1. <?php
  3. class RecordHasher {
  5. private $hash_table = [];
  6. private $rate_limit = 10; // Requests per second
  7. private $rate_limit_window = 1; // Seconds
  9. public function __construct($rate_limit = 10, $rate_limit_window = 1) {
  10. $this->rate_limit = $rate_limit;
  11. $this->rate_limit_window = $rate_limit_window;
  12. }
  14. /**
  15. * Hashes a record value and checks rate limit.
  16. *
  17. * @param string $record_value The record value to hash.
  18. * @return string|false The hashed value on success, false on rate limit exceeded.
  19. */
  20. public function hashRecord(string $record_value): string|false {
  22. $timestamp = time();
  24. // Clean up old requests
  25. $this->cleanupRateLimit($timestamp);
  27. // Check rate limit
  28. if ($this->isRateLimited()) {
  29. return false; // Rate limit exceeded
  30. }
  32. // Hash the record value
  33. $hash = hash('sha256', $record_value);
  35. // Store the hash and timestamp
  36. $this->storeHash($record_value, $hash, $timestamp);
  38. return $hash;
  39. }
  41. /**
  42. * Checks if the rate limit has been exceeded.
  43. *
  44. * @return bool True if rate limited, false otherwise.
  45. */
  46. private function isRateLimited(): bool {
  47. $now = time();
  48. $requests = array_count_values(array_filter($this->hash_table, function ($item) use ($now) => $now - $item['timestamp'] < $this->rate_limit_window));
  50. if (isset($requests[$now])) {
  51. if ($requests[$now] >= $this->rate_limit) {
  52. return true;
  53. }
  54. }
  55. return false;
  56. }
  58. /**
  59. * Cleans up old requests from the hash table.
  60. *
  61. * @param int $timestamp The current timestamp.
  62. */
  63. private function cleanupRateLimit(int $timestamp): void {
  64. $this->hash_table = array_filter($this->hash_table, function ($item) use ($timestamp) {
  65. return $timestamp - $item['timestamp'] < $this->rate_limit_window;
  66. });
  67. }
  70. /**
  71. * Stores the hash and timestamp.
  72. *
  73. * @param string $record_value The record value.
  74. * @param string $hash The hashed value.
  75. * @param int $timestamp The timestamp.
  76. */
  77. private function storeHash(string $record_value, string $hash, int $timestamp): void {
  78. $this->hash_table[] = ['record_value' => $record_value, 'hash' => $hash, 'timestamp' => $timestamp];
  79. }
  80. }
  82. ?>

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