net.logstash.logback.util

Class ThreadLocalHolder<T>

java.lang.Object

net.logstash.logback.util.ThreadLocalHolder<T>

Type Parameters:

T - type of instances returned by this ThreadLocalHolder.

Direct Known Subclasses:

ThreadLocalReusableByteBuffer

public class ThreadLocalHolder<T>
extends Object

Maintains a per-thread value created by the Supplier given to the constructor.

A thread obtains the value by calling acquire() and must release it after use by calling release(). If the value is not released, subsequent calls to acquire() will throw an IllegalStateException.

Instances value may also implement the optional ThreadLocalHolder.Lifecycle interface if they wish to be notified when they are recycled or disposed.

The holder keeps track of each requesting thread and takes care of disposing the allocated value when it dies. All allocated values are automatically disposed when close() is called.

Note: This class is for internal use only and subject to backward incompatible change at any time.

Author:

brenuart

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	ThreadLocalHolder.HolderRef A WeakReference to a thread with the Holder assigned to it.
static interface	ThreadLocalHolder.Lifecycle Optional interface that pooled instances may implement if they wish to be notified of life cycle events.

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<Long,ThreadLocalHolder.HolderRef>	threadValues Collection of values assigned to each thread

Constructor Summary

Constructors

Constructor and Description
ThreadLocalHolder(Supplier<T> factory) Create a new instance of the pool.

Method Summary

Modifier and Type	Method and Description
T	acquire() Get the value assigned to the current thread, creating a new one if none is assigned yet or the previous has been disposed.
void	close() Close the holder and dispose all values.
protected T	createInstance() Create a new object instance (must be non-null).
protected void	disposeInstance(T instance) Dispose the object instance by calling its life cycle methods.
protected boolean	recycleInstance(T instance) Recycle the instance before returning it to the pool.
void	release() Release the value and recycle it if possible.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

threadValues

protected final Map<Long,ThreadLocalHolder.HolderRef> threadValues

Collection of values assigned to each thread

Constructor Detail

ThreadLocalHolder

public ThreadLocalHolder(Supplier<T> factory)

Create a new instance of the pool.

Parameters:

factory - the factory used to create new instances.

Method Detail

acquire

public final T acquire()

Get the value assigned to the current thread, creating a new one if none is assigned yet or the previous has been disposed. The value must be release() to ensure proper life cycle before it can be acquire() again.

Returns:

the value assigned to this thread

Throws:

IllegalStateException - if the value is already in use and release() was not yet invoked.

release

public final void release()

Release the value and recycle it if possible.

Throws:

IllegalStateException - if the value was not previously acquire().

close

public void close()

Close the holder and dispose all values. Threads are still able to acquire() values after the holder is closed, but they will be disposed immediately when release() instead of recycled.

createInstance

protected T createInstance()

Create a new object instance (must be non-null). Sub-classes may override this method to implement their own custom logic if needed.

Returns:

a new object instance

disposeInstance

protected void disposeInstance(T instance)

Dispose the object instance by calling its life cycle methods. Sub-classes may override this method if they wish to implement their own custom logic.

Parameters:

instance - the instance to dispose

recycleInstance

protected boolean recycleInstance(T instance)

Recycle the instance before returning it to the pool. Sub-classes may override this method if they wish to implement their own custom logic.

Parameters:

instance - the instance to recycle

Returns:

true if the instance can be recycled and returned to the pool, false if not.