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  • Avoiding secondary selects or joins with Hibernate Criteria or HQL query

    - by Ben Benson
    I am having trouble optimizing Hibernate queries to avoid performing joins or secondary selects. When a Hibernate query is performed (criteria or hql), such as the following: return getSession().createQuery(("from GiftCard as card where card.recipientNotificationRequested=1").list(); ... and the where clause examines properties that do not require any joins with other tables... but Hibernate still performs a full join with other tables (or secondary selects depending on how I set the fetchMode). The object in question (GiftCard) has a couple ManyToOne associations that I would prefer to be lazily loaded in this case (but not necessarily all cases). I want a solution that I can control what is lazily loaded when I perform the query. Here's what the GiftCard Entity looks like: @Entity @Table(name = "giftCards") public class GiftCard implements Serializable { private static final long serialVersionUID = 1L; private String id_; private User buyer_; private boolean isRecipientNotificationRequested_; @Id public String getId() { return this.id_; } public void setId(String id) { this.id_ = id; } @ManyToOne @JoinColumn(name = "buyerUserId") @NotFound(action = NotFoundAction.IGNORE) public User getBuyer() { return this.buyer_; } public void setBuyer(User buyer) { this.buyer_ = buyer; } @Column(name="isRecipientNotificationRequested", nullable=false, columnDefinition="tinyint") public boolean isRecipientNotificationRequested() { return this.isRecipientNotificationRequested_; } public void setRecipientNotificationRequested(boolean isRecipientNotificationRequested) { this.isRecipientNotificationRequested_ = isRecipientNotificationRequested; } }

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  • Long running transactions with Spring and Hibernate?

    - by jimbokun
    The underlying problem I want to solve is running a task that generates several temporary tables in MySQL, which need to stay around long enough to fetch results from Java after they are created. Because of the size of the data involved, the task must be completed in batches. Each batch is a call to a stored procedure called through JDBC. The entire process can take half an hour or more for a large data set. To ensure access to the temporary tables, I run the entire task, start to finish, in a single Spring transaction with a TransactionCallbackWithoutResult. Otherwise, I could get a different connection that does not have access to the temporary tables (this would happen occasionally before I wrapped everything in a transaction). This worked fine in my development environment. However, in production I got the following exception: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction This happened when a different task tried to access some of the same tables during the execution of my long running transaction. What confuses me is that the long running transaction only inserts or updates into temporary tables. All access to non-temporary tables are selects only. From what documentation I can find, the default Spring transaction isolation level should not cause MySQL to block in this case. So my first question, is this the right approach? Can I ensure that I repeatedly get the same connection through a Hibernate template without a long running transaction? If the long running transaction approach is the correct one, what should I check in terms of isolation levels? Is my understanding correct that the default isolation level in Spring/MySQL transactions should not lock tables that are only accessed through selects? What can I do to debug which tables are causing the conflict, and prevent those tables from being locked by the transaction?

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  • Database Error Handling: What if You have to Call Outside service and the Transaction Fails?

    - by Ngu Soon Hui
    We all know that we can always wrap our database call in transaction ( with or without a proper ORM), in a form like this: $con = Propel::getConnection(EventPeer::DATABASE_NAME); try { $con->begin(); // do your update, save, delete or whatever here. $con->commit(); } catch (PropelException $e) { $con->rollback(); throw $e; } This way would guarantee that if the transaction fails, the database is restored to the correct status. But the problem is that let's say when I do a transaction, in addition to that transaction, I need to update another database ( an example would be when I update an entry in a column in databaseA, another entry in a column in databaseB must be updated). How to handle this case? Let's say, this is my code, I have three databases that need to be updated ( dbA, dbB, dbc): $con = Propel::getConnection("dbA"); try { $con->begin(); // update to dbA // update to dbB //update to dbc $con->commit(); } catch (PropelException $e) { $con->rollback(); throw $e; } If dbc fails, I can rollback the dbA but I can't rollback dbb. I think this problem should be database independent. And since I am using ORM, this should be ORM independent as well. Update: Some of the database transactions are wrapped in ORM, some are using naked PDO, oledb ( or whatever bare minimum language provided database calls). So my solution has to take care this. Any idea?

