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  • Multiple Audio Issues

    - by Lerp
    I am having issues with my audio on Ubuntu 12.04, I will try and give as much detail as possible so sorry if there's too much detail. The Problem Audio plays from both speakers and headphone regardless of what connector I choose and regardless of the profile I use. The microphone is constantly being played through headphones & speakers. The headphone audio is extremely quiet but plays from both ears when I select "Headphones" for the connector in Sound Settings. The headphone audio only plays from one ear and is quiet (but not as quiet as above) when I select "Analogue Output" for the connector in Sound Settings. I can only select "Headphones" as the connector in Sound Settings if I set the profile to either "Analogue Stereo Output/Duplex", all others only allow me to choose "Analogue Output" for the connector. Despite the headphone sound issues, the speaker sound is fine apart from the fact that I am not able to select which output is used, they just both play. My headphone and microphone are plugged into the front and my speakers are plugged into the back. What I have tried I have put everything in alsamixer to 100 apart from "Front Mic Boost" which I have set to 0. Command Output aplay -l **** List of PLAYBACK Hardware Devices **** card 0: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog] Subdevices: 0/1 Subdevice #0: subdevice #0 card 0: Intel [HDA Intel], device 1: AD198x Digital [AD198x Digital] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: Intel [HDA Intel], device 2: AD198x Headphone [AD198x Headphone] Subdevices: 1/1 Subdevice #0: subdevice #0 arecord -l **** List of CAPTURE Hardware Devices **** card 0: Intel [HDA Intel], device 0: AD198x Analog [AD198x Analog] Subdevices: 2/3 Subdevice #0: subdevice #0 Subdevice #1: subdevice #1 Subdevice #2: subdevice #2 cat /proc/asound/cards 0 [Intel ]: HDA-Intel - HDA Intel HDA Intel at 0xf7ff8000 irq 70 cat /proc/asound/modules 0 snd_hda_intel cat /proc/asound/card*/codec* | grep "Codec" Codec: Analog Devices AD1989B cat /etc/modprobe.d/alsa-base.conf # autoloader aliases install sound-slot-0 /sbin/modprobe snd-card-0 install sound-slot-1 /sbin/modprobe snd-card-1 install sound-slot-2 /sbin/modprobe snd-card-2 install sound-slot-3 /sbin/modprobe snd-card-3 install sound-slot-4 /sbin/modprobe snd-card-4 install sound-slot-5 /sbin/modprobe snd-card-5 install sound-slot-6 /sbin/modprobe snd-card-6 install sound-slot-7 /sbin/modprobe snd-card-7 # Cause optional modules to be loaded above generic modules install snd /sbin/modprobe --ignore-install snd $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-ioctl32 ; /sbin/modprobe --quiet --use-blacklist snd-seq ; } # # Workaround at bug #499695 (reverted in Ubuntu see LP #319505) install snd-pcm /sbin/modprobe --ignore-install snd-pcm $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-pcm-oss ; : ; } install snd-mixer /sbin/modprobe --ignore-install snd-mixer $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-mixer-oss ; : ; } install snd-seq /sbin/modprobe --ignore-install snd-seq $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; /sbin/modprobe --quiet --use-blacklist snd-seq-oss ; : ; } # install snd-rawmidi /sbin/modprobe --ignore-install snd-rawmidi $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; : ; } # Cause optional modules to be loaded above sound card driver modules install snd-emu10k1 /sbin/modprobe --ignore-install snd-emu10k1 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-emu10k1-synth ; } install snd-via82xx /sbin/modprobe --ignore-install snd-via82xx $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq ; } # Load saa7134-alsa instead of saa7134 (which gets dragged in by it anyway) install saa7134 /sbin/modprobe --ignore-install saa7134 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist saa7134-alsa ; : ; } # Prevent abnormal drivers from grabbing index 0 options bt87x index=-2 options cx88_alsa index=-2 options saa7134-alsa index=-2 options snd-atiixp-modem index=-2 options snd-intel8x0m index=-2 options snd-via82xx-modem index=-2 options snd-usb-audio index=-2 options snd-usb-caiaq index=-2 options snd-usb-ua101 index=-2 options snd-usb-us122l index=-2 options snd-usb-usx2y index=-2 # Ubuntu #62691, enable MPU for snd-cmipci options snd-cmipci mpu_port=0x330 fm_port=0x388 # Keep snd-pcsp from being loaded as first soundcard options snd-pcsp index=-2 # Keep snd-usb-audio from beeing loaded as first soundcard options snd-usb-audio index=-2 Hopefully I have provided enough information, I will happily provide anymore information needed. Thank you. Update Reinstalling alsa-base and pulseaudio fixed the headphone issues I was having.

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  • A Patent for Workload Management Based on Service Level Objectives

    - by jsavit
    I'm very pleased to announce that after a tiny :-) wait of about 5 years, my patent application for a workload manager was finally approved. Background Many operating systems have a resource manager which lets you control machine resources. For example, Solaris provides controls for CPU with several options: shares for proportional CPU allocation. If you have twice as many shares as me, and we are competing for CPU, you'll get about twice as many CPU cycles), dedicated CPU allocation in which a number of CPUs are exclusively dedicated to an application's use. You can say that a zone or project "owns" 8 CPUs on a 32 CPU machine, for example. And, capped CPU in which you specify the upper bound, or cap, of how much CPU an application gets. For example, you can throttle an application to 0.125 of a CPU. (This isn't meant to be an exhaustive list of Solaris RM controls.) Workload management Useful as that is (and tragic that some other operating systems have little resource management and isolation, and frighten people into running only 1 app per OS instance - and wastefully size every server for the peak workload it might experience) that's not really workload management. With resource management one controls the resources, and hope that's enough to meet application service objectives. In fact, we hold resource distribution constant, see if that was good enough, and adjust resource distribution if that didn't meet service level objectives. Here's an example of what happens today: Let's try 30% dedicated CPU. Not enough? Let's try 80% Oh, that's too much, and we're achieving much better response time than the objective, but other workloads are starving. Let's back that off and try again. It's not the process I object to - it's that we to often do this manually. Worse, we sometimes identify and adjust the wrong resource and fiddle with that to no useful result. Back in my days as a customer managing large systems, one of my users would call me up to beg for a "CPU boost": Me: "it won't make any difference - there's plenty of spare CPU to be had, and your application is completely I/O bound." User: "Please do it anyway." Me: "oh, all right, but it won't do you any good." (I did, because he was a friend, but it didn't help.) Prior art There are some operating environments that take a stab about workload management (rather than resource management) but I find them lacking. I know of one that uses synthetic "service units" composed of the sum of CPU, I/O and memory allocations multiplied by weighting factors. A workload is set to make a target rate of service units consumed per second. But this seems to be missing a key point: what is the relationship between artificial 'service units' and actually meeting a throughput or response time objective? What if I get plenty of one of the components (so am getting enough service units), but not enough of the resource whose needed to remove the bottleneck? Actual workload management That's not really the answer either. What is needed is to specify a workload's service levels in terms of externally visible metrics that are meaningful to a business, such as response times or transactions per second, and have the workload manager figure out which resources are not being adequately provided, and then adjust it as needed. If an application is not meeting its service level objectives and the reason is that it's not getting enough CPU cycles, adjust its CPU resource accordingly. If the reason is that the application isn't getting enough RAM to keep its working set in memory, then adjust its RAM assignment appropriately so it stops swapping. Simple idea, but that's a task we keep dumping on system administrators. In other words - don't hold the number of CPU shares constant and watch the achievement of service level vary. Instead, hold the service level constant, and dynamically adjust the number of CPU shares (or amount of other resources like RAM or I/O bandwidth) in order to meet the objective. Instrumenting non-instrumented applications There's one little problem here: how do I measure application performance in a way relating to a service level. I don't want to do it based on internal resources like number of CPU seconds it received per minute - We need to make resource decisions based on externally visible and meaningful measures of performance, not synthetic items or internal resource counters. If I have a way of marking the beginning and end of a transaction, I can then measure whether or not the application is meeting an objective based on it. If I can observe the delay factors for an application, I can see which resource shortages are slowing an application enough to keep it from meeting its objectives. I can then adjust resource allocations to relieve those shortages. Fortunately, Solaris provides facilities for both marking application progress and determining what factors cause application latency. The Solaris DTrace facility let's me introspect on application behavior: in particular I can see events like "receive a web hit" and "respond to that web hit" so I can get transaction rate and response time. DTrace (and tools like prstat) let me see where latency is being added to an application, so I know which resource to adjust. Summary After a delay of a mere few years, I am the proud creator of a patent (advice to anyone interested in going through the process: don't hold your breath!). The fundamental idea is fairly simple: instead of holding resource constant and suffering variable levels of success meeting service level objectives, properly characterise the service level objective in meaningful terms, instrument the application to see if it's meeting the objective, and then have a workload manager change resource allocations to remove delays preventing service level attainment. I've done it by hand for a long time - I think that's what a computer should do for me.

