| 67 | |
| 68 | |
| 69 | class DeferredRefreshableToken: |
| 70 | # The time at which we'll attempt to refresh, but not block if someone else |
| 71 | # is refreshing. |
| 72 | _advisory_refresh_timeout = 15 * 60 |
| 73 | # The time at which all threads will block waiting for a refreshed token |
| 74 | _mandatory_refresh_timeout = 10 * 60 |
| 75 | # Refresh at most once every minute to avoid blocking every request |
| 76 | _attempt_timeout = 60 |
| 77 | |
| 78 | def __init__(self, method, refresh_using, time_fetcher=_utc_now): |
| 79 | self._time_fetcher = time_fetcher |
| 80 | self._refresh_using = refresh_using |
| 81 | self.method = method |
| 82 | |
| 83 | # The frozen token is protected by this lock |
| 84 | self._refresh_lock = threading.Lock() |
| 85 | self._frozen_token = None |
| 86 | self._next_refresh = None |
| 87 | |
| 88 | def get_frozen_token(self): |
| 89 | self._refresh() |
| 90 | return self._frozen_token |
| 91 | |
| 92 | def _refresh(self): |
| 93 | # If we don't need to refresh just return |
| 94 | refresh_type = self._should_refresh() |
| 95 | if not refresh_type: |
| 96 | return None |
| 97 | |
| 98 | # Block for refresh if we're in the mandatory refresh window |
| 99 | block_for_refresh = refresh_type == "mandatory" |
| 100 | if self._refresh_lock.acquire(block_for_refresh): |
| 101 | try: |
| 102 | self._protected_refresh() |
| 103 | finally: |
| 104 | self._refresh_lock.release() |
| 105 | |
| 106 | def _protected_refresh(self): |
| 107 | # This should only be called after acquiring the refresh lock |
| 108 | # Another thread may have already refreshed, double check refresh |
| 109 | refresh_type = self._should_refresh() |
| 110 | if not refresh_type: |
| 111 | return None |
| 112 | |
| 113 | try: |
| 114 | now = self._time_fetcher() |
| 115 | self._next_refresh = now + timedelta(seconds=self._attempt_timeout) |
| 116 | self._frozen_token = self._refresh_using() |
| 117 | except Exception: |
| 118 | logger.warning( |
| 119 | "Refreshing token failed during the %s refresh period.", |
| 120 | refresh_type, |
| 121 | exc_info=True, |
| 122 | ) |
| 123 | if refresh_type == "mandatory": |
| 124 | # This refresh was mandatory, error must be propagated back |
| 125 | raise |
| 126 | |