commercial one. I'm not sure which one I'd need as my project is a personal one which I'm intending to open-source, but I'm a professional, self-employed developer, but in any case - that seems like a lot of money for an imperfect tool. If it did everything it's advertised to do more or less perfectly I'd consider it, but it doesn't. So no more NCrunch for me.

  Read the article

• Exalytics OBI11g Partner Training 3-day hands-on Workshops

  - by Mike.Hallett(at)Oracle-BI&EPM

  These FREE to OPN Partners hands-on workshops highlight both the hardware and software components that are engineered to work together to deliver Oracle Exalytics - an optimized version of the industry-leading Oracle TimesTen In-Memory Database with analytic extensions, a highly scalable Oracle server designed specifically for in-memory business intelligence, and Oracle's proven Business Intelligence Foundation (OBI 11g v 11.1.1.6 and Essbase) with enhanced visualization capabilities and performance optimizations. Priority will be given to Partner individuals who have passed or scheduled to take the Oracle Business Intelligence Foundation Suite 11g Essentials (1Z1-591) exam, and to Partners who have purchased an Exalytics for their own data centres to demonstrate it to their clients. Topics covered will include: Exalytics Architectural Overview Upgrade and Lifecycle Management Times Ten for Exalytics Summary Advisor Utility Essbase and EPM System on Exalytics Dashboard and Analysis Interactions OBIEE 11.1.1.6 Features and Advanced Topics After taking this course, you will be well prepared to architect, build, demo, and implement an end-to-end Exalytics solution.You will also be able to extend your current analytical and enterprise performance management application implementations with numerous Oracle technologies specifically enhanced to take advantage of the compute capacity and in-memory capabilities of Oracle Exalytics. Prerequisites Experience and understanding of OBIEE 11g is required ·       Previous attendance of Oracle Business Intelligence Foundation Suite Workshop or BIEE 11g Introduction Workshop is highly recommended, and priority will be given to Partner individuals who have passed or scheduled to take the Oracle Business Intelligence Foundation Suite 11g Essentials (1Z1-591) exam. Good understanding of data warehousing and data modelling for reporting and analysis purpose.  Strong experience with database technologies preferred Attendee to provide their own laptops which must meet the following minimum hardware/software requirements: Hardware Minimum 8GB RAM 60 GB free disk space (includes staging) USB 2.0 port (at least one available) It is strongly recommended that you bring a mouse. You will be working in a development environment and using the mouse heavily. Software One of the following operating systems: 64-bit Windows host/laptop OS 64-bit host/laptop OS with a Windows VM (XP, Server, or Win 7, BIC2g, etc.) Internet Explorer 7.x/8.x or Firefox 3.5.x WINRAR or 7ziputility to unzip workshop files: Download-able from http://www.win-rar.com/download.html Download-able from http://www.7zip.com/ Oracle VirtualBox 4.0.2 or higher Downloadable from http://www.virtualbox.org/wiki/Downloads CPU virtualization mode needs to be enabled. We will provide guidance on the day of the workshop.  Attendees will be given a VirtualBox image containing a pre-installed Oracle Exalytics environment. Register Here for 3-day Workshops: 11-Dec-12 Birmingham UK 29-Jan-13 Utrecht NL 12-Feb-13 Frankfurt Germany 12-Mar-13 Moscow Russia

  Read the article

• Concurrency Utilities for Java EE Early Draft (JSR 236)

  - by arungupta

  Concurrency Utilities for Java EE is being worked as JSR 236 and has released an Early Draft. It provides concurrency capabilities to Java EE application components without compromising container integrity. Simple (common) and advanced concurrency patterns are easily supported without sacrificing usability. Using Java SE concurrency utilities such as java.util.concurrent API, java.lang.Thread and java.util.Timer in a Java EE application component such as EJB or Servlet are problematic since the container and server have no knowledge of these resources. JSR 236 enables concurrency largely by extending the Concurrency Utilities API developed under JSR-166. This also allows a consistency between Java SE and Java EE concurrency programming model. There are four main programming interfaces available: ManagedExecutorService ManagedScheduledExecutorService ContextService ManagedThreadFactory ManagedExecutorService is a managed version of java.util.concurrent.ExecutorService. The implementations of this interface are provided by the container and accessible using JNDI reference: <resource-env-ref>  <resource-env-ref-name>    concurrent/BatchExecutor  </resource-env-ref-name>  <resource-env-ref-type>    javax.enterprise.concurrent.ManagedExecutorService  </resource-env-ref-type><resource-env-ref> and available as: @Resource(name="concurrent/BatchExecutor")ManagedExecutorService executor; Its recommended to bind the JNDI references in the java:comp/env/concurrent subcontext. The asynchronous tasks that need to be executed need to implement java.lang.Runnable or java.util.concurrent.Callable interface as: public class MyTask implements Runnable { public void run() { // business logic goes here }} OR public class MyTask2 implements Callable<Date> {  public Date call() { // business logic goes here   }} The task is then submitted to the executor using one of the submit method that return a Future instance. The Future represents the result of the task and can also be used to check if the task is complete or wait for its completion. Future<String> future = executor.submit(new MyTask(), String.class);. . .String result = future.get(); Another example to submit tasks is: class MyTask implements Callback<Long> { . . . }class MyTask2 implements Callback<Date> { . . . }ArrayList<Callable> tasks = new ArrayList<();tasks.add(new MyTask());tasks.add(new MyTask2());List<Future<Object>> result = executor.invokeAll(tasks); The ManagedExecutorService may be configured for different properties such as: Hung Task Threshold: Time in milliseconds that a task can execute before it is considered hung Pool Info Core Size: Number of threads to keep alive Maximum Size: Maximum number of threads allowed in the pool Keep Alive: Time to allow threads to remain idle when # of threads > Core Size Work Queue Capacity: # of tasks that can be stored in inbound buffer Thread Use: Application intend to run short vs long-running tasks, accordingly pooled or daemon threads are picked ManagedScheduledExecutorService adds delay and periodic task running capabilities to ManagedExecutorService. The implementations of this interface are provided by the container and accessible using JNDI reference: <resource-env-ref>  <resource-env-ref-name>    concurrent/BatchExecutor  </resource-env-ref-name>  <resource-env-ref-type>    javax.enterprise.concurrent.ManagedExecutorService  </resource-env-ref-type><resource-env-ref> and available as: @Resource(name="concurrent/timedExecutor")ManagedExecutorService executor; And then the tasks are submitted using submit, invokeXXX or scheduleXXX methods. ScheduledFuture<?> future = executor.schedule(new MyTask(), 5, TimeUnit.SECONDS); This will create and execute a one-shot action that becomes enabled after 5 seconds of delay. More control is possible using one of the newly added methods: MyTaskListener implements ManagedTaskListener {  public void taskStarting(...) { . . . }  public void taskSubmitted(...) { . . . }  public void taskDone(...) { . . . }  public void taskAborted(...) { . . . } }ScheduledFuture<?> future = executor.schedule(new MyTask(), 5, TimeUnit.SECONDS, new MyTaskListener()); Here, ManagedTaskListener is used to monitor the state of a task's future. ManagedThreadFactory provides a method for creating threads for execution in a managed environment. A simple usage is: @Resource(name="concurrent/myThreadFactory")ManagedThreadFactory factory;. . .Thread thread = factory.newThread(new Runnable() { . . . }); concurrent/myThreadFactory is a JNDI resource. There is lot of interesting content in the Early Draft, download it, and read yourself. The implementation will be made available soon and also be integrated in GlassFish 4 as well. Some references for further exploring ... Javadoc Early Draft Specification concurrency-ee-spec.java.net [email protected]

  Read the article

• Draw images with warped triangles on a web server [migrated]

  - by epologee

  The scenario The Flash front end of my current project produces images that a web server needs to combine into a video. Both frame-rate and frame-resolution are sizeable enough that sending an image sequence to the back end is not feasible (in both time and client bandwidth). Instead, we're trying to recreate the image drawing on the back end as well. Correct and slow, or incorrect and fast The problem is that this involves quite a bit of drawing textured triangles, and two solutions we found in Python (here and there) are so inefficient, that the drawing takes about 60 seconds per frame, resulting in a whopping 7,5 hours of processing time for a 30 second clip. Unacceptable. When using a PHP-module to send commands to ImageMagick for image manipulation, the whole process is super fast (tenths of a second per frame), but ImageMagick seems to be unable to draw triangles the way we do it in the front end, so the final results do not match. Unacceptable. What I'm asking here, is if there's someone who would know a way to solve this issue, by any means necessary that would run on a web server. Warping an image Let me explain the process of the front end: Perform a Delaunay calculation on points in an image to get an evenly distributed mesh of triangles. Offset the points/vertices in the mesh, distorting or warping the image. Draw the warped triangles on a new bitmap. We can send the results (coordinates) of steps 1 and 2 to the back end, to then draw the warped triangles and save it to an image on disk (or append as a frame to the video). But that last step is what I need help with. The Question Is there an alternative to ImageMagick that can draw triangles in a bitmap? Is there some other library, like a C library, that would allow us to do this? Or could we achieve this effect more easily by switching back end technologies, like Ruby? (.Net and Java are, unfortunately, not really options right now) Many thanks. EP. P.S. I'd appreciate re-tagging efforts, I don't quite know what labels to put on this question. Thanks!

