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real time stock quotes, StreamReader performance optimization

- by sean717

I am working on a program that extracts real time quote for 900+ stocks from a website. I use HttpWebRequest to send HTTP request to the site and store the response to a stream and open a stream using the following code: HttpWebResponse response = (HttpWebResponse)request.GetResponse(); Stream stream = response.GetResponseStream (); StreamReader reader = new StreamReader( stream ) the size of the received HTML is large (5000+ lines), so it takes a long time to parse it and extract the price. For 900 files, It takes about 6 mins for parsing and extracting. Which my boss isn't happy with, he told me he'd want the whole process to be done in TWO mins. I've identified the part of the program that takes most of time to finish is parsing and extracting. I've tried to optimize the code to make it faster, the following is what I have now after some optimization: // skip lines at the top for(int i=0;i<1500;++i) reader.ReadLine(); // read the line that contains the price string theLine = reader.ReadLine(); // ... extract the price from the line now it takes about 4 mins to process all the files, there is still a significant gap to what my boss's expecting. So I am wondering, is there other way that I can further speed up the parsing and extracting and have everything done within 2 mins?

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Which pdf elements could cause crashes?

- by Felixyz

This is a very general question but it's based on a specific problem. I've created a pdf reader app for the iPad and it works fine except for certain pdf pages which always crash the app. We now found out that the very same pages cause Safari to crash as well, so as I had started to suspect the problem is somewhere in Apple's pdf rendering code. From what I have been able to see, the crashing pages cause the rendering libraries to start allocating memory like mad until the app is killed. I have nothing else to help me pinpoint what triggers this process. It doesn't necessarily happen with the largest documents, or the ones with the most shapes. In fact, we haven't found any parameter that helps us predict which pages will crash and which not. Now we just discovered that running the pages through a consumer program that lets you merge docs gets rid of the problem, but I haven't been able to detect which attribute or element it is that is the key. Changing documents by hand is also not an option for us in the long run. We need to run an automated process on our server. I'm hoping someone with deeper knowledge about the pdf file format would be able to point me in a reasonable direction to look for document features that could cause this kind of behavior. All I've found so far is something about JBIG2 images, and I don't think we have any of those.

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openDatabase Hello World - 2

- by cf_PhillipSenn

This is a continuation from a previous stackoverflow question. I've renamed some variables so that I can tell what are keywords and what are names that I can control. Q: Why is the deleteRow function not working? <html> <head> <title>html5 openDatabase Hello World</title> <script src="http://www.google.com/jsapi"></script> <script type="text/javascript"> google.load("jquery", "1"); google.setOnLoadCallback(OnLoadCallback); function OnLoadCallback() { var dbo; dbo = openDatabase('HelloWorld'); dbo.transaction( function(T1) { T1.executeSql( 'CREATE TABLE IF NOT EXISTS myTable ' + ' (myTableID INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, ' + ' Field1 TEXT NOT NULL );' ); } ); dbo.transaction(function(T2) { T2.executeSql('SELECT * FROM myTable',[], function (T6, result) { for (var i=0; i < result.rows.length; i++) { var row = result.rows.item(i); $('#savedData').append('<li id="'+row.myTableID+'">' + row.Field1 + '</li>'); } }, errorHandler); }); $('form').submit(function() { var xxx = $('#xxx').val(); dbo.transaction( function(T3) { T3.executeSql( 'INSERT INTO myTable (Field1) VALUES (?);', [xxx], function(){ $('#savedData').append('<li id="ThisisWhereIneedHELP">' + xxx + '</li>'); $('#xxx').val(''); }, errorHandler ); } ); return false; }); $('#savedData > li').live('click', function (){ deleteRow(this.id); $(this).remove(); }); } function deleteRow(myTableID) { alert('trying to delete'); dbo.transaction(function(T4) { T4.executeSql('DELETE FROM myTable WHERE myTableID = ?', [myTableID], function(){ alert('Deleted!'); }, errorHandler); }); } function errorHandler(T5, error) { alert('Oops. Error was '+error.message+' (Code '+error.code+')'); // T5.executeSql('INSERT INTO errors (code, message) VALUES (?, ?);', // [error.code, error.message]); return false; } </script> </head> <body> <form method="post"> <input name="xxx" id="xxx" /> <p> <input type="submit" name="OK" /> </p> <ul id="savedData"> </ul> </form> </body> </html>

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How to get to the key name of a referenced entity property from an entity instance without a datastore read in google app engine?

