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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 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 | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef CHROME_BROWSER_EXTENSIONS_UPDATER_REQUEST_QUEUE_H_ | 5 #ifndef EXTENSIONS_BROWSER_UPDATER_REQUEST_QUEUE_H_ |
6 #define CHROME_BROWSER_EXTENSIONS_UPDATER_REQUEST_QUEUE_H_ | 6 #define EXTENSIONS_BROWSER_UPDATER_REQUEST_QUEUE_H_ |
7 | 7 |
8 #include <deque> | 8 #include <deque> |
9 #include <utility> | 9 #include <utility> |
10 | 10 |
11 #include "base/callback.h" | 11 #include "base/callback.h" |
12 #include "base/memory/linked_ptr.h" | 12 #include "base/memory/linked_ptr.h" |
13 #include "base/memory/scoped_ptr.h" | 13 #include "base/memory/scoped_ptr.h" |
14 #include "base/time/time.h" | 14 #include "base/time/time.h" |
15 #include "base/timer/timer.h" | 15 #include "base/timer/timer.h" |
16 #include "net/base/backoff_entry.h" | 16 #include "net/base/backoff_entry.h" |
17 | 17 |
18 namespace extensions { | 18 namespace extensions { |
19 | 19 |
20 // This class keeps track of a queue of requests, and contains the logic to | 20 // This class keeps track of a queue of requests, and contains the logic to |
21 // retry requests with some backoff policy. Each request has a | 21 // retry requests with some backoff policy. Each request has a |
22 // net::BackoffEntry instance associated with it. | 22 // net::BackoffEntry instance associated with it. |
23 // | 23 // |
24 // The general flow when using this class would be something like this: | 24 // The general flow when using this class would be something like this: |
25 // - requests are queued up by calling ScheduleRequest. | 25 // - requests are queued up by calling ScheduleRequest. |
26 // - when a request is ready to be executed, RequestQueue removes the | 26 // - when a request is ready to be executed, RequestQueue removes the |
27 // request from the queue, assigns it as active request, and calls | 27 // request from the queue, assigns it as active request, and calls |
28 // the callback that was passed to the constructor. | 28 // the callback that was passed to the constructor. |
29 // - (optionally) when a request has completed unsuccessfully call | 29 // - (optionally) when a request has completed unsuccessfully call |
30 // RetryRequest to put the request back in the queue, using the | 30 // RetryRequest to put the request back in the queue, using the |
31 // backoff policy and minimum backoff delay to determine when to | 31 // backoff policy and minimum backoff delay to determine when to |
32 // next schedule this request. | 32 // next schedule this request. |
33 // - call reset_active_request() to indicate that the active request has | 33 // - call reset_active_request() to indicate that the active request has |
34 // been dealt with. | 34 // been dealt with. |
35 // - call StartNextRequest to schedule the next pending request (if any). | 35 // - call StartNextRequest to schedule the next pending request (if any). |
36 template<typename T> | 36 template <typename T> |
37 class RequestQueue { | 37 class RequestQueue { |
38 public: | 38 public: |
39 class iterator; | 39 class iterator; |
40 | 40 |
41 RequestQueue(const net::BackoffEntry::Policy* backoff_policy, | 41 RequestQueue(const net::BackoffEntry::Policy* backoff_policy, |
42 const base::Closure& start_request_callback); | 42 const base::Closure& start_request_callback); |
43 ~RequestQueue(); | 43 ~RequestQueue(); |
44 | 44 |
45 // Returns the request that is currently being processed. | 45 // Returns the request that is currently being processed. |
46 T* active_request(); | 46 T* active_request(); |
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81 | 81 |
82 private: | 82 private: |
83 struct Request { | 83 struct Request { |
84 Request(net::BackoffEntry* backoff_entry, T* request) | 84 Request(net::BackoffEntry* backoff_entry, T* request) |
85 : backoff_entry(backoff_entry), request(request) {} | 85 : backoff_entry(backoff_entry), request(request) {} |
