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  • Can/should one disable namespace validation in Axis2 clients using ADB databinding?

    - by RJCantrell
    I have an document/literal Axis 1 service which I'm consuming with an Axis 2 client (ADB databinding, generated from WSDL2Java). It receives a valid XML response, but in parsing that XML, I get the error "Unexpected Subelement" for any type which doesn't have a namespace defined in the response. I can resolve the error by manually changing the (auto-generated by Axis2) type-validation line to only check the type name and not the namespace as well, but is there a non-manual way to skip this? This service is consumed properly by other Axis 1 clients. Here's the response, with bits in ALL CAPS having been anonymized. Some types have namespaces, some have empty-string namespaces, and some have none at all. Can I control this via the service's WSDL, or in Axis2's WSDL2Java handling of the WSDL? Is there a fundamental mismatch between Axis 1 and Axis2? The response below looks correct, except perhaps for where that type (anonymized as TWO below) is nested within itself. <?xml version="1.0" encoding="UTF-8"?> <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <soapenv:Body> <SERVICENAMEResponse xmlns="http://service.PROJECT.COMPANY.com"> <SERVICENAMEReturn xmlns=""> <ONE></ONE> <TWO><TWO> <THREE>2</THREE> <FOUR>-10</FOUR> <FIVE>6</FIVE> <SIX>1</SIX> </TWO></TWO> <fileName></fileName> </SERVICENAMEReturn></SERVICENAMEResponse> </soapenv:Body></soapenv:Envelope> I did not have to modify the validation of the "SERVICENAMEResponse" object because it has the correct namespace specified, but I have to so for all its subelements. The manual modification that I can make (one per type) to fix this is to change: if (reader.isStartElement() && new javax.xml.namespace.QName("http://dto.PROJECT.COMPANY.com","ONE").equals(reader.getName())){ to: if (reader.isStartElement() && new javax.xml.namespace.QName("ONE").equals(reader.getName())){

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  • Delphi - restore actual row in DBGrid

    - by durumdara
    Hi! D6 prof. Formerly we used DBISAM and DBISAMTable. That handle the RecNo, and it is working good with modifications (Delete, edit, etc). Now we replaced with ElevateDB, that don't handle RecNo, and many times we use Queries, not Tables. Query must reopen to see the modifications. But if we Reopen the Query, we need to repositioning to the last record. Locate isn't enough, because Grid is show it in another Row. This is very disturbing thing, because after the modification record is moving into another row, you hard to follow it, and users hate this. We found this code: function TBaseDBGrid.GetActRow: integer; begin Result := -1 + Row; end; procedure TBasepDBGrid.SetActRow(aRow: integer); var bm : TBookMark; begin if IsDataSourceValid(DataSource) then with DataSource.DataSet do begin bm := GetBookmark; DisableControls; try MoveBy(-aRow); MoveBy(aRow); //GotoBookmark(bm); finally FreebookMark(bm); EnableControls; end; end; end; The original example is uses moveby. This working good with Queries, because we cannot see that Query reopened in the background, the visual control is not changed the row position. But when we have EDBTable, or Live/Sensitive Query, the MoveBy is dangerous to use, because if somebody delete or append a new row, we can relocate into wrong record. Then I tried to use the BookMark (see remark). But this technique isn't working, because it is show the record in another Row position... So the question: how to force both the row position and record in DBGrid? Or what kind of DBGrid can relocate to the record/row after the underlying DataSet refreshed? I search for user friendly solution, I understand them, because I tried to use this jump-across DBGrid, and very bad to use, because my eyes are getting out when try to find the original record after update... :-( Thanks for your every help, link, info: dd

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  • tapestry 4 session expired

    - by cometta
    is below caused by user session expired? if yes, how to exend session on tapestry 4 ? or any other way to solve this problem? Unable to process client request: Unable to forward to local resource '/app?service=page&page=Home&id=692': java.lang.NullPointerException: Property 'webRequest' of <OuterProxy for tapestry.globals.RequestGlobals(org.apache.tapestry.services.RequestGlobals)> is null. Apr 22, 2010 5:14:43 PM org.apache.catalina.core.ApplicationContext log SEVERE: app: ServletException javax.servlet.ServletException: java.lang.NullPointerException: Property 'webRequest' of <OuterProxy for tapestry.globals.RequestGlobals(org.apache.tapestry.services.RequestGlobals)> is null. at org.apache.tapestry.services.impl.WebRequestServicerPipelineBridge.service(WebRequestServicerPipelineBridge.java:65) at $ServletRequestServicer_128043b52ea.service($ServletRequestServicer_128043b52ea.java) at org.apache.tapestry.request.DecodedRequestInjector.service(DecodedRequestInjector.java:55) at $ServletRequestServicerFilter_128043b52e6.service($ServletRequestServicerFilter_128043b52e6.java) at $ServletRequestServicer_128043b52ec.service($ServletRequestServicer_128043b52ec.java) at org.apache.tapestry.multipart.MultipartDecoderFilter.service(MultipartDecoderFilter.java:52) at $ServletRequestServicerFilter_128043b52e4.service($ServletRequestServicerFilter_128043b52e4.java) at $ServletRequestServicer_128043b52ec.service($ServletRequestServicer_128043b52ec.java) at org.apache.tapestry.services.impl.SetupRequestEncoding.service(SetupRequestEncoding.java:53) at $ServletRequestServicerFilter_128043b52e8.service($ServletRequestServicerFilter_128043b52e8.java) at $ServletRequestServicer_128043b52ec.service($ServletRequestServicer_128043b52ec.java) at $ServletRequestServicer_128043b52de.service($ServletRequestServicer_128043b52de.java) at org.apache.tapestry.ApplicationServlet.doService(ApplicationServlet.java:126) at org.apache.tapestry.ApplicationServlet.doPost(ApplicationServlet.java:171) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378) at org.springframework.security.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109) at org.springframework.security.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390) at org.springframework.security.ui.SessionFixationProtectionFilter.doFilterHttp(SessionFixationProtectionFilter.java:67) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390) at org.springframework.security.ui.ntlm.NtlmProcessingFilter.doFilterHttp(NtlmProcessingFilter.java:358) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390) at org.springframework.security.ui.ExceptionTranslationFilter.doFilterHttp(ExceptionTranslationFilter.java:101) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390) at org.springframework.security.context.HttpSessionContextIntegrationFilter.doFilterHttp(HttpSessionContextIntegrationFilter.java:235) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390) at org.springframework.security.concurrent.ConcurrentSessionFilter.doFilterHttp(ConcurrentSessionFilter.java:99) at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53) at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390) at org.springframework.security.util.FilterChainProxy.doFilter(FilterChainProxy.java:175) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:236) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:619)