- by Sumeet Pareek

Consider I have the following models - class Team(db.Model): # say I have just 5 teams name = db.StringProperty() class Player(db.Model): # say I have thousands of players name = db.StringProperty() team = db.ReferenceProperty(Team, collection_name="player_set") Key name for each Team entity = 'team_' , and for each Player entity = 'player_' By some prior arrangement I have a Team entity's (key_name, name) mapping available to me. For example (team_01, United States Of America), (team_02, Russia) etc I have to show all the players and their teams on a page. One way of doing this would be - players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(player.team.name) #This is a total of 1x1000 = 1000 DB reads That is a 1001 DB reads for a silly thing. The interesting part is that when I do a db.to_dict() on players, it shows that for every player in that list there is 'name' of the player and there is the 'key_name' of the team available too. So how can I do the below ?? players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(team_list[player.<SOME WAY OF GETTING TEAM KEY NAME>]) # Here 'team_list' already has (key_name, name) for all 5 teams I have been struggling with this for a long time. Have read every available documentation. I could just hug the person that can help me here :-) Disclaimer: The above problem description is not a real scenario. It is a simplified arrangement that represents my problem exactly. I have run into it in a rater complex and big GAE appication.

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Efficiently Serving Dynamic Content in Google App Engine

- by awegawef

My app on google app engine returns content items (just text) and comments on them. It works like this (pseudo-ish code): query: get keys of latest content #query to datastore for each item in content if item_dict in memcache: use item_dict else: build_item_dict(item) #by fetching from datastore store item_dict in memcache send all item_dicts to template Sorry if the code isn't understandable. I get all of the content dictionaries and send them to the template, which uses them to create the webpage. My problem is that if the memcache has expired, for each item I want to display, I have to (1) lookup item in memcache, (2) since no memcache exists I must fetch item from the datastore, and (3) store the item in memcache. These calls build up quickly. I don't set an expire time for the entries to the memcache, so this really only happens once in the morning, but the webpage takes long enough to load (~1 sec) that the browser reports it as not existing. Regularly, my webpages take about 50ms to load. This approach works decently for frequent visits, but it has its flaws as shown above. How can I remedy this? The entries are dynamic enough that I don't think it would be in my best interest to cache my initial request. Thanks in advance

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Undefined Web.config error in VS 2008

- by user1066050

I'm working on a web app using VS 2008, .Net 3.5 and C#. Most of the projects in the solution are either classic asp.net pages with some MVC 1 in the mix, the rest is shared libraries. The solution is one that is some 5 years old and has gone through a variety of developers working on it and clearly has some performance and architectural issues. Previously, I've been working on the project using VS 2008 on a Win XP machine, but have just transitioned over to a new box using Win 7 Ultimate. To do so, I've installed VS 2008, asp.net 3.5. To support future work on the solution I've also installed VS 2010 and asp.net 4.0. Opening the solution on the new box with VS 2008 works fine, and it builds without error. However, when I attempt to run it with the debugger, I get the following message: "There is an error in web.config. Please correct before proceeding. (You might rename the current web.config and add a new one.)" I think it's clear that there is some sort of environmental issue regarding web.config on the new machine, but the error message is not "helpful". Adding a new web.config is not an option as the existing one is quite long and involved (too much to post here). I'm hoping someone has a suggestion or two about where I might look for missing elements or changed configurations that might produce such an error message. Lacking that, I'll revisit this post and provide the web.config in the hope that will elicit further help. Thanks to all in advance for taking a look at this. The StackOverflow community has helped me many times in the past with pertinent answers although this is my first posting. Jeff

