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• Embedded non-relational (nosql) data store

  - by Igor Brejc

  I'm thinking about using/implementing some kind of an embedded key-value (or document) store for my Windows desktop application. I want to be able to store various types of data (GPS tracks would be one example) and of course be able to query this data. The amount of data would be such that it couldn't all be loaded into memory at the same time. I'm thinking about using sqlite as a storage engine for a key-value store, something like y-serial, but written in .NET. I've also read about FriendFeed's usage of MySQL to store schema-less data, which is a good pointer on how to use RDBMS for non-relational data. sqlite seems to be a good option because of its simplicity, portability and library size. My question is whether there are any other options for an embedded non-relational store? It doesn't need to be distributable and it doesn't have to support transactions, but it does have to be accessible from .NET and it should have a small download size. UPDATE: I've found an article titled SQLite as a Key-Value Database which compares sqlite with Berkeley DB, which is an embedded key-value store library.

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• Android ANR keyDispatchingTimedOut Error while continuous tapping on screen.

  - by user519846

  Hi All, I am getting Application Not Responding (ANR) dialog while continuous tapping on the screen. There is no view on the screen where i am tapping. Frequency of this issue is less but still i am not able to remove it completely. Here i am attaching the log what i caught during this error. ERROR/ActivityManager(1322): ANR in com.test.mj.and.ui (com.test.mj.and.ui/.TermsAndCondActivity) ERROR/ActivityManager(1322): Reason: keyDispatchingTimedOut ERROR/ActivityManager(1322): Parent: com.test.mj.and.ui/.SplashActivity ERROR/ActivityManager(1322): Load: 6.59 / 6.37 / 5.21 ERROR/ActivityManager(1322): CPU usage from 11430ms to 2196ms ago: ERROR/ActivityManager(1322): rtal.mj.and.ui: 9% = 7% user + 1% kernel / faults: 649 minor ERROR/ActivityManager(1322): system_server: 4% = 2% user + 2% kernel / faults: 10 minor ERROR/ActivityManager(1322): logcat: 3% = 1% user + 1% kernel / faults: 675 minor 1 major ERROR/ActivityManager(1322): synaptics_wq: 1% = 0% user + 1% kernel ERROR/ActivityManager(1322): ami304d: 1% = 0% user + 0% kernel ERROR/ActivityManager(1322): .process.lghome: 1% = 0% user + 0% kernel / faults: 47 minor ERROR/ActivityManager(1322): sync_supers: 0% = 0% user + 0% kernel ERROR/ActivityManager(1322): droid.DunServer: 0% = 0% user + 0% kernel / faults: 6 minor ERROR/ActivityManager(1322): events/0: 0% = 0% user + 0% kernel ERROR/ActivityManager(1322): oid.inputmethod: 0% = 0% user + 0% kernel / faults: 2 minor ERROR/ActivityManager(1322): m.android.phone: 0% = 0% user + 0% kernel / faults: 2 minor ERROR/ActivityManager(1322): ndroid.settings: 0% = 0% user + 0% kernel ERROR/ActivityManager(1322): sh: 0% = 0% user + 0% kernel / faults: 110 minor ERROR/ActivityManager(1322): -flush-179:0: 0% = 0% user + 0% kernel ERROR/ActivityManager(1322): TOTAL: 19% = 13% user + 6% kernel WARN/WindowManager(1322): Continuing to wait for key to be dispatched WARN/WindowManager(1322): No window to dispatch pointer action 1 Can anyone please help me to solve this issue? Thanks in advance.

