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  • Function Returning Negative Value

    - by Geowil
    I still have not run it through enough tests however for some reason, using certain non-negative values, this function will sometimes pass back a negative value. I have done a lot of manual testing in calculator with different values but I have yet to have it display this same behavior. I was wondering if someone would take a look at see if I am missing something. float calcPop(int popRand1, int popRand2, int popRand3, float pERand, float pSRand) { return ((((((23000 * popRand1) * popRand2) * pERand) * pSRand) * popRand3) / 8); } The variables are all contain randomly generated values: popRand1: between 1 and 30 popRand2: between 10 and 30 popRand3: between 50 and 100 pSRand: between 1 and 1000 pERand: between 1.0f and 5500.0f which is then multiplied by 0.001f before being passed to the function above Edit: Alright so after following the execution a bit more closely it is not the fault of this function directly. It produces an infinitely positive float which then flips negative when I use this code later on: pPMax = (int)pPStore; pPStore is a float that holds popCalc's return. So the question now is, how do I stop the formula from doing this? Testing even with very high values in Calculator has never displayed this behavior. Is there something in how the compiler processes the order of operations that is causing this or are my values simply just going too high? If the later I could just increase the division to 16 I think.

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  • trouble connecting to MySql DB (PHP)

    - by user332817
    Hi I have the following PHP code to connect to my db. <?php ob_start(); $host="localhost"; // Host name $username="root"; // Mysql username $password=""; // Mysql password $db_name="test"; // Database name $tbl_name="members"; // Table name // Connect to server and select databse. mysql_connect("$host", "$username", "$password")or die("cannot connect"); ?> however I get the following error: Warning: mysql_connect() [function.mysql-connect]: [2002] A connection attempt failed because the connected party did not (trying to connect via tcp://localhost:3306) in C:\Program Files (x86)\EasyPHP-5.3.2i\www\checklogin.php on line 11 Warning: mysql_connect() [function.mysql-connect]: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. in C:\Program Files (x86)\EasyPHP-5.3.2i\www\checklogin.php on line 11 Fatal error: Maximum execution time of 30 seconds exceeded in C:\Program Files (x86)\EasyPHP-5.3.2i\www\checklogin.php on line 11 I am able to add a db/tables via phpmyadmin but I cant connect using php. here is a screenshot of my phpmyadmin page: http://img294.imageshack.us/img294/1589/sqls.jpg any help would be appreciated, thanks in advance.

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  • reporting tool/viewer for large datasets

    - by FrustratedWithFormsDesigner
    I have a data processing system that generates very large reports on the data it processes. By "large" I mean that a "small" execution of this system produces about 30 MB of reporting data when dumped into a CSV file and a large dataset is about 130-150 MB (I'm sure someone out there has a bigger idea of "large" but that's not the point... ;) Excel has the ideal interface for the report consumers in the form of its Data Lists: users can filter and segment the data on-the-fly to see the specific details that they are interested in - they can also add notes and markup to the reports, create charts, graphs, etc... They know how to do all this and it's much easier to let them do it if we just give them the data. Excel was great for the small test datasets, but it cannot handle these large ones. Does anyone know of a tool that can provide a similar interface as Excel data lists, but that can handle much larger files? The next tool I tried was MS Access, and found that the Access file bloats hugely (30 MB input file leads to about 70 MB Access file, and when I open the file, run a report and close it the file's at 120-150 MB!), the import process is slow and very manual (currently, the CSV files are created by the same plsql script that runs the main process so there's next to no intervention on my part). I also tried an Access database with linked tables to the database tables that store the report data and that was many times slower (for some reason, sqlplus could query and generate the report file in a minute or soe while Access would take anywhere from 2-5 minutes for the same data) (If it helps, the data processing system is written in PL/SQL and runs on Oracle 10g.)

