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  • Best Practice: What can be the hashCode() method implementation if custom field used in equals() method are null?

    - by goodspeed
    What is the best practice to return a value for hashCode() method if custom field used in equals are null ? I have a situation, where equals() override is implemented using custom fields. Usually it it is better to override hashCode() also using that custom fields used in equals(). But if all the custom fields used in equals() are null, then what would be the best implementation for hashCode()? Example: class Person { private String firstName; private String lastName; public String getFirstName() { return firstName; } public String getLastName() { return lastName; } @Override public boolean equals(Object object) { boolean result = false; if (object == null || object.getClass() != getClass()) { result = false; } else { Person person = (Person) object; if (this.firstName == person.getFirstName() && this.lastName == tiger.getLastName()) { result = true; } } return result; } @Override public int hashCode() { int hash = 3; if(this.firstName == null || this.lastName == null) { // <b>What is the best practice here, </b> // <b>is return super.hashCode() better ?</b> } hash = 7 * hash + this.firstName.hashCode(); hash = 7 * hash + this.lastName.hashCode(); return hash; } } is it required to check for null in hashCode() ? If yes, what should be returned if custom values are null ?

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  • Style list of divs as 2 column layout with css

    - by Anders Svensson
    I'm trying out ASP.NET MVC 2 by going through the "NerdDinner" tutorial. But apparently version 2 of MVC doesn't create a Details page the same as in the tutorial, and you get divs with css classes on them to style. However, I want to get the style where each label is followed on the same line with the field, and I can't do it, I get them on top of each other, or if I try using floats weird things happen (probably because I don't know exactly how to use it in this situation, where every other div should be on the same line). Here's the generated html for the Details page: <fieldset> <legend>Fields</legend> <div> <div class="display-label">DinnerID</div> <div class="display-field"><%: Model.DinnerID %></div> <div class="display-label">Title</div> <div class="display-field"><%: Model.Title %></div> <div class="display-label">EventDate</div> <div class="display-field"><%: String.Format("{0:g}", Model.EventDate) %></div> <div class="display-label">Description</div> <div class="display-field"><%: Model.Description %></div> <div class="display-label">HostedBy</div> <div class="display-field"><%: Model.HostedBy %></div> <div class="display-label">ContactPhone</div> <div class="display-field"><%: Model.ContactPhone %></div> <div class="display-label">Address</div> <div class="display-field"><%: Model.Address %></div> <div class="display-label">Country</div> <div class="display-field"><%: Model.Country %></div> <div class="display-label">Latitude</div> <div class="display-field"><%: String.Format("{0:F}", Model.Latitude) %></div> <div class="display-label">Longitude</div> <div class="display-field"><%: String.Format("{0:F}", Model.Longitude) %></div> <div class="display-label">IsValid</div> <div class="display-field"><%: Model.IsValid %></div> </div> </fieldset> How do I get the display-label and display-field for each "entry" to appear on the same line?

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  • In Rails, how should I implement a Status field for a Tasks app - integer or enum?

    - by Doug
    For a Rails 3.0 Todo app, I have a Tasks model with a Status field. What's the best way to store the Status field data (field type) and still display a human-readable version in a view (HTML table)? Status can be: 0 = Normal 1 = Active 2 = Completed Right now I have this: Rails Schema Here: create_table "tasks", :force = true do |t| t.integer "status", :limit = 1, :default = 0, :null = false Rails Model Here: class Task < ActiveRecord::Base validates_inclusion_of :status, :in => 0..2, :message => "{{value}} must be 0, 1, or 2" Rails View Here: <h1>Listing tasks</h1> <table> <tr> <th>Status</th> <th>Name</th> <th></th> <th></th> <th></th> </tr> <% @tasks.each do |task| %> <tr> <td><%= task.status %></td> <td><%= task.name %></td> <td><%= link_to 'Show', task %></td> <td><%= link_to 'Edit', edit_task_path(task) %></td> <td><%= link_to 'Delete', task, :confirm => 'Are you sure?', :method => :delete %></td> </tr> <% end %> </table> Requirements Store a Task's status in the db such that the values are easily localizable, i.e. I'm not sure I want to store "normal", "active", "completed" as a string field. Solution must work with Rails 3.0. Questions: Should I store the field as an integer (see above)? If so, how do I display the correct human readable status in an HTML table in my Rails view, e.g. show "Active" instead of "1" in the HTML table. Should I use an enum? If so, is this easy to localize later? Should I use straight strings, e.g. "Normal", "Active", "Completed" Can you provide a quick code sample of the view helper, controller or view code to make this work?

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  • Quick guide to Oracle IRM 11g: Configuring SSL