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  • Cocoa Services Programming - How to identify whether the selected item is a folder or file wih NSFi

    - by rockybalboa
    Hi , I have some queries regarding Services menu validation . I would like to enable different services provided by my app based on whether a file or folder is selected in the Finder. I have set NSFilenamesPboardType as the send type for the services . I have gone through the - (id)validRequestorForSendType:(NSString *)sendType returnType:(NSString *)returnType method but my issue is that the validation there seems to be done based on the sendType and return type. In my case , the selected file and folder pasteboard type is the same and I cannot determine whether the selected item in the Finder is a file or folder during the validation process ( This is before the actual service gets invoked i.e when the services menu is being shown to the user ) ? So my question is that is there any way I can get some info about the selected item in the Finder and validate the different service menus offered by my application based on some info regarding the item rather than the basic validation of the send and return types ? I am not able to find out any manner to do so but "Folder Actions" service in Snow Leopard gets enabled only for folders so it can be done. I did a /System/Library/CoreServices/pbs -dump_pboard and it is using a NSFilenamePBoardType also yet manages to activate only for folders. Thanks in advace for any help .

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  • Why am I getting "(304) Not Modified" error on some links when using HttpWebRequest?

    - by Greg
    Hi, Any ideas why on some links that I try to access using HttpWebRequest I am getting "The remote server returned an error: (304) Not Modified." in the code? The code I'm using is from Jeff's post here. Note the concept of the code is a simple proxy server, so I'm pointing my browser at this locally running piece of code, which gets my browsers request, and then proxies it on by creating a new HttpWebRequest, as you'll see in the code. It works great for most sites/links, but for some this error comes up. You will see one key bit in the code is where it seems to copy the http header settings from the browser request to it's request out to the site, and it copies in the header attributes. Not sure if the issue is something to do with how it mimics this aspect of the request and then what happens as the result comes back? case "If-Modified-Since": request.IfModifiedSince = DateTime.Parse(listenerContext.Request.Headers[key]); break; I get the issue for example from http://en.wikipedia.org/wiki/Main_Page thanks

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  • How to have a where clause on an insert or an update in Linq to Sql?

    - by Kelsey
    I am trying to convert the following stored proc to a LinqToSql call (this is a simplied version of the SQL): INSERT INTO [MyTable] ([Name], [Value]) SELECT @name, @value WHERE NOT EXISTS(SELECT [Value] FROM [MyTable] WHERE [Value] = @value) The DB does not have a constraint on the field that is getting checked for so in this specific case the check needs to be made manually. Also there are many items constantly being inserted as well so I need to make sure that when this specific insert happens there is no dupe of the value field. My first hunch is to do the following: using (TransactionScope scope = new TransactionScope()) { if (Context.MyTables.SingleOrDefault(t => t.Value == in.Value) != null) { MyLinqModels.MyTable t = new MyLinqModels.MyTable() { Name = in.Name, Value = in.Value }; // Do some stuff in the transaction scope.Complete(); } } This is the first time I have really run into this scenario so I want to make sure I am going about it the right way. Does this seem correct or can anyone suggest a better way of going about it without having two seperate calls? Edit: I am running into a similar issue with an update: UPDATE [AnotherTable] SET [Code] = @code WHERE [ID] = @id AND [Code] IS NULL How would I do the same check with Linqtosql? I assume I need to do a get and then set all the values and submit but what if someone updates [Code] to something other than null from the time I do the get to when the update executes? Same problem as the insert...

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  • How do you fix issues with the debugger for the Android plug-in for Eclipse not attaching?

    - by user279112
    I have been trying to program something for the Android mobile phone, using Eclipse and the Android plug-in for that IDE, and my debugger used to attach just fine. But then it has suddenly started having consistent issues attaching. I just get that message about how the process is waiting for the debugger attach, and then it just won't. What determines whether the attachment glitches so seems to have something to do with what the code is that I'm trying to debug, as it seems to be drastically more of an issue with some versions of my code than with others (on the same app). How do I fix this? Now before you answer, please understand that I have researched this issue already. I have found a couple of solutions that have worked with other people, but which do not work for me. One of which is setting the debuggable property in the main manifest file as true, and the other is going into Dev Tools and into some settings menu, and from there selecting the process and essentially saying to the fake phone, "Debug this process". Neither has really worked. Any other ideas? And just in case...I've run into one blasted technical issue like this after another trying to program for that stupid phone. And I'm not the only one who's having these issues; when I go online to research these issues, it is always very easy for me to find many people who have the same issues, and who are having to use the shottiest, sloppiest, most "ghetto" solutions to work around these issues. I know that many people have created good applications for that phone, but I don't see how I'm supposed to do that when the SDK and the plug-in just don't work half the time. Does anybody know how I may put all this trash behind me, once and for all? Thanks for your answers to either question!