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• Moq, a translator and an expression

  - by jeriley

  I'm working with an expression within a moq-ed "Get Service" and ran into a rather annoying issue. In order to get this test to run correctly and the get service to return what it should, there's a translator in between that takes what you've asked for, sends it off and gets what you -really- want. So, thinking this was easy I attempt this ... the fakelist is the TEntity objects (translated, used by the UI) and TEnterpriseObject is the actual persistance. mockGet.Setup(mock => mock.Get(It.IsAny<Expression<Func<TEnterpriseObject, bool>>>())).Returns( (Expression<Func<TEnterpriseObject, bool>> expression) => { var items = new List<TEnterpriseObject>(); var translator = (IEntityTranslator<TEntity, TEnterpriseObject>) ObjectFactory.GetInstance(typeof (IEntityTranslator<TEntity, TEnterpriseObject>)); fakeList.ForEach(fake => items.Add(translator.ToEnterpriseObject(fake))); items = items.Where(expression); var result = new List<TEnterpriseObject>(items); fakeList.Clear(); result.ForEach(item => translator.ToEntity(item)); return items; }); I'm getting the red squigglie under there items.where(expression) -- says it can't be infered from usage (confused between <Func<TEnterpriseObject,bool>> and <Func<TEnterpriseObject,int,bool>>) A far simpler version works great ... mockGet.Setup(mock => mock.Get(It.IsAny<Expression<Func<TEntity, bool>>>())).Returns( (Expression<Func<TEntity, bool>> expression) => fakeList.AsQueryable().Where(expression)); so I'm not sure what I'm missing... ideas?

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• Why do I get CA1806 when I catch exception in C++/CLI?

  - by brickner

  I've recently upgraded my project from Visual Studio 2008 to Visual Studio 2010. By enabling Code Analysis and compiling in Release, I'm getting warning CA1806: Do not ignore method results. I've managed to reduce the code that produces the warning to this code: .h file: public ref class Foo { public: void Bar(); }; .cpp file: void Foo::Bar() { try { } catch (const std::exception&) // here I get the warning { } } the warning: CA1806 : Microsoft.Usage : 'Foo::Bar(void)' calls 'Global::__CxxRegisterExceptionObject(void*, void*)' but does not use the HRESULT or error code that the method returns. This could lead to unexpected behavior in error conditions or low-resource situations. Use the result in a conditional statement, assign the result to a variable, or pass it as an argument to another method. If I try to use the exception value or do catch(...) the warning still appears. If I catch managed exceptions instead or compile in Debug I don't get the warning. Why do I get this warning? UPDATE I've decided to open a bug report on Microsoft Connect.

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• Reasons for & against a Database

  - by dbemerlin

  Hi, i had a discussion with a coworker about the architecture of a program i'm writing and i'd like some more opinions. The Situation: The Program should update at near-realtime (+/- 1 Minute). It involves the movement of objects on a coordinate system. There are some events that occur at regular intervals (i.e. creation of the objects). Movements can change at any time through user input. My solution was: Build a server that runs continously and stores the data internally. The server dumps a state-of-the-program at regular intervals to protect against powerfailures and/or crashes. He argued that the program requires a Database and i should use cronjobs to update the data. I can store movement information by storing startpoint, endpoint and speed and update the position in the cronjob (and calculate collisions with other objects there) by calculating direction and speed. His reasons: Requires more CPU & Memory because it runs constantly. Powerfailures/Crashes might destroy data. Databases are faster. My reasons against this are mostly: Not very precise as events can only occur at full minutes (wouldn't be that bad though). Requires (possibly costly) transformation of data on every run from relational data to objects. RDBMS are a general solution for a specialized problem so a specialized solution should be more efficient. Powerfailures (or other crashes) can leave the Data in an undefined state with only partially updated data unless (possibly costly) precautions (like transactions) are taken. What are your opinions about that? Which arguments can you add for any side?

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• Bugzilla Install question - I'm stuck

