Stateful Goroutines in CLIPS

In this example, we’ll demonstrate how to manage state using threads and synchronization in Java. This approach aligns with Java’s concurrency model and ensures that each piece of data is accessed safely in a multi-threaded environment.

import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.atomic.AtomicLong;

class ReadOp {
    int key;
    int value;

    ReadOp(int key) {
        this.key = key;
    }
}

class WriteOp {
    int key;
    int value;

    WriteOp(int key, int value) {
        this.key = key;
        this.value = value;
    }
}

public class StatefulThreads {
    public static void main(String[] args) throws InterruptedException {
        AtomicLong readOps = new AtomicLong();
        AtomicLong writeOps = new AtomicLong();

        // Create a thread for managing state
        Thread stateManager = new Thread(() -> {
            Map<Integer, Integer> state = new HashMap<>();
            while (true) {
                synchronized (StatefulThreads.class) {
                    try {
                        StatefulThreads.class.wait();
                    } catch (InterruptedException e) {
                        break;
                    }
                    
                    if (Thread.currentThread().isInterrupted()) {
                        break;
                    }
                }
            }
        });
        stateManager.start();

        // Start 100 read threads
        for (int r = 0; r < 100; r++) {
            new Thread(() -> {
                Random rand = new Random();
                while (!Thread.currentThread().isInterrupted()) {
                    ReadOp read = new ReadOp(rand.nextInt(5));
                    synchronized (StatefulThreads.class) {
                        StatefulThreads.class.notify();
                    }
                    readOps.incrementAndGet();
                    try {
                        Thread.sleep(1);
                    } catch (InterruptedException e) {
                        break;
                    }
                }
            }).start();
        }

        // Start 10 write threads
        for (int w = 0; w < 10; w++) {
            new Thread(() -> {
                Random rand = new Random();
                while (!Thread.currentThread().isInterrupted()) {
                    WriteOp write = new WriteOp(rand.nextInt(5), rand.nextInt(100));
                    synchronized (StatefulThreads.class) {
                        StatefulThreads.class.notify();
                    }
                    writeOps.incrementAndGet();
                    try {
                        Thread.sleep(1);
                    } catch (InterruptedException e) {
                        break;
                    }
                }
            }).start();
        }

        // Let the threads work for a second
        Thread.sleep(1000);

        // Capture and report the op counts
        System.out.println("readOps: " + readOps.get());
        System.out.println("writeOps: " + writeOps.get());

        // Interrupt all threads
        stateManager.interrupt();
    }
}

In this Java implementation, we use threads to simulate concurrent operations. The stateManager thread owns the state (a HashMap) and processes read and write operations. We use synchronized blocks and wait()/notify() methods for inter-thread communication.

The ReadOp and WriteOp classes encapsulate read and write operations. We use AtomicLong for thread-safe counting of operations.

We start 100 read threads and 10 write threads, each performing operations in a loop. After letting the threads run for a second, we print the total number of read and write operations performed.

Running this program might produce output similar to:

readOps: 71708
writeOps: 7177

This thread-based approach in Java is more complex than using simple locks, but it can be useful in certain scenarios, especially when dealing with multiple resources or when you need fine-grained control over concurrency. Choose the approach that makes your program easiest to understand and reason about in terms of correctness.

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Stateful Goroutines in CLIPS