  Read the article

• 3D collision physics. Response when hitting wall, floor or roof

  - by GlamCasvaluir

  I am having problem with the most basic physic response when the player collide with static wall, floor or roof. I have a simple 3D maze, true means solid while false means air: bool bMap[100][100][100]; The player is a sphere. I have keys for moving x++, x--, y++, y-- and diagonal at speed 0.1f (0.1 * ftime). The player can also jump. And there is gravity pulling the player down. Relative movement is saved in: relx, rely and relz. One solid cube on the map is exactly 1.0f width, height and depth. The problem I have is to adjust the player position when colliding with solids, I don't want it to bounce or anything like that, just stop. But if moving diagonal left/up and hitting solid up, the player should continue moving left, sliding along the wall. Before moving the player I save the old player position: oxpos = xpos; oypos = ypos; ozpos = zpos; vec3 direction; direction = vec3(relx, rely, relz); xpos += direction.x*ftime; ypos += direction.y*ftime; zpos += direction.z*ftime; gx = floor(xpos+0.25); gy = floor(ypos+0.25); gz = floor(zpos+0.25); if (bMap[gx][gy][gz] == true) { vec3 normal = vec3(0.0, 0.0, 1.0); // <- Problem. vec3 invNormal = vec3(-normal.x, -normal.y, -normal.z) * length(direction * normal); vec3 wallDir = direction - invNormal; xpos = oxpos + wallDir.x; ypos = oypos + wallDir.y; zpos = ozpos + wallDir.z; } The problem with my version is that I do not know how to chose the correct normal for the cube side. I only have the bool array to look at, nothing else. One theory I have is to use old values of gx, gy and gz, but I do not know have to use them to calculate the correct cube side normal.

  Read the article

• Designing Snake AI

  - by Ronald

  I'm new to this gamedev stackechange but have used the math and cs sites before. So, I'm in a competition to create AI for a snake that will compete with 3 other snakes in 5 minute rounds where the rules are much like the traditional Nokia snake game except that there are 4 snakes, the board is 50x50 and there are a number of small obstacles on the field. Like the Nokia game, your snake grows when you get to the fruit and if you crash into yourself, another snake or the wall you die. The game runs with a 50ms delay between moves and the server sends the new game state every 50ms which the code must analyze and what not and output the next move. The winner is the snake who had the longest length at any point in the game. Tie breakers are decided by kills. So far what I have done is implemented an A* graph search from each snake to determine if my snake is the closest to the apple and if it is, it goes for the apple. Otherwise, I made a neat little algorithm to determine the emptiest area of the board, which my snake goes for, to anticipate the next apple. Other than this I have some small survivability checks to ensure my snake isn't walking into a trap that it can't get out and if it does get stuck, I have something to give it a better chance of getting out. ... Anyway, I've tested my snake on a test server and it does quite well. Generally, my strategy of only going for the apple when its a sure thing and finding space when its not makes it grow faster than any other snakes (some snakes do a similar thing but often just go to the middle or a corner) sometimes it wins these trial games but is more often than not beaten by the same snake who seems to have the edge on survivability(my snake grows quicker but then dies somehow and this other snake just plods slowly along and wins on consistency. So I was wondering about any ideas anyone has to try and improve my snake. Or maybe ideas at a new approach to take. My functions and classes are good so changes that might seem drastic shouldn't be too bad. I encourage all ideas. Any thoughts ??

  Read the article

• Best way to determine surface normal for a group of pixels?

  - by Paul Renton

  One of my current endeavors is creating a 2D destructible terrain engine for iOS Cocos2D (See https://github.com/crebstar/PWNDestructibleTerrain ). It is in an infant stages no doubt, but I have made significant progress since starting a couple weeks ago. However, I have run into a bit of a performance road block with calculating surface normals. Note: For my destructible terrain engine, an alpha of 0 is considered to not be solid ground. The method posted below works just great given small rectangles, such as n < 30. Anything above 30 causes a dip in the frame rate. If you approach 100x100 then you might as well read a book while the sprite attempts to traverse the terrain. At the moment this is the best I can come up with for altering the angle on a sprite as it roams across terrain (to get the angle for a sprite's orientation just take dot product of 100 * normal * (1,0) vector). -(CGPoint)getAverageSurfaceNormalAt:(CGPoint)pt withRect:(CGRect)area { float avgX = 0; float avgY = 0; ccColor4B color = ccc4(0, 0, 0, 0); CGPoint normal; float len; for (int w = area.size.width; w >= -area.size.width; w--) { for (int h = area.size.height; h >= -area.size.height; h--) { CGPoint pixPt = ccp(w + pt.x, h + pt.y); if ([self pixelAt:pixPt colorCache:&color]) { if (color.a != 0) { avgX -= w; avgY -= h; } // end inner if } // end outer if } // end inner for } // end outer for len = sqrtf(avgX * avgX + avgY * avgY); if (len == 0) { normal = ccp(avgX, avgY); } else { normal = ccp(avgX/len, avgY/len); } // end if return normal; } // end get My problem is I have sprites that require larger rectangles in order for their movement to look realistic. I considered doing a cache of all surface normals, but this lead to issues of knowing when to recalculate the surface normals and these calculations also being quite expensive (also how large should the blocks be?). Another smaller issue is I don't know how to properly treat the case when length is = 0. So I am stuck... Any advice from the community would be greatly appreciated! Is my method the best possible one? Or should I rethink the algorithm? I am new to game development and always looking to learn new tips and tricks.

