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1 // Copyright 2015 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 CONTENT_BROWSER_LOADER_ASYNC_REVALIDATION_MANAGER_H_ | |
6 #define CONTENT_BROWSER_LOADER_ASYNC_REVALIDATION_MANAGER_H_ | |
7 | |
8 #include <map> | |
9 #include <string> | |
10 | |
11 #include "base/macros.h" | |
12 #include "base/memory/scoped_ptr.h" | |
13 | |
14 class GURL; | |
15 struct ResourceHostMsg_Request; | |
16 | |
17 namespace net { | |
18 class URLRequest; | |
19 class HttpCache; | |
20 } | |
21 | |
22 namespace content { | |
23 | |
24 class AsyncRevalidationDriver; | |
25 class ResourceContext; | |
26 class ResourceScheduler; | |
27 | |
28 // One instance of this class manages all active AsyncRevalidationDriver objects | |
29 // for all profiles. It is created by and owned by | |
30 // ResourceDispatcherHostImpl. It also implements the creation of a new | |
31 // net::URLRequest and AsyncRevalidationDriver from an existing net::URLRequest | |
32 // that has had the stale-while-revalidate algorithm applied to it. | |
33 class AsyncRevalidationManager { | |
34 public: | |
35 AsyncRevalidationManager(); | |
36 ~AsyncRevalidationManager(); | |
37 | |
38 // Starts an async revalidation by copying |for_request|. |scheduler| must | |
39 // remain valid until this object is destroyed. | |
40 void BeginAsyncRevalidation(const net::URLRequest& for_request, | |
41 ResourceScheduler* scheduler); | |
42 | |
43 // Cancel all pending async revalidations that use ResourceContext. | |
44 void CancelAsyncRevalidationsForResourceContext( | |
45 ResourceContext* resource_context); | |
46 | |
47 static bool QualifiesForAsyncRevalidation( | |
48 const ResourceHostMsg_Request& request); | |
49 | |
50 private: | |
51 // The key of the map of pending async revalidations. This key has a distinct | |
52 // value for every in-progress async revalidation. It is used to avoid | |
53 // duplicate async revalidations, and also to cancel affected async | |
54 // revalidations when a ResourceContext is removed. | |
55 // | |
56 // Request headers are intentionally not included in the key as they usually | |
57 // don't affect caching, and could cause effectively identical revalidations | |
58 // to be considered different because they have a different "Referer" | |
59 // header. In rare cases where a "Vary" header leads to us to access different | |
60 // resources at the same URL, they fight over a single cache slot and so | |
61 // performing additional async revalidations will not improve matters. | |
davidben
2015/12/07 23:56:04
Nit: This comment assumes net::HttpCache won't eve
Adam Rice
2015/12/08 18:05:35
I filed a bug for it and added a link.
| |
62 struct AsyncRevalidationKey { | |
63 AsyncRevalidationKey(const ResourceContext* resource_context, | |
64 const net::HttpCache* http_cache, | |
65 const GURL& url); | |
66 | |
67 // Create a prefix key that is used to match all of the | |
68 // AsyncRevalidationDrivers using |resource_context| in the map. | |
69 explicit AsyncRevalidationKey(const ResourceContext* resource_context); | |
70 | |
71 // The key for a map needs to be copyable. | |
72 AsyncRevalidationKey(const AsyncRevalidationKey& rhs) = default; | |
73 ~AsyncRevalidationKey(); | |
74 | |
75 // No operator= is generated because the struct members are immutable. | |
76 | |
77 // |resource_context| and |http_cache| are never dereferenced; they are only | |
78 // compared to other values. | |
79 const ResourceContext* const resource_context; | |
80 | |
81 // There are multiple independent HttpCache objects per ResourceContext. | |
82 const net::HttpCache* const http_cache; | |
83 | |
84 // Derived from the url via net::HttpUtil::SpecForRequest(). | |
85 const std::string url_key; | |
86 | |
87 struct LessThan { | |
88 bool operator()(const AsyncRevalidationKey& lhs, | |
89 const AsyncRevalidationKey& rhs) const; | |
90 }; | |
91 }; | |
92 | |
93 using AsyncRevalidationMap = std::map<AsyncRevalidationKey, | |
94 scoped_ptr<AsyncRevalidationDriver>, | |
95 AsyncRevalidationKey::LessThan>; | |
96 | |
97 void OnAsyncRevalidationComplete(AsyncRevalidationMap::iterator it); | |
98 | |
99 // Map of AsyncRevalidationDriver instances that are currently in-flight: | |
100 // either waiting to be scheduled or active on the network. | |
101 AsyncRevalidationMap in_progress_; | |
102 | |
103 DISALLOW_COPY_AND_ASSIGN(AsyncRevalidationManager); | |
104 }; | |
105 | |
106 } // namespace content | |
107 | |
108 #endif // CONTENT_BROWSER_LOADER_ASYNC_REVALIDATION_MANAGER_H_ | |
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