    - by Simon Thorpe
    Quick guide to Oracle IRM 11g index So far in this guide we have an IRM Server up and running, however I skipped over SSL configuration in the previous article because I wanted to focus in more detail now. You can, if you wish, not bother with setting up SSL, but considering this is a security technology it is worthwhile doing. Contents Setting up a one way, self signed SSL certificate in WebLogic Setting up an official SSL certificate in Apache 2.x Configuring Apache to proxy traffic to the IRM server There are two common scenarios in which an Oracle IRM server is configured. For a development or evaluation system, people usually communicate directly to the WebLogic Server running the IRM service. However in a production environment and for some proof of concept evaluations that require a setup reflecting a production system, the traffic to the IRM server travels via a web server proxy, commonly Apache. In this guide we are building an Oracle Enterprise Linux based IRM service and this article will go over the configuration of SSL in WebLogic and also in Apache. Like in the past articles, we are going to use two host names in the configuration below,irm.company.com will refer to the public Apache server irm.company.internal will refer to the internal WebLogic IRM server Setting up a one way, self signed SSL certificate in WebLogic First lets look at creating just a simple self signed SSL certificate to be used in WebLogic. This is a quick and easy way to get SSL working in your environment, however the downside is that no browsers are going to trust this certificate you create and you'll need to manually install the certificate onto any machine's communicating with the server. This is fine for development or when you have only a few users evaluating the system, but for any significant use it's usually better to have a fully trusted certificate in use and I explain that in the next section. But for now lets go through creating, installing and testing a self signed certificate. We use a library in Java to create the certificates, open a console and running the following commands. Note you should choose your own secure passwords whenever you see password below. [oracle@irm /] source /oracle/middleware/wlserver_10.3/server/bin/setWLSEnv.sh [oracle@irm /] cd /oracle/middleware/user_projects/domains/irm_domain/config/fmwconfig/ [oracle@irm /] java utils.CertGen -selfsigned -certfile MyOwnSelfCA.cer -keyfile MyOwnSelfKey.key -keyfilepass password -cn "irm.oracle.demo" [oracle@irm /] java utils.ImportPrivateKey -keystore MyOwnIdentityStore.jks -storepass password -keypass password -alias trustself -certfile MyOwnSelfCA.cer.pem -keyfile MyOwnSelfKey.key.pem -keyfilepass password [oracle@irm /] keytool -import -trustcacerts -alias trustself -keystore TrustMyOwnSelf.jks -file MyOwnSelfCA.cer.der -keyalg RSA We now have two Java Key Stores, MyOwnIdentityStore.jks and TrustMyOwnSelf.jks. These contain keys and certificates which we will use in WebLogic Server. Now we need to tell the IRM server to use these stores when setting up SSL connections for incoming requests. Make sure the Admin server is running and login into the WebLogic Console at http://irm.company.intranet:7001/console and do the following; In the menu on the left, select the + next to Environment to expose the submenu, then click on Servers. You will see two servers in the list, AdminServer(admin) and IRM_server1. If the IRM server is running, shut it down either by hitting CONTROL + C in the console window it was started from, or you can switch to the CONTROL tab, select IRM_server1 and then select the Shutdown menu and then Force Shutdown Now. In the Configuration tab select IRM_server1 and switch to the Keystores tab. By default WebLogic Server uses it's own demo identity and trust. We are now going to switch to the self signed one's we've just created. So select the Change button and switch to Custom Identity and Custom Trust and hit save. Now we have to complete the resulting fields, the setting's i've used in my evaluation server are below. IdentityCustom Identity Keystore: /oracle/middleware/user_projects/domains/irm_domain/config/fmwconfig/MyOwnIdentityStore.jks Custom Identity Keystore Type: JKS Custom Identity Keystore Passphrase: password Confirm Custom Identity Keystore Passphrase: password TrustCustom Trust Keystore: /oracle/middleware/user_projects/domains/irm_domain/config/fmwconfig/TrustMyOwnSelf.jks Custom Trust Keystore Type: JKS Custom Trust Keystore Passphrase: password Confirm Custom Trust Keystore Passphrase: password Now click on the SSL tab for the IRM_server1 and enter in the alias and passphrase, in my demo here the details are; IdentityPrivate Key Alias: trustself Private Key Passphrase: password Confirm Private Key Passphrase: password And hit save. Now lets test a connection to the IRM server over HTTPS using SSL. Go back to a console window and start the IRM server, a quick reminder on how to do this is... [oracle@irm /] cd /oracle/middleware/user_projects/domains/irm_domain/bin [oracle@irm /] ./startManagedWeblogic IRM_server1 Once running, open a browser and head to the SSL port of the server. By default the IRM server will be listening on the URL https://irm.company.intranet:16101/irm_rights. Note in the example image on the right the port is 7002 because it's a system that has the IRM services installed on the Admin server, this isn't typical (or advisable). Your system is going to have a separate managed server which will be listening on port 16101. Once you open this address you will notice that your browser is going to complain that the server certificate is untrusted. The images on the right show how Firefox displays this error. You are going to be prompted every time you create a new SSL session with the server, both from the browser and more annoyingly from the IRM Desktop. If you plan on always using a self signed certificate, it is worth adding it to the Windows certificate store so that when you are accessing sealed content you do not keep being informed this certificate is not trusted. Follow these instructions (which are for Internet Explorer 8, they may vary for your version of IE.) Start Internet Explorer and open the URL to your IRM server over SSL, e.g. https://irm.company.intranet:16101/irm_rights. IE will complain that about the certificate, click on Continue to this website (not recommended). From the IE Tools menu select Internet Options and from the resulting dialog select Security and then click on Trusted Sites and then the Sites button. Add to the list of trusted sites a URL which mates the server you are accessing, e.g. https://irm.company.intranet/ and select OK. Now refresh the page you were accessing and next to the URL you should see a red cross and the words Certificate Error. Click on this button and select View Certificates. You will now see a dialog with the details of the self signed certificate and the Install Certificate... button should be enabled. Click on this to start the wizard. Click next and you'll be asked where you should install the certificate. Change the option to Place all certificates in the following store. Select browse and choose the Trusted Root Certification Authorities location and hit OK. You'll then be prompted to install the certificate and answer yes. You also need to import the root signed certificate into the same location, so once again select the red Certificate Error option and this time when viewing the certificate, switch to the Certification Path tab and you should see a CertGenCAB certificate. Select this and then click on View Certificate and go through the same process as above to import the certificate into the store. Finally close all instances of the IE browser and re-access the IRM server URL again, this time you should not receive any errors. Setting up an official SSL certificate in Apache 2.x At this point we now have an IRM server that you can communicate with over SSL. However this certificate isn't trusted by any browser because it's path of trust doesn't end in a recognized certificate authority (CA). Also you are communicating directly to the WebLogic Server over a non standard SSL port, 16101. In a production environment it is common to have another device handle the initial public internet traffic and then proxy this to the WebLogic server. The diagram below shows a very simplified view of this type of deployment. What i'm going to walk through next is configuring Apache to proxy traffic to a WebLogic server and also to use a real SSL certificate from an official CA. First step is to configure Apache to handle incoming requests over SSL. In this guide I am configuring the IRM service in Oracle Enterprise Linux 5 update 3 and Apache 2.2.3 which came with OpenSSL and mod_ssl components. Before I purchase an SSL certificate, I need to generate a certificate request from the server. Oracle.com uses Verisign and for my own personal needs I use cheaper certificates from GoDaddy. The following instructions are specific to Apache, but there are many references out there for other web servers. For Apache I have OpenSSL and the commands are; [oracle@irm /] cd /usr/bin [oracle@irm bin] openssl genrsa -des3 -out irm-apache-server.key 2048 Generating RSA private key, 2048 bit long modulus ............................