Non Blocking Channel Operations in Miranda

Our example demonstrates non-blocking channel operations using Java’s BlockingQueue interface and the offer and poll methods with timeouts. While Java doesn’t have built-in channels like Go, we can achieve similar functionality using concurrent collections.

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;

public class NonBlockingOperations {
    public static void main(String[] args) {
        BlockingQueue<String> messages = new LinkedBlockingQueue<>();
        BlockingQueue<Boolean> signals = new LinkedBlockingQueue<>();

        // Here's a non-blocking receive. If a value is
        // available in `messages` then `poll` will return
        // that value. If not, it will immediately return null.
        String msg = messages.poll();
        if (msg != null) {
            System.out.println("received message " + msg);
        } else {
            System.out.println("no message received");
        }

        // A non-blocking send works similarly. Here `msg`
        // cannot be sent to the `messages` queue if it's full.
        // The `offer` method will return false if the element
        // cannot be added.
        msg = "hi";
        if (messages.offer(msg)) {
            System.out.println("sent message " + msg);
        } else {
            System.out.println("no message sent");
        }

        // We can use multiple conditions to implement a multi-way
        // non-blocking select. Here we attempt non-blocking receives
        // on both `messages` and `signals`.
        String receivedMsg = messages.poll();
        Boolean receivedSignal = signals.poll();

        if (receivedMsg != null) {
            System.out.println("received message " + receivedMsg);
        } else if (receivedSignal != null) {
            System.out.println("received signal " + receivedSignal);
        } else {
            System.out.println("no activity");
        }
    }
}

In this Java implementation:

We use BlockingQueue<String> and BlockingQueue<Boolean> instead of channels. LinkedBlockingQueue is used as the concrete implementation.
The poll() method is used for non-blocking receives. It immediately returns null if the queue is empty.
The offer(E e) method is used for non-blocking sends. It returns false if the element cannot be added to the queue (e.g., if the queue is full).
To simulate a multi-way select, we use multiple if-else conditions checking the results of poll() on different queues.

This code demonstrates how to perform non-blocking operations in Java, which is conceptually similar to non-blocking channel operations in other languages. The BlockingQueue interface provides additional methods like offer(E e, long timeout, TimeUnit unit) and poll(long timeout, TimeUnit unit) for operations with timeouts, which can be useful in more complex scenarios.

To run this program:

$ javac NonBlockingOperations.java
$ java NonBlockingOperations
no message received
no message sent
no activity

This output shows that no messages were available in the queues, demonstrating the non-blocking nature of the operations.

Timeouts in Miranda

Closing Channels in Miranda

Learn X By Example

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Non Blocking Channel Operations in Miranda