Simulate transient error and verify exponential backoff.

chrome/browser/sync/retry_verifier.h

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_SYNC_RETRY_VERIFIER_H_
+#define CHROME_BROWSER_SYNC_RETRY_VERIFIER_H_
+#pragma once
+
+#include "base/time.h"
+
+namespace browser_sync {
+namespace sessions {
+struct SyncSessionSnapshot;
+}
+}
+
+// The minimum and maximum wait times for a retry. The actual retry would take
+// place somewhere in this range. The algorithm that calculates the retry wait
+// time uses rand functions.
+struct DelayInfo {
+  int64 min_delay;
+  int64 max_delay;
+};
+
+// Class to verify retries take place using the exponential backoff algorithm.
+class RetryVerifier {
+ public:
+  static const int kMaxRetry = 5;
+  RetryVerifier();
+  ~RetryVerifier();
+  int RetryCount() const { return retry_count_; }
+  void Initialize(const browser_sync::sessions::SyncSessionSnapshot& snap);
+  void VerifyRetryInterval(
+      const browser_sync::sessions::SyncSessionSnapshot& snap);
+  bool Done() const { return done_; }
+  bool Success() const { return Done() && success_; }
+
+ private:
+  int retry_count_;
+  base::Time last_sync_time_;
+  DelayInfo delay_table_[kMaxRetry];
+  bool done_;
+  bool success_;
+  DISALLOW_COPY_AND_ASSIGN(RetryVerifier);
+};
+
+#endif  // CHROME_BROWSER_SYNC_RETRY_VERIFIER_H_