Class InheritableThreadLocal<T>
java.lang.Object
java.lang.ThreadLocal<T>
java.lang.InheritableThreadLocal<T>
- Type Parameters:
T
- the type of the inheritable thread local's value
This class extends
ThreadLocal
to provide inheritance of values
from parent thread to child thread: when a child thread is created, the
child receives initial values for all inheritable thread-local variables
for which the parent has values. Normally the child's values will be
identical to the parent's; however, the child's value can be made an
arbitrary function of the parent's by overriding the childValue
method in this class.
Inheritable thread-local variables are used in preference to ordinary thread-local variables when the per-thread-attribute being maintained in the variable (e.g., User ID, Transaction ID) must be automatically transmitted to any child threads that are created.
Note: During the creation of a new thread
, it is
possible to opt out of receiving initial values for inheritable
thread-local variables.
- Since:
- 1.2
- See Also:
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionprotected T
childValue
(T parentValue) Computes the child's initial value for this inheritable thread-local variable as a function of the parent's value at the time the child thread is created.Methods inherited from class java.lang.ThreadLocal
get, initialValue, remove, set, withInitial
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Constructor Details
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InheritableThreadLocal
public InheritableThreadLocal()Creates an inheritable thread local variable.
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Method Details
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childValue
Computes the child's initial value for this inheritable thread-local variable as a function of the parent's value at the time the child thread is created. This method is called from within the parent thread before the child is started.This method merely returns its input argument, and should be overridden if a different behavior is desired.
- Parameters:
parentValue
- the parent thread's value- Returns:
- the child thread's initial value
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