Method select

src/main/java/groovy/concurrent/ChannelSelect.java:85–107

Waits for the first value available from any of the channels. Returns an Awaitable that completes with a Result containing the channel index and the received value. Values consumed by non-winning channels are re-sent back to those channels to prevent message loss. This may re

()

     * @return an awaitable result indicating which channel produced the value
     */
    @SuppressWarnings("unchecked")
    public Awaitable<Result> select() {
        CompletableFuture<Result> winner = new CompletableFuture<>();
        AtomicBoolean won = new AtomicBoolean();
        for (int i = 0; i < channels.size(); i++) {
            final int index = i;
            AsyncChannel<?> ch = channels.get(i);
            ch.receive().toCompletableFuture().whenComplete((value, error) -> {
                if (error != null) return;
                if (won.compareAndSet(false, true)) {
                    winner.complete(new Result(index, value));
                } else {
                    // Re-send the consumed value back to avoid message loss
                    try {
                        ((AsyncChannel<Object>) ch).send(value);
                    } catch (ChannelClosedException ignored) {
                        // Channel was closed; value cannot be preserved
                    }
                }
            });
        }
        return GroovyPromise.of(winner);
    }

    /**
     * The result of a {@link #select()} operation, indicating which