javolution.context.AbstractContext Class Reference

Inheritance diagram for javolution.context.AbstractContext:

Collaboration diagram for javolution.context.AbstractContext:

Public Member Functions
void	exit ()

Static Public Member Functions
static AbstractContext	current ()
static< T extends AbstractContext > T	enter (Class< T > custom)
static void	inherit (AbstractContext ctx)

Protected Member Functions
	AbstractContext ()
AbstractContext	enterInner ()
AbstractContext	getOuter ()
abstract AbstractContext	inner ()

Static Protected Member Functions
static< T extends AbstractContext > T	current (Class< T > type)

Private Attributes
AbstractContext	outer

Static Private Attributes
static final ThreadLocal< AbstractContext >	CURRENT = new ThreadLocal<AbstractContext>()

Detailed Description

The parent class for all contexts. Contexts allow for cross cutting concerns (performance, logging, security, ...) to be addressed at run-time through OSGi published services without polluting the application code (Separation of Concerns).

Context configuration is performed in a

try, finally 

block statement and impacts only the current thread (although inherited by inner ConcurrentContext threads). [code] AnyContext ctx = AnyContext.enter(); // Enters a context scope. try {
ctx.configure(...); // Local configuration (optional). ... // Current thread executes using the configured context. } finally { ctx.exit(); }[/code]

Author

Jean-Marie Dautelle

Version

6.0, July 21, 2013

Definition at line 40 of file AbstractContext.java.

Constructor & Destructor Documentation

AbstractContext()

javolution.context.AbstractContext.AbstractContext ( )

protected

Default constructor.

Definition at line 55 of file AbstractContext.java.

{}

Member Function Documentation

current() [1/2]

static AbstractContext javolution.context.AbstractContext.current ( )

static

Returns the current context for the current thread or

null 

if this thread has no context (default).

Definition at line 61 of file AbstractContext.java.

                                            {
        return AbstractContext.CURRENT.get();
    }

References javolution.context.AbstractContext.CURRENT.

Referenced by javolution.context.LogContext.currentLogContext(), javolution.context.SecurityContext.currentSecurityContext(), javolution.text.TextContext.currentTextContext(), javolution.xml.XMLContext.currentXMLContext(), javolution.context.LocalContext.enter(), javolution.context.ConcurrentContext.enter(), and javolution.context.LocalContext.Parameter< T >.get().

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current() [2/2]

static <T extends AbstractContext> T javolution.context.AbstractContext.current ( Class< T >  type )

staticprotected

Returns the current context of specified type or

null 

if none.

Definition at line 69 of file AbstractContext.java.

                                                                          {
        AbstractContext ctx = AbstractContext.CURRENT.get();
        while (ctx != null) {
            if (type.isInstance(ctx))
                return (T) ctx;
            ctx = ctx.outer;
        }
        return null;
    }

References javolution.context.AbstractContext.CURRENT, and javolution.context.AbstractContext.outer.

enter()

static <T extends AbstractContext> T javolution.context.AbstractContext.enter ( Class< T >  custom )

static

Enters the scope of a custom context. This method raises a SecurityException if the permission to enter contexts of the specified class is not granted. For example, the following disallow entering any custom context. [code] SecurityContext ctx = SecurityContext.enter(); try { ctx.revoke(new SecurityContext.Permission(AbstractContext.class, "enter")); ... // Cannot enter any custom context. } finally { ctx.exit(); // Back to previous security settings. }[/code]

Parameters

custom

the custom context to enter.

Exceptions

IllegalArgumentException	if the specified class default constructor cannot be instantiated.
SecurityException	if SecurityContext.Permission(custom, "enter") is not granted.

See also

SecurityContext.Permission

Definition at line 101 of file AbstractContext.java.