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Encapsulating user input of data for a class (C++)

- by Dr. Monkey

For an assignment I've made a simple C++ program that uses a superclass (Student) and two subclasses (CourseStudent and ResearchStudent) to store a list of students and print out their details, with different details shown for the two different types of students (using overriding of the display() method from Student). My question is about how the program collects input from the user of things like the student name, ID number, unit and fee information (for a course student) and research information (for research students): My implementation has the prompting for user input and the collecting of that input handled within the classes themselves. The reasoning behind this was that each class knows what kind of input it needs, so it makes sense to me to have it know how to ask for it (given an ostream through which to ask and an istream to collect the input from). My lecturer says that the prompting and input should all be handled in the main program, which seems to me somewhat messier, and would make it trickier to extend the program to handle different types of students. I am considering, as a compromise, to make a helper class that handles the prompting and collection of user input for each type of Student, which could then be called on by the main program. The advantage of this would be that the student classes don't have as much in them (so they're cleaner), but also they can be bundled with the helper classes if the input functionality is required. This also means more classes of Student could be added without having to make major changes to the main program, as long as helper classes are provided for these new classes. Also the helper class could be swapped for an alternative language version without having to make any changes to the class itself. What are the major advantages and disadvantages of the three different options for user input (fully encapsulated, helper class or in the main program)?

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Dealing with multiple generics in a method call

- by thaBadDawg

I've been dealing a lot lately with abstract classes that use generics. This is all good and fine because I get a lot of utility out of these classes but now it's making for some rather ugly code down the line. For example: abstract class ClassBase<T> { T Property { get; set; } } class MyClass : ClassBase<string> { OtherClass PropertyDetail { get; set; } } This implementation isn't all that crazy, except when I want to reference the abstract class from a helper class and then I have to make a list of generics just to make reference to the implemented class, like this below. class Helper { void HelpMe<C, T>(object Value) where C : ClassBase<T>, new() { DoWork(); } } This is just a tame example, because I have some method calls where the list of where clauses end up being 5 or 6 lines long to handle all of the generic data. What I'd really like to do is class Helper { void HelpMe<C>(object Value) where C : ClassBase, new() { DoWork(); } } but it obviously won't compile. I want to reference ClassBase without having to pass it a whole array of generic classes to get the function to work, but I don't want to reference the higher level classes because there are a dozen of those. Am I the victim of my own cleverness or is there an avenue that I haven't considered yet?

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Listening for TCP and UDP requests on the same port