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  • General advice and guidelines on how to properly override object.GetHashCode()

    - by Svish
    According to MSDN, a hash function must have the following properties: If two objects compare as equal, the GetHashCode method for each object must return the same value. However, if two objects do not compare as equal, the GetHashCode methods for the two object do not have to return different values. The GetHashCode method for an object must consistently return the same hash code as long as there is no modification to the object state that determines the return value of the object's Equals method. Note that this is true only for the current execution of an application, and that a different hash code can be returned if the application is run again. For the best performance, a hash function must generate a random distribution for all input. I keep finding myself in the following scenario: I have created a class, implemented IEquatable<T> and overridden object.Equals(object). MSDN states that: Types that override Equals must also override GetHashCode ; otherwise, Hashtable might not work correctly. And then it usually stops up a bit for me. Because, how do you properly override object.GetHashCode()? Never really know where to start, and it seems to be a lot of pitfalls. Here at StackOverflow, there are quite a few questions related to GetHashCode overriding, but most of them seems to be on quite particular cases and specific issues. So, therefore I would like to get a good compilation here. An overview with general advice and guidelines. What to do, what not to do, common pitfalls, where to start, etc. I would like it to be especially directed at C#, but I would think it will work kind of the same way for other .NET languages as well(?). I think maybe the best way is to create one answer per topic with a quick and short answer first (close to one-liner if at all possible), then maybe some more information and end with related questions, discussions, blog posts, etc., if there are any. I can then create one post as the accepted answer (to get it on top) with just a "table of contents". Try to keep it short and concise. And don't just link to other questions and blog posts. Try to take the essence of them and then rather link to source (especially since the source could disappear. Also, please try to edit and improve answers instead of created lots of very similar ones. I am not a very good technical writer, but I will at least try to format answers so they look alike, create the table of contents, etc. I will also try to search up some of the related questions here at SO that answers parts of these and maybe pull out the essence of the ones I can manage. But since I am not very stable on this topic, I will try to stay away for the most part :p

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  • multiple stateful iframes per page will overwrite JSESSIONID?

    - by Nikita
    Hello, Looking for someone to either confirm or refute my theory that deploying two iframes pointing to two different stateful pages on the same domain can lead to JSESSIONIDs being overwritten. Here's what I mean: Setup suppose you have two pages that require HttpSession state (session affinity) to function correctly - deployed at http://www.foo.com/page1 and http://www.foo.com/page2 assume www.foo.com is a single host running a Tomcat (6.0.20, fwiw) that uses JSESSIONID for session id's. suppose these pages are turned into two iframe widgets to be embedded on 3rd party sites: http://www.site.com/page1" / (and /page2 respectively) suppose there a 3rd party site that wishes to place both widgets on the same page at http://www.bar.com/foowidgets.html Can the following race condition occur? a new visitor goes to http://www.bar.com/foowidgets.html browser starts loading URLs in foowidgets.html including the two iframe 'src' URLs because browsers open multiple concurrent connections against the same host (afaik up to 6 in chrome/ff case) the browser happens to simultaneously issue requests for http://www.foo.com/page1 and http://www.foo.com/page2 The tomcat @ foo.com receives both requests at about the same time, calls getSession() for the first time (on two different threads) and lazily creates two HttpSessions and, thus, two JSESSIONIDs, with values $Page1 and $Page2. The requests also stuff data into respective sessions (that data will be required to process subsequent requests) assume that the browser first receives response to the page1 request. Browser sets cookie JSESSIONID=$Page1 for HOST www.foo.com next response to the page2 request is received and the browser overwrites cookie JSESSIONID for HOST www.foo.com with $Page2 user clicks on something in 'page1' iframe on foowidgets.html; browser issues 2nd request to http://www.foo.com/page1?action=doSomethingStateful. That request carries JSESSIONID=$Page2 (and not $Page1 - because cookie value was overwritten) when foo.com receives this request it looks up the wrong HttpSession instance (because JSESSIONID key is $Page2 and NOT $Page1). Foobar! Can the above happen? I think so, but would appreciate a confirmation. If the above is clearly possible, what are some solutions given that we'd like to support multiple iframes per page? We don't have a firm need for the iframes to share the same HttpSession, though that would be nice. In the event that the solution will still stipulate a separate HttpSession per iframe, it is - of course - mandatory that iframe 1 does not end up referencing httpSession state for iframe 2 instead of own. off top of my head I can think of: map page1 and page2 to different domains (ops overhead) use URL rewriting and never cookies (messes up analytics) anything else? thanks a lot, -nikita

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  • SubSonic 2.x now supports TVP's - SqlDbType.Structure / DataTables for SQL Server 2008

    - by ElHaix
    For those interested, I have now modified the SubSonic 2.x code to recognize and support DataTable parameter types. You can read more about SQL Server 2008 features here: http://download.microsoft.com/download/4/9/0/4906f81b-eb1a-49c3-bb05-ff3bcbb5d5ae/SQL%20SERVER%202008-RDBMS/T-SQL%20Enhancements%20with%20SQL%20Server%202008%20-%20Praveen%20Srivatsav.pdf What this enhancement will now allow you to do is to create a partial StoredProcedures.cs class, with a method that overrides the stored procedure wrapper method. A bit about good form: My DAL has no direct table access, and my DB only has execute permissions for that user to my sprocs. As such, SubSonic only generates the AllStructs and StoredProcedures classes. The SPROC: ALTER PROCEDURE [dbo].[testInsertToTestTVP] @UserDetails TestTVP READONLY, @Result INT OUT AS BEGIN SET NOCOUNT ON; SET @Result = -1 --SET IDENTITY_INSERT [dbo].[tbl_TestTVP] ON INSERT INTO [dbo].[tbl_TestTVP] ( [GroupInsertID], [FirstName], [LastName] ) SELECT [GroupInsertID], [FirstName], [LastName] FROM @UserDetails IF @@ROWCOUNT > 0 BEGIN SET @Result = 1 SELECT @Result RETURN @Result END --SET IDENTITY_INSERT [dbo].[tbl_TestTVP] OFF END The TVP: CREATE TYPE [dbo].[TestTVP] AS TABLE( [GroupInsertID] [varchar](50) NOT NULL, [FirstName] [varchar](50) NOT NULL, [LastName] [varchar](50) NOT NULL ) GO The the auto gen tool runs, it creates the following erroneous method: /// <summary> /// Creates an object wrapper for the testInsertToTestTVP Procedure /// </summary> public static StoredProcedure TestInsertToTestTVP(string UserDetails, int? Result) { SubSonic.StoredProcedure sp = new SubSonic.StoredProcedure("testInsertToTestTVP", DataService.GetInstance("MyDAL"), "dbo"); sp.Command.AddParameter("@UserDetails", UserDetails, DbType.AnsiString, null, null); sp.Command.AddOutputParameter("@Result", DbType.Int32, 0, 10); return sp; } It sets UserDetails as type string. As it's good form to have two folders for a SubSonic DAL - Custom and Generated, I created a StoredProcedures.cs partial class in Custom that looks like this: /// <summary> /// Creates an object wrapper for the testInsertToTestTVP Procedure /// </summary> public static StoredProcedure TestInsertToTestTVP(DataTable dt, int? Result) { DataSet ds = new DataSet(); SubSonic.StoredProcedure sp = new SubSonic.StoredProcedure("testInsertToTestTVP", DataService.GetInstance("MyDAL"), "dbo"); // TODO: Modify the SubSonic code base in sp.Command.AddParameter to accept // a parameter type of System.Data.SqlDbType.Structured, as it currently only accepts // System.Data.DbType. //sp.Command.AddParameter("@UserDetails", dt, System.Data.SqlDbType.Structured null, null); sp.Command.AddParameter("@UserDetails", dt, SqlDbType.Structured); sp.Command.AddOutputParameter("@Result", DbType.Int32, 0, 10); return sp; } As you can see, the method signature now contains a DataTable, and with my modification to the SubSonic framework, this now works perfectly. I'm wondering if the SubSonic guys can modify the auto-gen to recognize a TVP in a sproc signature, as to avoid having to re-write the warpper? Does SubSonic 3.x support Structured data types? Also, I'm sure many will be interested in using this code, so where can I upload the new code? Thanks.

