Examples with DefaultPromise ratpack.exec.internal.DefaultPromise used on opensource projects

Example 1 with DefaultPromise

use of ratpack.exec.internal.DefaultPromise in project ratpack by ratpack.

the class Blocking method get.

/**
   * Performs a blocking operation on a separate thread, returning a promise for its value.
   * <p>
   * This method should be used to perform blocking IO, or to perform any operation that synchronously waits for something to happen.
   * The given factory function will be executed on a thread from a special pool for such operations (i.e. not a thread from the main compute event loop).
   * <p>
   * The operation should do as little computation as possible.
   * It should just perform the blocking operation and immediately return the result.
   * Performing computation during the operation will degrade performance.
   *
   * @param factory the operation that blocks
   * @param <T> the type of value created by the operation
   * @return a promise for the return value of the given blocking operation
   */
public static <T> Promise<T> get(Factory<T> factory) {
    return new DefaultPromise<>(downstream -> {
        DefaultExecution execution = DefaultExecution.require();
        EventLoop eventLoop = execution.getEventLoop();
        execution.delimit(downstream::error, continuation -> eventLoop.execute(() -> CompletableFuture.supplyAsync(new Supplier<Result<T>>() {

            Result<T> result;

            @Override
            public Result<T> get() {
                try {
                    DefaultExecution.THREAD_BINDING.set(execution);
                    intercept(execution, execution.getAllInterceptors().iterator(), () -> {
                        try {
                            result = Result.success(factory.create());
                        } catch (Throwable e) {
                            result = Result.error(e);
                        }
                    });
                    return result;
                } catch (Throwable e) {
                    DefaultExecution.interceptorError(e);
                    return result;
                } finally {
                    DefaultExecution.THREAD_BINDING.remove();
                }
            }
        }, execution.getController().getBlockingExecutor()).thenAcceptAsync(v -> continuation.resume(() -> downstream.accept(v)), eventLoop)));
    });
}