- by user339328

I am writing a Client/Server set of programs Depending on the operation requested by the client, I use make TCP or UDP request. Implementing the client side is straight-forward, since I can easily open connection with any protocol and send the request to the server-side. On the servers-side, on the other hand, I would like to listen both for UDP and TCP connections on the same port. Moreover, I like the the server to open new thread for each connection request. I have adopted the approach explained in: link text I have extended this code sample by creating new threads for each TCP/UDP request. This works correctly if I use TCP only, but it fails when I attempt to make UDP bindings. Please give me any suggestion how can I correct this. tnx Here is the Server Code: public class Server { public static void main(String args[]) { try { int port = 4444; if (args.length > 0) port = Integer.parseInt(args[0]); SocketAddress localport = new InetSocketAddress(port); // Create and bind a tcp channel to listen for connections on. ServerSocketChannel tcpserver = ServerSocketChannel.open(); tcpserver.socket().bind(localport); // Also create and bind a DatagramChannel to listen on. DatagramChannel udpserver = DatagramChannel.open(); udpserver.socket().bind(localport); // Specify non-blocking mode for both channels, since our // Selector object will be doing the blocking for us. tcpserver.configureBlocking(false); udpserver.configureBlocking(false); // The Selector object is what allows us to block while waiting // for activity on either of the two channels. Selector selector = Selector.open(); tcpserver.register(selector, SelectionKey.OP_ACCEPT); udpserver.register(selector, SelectionKey.OP_READ); System.out.println("Server Sterted on port: " + port + "!"); //Load Map Utils.LoadMap("mapa"); System.out.println("Server map ... LOADED!"); // Now loop forever, processing client connections while(true) { try { selector.select(); Set<SelectionKey> keys = selector.selectedKeys(); // Iterate through the Set of keys. for (Iterator<SelectionKey> i = keys.iterator(); i.hasNext();) { SelectionKey key = i.next(); i.remove(); Channel c = key.channel(); if (key.isAcceptable() && c == tcpserver) { new TCPThread(tcpserver.accept().socket()).start(); } else if (key.isReadable() && c == udpserver) { new UDPThread(udpserver.socket()).start(); } } } catch (Exception e) { e.printStackTrace(); } } } catch (Exception e) { e.printStackTrace(); System.err.println(e); System.exit(1); } } } The UDPThread code: public class UDPThread extends Thread { private DatagramSocket socket = null; public UDPThread(DatagramSocket socket) { super("UDPThread"); this.socket = socket; } @Override public void run() { byte[] buffer = new byte[2048]; try { DatagramPacket packet = new DatagramPacket(buffer, buffer.length); socket.receive(packet); String inputLine = new String(buffer); String outputLine = Utils.processCommand(inputLine.trim()); DatagramPacket reply = new DatagramPacket(outputLine.getBytes(), outputLine.getBytes().length, packet.getAddress(), packet.getPort()); socket.send(reply); } catch (IOException e) { e.printStackTrace(); } socket.close(); } } I receive: Exception in thread "UDPThread" java.nio.channels.IllegalBlockingModeException at sun.nio.ch.DatagramSocketAdaptor.receive(Unknown Source) at server.UDPThread.run(UDPThread.java:25) 10x

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Why does Hibernate 2nd level cache only cache queries within a session?

- by Synesso

Using a named query in our application and with ehcache as the provider, it seems that the query results are tied to the session within the cache. Any attempt to access the value from the cache for a second time results in a LazyInitializationException We have set lazy = true for the following mapping because this object is also used by another part of the system which does not require the reference... and we want to keep it lean. <class name="domain.ReferenceAdPoint" table="ad_point" mutable="false" lazy="false"> <cache usage="read-only"/> <id name="code" type="long" column="ad_point_id"> <generator class="assigned" /> </id> <property name="name" column="ad_point_description" type="string"/> <set name="synonyms" table="ad_point_synonym" cascade="all-delete-orphan" lazy="true"> <cache usage="read-only"/> <key column="ad_point_id" /> <element type="string" column="synonym_description" /> </set> </class> <query name="find.adpoints.by.heading">from ReferenceAdPoint adpoint left outer join fetch adpoint.synonyms where adpoint.adPointField.headingCode = ?</query> Here's a snippet from our hibernate.cfg.xml <property name="hibernate.cache.provider_class">net.sf.ehcache.hibernate.SingletonEhCacheProvider</property> <property name="hibernate.cache.use_query_cache">true</property> It doesn't seem to make sense that the cache would be constrained to the session. Why are the cached queries not usable outside of the (relatively short-lived) sessions?

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Android ArrayList<Location> passing between activities