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  • Building the WAR with m2eclipse in combination with WTP (handling webResources)

    - by waxwing
    I have a situation where I have a web application that is built using maven (i.e., maven-war-plugin). For each code modification, we have had to manually launch maven and restart the application server. Now, to reduce build cycle overhead, I want to use WTP to publish the webapp. Now, we have resource processing with Maven, and there are some additional Maven tasks defined in our POM when building the webapp. Therefore m2eclipse seems like a natural solution. I have gotten far enough that the Maven builder is running these tasks and filtering resources correctly. However, when I choose "Run on Server", the WAR file does not look like it would if I built it in Maven. I am guessing that this is because WTP actually builds the WAR, and not the m2eclipse builder. So even though we have configured the maven-war-plugin in our POM, those settings are not used. Below is a snippet with our maven-war-plugin configuration. What is configured under "webResources" is not picked up, it appears: <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>2.1-alpha-2</version> <configuration> <outputDirectory>${project.build.directory}</outputDirectory> <workDirectory>${project.build.directory}/work</workDirectory> <webappDirectory>${project.build.webappDirectory}</webappDirectory> <cacheFile>${project.build.webappDirectory}/webapp-cache.xml</cacheFile> <filteringDeploymentDescriptors>true</filteringDeploymentDescriptors> <nonFilteredFileExtensions> <nonFilteredFileExtension>pdf</nonFilteredFileExtension> <nonFilteredFileExtension>png</nonFilteredFileExtension> <nonFilteredFileExtension>gif</nonFilteredFileExtension> <nonFilteredFileExtension>jsp</nonFilteredFileExtension> </nonFilteredFileExtensions> <webResources> <!-- Add generated WSDL:s and XSD:s for the web service api. --> <resource> <directory>${project.build.directory}/jaxws/wsgen/wsdl</directory> <targetPath>WEB-INF/wsdl</targetPath> <filtering>false</filtering> <includes> <include>**/*</include> </includes> </resource> </webResources> </configuration> Do I need to reconfigure these resources to be handled elsewhere, or is there a better solution?

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  • debugging JBoss 100% CPU usage

    - by NateS
    Originally posted on Server Fault, where it was suggested this question might better asked here. We are using JBoss to run two of our WARs. One is our web app, the other is our web service. The web app accesses a database on another machine and makes requests to the web service. The web service makes JMS requests to other machines, aggregates the data, and returns it. At our biggest client, about once a month the JBoss Java process takes 100% of all CPUs. The machine running JBoss has 8 CPUs. Our web app is still accessible during this time, however pages take about 3 minutes to load. Restarting JBoss restores everything to normal. The database machine and all the other machines are fine, only the machine running JBoss is affected. Memory usage is normal. Network utilization is normal. There are no suspect error messages in the JBoss logs. I have set up a test environment as close as possible to the client's production environment and I've done load testing with as much as 2x the number of concurrent users. I have not gotten my test environment to replicate the problem. Where do we go from here? How can we narrow down the problem? Currently the only plan we have is to wait until the problem occurs in production on its own, then do some debugging to determine the cause. So far people have just restarted JBoss when the problem occurred to minimize down time. Next time it happens they will get a developer to take a look. The question is, next time it happens, what can be done to determine the cause? We could setup a separate JBoss instance on the same box and install the web app separately from the web service. This way when the problem next occurs we will know which WAR has the problem (assuming it is our code). This doesn't narrow it down much though. Should I enable JMX remote? This way the next time the problem occurs I can connect with VisualVM and see which threads are taking the CPU and what the hell they are doing. However, is there a significant down side to enabling JMX remote in a production environment? Is there another way to see what threads are eating the CPU and to get a stacktrace to see what they are doing? Any other ideas? Thanks!

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  • LINQ InsertOnSubmit Required Fields needed for debugging

    - by Derek Hunziker
    Hi All, I've been using the ADO.NET Strogly-Typed DataSet model for about 2 years now for handling CRUD and stored procedure executions. This past year I built my first MVC app and I really enjoyed the ease and flexibility of LINQ. Perhaps the biggest selling point for me was that with LINQ I didn't have to create "Insert" stored procedures that would return the SCOPE_IDENTITY anymore (The auto-generated insert statements in the DataSet model were not capable of this without modification). Currently, I'm using LINQ with ASP.NET 3.5 WebForms. My inserts are looking like this: ProductsDataContext dc = new ProductsDataContext(); product p = new product { Title = "New Product", Price = 59.99, Archived = false }; dc.products.InsertOnSubmit(p); dc.SubmitChanges(); int productId = p.Id; So, this product example is pretty basic, right, and in the future, I'll probably be adding more fields to the database such as "InStock", "Quantity", etc... The way I understand it, I will need to add those fields to the database table and then delete and re-add the tables to the LINQ to SQL Class design view in order to refresh the DataContext. Does that sound right? The problem is that any new fields that are non-null are NOT caught by the ASP.NET build processes. For example, if I added a non-null field of "Quantity" to the database, the code above would still build. In the DataSet model, the stored procedure method would accept a certain amount of parameters and would warn me that my Insert would fail if I didn't include a quantity value. The same goes for LINQ stored procedure methods, however, to my knowledge, LINQ doesn't offer a way to auto generate the insert statements and that means I'm back to where I started. The bottom line is if I used insert statements like the one above and I add a non-null field to my database, it would break my app in about 10-20 places and there would be no way for me to detect it. Is my only option to do a solution-side search for the keyword "products.InsertOnSubmit" and make sure the new field is getting assigned? Is there a better way? Thanks!