  - by Nabeel

  I run Bugzilla's checksetup.pl (migrating an older version), and it always returns: Reading ./localconfig... Checking for DBD-mysql (v4.00) ok: found v4.005 Had to create DBD::mysql::dr::imp_data_size unexpectedly at /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi/DBI.pm line 1229, <DATA> line 225. Use of uninitialized value in subroutine entry at /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi/DBI.pm line 1229, <DATA> line 225. Had to create DBD::mysql::db::imp_data_size unexpectedly at /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi/DBI.pm line 1259, <DATA> line 225. Use of uninitialized value in subroutine entry at /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi/DBI.pm line 1259, <DATA> line 225. There was an error connecting to MySQL: Undefined subroutine &DBD::mysql::db::_login called at /usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi/DBD/mysql.pm line 142, <DATA> line 225. MySQL Version: [root@bugzilla-core TMP]# mysql --version mysql Ver 14.12 Distrib 5.0.60sp1, for redhat-linux-gnu (x86_64) using readline 5.1 And mysql_config: [root@bugzilla-core TMP]# mysql_config Usage: /data01/mysql-5.0.60/bin/mysql_config [OPTIONS] Options: --cflags [-I/data01/mysql-5.0.60/include -g] --include [-I/data01/mysql-5.0.60/include] --libs [-rdynamic -L/data01/mysql-5.0.60/lib -lmysqlclient -lz -lcrypt -lnsl -lm -lmygcc] --libs_r [-rdynamic -L/data01/mysql-5.0.60/lib -lmysqlclient_r -lz -lpthread -lcrypt -lnsl -lm -lpthread -lmygcc] --socket [/tmp/mysql.sock] --port [0] --version [5.0.60sp1] --libmysqld-libs [-rdynamic -L/data01/mysql-5.0.60/lib -lmysqld -lz -lpthread -lcrypt -lnsl -lm -lpthread -lrt -lmygcc] Now, I've tried the latest version of DBD-mysql (4.0.14). I'm completely lost and stumped. I'm not sure where to go from here. Scouring the 'webs haven't returned anything fruitful. Any ideas?

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• How to allow users to define financial formulas in a C# app

  - by Peter Morris

  I need to allow my users to be able to define formulas which will calculate values based on data. For example //Example 1 return GetMonetaryAmountFromDatabase("Amount due") * 1.2; //Example 2 return GetMonetaryAmountFromDatabase("Amount due") * GetFactorFromDatabase("Discount"); I will need to allow / * + - operations, also to assign local variables and execute IF statements, like so var amountDue = GetMonetaryAmountFromDatabase("Amount due"); if (amountDue > 100000) return amountDue * 0.75; if (amountDue > 50000) return amountDue * 0.9; return amountDue; The scenario is complicated because I have the following structure.. Customer (a few hundred) Configuration (about 10 per customer) Item (about 10,000 per customer configuration) So I will perform a 3 level loop. At each "Configuration" level I will start a DB transaction and compile the forumlas, each "Item" will use the same transaction + compiled formulas (there are about 20 formulas per configuration, each item will use all of them). This further complicates things because I can't just use the compiler services as it would result in continued memory usage growth. I can't use a new AppDomain per each "Configuration" loop level because some of the references I need to pass cannot be marshalled. Any suggestions?

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• How much of STL is too much?

  - by Darius Kucinskas

  I am using a lot of STL code with std::for_each, bind, and so on, but I noticed that sometimes STL usage is not good idea. For example if you have a std::vector and want to do one action on each item of the vector, your first idea is to use this: std::for_each(vec.begin(), vec.end(), Foo()) and it is elegant and ok, for a while. But then comes the first set of bug reports and you have to modify code. Now you should add parameter to call Foo(), so now it becomes: std::for_each(vec.begin(), vec.end(), std::bind2nd(Foo(), X)) but that is only temporary solution. Now the project is maturing and you understand business logic much better and you want to add new modifications to code. It is at this point that you realize that you should use old good: for(std::vector::iterator it = vec.begin(); it != vec.end(); ++it) Is this happening only to me? Do you recognise this kind of pattern in your code? Have you experience similar anti-patterns using STL?

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• Run a PHP script every second using CLI

  - by Saif Bechan

  Hello, I have a dedicated server running Cent OS with a Parallel PLESK panel. I need to run a php script every second, that updates my database. These is no alternative way timewise, i have checked every method, it needs to be updated every second. I can find my script using the url: http://www.mysite.com/phpfile.php?key=123, and this has to be executed every second. Does anyone have any knowledge at all on doing this, i can not seem to find the answer. I heard about doing it with CLI and putty, but i have no knowledge of this at all. Or can this be done using the PLESK Panel? And can the file be executed locally every second. Like \phpfile.php If someone helps me on answering these question i would really appreciate it. Regards EDIT It has been a few months since i added this question. I ended up using the following code: #!/user/bin/php $start = microtime(true); set_time_limit(60); for (i = 0; i < 59; ++$i) { doMyThings(); time_sleep_until($start + $i + 1); } Thank you for this code guys! My cronjob is set to every minute. I have been running this for some time now in a test environment, and this works out great. It works really supperfast, and i see no increase in CPU nor Memory usage.