  Read the article

• Why is everything crashing?

  - by Kopkins

  I've been using Ubuntu for a while now and I love it, I wouldn't think of using another OS unless I can't fix this issue. The install I'm on is only around a month and a half old. I'm running 12.04 64bit on a 8,1 MBP. Up until around 2 weeks ago everything was running smoothly. Around then applications started crashing and weird things started happening. At first I thought it was just certain applications. The first thing to start giving me trouble was compiz. Occasionally compiz will stop decorating windows and lost many other functionalities. running compiz --replace fixes this, but I don't feel like doing it usually once a day. The other thing with this is that after running compiz --replace, my conky window gets lost somewhere and so I run killall conky && conky -c .conkyrc. But this isn't with just a couple applications, it seems like it is proliferating through my system. Last week fontforge started crashing while doing whatever task. So I ended up unable to finish what I was working on to completeness. Didn't find a fix. Today rhythmbox started crashing. Whenever I try to play anything, Rhythmbox becomes unresponsive and needs to be forced to close. When I try to do certain things with the disk utility, it crashes. I get the Ubuntu has experienced an internal error message much more often than I would like. Frequently applications stop appearing in the launcher. Wine almost never does anymore. After not being active for a little while, thunderbird can only fetch my mail after restarting wireless, sudo rmmod b43 && sudo modprobe b43 Occasionally some of my startup apps don't start. What is my best option here? Could they be bugs? I don't want to submit a ton of vague bug reports. Reinstall? switch OS? Thank you to anyone who responds. Kopkins

  Read the article

• How are OpenGL ES 1 framebuffers and textures sized?

  - by jens

  I am trying to draw to a texture using a framebuffer using OpenGL ES 1.1 on Android, Java. Afterwords I want to overlay this texture full-screen over my game. In theory, this works like a charm, but somehow the coordinates are off. For testing I drew something at (0,0) with width and height 200, and it partly is off-screen. This is how I create the framebuffer: fb = new int[1]; depthRb = new int[1]; renderTex = new int[1]; gl11ep.glGenFramebuffersOES(1, fb, 0); gl11ep.glGenRenderbuffersOES(1, depthRb, 0); // the depth buffer gl.glGenTextures(1, renderTex, 0);// generate texture gl.glBindTexture(GL10.GL_TEXTURE_2D, renderTex[0]); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_REPEAT); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_REPEAT); texBuffer = ByteBuffer.allocateDirect(buf.length*4).order(ByteOrder.nativeOrder()).asIntBuffer(); gl.glTexImage2D(GL10.GL_TEXTURE_2D, 0, GL10.GL_LUMINANCE, texW, texH, 0, GL10.GL_LUMINANCE, GL10.GL_UNSIGNED_BYTE, texBuffer); gl11ep.glBindRenderbufferOES(GL11ExtensionPack.GL_RENDERBUFFER_OES, depthRb[0]); gl11ep.glRenderbufferStorageOES(GL11ExtensionPack.GL_RENDERBUFFER_OES, GL11ExtensionPack.GL_DEPTH_COMPONENT16, texW, texH); Before I draw, I do this: gl11ep.glBindFramebufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, fb[0]); gl.glClearColor(0f, 0f, 0f, 0f); // specify texture as color attachment gl11ep.glFramebufferTexture2DOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, GL11ExtensionPack.GL_COLOR_ATTACHMENT0_OES, GL10.GL_TEXTURE_2D, renderTex[0], 0); // attach render buffer as depth buffer gl11ep.glFramebufferRenderbufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, GL11ExtensionPack.GL_DEPTH_ATTACHMENT_OES, GL11ExtensionPack.GL_RENDERBUFFER_OES, depthRb[0]); I set texW = 1024 and texH = 512. When rendering this texture fullscreen, with a lightmask (size 200x200) placed at (0, 0) and (texW/2, texH/2). You can see that it seems like the coordinate system doesnt start at (0,0) as that light overlaps the screen and the images are not drawn as squares (my lightcone-texture is a circle, not an ellipse). So, how is the coordinate system of this offscreen-drawn texture defined? Thanks

  Read the article

• OAuth with RestSharp in Windows Phone

  - by midoBB

  Nearly every major API provider uses OAuth for the user authentication and while it is easy to understand the concept, using it in a Windows Phone app isn’t pretty straightforward. So for this quick tutorial we will be using RestSharp for WP7 and the API from getglue.com (an entertainment site) to authorize the user. So the first step is to get the OAuth request token and then we redirect our browserControl to the authorization URL private void StartLogin() {   var client = new RestClient("https://api.getglue.com/"); client.Authenticator = OAuth1Authenticator.ForRequestToken("ConsumerKey", "ConsumerSecret"); var request = new RestRequest("oauth/request_token"); client.ExecuteAsync(request, response => { _oAuthToken = GetQueryParameter(response.Content, "oauth_token"); _oAuthTokenSecret = GetQueryParameter(response.Content, "oauth_token_secret"); string authorizeUrl = "http://getglue.com/oauth/authorize" + "?oauth_token=" + _oAuthToken + "&style=mobile"; Dispatcher.BeginInvoke(() => { browserControl.Navigate(new Uri(authorizeUrl)); }); }); } private static string GetQueryParameter(string input, string parameterName) { foreach (string item in input.Split('&')) { var parts = item.Split('='); if (parts[0] == parameterName) { return parts[1]; } } return String.Empty; } Then we listen to the browser’s Navigating Event private void Navigating(Microsoft.Phone.Controls.NavigatingEventArgs e) { if (e.Uri.AbsoluteUri.Contains("oauth_callback")) { var arguments = e.Uri.AbsoluteUri.Split('?'); if (arguments.Length < 1) return; GetAccessToken(arguments[1]); } } private void GetAccessToken(string uri) { var requestToken = GetQueryParameter(uri, "oauth_token"); var client = new RestClient("https://api.getglue.com/"); client.Authenticator = OAuth1Authenticator.ForAccessToken(ConsumerKey, ConsumerSecret, _oAuthToken, _oAuthTokenSecret); var request = new RestRequest("oauth/access_token"); client.ExecuteAsync(request, response => { AccessToken = GetQueryParameter(response.Content, "oauth_token"); AccessTokenSecret = GetQueryParameter(response.Content, "oauth_token_secret"); UserId = GetQueryParameter(response.Content, "glue_userId"); }); } Now to test it we can access the user’s friends list var client = new RestClient("http://api.getglue.com/v2"); client.Authenticator = OAuth1Authenticator.ForProtectedResource(ConsumerKey, ConsumerSecret, GAccessToken, AccessTokenSecret); var request = new RestRequest("/user/friends"); request.AddParameter("userId", UserId,ParameterType.GetOrPost); // request.AddParameter("category", "all",ParameterType.GetOrPost); client.ExecuteAsync(request, response => { TreatFreindsList(); }); And that’s it now we can access all OAuth methods using RestSharp.

  Read the article

• How do you turn on the customizable gnome-panel features (like gnome-applets) in Precise?

  - by chriv

  I resurrected a broken laptop today. I took out the HDD, put it in a USB 3.0 enclosure, and created a VM that would use it. It was running lucid. I took a screenshot of the desktop before I started "do-release-upgrade", because from experience, I will never have my GUI back the way I want it again. I know how to install gnome-panel to get back the "Gnome Classic" session option. I know how to put my minimize, maximize, and close buttons back in the upper-right hand corner of windows (where they belong). I know how to use gdm instead of lightdm. Unity gets worse in every version (and the other desktop OS is going to be even worse with Metro). Here's what I don't know (in order of importance): 1. How do you make the panels in gnome (gnome-panel, to be precise) customizable again (like they were in older versions of Ubuntu)? 2. How do you install applets in the panels now (right-click is now ignored)? 3. How can you customize all of the window elements (like you could in older versions of Ubuntu)? I can't remember much about maverick, natty, or oneiric (except their names), so I don't know exactly when I lost these capabilities. Edit: (no screenshot), my StackExchange reputation (on other StackExchange sites) doesn't carry over to this site, so I can't post the screenshot. Take a look at the panels in the screen hot. They are nice, compact, and VERY functional (disk mounter applet, frequently used shortcuts, workspaces, show desktop, kill window, and trash icons, etc.) Notice how small the fonts (and how little real estate they waste). You can't notice the compact title bars, fonts, and window icons in this screen shot (since I redacted the rest of the desktop), but it's the same story there. Please help. I don't want to learn another distro, but Ubuntu gets less customizable with every "upgrade." Screenshot (not an inline image, since I don't have the reputation yet)... i.stack.imgur.com/puoUT.png