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  • Is this (Lock-Free) Queue Implementation Thread-Safe?

    - by Hosam Aly
    I am trying to create a lock-free queue implementation in Java, mainly for personal learning. The queue should be a general one, allowing any number of readers and/or writers concurrently. Would you please review it, and suggest any improvements/issues you find? Thank you. import java.util.concurrent.atomic.AtomicReference; public class LockFreeQueue<T> { private static class Node<E> { E value; volatile Node<E> next; Node(E value) { this.value = value; } } private AtomicReference<Node<T>> head, tail; public LockFreeQueue() { // have both head and tail point to a dummy node Node<T> dummyNode = new Node<T>(null); head = new AtomicReference<Node<T>>(dummyNode); tail = new AtomicReference<Node<T>>(dummyNode); } /** * Puts an object at the end of the queue. */ public void putObject(T value) { Node<T> newNode = new Node<T>(value); Node<T> prevTailNode = tail.getAndSet(newNode); prevTailNode.next = newNode; } /** * Gets an object from the beginning of the queue. The object is removed * from the queue. If there are no objects in the queue, returns null. */ public T getObject() { Node<T> headNode, valueNode; // move head node to the next node using atomic semantics // as long as next node is not null do { headNode = head.get(); valueNode = headNode.next; // try until the whole loop executes pseudo-atomically // (i.e. unaffected by modifications done by other threads) } while (valueNode != null && !head.compareAndSet(headNode, valueNode)); T value = (valueNode != null ? valueNode.value : null); // release the value pointed to by head, keeping the head node dummy if (valueNode != null) valueNode.value = null; return value; }

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  • Why touching "d_name" makes calls to readdir() fail?

    - by Sarah Mani
    Hi, I'm trying to write a little helper for Windows which eventually will accept a file extension as an argument and return the number of files of that kind in the current directory. To do so, I'm reading the file entries in the directories and after getting the extension I'd like to convert it to lowercase to compare it with the yet-to-add specified argument. When converting the extension to lowercase I found that touching even a duplicate string of the d_name variable will cause a strange behaviour, like no more calls to readdir are called. Here is the code I'm using right now (the commented code is preliminary) and outputs for a given directory: #include <ctype.h> #include <dirent.h> #include <stdio.h> #include <string.h> char * strrch(char *string, size_t elements, char character) { char *reverse = string + elements; while (--reverse != string) if (*reverse == character) return reverse; return NULL; } void test(char *string) { // Even being a duplicate will make it fail: char *str = strdup(string); printf("Strings: %s %s\n", string, str); *str = 'a'; printf("Strings: %s %s\n", string, str); //unsigned short int i = 0; //for (; str[i] != '\0', str++; i++) // str[i] = tolower((unsigned char) str[i]); //puts(str); } int main(int argc, char **argv) { DIR *directory; struct dirent *element; if (directory = opendir(".")) { while (element = readdir(directory)) test(strrch(element->d_name, element->d_namlen, '.')); closedir(directory); puts(NULL); } else puts("Couldn't open the directory.\n"); } Output without modifying the duplicate (modification and the second printf call commented): Strings: (null) (null) Strings: . . Strings: .exe .exe Strings: .pdf .pdf Strings: .c .c Strings: .ini .ini Strings: .pdf .pdf Strings: .pdf .pdf Strings: .pdf .pdf Strings: .flac .flac Strings: .FLAC .FLAC Strings: .lnk .lnk Strings: .URL .URL Output of the same directory (with the code above, with the 2 printfs): Strings: (null) (null) Is there anything wrong? Is it a compiler issue? I'm using GCC 4.4.3 in Windows (MinGW) right now. Thank you very much for your help. By the way, is there any other way to work with files and directories in a Windows environment not using the POSIX functions?

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  • Correlated SQL Join Query from multiple tables

    - by SooDesuNe
    I have two tables like the ones below. I need to find what exchangeRate was in effect at the dateOfPurchase. I've tried some correlated sub queries, but I'm having difficulty getting the correlated record to be used in the sub queries. I expect a solution will need to follow this basic outline: SELECT only the exchangeRates for the applicable countryCode From 1. SELECT the newest exchangeRate less than the dateOfPurchase Fill in the query table with all the fields from 2. and the purchasesTable. My Tables: purchasesTable: > dateOfPurchase | costOfPurchase | countryOfPurchase > 29-March-2010 | 20.00 | EUR > 29-March-2010 | 3000 | JPN > 30-March-2010 | 50.00 | EUR > 30-March-2010 | 3000 | JPN > 30-March-2010 | 2000 | JPN > 31-March-2010 | 100.00 | EUR > 31-March-2010 | 125.00 | EUR > 31-March-2010 | 2000 | JPN > 31-March-2010 | 2400 | JPN costOfPurchase is in whatever the local currency is for a given countryCode exchangeRateTable > effectiveDate | countryCode | exchangeRate > 29-March-2010 | JPN | 90 > 29-March-2010 | EUR | 1.75 > 30-March-2010 | JPN | 92 > 31-March-2010 | JPN | 91 The results of the query that I'm looking for: > dateOfPurchase | costOfPurchase | countryOfPurchase | exchangeRate > 29-March-2010 | 20.00 | EUR | 1.75 > 29-March-2010 | 3000 | JPN | 90 > 30-March-2010 | 50.00 | EUR | 1.75 > 30-March-2010 | 3000 | JPN | 92 > 30-March-2010 | 2000 | JPN | 92 > 31-March-2010 | 100.00 | EUR | 1.75 > 31-March-2010 | 125.00 | EUR | 1.75 > 31-March-2010 | 2000 | JPN | 91 > 31-March-2010 | 2400 | JPN | 91 So for example in the results, the exchange rate, in effect for EUR on 31-March was 1.75. I'm using Access, but a MySQL answer would be fine too. UPDATE: Modification to Allan's answer: SELECT dateOfPurchase, costOfPurchase, countryOfPurchase, exchangeRate FROM purchasesTable p LEFT OUTER JOIN (SELECT e1.exchangeRate, e1.countryCode, e1.effectiveDate, min(e2.effectiveDate) AS enddate FROM exchangeRateTable e1 LEFT OUTER JOIN exchangeRateTable e2 ON e1.effectiveDate < e2.effectiveDate AND e1.countryCode = e2.countryCode GROUP BY e1.exchangeRate, e1.countryCode, e1.effectiveDate) e ON p.dateOfPurchase >= e.effectiveDate AND (p.dateOfPurchase < e.enddate OR e.enddate is null) AND p.countryOfPurchase = e.countryCode I had to make a couple small changes.