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  • Regular expression for finding non-breaking string names in code and then breaking them up for SQL q

    - by Rob Segal
    I am trying to devlop a regex for finding camel case strings in several code files I am working with so I can break them up into separate words for use in a SQL query. I have strings of the form... EmailAddress FirstName MyNameIs And I want them like this... Email Address First Name My Name Is An example SQL query which I currently have is... select FirstName, MyNameIs from MyTables I need the queries in the form... select FirstName as 'First Name', MyNameIs as 'My Name Is' from MyTables Any time a new capital letter appears that should be a new grouping which I can pick out of the matched string. I currently have the following regex... ([A-Z][a-z]+)+ Which does match the cases I have shown above but when I want to perform a replace I need to define groups. Currently I have tried... (([A-Z])([a-z]+))+ Which sort of works. It will pick out "Address" as the first grouping from "EmailAddress" as opposed to "Email" which is what I was expecting. No doubt there is something I'm misunderstanding here so any help is greatly appreciated.

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  • Message queue proxy in Python + Twisted

    - by gasper_k
    Hi, I want to implement a lightweight Message Queue proxy. It's job is to receive messages from a web application (PHP) and send them to the Message Queue server asynchronously. The reason for this proxy is that the MQ isn't always avaliable and is sometimes lagging, or even down, but I want to make sure the messages are delivered, and the web application returns immediately. So, PHP would send the message to the MQ proxy running on the same host. That proxy would save the messages to SQLite for persistence, in case of crashes. At the same time it would send the messages from SQLite to the MQ in batches when the connection is available, and delete them from SQLite. Now, the way I understand, there are these components in this service: message listener (listens to the messages from PHP and writes them to a Incoming Queue) DB flusher (reads messages from the Incoming Queue and saves them to a database; due to SQLite single-threadedness) MQ connection handler (keeps the connection to the MQ server online by reconnecting) message sender (collects messages from SQlite db and sends them to the MQ server, then removes them from db) I was thinking of using Twisted for #1 (TCPServer), but I'm having problem with integrating it with other points, which aren't event-driven. Intuition tells me that each of these points should be running in a separate thread, because all are IO-bound and independent of each other, but I could easily put them in a single thread. Even though, I couldn't find any good and clear (to me) examples on how to implement this worker thread aside of Twisted's main loop. The example I've started with is the chatserver.py, which uses service.Application and internet.TCPServer objects. If I start my own thread prior to creating TCPServer service, it runs a few times, but the it stops and never runs again. I'm not sure, why this is happening, but it's probably because I don't use threads with Twisted correctly. Any suggestions on how to implement a separate worker thread and keep Twisted? Do you have any alternative architectures in mind?

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  • I am confused -- Will this code always work?

    - by Shekhar
    Hello, I have written this piece of code public class Test{ public static void main(String[] args) { List<Integer> list = new ArrayList<Integer>(); for(int i = 1;i<= 4;i++){ new Thread(new TestTask(i, list)).start(); } while(list.size() != 4){ // this while loop required so that all threads complete their work } System.out.println("List "+list); } } class TestTask implements Runnable{ private int sequence; private List<Integer> list; public TestTask(int sequence, List<Integer> list) { this.sequence = sequence; this.list = list; } @Override public void run() { list.add(sequence); } } This code works and prints all the four elements of list on my machine. My question is that will this code always work. I think there might be a issue in this code when two/or more threads add element to this list at the same point. In that case it while loop will never end and code will fail. Can anybody suggest a better way to do this? I am not very good at multithreading and don't know which concurrent collection i can use? Thanks Shekhar

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  • How should I generate the partitions / pairs for the Chinese Postman problem?