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  • C/C++ I18N mbstowcs question

    - by bogertron
    I am working on internationalizing the input for a C/C++ application. I have currently hit an issue with converting from a multi-byte string to wide character string. The code needs to be cross platform compatible, so I am using mbstowcs and wcstombs as much as possible. I am currently working on a WIN32 machine and I have set the locale to a non-english locale (Japanese). When I attempt to convert a multibyte character string, I seem to be having some conversion issues. Here is an example of the code: int main(int argc, char** argv) { wchar_t *wcsVal = NULL; char *mbsVal = NULL; /* Get the current code page, in my case 932, runs only on windows */ TCHAR szCodePage[10]; int cch= GetLocaleInfo( GetSystemDefaultLCID(), LOCALE_IDEFAULTANSICODEPAGE, szCodePage, sizeof(szCodePage)); /* verify locale is set */ if (setlocale(LC_CTYPE, "") == 0) { fprintf(stderr, "Failed to set locale\n"); return 1; } mbsVal = argv[1]; /* validate multibyte string and convert to wide character */ int size = mbstowcs(NULL, mbsVal, 0); if (size == -1) { printf("Invalid multibyte\n"); return 1; } wcsVal = (wchar_t*) malloc(sizeof(wchar_t) * (size + 1)); if (wcsVal == NULL) { printf("memory issue \n"); return 1; } mbstowcs(wcsVal, szVal, size + 1); wprintf(L"%ls \n", wcsVal); return 0; } At the end of execution, the wide character string does not contain the converted data. I believe that there is an issue with the code page settings, because when i use MultiByteToWideChar and have the current code page sent in EX: MultiByteToWideChar( CP_ACP, 0, mbsVal, -1, wcsVal, size + 1 ); in place of the mbstowcs calls, the conversion succeeds. My question is, how do I use the generic mbstowcs call instead of teh MuliByteToWideChar call?

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  • Why is my code stopping and not returning an exception?

    - by BeckyLou
    I have some code that starts a couple of threads to let them execute, then uses a while loop to check for the current time passing a set timeout period, or for the correct number of results to have been processed (by checking an int on the class object) (with a Thread.Sleep() to wait between loops) Once the while loop is set to exit, it calls Abort() on the threads and should return data to the function that calls the method. When debugging and stepping through the code, I find there can be exceptions in the code running on the separate threads, and in some cases I handle these appropriately, and at other times I don't want to do anything specific. What I have been seeing is that my code goes into the while loop and the thread sleeps, then nothing is returned from my function, either data or an exception. Code execution just stops completely. Any ideas what could be happening? Code sample: System.Threading.Thread sendThread = new System.Threading.Thread(new System.Threading.ThreadStart(Send)); sendThread.Start(); System.Threading.Thread receiveThread = new System.Threading.Thread(new System.Threading.ThreadStart(Receive)); receiveThread.Start(); // timeout Int32 maxSecondsToProcess = this.searchTotalCount * timeout; DateTime timeoutTime = DateTime.Now.AddSeconds(maxSecondsToProcess); Log("Submit() Timeout time: " + timeoutTime.ToString("yyyyMMdd HHmmss")); // while we're still waiting to receive results & haven't hit the timeout, // keep the threads going while (resultInfos.Count < this.searchTotalCount && DateTime.Now < timeoutTime) { Log("Submit() Waiting..."); System.Threading.Thread.Sleep(10 * 1000); // 1 minute } Log("Submit() Aborting threads"); // <== this log doesn't show up sendThread.Abort(); receiveThread.Abort(); return new List<ResultInfo>(this.resultInfos.Values);

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  • Android Signal 11 (SIGSEGV)