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  • Why bother writing an Windows 8 app?

    - by Dennis Vroegop
    So you want to know more about development for Window 8. Great! There are lots of reasons you should be excited about this. Since I don’t know why YOU are interested in this, I’ll make a list of reasons people can choose from. (as a side note: whenever I talk about Win8 development I am referring to the Metro Style / WinRt side of things. Apps for the ‘classic’ desktop side of Win8 on Intel are business as usual…) So… Why would you care about making an app for Windows 8? 1. It’s cool. Let’s not beat around the bush: if you like development for a hobby then you’ll love to work on this new platform. You can create apps in a relative short time (short time as in compared to writing a new CRM system) and that makes it great for a hobby product. 2. You’ll stand out. Hey, we all need an ego boost every now and then. We all need to feel special. So if you can manage to be one of the first to have you app in the Store then you’ll likely to be noticed. Just close your eyes for a moment and image you standing in a bar. It’s crowded, and then you casually say “Oh yeah, I just had my app certified and it’s in the Win8 store now”. People will stop talking, will offer you drinks and beautiful women / gorgeous man / furry creatures from Alpha Centauri (whatever your preferences are) will propose. Or maybe not. Anyway…. 3. Make some cash! IDC predicts there will be about 350,000,000 Windows 8 licenses sold in the next year. Think about that number. 350,000,000. And they all have access to the Store. Where you’re app will be. With one little click they can select it, download and somehow magically $1.00 or $2.00 from their bank account is transferred to yours. Now, I am not saying that all of those people will download and buy your app but what if only 1% of them did? Remember: there aren’t that many apps available yet….. 4. Learn. Creating new small apps is a great way to learn new stuff. Yes, you could read about it (on this blog for instance) but the only way to learn something is to do it. So be prepared for the future and learn something new by doing it.Write an app! Now! 5. The biggie (for me at least): it’s fun. Even if you remove the points above it’s still fun to write for these devices and this platform. Now some of you will say : “But why not write a great app for IOS or Android?” I think this is a valid question. Of course the novelty of the platform wears out and points 2 and 3 from above list will not be as relevant as it is today. But still 1 4 and 5 remain. And don’t forget: if you already work on the Microsoft platform it’s not that hard to learn this new Win8 stuff. If you have done some XAML development (be it WPF or Silverlight) you are almost there in becoming a good Win8 developer. So you’ll be more productive much sooner than when you have to learn Objective C or Java. Even if you’re a HTML / Javascript developer (I say developer here, not designer) you’ll be up to speed on Win8 development pretty soon. Yes, you, that funky Web Developer who lives and breathes HTML5, CSS3 and JavaScript / Node.Js / JQuery: you too can be a Win8 developer. A first class Win8 developer! So.. Download the stuff you need from http://dev.windows.com install Windows 8 and Visual Studio 12 and by the time you’re ready I’ll be working on the next article: how to do all this? Happy coding!

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  • From the Classroom to the Boardroom

    - by Maria Sandu
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Pens and Paper...these are the only things being a student and being a graduate / professional have in common. Walking in to the offices of Oracle South Africa as a graduate the first thing you notice is how polished and sleek all the people who work here look. 80% of the ladies wear sky-scraper heels and walk with the greatest grace. This was the first of many rude awakenings to remind me that I am no longer a student but a graduate. My first struggle was having to wake up at wee hours of the morning to prepare for work. As a student going to class was almost an optional thing, if you missed a morning class you could always attend an evening class to make up for it or simply attend with another group. But in the workplace, you HAVE to show up every single morning at the same time, with no option of coming in when it suits you and there is definitely no coming in with the evening class/shift. As a student, the earliest hour I ever woke up was 7:00am, anything earlier than that was considered inhumane torture. My reason for waking up every morning as a student was “you have a degree to go get” but as a graduate having to go to work I have to say to myself “here’s to a new day of learning and growing”. My second struggle has come in having to change my beloved wardrobe. Everyone who knows me knows how passionate I am about fashion and shopping. For me Shopping is a BASIC HUMAN RIGHT, that should not be messed with. Therefore it was with great sadness that I swopped my rippled skinny jeans for pin-striped formal pants, my long chandelier earrings for simple studs, my flat shoes for heels, my sheer blouses for crisp white shirts, even my beloved wild hair had to make way for a simple ponytail. Our looks as ladies also came under great scrutiny, we had to acquaint ourselves with some serious grooming tools: the mascara, blush, lip-gloss, blush, a touch of lipstick and a manicure set. Language was a struggle of its own as well. Being a student you learn to relate to your peers in a informal way. In the workplace you have to address everyone with the same respect, including your peers. Words like “Hey buddy” had to make way for “good morning friend”. The month long winter school holiday was one of the things I looked forward to as a student. This was a time where we got to be at home and avoid the coldest month of the year, July. It was the most amazing thing ever, just sleeping and snuggling up to all sorts of warm things but sadly it is now a thing of the past. It is currently winter in South Africa and going to work has become the most unfashionable thing with all the jackets, boots, scarves and gloves. But summer is coming and I will miss those holidays too. As a student the school holidays were like a gift for us to catch a break and not think for a while which was why it was imaginable how someone would go on for the entire year without a break, with only the promise of a mere 21 days annual leave!! Right now I am sure we are all looking forward to taking that annual leave when the time is right. The worst rude awakening I must say, has to be presenting in front of clients and managers. As a student you have the same class mates for almost four years therefore presenting in front of them becomes the norm over the years and your lecturer will always go gently on you. What they don’t tell you at University is that in the real world, time is money and clients pay money to see you present therefore there is no room for error. Clients are not there to give you a score and boost your ego, they expect nothing less than 100% and they will let you know without a second thought. For a graduate this can feel like you are being fed to the sharks, you either get eaten or you swim for your life. At the end of the day, it is all an experience that is meant to groom us into better professional and make us a part of the Red Team. All the sacrifices are worth it and they lead us to being better and more polished professionals. So if you are interested in joining the ECEMEA Sales and Presales Internship Programme, please have a look at http://campus.oracle.com for more information and for our latest vacancies and internships. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Key Windows Phone Development Concepts