86 linked_ptr<net::BackoffEntry> backoff_entry; | 86 linked_ptr<net::BackoffEntry> backoff_entry; |
87 linked_ptr<T> request; | 87 linked_ptr<T> request; |
88 }; | 88 }; |
89 | 89 |
90 // Compares the release time of two pending requests. | 90 // Compares the release time of two pending requests. |
91 static bool CompareRequests(const Request& a, | 91 static bool CompareRequests(const Request& a, const Request& b); |
92 const Request& b); | |
93 | 92 |
94 // Pushes a request with a given backoff entry onto the queue. | 93 // Pushes a request with a given backoff entry onto the queue. |
95 void PushImpl(scoped_ptr<T> request, | 94 void PushImpl(scoped_ptr<T> request, |
96 scoped_ptr<net::BackoffEntry> backoff_entry); | 95 scoped_ptr<net::BackoffEntry> backoff_entry); |
97 | 96 |
98 // The backoff policy used to determine backoff delays. | 97 // The backoff policy used to determine backoff delays. |
99 const net::BackoffEntry::Policy* backoff_policy_; | 98 const net::BackoffEntry::Policy* backoff_policy_; |
100 | 99 |
101 // Callback to call when a new request has become the active request. | 100 // Callback to call when a new request has become the active request. |
102 base::Closure start_request_callback_; | 101 base::Closure start_request_callback_; |
103 | 102 |
104 // Priority queue of pending requests. Not using std::priority_queue since | 103 // Priority queue of pending requests. Not using std::priority_queue since |
105 // the code needs to be able to iterate over all pending requests. | 104 // the code needs to be able to iterate over all pending requests. |
106 std::deque<Request> pending_requests_; | 105 std::deque<Request> pending_requests_; |
107 | 106 |
108 // Active request and its associated backoff entry. | 107 // Active request and its associated backoff entry. |
109 scoped_ptr<T> active_request_; | 108 scoped_ptr<T> active_request_; |
110 scoped_ptr<net::BackoffEntry> active_backoff_entry_; | 109 scoped_ptr<net::BackoffEntry> active_backoff_entry_; |
111 | 110 |
112 // Timer to schedule calls to StartNextRequest, if the first pending request | 111 // Timer to schedule calls to StartNextRequest, if the first pending request |
113 // hasn't passed its release time yet. | 112 // hasn't passed its release time yet. |
114 base::Timer timer_; | 113 base::Timer timer_; |
115 }; | 114 }; |
116 | 115 |
117 // Iterator class that wraps a std::deque<> iterator, only giving access to the | 116 // Iterator class that wraps a std::deque<> iterator, only giving access to the |
118 // actual request part of each item. | 117 // actual request part of each item. |
119 template<typename T> | 118 template <typename T> |
120 class RequestQueue<T>::iterator { | 119 class RequestQueue<T>::iterator { |
121 public: | 120 public: |
122 iterator() {} | 121 iterator() {} |
123 | 122 |
124 T* operator*() { return it_->request.get(); } | 123 T* operator*() { return it_->request.get(); } |
125 T* operator->() { return it_->request.get(); } | 124 T* operator->() { return it_->request.get(); } |
126 iterator& operator++() { | 125 iterator& operator++() { |
127 ++it_; | 126 ++it_; |
128 return *this; | 127 return *this; |
129 } | 128 } |
130 bool operator!=(const iterator& b) const { | 129 bool operator!=(const iterator& b) const { return it_ != b.it_; } |
131 return it_ != b.it_; | |
132 } | |
133 | 130 |
134 private: | 131 private: |
135 friend class RequestQueue<T>; | 132 friend class RequestQueue<T>; |
136 typedef std::deque<typename RequestQueue<T>::Request> Container; | 133 typedef std::deque<typename RequestQueue<T>::Request> Container; |
137 | 134 |
138 explicit iterator(const typename Container::iterator& it) | 135 explicit iterator(const typename Container::iterator& it) : it_(it) {} |
139 : it_(it) {} | |
140 | 136 |
141 typename Container::iterator it_; | 137 typename Container::iterator it_; |
142 }; | 138 }; |
143 | 139 |
144 | |
145 } // namespace extensions | 140 } // namespace extensions |
146 | 141 |
147 #endif // CHROME_BROWSER_EXTENSIONS_UPDATER_REQUEST_QUEUE_H_ | 142 #endif // EXTENSIONS_BROWSER_UPDATER_REQUEST_QUEUE_H_ |
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