+++ .........+++ e is 65537 (0x10001) Enter pass phrase for irm-apache-server.key: Verifying - Enter pass phrase for irm-apache-server.key: [oracle@irm bin] openssl req -new -key irm-apache-server.key -out irm-apache-server.csr Enter pass phrase for irm-apache-server.key: You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [GB]:US State or Province Name (full name) [Berkshire]:CA Locality Name (eg, city) [Newbury]:San Francisco Organization Name (eg, company) [My Company Ltd]:Oracle Organizational Unit Name (eg, section) []:Security Common Name (eg, your name or your server's hostname) []:irm.company.com Email Address []:[email protected] Please enter the following 'extra' attributes to be sent with your certificate request A challenge password []:testing An optional company name []: You must make sure to remember the pass phrase you used in the initial key generation, you will need this when later configuring Apache. In the /usr/bin directory there are now two new files. The irm-apache-server.csr contains our certificate request and is what you cut and paste, or upload, to your certificate authority when you purchase and validate your SSL certificate. In response you will typically get two files. Your server certificate and another certificate file that will likely contain a set of certificates from your CA which validate your certificate's trust. Next we need to configure Apache to use these files. Typically there is an ssl.conf file which is where all the SSL configuration is done. On my Oracle Enterprise Linux server this file is located in /etc/httpd/conf.d/ssl.conf and i've added the following lines. <VirtualHost irm.company.com> # Setup SSL for irm.company.com ServerName irm.company.com SSLEngine On SSLCertificateFile /oracle/secure/irm.company.com.crt SSLCertificateKeyFile /oracle/secure/irm.company.com.key SSLCertificateChainFile /oracle/secure/gd_bundle.crt </VirtualHost> Restarting Apache (apachectl restart) and I can now attempt to connect to the Apache server in a web browser, https://irm.company.com/. If all is configured correctly I should now see an Apache test page delivered to me over HTTPS. Configuring Apache to proxy traffic to the IRM server Final piece in setting up SSL is to have Apache proxy requests for the IRM server but do so securely. So the requests to Apache will be over HTTPS using a legitimate certificate, but we can also configure Apache to proxy these requests internally across to the IRM server using SSL with the self signed certificate we generated at the start of this article. To do this proxying we use the WebLogic Web Server plugin for Apache which you can download here from Oracle. Download the zip file and extract onto the server. The file extraction reveals a set of zip files, each one specific to a supported web server. In my instance I am using Apache 2.2 32bit on an Oracle Enterprise Linux, 64 bit server. If you are not sure what version your Apache server is, run the command /usr/sbin/httpd -V and you'll see version and it its 32 or 64 bit. Mine is a 32bit server so I need to extract the file WLSPlugin1.1-Apache2.2-linux32-x86.zip. The from the resulting lib folder copy the file mod_wl.so into /usr/lib/httpd/modules/. First we want to test that the plug in will work for regular HTTP traffic. Edit the httpd.conf for Apache and add the following section at the bottom. LoadModule weblogic_module modules/mod_wl.so <IfModule mod_weblogic.c>    WebLogicHost irm.company.internal    WebLogicPort 16100    WLLogFile /tmp/wl-proxy.log </IfModule> <Location /irm_rights>    SetHandler weblogic-handler </Location> <Location /irm_desktop>    SetHandler weblogic-handler </Location> <Location /irm_sealing>    SetHandler weblogic-handler </Location> <Location /irm_services>    SetHandler weblogic-handler </Location> Now restart Apache again (apachectl restart) and now open a browser to http://irm.company.com/irm_rights. Apache will proxy the HTTP traffic from the port 80 of your Apache server to the IRM service listening on port 16100 of the WebLogic Managed server. Note above I have included all four of the Locations you might wish to proxy. http://irm.company.internalirm_rights is the URL to the management website, /irm_desktop is the URL used for the IRM Desktop to communicate. irm_sealing is for web services based document sealing and irm_services is for IRM server web services. The last two are typically only used when you have the IRM server integrated with another application and it is unlikely you'd be accessing these resources from the public facing Apache server. However, just in case, i've mentioned them above. Now let's enable SSL communication from Apache to WebLogic. In the ZIP file we extracted were some more modules we need to copy into the Apache folder. Looking back in the lib that we extracted, there are some more files. Copy the following into the /usr/lib/httpd/modules/ folder. libwlssl.so libnnz11.so libclntsh.so.11.1 Now the documentation states that should only need to do this, but I found that I also needed to create an environment variable called LD_LIBRARY_PATH and point this to the folder /usr/lib/httpd/modules/. If I didn't do this, starting Apache with the WebLogic module configured to SSL would throw the error. [crit] (20014)Internal error: WL SSL Init failed for server: (null) on 0 So I had to edit the file /etc/profile and add the following lines at the bottom. You may already have the LD_LIBRARY_PATH variable defined, therefore simply add this path to it. LD_LIBRARY_PATH=/usr/lib/httpd/modules/ export LD_LIBRARY_PATH Now the WebLogic plug in uses an Oracle Wallet to store the required certificates.You'll need to copy the self signed certificate from the IRM server over to the Apache server. Copy over the MyOwnSelfCA.cer.der into the same folder where you are storing your public certificates, in my example this is /oracle/secure. It's worth mentioning these files should ONLY be readable by root (the user Apache runs as). Now lets create an Oracle Wallet and import the self signed certificate from the IRM server. The file orapki was included in the bin folder of the Apache 1.1 plugin zip you extracted. orapki wallet create -wallet /oracle/secure/my-wallet -auto_login_only orapki wallet add -wallet /oracle/secure/my-wallet -trusted_cert -cert MyOwnSelfCA.cer.der -auto_login_only Finally change the httpd.conf to reflect that we want the WebLogic Apache plug-in to use HTTPS/SSL and not just plain HTTP. <IfModule mod_weblogic.c>    WebLogicHost irm.company.internal    WebLogicPort 16101    SecureProxy ON    WLSSLWallet /oracle/secure/my-wallet    WLLogFile /tmp/wl-proxy.log </IfModule> Then restart Apache once more and you can go back to the browser to test the communication. Opening the URL https://irm.company.com/irm_rights will proxy your request to the WebLogic server at https://irm.company.internal:16101/irm_rights. At this point you have a fully functional Oracle IRM service, the next step is to create a sealed document and test the entire system.