    - by Tim Murphy
    As I am doing more development in and out of the enterprise arena for Windows Phone I decide I would study for the 70-599 test.  I generally take certification tests as a way to force me to dig deeper into a technology.  Between the development and studying I decided it would be good to put a post together of key development features in Windows Phone 7 environment.  Contrary to popular belief the launch of Windows Phone 8 will not obsolete Windows Phone 7 development.  With the launch of 7.8 coming shortly and people who will remain on 7.X for the foreseeable future there are still consumers needing these apps so don’t throw out the baby with the bath water. PhoneApplicationService This is a class that every Windows Phone developer needs to become familiar with.  When it comes to application state this is your go to repository.  It also contains events that help with management of your application’s lifecycle.  You can access it like the following code sample. 1: PhoneApplicationService.Current.State["ValidUser"] = userResult; DeviceNetworkInformation This class allows you to determine the connectivity of the device and be notified when something changes with that connectivity.  If you are making web service calls you will want to check here before firing off. I have found that this class doesn’t actually work very well for determining if you have internet access.  You are better of using the following code where IsConnectedToInternet is an App level property. private void Application_Launching(object sender, LaunchingEventArgs e){ // Validate user access if (Microsoft.Phone.Net.NetworkInformation.NetworkInterface.NetworkInterfaceType != Microsoft.Phone.Net.NetworkInformation.NetworkInterfaceType.None) { IsConnectedToInternet = true; } else { IsConnectedToInternet = false; } NetworkChange.NetworkAddressChanged += new NetworkAddressChangedEventHandler(NetworkChange_NetworkAddressChanged);}void NetworkChange_NetworkAddressChanged(object sender, EventArgs e){ IsConnectedToInternet = (Microsoft.Phone.Net.NetworkInformation.NetworkInterface.NetworkInterfaceType != Microsoft.Phone.Net.NetworkInformation.NetworkInterfaceType.None);} Push Notification Push notification allows your application to receive notifications in a way that reduces the application’s power needs. This MSDN article is a good place to get the basics of push notification, but you can see the essential concept in the diagram below.  There are three types of push notification: toast, Tile and raw.  The first two work regardless of the state of the application where as raw messages are discarded if your application is not running.   Live Tiles Live tiles are one of the main differentiators of the Windows Phone platform.  They allow users to find information at a glance from their start screen without navigating into individual apps.  Knowing how to implement them can be a great boost to the attractiveness of your application. The simplest step-by-step explanation for creating live tiles is here. Local Database While your application really only has Isolated Storage as a data store there are some ways of giving you database functionality to develop against.  There are a number of open source ORM style solutions.  Probably the best and most native way I have found is to use LINQ to SQL.  It does take a significant amount of setup, but the ease of use once it is configured is worth the cost.  Rather than repeat the full concepts here I will point you to a post that I wrote previously. Tasks (Bing, Email) Leveraging built in features of the Windows Phone platform is an easy way to add functionality that would be expensive to develop on your own.  The classes that you need to make yourself familiar with are BingMapsDirectionsTask and EmailComposeTask.  This will allow your application to supply directions and give the user an email path to relay information to friends and associates. Event model Because of the ability for users to switch quickly to switch to other apps or the home screen is just one reason why knowing the Windows Phone event model is important.  You need to be able to save data so that if a user gets a phone call they can come back to exactly where they were in your application.  This means that you will need to handle such events as Launching, Activated, Deactivated and Closing at an application level.  You will probably also want to get familiar with the OnNavigatedTo and OnNavigatedFrom events at the page level.  These will give you an opportunity to save data as a user navigates through your app. Summary This is just a small portion of the concepts that you will use while building Windows Phone apps, but these are some of the most critical.  With the launch of Windows Phone 8 this list will probably expand.  Take the time to investigate these topics further and try them out in your apps. del.icio.us Tags: Windows Phone 7,Windows Phone,WP7,Software Development,70-599

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  • C++ strongly typed typedef

    - by Kian
    I've been trying to think of a way of declaring strongly typed typedefs, to catch a certain class of bugs in the compilation stage. It's often the case that I'll typedef an int into several types of ids, or a vector to position or velocity: typedef int EntityID; typedef int ModelID; typedef Vector3 Position; typedef Vector3 Velocity; This can make the intent of code more clear, but after a long night of coding one might make silly mistakes like comparing different kinds of ids, or adding a position to a velocity perhaps. EntityID eID; ModelID mID; if ( eID == mID ) // <- Compiler sees nothing wrong { /*bug*/ } Position p; Velocity v; Position newP = p + v; // bug, meant p + v*s but compiler sees nothing wrong Unfortunately, suggestions I've found for strongly typed typedefs include using boost, which at least for me isn't a possibility (I do have c++11 at least). So after a bit of thinking, I came upon this idea, and wanted to run it by someone. First, you declare the base type as a template. The template parameter isn't used for anything in the definition, however: template < typename T > class IDType { unsigned int m_id; public: IDType( unsigned int const& i_id ): m_id {i_id} {}; friend bool operator==<T>( IDType<T> const& i_lhs, IDType<T> const& i_rhs ); }; Friend functions actually need to be forward declared before the class definition, which requires a forward declaration of the template class. We then define all the members for the base type, just remembering that it's a template class. Finally, when we want to use it, we typedef it as: class EntityT; typedef IDType<EntityT> EntityID; class ModelT; typedef IDType<ModelT> ModelID; The types are now entirely separate. Functions that take an EntityID will throw a compiler error if you try to feed them a ModelID instead, for example. Aside from having to declare the base types as templates, with the issues that entails, it's also fairly compact. I was hoping anyone had comments or critiques about this idea? One issue that came to mind while writing this, in the case of positions and velocities for example, would be that I can't convert between types as freely as before. Where before multiplying a vector by a scalar would give another vector, so I could do: typedef float Time; typedef Vector3 Position; typedef Vector3 Velocity; Time t = 1.0f; Position p = { 0.0f }; Velocity v = { 1.0f, 0.0f, 0.0f }; Position newP = p + v*t; With my strongly typed typedef I'd have to tell the compiler that multypling a Velocity by a Time results in a Position. class TimeT; typedef Float<TimeT> Time; class PositionT; typedef Vector3<PositionT> Position; class VelocityT; typedef Vector3<VelocityT> Velocity; Time t = 1.0f; Position p = { 0.0f }; Velocity v = { 1.0f, 0.0f, 0.0f }; Position newP = p + v*t; // Compiler error To solve this, I think I'd have to specialize every conversion explicitly, which can be kind of a bother. On the other hand, this limitation can help prevent other kinds of errors (say, multiplying a Velocity by a Distance, perhaps, which wouldn't make sense in this domain). So I'm torn, and wondering if people have any opinions on my original issue, or my approach to solving it.