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• MSTest on x64 C++/CLI

  - by Oyvind

  I got a problem using MSTest on x64: The test project depends on a couple of C++/CLI assemblies, and fails to load for some reason. In Visual Studio, I get (stripped down): Error loading D:\xxx\Xxx.Test.dll: Unable to load the test container 'D:\xxx\Xxx.Test.dll' or one of its dependencies. Error details: System.BadImageFormatException: Could not load file or assembly 'Common.Geometry.Native, Version=1.1.4574.22395, Culture=neutral, PublicKeyToken=null' or one of its dependencies. An attempt was made to load a program with an incorrect format. Running MSTest manually in a command prompt, I get: Unable to load the test container 'D:\xxx\Xxx.Test.dll' or one of its dependencies. Error details: System.IO.FileNotFoundException: Could not load file or assembly 'Common.Geometry.Native, Version=1.1.4574.22395, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified. Details worth mentioning: The test project itself is compiled using 'Any Cpu'. I use a x64 specific testrunconfig Dependency walker shows no missing native dependencies in the C++/CLI assembly (Common.Geometry.Native) Even more interesting, there is another test project in the same solution using the same C++/CLI assembly (Common.Geometry.Native), and it runs without any problems. I have also verified that there are no 32bit assemblies/dlls interfering. Any suggestions is welcome !

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• What header file is where the boost libray define its own primitive data type?

  - by ronghai

  Recently, I try to use the boost::spirit::qi binary endian parser to parse some binary data depends on the endianness of the Platform. There is a simple example, like following: Using declarations and variables: using boost::spirit::qi::little_word; using boost::spirit::qi::little_dword; using boost::spirit::qi::little_qword; boost::uint16_t us; boost::uint32_t ui; boost::uint64_t ul; Basic usage of the little endian binary parsers: test_parser_attr("\x01\x02", little_word, us); assert(us == 0x0201); test_parser_attr("\x01\x02\x03\x04", little_dword, ui); assert(ui == 0x04030201); test_parser_attr("\x01\x02\x03\x04\x05\x06\x07\x08", little_qword, ul); assert(ul == 0x0807060504030201LL); test_parser("\x01\x02", little_word(0x0201)); test_parser("\x01\x02\x03\x04", little_dword(0x04030201)); test_parser("\x01\x02\x03\x04\x05\x06\x07\x08", little_qword(0x0807060504030201LL)); It works very well. But my questions come, why do we need use some data types like boost::uint16_t, boost::uint32_t here? Can I use unsigned long or unsigned int here? And if I want to parse double or float data type, what boost data type should I use? And please tell me where is boost define the above these types? Thanks a lot.

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• mprotect - how aligning to multiple of pagesize works?

  - by user299988

  Hi, I am not understanding the 'aligning allocated memory' part from the mprotect usage. I am referring to the code example given on http://linux.die.net/man/2/mprotect char *p; char c; /* Allocate a buffer; it will have the default protection of PROT_READ|PROT_WRITE. */ p = malloc(1024+PAGESIZE-1); if (!p) { perror("Couldn't malloc(1024)"); exit(errno); } /* Align to a multiple of PAGESIZE, assumed to be a power of two */ p = (char *)(((int) p + PAGESIZE-1) & ~(PAGESIZE-1)); c = p[666]; /* Read; ok */ p[666] = 42; /* Write; ok */ /* Mark the buffer read-only. */ if (mprotect(p, 1024, PROT_READ)) { perror("Couldn't mprotect"); exit(errno); } For my understanding, I tried using a PAGESIZE of 16, and 0010 as address of p. I ended up getting 0001 as the result of (((int) p + PAGESIZE-1) & ~(PAGESIZE-1)). Could you please clarify how this whole 'alignment' works? Thanks,