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  • Rotate sphere in Javascript / three.js while moving on x/z axes

    - by kaipr
    I have a sphere/ball in three.js which I want to "roll" arround on a x/z axis. For the z axe I could simply do this no matter what the current x and y rotation is: sphere.roll_z = function(distance) { sphere.position.z += distance; sphere.rotation.x += distance > 0 ? 0.05 : -0.05; } But how can I roll it along the x axe? And how could I properly do the roll_z? I've found a lot about quateration and matrixes, but I can't figure out how to use them properly to achieve my (rather simple) goal. I'm aware that I have to update multiple rotations and that I have to calculate how far to rotate the sphere to match the distance, but the "how" is the question. It's probably just lack of mathematical skills which I should train, but a working example/short explanation would help alot to start with.

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  • Subterranean IL: Volatile

    - by Simon Cooper
    This time, we'll be having a look at the volatile. prefix instruction, and one of the differences between volatile in IL and C#. The volatile. prefix volatile is a tricky one, as there's varying levels of documentation on it. From what I can see, it has two effects: It prevents caching of the load or store value; rather than reading or writing to a cached version of the memory location (say, the processor register or cache), it forces the value to be loaded or stored at the 'actual' memory location, so it is then immediately visible to other threads. It forces a memory barrier at the prefixed instruction. This ensures instructions don't get re-ordered around the volatile instruction. This is slightly more complicated than it first seems, and only seems to matter on certain architectures. For more details, Joe Duffy has a blog post going into the details. For this post, I'll be concentrating on the first aspect of volatile. Caching field accesses To demonstrate this, I created a simple multithreaded IL program. It boils down to the following code: .class public Holder { .field public static class Holder holder .field public bool stop .method public static specialname void .cctor() { newobj instance void Holder::.ctor() stsfld class Holder Holder::holder ret }}.method private static void Main() { .entrypoint // Thread t = new Thread(new ThreadStart(DoWork)) // t.Start() // Thread.Sleep(2000) // Console.WriteLine("Stopping thread...") ldsfld class Holder Holder::holder ldc.i4.1 stfld bool Holder::stop call instance void [mscorlib]System.Threading.Thread::Join() ret}.method private static void DoWork() { ldsfld class Holder Holder::holder // while (!Holder.holder.stop) {} DoWork: dup ldfld bool Holder::stop brfalse DoWork pop ret} If you compile and run this code, you'll find that the call to Thread.Join() never returns - the DoWork spinlock is reading a cached version of Holder.stop, which is never being updated with the new value set by the Main method. Adding volatile to the ldfld fixes this: dupvolatile.ldfld bool Holder::stopbrfalse DoWork The volatile ldfld forces the field access to read direct from heap memory, which is then updated by the main thread, rather than using a cached copy. volatile in C# This highlights one of the differences between IL and C#. In IL, volatile only applies to the prefixed instruction, whereas in C#, volatile is specified on a field to indicate that all accesses to that field should be volatile (interestingly, there's no mention of the 'no caching' aspect of volatile in the C# spec; it only focuses on the memory barrier aspect). Furthermore, this information needs to be stored within the assembly somehow, as such a field might be accessed directly from outside the assembly, but there's no concept of a 'volatile field' in IL! How this information is stored with the field will be the subject of my next post.

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  • Subterranean IL: The ThreadLocal type