    - by Naturjoghurt
    I read many posts here and on other sites, but can not find the problem creating my Error: I use an AsyncTask because I want to easily manipulate the UI Thread before and after Execution. In doInBackground I create a ThreadPoolExecutor and execute Runnables. If I only execute 1 Runnable with the Executor, there is no Problem, but if I execute another Runnable I get following Error: 06-26 18:00:42.288: A/libc(25073): Fatal signal 11 (SIGSEGV) at 0x7f486162 (code=1), thread 25106 (pool-1-thread-2) 06-26 18:00:42.304: D/dalvikvm(25073): GC_CONCURRENT freed 119K, 2% free 8908K/9056K, paused 4ms+4ms, total 45ms 06-26 18:00:42.327: I/System.out(25073): In Check All with Prefix: a and Length: 4 06-26 18:00:42.390: I/DEBUG(126): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** 06-26 18:00:42.390: I/DEBUG(126): Build fingerprint: 'google/yakju/maguro:4.2.2/JDQ39/573038:user/release-keys' 06-26 18:00:42.390: I/DEBUG(126): Revision: '9' 06-26 18:00:42.390: I/DEBUG(126): pid: 25073, tid: 25106, name: pool-1-thread-2 >>> de.uni_duesseldorf.cn.distributed_computing2 <<< 06-26 18:00:42.390: I/DEBUG(126): signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 7f486162 ... 06-26 18:00:42.538: I/DEBUG(126): memory map around fault addr 7f486162: 06-26 18:00:42.538: I/DEBUG(126): 60292000-60391000 06-26 18:00:42.538: I/DEBUG(126): (no map for address) 06-26 18:00:42.538: I/DEBUG(126): bed14000-bed35000 [stack] I set up the ThreadPoolExecutor like this: // numberOfPackages: Number of Runnables to be executed public void initializeThreadPoolExecutor (int numberOfPackages) { int corePoolSize = Runtime.getRuntime().availableProcessors(); int maxPoolSize = numberOfPackages; long keepAliveTime = 60; final BlockingQueue workingQueue = new LinkedBlockingQueue(); executor = new ThreadPoolExecutor(corePoolSize, maxPoolSize, keepAliveTime, TimeUnit.SECONDS, workingQueue); } I have no clue, why it fails when starting the second Thread. Maybe Memory Leaks? Any Help appreciated. Thanks in Advance

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  • getting another website data to manipulate it's value in perl

    - by aun ali
    use CGI qw(:standard); use CGI::Carp qw(fatalsToBrowser warningsToBrowser); our @a=param(src="http://fxrates.forexpros.com/index.php?pairs_ids=1525=last_update"); print header(),start_html('results.pl'); $a=http://fxrates.forexpros.com/index.php?pairs_ids=1525=last_update; '<iframe frameborder="0" scrolling="no" height="95" width="213" allowtransparency="true" marginwidth="0" marginheight="0" src="http://fxrates.forexpros.com/index.php?pairs_ids=1525;&header-text-color=%23FFFFFF&curr-name-color=%230059b0&inner-text-color=%23000000&green-text-color=%232A8215&green-background=%23B7F4C2&red-text-color=%23DC0001&red-background=%23FFE2E2&inner-border-color=%23CBCBCB&border-color=%23cbcbcb&bg1=%23F6F6F6&bg2=%23ffffff&bid=hide&ask=hide&last=hide&high=hide&low=hide&change=hide&change_in_percents=hide&last_update=show"></iframe><br /><div style="width:213"><span style="float:left"><span style="font-size: 11px;color: #333333;text-decoration: none;">The <a href="http://www.forexpros.com/quotes" target="_blank" style="font-size: 11px;color: #06529D; font-weight: bold;" class="underline_link">Forex Quotes</a> are Powered by Forexpros - The Leading Financial Portal.</span></span></div>'; print '<br/>'; print "$a"; print end_html();' getting error: Can't modify constant item in scalar assignment at livedata.pl line 4, near ""http://fxrates.forexpros.com/index.php?pairs_ids=1525=last_update")" syntax error at livedata.pl line 6, near "http:" Execution of livedata.pl aborted due to compilation errors.

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  • Inline function v. Macro in C -- What's the Overhead (Memory/Speed)?

    - by Jason R. Mick
    I searched Stack Overflow for the pros/cons of function-like macros v. inline functions. I found the following discussion: Pros and Cons of Different macro function / inline methods in C ...but it didn't answer my primary burning question. Namely, what is the overhead in c of using a macro function (with variables, possibly other function calls) v. an inline function, in terms of memory usage and execution speed? Are there any compiler-dependent differences in overhead? I have both icc and gcc at my disposal. My code snippet I'm modularizing is: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = AttractiveTerm * AttractiveTerm; EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); My reason for turning it into an inline function/macro is so I can drop it into a c file and then conditionally compile other similar, but slightly different functions/macros. e.g.: double AttractiveTerm = pow(SigmaSquared/RadialDistanceSquared,3); double RepulsiveTerm = pow(SigmaSquared/RadialDistanceSquared,9); EnergyContribution += 4 * Epsilon * (RepulsiveTerm - AttractiveTerm); (note the difference in the second line...) This function is a central one to my code and gets called thousands of times per step in my program and my program performs millions of steps. Thus I want to have the LEAST overhead possible, hence why I'm wasting time worrying about the overhead of inlining v. transforming the code into a macro. Based on the prior discussion I already realize other pros/cons (type independence and resulting errors from that) of macros... but what I want to know most, and don't currently know is the PERFORMANCE. I know some of you C veterans will have some great insight for me!!