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  • vector iterator not dereferencable at runtime on a vector<vector<vector<A*>*>*>

    - by marouanebj
    Hi, I have this destructor that create error at runtime "vector iterator not dereferencable". The gridMatrix is a std::vector<std::vector<std::vector<AtomsCell< Atom<T> * > * > * > * > I added the typename and also the typedef but I still have the error. I will move for this idea of vect of vect* of vect* to use boost::multi_array I think, but still I want to understand were this is wrong. /// @brief destructor ~AtomsGrid(void) { // free all the memory for all the pointers inside gridMatrix (all except the Atom<T>* ) //typedef typename ::value_type value_type; typedef std::vector<AtomsCell< Atom<T>* >*> std_vectorOfAtomsCell; typedef std::vector<std_vectorOfAtomsCell*> std_vectorOfVectorOfAtomsCell; std_vectorOfAtomsCell* vectorOfAtomsCell; std_vectorOfVectorOfAtomsCell* vectorOfVecOfAtomsCell; typename std_vectorOfVectorOfAtomsCell::iterator itSecond; typename std_vectorOfVectorOfAtomsCell::reverse_iterator reverseItSecond; typename std::vector<std_vectorOfVectorOfAtomsCell*>::iterator itFirst; //typename std::vector<AtomsCell< Atom<T>* >*>* vectorOfAtomsCell; //typename std::vector<std::vector<AtomsCell< Atom<T>* >*>*>* vectorOfVecOfAtomsCell; //typename std::vector<std::vector<AtomsCell< Atom<T>* >*>*>::iterator itSecond; //typename std::vector<std::vector<AtomsCell< Atom<T>* >*>*>::reverse_iterator reverseItSecond; //typename std::vector<std::vector<std::vector<AtomsCell< Atom<T>* >*>*>*>::iterator itFirst; for (itFirst = gridMatrix.begin(); itFirst != gridMatrix.end(); ++itFirst) { vectorOfVecOfAtomsCell = (*itFirst); while (!vectorOfVecOfAtomsCell->empty()) { reverseItSecond = vectorOfVecOfAtomsCell->rbegin(); itSecond = vectorOfVecOfAtomsCell->rbegin().base(); vectorOfAtomsCell = (*itSecond); // ERROR during run: "vector iterator not dereferencable" // I think the ERROR is because I need some typedef typename or template ???!!! // the error seems here event at itFirst //fr_Myit_Utils::vectorElementDeleter(*vectorOfAtomsCell); //vectorOfVecOfAtomsCell->pop_back(); } } fr_Myit_Utils::vectorElementDeleter(gridMatrix); } If someone want the full code that create the error I'm happy to give it but I do not think we can attach file in the forum. BUT still its is not very big so if you want it I can copy past it here. Thanks

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  • What output and recording ports does the Java Sound API find on your computer?

    - by Dave Carpeneto
    Hi all - I'm working with the Java Sound API, and it turns out if I want to adjust recording volumes I need to model the hardware that the OS exposes to Java. Turns out there's a lot of variety in what's presented. Because of this I'm humbly asking that anyone able to help me run the following on their computer and post back the results so that I can get an idea of what's out there. A thanks in advance to anyone that can assist :-) import javax.sound.sampled.*; public class SoundAudit { public static void main(String[] args) { try { System.out.println("OS: "+System.getProperty("os.name")+" "+ System.getProperty("os.version")+"/"+ System.getProperty("os.arch")+"\nJava: "+ System.getProperty("java.version")+" ("+ System.getProperty("java.vendor")+")\n"); for (Mixer.Info thisMixerInfo : AudioSystem.getMixerInfo()) { System.out.println("Mixer: "+thisMixerInfo.getDescription()+ " ["+thisMixerInfo.getName()+"]"); Mixer thisMixer = AudioSystem.getMixer(thisMixerInfo); for (Line.Info thisLineInfo:thisMixer.getSourceLineInfo()) { if (thisLineInfo.getLineClass().getName().equals( "javax.sound.sampled.Port")) { Line thisLine = thisMixer.getLine(thisLineInfo); thisLine.open(); System.out.println(" Source Port: " +thisLineInfo.toString()); for (Control thisControl : thisLine.getControls()) { System.out.println(AnalyzeControl(thisControl));} thisLine.close();}} for (Line.Info thisLineInfo:thisMixer.getTargetLineInfo()) { if (thisLineInfo.getLineClass().getName().equals( "javax.sound.sampled.Port")) { Line thisLine = thisMixer.getLine(thisLineInfo); thisLine.open(); System.out.println(" Target Port: " +thisLineInfo.toString()); for (Control thisControl : thisLine.getControls()) { System.out.println(AnalyzeControl(thisControl));} thisLine.close();}}} } catch (Exception e) {e.printStackTrace();}} public static String AnalyzeControl(Control thisControl) { String type = thisControl.getType().toString(); if (thisControl instanceof BooleanControl) { return " Control: "+type+" (boolean)"; } if (thisControl instanceof CompoundControl) { System.out.println(" Control: "+type+ " (compound - values below)"); String toReturn = ""; for (Control children: ((CompoundControl)thisControl).getMemberControls()) { toReturn+=" "+AnalyzeControl(children)+"\n";} return toReturn.substring(0, toReturn.length()-1);} if (thisControl instanceof EnumControl) { return " Control:"+type+" (enum: "+thisControl.toString()+")";} if (thisControl instanceof FloatControl) { return " Control: "+type+" (float: from "+ ((FloatControl) thisControl).getMinimum()+" to "+ ((FloatControl) thisControl).getMaximum()+")";} return " Control: unknown type";} } All the application does is print out a line about the OS, a line about the JVM, and a few lines about the hardware found that may pertain to recording hardware. For example on my PC at work I get the following: OS: Windows XP 5.1/x86 Java: 1.6.0_07 (Sun Microsystems Inc.) Mixer: Direct Audio Device: DirectSound Playback [Primary Sound Driver] Mixer: Direct Audio Device: DirectSound Playback [SoundMAX HD Audio] Mixer: Direct Audio Device: DirectSound Capture [Primary Sound Capture Driver] Mixer: Direct Audio Device: DirectSound Capture [SoundMAX HD Audio] Mixer: Software mixer and synthesizer [Java Sound Audio Engine] Mixer: Port Mixer [Port SoundMAX HD Audio] Source Port: MICROPHONE source port Control: Microphone (compound - values below) Control: Select (boolean) Control: Microphone Boost (boolean) Control: Front panel microphone (boolean) Control: Volume (float: from 0.0 to 1.0) Source Port: LINE_IN source port Control: Line In (compound - values below) Control: Select (boolean) Control: Volume (float: from 0.0 to 1.0) Control: Balance (float: from -1.0 to 1.0)

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  • C# Monte Carlo Incremental Risk Calculation optimisation, random numbers, parallel execution

    - by m3ntat
    My current task is to optimise a Monte Carlo Simulation that calculates Capital Adequacy figures by region for a set of Obligors. It is running about 10 x too slow for where it will need to be in production and number or daily runs required. Additionally the granularity of the result figures will need to be improved down to desk possibly book level at some stage, the code I've been given is basically a prototype which is used by business units in a semi production capacity. The application is currently single threaded so I'll need to make it multi-threaded, may look at System.Threading.ThreadPool or the Microsoft Parallel Extensions library but I'm constrained to .NET 2 on the server at this bank so I may have to consider this guy's port, http://www.codeproject.com/KB/cs/aforge_parallel.aspx. I am trying my best to get them to upgrade to .NET 3.5 SP1 but it's a major exercise in an organisation of this size and might not be possible in my contract time frames. I've profiled the application using the trial of dotTrace (http://www.jetbrains.com/profiler). What other good profilers exist? Free ones? A lot of the execution time is spent generating uniform random numbers and then translating this to a normally distributed random number. They are using a C# Mersenne twister implementation. I am not sure where they got it or if it's the best way to go about this (or best implementation) to generate the uniform random numbers. Then this is translated to a normally distributed version for use in the calculation (I haven't delved into the translation code yet). Also what is the experience using the following? http://quantlib.org http://www.qlnet.org (C# port of quantlib) or http://www.boost.org Any alternatives you know of? I'm a C# developer so would prefer C#, but a wrapper to C++ shouldn't be a problem, should it? Maybe even faster leveraging the C++ implementations. I am thinking some of these libraries will have the fastest method to directly generate normally distributed random numbers, without the translation step. Also they may have some other functions that will be helpful in the subsequent calculations. Also the computer this is on is a quad core Opteron 275, 8 GB memory but Windows Server 2003 Enterprise 32 bit. Should I advise them to upgrade to a 64 bit OS? Any links to articles supporting this decision would really be appreciated. Anyway, any advice and help you may have is really appreciated.