    - by Simon Cooper
    I came across ThreadLocal<T> while I was researching ConcurrentBag. To look at it, it doesn't really make much sense. What's all those extra Cn classes doing in there? Why is there a GenericHolder<T,U,V,W> class? What's going on? However, digging deeper, it's a rather ingenious solution to a tricky problem. Thread statics Declaring that a variable is thread static, that is, values assigned and read from the field is specific to the thread doing the reading, is quite easy in .NET: [ThreadStatic] private static string s_ThreadStaticField; ThreadStaticAttribute is not a pseudo-custom attribute; it is compiled as a normal attribute, but the CLR has in-built magic, activated by that attribute, to redirect accesses to the field based on the executing thread's identity. TheadStaticAttribute provides a simple solution when you want to use a single field as thread-static. What if you want to create an arbitary number of thread static variables at runtime? Thread-static fields can only be declared, and are fixed, at compile time. Prior to .NET 4, you only had one solution - thread local data slots. This is a lesser-known function of Thread that has existed since .NET 1.1: LocalDataStoreSlot threadSlot = Thread.AllocateNamedDataSlot("slot1"); string value = "foo"; Thread.SetData(threadSlot, value); string gettedValue = (string)Thread.GetData(threadSlot); Each instance of LocalStoreDataSlot mediates access to a single slot, and each slot acts like a separate thread-static field. As you can see, using thread data slots is quite cumbersome. You need to keep track of LocalDataStoreSlot objects, it's not obvious how instances of LocalDataStoreSlot correspond to individual thread-static variables, and it's not type safe. It's also relatively slow and complicated; the internal implementation consists of a whole series of classes hanging off a single thread-static field in Thread itself, using various arrays, lists, and locks for synchronization. ThreadLocal<T> is far simpler and easier to use. ThreadLocal ThreadLocal provides an abstraction around thread-static fields that allows it to be used just like any other class; it can be used as a replacement for a thread-static field, it can be used in a List<ThreadLocal<T>>, you can create as many as you need at runtime. So what does it do? It can't just have an instance-specific thread-static field, because thread-static fields have to be declared as static, and so shared between all instances of the declaring type. There's something else going on here. The values stored in instances of ThreadLocal<T> are stored in instantiations of the GenericHolder<T,U,V,W> class, which contains a single ThreadStatic field (s_value) to store the actual value. This class is then instantiated with various combinations of the Cn types for generic arguments. In .NET, each separate instantiation of a generic type has its own static state. For example, GenericHolder<int,C0,C1,C2> has a completely separate s_value field to GenericHolder<int,C1,C14,C1>. This feature is (ab)used by ThreadLocal to emulate instance thread-static fields. Every time an instance of ThreadLocal is constructed, it is assigned a unique number from the static s_currentTypeId field using Interlocked.Increment, in the FindNextTypeIndex method. The hexadecimal representation of that number then defines the specific Cn types that instantiates the GenericHolder class. That instantiation is therefore 'owned' by that instance of ThreadLocal. This gives each instance of ThreadLocal its own ThreadStatic field through a specific unique instantiation of the GenericHolder class. Although GenericHolder has four type variables, the first one is always instantiated to the type stored in the ThreadLocal<T>. This gives three free type variables, each of which can be instantiated to one of 16 types (C0 to C15). This puts an upper limit of 4096 (163) on the number of ThreadLocal<T> instances that can be created for each value of T. That is, there can be a maximum of 4096 instances of ThreadLocal<string>, and separately a maximum of 4096 instances of ThreadLocal<object>, etc. However, there is an upper limit of 16384 enforced on the total number of ThreadLocal instances in the AppDomain. This is to stop too much memory being used by thousands of instantiations of GenericHolder<T,U,V,W>, as once a type is loaded into an AppDomain it cannot be unloaded, and will continue to sit there taking up memory until the AppDomain is unloaded. The total number of ThreadLocal instances created is tracked by the ThreadLocalGlobalCounter class. So what happens when either limit is reached? Firstly, to try and stop this limit being reached, it recycles GenericHolder type indexes of ThreadLocal instances that get disposed using the s_availableIndices concurrent stack. This allows GenericHolder instantiations of disposed ThreadLocal instances to be re-used. But if there aren't any available instantiations, then ThreadLocal falls back on a standard thread local slot using TLSHolder. This makes it very important to dispose of your ThreadLocal instances if you'll be using lots of them, so the type instantiations can be recycled. The previous way of creating arbitary thread-static variables, thread data slots, was slow, clunky, and hard to use. In comparison, ThreadLocal can be used just like any other type, and each instance appears from the outside to be a non-static thread-static variable. It does this by using the CLR type system to assign each instance of ThreadLocal its own instantiated type containing a thread-static field, and so delegating a lot of the bookkeeping that thread data slots had to do to the CLR type system itself! That's a very clever use of the CLR type system.

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  • Normal map lighting bug in bottom right quadrant

    - by Ryan Capote
    I am currently working on getting normal maps working in my project, and have run into a problem with lighting. As you can see, the normals in the bottom right quadrant of the lighting isn't calculating the correct direction to the light or something. Best seen by the red light If I use flat normals (z normal = 1.0), it seems to be working fine: normals for the tile sheet: Shader: #version 330 uniform sampler2D uDiffuseTexture; uniform sampler2D uNormalsTexture; uniform sampler2D uSpecularTexture; uniform sampler2D uEmissiveTexture; uniform sampler2D uWorldNormals; uniform sampler2D uShadowMap; uniform vec4 uLightColor; uniform float uConstAtten; uniform float uLinearAtten; uniform float uQuadradicAtten; uniform float uColorIntensity; in vec2 TexCoords; in vec2 GeomSize; out vec4 FragColor; float sample(vec2 coord, float r) { return step(r, texture2D(uShadowMap, coord).r); } float occluded() { float PI = 3.14; vec2 normalized = TexCoords.st * 2.0 - 1.0; float theta = atan(normalized.y, normalized.x); float r = length(normalized); float coord = (theta + PI) / (2.0 * PI); vec2 tc = vec2(coord, 0.0); float center = sample(tc, r); float sum = 0.0; float blur = (1.0 / GeomSize.x) * smoothstep(0.0, 1.0, r); sum += sample(vec2(tc.x - 4.0*blur, tc.y), r) * 0.05; sum += sample(vec2(tc.x - 3.0*blur, tc.y), r) * 0.09; sum += sample(vec2(tc.x - 2.0*blur, tc.y), r) * 0.12; sum += sample(vec2(tc.x - 1.0*blur, tc.y), r) * 0.15; sum += center * 0.16; sum += sample(vec2(tc.x + 1.0*blur, tc.y), r) * 0.15; sum += sample(vec2(tc.x + 2.0*blur, tc.y), r) * 0.12; sum += sample(vec2(tc.x + 3.0*blur, tc.y), r) * 0.09; sum += sample(vec2(tc.x + 4.0*blur, tc.y), r) * 0.05; return sum * smoothstep(1.0, 0.0, r); } float calcAttenuation(float distance) { float linearAtten = uLinearAtten * distance; float quadAtten = uQuadradicAtten * distance * distance; float attenuation = 1.0 / (uConstAtten + linearAtten + quadAtten); return attenuation; } vec3 calcFragPosition(void) { return vec3(TexCoords*GeomSize, 0.0); } vec3 calcLightPosition(void) { return vec3(GeomSize/2.0, 0.0); } float calcDistance(vec3 fragPos, vec3 lightPos) { return length(fragPos - lightPos); } vec3 calcLightDirection(vec3 fragPos, vec3 lightPos) { return normalize(lightPos - fragPos); } vec4 calcFinalLight(vec2 worldUV, vec3 lightDir, float attenuation) { float diffuseFactor = dot(normalize(texture2D(uNormalsTexture, worldUV).rgb), lightDir); vec4 diffuse = vec4(0.0); vec4 lightColor = uLightColor * uColorIntensity; if(diffuseFactor > 0.0) { diffuse = vec4(texture2D(uDiffuseTexture, worldUV.xy).rgb, 1.0); diffuse *= diffuseFactor; lightColor *= diffuseFactor; } else { discard; } vec4 final = (diffuse + lightColor); if(texture2D(uWorldNormals, worldUV).g > 0.0) { return final * attenuation; } else { return final * occluded(); } } void main(void) { vec3 fragPosition = calcFragPosition(); vec3 lightPosition = calcLightPosition(); float distance = calcDistance(fragPosition, lightPosition); float attenuation = calcAttenuation(distance); vec2 worldPos = gl_FragCoord.xy / vec2(1024, 768); vec3 lightDir = calcLightDirection(fragPosition, lightPosition); lightDir = (lightDir*0.5)+0.5; float atten = calcAttenuation(distance); vec4 emissive = texture2D(uEmissiveTexture, worldPos); FragColor = calcFinalLight(worldPos, lightDir, atten) + emissive; }