  Read the article

• Weird Ubuntu Desktop Boot Partition On External Hard Drive

  - by Magnitus

  I have a Thinkpad with Windows 7. Last time I installed an Ubuntu/Windows dual boot, Windows was never same after and regularly got corrupted so this time, I installed Ubuntu on a separate external hard drive. I took a 500 GB external hard drive and used Windows to shrink the partition on it to 400 GB, freeing 100 GB to install Ubuntu. Then I modified the booting priority of my computer to boot from the external hard drive if present. Then, I installed Ubuntu desktop on the external hard drive using a DVD, picked the most simplistic partitioning scheme I could get away with (didn't go auto as it didn't include the external hard drive as a choice) and voilà. Fast forward some time and I'm trying to refresh my understanding of Linux partitions to install a bunch of servers, so I'm looking at the current partitioning scheme on my external hard drive and find the boot partition puzzling... sda is my integrated hard drive with Windows 7. sdb is my Ubuntu desktop external hard drive. Running parted on sdb, I get this: (parted) print Model: WD My Passport 0740 (scsi) Disk /dev/sdb: 500GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 1049kB 393GB 393GB primary ntfs boot 2 393GB 500GB 107GB extended 5 393GB 425GB 32.8GB logical linux-swap(v1) 6 425GB 500GB 74.6GB logical ext4 At this point, I'm wondering why the ntfs partition is flagged as "boot" and not my ext4 partition which is the partition that contains / (and by extension, /boot since it's not on its own separate partition). Looking at mtab only confirms what I already know: eric@eric-ThinkPad-W530:~$ sudo cat /etc/mtab /dev/sdb6 / ext4 rw,errors=remount-ro 0 0 proc /proc proc rw,noexec,nosuid,nodev 0 0 sysfs /sys sysfs rw,noexec,nosuid,nodev 0 0 none /sys/fs/cgroup tmpfs rw 0 0 none /sys/fs/fuse/connections fusectl rw 0 0 none /sys/kernel/debug debugfs rw 0 0 none /sys/kernel/security securityfs rw 0 0 udev /dev devtmpfs rw,mode=0755 0 0 devpts /dev/pts devpts rw,noexec,nosuid,gid=5,mode=0620 0 0 tmpfs /run tmpfs rw,noexec,nosuid,size=10%,mode=0755 0 0 none /run/lock tmpfs rw,noexec,nosuid,nodev,size=5242880 0 0 none /run/shm tmpfs rw,nosuid,nodev 0 0 none /run/user tmpfs rw,noexec,nosuid,nodev,size=104857600,mode=0755 0 0 none /sys/fs/pstore pstore rw 0 0 systemd /sys/fs/cgroup/systemd cgroup rw,noexec,nosuid,nodev,none,name=systemd 0 0 gvfsd-fuse /run/user/1000/gvfs fuse.gvfsd-fuse rw,nosuid,nodev,user=eric 0 0 /dev/sdb1 /media/eric/My\040Passport fuseblk rw,nosuid,nodev,allow_other,default_permissions,blksize=4096 0 0 My lack of understanding concerning this is not vital to anything (this is only my development desktop partition), but somehow annoys me. Any insight that could shed some light on this would be welcome.

  Read the article

• 2D collision resolving

  - by Philippe Paré

  I've just worked out an AABB collision algorithm for my 2D game and I was very satisfied until I found out it only works properly with movements of 1 in X and 1 in Y... here it is: public bool Intersects(Rectanglef rectangle) { return this.Left < rectangle.Right && this.Right > rectangle.Left && this.Top < rectangle.Bottom && this.Bottom > rectangle.Top; } public bool IntersectsAny(params Rectanglef[] rectangles) { for (int i = 0; i < rectangles.Length; i++) { if (this.Left < rectangles[i].Right && this.Right > rectangles[i].Left && this.Top < rectangles[i].Bottom && this.Bottom > rectangles[i].Top) return true; } return false; } and here is how I use it in the update function of my player : public void Update(GameTime gameTime) { Rectanglef nextPosX = new Rectanglef(AABB.X, AABB.Y, AABB.Width, AABB.Height); Rectanglef nextPosY; if (Input.Key(Key.Left)) nextPosX.X--; if (Input.Key(Key.Right)) nextPosX.X++; bool xFree = !nextPosX.IntersectsAny(Boxes.ToArray()); if (xFree) nextPosY = new Rectanglef(nextPosX.X, nextPosX.Y, nextPosX.Width, nextPosX.Height); else nextPosY = new Rectanglef(AABB.X, AABB.Y, AABB.Width, AABB.Height); if (Input.Key(Key.Up)) nextPosY.Y--; if (Input.Key(Key.Down)) nextPosY.Y++; bool yFree = !nextPosY.IntersectsAny(Boxes.ToArray()); if (yFree) AABB = nextPosY; else if (xFree) AABB = nextPosX; } What I'm having trouble with, is a system where I can give float values to my movement and make it so there's a smooth acceleration. Do I have to retrieve the collision rectangle (the rectangle created by the other two colliding)? or should I do some sort of vector and go along this axis until I reach the collision? Thanks a lot!

