| // Copyright (c) 2012 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 NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_H_ |
| #define NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_H_ |
| |
| #include <stdint.h> |
| |
| #include <string> |
| |
| #include "base/containers/queue.h" |
| #include "base/macros.h" |
| #include "base/time/time.h" |
| #include "net/base/backoff_entry.h" |
| #include "net/base/net_export.h" |
| #include "net/log/net_log_with_source.h" |
| #include "net/url_request/url_request_throttler_entry_interface.h" |
| |
| namespace net { |
| |
| class URLRequestThrottlerManager; |
| |
| // URLRequestThrottlerEntry represents an entry of URLRequestThrottlerManager. |
| // It analyzes requests of a specific URL over some period of time, in order to |
| // deduce the back-off time for every request. |
| // The back-off algorithm consists of two parts. Firstly, exponential back-off |
| // is used when receiving 5XX server errors or malformed response bodies. |
| // The exponential back-off rule is enforced by URLRequestHttpJob. Any |
| // request sent during the back-off period will be cancelled. |
| // Secondly, a sliding window is used to count recent requests to a given |
| // destination and provide guidance (to the application level only) on whether |
| // too many requests have been sent and when a good time to send the next one |
| // would be. This is never used to deny requests at the network level. |
| class NET_EXPORT URLRequestThrottlerEntry |
| : public URLRequestThrottlerEntryInterface { |
| public: |
| // Sliding window period. |
| static const int kDefaultSlidingWindowPeriodMs; |
| |
| // Maximum number of requests allowed in sliding window period. |
| static const int kDefaultMaxSendThreshold; |
| |
| // Number of initial errors to ignore before starting exponential back-off. |
| static const int kDefaultNumErrorsToIgnore; |
| |
| // Initial delay for exponential back-off. |
| static const int kDefaultInitialDelayMs; |
| |
| // Factor by which the waiting time will be multiplied. |
| static const double kDefaultMultiplyFactor; |
| |
| // Fuzzing percentage. ex: 10% will spread requests randomly |
| // between 90%-100% of the calculated time. |
| static const double kDefaultJitterFactor; |
| |
| // Maximum amount of time we are willing to delay our request. |
| static const int kDefaultMaximumBackoffMs; |
| |
| // Time after which the entry is considered outdated. |
| static const int kDefaultEntryLifetimeMs; |
| |
| // The manager object's lifetime must enclose the lifetime of this object. |
| URLRequestThrottlerEntry(URLRequestThrottlerManager* manager, |
| const std::string& url_id); |
| |
| // The life span of instances created with this constructor is set to |
| // infinite, and the number of initial errors to ignore is set to 0. |
| // It is only used by unit tests. |
| URLRequestThrottlerEntry(URLRequestThrottlerManager* manager, |
| const std::string& url_id, |
| int sliding_window_period_ms, |
| int max_send_threshold, |
| int initial_backoff_ms, |
| double multiply_factor, |
| double jitter_factor, |
| int maximum_backoff_ms); |
| |
| // Used by the manager, returns true if the entry needs to be garbage |
| // collected. |
| bool IsEntryOutdated() const; |
| |
| // Causes this entry to never reject requests due to back-off. |
| void DisableBackoffThrottling(); |
| |
| // Causes this entry to NULL its manager pointer. |
| void DetachManager(); |
| |
| // Implementation of URLRequestThrottlerEntryInterface. |
| bool ShouldRejectRequest(const URLRequest& request) const override; |
| int64_t ReserveSendingTimeForNextRequest( |
| const base::TimeTicks& earliest_time) override; |
| base::TimeTicks GetExponentialBackoffReleaseTime() const override; |
| void UpdateWithResponse(int status_code) override; |
| void ReceivedContentWasMalformed(int response_code) override; |
| |
| protected: |
| ~URLRequestThrottlerEntry() override; |
| |
| void Initialize(); |
| |
| // Returns true if the given response code is considered a success for |
| // throttling purposes. |
| bool IsConsideredSuccess(int response_code); |
| |
| // Equivalent to TimeTicks::Now(), virtual to be mockable for testing purpose. |
| virtual base::TimeTicks ImplGetTimeNow() const; |
| |
| // Retrieves the back-off entry object we're using. Used to enable a |
| // unit testing seam for dependency injection in tests. |
| virtual const BackoffEntry* GetBackoffEntry() const; |
| virtual BackoffEntry* GetBackoffEntry(); |
| |
| // Used by tests. |
| base::TimeTicks sliding_window_release_time() const { |
| return sliding_window_release_time_; |
| } |
| |
| // Used by tests. |
| void set_sliding_window_release_time(const base::TimeTicks& release_time) { |
| sliding_window_release_time_ = release_time; |
| } |
| |
| // Valid and immutable after construction time. |
| BackoffEntry::Policy backoff_policy_; |
| |
| private: |
| // Timestamp calculated by the sliding window algorithm for when we advise |
| // clients the next request should be made, at the earliest. Advisory only, |
| // not used to deny requests. |
| base::TimeTicks sliding_window_release_time_; |
| |
| // A list of the recent send events. We use them to decide whether there are |
| // too many requests sent in sliding window. |
| base::queue<base::TimeTicks> send_log_; |
| |
| const base::TimeDelta sliding_window_period_; |
| const int max_send_threshold_; |
| |
| // True if DisableBackoffThrottling() has been called on this object. |
| bool is_backoff_disabled_; |
| |
| // Access it through GetBackoffEntry() to allow a unit test seam. |
| BackoffEntry backoff_entry_; |
| |
| // Weak back-reference to the manager object managing us. |
| URLRequestThrottlerManager* manager_; |
| |
| // Canonicalized URL string that this entry is for; used for logging only. |
| std::string url_id_; |
| |
| NetLogWithSource net_log_; |
| |
| DISALLOW_COPY_AND_ASSIGN(URLRequestThrottlerEntry); |
| }; |
| |
| } // namespace net |
| |
| #endif // NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_H_ |