1. import java.util.concurrent.TimeUnit;
  2. import java.util.concurrent.TimeoutException;
  4. public class EntryMonitor {
  6. /**
  7. * Monitors an entry and retries if the condition is not met.
  8. *
  9. * @param entry The entry to monitor.
  10. * @param condition A function that returns true if the entry is valid.
  11. * @param maxRetries The maximum number of retry attempts.
  12. * @param initialDelay The initial delay between retries (in seconds).
  13. * @param timeout The maximum time to wait for the entry to become valid (in seconds).
  14. * @return The entry if the condition is met within the retry limit, otherwise null.
  15. * @throws TimeoutException If the timeout is reached.
  16. */
  17. public static <T> T monitorEntry(T entry, ConditionFunction<T> condition, int maxRetries, long initialDelay, long timeout) throws TimeoutException {
  18. for (int retry = 0; retry <= maxRetries; retry++) {
  19. if (condition.check(entry)) {
  20. return entry; // Condition met, return entry
  21. }
  23. if (retry < maxRetries) {
  24. try {
  25. TimeUnit.SECONDS.sleep(initialDelay);
  26. } catch (InterruptedException e) {
  27. Thread.currentThread().interrupt(); // Restore interrupted status
  28. return null;
  29. }
  30. initialDelay *= 2; // Exponential backoff
  31. } else {
  32. throw new TimeoutException("Timed out after " + maxRetries + " retries.");
  33. }
  34. }
  35. return null; // Condition not met after all retries
  36. }
  38. /**
  39. * Functional interface for defining the condition to check for an entry.
  40. *
  41. * @param <T> The type of the entry.
  42. */
  43. public interface ConditionFunction<T> {
  44. boolean check(T entry);
  45. }
  47. public static void main(String[] args) throws TimeoutException {
  48. // Example Usage
  49. Integer myEntry = 0;
  50. ConditionFunction<Integer> isPositive = entry -> entry > 0;
  52. Integer validatedEntry = monitorEntry(myEntry, isPositive, 3, 1, 5);
  54. if (validatedEntry != null) {
  55. System.out.println("Entry is valid: " + validatedEntry);
  56. } else {
  57. System.out.println("Entry is invalid after multiple retries.");
  58. }
  59. }
  60. }

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