BackoffEntry is used to compute timeouts between consecutive captive portal checks.

chrome/browser/chromeos/net/network_portal_detector_impl.h

 // Copyright (c) 2013 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_CHROMEOS_NET_NETWORK_PORTAL_DETECTOR_IMPL_H_
 #define CHROME_BROWSER_CHROMEOS_NET_NETWORK_PORTAL_DETECTOR_IMPL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 64 matching lines @@
       const std::string& service_path) OVERRIDE;
   virtual bool IsEnabled() OVERRIDE;
   virtual void Enable(bool start_detection) OVERRIDE;
   virtual bool StartDetectionIfIdle() OVERRIDE;
   virtual void SetStrategy(PortalDetectorStrategy::StrategyId id) OVERRIDE;
 
   // NetworkStateHandlerObserver implementation:
   virtual void DefaultNetworkChanged(const NetworkState* network) OVERRIDE;
 
   // PortalDetectorStrategy::Delegate implementation:
-  virtual int AttemptCount() OVERRIDE;
+  virtual uint64 NoResponseResultCount() OVERRIDE;
   virtual base::TimeTicks AttemptStartTime() OVERRIDE;
   virtual base::TimeTicks GetCurrentTimeTicks() OVERRIDE;
 
  private:
   friend class NetworkPortalDetectorImplTest;
   friend class NetworkPortalDetectorImplBrowserTest;
 
   struct DetectionAttemptCompletedReport {
     DetectionAttemptCompletedReport();
 
@@ skipping 23 matching lines @@
     // Portal check is in progress.
     STATE_CHECKING_FOR_PORTAL,
   };
 
   // Starts detection process.
   void StartDetection();
 
   // Stops whole detection process.
   void StopDetection();
 
-  // Internal predicate which describes set of states from which
-  // DetectCaptivePortal() can be called.
-  bool CanPerformAttempt() const;
-
   // Initiates Captive Portal detection attempt after |delay|.
-  // You should check CanPerformAttempt() before calling this method.
   void ScheduleAttempt(const base::TimeDelta& delay);
 
   // Starts detection attempt.
   void StartAttempt();
 
   // Called when portal check is timed out. Cancels portal check and calls
   // OnPortalDetectionCompleted() with RESULT_NO_RESPONSE as a result.
   void OnAttemptTimeout();
 
   // Called by CaptivePortalDetector when detection attempt completes.
@@ skipping 18 matching lines @@
   bool is_idle() const {
     return state_ == STATE_IDLE;
   }
   bool is_portal_check_pending() const {
     return state_ == STATE_PORTAL_CHECK_PENDING;
   }
   bool is_checking_for_portal() const {
     return state_ == STATE_CHECKING_FOR_PORTAL;
   }
 
-  int attempt_count_for_testing() {
-    return attempt_count_;
+  uint64 same_detection_result_count_for_testing() const {
+    return same_detection_result_count_;
   }
 
-  void set_attempt_count_for_testing(int attempt_count) {
-    attempt_count_ = attempt_count;
+  uint64 no_response_result_count_for_testing() const {

[antrim, 2014/07/10 13:53:13]

What is the reason for using uint64 instead of int here?

[ygorshenin1, 2014/07/11 11:46:12]

Due to errors or something else int can overflow which leads to undefined
behavior in C++. So I'd prefer to use unsigned integers for monotonic counters.
uint64 is used here instead of uint32 just for safety.

On 2014/07/10 13:53:13, antrim wrote:

+    return no_response_result_count_;
+  }
+
+  void set_no_response_result_count_for_testing(uint64 count) {
+    no_response_result_count_ = count;
   }
 
   // Returns delay before next portal check. Used by unit tests.
   const base::TimeDelta& next_attempt_delay_for_testing() const {
     return next_attempt_delay_;
   }
 
   // Returns true if attempt timeout callback isn't fired or
   // cancelled.
   bool AttemptTimeoutIsCancelledForTesting() const;
 
   // Record detection stats such as detection duration and detection
   // result in UMA.
   void RecordDetectionStats(const NetworkState* network,
                             CaptivePortalStatus status);
 
+  // Resets strategy and all counters used in computations of
+  // timeouts.
+  void ResetStrategyAndCounters();
+
   // Sets current test time ticks. Used by unit tests.
   void set_time_ticks_for_testing(const base::TimeTicks& time_ticks) {
     time_ticks_for_testing_ = time_ticks;
   }
 
   // Advances current test time ticks. Used by unit tests.
   void advance_time_ticks_for_testing(const base::TimeDelta& delta) {
     time_ticks_for_testing_ += delta;
   }
 
@@ skipping 24 matching lines @@
 
   // True if the NetworkPortalDetector is enabled.
   bool enabled_;
 
   // Start time of portal detection.
   base::TimeTicks detection_start_time_;
 
   // Start time of detection attempt.
   base::TimeTicks attempt_start_time_;
 
-  // Number of already performed detection attempts.
-  int attempt_count_;
-
   // Delay before next portal detection.
   base::TimeDelta next_attempt_delay_;
 
   // Current detection strategy.
   scoped_ptr<PortalDetectorStrategy> strategy_;
 
+  // Last received result from captive portal detector.
+  CaptivePortalStatus last_detection_result_;
+
+  // Number of detection attempts with same result in a row.
+  uint64 same_detection_result_count_;
+
+  // Number of detection attempts in a row with NO RESPONSE result.
+  uint64 no_response_result_count_;
+
   // UI notification controller about captive portal state.
   NetworkPortalNotificationController notification_controller_;
 
   content::NotificationRegistrar registrar_;
 
   // Test time ticks used by unit tests.
   base::TimeTicks time_ticks_for_testing_;
 
   // Contents of a last log message about completed detection attempt.
   DetectionAttemptCompletedReport attempt_completed_report_;
 
   base::WeakPtrFactory<NetworkPortalDetectorImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkPortalDetectorImpl);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_NET_NETWORK_PORTAL_DETECTOR_IMPL_H_