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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #ifndef NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_H_ | |
| 6 #define NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_H_ | |
| 7 | |
| 8 #include <queue> | |
| 9 #include <string> | |
| 10 | |
| 11 #include "base/basictypes.h" | |
| 12 #include "base/time/time.h" | |
| 13 #include "net/base/backoff_entry.h" | |
| 14 #include "net/base/net_log.h" | |
| 15 #include "net/url_request/url_request_throttler_entry_interface.h" | |
| 16 | |
| 17 namespace net { | |
| 18 | |
| 19 class NetworkDelegate; | |
| 20 class URLRequestThrottlerManager; | |
| 21 | |
| 22 // URLRequestThrottlerEntry represents an entry of URLRequestThrottlerManager. | |
| 23 // It analyzes requests of a specific URL over some period of time, in order to | |
| 24 // deduce the back-off time for every request. | |
| 25 // The back-off algorithm consists of two parts. Firstly, exponential back-off | |
| 26 // is used when receiving 5XX server errors or malformed response bodies. | |
| 27 // The exponential back-off rule is enforced by URLRequestHttpJob. Any | |
| 28 // request sent during the back-off period will be cancelled. | |
| 29 // Secondly, a sliding window is used to count recent requests to a given | |
| 30 // destination and provide guidance (to the application level only) on whether | |
| 31 // too many requests have been sent and when a good time to send the next one | |
| 32 // would be. This is never used to deny requests at the network level. | |
| 33 class NET_EXPORT URLRequestThrottlerEntry | |
| 34 : public URLRequestThrottlerEntryInterface { | |
| 35 public: | |
| 36 // Sliding window period. | |
| 37 static const int kDefaultSlidingWindowPeriodMs; | |
| 38 | |
| 39 // Maximum number of requests allowed in sliding window period. | |
| 40 static const int kDefaultMaxSendThreshold; | |
| 41 | |
| 42 // Number of initial errors to ignore before starting exponential back-off. | |
| 43 static const int kDefaultNumErrorsToIgnore; | |
| 44 | |
| 45 // Initial delay for exponential back-off. | |
| 46 static const int kDefaultInitialDelayMs; | |
| 47 | |
| 48 // Factor by which the waiting time will be multiplied. | |
| 49 static const double kDefaultMultiplyFactor; | |
| 50 | |
| 51 // Fuzzing percentage. ex: 10% will spread requests randomly | |
| 52 // between 90%-100% of the calculated time. | |
| 53 static const double kDefaultJitterFactor; | |
| 54 | |
| 55 // Maximum amount of time we are willing to delay our request. | |
| 56 static const int kDefaultMaximumBackoffMs; | |
| 57 | |
| 58 // Time after which the entry is considered outdated. | |
| 59 static const int kDefaultEntryLifetimeMs; | |
| 60 | |
| 61 // Name of the header that sites can use to opt out of exponential back-off | |
| 62 // throttling. | |
| 63 static const char kExponentialThrottlingHeader[]; | |
| 64 | |
| 65 // Value for exponential throttling header that can be used to opt out of | |
| 66 // exponential back-off throttling. | |
| 67 static const char kExponentialThrottlingDisableValue[]; | |
| 68 | |
| 69 // The manager object's lifetime must enclose the lifetime of this object. | |
| 70 URLRequestThrottlerEntry(URLRequestThrottlerManager* manager, | |
| 71 const std::string& url_id); | |
| 72 | |
| 73 // The life span of instances created with this constructor is set to | |
| 74 // infinite, and the number of initial errors to ignore is set to 0. | |
| 75 // It is only used by unit tests. | |
| 76 URLRequestThrottlerEntry(URLRequestThrottlerManager* manager, | |
| 77 const std::string& url_id, | |
| 78 int sliding_window_period_ms, | |
| 79 int max_send_threshold, | |
| 80 int initial_backoff_ms, | |
| 81 double multiply_factor, | |
| 82 double jitter_factor, | |
| 83 int maximum_backoff_ms); | |
| 84 | |
| 85 // Used by the manager, returns true if the entry needs to be garbage | |
| 86 // collected. | |
| 87 bool IsEntryOutdated() const; | |
| 88 | |
