/**
* Calls {@link OAuth2Credentials#refreshAccessToken()}. In case of an IOException, retry the call
* as per the {@link BackOff} policy defined by {@link RetryOptions#createBackoff()}.
*
* <p>This method retries until one of the following conditions occurs:
*
* <ol>
* <li>An OAuth request was completed. If the value is null, return an exception.
* <li>A non-IOException Exception is thrown - return an error status
* <li>All retries have been exhausted, i.e. when the Backoff.nextBackOffMillis() returns
* BackOff.STOP
* <li>An interrupt occurs.
* </ol>
*
* @return HeaderCacheElement containing either a valid {@link AccessToken} or an exception.
*/
protected HeaderCacheElement refreshCredentialsWithRetry() {
BackOff backoff = null;
while (true) {
try {
logger.info("Refreshing the OAuth token");
AccessToken newToken = credentials.refreshAccessToken();
if (newToken == null) {
// The current implementations of refreshAccessToken() throws an IOException or return
// a valid token. This handling is future proofing just in case credentials returns null
// for
// some reason. This case was caught by a poorly coded unit test.
logger.info("Refreshed the OAuth token");
return new HeaderCacheElement(
new IOException("Could not load the token for credentials: " + credentials));
} else {
// Success!
return new HeaderCacheElement(newToken);
}
} catch (IOException exception) {
logger.warn("Got an unexpected IOException when refreshing google credentials.", exception);
// An IOException occurred. Retry with backoff.
if (backoff == null) {
// initialize backoff.
backoff = retryOptions.createBackoff();
}
// Given the backoff, either sleep for a short duration, or terminate if the backoff has
// reached its configured timeout limit.
try {
RetryState retryState = getRetryState(backoff);
if (retryState != RetryState.PerformRetry) {
return new HeaderCacheElement(exception);
} // else Retry.
} catch (IOException e) {
logger.warn("Got an exception while trying to run backoff.nextBackOffMillis()", e);
return new HeaderCacheElement(exception);
}
} catch (Exception e) {
logger.warn("Got an unexpected exception while trying to refresh google credentials.", e);
return new HeaderCacheElement(new IOException("Could not read headers", e));
}
}
}
