Package com.linkedin.alpini.base.misc

Class SoftThreadLocal<T>

java.lang.Object

com.linkedin.alpini.base.misc.SoftThreadLocal<T>

All Implemented Interfaces:

Supplier<T>

public class SoftThreadLocal<T>
extends Object
implements Supplier<T>

This class provides thread-local variables with SoftReference semantics.

Constructor Summary

Constructors

Constructor	Description
SoftThreadLocal()

Method Summary

Modifier and Type	Method	Description
T	get()	Returns the value in the current thread's copy of this thread-local variable.
protected T	initialValue()	Returns the current thread's "initial value" for this thread-local variable.
void	remove()	Removes the current thread's value for this thread-local variable.
void	set(T value)	Sets the current thread's copy of this thread-local variable to the specified value.
static <S> SoftThreadLocal<S>	withInitial(Supplier<? extends S> supplier)	Creates a thread local variable.

Methods inherited from class java.lang.Object

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

Constructor Details

SoftThreadLocal

public SoftThreadLocal()

Method Details

withInitial

@Nonnull
public static <S> SoftThreadLocal<S> withInitial(@Nonnull
 Supplier<? extends S> supplier)

Creates a thread local variable. The initial value of the variable is determined by invoking the get method on the Supplier.

Type Parameters:

S - the type of the thread local's value

Parameters:

supplier - the supplier to be used to determine the initial value

Returns:

a new thread local variable

Throws:

NullPointerException - if the specified supplier is null

Since:

1.8

initialValue

protected T initialValue()

Returns the current thread's "initial value" for this thread-local variable. This method will be invoked the first time a thread accesses the variable with the get() method, unless the thread previously invoked the set(T) method, in which case the initialValue method will not be invoked for the thread. Normally, this method is invoked at most once per thread, but it may be invoked again in case of subsequent invocations of remove() followed by get().

This implementation simply returns null; if the programmer desires thread-local variables to have an initial value other than null, ThreadLocal must be subclassed, and this method overridden. Typically, an anonymous inner class will be used.

Returns:

the initial value for this thread-local

get

public T get()

Returns the value in the current thread's copy of this thread-local variable. If the variable has no value for the current thread, it is first initialized to the value returned by an invocation of the initialValue() method.

Specified by:

get in interface Supplier<T>

Returns:

the current thread's value of this thread-local

set

public void set(T value)

Sets the current thread's copy of this thread-local variable to the specified value. Most subclasses will have no need to override this method, relying solely on the initialValue() method to set the values of thread-locals.

Parameters:

value - the value to be stored in the current thread's copy of this thread-local.

remove

public void remove()

Removes the current thread's value for this thread-local variable. If this thread-local variable is subsequently read by the current thread, its value will be reinitialized by invoking its initialValue() method, unless its value is set by the current thread in the interim. This may result in multiple invocations of the initialValue method in the current thread.