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  • Tomcat JNDI Connection Pool docs - Random Connection Closed Exceptions

    - by Andy Faibishenko
    I found this in the Tomcat documentation here What I don't understand is why they close all the JDBC objects twice - once in the try{} block and once in the finally{} block. Why not just close them once in the finally{} clause? This is the relevant docs: Random Connection Closed Exceptions These can occur when one request gets a db connection from the connection pool and closes it twice. When using a connection pool, closing the connection just returns it to the pool for reuse by another request, it doesn't close the connection. And Tomcat uses multiple threads to handle concurrent requests. Here is an example of the sequence of events which could cause this error in Tomcat: Request 1 running in Thread 1 gets a db connection. Request 1 closes the db connection. The JVM switches the running thread to Thread 2 Request 2 running in Thread 2 gets a db connection (the same db connection just closed by Request 1). The JVM switches the running thread back to Thread 1 Request 1 closes the db connection a second time in a finally block. The JVM switches the running thread back to Thread 2 Request 2 Thread 2 tries to use the db connection but fails because Request 1 closed it. Here is an example of properly written code to use a db connection obtained from a connection pool: Connection conn = null; Statement stmt = null; // Or PreparedStatement if needed ResultSet rs = null; try { conn = ... get connection from connection pool ... stmt = conn.createStatement("select ..."); rs = stmt.executeQuery(); ... iterate through the result set ... rs.close(); rs = null; stmt.close(); stmt = null; conn.close(); // Return to connection pool conn = null; // Make sure we don't close it twice } catch (SQLException e) { ... deal with errors ... } finally { // Always make sure result sets and statements are closed, // and the connection is returned to the pool if (rs != null) { try { rs.close(); } catch (SQLException e) { ; } rs = null; } if (stmt != null) { try { stmt.close(); } catch (SQLException e) { ; } stmt = null; } if (conn != null) { try { conn.close(); } catch (SQLException e) { ; } conn = null; } }

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  • How can a test script inform R CMD check that it should emit a custom message?

    - by mariotomo
    I'm writing a R package (delftfews) here at office. we are using svUnit for unit testing. our process for describing new functionality: we define new unit tests, initially marked as DEACTIVATED; one block of tests at a time we activate them and implement the function described by the tests. almost all the time we have a small amount of DEACTIVATED tests, relative to functions that might be dropped or will be implemented. my problem/question is: can I alter the doSvUnit.R so that R CMD check pkg emits a NOTE (i.e. a custom message "NOTE" instead of "OK") in case there are DEACTIVATED tests? as of now, we see only that the active tests don't give error: . . * checking for unstated dependencies in tests ... OK * checking tests ... Running ‘doSvUnit.R’ OK * checking PDF version of manual ... OK which is all right if all tests succeed, but less all right if there are skipped tests and definitely wrong if there are failing tests. In this case, I'd actually like to see a NOTE or a WARNING like the following: . . * checking for unstated dependencies in tests ... OK * checking tests ... Running ‘doSvUnit.R’ NOTE 6 test(s) were skipped. WARNING 1 test(s) are failing. * checking PDF version of manual ... OK As of now, we have to open the doSvUnit.Rout to check the real test results. I contacted two of the maintainers at r-forge and CRAN and they pointed me to the sources of R, in particular the testing.R script. if I understand it correctly, to answer this question we need patching the tools package: scripts in the tests directory are called using a system call, output (stdout and stderr) go to one single file, there are two possible outcomes: ok or not ok, so I opened a change request on R, proposing something like bit-coding the return status, bit-0 for ERROR (as it is now), bit-1 for WARNING, bit-2 for NOTE. with my modification, it would be easy producing this output: . . * checking for unstated dependencies in tests ... OK * checking tests ... Running ‘doSvUnit.R’ NOTE - please check doSvUnit.Rout. WARNING - please check doSvUnit.Rout. * checking PDF version of manual ... OK Brian Ripley replied "There are however several packages with properly written unit tests that do signal as required. Please do take this discussion elsewhere: R-bugs is not the place to ask questions." and closed the change request. anybody has hints?

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  • iPhone: Speeding up a search that's polling 17,000 Core Data objects

    - by randombits
    I have a class that conforms to UISearchDisplayDelegate and contains a UISearchBar. This view is responsible for allowing the user to poll a store of about 17,000 objects that are currently managed by Core Data. Everytime the user types in a character, I created an instance of a SearchOperation (subclasses NSOperation) that queries Core Data to find results that might match the search. The code in the search controller looks something like: - (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope { // Update the filtered array based on the search text and scope in a secondary thread if ([searchText length] < 3) { [filteredList removeAllObjects]; // First clear the filtered array. [self setFilteredList:NULL]; [self.tableView reloadData]; return; } NSDictionary *searchdict = [NSDictionary dictionaryWithObjectsAndKeys:scope, @"scope", searchText, @"searchText", nil]; [aSearchQueue cancelAllOperations]; SearchOperation *searchOp = [[SearchOperation alloc] initWithDelegate:self dataDict:searchdict]; [aSearchQueue addOperation:searchOp]; } And my search is rather straight forward. SearchOperation is a subclass of NSOperation. I overwrote the main method with the following code: - (void)main { if ([self isCancelled]) { return; } NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"MyEntity" inManagedObjectContext:managedObjectContext]; NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; [fetchRequest setEntity:entity]; NSPredicate *predicate = NULL; predicate = [NSPredicate predicateWithFormat:@"(someattr contains[cd] %@)", searchText]; [fetchRequest setPredicate:predicate]; NSError *error = NULL; NSArray *fetchResults = [managedObjectContext executeFetchRequest:fetchRequest error:&error]; [fetchRequest release]; if (self.delegate != nil) [self.delegate didFinishSearching:fetchResults]; [pool drain]; } This code works, but it has several issues. It's slow. Even though I have the search happening in a separate thread other than the UI thread, querying 17,000 objects is clearly not optimal. If I'm not careful, crashes can happen. I set the max concurrent searches in my NSOperationQueue to 1 to avoid this. What else can I do to make this search faster? I think preloading all 17,000 objects into memory might be risky. There has to be a smarter way to conduct this search to give results back to the user faster.

