org.apache.calcite.util

Class TryThreadLocal<T>

java.lang.Object

java.lang.ThreadLocal<T>

org.apache.calcite.util.TryThreadLocal<T>

Type Parameters:

T - Value type

public class TryThreadLocal<T>
extends ThreadLocal<T>

Thread-local variable that returns a handle that can be closed.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	TryThreadLocal.Memo Remembers to set the value back.

Method Summary

Modifier and Type	Method and Description
protected T	initialValue()
void	letIn(T t, Runnable runnable) Performs an action with this ThreadLocal set to a particular value in this thread, and restores the previous value afterwards.
<R> R	letIn(T t, Supplier<R> supplier) Calls a Supplier with this ThreadLocal set to a particular value, in this thread, and restores the previous value afterwards.
static <T> TryThreadLocal<T>	of(T initialValue) Creates a TryThreadLocal.
TryThreadLocal.Memo	push(T value) Assigns the value as value for the current thread.
protected void	restoreTo(T previous) Sets the value back to a previous value.

Methods inherited from class java.lang.ThreadLocal

get, remove, set, withInitial

Methods inherited from class java.lang.Object

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

Method Detail

of

public static <T> TryThreadLocal<T> of(T initialValue)

Creates a TryThreadLocal.

Parameters:

initialValue - Initial value

initialValue

protected final T initialValue()

Overrides:

initialValue in class ThreadLocal<T>

push

public TryThreadLocal.Memo push(T value)

Assigns the value as value for the current thread. Returns a TryThreadLocal.Memo which, when closed, will assign the value back to the previous value.

restoreTo

protected void restoreTo(T previous)

Sets the value back to a previous value.

If the previous value was initialValue, calls ThreadLocal.remove(). There's no way to tell whether ThreadLocal.set(T) has been called previously, but the effect is the same.

letIn

public void letIn(T t,
                  Runnable runnable)

Performs an action with this ThreadLocal set to a particular value in this thread, and restores the previous value afterwards.

This method is named after the Standard ML let construct, for example let val x = 1 in x + 2 end.

letIn

public <R> R letIn(T t,
                   Supplier<R> supplier)

Calls a Supplier with this ThreadLocal set to a particular value, in this thread, and restores the previous value afterwards.

This method is named after the Standard ML let construct, for example let val x = 1 in x + 2 end.