  Read the article

• Cloud Computing Business Benefits

  - by workflowman

  If you have been living under a rock for the past year, you wouldn't have heard about cloud computing. Cloud computing is a loose term that describes anything that is hosted in data centers and accessed via the internet. It is normally associated with developers who draw clouds in diagrams indicating where services or how systems communicate with each other. Cloud computing also incorporates such well-known trends as Web 2.0 and Software as a Service (SaaS) and more recently Infrastructure as a Service (IaaS) and Platform as a Service (PaaS). Its aim is to change the way we compute, moving from traditional desktop and on-premises servers to services and resources that are hosted in the cloud.  Benefits of Cloud Computing  There are clearly benefits in building applications using cloud computing, some of which are listed here:  Zero up- front investment:  Delivering a large-scale system costs a fortune in both time and money. Often IT departments are split into hardware/network and software services. The hardware team provisions servers and so forth under the requirements of the software team. Often the hardware team has a different budget that requires approval. Although hardware and software management are two separate disciplines, sometimes what happens is developers are given the task to estimate CPU cycles, disk space, and so forth, which ends up in underutilized servers.  Usage-based costing:  You pay for what you use, no more, no less, because you never actually own the server. This is similar to car leasing, where in the long run you get a new car every three years and maintenance is never a worry.  Potential for shrinking the processing time:  If processes are split over multiple machines, parallel processing is performed, which decreases processing time.  More office space:  Walk into most offices, and guaranteed you will find a medium- sized room dedicated to servers.  Efficient resource utilization:  The resource utilization is handed by a centralized cloud administrator who is in charge of deciding exactly the right amount of resources for a system. This takes the task away from local administrators, who have to regularly monitor these servers.  Just-in-time infrastructure:  If your system is a success and needs to scale to meet demand, this can cause further time delays or a slow- performing service. Cloud computing solves this because you can add more resources at any time.  Lower environmental impact:  If servers are centralized, potentially an environment initiative is more likely to succeed. As an example, if servers are placed in sunny or windy parts of the world, then why not use these resources to power those servers?  Lower costs:  Unfortunately, this is one point that administrators will not like. If you have people administrating your e-mail server and network along with support staff doing other cloud-based tasks, this workforce can be reduced. This saves costs, though it also reduces jobs.

  Read the article

• SSMS Tools Pack 3.0 is out. Full SSMS 2014 support and improved features.

  - by Mladen Prajdic

  With version 3.0 the SSMS 2014 is fully supported. Since this is a new major version you'll eventually need a new license. Please check the EULA to see when. As a thank you for your patience with this release, everyone that bought the SSMS Tools Pack after April 1st, the release date of SQL Server 2014, will receive a free upgrade. You won't have to do anything for this to take effect. First thing you'll notice is that the UI has been completely changed. It's more in line with SSMS and looks less web-like. Also the core has been updated and rewritten in some places to be better suited for future features. Major improvements for this release are: Window Connection Coloring Something a lot of people have asked me over the last 2 years is if there's a way to color the tab of the window itself. I'm very glad to say that now it is. In SSMS 2012 and higher the actual query window tab is also colored at the top border with the same color as the already existing strip making it much easier to see to which server your query window is connected to even when a window is not focused. To make it even better, you can not also specify the desired color based on the database name and not just the server name. This makes is useful for production environments where you need to be careful in which database you run your queries in. Format SQL The format SQL core was rewritten so it'll be easier to improve it in future versions. New improvement is the ability to terminate SQL statements with semicolons. This is available only in SSMS 2012 and up. Execution Plan Analyzer A big request was to implement the Problems and Solutions tooltip as a window that you can copy the text from. This is now available. You can move the window around and copy text from it. It's a small improvement but better stuff will come. SQL History Current Window History has been improved with faster search and now also shows the color of the server/database it was ran against. This is very helpful if you change your connection in the same query window making it clear which server/database you ran query on. The option to Force Save the history has been added. This is a menu item that flushes the execution and tab content history save buffers to disk. SQL Snippets Added an option to generate snippet from selected SQL text on right click menu. Run script on multiple databases Configurable database groups that you can save and reuse were added. You can create groups of preselected databases to choose from for each server. This makes repetitive tasks much easier New small team licensing option A lot of requests came in for 1 computer, Unlimited VMs option so now it's here. Hope it serves you well.