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• Upload An Excel File in Classic ASP On Windows 2003 x64 Using Office 2010 Drivers

  - by alphadogg

  So, we are migrating an old web app from a 32-bit server to a newer 64-bit server. The app is basically a Classic ASP app. The pool is set to run in 64-bit and cannot be set to 32-bit due to other components. However, this breaks the old usage of Jet drivers and subsequent parsing of Excel files. After some research, I downloaded the 64-bit version of the new 2010 Office System Driver Beta and installed it. Presumably, this allows one to open and read Excel and CSV files. Here's the snippet of code that errors out. Think I followed the lean guidelines on the download page: Set con = Server.CreateObject("ADODB.Connection") con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.14.0;Data Source=" & strPath & ";Extended Properties=""Excel 14.0;""" con.Open Any ideas why? UPDATE: My apologies. I did forget the important part, the error message: ADODB.Connection error '800a0e7a' Provider cannot be found. It may not be properly installed. /vendor/importZipList2.asp, line 56 I have installed, and uninstalled/reinstalled twice.

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• What is the best way to iterate over a large result set in JDBC/iBatis 3?

  - by paul_sns

  We're trying to iterate over a large number of rows from the database and convert those into objects. Behavior will be as follows: Result will be sorted by sequence id, a new object will be created when sequence id changes. The object created will be sent to an external service and will sometimes have to wait before sending another one (which means the next set of data will not be immediately used) We already have invested code in iBatis 3 so an iBatis solution will be the best approach for us (we've tried using RowBounds but haven't seen how it does the iteration under the hood). We'd like to balance minimizing memory usage and reducing number of DB trips. We're also open to pure JDBC approach but we'd like the solution to work on different databases. UPDATE: We need to make as few calls to DB as possible (1 call would be the ideal scenario) while also preventing the application to use too much memory. Are there any other solutions out there for this type of problem may it be pure JDBC or any other technology? Thanks and hope to hear your insights on this.

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• Perl Parallel::ForkManager wait_all_children() takes excessively long time

  - by zhang18

  I have a script that uses Parallel::ForkManager. However, the wait_all_children() process takes incredibly long time even after all child-processes are completed. The way I know is by printing out some timestamps (see below). Does anyone have any idea what might be causing this (I have 16 CPU cores on my machine)? my $pm = Parallel::ForkManager->new(16) for my $i (1..16) { $pm->start($i) and next; ... do something within the child-process ... print (scalar localtime), " Process $i completed.\n"; $pm->finish(); } print (scalar localtime), " Waiting for some child process to finish.\n"; $pm->wait_all_children(); print (scalar localtime), " All processes finished.\n"; Clearly, I'll get the Waiting for some child process to finish message first, with a timestamp of, say, 7:08:35. Then I'll get a list of Process i completed messages, with the last one at 7:10:30. However, I do not receive the message All Processes finished until 7:16:33(!). Why is that 6-minute delay between 7:10:30 and 7:16:33? Thx!

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• Fast, very lightweight algorithm for camera motion detection?

  - by Ertebolle

  I'm working on an augmented reality app for iPhone that involves a very processor-intensive object recognition algorithm (pushing the CPU at 100% it can get through maybe 5 frames per second), and in an effort to both save battery power and make the whole thing less "jittery" I'm trying to come up with a way to only run that object recognizer when the user is actually moving the camera around. My first thought was to simply use the iPhone's accelerometers / gyroscope, but in testing I found that very often people would move the iPhone at a consistent enough attitude and velocity that there wouldn't be any way to tell that it was still in motion. So that left the option of analyzing the actual video feed and detecting movement in that. I got OpenCV working and tried running their pyramidal Lucas-Kanade optical flow algorithm, which works well but seems to be almost as processor-intensive as my object recognizer - I can get it to an acceptable framerate if I lower the depth levels / downsample the image / track fewer points, but then accuracy suffers and it starts to miss some large movements and trigger on small hand-shaking-y ones. So my question is, is there another optical flow algorithm that's faster than Lucas-Kanade if I just want to detect the overall magnitude of camera movement? I don't need to track individual objects, I don't even need to know which direction the camera is moving, all I really need is a way to feed something two frames of video and have it tell me how far apart they are.