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  • MySql multiple selects batching in .net

    - by Amith George
    I have a situation in my application. For each x-axis point in my chart, I am plotting 5 y-axis values. To calculate each of these 5 values, I need to make 4 different queries. Ie, for each x-axis point I need to fire 20 sql queries. Now, I need to plot 40 such points in the my chart. Its resulting in a pathetic performance where it takes close to a minute to get all the data back from the database. Each of 4 different queries consists of a join between 2 tables. One has only 6 rows. The other close to 10,000. Each of the 4 queries has different WHERE clauses, so they are different queries. For each point in the x-axis, only the values for the where clauses change. I have tried combining each of the 4 queries into one big string. Basically batch the four selects. These are again batched for each y-axis value. So, for each x-axis point, I am now firing one big command that consists of 20 different select statements. Technically, I should be experiencing a big performance boost, right? Instead of hitting the db 40x5x4 = 800 times, I am now hitting it just 40 times. But instead of taking 60 seconds, it taking 50-55 seconds... not much of a help. I am using MySql 5.1, and the 6.1 version of its .Net connector. What can I do to improve the performance? Edit: One of the 4 queries is as follows: SELECT SUM(TIME_TO_SEC(TIMEDIFF(T1.col2, T1.col1))* T2.col1 / (3600 *1000)) AS TotalTime FROM Table T1 JOIN Table T2 ON T1.col3 = T2.col3 WHERE T1.col4 = 'i' AND T1.col1 >= '2009-12-25 00:00:00' AND T1.col2 <= '2009-12-26 00:00:00'; The other 3 queries are similar, only the where clause changes slightly. This set of 4 queries is fired 5 times. The first 3 times against the join of table T1 and T2, passing in different values for col4. And the next two times against the join of table T3 and T2 passing in different values for col4. These 5 values are the y-axis values for a particular x-axis point. The data returned by all these queries is the same format. so, we tried doing a UNION ALL on all these queries. No substantial difference. One strange thing, however, after indexing the foreign key on the table T1 [while it contained over a lakh records], the queries were using the index, but they had become slower. At times, the queries would take double the time to return the data.

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  • Sysadmin 101: How can I figure out why my server crashes and monitor performance?

    - by bflora
    I have a Drupal-powered site that seems to have neverending performance problems. It was butt-slow about 5 months ago. I brought in some guys who installed nginx for anonymous visitors, ajaxified a few queries so they wouldn't fire during page load, and helped me find a few bottlenecks in the code. For about a month, the site was significantly faster, though not "fast" by any stretch of the word. Meanwhile, I'm now shelling out $400/month to Slicehost to host a site that gets less than 5,000/uniques a day. Yes, you read that right. Go Drupal. Recently the site started crashing again and is slow again. I can't afford to hire people to come in, study my code from top to bottom, and make changes that may or may not help anymore. And I can't afford to throw more hardware at the problem. So I need to figure out what the problem is myself. Questions: When apache crashes, is it possible to find out what caused it to crash? There has to be a way, right? If so, how can I do this? Is there software I can use that will tell me which process caused my server to die? (e.g. "Apache crashed because someone visited page X." or "Apache crashed because you were importing too many RSS items from feed X.") There's got to be a way to learn this, right? What's a good, noob-friendly way to monitor my current apache performance? My developer friends tell me to "just use Top, dude," but Top shows me a bunch of numbers without any context. I have no clue what qualifies as a bad number or a good number in Top, or which processes are relevant and which aren't. Are there any noob-friendly server monitoring tools out there? Ideally, I could have a page that would give me a color-coded indicator about how apache is performing and then show me a list of processes or pages that are sucking right now. This way, I could know when performance is bad and then what's causing it to be so bad. Why does PHP memory matter? My apparently has a 30MB memory foot print. Will it run faster if I bring that number down? Thanks for any advice. I spent a year or so trying to boost my advertising income so I could hire a contractor to solve my performance woes. I didn't want to have to learn all this sysadmin voodoo. I'm now resigned to the fact that might not have a choice.

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  • Segmentation fault in std function std::_Rb_tree_rebalance_for_erase ()

    - by Sarah
    I'm somewhat new to programming and am unsure how to deal with a segmentation fault that appears to be coming from a std function. I hope I'm doing something stupid (i.e., misusing a container), because I have no idea how to fix it. The precise error is Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address: 0x000000000000000c 0x00007fff8062b144 in std::_Rb_tree_rebalance_for_erase () (gdb) backtrace #0 0x00007fff8062b144 in std::_Rb_tree_rebalance_for_erase () #1 0x000000010000e593 in Simulation::runEpidSim (this=0x7fff5fbfcb20) at stl_tree.h:1263 #2 0x0000000100016078 in main () at main.cpp:43 The function that exits successfully just before the segmentation fault updates the contents of two containers. One is a boost::unordered_multimap called carriage; it contains one or more struct Infection objects that contain two doubles. The other container is of type std::multiset< Event, std::less< Event EventPQ called ce. It is full of Event structs. void Host::recover( int s, double recoverTime, EventPQ & ce ) { // Clearing all serotypes in carriage // and their associated recovery events in ce // and then updating susceptibility to each serotype double oldRecTime; int z; for ( InfectionMap::iterator itr = carriage.begin(); itr != carriage.end(); itr++ ) { z = itr->first; oldRecTime = (itr->second).recT; EventPQ::iterator epqItr = ce.find( Event(oldRecTime) ); assert( epqItr != ce.end() ); ce.erase( epqItr ); immune[ z ]++; } carriage.clear(); calcSusc(); // a function that edits an array cout << "Done with sync_recovery event." << endl; } The last cout << line appears immediately before the seg fault. I hope this is enough (but not too much) information. My idea so far is that the rebalancing is being attempting on ce after this function, but I am unsure why it would be failing. (It's unfortunately very hard for me to test this code by removing particular lines, since they would create logical inconsistencies and further problems, but if experienced programmers still think this is the way to go, I'll try.)

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  • Can I append to a preprocessor macro?