- by squixy

I have simple class Track, which stores information about route: import java.io.Serializable; import java.util.ArrayList; import java.util.Date; import android.location.Location; public class Track implements Serializable { private static final long serialVersionUID = -5317697499269650204L; private Date date; private String name; private int time; private double distance, speed; private ArrayList<Location> route; public Track(String name, int time, double distance, ArrayList<Location> route) { this.date = new Date(); this.name = name; this.time = time; this.distance = distance; this.speed = distance / (time / 3600.); this.route = route; } public String getDate() { return String.format("Date: %1$td-%1$tb-%1$tY%nTime: %1$tH:%1$tM:%1$tS", date); } public String getName() { return name; } public int getTime() { return time; } public double getDistance() { return distance; } public float getSpeed() { return (float) speed; } public ArrayList<Location> getRoute() { return route; } @Override public String toString() { return String.format("Name: %s%nDate: %2$td-%2$tb-%2$tY%nTime: %2$tH:%2$tM:%2$tS", name, date); } } And I'm passing it from one activity to another: Intent showTrackIntent = new Intent(TabSavedActivity.this, ShowTrackActivity.class); showTrackIntent.putExtra("track", adapter.getItem(position)); startActivity(showTrackIntent); Where (Track object is element on ListView). I get error during passing Track object: java.lang.RuntimeException: Parcelable encountered IOException writing serializable object (name = classes.Track) What is happening?

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JVM GC demote object to eden space?

- by Kevin

I'm guessing this isn't possible...but here goes. My understanding is that eden space is cheaper to collect than old gen space, especially when you start getting into very large heaps. Large heaps tend to come up with long running applications (server apps) and server apps a lot of the time want to use some kind of caches. Caches with some kind of eviction (LRU) tend to defeat some assumptions that GC makes (temporary objects die quickly). So cache evictions end up filling up old gen faster than you'd like and you end up with a more costly old gen collection. Now, it seems like this sort of thing could be avoided if java provided a way to mark a reference as about to die (delete keyword)? The difference between this and c++ is that the use is optional. And calling delete does not actually delete the object, but rather is a hint to the GC that it should demote the object back to Eden space (where it will be more easily collected). I'm guessing this feature doesn't exist, but, why not (is there a reason it's a bad idea)?

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Proper way to scan a range of IP addresses

- by Josh G

Given a range of IP addresses entered by a user (through various means), I want to identify which of these machines have software running that I can talk to. Here's the basic process: Ping these addresses to find available machines Connect to a known socket on the available machines Send a message to the successfully established sockets Compare the response to the expected response Steps 2-4 are straight forward for me. What is the best way to implement the first step in .NET? I'm looking at the System.Net.NetworkInformation.Ping class. Should I ping multiple addresses simultaneously to speed up the process? If I ping one address at a time with a long timeout it could take forever. But with a small timeout, I may miss some machines that are available. Sometimes pings appear to be failing even when I know that the address points to an active machine. Do I need to ping twice in the event of the request getting discarded? To top it all off, when I scan large collections of addresses with the network cable unplugged, Ping throws a NullReferenceException in FreeUnmanagedResources(). !? Any pointers on the best approach to scanning a range of IPs like this?

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Is there a FAST way to export and install an app on my phone, while signing it with my own keystore?

- by Alexei Andreev

So, I've downloaded my own application from the market and installed it on my phone. Now, I am trying to install a temporary new version from Eclipse, but here is the message I get: Re-installation failed due to different application signatures. You must perform a full uninstall of the application. WARNING: This will remove the application data! Please execute 'adb uninstall com.applicationName' in a shell. Launch canceled! Now, I really really don't want to uninstall the application, because I will lose all my data. One solution I found is to Export my application, creating new .apk, and then install it via HTC Sync (probably a different program based on what phone you have). The problem is this takes a long time to do, since I need to enter the password for the keystore each time and then wait for HTC Sync. It's a pain in the ass! So the question is: Is there a way to make Eclipse automatically use my keystore to sign the application (quickly and automatically)? Or perhaps to replace debug keystore with my own? Or perhaps just tell it to remember the password, so I don't have to enter it every time...? Or some other way to solve this problem?