| 89 // Causes this entry to never reject requests due to back-off. | |
| 90 void DisableBackoffThrottling(); | |
| 91 | |
| 92 // Causes this entry to NULL its manager pointer. | |
| 93 void DetachManager(); | |
| 94 | |
| 95 // Implementation of URLRequestThrottlerEntryInterface. | |
| 96 bool ShouldRejectRequest(const URLRequest& request, | |
| 97 NetworkDelegate* network_delegate) const override; | |
| 98 int64 ReserveSendingTimeForNextRequest( | |
| 99 const base::TimeTicks& earliest_time) override; | |
| 100 base::TimeTicks GetExponentialBackoffReleaseTime() const override; | |
| 101 void UpdateWithResponse( | |
| 102 const std::string& host, | |
| 103 const URLRequestThrottlerHeaderInterface* response) override; | |
| 104 void ReceivedContentWasMalformed(int response_code) override; | |
| 105 | |
| 106 protected: | |
| 107 ~URLRequestThrottlerEntry() override; | |
| 108 | |
| 109 void Initialize(); | |
| 110 | |
| 111 // Returns true if the given response code is considered an error for | |
| 112 // throttling purposes. | |
| 113 bool IsConsideredError(int response_code); | |
| 114 | |
| 115 // Equivalent to TimeTicks::Now(), virtual to be mockable for testing purpose. | |
| 116 virtual base::TimeTicks ImplGetTimeNow() const; | |
| 117 | |
| 118 // Used internally to handle the opt-out header. | |
| 119 void HandleThrottlingHeader(const std::string& header_value, | |
| 120 const std::string& host); | |
| 121 | |
| 122 // Retrieves the back-off entry object we're using. Used to enable a | |
| 123 // unit testing seam for dependency injection in tests. | |
| 124 virtual const BackoffEntry* GetBackoffEntry() const; | |
| 125 virtual BackoffEntry* GetBackoffEntry(); | |
| 126 | |
| 127 // Returns true if |load_flags| contains a flag that indicates an | |
| 128 // explicit request by the user to load the resource. We never | |
| 129 // throttle requests with such load flags. | |
| 130 static bool ExplicitUserRequest(const int load_flags); | |
| 131 | |
| 132 // Used by tests. | |
| 133 base::TimeTicks sliding_window_release_time() const { | |
| 134 return sliding_window_release_time_; | |
| 135 } | |
| 136 | |
| 137 // Used by tests. | |
| 138 void set_sliding_window_release_time(const base::TimeTicks& release_time) { | |
| 139 sliding_window_release_time_ = release_time; | |
| 140 } | |
| 141 | |
| 142 // Valid and immutable after construction time. | |
| 143 BackoffEntry::Policy backoff_policy_; | |
| 144 | |
| 145 private: | |
| 146 // Timestamp calculated by the sliding window algorithm for when we advise | |
| 147 // clients the next request should be made, at the earliest. Advisory only, | |
| 148 // not used to deny requests. | |
| 149 base::TimeTicks sliding_window_release_time_; | |
| 150 | |
| 151 // A list of the recent send events. We use them to decide whether there are | |
| 152 // too many requests sent in sliding window. | |
| 153 std::queue<base::TimeTicks> send_log_; | |
| 154 | |
| 155 const base::TimeDelta sliding_window_period_; | |
| 156 const int max_send_threshold_; | |
| 157 | |
| 158 // True if DisableBackoffThrottling() has been called on this object. | |
| 159 bool is_backoff_disabled_; | |
| 160 | |
| 161 // Access it through GetBackoffEntry() to allow a unit test seam. | |
| 162 BackoffEntry backoff_entry_; | |
| 163 | |
| 164 // Weak back-reference to the manager object managing us. | |
| 165 URLRequestThrottlerManager* manager_; | |
| 166 | |
| 167 // Canonicalized URL string that this entry is for; used for logging only. | |
| 168 std::string url_id_; | |
| 169 | |
| 170 BoundNetLog net_log_; | |
| 171 | |
| 172 DISALLOW_COPY_AND_ASSIGN(URLRequestThrottlerEntry); | |
| 173 }; | |
| 174 | |
| 175 } // namespace net | |
| 176 | |
| 177 #endif // NET_URL_REQUEST_URL_REQUEST_THROTTLER_ENTRY_H_ | |
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Chromium Code Reviews
Issue 992733002:
Remove //net (except for Android test stuff) and sdch (Closed)
Base URL: git@github.com:domokit/mojo.git@master