PromiseTask Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/concurrent/PromiseTask.java lines 21–188

class PromiseTask<V> extends DefaultPromise<V> implements RunnableFuture<V> {

    private static final class RunnableAdapter<T> implements Callable<T> {
        final Runnable task;
        final T result;

        RunnableAdapter(Runnable task, T result) {
            this.task = task;
            this.result = result;
        }

        @Override
        public T call() {
            task.run();
            return result;
        }

        @Override
        public String toString() {
            return "Callable(task: " + task + ", result: " + result + ')';
        }
    }

    private static final Runnable COMPLETED = new SentinelRunnable("COMPLETED");
    private static final Runnable CANCELLED = new SentinelRunnable("CANCELLED");
    private static final Runnable FAILED = new SentinelRunnable("FAILED");

    private static class SentinelRunnable implements Runnable {
        private final String name;

        SentinelRunnable(String name) {
            this.name = name;
        }

        @Override
        public void run() { } // no-op

        @Override
        public String toString() {
            return name;
        }
    }

    // Strictly of type Callable<V> or Runnable
    private Object task;

    PromiseTask(EventExecutor executor, Runnable runnable, V result) {
        super(executor);
        task = result == null ? runnable : new RunnableAdapter<V>(runnable, result);
    }

    PromiseTask(EventExecutor executor, Runnable runnable) {
        super(executor);
        task = runnable;
    }

    PromiseTask(EventExecutor executor, Callable<V> callable) {
        super(executor);
        task = callable;
    }

    @Override
    public final int hashCode() {
        return System.identityHashCode(this);
    }

    @Override
    public final boolean equals(Object obj) {
        return this == obj;
    }

    @SuppressWarnings("unchecked")
    V runTask() throws Throwable {
        final Object task = this.task;
        if (task instanceof Callable) {
            return ((Callable<V>) task).call();
        }
        ((Runnable) task).run();
        return null;
    }