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Exception handling in Spring MVC with 3 layer architecture

- by Chorochrondochor

I am building a simple web applications with 3 layers - DAO, Service, MVC. When in my Controller I want to delete menu group and it contains menus I am getting ConstraintViolationException. Where should I handle this exception? In DAO, Service, or in Controller? Currently I am handling the exception in Controller. My code below. DAO method for deleting menu groups: @Override public void delete(E e){ if (e == null){ throw new DaoException("Entity can't be null."); } getCurrentSession().delete(e); } Service method for deleting menu groups: @Override @Transactional(readOnly = false) public void delete(MenuGroupEntity menuGroupEntity) { menuGroupDao.delete(menuGroupEntity); } Controller method for deleting menu groups in Controller: @RequestMapping(value = "/{menuGroupId}/delete", method = RequestMethod.GET) public ModelAndView delete(@PathVariable Long menuGroupId, RedirectAttributes redirectAttributes){ MenuGroupEntity menuGroupEntity = menuGroupService.find(menuGroupId); if (menuGroupEntity != null){ try { menuGroupService.delete(menuGroupEntity); redirectAttributes.addFlashAttribute("flashMessage", "admin.menu-group-deleted"); redirectAttributes.addFlashAttribute("flashMessageType", "success"); } catch (Exception e){ redirectAttributes.addFlashAttribute("flashMessage", "admin.menu-group-could-not-be-deleted"); redirectAttributes.addFlashAttribute("flashMessageType", "danger"); } } return new ModelAndView("redirect:/admin/menu-group"); }

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Simulating a contains If-Else using RewriteCond

- by hlissner

Hi! I'm trying to get my head around RewriteCond, and want to rewrite any requests either to a static html page (if it exists), or to a specific index.php (so long as the requested file doesn't exist). To illustrate the logic: if HTTP_HOST is '(www\.)?mydomain.com' if file exists: "/default/static/{REQUEST_URI}.html", then rewrite .* to /default/static/{REQUEST_URI}.html else if file exists: {REQUEST_FILENAME}, then do not rewrite else rewrite .* to /default/index.php I don't seem to have much trouble doing it when I don't need to test for the HTTP_HOST. Ultimately, this one .htaccess file will be handling requests for several domains. I know I could get around this with vhosts, but I'd like to figure out how to do it this way. Here's where I am at now: RewriteCond %{HTTP_HOST} ^(www\.)?mydomain\.com$ [NC] RewriteCond /default/static/%{REQUEST_URI}.html -f RewriteRule . /default/static/%{REQUEST_URI}.html [L,NC] RewriteCond %{REQUEST_FILENAME} !-f RewriteRule . /default/index.php [L,QSA] I'm not too familiar with some of the other flags, will any of them be of use here (like chain|C, next|N or skip|S)? Thanks in advance!

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Should I use IDisposable for purely managed resources?

- by John Gietzen

Here is the scenario: I have an object called a Transaction that needs to make sure that only one entity has permission to edit it at any given time. In order to facilitate a long-lived lock, I have the class generating a token object that can be used to make the edits. You would use it like this: var transaction = new Transaction(); using (var tlock = transaction.Lock()) { transaction.Update(data, tlock); } Now, I want the TransactionLock class to implement IDisposable so that its usage can be clear. But, I don't have any unmanaged resources to dispose. however, the TransctionLock object itself is a sort of "unmanaged resource" in the sense that the CLR doesn't know how to properly finalize it. All of this would be fine and dandy, I would just use IDisposable and be done with it. However, my issue comes when I try to do this in the finalizer: ~TransactionLock() { this.Dispose(false); } I want the finalizer to release the transaction from the lock, if possible. How, in the finalizer, do I detect if the parent transaction (this.transaction) has already been finalized? Is there a better pattern I should be using? The Transaction class looks something like this: public sealed class Transaction { private readonly object lockMutex = new object(); private TransactionLock currentLock; public TransactionLock Lock() { lock (this.lockMutex) { if (this.currentLock != null) throw new InvalidOperationException(/* ... */); this.currentLock = new TransactionLock(this); return this.currentLock; } } public void Update(object data, TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); // ... } } internal void ValidateLock(TransactionLock tlock) { if (this.currentLock == null) throw new InvalidOperationException(/* ... */); if (this.currentLock != tlock) throw new InvalidOperationException(/* ... */); } internal void Unlock(TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); this.currentLock = null; } } }

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Java Script in Rails 3.1 works only in certain parts. Any idea why?

