CallbackToFutureAdapter
class CallbackToFutureAdapter
A utility useful for adapting interfaces that take callbacks into interfaces that return ListenableFuture.
It also provides additional safety checks, failing the future if it will never complete.
For example, you work with the following async api:
class AsyncApi { interface OnResult { void onSuccess(Foo foo); void onError(Failure failure); } void load(OnResult onResult) {} }
Code that wraps it as ListenableFuture would look like:
ListenableFuture<Foo> asyncOperation() { return CallbackToFutureAdapter.getFuture(completer -> { asyncApi.load(new OnResult() { @Override public void onSuccess(Foo foo) { completer.set(foo); } @Override public void onError(Failure failure) { completer.setException(failure.exception); } }); // This value is used only for debug purposes: it will be used in toString() // of returned future or error cases. return "AsyncApi.load operation"; }); }
Try to avoid creating references from listeners on the returned Future to the Completer or the passed-in tag object, as this will defeat the best-effort early failure detection based on garbage collection.
Summary
Nested types |
|---|
class CallbackToFutureAdapter.Completer<T>Used to complete the future returned by |
interface CallbackToFutureAdapter.Resolver<T>This interface should be implemented by the object passed into |
Public functions |
|
|---|---|
java-static ListenableFuture<T!> |
<T> getFuture(callback: CallbackToFutureAdapter.Resolver<T!>)Returns a Future that will be completed by the |
Public functions
getFuture
java-static fun <T> getFuture(callback: CallbackToFutureAdapter.Resolver<T!>): ListenableFuture<T!>
Returns a Future that will be completed by the Completer provided in attachCompleter.
The provided callback is invoked immediately inline. Any exceptions thrown by it will fail the returned Future.