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  • Detecting walls or floors in pygame

    - by Serial
    I am trying to make bullets bounce of walls, but I can't figure out how to correctly do the collision detection. What I am currently doing is iterating through all the solid blocks and if the bullet hits the bottom, top or sides, its vector is adjusted accordingly. However, sometimes when I shoot, the bullet doesn't bounce, I think it's when I shoot at a border between two blocks. Here is the update method for my Bullet class: def update(self, dt): if self.can_bounce: #if the bullet hasnt bounced find its vector using the mousclick pos and player pos speed = -10. range = 200 distance = [self.mouse_x - self.player[0], self.mouse_y - self.player[1]] norm = math.sqrt(distance[0] ** 2 + distance[1] ** 2) direction = [distance[0] / norm, distance[1 ] / norm] bullet_vector = [direction[0] * speed, direction[1] * speed] self.dx = bullet_vector[0] self.dy = bullet_vector[1] #check each block for collision for block in self.game.solid_blocks: last = self.rect.copy() if self.rect.colliderect(block): topcheck = self.rect.top < block.rect.bottom and self.rect.top > block.rect.top bottomcheck = self.rect.bottom > block.rect.top and self.rect.bottom < block.rect.bottom rightcheck = self.rect.right > block.rect.left and self.rect.right < block.rect.right leftcheck = self.rect.left < block.rect.right and self.rect.left > block.rect.left each test tests if it hit the top bottom left or right side of the block its colliding with if self.can_bounce: if topcheck: self.rect = last self.dy *= -1 self.can_bounce = False print "top" if bottomcheck: self.rect = last self.dy *= -1 #Bottom check self.can_bounce = False print "bottom" if rightcheck: self.rect = last self.dx *= -1 #right check self.can_bounce = False print "right" if leftcheck: self.rect = last self.dx *= -1 #left check self.can_bounce = False print "left" else: # if it has already bounced and colliding again kill it self.kill() for enemy in self.game.enemies_list: if self.rect.colliderect(enemy): self.kill() #update position self.rect.x -= self.dx self.rect.y -= self.dy This definitely isn't the best way to do it but I can't think of another way. If anyone has done this or can help that would be awesome!

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  • Delete blank row in dropdownlist or select default value in infopath dropdown

    - by KunaalKapoor
    Regular Dropdown (Pulling from DataSource)1. Double click on dropdown field in the data source.2. Select Fx button for Default value.3. Select Insert field or group.4. Select secondary xml from data source.5. Select “value” and click on ok.For a cascading dropdown:You have to add the rule and follow these steps,1. Rules -> ‘Add’ - > ‘Add Action’.2. Select ‘Set a field value’ option in first dropdown in Action.3. Select your field with help of ‘Select a Field or Group’ option in ‘Field’.4. Select your external data source list value in ‘Value’.This rule you can apply in OnLoad or whenever you will get external data source values.

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  • Save Zone Implementation in Asteroids

    - by Moaz
    I would like to implement a safe zone for asteroids so that when the ship gets destroyed, it shouldn't be there unless it is safe from other asteroids. I tried to check the distance between each asteroid and the ship, and if it is above threshold, it sets a flag to the ship that's a safe zone, but sometimes it work and sometimes it doesn't for (list<Asteroid>::iterator itr_astroid = asteroids.begin(); itr_astroid!=asteroids.end(); ) { if(currentShip.m_state == Ship::Ship_Dead) { float distance = itr_astroid->getCenter().distance(Vec2f(getWindowWidth()/2,getWindowHeight()/2)); if( distance>200) { currentShip.m_saveField = true; break; } else { currentShip.m_saveField = false; itr_astroid++; } } else { itr_astroid++; } }

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  • Restrict movement within a radius

    - by Phil
    I asked a similar question recently but now I think I know more about what I really want to know. I can answer my own question if I get to understand this bit. I have a situation where a sprite's center point needs to be constrained within a certain boundary in 2d space. The boundary is circular so the sprite is constrained within a radius. This radius is defined as a distance from the center of a certain point. I know the position of the center point and I can track the center position of the sprite. This is the code to detect the distance: float distance = Vector2.Distance(centerPosition, spritePosition)); if (distance > allowedDistance) { } The positions can be wherever on the grid, they are not described as in between -1 or 1. So basically the detecting code works, it only prints when the sprite is outside of it's boundary I just don't know what to do when it oversteps. Please explain any math used as I really want to understand what you're thinking to be able to elaborate on it myself.