    - by JCSalomon
    Is there any way in standard C—or with GNU extensions—to append stuff to a macro definition? E.g., given a macro defined as #define quux_list X(foo) X(bar) can I append X(bas) so that it now expands as if I’d defined it #define quux_list X(foo) X(bar) X(bas)? I’m playing with discriminated/tagged unions along these lines: struct quux_foo { int x; }; struct quux_bar { char *s; }; struct quux_bas { void *p; }; enum quux_type {quux_foo, quux_bar, quux_bas}; struct quux { enum quux_type type; union { struct quux_foo foo; struct quux_bar bar; struct quux_bas bas; } t; }; I figure this is a good place for the X-macro. If I define a macro #define quux_table X(foo) X(bar) X(bas) the enumeration & structure can be defined thus, and never get out of sync: #define X(t) quux_ ## t, enum quux_type {quux_table}; #undef X #define X(t) struct quux_ ## t t; struct quux { enum quux_type type; union {quux_table} t; }; #undef X Of course, the quux_* structures can get out of sync, so I’d like to do something like this, only legally: struct quux_foo { int x; }; #define quux_table quux_table X(foo) struct quux_bar { char *s; }; #define quux_table quux_table X(bar) struct quux_bas { void *p; }; #define quux_table quux_table X(bas) (Well, what I really want to be able to do is something like member_struct(quux, foo) { int x; }; but I’m well aware that macros cannot be (re)defined from within macros.) Anyhow, that’s my motivating example. Is there a way to accomplish this? Boost.Preprocessor examples are fine, if you can show me how to make the X-macro technique work with that library.

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  • Is there any reasonable use of a function returning an anonymous struct?

    - by Akanksh
    Here is an (artificial) example of using a function that returns an anonymous struct and does "something" useful: #include <iostream> template<typename T> T* func( T* t, float a, float b ) { if(!t) { t = new T; t->a = a; t->b = b; } else { t->a += a; t->b += b; } return t; } struct { float a, b; }* foo(float a, float b) { if(a==0) return 0; return func(foo(a-1,b), a, b); } int main() { std::cout << foo(5,6)->a << std::endl; std::cout << foo(5,6)->b << std::endl; void* v = (void*)(foo(5,6)); float* f = (float*)(v); //[1] delete f now because I know struct is floats only. std::cout << f[0] << std::endl; std::cout << f[1] << std::endl; delete[] f; return 0; } There are a few points I would like to discuss: As is apparent, this code leaks, is there anyway I can NOT leak without knowing what the underlying struct definition is? see Comment [1]. I have to return a pointer to an anonymous struct so I can create an instance of the object within the templatized function func, can I do something similar without returning a pointer? I guess the most important, is there ANY (real-world) use for this at all? As the example given above leaks and is admittedly contrived. By the way, what the function foo(a,b) does is, to return a struct containing two numbers, the sum of all numbers from 1 to a and the product of a and b. EDIT: Maybe the line new T could use a boost::shared_ptr somehow to avoid leaks, but I haven't tried that. Would that work?

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  • Turn class "Interfaceable"

    - by scooterman
    Hi folks, On my company system, we use a class to represent beans. It is just a holder of information using boost::variant and some serialization/deserialization stuff. It works well, but we have a problem: it is not over an interface, and since we use modularization through dlls, building an interface for it is getting very complicated, since it is used in almost every part of our app, and sadly interfaces (abstract classes ) on c++ have to be accessed through pointers, witch makes almost impossible to refactor the entire system. Our structure is: dll A: interface definition through abstract class dll B: interface implementation there is a painless way to achieve that (maybe using templates, I don't know) or I should forget about making this work and simply link everything with dll B? thanks Edit: Here is my example. this is on dll A BeanProtocol is a holder of N dataprotocol itens, wich are acessed by a index. class DataProtocol; class UTILS_EXPORT BeanProtocol { public: virtual DataProtocol& get(const unsigned int ) const { throw std::runtime_error("Not implemented"); } virtual void getFields(std::list<unsigned int>&) const { throw std::runtime_error("Not implemented"); } virtual DataProtocol& operator[](const unsigned int ) { throw std::runtime_error("Not implemented"); } virtual DataProtocol& operator[](const unsigned int ) const { throw std::runtime_error("Not implemented"); } virtual void fromString(const std::string&) { throw std::runtime_error("Not implemented"); } virtual std::string toString() const { throw std::runtime_error("Not implemented"); } virtual void fromBinary(const std::string&) { throw std::runtime_error("Not implemented"); } virtual std::string toBinary() const { throw std::runtime_error("Not implemented"); } virtual BeanProtocol& operator=(const BeanProtocol&) { throw std::runtime_error("Not implemented"); } virtual bool operator==(const BeanProtocol&) const { throw std::runtime_error("Not implemented"); } virtual bool operator!=(const BeanProtocol&) const { throw std::runtime_error("Not implemented"); } virtual bool operator==(const char*) const { throw std::runtime_error("Not implemented"); } virtual bool hasKey(unsigned int field) const { throw std::runtime_error("Not implemented"); } }; the other class (named GenericBean) implements it. This is the only way I've found to make this work, but now I want to turn it in a truly interface and remove the UTILS_EXPORT (which is an _declspec macro), and finally remove the forced linkage of B with A.

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  • Help with infrequent segmentation fault in accessing struct

    - by Sarah
    I'm having trouble debugging a segmentation fault. I'd appreciate tips on how to go about narrowing in on the problem. The error appears when an iterator tries to access an element of a struct Infection, defined as: struct Infection { public: explicit Infection( double it, double rt ) : infT( it ), recT( rt ) {} double infT; // infection start time double recT; // scheduled recovery time }; These structs are kept in a special structure, InfectionMap: typedef boost::unordered_multimap< int, Infection > InfectionMap; Every member of class Host has an InfectionMap carriage. Recovery times and associated host identifiers are kept in a priority queue. When a scheduled recovery event arises in the simulation for a particular strain s in a particular host, the program searches through carriage of that host to find the Infection whose recT matches the recovery time (double recoverTime). (For reasons that aren't worth going into, it's not as expedient for me to use recT as the key to InfectionMap; the strain s is more useful, and coinfections with the same strain are possible.) assert( carriage.size() > 0 ); pair<InfectionMap::iterator,InfectionMap::iterator> ret = carriage.equal_range( s ); InfectionMap::iterator it; for ( it = ret.first; it != ret.second; it++ ) { if ( ((*it).second).recT == recoverTime ) { // produces seg fault carriage.erase( it ); } } I get a "Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address..." on the line specified above. The recoverTime is fine, and the assert(...) in the code is not tripped. As I said, this seg fault appears 'randomly' after thousands of successful recovery events. How would you go about figuring out what's going on? I'd love ideas about what could be wrong and how I can further investigate the problem.

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  • Function-Local Static Const variable Initialization semantics.

    - by Hassan Syed
    The questions are in bold, for those that cannot be bothered reading a question in depth. This is a followup to this question. It is to do with the initialization semantics of static variables in functions. Static variables should be initialized once, and their internal state might be altered later - as I (currently) do in the linked question. However, the code in question does not require the feature to change the state of the variable later. Let me clarrify my position, since I don't require the string object's internal state to change. The code is for a trait class for meta programming, and as such would would benifit from a const char * const ptr -- thus Ideally a local cost static const variable is needed. My educated guess is that in this case the string in question will be optimally placed in memory by the link-loader, and that the code is more secure and maps to the intended semantics. This leads to the semantics of such a variable "The C++ Programming language Third Edition -- Stroustrup" does not have anything (that I could find) to say about this matter. All that is said is that the variable is initialized once when the flow of control of the thread first reaches the code. This leads me to ponder if the following code would be sensible, and if not what are the intended semantics ?. #include <iostream> const char * const GetString(const char * x_in) { static const char * const x = x_in; return x; } int main() { const char * const temp = GetString("yahoo"); std::cout << temp << std::endl; const char * const temp2 = GetString("yahoo2"); std::cout << temp2 << std::endl; } The following compiles on GCC and prints "yahoo" twice. Which is what I want -- However it might not be standards compliant (which is why I post this question). It might be more elegant to have two functions, "SetString" and "String" where the latter forwards to the first. If it is standards compliant does someone know of a templates implementation in boost (or elsewhere) ?

