java - Cancellation of CompletableFuture controlled by ExecutorService -

i have executorservice forwards computed data completablefuture:

class dataretriever {     private final executorservice service = ...;      public completablefuture<data> retrieve() {         final completablefuture<data> future = new completablefuture<>();          service.execute(() -> {             final data data = ... fetch data ...             future.complete(data);         });         return future;     } } 

i want client/user able cancel task:

final dataretriever retriever = new dataretriever(); final completablefuture<data> future = retriever().retrieve();  future.cancel(true); 

this not work, cancels outer completablefuture, not inner future scheduled in executor service.

is somehow possible propagate cancel() on outer future inner future?

completablefuture#cancel serves purpose of marking completablefuture cancelled. nothing notify executing task stop, because has no relationship such task.

the javadoc hints @ this

mayinterruptifrunning - value has no effect in implementation because interrupts not used control processing.

the inner future in example future, not completablefuture, , have relation executing runnable (or callable). internally, since know thread task executing on, can send interrupt attempt stop it.

one option return tuple of sorts (eg. pojo) provides reference both completablefuture , future returned executorservice#submit. can use future cancel if need to. you'd have remember cancel or complete completablefuture other parts of code don't remain blocked/starved forever.