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  • Recognizing text fields according to their label value

    - by Pierpaolo Bagnasco
    I have an application who has text fields (not select, not checkbox or other types) where an user can enter some value, like this: ISBN and E-Mail are the label of each input. Now I have to automatically test these inputs according to their label. The question is: how to recognize that, for example, the first input requires an ISBN code? I programmed something like this: turn the label value to lowercase check if the label value contains isbn if so set the field value to a random ISBN code (i.e.: 1234567890), else set it to a random value (default) For the email field: turn the label value to lowercase check if the label value contains e-mail or email or mail if so set the field value to a random email (i.e.: [email protected]), else set it to a random value (default) And so on for each text field I encounter. Is that reliable? How can I improve the "recognizing part"? I know only the label value and the field value (what is already written in the field by default) for each text input.

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  • How to use Excel VBA to extract Memo field from Access Database?

    - by the.jxc
    I have an Excel spreadsheet. I am connecting to an Access database via ODBC. Something along then lines of: Set dbEng = CreateObject("DAO.DBEngine.40") Set oWspc = dbEng.CreateWorkspace("ODBCWspc", "", "", dbUseODBC) Set oConn = oWspc.OpenConnection("Connection", , True, "ODBC;DSN=CLIENTDB;") Then I use a query and fetch a result set to get some table data. Set oQuery = oConn.CreateQueryDef("tmpQuery") oQuery.Sql = "SELECT idField, memoField FROM myTable" Set oRs = oQuery.OpenRecordset The problem now arises. My field is a dbMemo because the maximum content length is up to a few hundred chars. It's not that long, and in fact the value I'm reading is only a dozen characters. But Excel just doesn't seem able to handle the Memo field content at all. My code... ActiveCell = oRs.Fields("memoField") ...gives error Run-time error '3146': ODBC--call failed. Any suggestions? Can Excel VBA actually get at memo field data? Or is it just completely impossible. I get exactly the same error from GetChunk as well. ActiveCell = oRs.Fields("memoField").GetChunk(0, 2) ...also gives error Run-time error '3146': ODBC--call failed. Converting to a text field makes everything work fine. However some data is truncated to 255 characters of course, which means that isn't a workable solution.

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  • How to make a mapped field inherited from a superclass transient in JPA?

    - by Russ Hayward
    I have a legacy schema that cannot be changed. I am using a base class for the common features and it contains an embedded object. There is a field that is normally mapped in the embedded object that needs to be in the persistence id for only one (of many) subclasses. I have made a new id class that includes it but then I get the error that the field is mapped twice. Here is some example code that is much simplified to maintain the sanity of the reader: @MappedSuperclass class BaseClass { @Embedded private Data data; } @Entity class SubClass extends BaseClass { @EmbeddedId private SubClassId id; } @Embeddable class Data { private int location; private String name; } @Embeddable class SubClassId { private int thingy; private int location; } I have tried @AttributeOverride but I can only get it to rename the field. I have tried to set it to updatable = false, insertable = false but this did not seem to work when used in the @AttributeOverride annotation. See answer below for the solution to this issue. I realise I could change the base class but I really do not want to split up the embedded object to separate the shared field as it would make the surrounding code more complex and require some ugly wrapping code. I could also redesign the whole system for this corner case but I would really rather not. I am using Hibernate as my JPA provider.

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  • How do I remove unnecessary options from a select field in a Drupal form?

    - by thismax
    I'm using the better_exposed_filters module to create a set of exposed filters for a view. One of the filters is being displayed as a select field, and I would like the field to only display options that are actually associated with content in the database. Currently, I am doing this using the hook_form_alter() method. For simplification, in the following example the field is called 'foo' and the content type with that field is called 'bar': function my_module_form_alter(&$form, $form_state, $form_id) { // Get all the values of foo that matter $resource = db_query('select distinct field_foo_value from {content_type_bar}'); $foo = array(); while($row = db_fetch_object($resource)) { $foo[$row->field_foo_value] = $row->field_foo_value; } $form['foo']['#options'] = $manufacturers; } This works great -- the form displays only the options I want to display. Unfortunately, the view doesn't actually display anything initially and I also get the following error message: An illegal choice has been detected. Please contact the site administrator. After I filter options with the form once, everything seems to work fine. Does anyone know how I can solve this problem? I'm open to an entirely different way of weeding out filter options, if need be, or a way that I can figure out how to address that error.

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  • Where is the read/unread field in Outlook 2010 custom search?

    - by Ken
    I am trying to create a custom search folder in outlook 2010. I am using the "advanced" tab in the "search folder criteria" dialog. One of the criteria I need is the read/unread status of an message. But the "field" dropdown does not contain a field corresponding to read/unread status (see screen shot below). This is odd because the read/unread status is available in the "More Choices" tab, but seemingly not in the "advanced" tab. How do I create an advanced search folder criteria which incorporates the read/unread status of a message?

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  • How can I make the Outlook "To" field allow auto completion for all my contacts?

    - by Space Cracker
    When we make a new mail message in Outlook 2007 and try to write any letter in To field it shows an auto complete list with all available contacts that contain written letters. This list is displaying all emails that you have send to them before and over time this list grows as you send to more and more new contacts... My Issues: When we reinstall Windows, install new copy of Outlook, create a new mail message, try to write any character in To field it will not show any contacts and this leads to write it or choose from contacts. Is it in any way possible to make Outlook's contacts, or specific contacts I determine to be cached, appear in TO when I write any letter without need to write them again?

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  • How i can make Outlook To field to allow auto complete for all my contacts ?

    - by Space Cracker
    When we make new mail message in outlook 2007 and try to write any letter in To field it show auto complete list with all available contacts that contain written letters. This list is appear with all emails that u send to them before and over time this list be more and more with new contacts you send to ... My Issues : When we reinstall windows ,install new copy of outlook,create new mail message ,try yo write any character in To field it will not show any contacts and this lead to write it or choose from contacts ... Is it any way to make outlook add my contacts or specific contacts I determined to be cached and appear in TOwhen i write any letter without need to write them again ?

