Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>It should be possible to create a thread-safe version of "A", if this object is <a href="http://en.wikipedia.org/wiki/Loose_coupling" rel="nofollow">loosely coupled</a> with all its clients. </p> <p>An example directly from the JDK:</p> <pre><code>java.lang.Appendable - the interface java.lang.StringBuilder - regular implementation java.lang.StringBuffer - thread-safe implementation </code></pre> <p>The client doesn't have to know, if it's a thread-safe version, since it's using the object indirectly, through an interface:</p> <pre><code>void doSomething(Appendable a) { a.append(...); } </code></pre> <p>From a practical standpoint, using <a href="http://en.wikipedia.org/wiki/Inversion_of_control" rel="nofollow">inversion of control</a> can significantly help. Use interfaces for business contract declaration and Spring (or any other dependency injection framework) for component injection (whether it's thread-safe or not depends on the configuration only).</p> <p><strong>Bottom line:</strong> you can prevent such problems with <strong>loose coupling</strong> and smart architecture design (separation of concerns etc.).</p>
    singulars
    1. This table or related slice is empty.
    1. POMultiple threads in application - design convention?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USSzymon Biliński
    1. USSzymon Biliński
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COTo be honest I am not sure which of these two answers yours or Chris to accept. Because I know we could create some interface which marks that class's object is accessed from many threads,etc., but this is a bit redundant. Appendable interface has nothing to do with threads. And how do you know that StringBuffer is thread safe? Because you can read it in javadoc. But in a project it can be a bit tricky. I am not sure if all developers read all javadoc updates. But I think javadoc seems to be really good place to describe behaviour and it doesn't complicate implementation. hmmm... :)
      singulars
      1. PO
      1. USŁukasz Rzeszotarski
    2. COMy point is: you shouldn't expose concurrency outside the component. Appendable doesn't "mark" your class as thread-safe. It is a business contract, that states: you can append a CharSequence to this "thing". Nothing more. If you need, a thread-safe implementation, then you will instantiate a StringBuffer. Otherwise, it would be more efficient to use a StringBuilder. The client doesn't have to know about the synchronization mechanisms, that are used internally to protect the state. Same thing applies to the service "world" (take EJBs for an example).
      singulars
      1. PO
      1. USSzymon Biliński
    3. COOn another note: "updating javadocs" on an existing component doesn't really affect any real life situations. It's just like saying "it's not my business, the client should adapt and I don't really care - read the CHANGELOG, if you get into any problems". Also, unit tests won't help you much in this case, since reliable testing of concurrency can be really tricky (detecting deadlocks and process starvation for example).
      singulars
      1. PO
      1. USSzymon Biliński
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload