CallbackToFutureAdapter

class CallbackToFutureAdapter

A utility useful for adapting interfaces that take callbacks into interfaces that return .

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 or the passed-in tag object, as this will defeat the best-effort early failure detection based on garbage collection.

Summary

Nested types

Used to complete the future returned by getFuture

This interface should be implemented by the object passed into getFuture.

Public functions
java-static ListenableFuture<T!>

Returns a Future that will be completed by the Completer provided in attachCompleter.

Public functions

getFuture

Added in 1.0.0
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.