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  • Can GPU capabilities impact virtual machine performance?

    - by Dave White
    While this many not seem like a programming question directly, it impacts my development activities and so it seems like it belongs here. It seems that more and more developers are turning to virtual environments for development activities on their computers, SharePoint development being a prime example. Also, as a trainer, I have virtual training environments for all of the classes that I teach. I recently purchased a new Dell E6510 to travel around with. It has the i7 620M (Dual core, HyperThreaded cpu running at 2.66GHz) and 8 GB of memory. Reading the spec sheet, it sounded like it would be a great laptop to carry around and run virtual machines on. Getting the laptop though, I've been pretty disappointed with the user experience of developing in a virtual machine. Giving the Virtual Machine 4 GB of memory, it was slow and I could type complete sentences and watch the VM "catchup". My company has training laptops that we provide for our classes. They are Dell Precision M6400 Intel Core 2 Duo P8700 running at 2.54Ghz with 8 GB of memory and the experience on this laptops is night and day compared to the E6510. They are crisp and you barely aware that you are running in a virtual environment. Since the E6510 should be faster in all categories than the M6400, I couldn't understand why the new laptop was slower, so I did a component by component comparison and the only place where the E6510 is less performant than the M6400 is the graphics department. The M6400 is running a nVidia FX 2700m GPU and the E6510 is running a nVidia 3100M GPU. Looking at benchmarks of the two GPUs suggest that the FX 2700M is twice as fast as the 3100M. http://www.notebookcheck.net/Mobile-Graphics-Cards-Benchmark-List.844.0.html 3100M = 111th (E6510) FX 2700m = 47th (Precision M6400) Radeon HD 5870 = 8th (Alienware) The host OS is Windows 7 64bit as is the guest OS, running in Virtual Box 3.1.8 with Guest Additions installed on the guest. The IDE being used in the virtual environment is VS 2010 Premium. So after that long setup, my question is: Is the GPU significantly impacting the virtual machine's performance or are there other factors that I'm not looking at that I can use to boost the vm's performance? Do we now have to consider GPU performance when purchasing laptops where we expect to use virtualized development environments? Thanks in advance. Cheers, Dave

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  • How to learn proper C++?

    - by Chris
    While reading a long series of really, really interesting threads, I've come to a realization: I don't think I really know C++. I know C, I know classes, I know inheritance, I know templates (& the STL) and I know exceptions. Not C++. To clarify, I've been writing "C++" for more than 5 years now. I know C, and I know that C and C++ share a common subset. What I've begun to realize, though, is that more times than not, I wind up treating C++ something vaguely like "C with classes," although I do practice RAII. I've never used Boost, and have only read up on TR1 and C++0x - I haven't used any of these features in practice. I don't use namespaces. I see a list of #defines, and I think - "Gracious, that's horrible! Very un-C++-like," only to go and mindlessly write class wrappers for the sake of it, and I wind up with large numbers (maybe a few per class) of static methods, and for some reason, that just doesn't seem right lately. The professional in me yells "just get the job done," the academic yells "you should write proper C++ when writing C++" and I feel like the point of balance is somewhere in between. I'd like to note that I don't want to program "pure" C++ just for the sake of it. I know several languages. I have a good feel for what "Pythonic" is. I know what clean and clear PHP is. Good C code I can read and write better than English. The issue is that I learned C by example, and picked up C++ as a "series of modifications" to C. And a lot of my early C++ work was creating class wrappers for C libraries. I feel like my own personal C-heavy background while learning C++ has sort of... clouded my acceptance of C++ in it's own right, as it's own language. Do the weathered C++ lags here have any advice for me? Good examples of clean, sharp C++ to learn from? What habits of C does my inner-C++ really need to break from? My goal here is not to go forth and trumpet "good" C++ paradigm from rooftops for the sake of it. C and C++ are two different languages, and I want to start treating them that way. How? Where to start? Thanks in advance! Cheers, -Chris

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  • Is it ok to dynamic cast "this" as a return value?

    - by Panayiotis Karabassis
    This is more of a design question. I have a template class, and I want to add extra methods to it depending on the template type. To practice the DRY principle, I have come up with this pattern (definitions intentionally omitted): template <class T> class BaseVector: public boost::array<T, 3> { protected: BaseVector<T>(const T x, const T y, const T z); public: bool operator == (const Vector<T> &other) const; Vector<T> operator + (const Vector<T> &other) const; Vector<T> operator - (const Vector<T> &other) const; Vector<T> &operator += (const Vector<T> &other) { (*this)[0] += other[0]; (*this)[1] += other[1]; (*this)[2] += other[2]; return *dynamic_cast<Vector<T> * const>(this); } } template <class T> class Vector : public BaseVector<T> { public: Vector<T>(const T x, const T y, const T z) : BaseVector<T>(x, y, z) { } }; template <> class Vector<double> : public BaseVector<double> { public: Vector<double>(const double x, const double y, const double z); Vector<double>(const Vector<int> &other); double norm() const; }; I intend BaseVector to be nothing more than an implementation detail. This works, but I am concerned about operator+=. My question is: is the dynamic cast of the this pointer a code smell? Is there a better way to achieve what I am trying to do (avoid code duplication, and unnecessary casts in the user code)? Or am I safe since, the BaseVector constructor is private?

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  • Multi-threaded Pooled Allocators

    - by Darren Engwirda
    I'm having some issues using pooled memory allocators for std::list objects in a multi-threaded application. The part of the code I'm concerned with runs each thread function in isolation (i.e. there is no communication or synchronization between threads) and therefore I'd like to setup separate memory pools for each thread, where each pool is not thread-safe (and hence fast). I've tried using a shared thread-safe singleton memory pool and found the performance to be poor, as expected. This is a heavily simplified version of the type of thing I'm trying to do. A lot has been included in a pseudo-code kind of way, sorry if it's confusing. /* The thread functor - one instance of MAKE_QUADTREE created for each thread */ class make_quadtree { private: /* A non-thread-safe memory pool for int linked list items, let's say that it's * something along the lines of BOOST::OBJECT_POOL */ pooled_allocator<int> item_pool; /* The problem! - a local class that would be constructed within each std::list as the * allocator but really just delegates to ITEM_POOL */ class local_alloc { public : //!! I understand that I can't access ITEM_POOL from within a nested class like //!! this, that's really my question - can I get something along these lines to //!! work?? pointer allocate (size_t n) { return ( item_pool.allocate(n) ); } }; public : make_quadtree (): item_pool() // only construct 1 instance of ITEM_POOL per // MAKE_QUADTREE object { /* The kind of data structures - vectors of linked lists * The idea is that all of the linked lists should share a local pooled allocator */ std::vector<std::list<int, local_alloc>> lists; /* The actual operations - too complicated to show, but in general: * * - The vector LISTS is grown as a quadtree is built, it's size is the number of * quadtree "boxes" * * - Each element of LISTS (each linked list) represents the ID's of items * contained within each quadtree box (say they're xy points), as the quadtree * is grown a lot of ID pop/push-ing between lists occurs, hence the memory pool * is important for performance */ } }; So really my problem is that I'd like to have one memory pool instance per thread functor instance, but within each thread functor share the pool between multiple std::list objects.