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  • Urgent Help not showing the grid on the page..

    - by kumar
    hello Friends, I have two user controlers 1) name.ascx 2) friends.ascx in both controlers Code is same just changing the Grid name and columns but URL pointing is differnt.. <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<JQGridMVCExamples.Models.OrdersJqGridModel>" %> <div> <%= Html.Trirand().JQGrid(Model.OrdersGrid, "JQGrid1") %> </div> <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<JQGridMVCExamples.Models.OrdersJqGridModel2>" %> <div> <%= Html.Trirand().JQGrid(Model.OrdersGrid2, "JQGrid2") %> </div> But what hapeening is for second gri JQGrid2 is not showing up.. but First Grid is showing.. when i do first time second grid execution is not shoiwng up but when I do after first grid.. I am getting the result but Frist grid columns I am getting not the second grid columns.. can any body have sujjestion on this? thanks

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  • php script randomly hangs up

    - by sergdev
    I install php 5 (more precisely 5.3.1) as apache module. After this one of my application becomes randomly hang up on mysql_connect - sometimes works, sometimes no, sometimes reload of page helps. How can this be fixed? I use Windows Vista, Apache/2.2.14 (Win32) PHP/5.3.1 with php module, MySql 5.0.67-community-nt. After a minute I obtain the error message: Fatal error: Maximum execution time of 60 seconds exceeded in path\to\mysqlcon.php on line 9 I run MySql locally and heavy load could not be a reason: SHOW PROCESSLIST shows about 3 process SHOW VARIABLES LIKE 'MAX_CONNECTIONS' is 100. UPDATE: At first I thought that this is connected with mysql_connect. But now I can't say for certain. More difficult thing is when I insert the line to debug: $fh = fopen("E://_debugLog", 'a'); fwrite($fh, __FILE__ . " : " . __LINE__ . "\n"); fclose($fh); script start working near that location as a rule.

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  • Spring Dependency Injecting an annotated Aspect

    Using Spring I've had some issues with doing a dependency injection on an annotated Aspect class. CacheService is injected upon the Spring context's startup, but when the weaving takes place, it says that the cacheService is null. So I am forced to relook up the spring context manually and get the bean from there. Is there another way of going about it? Here is an example of my Aspect: import org.apache.log4j.Logger; import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import com.mzgubin.application.cache.CacheService; @Aspect public class CachingAdvice { private static Logger log = Logger.getLogger(CachingAdvice.class); private CacheService cacheService; @Around("execution(public *com.mzgubin.application.callMethod(..)) &&" + "args(params)") public Object addCachingToCreateXMLFromSite(ProceedingJoinPoint pjp, InterestingParams params) throws Throwable { log.debug("Weaving a method call to see if we should return something from the cache or create it from scratch by letting control flow move on"); Object result = null; if (getCacheService().objectExists(params))}{ result = getCacheService().getObject(params); } else { result = pjp.proceed(pjp.getArgs()); getCacheService().storeObject(params, result); } return result; } public CacheService getCacheService(){ return cacheService; } public void setCacheService(CacheService cacheService){ this.cacheService = cacheService; } }

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  • PHP Object Creation and Memory Usage

    - by JohnO
    A basic dummy class: class foo { var $bar = 0; function foo() {} function boo() {} } echo memory_get_usage(); echo "\n"; $foo = new foo(); echo memory_get_usage(); echo "\n"; unset($foo); echo memory_get_usage(); echo "\n"; $foo = null; echo memory_get_usage(); echo "\n"; Outputs: $ php test.php 353672 353792 353792 353792 Now, I know that PHP docs say that memory won't be freed until it is needed (hitting the ceiling). However, I wrote this up as a small test, because I've got a much longer task, using a much bigger object, with many instances of that object. And the memory just climbs, eventually running out and stopping execution. Even though these large objects do take up memory, since I destroy them after I'm done with each one (serially), it should not run out of memory (unless a single object exhausts the entire space for memory, which is not the case). Thoughts?

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  • GridView ObjectDataSource LINQ Paging and Sorting using multiple table query.