    - by Simucal
    I'm working on a program for class that involves solving the Chinese Postman problem. Our assignment only requires us to write a program to solve it for a hard-coded graph but I'm attempting to solve it for the general case on my own. The part that is giving me trouble is generating the partitions of pairings for the odd vertices. For example, if I had the following labeled odd verticies in a graph: 1 2 3 4 5 6 I need to find all the possible pairings / partitions I can make with these vertices. I've figured out I'll have i paritions given: n = num of odd verticies k = n / 2 i = ((2k)(2k-1)(2k-2)...(k+1))/2 So, given the 6 odd verticies above, we will know that we need to generate i = 15 partitions. The 15 partions would look like: 1 2 3 4 5 6 1 2 3 5 4 6 1 2 3 6 4 5 ... 1 6 ... Then, for each partition, I take each pair and find the shortest distance between them and sum them for that partition. The partition with the total smallest distance between its pairs is selected, and I then double all the edges between the shortest path between the odd vertices (found in the selected partition). These represent the edges the postman will have to walk twice. At first I thought I had worked out an appropriate algorithm for generating these partitions / pairs but it is flawed. I found it wasn't a simple permutation/combination problem. Does anyone who has studied this problem before have any tips that can help point me in the right direction for generating these partitions?

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  • Enabling/Disabling Aero from a Windows Service

    - by rgould
    I have some code to enable/disable the Windows Aero service in Vista, and I would like to run it in a Windows Service. The code works in a standalone application, but when I run it from a Service, nothing happens. No errors or exceptions are thrown. I realise that running code in a service is a different scope than running code in an application, but in this case, how would I enable/disable Aero from the service? Is this even possible? Here is the code I am working with: public static readonly uint DWM_EC_DISABLECOMPOSITION = 0; public static readonly uint DWM_EC_ENABLECOMPOSITION = 1; [DllImport("dwmapi.dll", EntryPoint="DwmEnableComposition")] protected static extern uint Win32DwmEnableComposition(uint uCompositionAction); public static bool EnableAero() { Win32DwmEnableComposition(DWM_EC_ENABLECOMPOSITION); } Edit: It turns out that the DwmEnableComposition call is returning HRESULT 0x80070018, or ERROR_BAD_LENGTH. Seems like a strange error, since the code works when not running as a service. I also tried changing the entire thing to the following code, but got the same result. It sets the window station and desktop, and it seems to be correct, but the call to DwmEnableComposition results in the same error. I've not included the PInvoke declarations for brevity. protected override void OnStop() { IntPtr winStation = OpenWindowStation("winsta0", true, 0x10000000 /* GENERIC_ALL */); if (winStation == null || winStation.ToInt32() == 0) { String err = new Win32Exception(Marshal.GetLastWin32Error()).Message; } if (!SetProcessWindowStation(winStation)) { String err = new Win32Exception(Marshal.GetLastWin32Error()).Message; } uint thread = GetCurrentThreadId(); IntPtr hdesk = OpenInputDesktop(0, false, 0x10000000 /* GENERIC_ALL */); if (hdesk == null || hdesk.ToInt32() == 0) { String err = new Win32Exception(Marshal.GetLastWin32Error()).Message; } if (!SetThreadDesktop(hdesk)) { String err = new Win32Exception(Marshal.GetLastWin32Error()).Message; } uint result = Win32DwmEnableComposition(DWM_EC_DISABLECOMPOSITION); if (result != 0) { String err = new Win32Exception(Marshal.GetLastWin32Error()).Message; } }

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  • How can I create a properly sizing QWebView?

    - by chacham15
    I want to make a QWebView appear expanding to the width and height so that ideally it will have no scroll bars. Some websites may have fixed widths that wont allow this, but I am not concerned with those. In any case, I cannot do as I wish because QWebView implements sizeHint as follows: QSize QWebView::sizeHint() const { return QSize(800, 600); // ####... } This is incorrect on a number of levels. 1. It doesnt at all take into account the size of the actual web page. 2. It doesnt take into account that the height and width are related to each other. (To prove #2 think about text in web pages that wraps to the next line.) As a simple fix I tried to do (where QResizingWebView extends QWebView): QSize QResizingWebView::sizeHint() const{ return this-page()-mainFrame()-contentsSize(); } While this is closer to the result, it also has 2 flaws. 1. It doesnt take into account the relation between the displayed width/height. 2. this->page()->mainFrame()->contentsSize() is inaccurate from what I can tell from my preliminary testing (it has returned heights larger than it should under many cases, although this may be related to #1). Does anyone have any tips to fix this?