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  • deepcopy and python - tips to avoid using it?

    - by blackkettle
    Hi, I have a very simple python routine that involves cycling through a list of roughly 20,000 latitude,longitude coordinates and calculating the distance of each point to a reference point. def compute_nearest_points( lat, lon, nPoints=5 ): """Find the nearest N points, given the input coordinates.""" points = session.query(PointIndex).all() oldNearest = [] newNearest = [] for n in xrange(nPoints): oldNearest.append(PointDistance(None,None,None,99999.0,99999.0)) newNearest.append(obj2) #This is almost certainly an inappropriate use of deepcopy # but how SHOULD I be doing this?!?! for point in points: distance = compute_spherical_law_of_cosines( lat, lon, point.avg_lat, point.avg_lon ) k = 0 for p in oldNearest: if distance < p.distance: newNearest[k] = PointDistance( point.point, point.kana, point.english, point.avg_lat, point.avg_lon, distance=distance ) break else: newNearest[k] = deepcopy(oldNearest[k]) k += 1 for j in range(k,nPoints-1): newNearest[j+1] = deepcopy(oldNearest[j]) oldNearest = deepcopy(newNearest) #We're done, now print the result for point in oldNearest: print point.station, point.english, point.distance return I initially wrote this in C, using the exact same approach, and it works fine there, and is basically instantaneous for nPoints<=100. So I decided to port it to python because I wanted to use SqlAlchemy to do some other stuff. I first ported it without the deepcopy statements that now pepper the method, and this caused the results to be 'odd', or partially incorrect, because some of the points were just getting copied as references(I guess? I think?) -- but it was still pretty nearly as fast as the C version. Now with the deepcopy calls added, the routine does it's job correctly, but it has incurred an extreme performance penalty, and now takes several seconds to do the same job. This seems like a pretty common job, but I'm clearly not doing it the pythonic way. How should I be doing this so that I still get the correct results but don't have to include deepcopy everywhere?

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  • How does the last integer promotion rule ever get applied in C?

    - by SiegeX
    6.3.1.8p1: Otherwise, the integer promotions are performed on both operands. Then the following rules are applied to the promoted operands: If both operands have the same type, then no further conversion is needed. Otherwise, if both operands have signed integer types or both have unsigned integer types, the operand with the type of lesser integer conversion rank is converted to the type of the operand with greater rank. Otherwise, if the operand that has unsigned integer type has rank greater or equal to the rank of the type of the other operand, then the operand with signed integer type is converted to the type of the operand with unsigned integer type. Otherwise, if the type of the operand with signed integer type can represent all of the values of the type of the operand with unsigned integer type, then the operand with unsigned integer type is converted to the type of the operand with signed integer type. Otherwise, both operands are converted to the unsigned integer type corresponding to the type of the operand with signed integer type. For the bolded rule to be applied it would seem to imply you need to have have an unsigned interger type who's rank is less than the signed integer type and the signed integer type cannot hold all the values of the unsigned integer type. Is there a real world example of such a case or is this statement serving as a catch-all to cover all possible permutations?

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  • Ordering by formula fields in NHibernate

    - by Darin Dimitrov
    Suppose that I have the following mapping with a formula property: <class name="Planet" table="planets"> <id name="Id" column="id"> <generator class="native" /> </id> <!-- somefunc() is a native SQL function --> <property name="Distance" formula="somefunc()" /> </class> I would like to get all planets and order them by the Distance calculated property: var planets = session .CreateCriteria<Planet>() .AddOrder(Order.Asc("Distance")) .List<Planet>(); This is translated to the following query: SELECT Id as id0, somefunc() as formula0 FROM planets ORDER BY somefunc() Desired query: SELECT Id as id0, somefunc() as formula0 FROM planets ORDER BY formula0 If I set a projection with an alias it works fine: var planets = session .CreateCriteria<Planet>() .SetProjection(Projections.Alias(Projections.Property("Distance"), "dist")) .AddOrder(Order.Asc("dist")) .List<Planet>(); SQL: SELECT somefunc() as formula0 FROM planets ORDER BY formula0 but it populates only the Distance property in the result and I really like to avoid projecting manually over all the other properties of my object (there could be many other properties). Is this achievable with NHibernate? As a bonus I would like to pass parameters to the native somefunc() SQL function. Anything producing the desired SQL is acceptable (replacing the formula field with subselects, etc...), the important thing is to have the calculated Distance property in the resulting object and order by this distance inside SQL.

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  • How to putExtra() in Searchable Dictionary Example

    - by sirlunchalot
    Hi, based on the Searchable Dictionary sample I tried to put extra data to a different activity. public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Spinner distance = (Spinner) findViewById(R.id.distanceSpinner); ArrayAdapter<CharSequence> adapterDistance = ArrayAdapter.createFromResource( this, R.array.distance, android.R.layout.simple_spinner_item); adapterDistance.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); distance.setAdapter(adapterDistance); Intent intent = getIntent(); if (Intent.ACTION_VIEW.equals(intent.getAction())) { // handles a click on a search suggestion; launches activity to show word mapIntent = new Intent(this, Map.class); mapIntent.setData(intent.getData()); mapIntent.putExtra("Distance", distance.getSelectedItemPosition()); startActivity(mapIntent); finish(); } } In my Map Class Distance is always zero because distance.getSelectedItemPostion() gets the initialized value. How can I putExtra data with a click on a search suggestion? Thanks

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  • How to change the font color of blackberry label field dynamically?

    - by Kumar
    I have one label field and three buttons with the name of red, yellow, blue. If I click the red button then the label field font color should be change to red; similarly if I click the yellow button then the font color should change to yellow; likewise according to the button color the color of font should change in the label field. Can anyone tell me how to do this? If you can, provide me some code snippet. Regards, S.Kumaran.

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