public static final class Asynchronous.Result
extends java.lang.Object
CompletableFuture
instance that the Jakarta EE Product Provider supplies to the caller
of the asynchronous method.
Before invoking the asynchronous method implementation on a thread,
the Jakarta EE Product Provider invokes the setFuture(java.util.concurrent.CompletableFuture<T>) method
which makes available to the asynchronous method implementation
the same CompletableFuture that the Jakarta EE Product Provider
returns to the caller.
The asynchronous method implementation invokes the getFuture() method
to obtain the same CompletableFuture that the
Jakarta EE Product Provider returns to the caller.
The asynchronous method implementation can choose to complete
this future (normally or exceptionally) or otherwise arrange for its
completion, for example upon completion of a pipeline of completion stages.
Having this same CompletableFuture also enables the asynchronous
method implementation to determine if the caller has forcibly completed
(such as by cancellation or any other means) the CompletableFuture,
in which case the asynchronous method implementation could decide to end
immediately rather than continue processing.
For example,
@Asynchronous
public CompletableFuture <Double> hoursWorked(LocalDateTime from, LocalDateTime to) {
CompletableFuture <Double> future = Asynchronous.Result.getFuture();
if (future.isDone())
return future;
try (Connection con = ((DataSource) InitialContext.doLookup(
"java:comp/env/jdbc/timesheetDB")).getConnection()) {
...
for (ResultSet result = stmt.executeQuery(); result.next() && !future.isDone(); )
...
future.complete(total);
} catch (NamingException | SQLException x) {
future.completeExceptionally(x);
}
return future;
}
After the asynchronous method completes, the Jakarta EE Product Provider
invokes the setFuture(java.util.concurrent.CompletableFuture<T>) method with a null value
to clear it from the thread.| Modifier and Type | Method and Description |
|---|---|
static <T> java.util.concurrent.CompletableFuture<T> |
complete(T result)
Completes the
CompletableFuture
instance that the Jakarta EE Product Provider supplies to the caller of the
asynchronous method. |
static <T> java.util.concurrent.CompletableFuture<T> |
getFuture()
Obtains the same
CompletableFuture
instance that the Jakarta EE Product Provider supplies to the caller of the
asynchronous method. |
static <T> void |
setFuture(java.util.concurrent.CompletableFuture<T> future)
Before invoking the asynchronous method implementation on a thread,
the Jakarta EE Product Provider invokes this method to make available
to the asynchronous method implementation the same
CompletableFuture
that the Jakarta EE Product Provider returns to the caller. |
public static <T> java.util.concurrent.CompletableFuture<T> complete(T result)
CompletableFuture
instance that the Jakarta EE Product Provider supplies to the caller of the
asynchronous method.
This method must only be invoked by the asynchronous method implementation.
T - type of result returned by the asynchronous method's CompletableFuture.result - result with which to complete the asynchronous method's CompletableFuture.CompletableFuture that the container returns to the caller.java.lang.IllegalStateException - if the CompletableFuture for an asynchronous
method is not present on the thread.public static <T> java.util.concurrent.CompletableFuture<T> getFuture()
CompletableFuture
instance that the Jakarta EE Product Provider supplies to the caller of the
asynchronous method.
This method must only be invoked by the asynchronous method implementation.
T - type of result returned by the asynchronous method's CompletableFuture.CompletableFuture that the container returns to the caller.java.lang.IllegalStateException - if the CompletableFuture for an asynchronous
method is not present on the thread.public static <T> void setFuture(java.util.concurrent.CompletableFuture<T> future)
CompletableFuture
that the Jakarta EE Product Provider returns to the caller.
After the asynchronous method completes, the Jakarta EE Product Provider
invokes this method with a null value
to clear it from the thread.
This method must only be invoked by the Jakarta EE Product Provider.
T - type of result returned by the asynchronous method's CompletableFuture.future - CompletableFuture that the container returns to the caller,
or null to clear it.