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• Improve Application Performace

  - by Gtest

  Hello, Want To Improvide Performace Of C#.Net Applicaiton.. In My Application I am using Third Party Interop/Dll To Process .doc Files. It's a Simple Operation, Which Pass Input/Output FilePath to Interop dll ...& dll will execute text form input file. To Improve Performace I have Tried, Execute 2 therad to process 32 files.(each Thread process 16 files) Execute application code by creating 2 new AppDomains(each AppDomain Code process 16 files) Execute Code Using TPL(Task Parellel Library) But all options take around same time (32 sec) to process 32 files.Manually process tooks same 32 sec to process 32 files. Just tried one thing ..when i have created sample exe to process 16 files as input & output for refrence PAth given in TextBox. ..I open 2 exe instance to process. 1 exe has differnt 16 input files & output Created with input file path 2 exe has differnt 16 input files & output Created with input file path When i click on start button of both exe ..it use 100% cpu & Utilize both core significantly & Process Completed within 16 sec for 32 files. Can we provide this kind of explicit prallism to Improve my applicaiton Peformace? Thanks.

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• structure inside structure - c++ Error

  - by gamadeus

  First of all the error I am getting is of the type: Request for member 's' of struct1.struct1::struct2, which is of non class type '__u32' where: struct struct1 { struct x struct2; struct x struct3; struct x struct4; }; The usage is of the form: struct struct1 st1; st1.struct2.s = Value; Now my struct1 is: struct ip_mreq_source { struct in_addr imr_multiaddr; struct in_addr imr_sourceaddr; struct in_addr imr_interface; }; struct 'x' is in_addr Where: typedef uint32_t in_addr_t; struct in_addr { in_addr_t s_addr; }; element 's' is the element s_addr in in_addr. My detailed error coming out of g++ (GCC 4.4.3) from the Android based compiler: arm-linux-androideabi-g++ -MMD -MP -MF groupsock/GroupsockHelper.o.d.org -fpic -ffunction-sections -funwind-tables -fstack-protector -D__ARM_ARCH_5__ -D__ARM_ARCH_5T__ -D__ARM_ARCH_5E__ -D__ARM_ARCH_5TE__ -Wno-psabi -march=armv5te -mtune=xscale -msoft-float -fno-exceptions -fno-rtti -mthumb -Os -fomit-frame-pointer -fno-strict-aliasing -finline- limit=64 -Igroupsock/include -Igroupsock/../UsageEnvironment/include -Iandroid- ndk-r5b/sources/cxx-stl/system/include -Igroupsock -DANDROID -Wa,--noexecstack -DANDROID_NDK -Wall -fexceptions -O2 -DNDEBUG -g -Iandroid-8/arch-arm/usr/include -c groupsock/GroupsockHelper.cpp -o groupsock/GroupsockHelper.o && rm -f groupsock/GroupsockHelper.o.d && mv groupsock/GroupsockHelper.o.d.org groupsock/GroupsockHelper.o.d groupsock/GroupsockHelper.cpp: In function 'Boolean socketJoinGroupSSM(UsageEnvironment&, int, netAddressBits, netAddressBits)': groupsock/GroupsockHelper.cpp:427: error: request for member 's_addr' in 'imr.ip_mreq_source::imr_multiaddr', which is of non-class type '__u32' groupsock/GroupsockHelper.cpp:428: error: request for member 's_addr' in 'imr.ip_mreq_source::imr_sourceaddr', which is of non-class type '__u32' groupsock/GroupsockHelper.cpp:429: error: request for member 's_addr' in 'imr.ip_mreq_source::imr_interface', which is of non-class type '__u32' I am not sure what is causing the error. Any pointers would be great - no pun intended. Thanks