- by Sergio Nekora

This might seem a bit weird, but since I am new in RoR and cannot find any similar questions I thought you might know. The situation is that JavaScript does not work throughout my whole site. For instance. For the sake of checking, I place a link with an alert function in the footer. It did not work at the beginning, it felt like the JS was disabled(but it wasn't). But eventually it worked. Now it works in most the pages but it does not work in one that there is also an 'autocomplete' field. Of course, this autocomplete field does not work either. That could lead you to think that there is something wrong with the autocomplete code. However this same code is working in the sidebar. Any ideas why? Could it have anything to do with the fact that one day my assets folder appeared empty? After installing the gmaps4rails gem I realized that all my Js and CSS files were gone from my assests folder. Ok, it might have happened long before and I just realized at that point. I don't really know. Here in the root you can see that the 'Hola sip' click at the button works. here it works However, here same link does not trigger the alert function. here it doesn't

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Generic version control strategy for select table data within a heavily normalized database

- by leppie

Hi Sorry for the long winded title, but the requirement/problem is rather specific. With reference to the following sample (but very simplified) structure (in psuedo SQL), I hope to explain it a bit better. TABLE StructureName { Id GUID PK, Name varchar(50) NOT NULL } TABLE Structure { Id GUID PK, ParentId GUID (FK to Structure), NameId GUID (FK to StructureName) NOT NULL } TABLE Something { Id GUID PK, RootStructureId GUID (FK to Structure) NOT NULL } As one can see, Structure is a simple tree structure (not worried about ordering of children for the problem). StructureName is a simplification of a translation system. Finally 'Something' is simply something referencing the tree's root structure. This is just one of many tables that need to be versioned, but this one serves as a good example for most cases. There is a requirement to version to any changes to the name and/or the tree 'layout' of the Structure table. Previous versions should always be available. There seems to be a few possibilities to tackle this issue, like copying the entire structure, but most approaches causes one to 'loose' referential integrity. Example if one followed this approach, one would have to make a duplicate of the 'Something' record, given that the root structure will be a new record, and have a new ID. Other avenues of possible solutions are looking into how Wiki's handle this or go a lot further and look how proper version control systems work. Currently, I feel a bit clueless how to proceed on this in a generic way. Any ideas will be greatly appreciated. Thanks leppie

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How to increase PermGen memory for eclipselink StaticWeaveAntTask

- by rayd09

We are using Eclipselink and need to weave the code in order for lazy fetching to work property. During the weave process I'm getting the following error: weave: BUILD FAILED java.lang.OutOfMemoryError: PermGen space I have the following tasks within my ant build file: <target name="define_weave_task" description="task definition for EclipseLink static weaving"> <taskdef name="eclipse_weave" classname="org.eclipse.persistence.tools.weaving.jpa.StaticWeaveAntTask"/> </target> <target name="weave" depends="compile,define_weave_task" description="weave eclipselink code into compiled classes"> <eclipse_weave source="${path.classes}" target="${path.classes}"> <classpath refid="compile.classpath"/> </eclipse_weave> </target> It has been working great for a long time. Now that the amount of code to be woven has increased I'm getting the PermGen error. I would like to be able to up the amount of perm space. If I was doing a compile I would be able to up the perm space via a compiler argument such as <compilerarg value="-XX:MaxPermSize=256M"/> but this does not appear to be a valid argument for eclipselink weaving. How can I up the perm space for the weave?

