आइडेम्पोटेंसी और पुनःप्रयास तंत्र

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class PaymentProcessor {

    private Map<String, Boolean> processedKeys = new ConcurrentHashMap<>();

    public String processPayment(String idempotencyKey, double amount) {
        if (processedKeys.containsKey(idempotencyKey)) {
            System.out.println("Duplicate request for key: " + idempotencyKey + ". Returning previous result.");
            return "Payment already processed for key " + idempotencyKey;
        }

        // Simulate payment processing
        System.out.println("Processing payment of $" + amount + " with key: " + idempotencyKey);
        try {
            Thread.sleep(100); // Simulate work
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }

        processedKeys.put(idempotencyKey, true);
        return "Payment successful for key " + idempotencyKey;
    }

    public static void main(String[] args) {
        PaymentProcessor processor = new PaymentProcessor();

        // First attempt with a key
        System.out.println(processor.processPayment("uuid-123", 100.00));

        // Retry with the same key (should be ignored)
        System.out.println(processor.processPayment("uuid-123", 100.00));

        // New request with a different key
        System.out.println(processor.processPayment("uuid-456", 50.00));
    }
}

public class SimpleRetry {

    public static void makeApiCall() {
        int maxRetries = 3;
        int retryCount = 0;
        long delayMillis = 1000; // 1 second

        while (retryCount < maxRetries) {
            try {
                System.out.println("Attempt " + (retryCount + 1) + ": Making API call...");
                // Simulate an API call that might fail
                if (Math.random() > 0.6) { // 40% chance of success
                    System.out.println("API call successful!");
                    return; // Exit if successful
                } else {
                    throw new RuntimeException("Simulated API failure.");
                }
            } catch (RuntimeException e) {
                System.out.println("API call failed: " + e.getMessage());
                retryCount++;
                if (retryCount < maxRetries) {
                    try {
                        System.out.println("Retrying in " + delayMillis + "ms...");
                        Thread.sleep(delayMillis);
                    } catch (InterruptedException ie) {
                        Thread.currentThread().interrupt();
                        System.out.println("Retry interrupted.");
                        break;
                    }
                }
            }
        }
        System.out.println("All retry attempts failed.");
    }

    public static void main(String[] args) {
        makeApiCall();
    }
}

import java.util.Random;

public class ExponentialBackoffRetry {

    private static final Random random = new Random();

    public static void makeApiCallWithBackoff() {
        int maxRetries = 5;
        long baseDelay = 500; // milliseconds
        long maxDelay = 16000; // cap the delay at 16 seconds

        for (int retryCount = 0; retryCount < maxRetries; retryCount++) {
            try {
                System.out.println("Attempt " + (retryCount + 1) + ": Making API call...");
                // Simulate an API call that might fail
                if (Math.random() > 0.7) { // 30% chance of success
                    System.out.println("API call successful!");
                    return; // Exit if successful
                } else {
                    throw new RuntimeException("Simulated API failure.");
                }
            } catch (RuntimeException e) {
                System.out.println("API call failed: " + e.getMessage());
                if (retryCount < maxRetries - 1) {
                    long delay = baseDelay * (long) Math.pow(2, retryCount);
                    delay = Math.min(delay, maxDelay);
                    // Add jitter: random value between 0 and delay
                    long jitteredDelay = random.nextInt((int) delay);

                    try {
                        System.out.println("Retrying in " + jitteredDelay + "ms (base: " + delay + ")...");
                        Thread.sleep(jitteredDelay);
                    } catch (InterruptedException ie) {
                        Thread.currentThread().interrupt();
                        System.out.println("Retry interrupted.");
                        break;
                    }
                }
            }
        }
        System.out.println("All retry attempts failed after " + maxRetries + " retries.");
    }

    public static void main(String[] args) {
        makeApiCallWithBackoff();
    }
}