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package org.eclipse.jetty.util.thread;
import java.util.concurrent.Callable;
A task (typically either a Runnable
or Callable
that declares how it will behave when invoked:
- blocking, the invocation will certainly block (e.g. performs blocking I/O)
- non-blocking, the invocation will certainly not block
- either, the invocation may block
Static methods and are provided that allow the current thread to be tagged with a ThreadLocal
to indicate if it has a blocking invocation type.
/**
* <p>A task (typically either a {@link Runnable} or {@link Callable}
* that declares how it will behave when invoked:</p>
* <ul>
* <li>blocking, the invocation will certainly block (e.g. performs blocking I/O)</li>
* <li>non-blocking, the invocation will certainly <strong>not</strong> block</li>
* <li>either, the invocation <em>may</em> block</li>
* </ul>
*
* <p>
* Static methods and are provided that allow the current thread to be tagged
* with a {@link ThreadLocal} to indicate if it has a blocking invocation type.
* </p>
*/
public interface Invocable
{
enum InvocationType
{
BLOCKING, NON_BLOCKING, EITHER
}
static ThreadLocal<Boolean> __nonBlocking = new ThreadLocal<>();
Test if the current thread has been tagged as non blocking
Returns: True if the task the current thread is running has
indicated that it will not block.
/**
* Test if the current thread has been tagged as non blocking
*
* @return True if the task the current thread is running has
* indicated that it will not block.
*/
public static boolean isNonBlockingInvocation()
{
return Boolean.TRUE.equals(__nonBlocking.get());
}
Invoke a task with the calling thread, tagged to indicate
that it will not block.
Params: - task – The task to invoke.
/**
* Invoke a task with the calling thread, tagged to indicate
* that it will not block.
*
* @param task The task to invoke.
*/
public static void invokeNonBlocking(Runnable task)
{
Boolean wasNonBlocking = __nonBlocking.get();
try
{
__nonBlocking.set(Boolean.TRUE);
task.run();
}
finally
{
__nonBlocking.set(wasNonBlocking);
}
}
Get the invocation type of an Object.
Params: - o – The object to check the invocation type of.
Returns: If the object is an Invocable, it is coerced and the getInvocationType()
used, otherwise InvocationType.BLOCKING
is returned.
/**
* Get the invocation type of an Object.
*
* @param o The object to check the invocation type of.
* @return If the object is an Invocable, it is coerced and the {@link #getInvocationType()}
* used, otherwise {@link InvocationType#BLOCKING} is returned.
*/
public static InvocationType getInvocationType(Object o)
{
if (o instanceof Invocable)
return ((Invocable)o).getInvocationType();
return InvocationType.BLOCKING;
}
Returns: The InvocationType of this object
/**
* @return The InvocationType of this object
*/
default InvocationType getInvocationType()
{
return InvocationType.BLOCKING;
}
}