    - by user367426
    I am trying to create a pageing and sorting object data source that before execution returns all results, then sorts on these results before filtering and then using the take and skip methods with the aim of retrieving just a subset of results from the database (saving on database traffic). this is based on the following article: http://www.singingeels.com/Blogs/Nullable/2008/03/26/Dynamic_LINQ_OrderBy_using_String_Names.aspx Now I have managed to get this working even creating lambda expressions to reflect the sort expression returned from the grid even finding out the data type to sort for DateTime and Decimal. public static string GetReturnType<TInput>(string value) { var param = Expression.Parameter(typeof(TInput), "o"); Expression a = Expression.Property(param, "DisplayPriceType"); Expression b = Expression.Property(a, "Name"); Expression converted = Expression.Convert(Expression.Property(param, value), typeof(object)); Expression<Func<TInput, object>> mySortExpression = Expression.Lambda<Func<TInput, object>>(converted, param); UnaryExpression member = (UnaryExpression)mySortExpression.Body; return member.Operand.Type.FullName; } Now the problem I have is that many of the Queries return joined tables and I would like to sort on fields from the other tables. So when executing a query you can create a function that will assign the properties from other tables to properties created in the partial class. public static Account InitAccount(Account account) { account.CurrencyName = account.Currency.Name; account.PriceTypeName = account.DisplayPriceType.Name; return account; } So my question is, is there a way to assign the value from the joined table to the property of the current table partial class? i have tried using. from a in dc.Accounts where a.CompanyID == companyID && a.Archived == null select new { PriceTypeName = a.DisplayPriceType.Name}) but this seems to mess up my SortExpression. Any help on this would be much appreciated, I do understand that this is complex stuff.

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  • FluentNHibernate error -- "Invalid object name"

    - by goober
    I'm attempting to do the most simple of mappings with FluentNHibernate & Sql2005. Basically, I have a database table called "sv_Categories". I'd like to add a category, setting the ID automatically, and adding the userid and title supplied. Database table layout: CategoryID -- int -- not-null, primary key, auto-incrementing UserID -- uniqueidentifier -- not null Title -- varchar(50) -- not null Simple. My SessionFactory code (which works, as far as I can tell): _SessionFactory = Fluently.Configure().Database( MsSqlConfiguration.MsSql2005 .ConnectionString(c => c.FromConnectionStringWithKey("SVTest"))) .Mappings(x => x.FluentMappings.AddFromAssemblyOf<CategoryMap>()) .BuildSessionFactory(); My ClassMap code: public class CategoryMap : ClassMap<Category> { public CategoryMap() { Id(x => x.ID).Column("CategoryID").Unique(); Map(x => x.Title).Column("Title").Not.Nullable(); Map(x => x.UserID).Column("UserID").Not.Nullable(); } } My Class code: public class Category { public virtual int ID { get; private set; } public virtual string Title { get; set; } public virtual Guid UserID { get; set; } public Category() { // do nothing } } And the page where I save the object: public void Add(Category catToAdd) { using (ISession session = SessionProvider.GetSession()) { using (ITransaction Transaction = session.BeginTransaction()) { session.Save(catToAdd); Transaction.Commit(); } } } I receive the error Invalid object name 'Category'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: Invalid object name 'Category'. I think it might be that I haven't told the CategoryMap class to use the "sv_Categories" table, but I'm not sure how to do that. Any help would be appreciated. Thanks!

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  • Time gaps between host clEnqueue_xxx calls

    - by dialer
    Consider these OpenCL calls (3 memcpy DtoH, 4313 cl_float elements each): clEnqueueReadBuffer(CommandQueue, SpectrumAbsMem, CL_FALSE, 0, SpectrumMemSize, SpectrumAbs, 0, NULL, NULL); clEnqueueReadBuffer(CommandQueue, SpectrumReMem, CL_FALSE, 0, SpectrumMemSize, SpectrumRe, 0, NULL, NULL); clEnqueueReadBuffer(CommandQueue, SpectrumImMem, CL_FALSE, 0, SpectrumMemSize, SpectrumIm, 0, NULL, NULL); When I analyze these with the NVIDIA visual profiler, I see that the actual memcpy operation only takes 8 us, but there is a significant gap of around 130 us after each memcpy. I'm already using the supposedly asynchronous method (the CL_FALSE in the argument list). When I use only one operation, but with three times the size, the operation is way faster. Why is the time gap between the actual memcpy operations so huge, whereas the gap between the kernel execution (exactly before these three operations) and the first memcpy is only 7us? Can I get rid of it, or do I need to accumulate more data before starting a memcpy? If so, is there a convenient way how I could combine mutliple arrays into a single contiguous block of memory, but still have a cl_mem object as a separate device memory pointer to each section?