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• Optimizing processing and management of large Java data arrays

  - by mikera

  I'm writing some pretty CPU-intensive, concurrent numerical code that will process large amounts of data stored in Java arrays (e.g. lots of double[100000]s). Some of the algorithms might run millions of times over several days so getting maximum steady-state performance is a high priority. In essence, each algorithm is a Java object that has an method API something like: public double[] runMyAlgorithm(double[] inputData); or alternatively a reference could be passed to the array to store the output data: public runMyAlgorithm(double[] inputData, double[] outputData); Given this requirement, I'm trying to determine the optimal strategy for allocating / managing array space. Frequently the algorithms will need large amounts of temporary storage space. They will also take large arrays as input and create large arrays as output. Among the options I am considering are: Always allocate new arrays as local variables whenever they are needed (e.g. new double[100000]). Probably the simplest approach, but will produce a lot of garbage. Pre-allocate temporary arrays and store them as final fields in the algorithm object - big downside would be that this would mean that only one thread could run the algorithm at any one time. Keep pre-allocated temporary arrays in ThreadLocal storage, so that a thread can use a fixed amount of temporary array space whenever it needs it. ThreadLocal would be required since multiple threads will be running the same algorithm simultaneously. Pass around lots of arrays as parameters (including the temporary arrays for the algorithm to use). Not good since it will make the algorithm API extremely ugly if the caller has to be responsible for providing temporary array space.... Allocate extremely large arrays (e.g. double[10000000]) but also provide the algorithm with offsets into the array so that different threads will use a different area of the array independently. Will obviously require some code to manage the offsets and allocation of the array ranges. Any thoughts on which approach would be best (and why)?

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• Custom Calculations in a Matrix - Reporting Services 2005

  - by bfrancis

  I am writing a report to show gas usage (in gallons) used by each department. The request is to view each month and the gallons used by each department. A column is required to display what each departments target goal is, based on the gallons of gas they have used in a past time frame. Each departments target goal is x percent less than the total gallons used for said time frame. I currently have a matrix in Reporting Services with departments making up rows, months making up columns, and gallons filling the details. The matrix is being filled by dataset1. I have the data grouping as is requested for each month by each department. My problem is calculating the target goal. My thought was to create a second dataset (dataset2) that returns the gallons used based on the time frame requested. I grouped this data by department. I was hoping I could use the department field in each dataset to make sure the appropriate numbers were used. I added a new column which shows up next to the gallons field. As I attempted to build the Expression I found out that I could only grab the gallons used from dataset2 if I was summing the gallons field. This gives me the total gallons used by every department combined. I have tried to find resources with similar examples of what I am trying to accomplish but I cannot seem to come across one. I am trying to keep this as detailed as possible without making it too wordy. I would be more than happy to clarify or explain into further detail what I have written above if it is needed. If anyone has links, comments, or suggestions they would be greatly appreciated. A very simple visual or what I am hoping to accomplish is below. The months and departments would expand based on the data returned. months ------------------------------ departments| gallons/month | target goal

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• Book recommendation for Silverlight

  - by Mathias Weyel

  Hi there, yet another question for recommendations for a book on Silverlight. I look for a book that covers the UI and styling and, if possible, custom drawing and graphics. Very important for me is the style of the book - it should focus on the actual programming and not on where to click in Visual Studio to get things done. Let's take a fictional example for proper usage of the DataGrid control: Bad: To use the data grid, drag it from the toolbox onto the control. You can change the background color by clicking on “Background” in the properties. To define custom columns, click on columns and edit them in the configuration window that opens. Good: To use the DataGrid, you need a reference to the blah dll and declare the namespace in the XAML like this (blah), the data model should be like blah and if you want to define how the columns look like, you need to define them like this (more blah). And if you want to do this in C# because you for whatever reason aren’t able or willing to use XAML, this would look like blah. Bonus points for coverage of topics like how to manage resources (images/fonts) and internationalization. There are quite some snippets on how to do that on the internet but somehow each of them looks like they work but are not a proper way of doing it. cheers Mathias

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• iPhone - Memory Management - Using Leaks tool and getting some bizarre readings.