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  • Core-Data + AFNetworking + UI Updating (Responsiveness)

    - by Mustafa
    Here's the scenario: I'm writing a DownloadManager, that allows the user to download, pause, cancel, download all, and pause all. The DownloadManager is a singleton, and uses AFNetworking to download files. It has it's own private managed object context, so that user can freely use other parts of the application (by adding, editing, deleting) core-data objects. I have a core-data entity DownloadInfo that stores the download information i.e. fileURL, fileSize, bytesRead, etc. The DownloadManager updates the download progress in DownloadInfo (one for each file). I have a DownloadManagerViewController which uses NSFetchedResultsController to show the download status to the user. This download view controller is using the main managed object context. Now let's say that I have 20 files in the download queue. And let's say that only 3 concurrent downloads are allowed. The download manager should download the file, and show the download progress. Problem: The DownloadInfo objects are being updated by the DownloadManager at a very high rate. The DownloadManagerViewController (responsible for showing the download progress) is updating the list using NSFetchedResultsControllerDelegate methods. The result is that a lot is happening in the main queue and application has very poor responsiveness. How can I fix this? How can I make the application responsive, while showing the download progress? I don't know how else to communicate that the download status between DownloadManager and DownloadManagerViewController. Is there another/ a better way to do this? I don't want to use main managed object context in my DownloadManager, for reasons mentioned above. Note, that the DownloadManager is using AFNetworking which is handling the requests asynchronously, but eventually the DownloadInfo objects are updated in the main thread (as a result of the callback methods). Maybe there's a way to handle the downloads and status update operations in a background thread? but how? How will I communicate between the main thread and the background thread i.e. how will I tell the background thread to queue another file for download? Thanks.

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  • Using VCL for the web (intraweb) as a trick for adding web interface to a legacy non-tiered (2 tiers

    - by user193655
    My team is maintaining a huge Client Server win32 Delphi application. It is a client/server application (Thick client) that uses DevArt (SDAC) components to connect to SQL Server. The business logic is often "trapped" in Component's event handlers, anyway with some degree of refactoring it is doable to move the business logic in common units (a big part of this work has already been done during refactoring... Maintaing legacy applications someone else wrote is very frustrating, but this is a very common job). Now there is the request of a web interface, I have several options of course, in this question i want to focus on the VCL for the web (intraweb) option. The idea is to use the common code (the same pas files) for both the client/server application and the web application. I heard of many people that moved legacy apps from delphi to intraweb, but here I am trying to keep the Thick client too. The idea is to use common code, may be with some compiler directives to write specific code: {$IFDEF CLIENTSERVER} {here goes the thick client specific code} {$ELSE} {here goes the Intraweb specific code} {$ENDIF} Then another problem is the "migration plan", let's say I have 300 features and on the first release I will have only 50 of them available in the web application. How to keep track of it? I was thinking of (ab)using Delphi interfaces to handle this. For example for the User Authentication I could move all the related code in a procedure and declare an interface like: type IUserAuthentication= interface['{0D57624C-CDDE-458B-A36C-436AE465B477}'] procedure UserAuthentication; end; In this way as I implement the IUserAuthentication interface in both the applications (Thick Client and Intraweb) I know that That feature has been "ported" to the web. Anyway I don't know if this approach makes sense. I made a prototype to simulate the whole process. It works for a "Hello world" application, but I wonder if it makes sense on a large application or this Interface idea is only counter-productive and can backfire. My question is: does this approach make sense? (the Interface idea is just an extra idea, it is not so important as the common code part described above) Is it a viable option? I understand it depends a lot of the kind of application, anyway to be generic my one is in the CRM/Accounting domain, and the number of concurrent users on a single installation is typically less than 20 with peaks of 50. EXTRA COMMENT (UPDATE): I ask this question because since I don't have a n-tier application I see Intraweb as the unique option for having a web application that has common code with the thick client. Developing webservices from the Delphi code makes no sense in my specific case, so the alternative I have is to write the web interface using ASP.NET (duplicating the business logic), but in this case I cannot take advantage of the common code in an easy way. Yes I could use dlls maybe, but my code is not suitable for that.

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  • Any simple approaches for managing customer data change requests for global reference files?

    - by Kelly Duke
    For the first time, I am developing in an environment in which there is a central repository for a number of different industry standard reference data tables and many different customers who need to select records from these industry standard reference data tables to fill in foreign key information for their customer specific records. Because these industry standard reference files are utilized by all customers, I want to reserve Create/Update/Delete access to these records for global product administrators. However, I would like to implement a (semi-)automated interface by which specific customers could request record additions, deletions or modifications to any of the industry standard reference files that are shared among all customers. I know I need something like a "data change request" table specifying: user id, user request datetime, request type (insert, modify, delete), a user entered text explanation of the change request, the user request's current status (pending, declined, completed), admin resolution datetime, admin id, an admin entered text description of the resolution, etc. What I can't figure out is how to elegantly handle the fact that these data change requests could apply to dozens of different tables with differing table column definitions. I would like to give the customer users making these data change requests a convenient way to enter their proposed record additions/modifications directly into CRUD screens that look very much like the reference table CRUD screens they don't have write/delete permissions for (with an additional text explanation and perhaps request priority field). I would also like to give the global admins a tool that allows them to view all the outstanding data change requests for the users they oversee sorted by date requested or user/date requested. Upon selecting a data change request record off the list, the admin would be directed to another CRUD screen that would be populated with the fields the customer users requested for the new/modified industry standard reference table record along with customer's text explanation, the request status and the text resolution explanation field. At this point the admin could accept/edit/reject the requested change and if accepted the affected industry standard reference file would be automatically updated with the appropriate fields and the data change request record's status, text resolution explanation and resolution datetime would all also be appropriately updated. However, I want to keep the actual production reference tables as simple as possible and free from these extraneous and typically null customer change request fields. I'd also like the data change request file to aggregate all data change requests across all the reference tables yet somehow "point to" the specific reference table and primary key in question for modification & deletion requests or the specific reference table and associated customer user entered field values in question for record creation requests. Does anybody have any ideas of how to design something like this effectively? Is there a cleaner, simpler way I am missing? Thank you so much for reading.