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  • What wrapper class in C++ should I use for automated resource management?

    - by Vilx-
    I'm a C++ amateur. I'm writing some Win32 API code and there are handles and weirdly compositely allocated objects aplenty. So I was wondering - is there some wrapper class that would make resource management easier? For example, when I want to load some data I open a file with CreateFile() and get a HANDLE. When I'm done with it, I should call CloseHandle() on it. But for any reasonably complex loading function there will be dozens of possible exit points, not to mention exceptions. So it would be great if I could wrap the handle in some kind of wrapper class which would automatically call CloseHandle() once execution left the scope. Even better - it could do some reference counting so I can pass it around in and out of other functions, and it would release the resource only when the last reference left scope. The concept is simple - but is there something like that in the standard library? I'm using Visual Studio 2008, by the way, and I don't want to attach a 3rd party framework like Boost or something.

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  • Why Is Apache Giving 403?

    - by ThinkCL
    I am getting 403 Errors from Apache when I send too many, 12, synchronous HTTP Posts via a desktop app I am building in XCode / Objective-C. The 12 POST requests are just a few kb each and go out instantly one after the other and the Apache Error Log shows... client denied by server configuration: /the-path/the-file.php Apache 2.0 PHP 5 and I have this same setup working fine on my local machine. The error is coming from a VPS with my host, which runs very fast and smooth and has plenty of resources. To debug I threw a sleep(1); function (stalls script execution by 1 second) into the php file and that fixed it. This makes me think that I am breaking some limit for too many requests for a single IP in a certain amount of time. I have googled and combed PHP ini and Apache configs, but I cannot find what that directive/setting might be. I should mention that the although it varies the first 4 or 5 POSTS usually work then it starts returning the 403 error intermittently after that. Just really acting like its bogging down. Any ideas?

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  • Efficiently select top row for each category in the set

    - by VladV
    I need to select a top row for each category from a known set (somewhat similar to this question). The problem is, how to make this query efficient on the large number of rows. For example, let's create a table that stores temperature recording in several places. CREATE TABLE #t ( placeId int, ts datetime, temp int, PRIMARY KEY (ts, placeId) ) -- insert some sample data SET NOCOUNT ON DECLARE @n int, @ts datetime SELECT @n = 1000, @ts = '2000-01-01' WHILE (@n>0) BEGIN INSERT INTO #t VALUES (@n % 10, @ts, @n % 37) IF (@n % 10 = 0) SET @ts = DATEADD(hour, 1, @ts) SET @n = @n - 1 END Now I need to get the latest recording for each of the places 1, 2, 3. This way is efficient, but doesn't scale well (and looks dirty). SELECT * FROM ( SELECT TOP 1 placeId, temp FROM #t WHERE placeId = 1 ORDER BY ts DESC ) t1 UNION ALL SELECT * FROM ( SELECT TOP 1 placeId, temp FROM #t WHERE placeId = 2 ORDER BY ts DESC ) t2 UNION ALL SELECT * FROM ( SELECT TOP 1 placeId, temp FROM #t WHERE placeId = 3 ORDER BY ts DESC ) t3 The following looks better but works much less efficiently (30% vs 70% according to the optimizer). SELECT placeId, ts, temp FROM ( SELECT placeId, ts, temp, ROW_NUMBER() OVER (PARTITION BY placeId ORDER BY ts DESC) rownum FROM #t WHERE placeId IN (1, 2, 3) ) t WHERE rownum = 1 The problem is, during the latter query execution plan a clustered index scan is performed on #t and 300 rows are retrieved, sorted, numbered, and then filtered, leaving only 3 rows. For the former query three times one row is fetched. Is there a way to perform the query efficiently without lots of unions?

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  • Preprocessor #define vs. function pointer - best practice?