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  • Internet Explorer 8 + Deflate

    - by Andreas Bonini
    I have a very weird problem.. I really do hope someone has an answer because I wouldn't know where else to ask. I am writing a cgi application in C++ which is executed by Apache and outputs HTML code. I am compressing the HTML output myself - from within my C++ application - since my web host doesn't support mod_deflate for some reason. I tested this with Firefox 2, Firefox 3, Opera 9, Opera 10, Google Chrome, Safari, IE6, IE7, IE8, even wget.. It works with ANYTHING except IE8. IE8 just says "Internet Explorer cannot display the webpage", with no information whatsoever. I know it's because of the compression only because it works if I disable it. Do you know what I'm doing wrong? I use zlib to compress it, and the exact code is: /* Compress it */ int compressed_output_size = content.length() + (content.length() * 0.2) + 16; char *compressed_output = (char *)Alloc(compressed_output_size); int compressed_output_length; Compress(compressed_output, compressed_output_size, (void *)content.c_str(), content.length(), &compressed_output_length); /* Send the compressed header */ cout << "Content-Encoding: deflate\r\n"; cout << boost::format("Content-Length: %d\r\n") % compressed_output_length; cgiHeaderContentType("text/html"); cout.write(compressed_output, compressed_output_length); static void Compress(void *to, size_t to_size, void *from, size_t from_size, int *final_size) { int ret; z_stream stream; stream.zalloc = Z_NULL; stream.zfree = Z_NULL; stream.opaque = Z_NULL; if ((ret = deflateInit(&stream, CompressionSpeed)) != Z_OK) COMPRESSION_ERROR("deflateInit() failed: %d", ret); stream.next_out = (Bytef *)to; stream.avail_out = (uInt)to_size; stream.next_in = (Bytef *)from; stream.avail_in = (uInt)from_size; if ((ret = deflate(&stream, Z_NO_FLUSH)) != Z_OK) COMPRESSION_ERROR("deflate() failed: %d", ret); if (stream.avail_in != 0) COMPRESSION_ERROR("stream.avail_in is not 0 (it's %d)", stream.avail_in); if ((ret = deflate(&stream, Z_FINISH)) != Z_STREAM_END) COMPRESSION_ERROR("deflate() failed: %d", ret); if ((ret = deflateEnd(&stream)) != Z_OK) COMPRESSION_ERROR("deflateEnd() failed: %d", ret); if (final_size) *final_size = stream.total_out; return; }

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  • Remove never-run call to templated function, get allocation error on run-time

    - by Narfanator
    First off, I'm a bit at a loss as to how to ask this question. So I'm going to try throwing lots of information at the problem. Ok, so, I went to completely redesign my test project for my experimental core library thingy. I use a lot of template shenanigans in the library. When I removed the "user" code, the tests gave me a memory allocation error. After quite a bit of experimenting, I narrowed it down to this bit of code (out of a couple hundred lines): void VOODOO(components::switchBoard &board){ board.addComponent<using_allegro::keyInputs<'w'> >(); } Fundementally, what's weirding me out is that it appears that the act of compiling this function (and the template function it then uses, and the template functions those then use...), makes this bug not appear. This code is not being run. Similar code (the same, but for different key vals) occurs elsewhere, but is within Boost TDD code. I realize I certainly haven't given enough information for you to solve it for me; I tried, but it more-or-less spirals into most of the code base. I think I'm most looking for "here's what the problem could be", "here's where to look", etc. There's something that's happening during compile because of this line, but I don't know enough about that step to begin looking. Sooo, how can a (presumably) compilied, but never actually run, bit of templated code, when removed, cause another part of code to fail? Error: Unhandled exceptionat 0x6fe731ea (msvcr90d.dll) in Switchboard.exe: 0xC0000005: Access violation reading location 0xcdcdcdc1. Callstack: operator delete(void * pUser Data) allocator< class name related to key inputs callbacks ::deallocate vector< same class ::_Insert_n(...) vector< " " ::insert(...) vector<" "::push_back(...) It looks like maybe the vector isn't valid, because _MyFirst and similar data members are showing values of 0xcdcdcdcd in the debugger. But the vector is a member variable...

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  • initializing a vector of custom class in c++

    - by Flamewires
    Hey basically Im trying to store a "solution" and create a vector of these. The problem I'm having is with initialization. Heres my class for reference class Solution { private: // boost::thread m_Thread; int itt_found; int dim; pfn_fitness f; double value; std::vector<double> x; public: Solution(size_t size, int funcNo) : itt_found(0), x(size, 0.0), value(0.0), dim(30), f(Eval_Functions[funcNo]) { for (int i = 1; i < (int) size; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[funcNo]; } } Solution() : itt_found(0), x(31, 0.0), value(0.0), dim(30), f(Eval_Functions[1]) { for (int i = 1; i < 31; i++) { x[i] = ((double)rand()/((double)RAND_MAX))*maxs[1]; } } Solution operator= (Solution S) { x = S.GetX(); itt_found = S.GetIttFound(); dim = S.GetDim(); f = S.GetFunc(); value = S.GetValue(); return *this; } void start() { value = f (dim, x); } /* plus additional getter/setter methods*/ } Solution S(30, 1) or Solution(2, 5) work and initalizes everything, but I need X of these solution objects. std::vector<Solution> Parents(X) will create X solutions with the default constructor and i want to construct using the (int, int) constructor. Is there any easy(one liner?) way to do this? Or would i have to do something like: size_t numparents = 10; vector<Solution> Parents; Parents.reserve(numparents); for (int i = 0; i<(int)numparents; i++) { Solution S(31, 0); Parents.push_back(S); }

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  • stxxl Assertion `it != root_node_.end()' failed

    - by Fabrizio Silvestri
    I am receiving this assertion failed error when trying to insert an element in a stxxl map. The entire assertion error is the following: resCache: /usr/include/stxxl/bits/containers/btree/btree.h:470: std::pair , bool stxxl::btree::btree::insert(const value_type&) [with KeyType = e_my_key, DataType = unsigned int, CompareType = comp_type, unsigned int RawNodeSize = 16384u, unsigned int RawLeafSize = 131072u, PDAllocStrategy = stxxl::SR, stxxl::btree::btree::value_type = std::pair]: Assertion `it != root_node_.end()' failed. Aborted Any idea? Edit: Here's the code fragment void request_handler::handle_request(my_key& query, reply& rep) { c_++; strip(query.content); std::cout << "Received query " << query.content << " by thread " << boost::this_thread::get_id() << ". It is number " << c_ << "\n"; strcpy(element.first.content, query.content); element.second = c_; testcache_.insert(element); STXXL_MSG("Records in map: " << testcache_.size()); } Edit2 here's more details (I omit constants, e.g. MAX_QUERY_LEN) struct comp_type : std::binary_function<my_key, my_key, bool> { bool operator () (const my_key & a, const my_key & b) const { return strncmp(a.content, b.content, MAX_QUERY_LEN) < 0; } static my_key max_value() { return max_key; } static my_key min_value() { return min_key; } }; typedef stxxl::map<my_key, my_data, comp_type> cacheType; cacheType testcache_; request_handler::request_handler() :testcache_(NODE_CACHE_SIZE, LEAF_CACHE_SIZE) { c_ = 0; memset(max_key.content, (std::numeric_limits<unsigned char>::max)(), MAX_QUERY_LEN); memset(min_key.content, (std::numeric_limits<unsigned char>::min)(), MAX_QUERY_LEN); testcache_.enable_prefetching(); STXXL_MSG("Records in map: " << testcache_.size()); }

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