  - by Robert

  Hey all, putting the finishing touches on a project of mine so I figured I would run through it and see if and where I had any memory leaks. Found and fixed most of them but there are a couple of things regarding the memory leaks and object alloc that I am confused about. 1) There are 2 memory leaks that do not show me as responsible. There are 8 leaks attributed to AudioToolbox with the function being RegisterEmbeddedAudioCodecs(). This accounts for about 1.5 kb of leaks. The other one is detected immediately when the app begins. Core Graphics is responsible with the extra info being open_handle_to_dylib_path. For the audio leak I have looked over my audio code and to me it seems ok. self.musicPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL fileURLWithPath:songFilePath] error:NULL]; [musicPlayer prepareToPlay]; [musicPlayer play] is called later on in a function. 2) Is it normal for there to be a spike in Object Allocation whenever a new view or controller is presented? My total memory usage is very, very low except for whenever I present a view controller. It spikes then immediately goes back down. I am guessing that this is just the phone handling all the information for switching or something. Blegh. Wall of text. Thanks in advance to anyone who helps! =)

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• Creating a property setter delegate

  - by Jim C

  I have created methods for converting a property lambda to a delegate: public static Delegate MakeGetter<T>(Expression<Func<T>> propertyLambda) { var result = Expression.Lambda(propertyLambda.Body).Compile(); return result; } public static Delegate MakeSetter<T>(Expression<Action<T>> propertyLambda) { var result = Expression.Lambda(propertyLambda.Body).Compile(); return result; } These work: Delegate getter = MakeGetter(() => SomeClass.SomeProperty); object o = getter.DynamicInvoke(); Delegate getter = MakeGetter(() => someObject.SomeProperty); object o = getter.DynamicInvoke(); but these won't compile: Delegate setter = MakeSetter(() => SomeClass.SomeProperty); setter.DynamicInvoke(new object[]{propValue}); Delegate setter = MakeSetter(() => someObject.SomeProperty); setter.DynamicInvoke(new object[]{propValue}); The MakeSetter lines fail with "The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly." Is what I'm trying to do possible? Thanks in advance.

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• Can the Singleton be replaced by Factory?

  - by lostiniceland

  Hello Everyone There are already quite some posts about the Singleton-Pattern around, but I would like to start another one on this topic since I would like to know if the Factory-Pattern would be the right approach to remove this "anti-pattern". In the past I used the singleton quite a lot, also did my fellow collegues since it is so easy to use. For example, the Eclipse IDE or better its workbench-model makes heavy usage of singletons as well. It was due to some posts about E4 (the next big Eclipse version) that made me start to rethink the singleton. The bottom line was that due to this singletons the dependecies in Eclipse 3.x are tightly coupled. Lets assume I want to get rid of all singletons completely and instead use factories. My thoughts were as follows: hide complexity less coupling I have control over how many instances are created (just store the reference I a private field of the factory) mock the factory for testing (with Dependency Injection) when it is behind an interface In some cases the factories can make more than one singleton obsolete (depending on business logic/component composition) Does this make sense? If not, please give good reasons for why you think so. An alternative solution is also appreciated. Thanks Marc

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• Which language should I use to program a GUI application?

  - by Roman

  I would like to write a GUI application for management of information (text documents). In more details, it should be similar to the TiddlyWiki. I would like to have there some good visual effects (like nice representation for three structures, which you can rotate, some sound). I also would like to include some communication via Internet (for sharing and collaboration). In should include some features of such applications as a web browser, word processor, Skype. Which programming language should I use? I like the idea of usage of JavaScripts (like TddlyWiki). The good thing about that, is that user should not install anything. They open a file in a browser and it works! The bad thing is that JavaScript cannot communicate via internet with other applications. I think the choice of the programming language, in my case, id conditioned by 2 things: What can be done with this programming language (which restrictions are there). How easy to program. I would like to have "block" which can do a lot of things (rather than to program then and, in this way, to "rediscover a bicycle") ADDED: I would like to make it platform independent.

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