import com.google.ipc.invalidation.util.ExponentialBackoffDelayGenerator; //导入依赖的package包/类
/**
 * A utility function to run an async runnable with exponential backoff after failures.
 * @param runnable the asynchronous runnable.
 * @param scheduler used to schedule retries.
 * @param backOffGenerator a backoff generator that returns how to long to wait between retries.
 *     The client must pass a new instance or reset the backoff generator before calling this
 *     method.
 */

static void retryUntilSuccessWithBackoff(final SystemResources.Scheduler scheduler,
    final ExponentialBackoffDelayGenerator backOffGenerator, final AsyncRunnable runnable) {
  logger.fine("Running %s", runnable);
  runnable.run(new CompletionCallback() {
      @Override
      public void success() {
        logger.fine("%s succeeded", runnable);
      }

      @Override
      public void failure() {
        int nextDelay = backOffGenerator.getNextDelay();
        logger.fine("%s failed, retrying after %s ms", nextDelay);
        scheduler.schedule(nextDelay, new Runnable() {
          @Override
          public void run() {
            retryUntilSuccessWithBackoff(scheduler, backOffGenerator, runnable);
          }
        });
      }
  });
}
 

import com.google.ipc.invalidation.util.ExponentialBackoffDelayGenerator; //导入依赖的package包/类
@Override
public void setSystemResources(SystemResources resources) {
  this.resources = resources;

  // Prefetch the auth sub token.  Since this might require an HTTP round trip, we do this
  // as soon as the resources are available.
  // TODO: Find a better place to fetch the auth token; this method
  // doesn't sound like one that should be doing work.
  retryUntilSuccessWithBackoff(resources.getInternalScheduler(),
      new ExponentialBackoffDelayGenerator(
          new Random(), INITIAL_AUTH_TOKEN_RETRY_DELAY_MS, MAX_AUTH_TOKEN_RETRY_FACTOR),
      new AsyncRunnable() {
        @Override
        public void run(CompletionCallback callback) {
          requestAuthToken(callback);
        }
      });
}
 

import com.google.ipc.invalidation.util.ExponentialBackoffDelayGenerator; //导入依赖的package包/类
/** Returns the delay generator, if any. */
ExponentialBackoffDelayGenerator getDelayGenerator() {
  return delayGenerator;
}