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  • Destructors not called when native (C++) exception propagates to CLR component

    - by Phil Nash
    We have a large body of native C++ code, compliled into DLLs. Then we have a couple of dlls containing C++/CLI proxy code to wrap the C++ interfaces. On top of that we have C# code calling into the C++/CLI wrappers. Standard stuff, so far. But we have a lot of cases where native C++ exceptions are allowed to propagate to the .Net world and we rely on .Net's ability to wrap these as System.Exception objects and for the most part this works fine. However we have been finding that destructors of objects in scope at the point of the throw are not being invoked when the exception propagates! After some research we found that this is a fairly well known issue. However the solutions/ workarounds seem less consistent. We did find that if the native code is compiled with /EHa instead of /EHsc the issue disappears (at least in our test case it did). However we would much prefer to use /EHsc as we translate SEH exceptions to C++ exceptions ourselves and we would rather allow the compiler more scope for optimisation. Are there any other workarounds for this issue - other than wrapping every call across the native-managed boundary in a (native) try-catch-throw (in addition to the C++/CLI layer)?

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  • Grails - Language prefix in url mappings

    - by Art79
    Hi there im having problem with language mappings. The way i want it to work is that language is encoded in the url like /appname/de/mycontroller/whatever If you go to /appname/mycontroller/action it should check your session and if there is no session pick language based on browser preference and redirect to the language prefixed site. If you have session then it will display english. English does not have en prefix (to make it harder). So i created mappings like this: class UrlMappings { static mappings = { "/$lang/$controller/$action?/$id?"{ constraints { lang(matches:/pl|en/) } } "/$lang/store/$category" { controller = "storeItem" action = "index" constraints { lang(matches:/pl|en/) } } "/$lang/store" { controller = "storeItem" action = "index" constraints { lang(matches:/pl|en/) } } "/$controller/$action?/$id?"{ lang="en" constraints { } } "/store/$category" { lang="en" controller = "storeItem" action = "index" } "/store" { lang="en" controller = "storeItem" action = "index" } "/"(view:"/index") "500"(view:'/error') } } Its not fully working and langs are hardcoded just for now. I think i did something wrong. Some of the reverse mappings work but some dont add language. If i use link tag and pass params:[lang:'pl'] then it works but if i add params:[lang:'pl', page:2] then it does not. In the second case both lang and page number become parameters in the query string. What is worse they dont affect the locale so page shows in english. Can anyone please point me to the documentation what are the rules of reverse mappings or even better how to implement such language prefix in a good way ? THANKS

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  • NSFetchedResultsController sections localized sorted

    - by Gerd
    How could I use the NSFetchedResultsController with translated sort key and sectionKeyPath? Problem: I have ID in the property "type" in the database like typeA, typeB, typeC,... and not the value directly because it should be localized. In English typeA=Bird, typeB=Cat, typeC=Dog in German it would be Vogel, Katze, Hund. With a NSFetchedResultController with sort key and sectionKeyPath on "type" I receive the order and sections - typeA - typeB - typeC Next I translate for display and everything is fine in English: - Bird - Cat - Dog Now I switch to German and receive a wrong sort order - Vogel - Katze - Hund because it still sorts by typeA, typeB, typeC So I'm looking for a way to localize the sort for the NSFetchedResultsController. I tried the transient property approach, but this doesn't work for the sort key because the sort key need to be in the entity. I have no other idea. But I can't believe that's not possible to use NSFetchedResultsController on a derived attribute required for localization? There are related discussions like http://stackoverflow.com/questions/1384345/using-custom-sections-with-nsfetchedresultscontroller but the difference is that the custom section names and the sort key have probably the same order. Not in my case and this is the main difference. At the end I would need a sort order for the necessary NSSortDescriptor on a derived attribute, I guess. This sort order has also to serve for the sectionKeyPath. Thanks for any hint.