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  • Running same powershell script multiple asynchronous times with separate runspace

    - by teqnomad
    Hi, I have a powershell script which is called by a batch script which is called by Trap Receiver (which also passes environment variables) (running on windows 2008). The traps are flushed out at times in sets of 2-4 trap events, and the batch script will echo the trap details for each message to a logfile, but the powershell script on the next line of the batch script will only appear to process the first trap message (the powershell script writes to the same logfile). My interpetation is that the defaultrunspace is common to all iterations of the script running and this is why the others appear to be ignored. I've tried adding "-sta" when I invoke the powershell script using "powershell.exe -command", but this didn't help. I've researched and found a method using C# but I don't know this language, and busy enough learning powershell, so hoping to find a more direct solution especially as interleaving a "wrapper" between batch and powershell will involve passing the environment variables. http://www.codeproject.com/KB/threads/AsyncPowerShell.aspx I've hunted through stackoverflow, and again the only question of similar vein was using C#. Any suggestions welcome. Some script background: The powershell script is actually a modification of a great script found at gregorystrike website - cant post the link as I'm limited to one link but its the one for Lefthand arrays. Lots of mods so it can do multiple targets from one .ini file, taking in the environment variables, and options to run portions of the script interactively with winform. But you can see the gist of the original script. The batch script is pretty basic. The keys things are I'm trying to filter out trap noise using the :~ operator, and I tried -sta option to see if this would compartmentalise the powershell script. set debug=off set CMD_LINE_ARGS="%*" set LHIPAddress="%2" set VARBIND8="%8" shift shift shift shift shift shift shift set CHASSIS="%9" echo %DATE% %TIME% "Trap Received: %LHIPAddress% %CHASSIS% %VARBIND8%" >> C:\Logs\trap_out.txt set ACTION="%VARBIND8:~39,18%" echo %DATE% %TIME% "Action substring is %ACTION%" 2>&1 >> C:\Logs\trap_out.txt if %ACTION%=="Remote Copy Volume" ( echo Prepostlefthand_env_v2.9 >> C:\Logs\trap_out.txt c:\Windows\System32\WindowsPowerShell\v1.0\PowerShell.exe -sta -executionpolicy unrestricted -command " & 'C:\Scripts\prepostlefthand_env_v2.9.ps1' Backupsettings.ini ALL" 2>&1 >> C:\Logs\trap_out.txt ) ELSE ( echo %DATE% %TIME% Action substring is %ACTION% so exiting" 2>&1 >> C:\Logs\trap.out.txt ) exit

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  • Fairness: Where can it be better handled?

    - by Srinivas Nayak
    Hi, I would like to share one of my practical experience with multiprogramming here. Yesterday I had written a multiprogram. Modifications to sharable resources were put under critical sections protected by P(mutex) and V(mutex) and those critical section code were put in a common library. The library will be used by concurrent applications (of my own). I had three applications that will use the common code from library and do their stuff independently. my library --------- work_on_shared_resource { P(mutex) get_shared_resource work_with_it V(mutex) } --------- my application ----------- application1 { *[ work_on_shared_resource do_something_else_non_ctitical ] } application2 { *[ work_on_shared_resource do_something_else_non_ctitical ] } application3 { *[ work_on_shared_resource ] } *[...] denote a loop. ------------ I had to run the applications on Linux OS. I had a thought in my mind, hanging over years, that, OS shall schedule all the processes running under him with all fairness. In other words, it will give all the processes, their pie of resource-usage equally well. When first two applications were put to work, they run perfectly well without deadlock. But when the third application started running, always the third one got the resources, but since it is not doing anything in its non-critical region, it gets the shared resource more often when other tasks are doing something else. So the other two applications were found almost totally halted. When the third application got terminated forcefully, the previous two applications resumed their work as before. I think, this is a case of starvation, first two applications had to starve. Now how can we ensure fairness? Now I started believing that OS scheduler is innocent and blind. It depends upon who won the race; he got the largest pie of CPU and resource. Shall we attempt to ensure fairness of resource users in the critical-section code in library? Or shall we leave it up to the applications to ensure fairness by being liberal, not greedy? To my knowledge, adding code to ensure fairness to the common library shall be an overwhelming task. On the other hand, believing on the applications will also never ensure 100% fairness. The application which does a very little task after working with shared resources shall win the race where as the application which does heavy processing after their work with shared resources shall always starve. What is the best practice in this case? Where we ensure fairness and how? Sincerely, Srinivas Nayak

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  • working on lists in python

    - by owca
    I'm trying to make a small modification to django lfs project, that will allow me to deactivate products with no stocks. Unfortunatelly I'm just beginning to learn python, so I have big trouble with its syntax. That's what I'm trying to do. I'm using method 'has_variants' which returns true if product has any. Then I'm building a list from variants for this product. Next for every product in this list (I've called it 'set') I check it's stock and set bool variable 'inactive' to true if product has no stocks and to false if there are any. Finally if 'inactive' is false I'm setting self.active to 0. Code fails in line with: set[] = s How to correct it ? def deactivate(self): """If there are no stocks, deactivate the product. Used in last step of checkout. """ if self.has_variants(): for s in self.variants.filter(active=True): set[] = s for var in set: if var.get_stock_amount() == 0: inactive = True else: inactive = False else: if self.get_stock_amount() == 0: inactive = True if inactive: self.active = False return 0 error log : Traceback (most recent call last): File "manage.py", line 11, in <module> execute_manager(settings) File "/home/purplecow/rails/purpledev/site-packages/django/core/management/__i nit__.py", line 362, in execute_manager utility.execute() File "/home/purplecow/rails/purpledev/site-packages/django/core/management/__i nit__.py", line 303, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "/home/purplecow/rails/purpledev/site-packages/django/core/management/bas e.py", line 195, in run_from_argv self.execute(*args, **options.__dict__) File "/home/purplecow/rails/purpledev/site-packages/django/core/management/bas e.py", line 213, in execute translation.activate('en-us') File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/_ _init__.py", line 73, in activate return real_activate(language) File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/_ _init__.py", line 43, in delayed_loader return g['real_%s' % caller](*args, **kwargs) File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/t rans_real.py", line 205, in activate _active[currentThread()] = translation(language) File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/t rans_real.py", line 194, in translation default_translation = _fetch(settings.LANGUAGE_CODE) File "/home/purplecow/rails/purpledev/site-packages/django/utils/translation/t rans_real.py", line 180, in _fetch app = import_module(appname) File "/home/purplecow/rails/purpledev/site-packages/django/utils/importlib.py" , line 35, in import_module __import__(name) File "/home/purplecow/rails/purpledev/lfs/caching/__init__.py", line 1, in <mo dule> from listeners import * File "/home/purplecow/rails/purpledev/lfs/caching/listeners.py", line 10, in < module> from lfs.cart.models import Cart File "/home/purplecow/rails/purpledev/lfs/cart/models.py", line 8, in <module> from lfs.catalog.models import Product File "/home/purplecow/rails/purpledev/lfs/catalog/__init__.py", line 1, in <mo dule> from listeners import * File "/home/purplecow/rails/purpledev/lfs/catalog/listeners.py", line 5, in <m odule> from lfs.catalog.models import PropertyGroup File "/home/purplecow/rails/purpledev/lfs/catalog/models.py", line 589 set[] = s ^ SyntaxError: invalid syntax

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  • C++ Unlocking a std::mutex before calling std::unique_lock wait