    - by Dustin
    I recently started a small personal project (RGB value to BGR value conversion program) in C, and I realised that a function that converts from RGB to BGR can not only perform the conversion but also the inversion. Obviously that means I don't really need two functions rgb2bgr and bgr2rgb. However, does it matter whether I use a function pointer instead of a macro? For example: int rgb2bgr (const int rgb); /* * Should I do this because it allows the compiler to issue * appropriate error messages using the proper function name, * not to mention possible debugging benefits? */ int (*bgr2rgb) (const int bgr) = rgb2bgr; /* * Or should I do this since it is merely a convenience * and they're really the same function anyway? */ #define bgr2rgb(bgr) (rgb2bgr (bgr)) I'm not necessarily looking for a change in execution efficiency as it's more of a subjective question out of curiosity. I am well aware of the fact that type safety is neither lost nor gained using either method. Would the function pointer merely be a convenience or are there more practical benefits to be gained of which I am unaware?

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  • Using struts 2 with no tags

    - by WannaAsk
    Hi everyone, I wonder if you could guide me on this struts issue - I feel hopeless on this... I am working on migrating our web application to a Struts 2 portlet (I'm using Struts 2.1.8). The thing is, I am forced to avoid struts tags because our application relies on Dijit widgets, which are omitted when using struts tags. So now I should implement the <s:form tag using scriptlets. My question is: how you would suggest I imitate the way struts handles the "action" attribute? Right now it appears I should: Create a regular html form in my jsp. Get/create the ActionConfig object during onsubmit and set on it values which match my desired destination: class+method+result jsp. Execute the action I set in 2. Would you recommend this? If so - is ActionConfig obtained from the session? Can I initiate an action execution from ActionConfig? (Aletrnatively... generating an action url using struts' form.vm file - what do you say?) I would appreciate any help on this - Thanks a lot in advance!!!

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  • Recommendations for IPC between parent and child processes in .NET?

    - by Jeremy
    My .NET program needs to run an algorithm that makes heavy use of 3rd party libraries (32-bit), most of which are unmanaged code. I want to drive the CPU as hard as I can, so the code runs several threads in parallel to divide up the work. I find that running all these threads simultaneously results in temporary memory spikes, causing the process' virtual memory size to approach the 2 GB limit. This memory is released back pretty quickly, but occasionally if enough threads enter the wrong sections of code at once, the process crosses the "red line" and either the unmanaged code or the .NET code encounters an out of memory error. I can throttle back the number of threads but then my CPU usage is not as high as I would like. I am thinking of creating worker processes rather than worker threads to help avoid the out of memory errors, since doing so would give each thread of execution its own 2 GB of virtual address space (my box has lots of RAM). I am wondering what are the best/easiest methods to communicate the input and output between the processes in .NET? The file system is an obvious choice. I am used to shared memory, named pipes, and such from my UNIX background. Is there a Windows or .NET specific mechanism I should use?

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  • What is a modern C++ approach to structures containing symbolic constants?

    - by Ken
    enum bool { FALSE = 0, TRUE = 1 }; I'm wondering how to translate this in a modern C++ approach and if there is a well suited container for that; i know that the enum are not really that appreciated, but i can't think about a real alternative in the C++ world. What if would like to associate the execution of a particular method with a state? Ok, this is the part where i will be more verbose. I would like to stress the fact that i'm asking about structures symbolic constants and not about TRUE and FALSE, i'm not that "needy". Suppose that i have a structure that can represent several states with their own constants enum semaphore { GREEN = 0, ORANGE = 1, RED = 2 }; this is C code, now my question is about how to do the same in C++ if there is a better way. My question continue when i ask about the possibility to do something like an automatic triggering when a change of state will occur, for example: int main{ ... semaphore = 1; ... } and without any extra statements this has to trigger a method() just because the semaphore is now orange. I hope that is more clear now.

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  • Slow query. Wrong database structure?

    - by Tin
    I have a database with table that contains tasks. Tasks have a lifecycle. The status of the task's lifecycle can change. These state transitions are stored in a separate table tasktransitions. Now I wrote a query to find all open/reopened tasks and recently changed tasks but I already see with a rather small number of tasks (<1000) that execution time has becoming very long (0.5s). Tasks +-------------+---------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------+------+-----+---------+----------------+ | taskid | int(11) | NO | PRI | NULL | auto_increment | | description | text | NO | | NULL | | +-------------+---------+------+-----+---------+----------------+ Tasktransitions +------------------+-----------+------+-----+-------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +------------------+-----------+------+-----+-------------------+----------------+ | tasktransitionid | int(11) | NO | PRI | NULL | auto_increment | | taskid | int(11) | NO | MUL | NULL | | | status | int(11) | NO | MUL | NULL | | | description | text | NO | | NULL | | | userid | int(11) | NO | | NULL | | | transitiondate | timestamp | NO | | CURRENT_TIMESTAMP | | +------------------+-----------+------+-----+-------------------+----------------+ Query SELECT tasks.taskid,tasks.description,tasklaststatus.status FROM tasks LEFT OUTER JOIN ( SELECT tasktransitions.taskid,tasktransitions.transitiondate,tasktransitions.status FROM tasktransitions INNER JOIN ( SELECT taskid,MAX(transitiondate) AS lasttransitiondate FROM tasktransitions GROUP BY taskid ) AS tasklasttransition ON tasklasttransition.lasttransitiondate=tasktransitions.transitiondate AND tasklasttransition.taskid=tasktransitions.taskid ) AS tasklaststatus ON tasklaststatus.taskid=tasks.taskid WHERE tasklaststatus.status IS NULL OR tasklaststatus.status=0 or tasklaststatus.transitiondate>'2013-09-01'; I'm wondering if the database structure is best choice performance wise. Could adding indexes help? I already tried to add some but I don't see great improvements. +-----------------+------------+----------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | +-----------------+------------+----------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | tasktransitions | 0 | PRIMARY | 1 | tasktransitionid | A | 896 | NULL | NULL | | BTREE | | | | tasktransitions | 1 | taskid_date_ix | 1 | taskid | A | 896 | NULL | NULL | | BTREE | | | | tasktransitions | 1 | taskid_date_ix | 2 | transitiondate | A | 896 | NULL | NULL | | BTREE | | | | tasktransitions | 1 | status_ix | 1 | status | A | 3 | NULL | NULL | | BTREE | | | +-----------------+------------+----------------+--------------+------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ Any other suggestions?

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  • Scheme Function to reverse elements of list of 2-list

    - by sudhirc
    This is an exercise from EOPL. Procedure (invert lst) takes lst which is a list of 2-lists and returns a list with each 2-list reversed. (define invert (lambda (lst) (cond((null? lst ) '()) ((= 2 (rtn-len (car lst))) ( cons(swap-elem (car lst)) (invert (cdr lst)))) ("List is not a 2-List")))) ;; Auxiliry Procedure swap-elements of 2 element list (define swap-elem (lambda (lst) (cons (car (cdr lst)) (car lst)))) ;; returns lengh of the list by calling (define rtn-len (lambda (lst) (calc-len lst 0))) ;; calculate length of the list (define calc-len (lambda (lst n) (if (null? lst) n (calc-len (cdr lst) (+ n 1))))) This seems to work however looks very verbose. Can this be shortened or written in more elegant way ? How I can halt the processing in any of the individual element is not a 2-list? At the moment execution proceed to next member and replacing current member with "List is not a 2-List" if current member is not a 2-list.

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  • Trouble tunneling my local Wordpress install to the mysql database on appfog

    - by alanmoo
    I've set up a wordpress install on appfog (using rackspace), and cloned the install to my local machine for development. I know the install works (using MAMP) because I created a local mysql database and changed wp-config.php to point to it. However, I want to develop without having to change wp-config.php every time I commit. After doing some research, it seems like the Appfog service Caldecott lets me tunnel into the mysql database on the server, using af tunnel. Unfortunately, I'm having issues with getting it working. Even if I change my MAMP mysql port to something like 8889, and tunnel mysql through port 3306, it looks like it's connected but I still get "Error establishing a database connection" when loading my localhost Wordpress. When I quit the mysql monitor (using ctrl+x, ctrl+c), I get a message stating "Error: 'mysql' execution failed; is it in your $PATH?'. Originally, no, it wasn't, but I've fixed my PATH variable on my local machine so that when I go to Terminal and just type mysql, it loads up. So I guess my question is 2 parts: 1.)Am I going with the right approach for Wordpress development on my local machine and 2.)If so, why is the tunnel not working?

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