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  • A monkey could do this better - Access to and availability of private member functions in C++

    - by David
    I am wandering the desert of my brain. I'm trying to write something like the following: class MyClass { // Peripherally Related Stuff public: void TakeAnAction(int oneThing, int anotherThing) { switch(oneThing){ case THING_A: TakeThisActionWith(anotherThing); break; //cases THINGS_NOT_A: }; private: void TakeThisActionWith(int thing) { string outcome = new string; outcome = LookUpOutcome(thing); // Do some stuff based on outcome return; } string LookUpOutcome(int key) { string oc = new string; oc = MyPrivateMap[key]; return oc; } map<int, string> MyPrivateMap; Then in the .cc file where I am actually using these things, while compiling the TakeAnAction section, it [CC, the solaris compiler] throws an an error: 'The function LookUpOutcome must have a prototype' and bombs out. In my header file, I have declared 'string LookUpOutcome(int key);' in the private section of the class. I have tried all sorts of variations. I tried to use 'this' for a little while, and it gave me 'Can only use this in non-static member function.' Sadly, I haven't declared anything static and these are all, putatively, member functions. I tried it [on TakeAnAction and LookUp] when I got the error, but I got something like, 'Can't access MyPrivateMap from LookUp'. MyPrivateMap could be made public and I could refer to it directly, I guess, but my sensibility says that is not the right way to go about this [that means that namespace scoped helper functions are out, I think]. I also guess I could just inline the lookup and subsequent other stuff, but my line-o-meter goes on tilt. I'm trying desperately not to kludge it.

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  • Using the Proxy pattern with C++ iterators

    - by Billy ONeal
    Hello everyone :) I've got a moderately complex iterator written which wraps the FindXFile apis on Win32. (See previous question) In order to avoid the overhead of constructing an object that essentially duplicates the work of the WIN32_FIND_DATAW structure, I have a proxy object which simply acts as a sort of const reference to the single WIN32_FIND_DATAW which is declared inside the noncopyable innards of the iterator. This is great because Clients do not pay for construction of irrelevant information they will probably not use (most of the time people are only interested in file names), and Clients can get at all the information provided by the FindXFile APIs if they need or want this information. This becomes an issue though because there is only ever a single copy of the object's actual data. Therefore, when the iterator is incrememnted, all of the proxies are invalidated (set to whatever the next file pointed to by the iterator is). I'm concerned if this is a major problem, because I can think of a case where the proxy object would not behave as somebody would expect: std::vector<MyIterator::value_type> files; std::copy(MyIterator("Hello"), MyIterator(), std::back_inserter(files)); because the vector contains nothing but a bunch of invalid proxies at that point. Instead, clients need to do something like: std::vector<std::wstring> filesToSearch; std::transform( DirectoryIterator<FilesOnly>(L"C:\\Windows\\*"), DirectoryIterator<FilesOnly>(), std::back_inserter(filesToSearch), std::mem_fun_ref(&DirectoryIterator<FilesOnly>::value_type::GetFullFileName) ); Seeing this, I can see why somebody might dislike what the standard library designers did with std::vector<bool>. I'm still wondering though: is this a reasonable trade off in order to achieve (1) and (2) above? If not, is there any way to still achieve (1) and (2) without the proxy?

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  • Can I interrupt javascript code and then continue on a keystroke?

    - by Brian Ramsay
    I am porting an old game from C to Javascript. I have run into an issue with display code where I would like to have the main game code call display methods without having to worry about how those status messages are displayed. In the original code, if the message is too long, the program just waits for the player to toggle through the messages with the spacebar and then continues. This doesn't work in javascript, because while I wait for an event, all of the other program code continues. I had thought to use a callback so that further code can execute when the player hits the designated key, but I can't see how that will be viable with a lot of calls to display.update(msg) scattered throughout the code. Can I architect things differently so the event-based, asynchronous model works, or is there some other solution that would allow me to implement a more traditional event loop? Am I making sense? Example: // this is what the original code does, but obviously doesn't work in Javascript display = { update : function(msg) { // if msg is too long // wait for user input // ok, we've got input, continue } }; // this is more javascript-y... display = { update : function(msg, when_finished) { // show part of the message $(document).addEvent('keydown', function(e) { // display the rest of the message when_finished(); }); } }; // but makes for amazingly nasty game code do_something(param, function() { // in case do_something calls display I have to // provide a callback for everything afterwards // this happens next, but what if do_the_next_thing needs to call display? // I have to wait again do_the_next_thing(param, function() { // now I have to do this again, ad infinitum } }