    - by Sant Kadog
    I have a multithreaded application (using std::thread) with a manager (class Tree) that executes some piece of code on different subtrees (embedded struct SubTree) in parallel. The basic idea is that each instance of SubTree has a deque that store objects. If the deque is empty, the thread waits until a new element is inserted in the deque or the termination criteria is reached. One subtree can generate objects and push them in the deque of another subtree. For convenience, all my std::mutex, std::locks and std::variable_condition are stored in a struct called "locks". The class Tree creates some threads that run the following method (first attempt) : void Tree::launch(SubTree & st, Locks & locks ) { /* some code */ std::lock_guard<std::mutex> deque_lock(locks.deque_mutex_[st.id_]) ; // lock the access to the deque of subtree st if (st.deque_.empty()) // check that the deque is still empty { // some threads are still running, wait for them to terminate std::unique_lock<std::mutex> wait_lock(locks.restart_mutex_[st.id_]) ; locks.restart_condition_[st.id_].wait(wait_lock) ; } /* some code */ } The problem is that "deque_lock" is still locked while the thread is waiting. Hence no object can be added in the deque of the current thread by a concurrent one. So I turned the lock_guard into a unique_lock and managed the lock/unlock manually : void launch(SubTree & st, Locks & locks ) { /* some code */ std::unique_lock<std::mutex> deque_lock(locks.deque_mutex_[st.id_]) ; // lock the access to the deque of subtree st if (st.deque_.empty()) // check that the deque is still empty { deque_lock.unlock() ; // unlock the access to the deque to enable the other threads to add objects // DATA RACE : nothing must happen to the unprotected deque here !!!!!! // some threads are still running, wait for them to terminate std::unique_lock<std::mutex> wait_lock(locks.restart_mutex_[st.id_]) ; locks.restart_condition_[st.id_].wait(wait_lock) ; } /* some code */ } The problem now, is that there is a data race, and I would like to make sure that the "wait" instruction is performed directly after the "deque_lock.unlock()" one. Would anyone know a way to create such a critical instruction sequence with the standard library ? Thanks in advance.

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  • Accessing different connection strings at runtime in ASP.NET MVC 1

    - by Neil T.
    I'm trying to implement integration testing in my ASP.NET MVC 1.0 solution. The technologies in use are LINQ-to-SQL, NUnit and WatiN. I recently discovered a pattern that will allow me to create a testing version of the database on the fly without modifying the development version of the database. I needed this behavior in order to run my user interface tests in WatiN that may modify the database. The plan is to modify the connection string in the Web.config file, and pass that new connection string to the DataContext constructor. This way, I don't have to add routes or modify my URLs in order to perform the integration testing. I've set up the project so that the test setup can modify the connection string to point to the test database when the tests are running. The connection string is stored in web.config. The problem I'm having is that when I try to run the tests, I get a NullReferenceException when trying to access the HTTPContext. From everything that I have read so far, the HTTPContext is only available within the context of a controller. Here is the code for the property that is supposed to give me the reference to the Web.config file: private System.Configuration.Configuration WebConfig { get { ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap(); // NullReferenceException occurs on this line. fileMap.ExeConfigFilename = HttpContext.Current.Server.MapPath("~\\web.config"); System.Configuration.Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None); return config; } } Is there something that I am missing in order to make this work? Is there a better way to accomplish what I'm trying to achieve? UPDATE: I decided to abandon the modification of Web.config in lieu of a "request-scoped DataContext" pattern that I found here. From the looks of it, I believe it should give me the results I'm looking for. However, during the TextFixtureSetUp, I try to create a new copy of the database for testing purposes, and it fails silently. When I get to the tests, the repository still uses the production database connection string to load data.

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  • WTF is wtf? (in WebKit code base)

    - by Motti
    I downloaded Chromium's code base and ran across the WTF namespace. namespace WTF { /* * C++'s idea of a reinterpret_cast lacks sufficient cojones. */ template<typename TO, typename FROM> TO bitwise_cast(FROM in) { COMPILE_ASSERT(sizeof(TO) == sizeof(FROM), WTF_wtf_reinterpret_cast_sizeof_types_is_equal); union { FROM from; TO to; } u; u.from = in; return u.to; } } // namespace WTF Does this mean what I think it means? Could be so, the bitwise_cast implementation specified here will not compile if either TO or FROM is not a POD and is not (AFAIK) more powerful than C++ built in reinterpret_cast. The only point of light I see here is the nobody seems to be using bitwise_cast in the Chromium project. I see there's some legalese so I'll put in the little letters to keep out of trouble. /* * Copyright (C) 2008 Apple Inc. All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */

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  • Available Coroutine Libraries in Java

    - by JUST MY correct OPINION
    I would like to do some stuff in Java that would be clearer if written using concurrent routines, but for which full-on threads are serious overkill. The answer, of course, is the use of coroutines, but there doesn't appear to be any coroutine support in the standard Java libraries and a quick Google on it brings up tantalising hints here or there, but nothing substantial. Here's what I've found so far: JSIM has a coroutine class, but it looks pretty heavyweight and conflates, seemingly, with threads at points. The point of this is to reduce the complexity of full-on threading, not to add to it. Further I'm not sure that the class can be extracted from the library and used independently. Xalan has a coroutine set class that does coroutine-like stuff, but again it's dubious if this can be meaningfully extracted from the overall library. It also looks like it's implemented as a tightly-controlled form of thread pool, not as actual coroutines. There's a Google Code project which looks like what I'm after, but if anything it looks more heavyweight than using threads would be. I'm basically nervous of something that requires software to dynamically change the JVM bytecode at runtime to do its work. This looks like overkill and like something that will cause more problems than coroutines would solve. Further it looks like it doesn't implement the whole coroutine concept. By my glance-over it gives a yield feature that just returns to the invoker. Proper coroutines allow yields to transfer control to any known coroutine directly. Basically this library, heavyweight and scary as it is, only gives you support for iterators, not fully-general coroutines. The promisingly-named Coroutine for Java fails because it's a platform-specific (obviously using JNI) solution. And that's about all I've found. I know about the native JVM support for coroutines in the Da Vinci Machine and I also know about the JNI continuations trick for doing this. These are not really good solutions for me, however, as I would not necessarily have control over which VM or platform my code would run on. (Indeed any bytecode manipulation system would suffer similar problems -- it would be best were this pure Java if possible. Runtime bytecode manipulation would restrict me from using this on Android, for example.) So does anybody have any pointers? Is this even possible? If not, will it be possible in Java 7? Edited to add: Just to ensure that confusion is contained, this is a related question to my other one, but not the same. This one is looking for an existing implementation in a bid to avoid reinventing the wheel unnecessarily. The other one is a question relating to how one would go about implementing coroutines in Java should this question prove unanswerable. The intent is to keep different questions on different threads.

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