                                                                       {
        SecurityContext.check(new Permission<T>(custom, "enter"));
        try {
            return (T) custom.newInstance().enterInner();
        } catch (InstantiationException e) {
            throw new IllegalArgumentException(
                    "Cannot instantiate instance of " + custom, e);
        } catch (IllegalAccessException e) {
            throw new IllegalArgumentException("Cannot access " + custom, e);
        }
    }

References javolution.context.SecurityContext.check().

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enterInner()

AbstractContext javolution.context.AbstractContext.enterInner ( )

protected

Enters the scope of an inner context which becomes the current context; the previous current context becomes the outer of this context.

Returns

the inner context entered.

Definition at line 141 of file AbstractContext.java.

                                           {
        AbstractContext inner = inner();
        inner.outer = AbstractContext.CURRENT.get();
        AbstractContext.CURRENT.set(inner);
        return inner;
    }

References javolution.context.AbstractContext.CURRENT, and javolution.context.AbstractContext.outer.

Referenced by javolution.xml.XMLContext.enter(), javolution.text.TextContext.enter(), javolution.context.LogContext.enter(), javolution.context.LocalContext.enter(), javolution.context.SecurityContext.enter(), and javolution.context.ConcurrentContext.enter().

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exit()

void javolution.context.AbstractContext.exit

(

)

Exits the scope of this context; the outer of this context becomes
the current context.

Exceptions

IllegalStateException

if this context is not the current context.

Reimplemented in javolution.context.ConcurrentContext, and javolution.context.internal.ConcurrentContextImpl.

Definition at line 155 of file AbstractContext.java.

                       {
        if (this != AbstractContext.CURRENT.get())
            throw new IllegalStateException(
                    "This context is not the current context");
        AbstractContext.CURRENT.set(outer);
        outer = null;
    }

References javolution.context.AbstractContext.CURRENT.

getOuter()

AbstractContext javolution.context.AbstractContext.getOuter ( )

protected

Returns the outer context of this context or

null 

if this context has no outer context.

Definition at line 167 of file AbstractContext.java.

                                         {
        return outer;
    }

inherit()

static void javolution.context.AbstractContext.inherit ( AbstractContext  ctx )

static

Inherits the specified context which becomes the context of the current thread. This method is particularly useful when creating new threads to make them inherits from the context stack of the parent thread. [code] //Spawns a new thread inheriting the context of the current thread. MyThread myThread = new MyThread(); myThread.inherited = AbstractContext.current(); myThread.start(); ... class MyThread extends Thread { AbstractContext inherited; public void run() { AbstractContext.inherit(inherited); // Sets current context. ... } }[/code]

Definition at line 131 of file AbstractContext.java.

                                                    {
        CURRENT.set(ctx);
    }

Referenced by javolution.context.internal.ConcurrentThreadImpl.run().

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inner()

abstract AbstractContext javolution.context.AbstractContext.inner ( )

abstractprotected

Returns a new inner instance of this context inheriting the properties of this context. The new instance can be configured independently from its parent.

Reimplemented in javolution.context.internal.ConcurrentContextImpl, javolution.text.internal.TextContextImpl, javolution.context.internal.LogContextImpl, javolution.context.internal.SecurityContextImpl, javolution.xml.internal.XMLContextImpl, and javolution.context.internal.LocalContextImpl.

Member Data Documentation

CURRENT

final ThreadLocal<AbstractContext> javolution.context.AbstractContext.CURRENT = new ThreadLocal<AbstractContext>()

staticprivate

Holds the last context entered (thread-local).

Definition at line 45 of file AbstractContext.java.

Referenced by javolution.context.AbstractContext.current(), javolution.context.AbstractContext.enterInner(), and javolution.context.AbstractContext.exit().

outer

AbstractContext javolution.context.AbstractContext.outer

private

Holds the outer context or

null 

if none (top context).

Definition at line 50 of file AbstractContext.java.

Referenced by javolution.context.AbstractContext.current(), and javolution.context.AbstractContext.enterInner().

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The documentation for this class was generated from the following file:

• AbstractContext.java