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  • Practical refactoring using unit tests

    - by awhite
    Having just read the first four chapters of Refactoring: Improving the Design of Existing Code, I embarked on my first refactoring and almost immediately came to a roadblock. It stems from the requirement that before you begin refactoring, you should put unit tests around the legacy code. That allows you to be sure your refactoring didn't change what the original code did (only how it did it). So my first question is this: how do I unit-test a method in legacy code? How can I put a unit test around a 500 line (if I'm lucky) method that doesn't do just one task? It seems to me that I would have to refactor my legacy code just to make it unit-testable. Does anyone have any experience refactoring using unit tests? And, if so, do you have any practical examples you can share with me? My second question is somewhat hard to explain. Here's an example: I want to refactor a legacy method that populates an object from a database record. Wouldn't I have to write a unit test that compares an object retrieved using the old method, with an object retrieved using my refactored method? Otherwise, how would I know that my refactored method produces the same results as the old method? If that is true, then how long do I leave the old deprecated method in the source code? Do I just whack it after I test a few different records? Or, do I need to keep it around for a while in case I encounter a bug in my refactored code? Lastly, since a couple people have asked...the legacy code was originally written in VB6 and then ported to VB.NET with minimal architecture changes.

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  • PostgreSQL, Foreign Keys, Insert speed & Django

    - by Miles
    A few days ago, I ran into an unexpected performance problem with a pretty standard Django setup. For an upcoming feature, we have to regenerate a table hourly, containing about 100k rows of data, 9M on the disk, 10M indexes according to pgAdmin. The problem is that inserting them by whatever method literally takes ages, up to 3 minutes of 100% disk busy time. That's not something you want on a production site. It doesn't matter if the inserts were in a transaction, issued via plain insert, multi-row insert, COPY FROM or even INSERT INTO t1 SELECT * FROM t2. After noticing this isn't Django's fault, I followed a trial and error route, and hey, the problem disappeared after dropping all foreign keys! Instead of 3 minutes, the INSERT INTO SELECT FROM took less than a second to execute, which isn't too surprising for a table <= 20M on the disk. What is weird is that PostgreSQL manages to slow down inserts by 180x just by using 3 foreign keys. Oh, disk activity was pure writing, as everything is cached in RAM; only writes go to the disks. It looks like PostgreSQL is working very hard to touch every row in the referred tables, as 3MB/sec * 180s is way more data than the 20MB this new table takes on disk. No WAL for the 180s case, I was testing in psql directly, in Django, add ~50% overhead for WAL logging. Tried @commit_on_success, same slowness, I had even implemented multi row insert and COPY FROM with psycopg2. That's another weird thing, how can 10M worth of inserts generate 10x 16M log segments? Table layout: id serial primary, a bunch of int32, 3 foreign keys to small table, 198 rows, 16k on disk large table, 1.2M rows, 59 data + 89 index MB on disk large table, 2.2M rows, 198 + 210MB So, am I doomed to either drop the foreign keys manually or use the table in a very un-Django way by defining saving bla_id x3 and skip using models.ForeignKey? I'd love to hear about some magical antidote / pg setting to fix this.

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  • Memory Leak Looping cfmodule inside cffunction

    - by orangepips
    Hoping someone else can confirm or tell me what I'm doing wrong. I am able to consistently reproduce an OOM running by calling the file oom.cfm (shown below). Using jconsole I am able to see the request consumes memory and never releases it until complete. The issue appears to be calling <cfmodule> inside of <cffunction>, where if I comment out the <cfmodule> call things are garbage collected while the request is running. ColdFusion version: 9,0,1,274733 JVM Arguments java.home=C:/Program Files/Java/jdk1.6.0_18 java.args=-server -Xms768m -Xmx768m -Dsun.io.useCanonCaches=false -XX:MaxPermSize=512m -XX:+UseParallelGC -Xbatch -Dcoldfusion.rootDir={application.home}/ -Djava.security.policy={application.home}/servers/41ep8/cfusion.ear/cfusion.war/WEB-INF/cfusion/lib/coldfusion.policy -Djava.security.auth.policy={application.home}/servers/41ep8/cfusion.ear/cfusion.war/WEB-INF/cfusion/lib/neo_jaas.policy -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=56033 Test Case oom.cfm (this calls template.cfm below) <cffunction name="fun" output="false" access="public" returntype="any" hint=""> <cfset var local = structNew()/> <!--- comment out cfmodule and no OOM ---> <cfmodule template="template.cfm"> </cffunction> <cfset size = 1000 * 200> <cfloop from="1" to="#size#" index="idx"> <cfset fun()> <cfif NOT idx mod 1000> <cflog file="se-err" text="#idx# of #size#"> </cfif> </cfloop> template.cfm <!--- I am empty! --->