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Problem with sprintf function, last parameters are wrong when written

- by Apoc

So I use sprintf sprintf(buffer,"%f|%f|%f|%f|%f|%f|%d|%f|%d", x, y, z, u, v, w, nID,dDistance, nConfig) But when I print the buffer I get the 2 last parameters wrong, they are lets suppose to be 35.0000 and 0 and in the string they are 0.00000 and 10332430 and my buffer is long enough and all the other parameters are good in the string Any idea? Is there a length limit to sprintf or something^ I checked the types of all the numbers and they are right, but what seems to be the problem is the dDistance. When I remove it from the sprint, the nConfig gets the right value in the string, but when I remove nConfig, dDistance still doesn't get the right value. I checked and dDistance is a double. Any idea? Since people don't seem to believe me I did this : char test[255]={0}; int test1 = 2; double test2=35.00; int test3 = 0; sprintf(test,"%d|%f|%d",test1,test2,test3); and I get this in my string: 2|0.000000|1078034432

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Android OS 2.2 Permissions: I have absolutely no idea why this simple piece of code doesn't work. Wh

- by Kevin

I'm just playing around with some code. I create an Activity and simply do something like this: long lo = currentTimeMillis(); System.out.println(lo); lo *= 3; System.out.println(lo); SystemClock.setCurrentTimeMillis(lo); System.out.println( currentTimeMillis() ); Yes, in my AndroidManifest.xml, I've added: <uses-permission android:name="android.permission.SET_TIME"></uses-permission> <uses-permission android:name="android.permission.SET_TIME_ZONE"></uses-permission> Nothing changes. The SystemClock is never reset...it just keeps on ticking. The error that I'm getting just says that the permission "SET_TIME" was not granted to the program. Protection level 3. The permissions are there...and in the API for 2.2 it says that this feature is supported now. I have no idea what I'm doing wrong. If android.content.Intent; comes into play, please explain. I don't really understand what the idea behind intents! Thanks for any help!

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In Fluent NHibernate, how would I map the following domain models?

- by Brandon

I have a user class that looks something like this public class User { public virtual int Id { get; set; } public virtual long ValueA { get; set; } public virtual int? ValueB { get; set; } } ValueA is automatically assigned by the system. It is used in a lookup that would map to UserClass. However, if a value for ValueB exists, then it would do the lookup for UserClass in a different way. Right now the way I handle it is to get the User and then perform a separate lookup each time. return user.ValueB.HasValue ? Find(user.ValueB.Value) : Find(user.ValueA); Is there any way to make Fluent NHibernate do this for me so I can have UserClass as a property on the User class instead of having to do the lookup separately? I was thinking of the ComponentMap but I'm not sure how to make it account for the two possible lookup values.

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Basic security, PHP mySQl

- by yuudachi

So I am making a basic log-in page. I have a good idea of what to do, but I'm still unsure of some things. I have a database full of students and a password column of course. I know I'm going to use md5 encryption in that column. The student enters their e-mail and student ID, and they get e-mailed a password if correct. But, where do I create the password? Do I have to manually add the password (which is just a randomly generated string) in mySQL to all the students? And I am suppose to send the password to the student; how will I know what to send the student if the password is encrypted? I was thinking about generating the password when the student first enters their e-mail and student ID. They get an e-mail of the random string, and at the same time, I add the same random string to the database, encrypted. Is that how it's suppose to work though? And it feels unsafe doing that all on the same page. Sorry for the long-winded, newbish question. I find this all facisnating at the same time as well (AES and RSA encryption :O)

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Creating a complex tree model in Qt

- by Zeke

I'm writing an IRC Client (yes another one). Long story short. I'm writing a Server dialogue that keeps a list of this: Identity Networks Channels Addresses I have 3 different list views that will be for the Networks, Channels and Addresses. When the user changes the Identity (combo box). The network listview will lookup all the networks for that specific Identity. After it loads up the Networks it will automatically select the first network and then load all the channels and addresses for that specific network. The problem is I want to have 3 views for 1 model, to minimise all the memory and the loading of data. So that it makes it much easier to manage and not do a bunch of work. If you'd look at QColumnView it's the same exact thing. But I don't need it to be on one exact page since the views are on entirely different tabs to make it easier to go through the Server dialogue. I'm wondering what will be the best way to go about handling this complexity. The information is stored in a SQLite database. I already have the classes written to extract and store it. Just the modelling is the painful part of this solution.

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