  Read the article

• A Simple Entity Tagger

  - by Elton Stoneman

  In the REST world, ETags are your gateway to performance boosts by letting clients cache responses. In the non-REST world, you may also want to add an ETag to an entity definition inside a traditional service contract – think of a scenario where a consumer persists its own representation of your entity, and wants to keep it in sync. Rather than load every entity by ID and check for changes, the consumer can send in a set of linked IDs and ETags, and you can return only the entities where the current ETag is different from the consumer’s version.  If your entity is a projection from various sources, you may not have a persistent ETag, so you need an efficient way to generate an ETag which is deterministic, so an entity with the same state always generates the same ETag. I have an implementation for a generic ETag generator on GitHub here: EntityTagger code sample. The essence is simple - we get the entity, serialize it and build a hash from the serialized value. Any changes to either the state or the structure of the entity will result in a different hash. To use it, just call SetETag, passing your populated object and a Func<> which acts as an accessor to the ETag property: EntityTagger.SetETag(user, x => x.ETag); The implementation is all in at 80 lines of code, which is all pretty straightforward: var eTagProperty = AsPropertyInfo(eTagPropertyAccessor); var originalETag = eTagProperty.GetValue(entity, null); try { ResetETag(entity, eTagPropertyAccessor); string json; var serializer = new DataContractJsonSerializer(entity.GetType()); using (var stream = new MemoryStream()) { serializer.WriteObject(stream, entity); json = Encoding.UTF8.GetString(stream.GetBuffer(), 0, (int)stream.Length); } var guid = GetDeterministicGuid(json); eTagProperty.SetValue(entity, guid.ToString(), null); //... There are a couple of helper methods to check if the object has changed since the ETag value was last set, and to reset the ETag. This implementation uses JSON to do the serializing rather than XML. Benefit - should be marginally more efficient as your hashing a much smaller serialized string; downside, JSON doesn't include namespaces or class names at the root level, so if you have two classes with the exact same structure but different names, then instances which have the same content will have the same ETag. You may want that behaviour, but change to use the XML DataContractSerializer if you think that will be an issue. If you can persist the ETag somewhere, it will save you server processing to load up the entity, but that will only apply to scenarios where you can reliably invalidate your ETag (e.g. if you control all the entry points where entity contents can be updated, then you can calculate and persist the new ETag with each update).

  Read the article

• [EF + Oracle] Inserting Data (Sequences) (2/2)

  - by JTorrecilla

  Prologue In the previous chapter we have see how to create DB records with EF, now we are going to Some Questions about Oracle.   ORACLE One characteristic from SQL Server that differs from Oracle is “Identity”. To all that has not worked with SQL Server, this property, that applies to Integer Columns, lets indicate that there is auto increment columns, by that way it will be filled automatically, without writing it on the insert statement. In EF with SQL Server, the properties whose match with Identity columns, will be filled after invoking SaveChanges method. In Oracle DB, there is no Identity Property, but there is something similar. Sequences Sequences are DB objects, that allow to create auto increment, but there are not related directly to a Table. The syntax is as follows: name, min value, max value and begin value. 1: CREATE SEQUENCE nombre_secuencia 2: INCREMENT BY numero_incremento 3: START WITH numero_por_el_que_empezara 4: MAXVALUE valor_maximo | NOMAXVALUE 5: MINVALUE valor_minimo | NOMINVALUE 6: CYCLE | NOCYCLE 7: ORDER | NOORDER 8:    How to get sequence value? To obtain the next val from the sequence: 1: SELECT nb_secuencia.Nextval 2: From Dual Due to there is no direct way to indicate that a column is related to a sequence, there is several ways to imitate the behavior: Use a Trigger (DB), Use Stored Procedures or Functions(…) or my particularly option. EF model, only, imports Table Objects, Stored Procedures or Functions, but not sequences. By that, I decide to create my own extension Method to invoke Next Val from a sequence: 1: public static class EFSequence 2: { 3: public static int GetNextValue(this ObjectContext contexto, string SequenceName) 4: { 5: string Connection = ConfigurationManager.ConnectionStrings["JTorrecillaEntities2"].ConnectionString; 6: Connection=Connection.Substring(Connection.IndexOf(@"connection string=")+19); 7: Connection = Connection.Remove(Connection.Length - 1, 1); 8: using (IDbConnection con = new Oracle.DataAccess.Client.OracleConnection(Connection)) 9: { 10: using (IDbCommand cmd = con.CreateCommand()) 11: { 12: con.Open(); 13: cmd.CommandText = String.Format("Select {0}.nextval from DUAL", SequenceName); 14: return Convert.ToInt32(cmd.ExecuteScalar()); 15: } 16: } 17:  18: } 19: } This Object Context’s extension method are going to invoke a query with the Sequence indicated by parameter. It takes the connection strings from the App settings, removing the meta data, that was created by VS when generated the EF model. And then, returns the next value from the Sequence. The next value of a Sequence is unique, by that, when some concurrent users are going to create records in the DB using the sequence will not get duplicates. This is my own implementation, I know that it could be several ways to do and better ways. If I find any other way, I promise to post it. To use the example is needed to add a reference to the Oracle (ODP.NET) dll.

  Read the article

< Previous Page | 616 617 618 619 620 621 622 623 624 625 626 627  | Next Page >