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  • Unboxing to unknown type

    - by Robert
    I'm trying to figure out syntax that supports unboxing an integral type (short/int/long) to its intrinsic type, when the type itself is unknown. Here is a completely contrived example that demonstrates the concept: // Just a simple container that returns values as objects struct DataStruct { public short ShortVale; public int IntValue; public long LongValue; public object GetBoxedShortValue() { return LongValue; } public object GetBoxedIntValue() { return LongValue; } public object GetBoxedLongValue() { return LongValue; } } static void Main( string[] args ) { DataStruct data; // Initialize data - any value will do data.LongValue = data.IntValue = data.ShortVale = 42; DataStruct newData; // This works if you know the type you are expecting! newData.ShortVale = (short)data.GetBoxedShortValue(); newData.IntValue = (int)data.GetBoxedIntValue(); newData.LongValue = (long)data.GetBoxedLongValue(); // But what about when you don't know? newData.ShortVale = data.GetBoxedShortValue(); // error newData.IntValue = data.GetBoxedIntValue(); // error newData.LongValue = data.GetBoxedLongValue(); // error } In each case, the integral types are consistent, so there should be some form of syntax that says "the object contains a simple type of X, return that as X (even though I don't know what X is)". Because the objects ultimately come from the same source, there really can't be a mismatch (short != long). I apologize for the contrived example, it seemed like the best way to demonstrate the syntax. Thanks.

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  • TypeScript - separating code output

    - by Andrea Baccega
    i'm trying typescript and I find it very useful. I've a quite large project and i was considering rewriting it using typescript. The main problem here is the following: file A.ts: class A extends B { // A stuff } file B.ts: class B { // B stuff } If I compile A.ts with this command: tsc --out compiledA.js A.ts I'll get error from the compiler cause he doesn't know how to threat the "B" after extends. So, a "solution" would be including in A.ts (as first line of code): /// <reference path="./B.ts" /> Compiling again A.ts with the same command tsc --out compiledA.js A.ts Will result in compiledA.js containing both B.ts and A.ts code. ( which could be very nice ) In my case, I only need to compile the A.ts code in the compiledA.js file and I don't want the B.ts stuff to be in there. Indeed, what I want is: tsc --out A.js A.ts = compile only the A.ts stuff tsc --out B.js B.ts = compile only the B.ts stuff I can do it by removing the "extends" keyword but doing that I'll loose most of the typescript goodness. Can someone telll me if there's a way to do this ?

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  • parse content away from structure in a binary file

    - by Jeff Godfrey
    Using C#, I need to read a packed binary file created using FORTRAN. The file is stored in an "Unformatted Sequential" format as described here (about half-way down the page in the "Unformatted Sequential Files" section): http://www.tacc.utexas.edu/services/userguides/intel8/fc/f_ug1/pggfmsp.htm As you can see from the URL, the file is organized into "chunks" of 130 bytes or less and includes 2 length bytes (inserted by the FORTRAN compiler) surrounding each chunk. So, I need to find an efficient way to parse the actual file payload away from the compiler-inserted formatting. Once I've extracted the actual payload from the file, I'll then need to parse it up into its varying data types. That'll be the next exercise. My first thoughts are to slurp up the entire file into a byte array using File.ReadAllBytes. Then, just iterate through the bytes, skipping the formatting and transferring the actual data to a second byte array. In the end, that second byte array should contain the actual file contents minus all the formatting, which I'd then need to go back through to get what I need. As I'm fairly new to C#, I thought there might be a better, more accepted way of tackling this. Also, in case it's helpful, these files could be fairly large (say 30MB), though most will be much smaller...

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