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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 | |
13 class GURL; | |
14 struct ResourceHostMsg_Request; | |
15 | |
16 namespace net { | |
17 class URLRequest; | |
18 class HttpCache; | |
19 } | |
20 | |
21 namespace content { | |
22 | |
23 class AsyncRevalidationDriver; | |
24 class ResourceContext; | |
25 class ResourceScheduler; | |
26 | |
27 // This class manages all active AsyncRevalidationDriver objects for the whole | |
28 // process. It also implements the creation of a new net::URLRequest and | |
29 // AsyncRevalidationDriver from an existing net::URLRequest that has had the | |
30 // stale-while-revalidate algorithm applied to it. | |
31 class AsyncRevalidationManager { | |
32 public: | |
33 AsyncRevalidationManager(); | |
34 ~AsyncRevalidationManager(); | |
35 | |
36 // Starts an async revalidation by copying |for_request|. |scheduler| must | |
37 // remain valid until this object is destroyed. | |
38 void BeginAsyncRevalidation(net::URLRequest* for_request, | |
39 ResourceScheduler* scheduler); | |
40 | |
41 // Cancel all pending async revalidations that use ResourceContext. | |
42 void CancelAsyncRevalidationsForResourceContext( | |
43 ResourceContext* resource_context); | |
44 | |
45 static bool QualifiesForAsyncRevalidation( | |
46 const ResourceHostMsg_Request& request); | |
47 | |
48 private: | |
49 // The key used to lookup an AsyncRevalidationDriver in the map of pending | |
Bence
2015/11/17 13:12:23
Optional: feel free to remove "used to lookup". I
Adam Rice
2015/11/17 17:45:53
Done.
| |
50 // async revalidations. This key has a | |
51 // distinct value for every in-progress async revalidation. It is used to | |
52 // avoid | |
53 // duplicate async revalidations, and also to cancel affected async | |
54 // revalidations when a ResourceContext is removed. | |
55 // Request headers are intentionally not included in the key as they usually | |
56 // don't affect caching, and could cause effectively identical revalidations | |
57 // to be considered different because they have a different "Referer" | |
58 // header. In rare cases where a "Vary" header leads to us to access different | |
59 // resources at the same URL, they fight a single cache slot and so performing | |
60 // additional async revalidations will not improve matters. | |
Bence
2015/11/17 13:12:23
Please reflow this paragraph.
Adam Rice
2015/11/17 17:45:53
Done.
| |
61 struct AsyncRevalidationKey { | |
62 AsyncRevalidationKey(const ResourceContext* resource_context, | |
63 const net::HttpCache* http_cache, | |
64 const GURL& url); | |
65 | |
66 // Create a prefix key that is used to match all of the | |
67 // AsyncRevalidationDrivers using |resource_context| in the map. | |
68 explicit AsyncRevalidationKey(const ResourceContext* resource_context); | |
69 | |
70 // The key for a map needs to be copyable. | |
71 AsyncRevalidationKey(const AsyncRevalidationKey& rhs) = default; | |
72 ~AsyncRevalidationKey(); | |
73 | |
74 // No operator= is generated because the struct members are immutable. | |
75 | |
76 // |resource_context| and |http_cache| are never dereferenced; they are only | |
77 // compared to other values. In order to efficiently find and delete all | |
78 // in-progress async revalidations using a particular ResourceContext, it | |
79 // forms the first part of the key. | |
Bence
2015/11/17 13:12:23
This last sentence might be more appropriate as a
Adam Rice
2015/11/17 17:45:52
I think you're right. I have removed the implement
| |
80 const ResourceContext* const resource_context; | |
81 | |
82 // Each ResourceContext owns one or more HttpCache objects. | |
Bence
2015/11/17 13:12:23
Optional: write "There might be multiple HttpCache
Adam Rice
2015/11/17 17:45:53
Sorry about that. I changed it to "There are multi
Bence
2015/11/17 21:34:28
Splendid.
| |
83 const net::HttpCache* const http_cache; | |
84 | |
85 // Derived from the url via net::HttpUtil::SpecForRequest(). | |
86 const std::string url_key; | |
87 | |
88 struct LessThan { | |
89 bool operator()(const AsyncRevalidationKey& lhs, | |
90 const AsyncRevalidationKey& rhs) const; | |
91 }; | |
92 }; | |
93 | |
94 // Map of AsyncRevalidationDriver object. | |
Bence
2015/11/17 13:12:23
Optional: remove this comment, fold into the one b
Adam Rice
2015/11/17 17:45:53
Done.
| |
95 typedef std::map<AsyncRevalidationKey, | |
Bence
2015/11/17 13:12:23
Use "using" instead of "typedef", see https://chro
Adam Rice
2015/11/17 17:45:53
Thanks. Old habits die hard.
| |
96 AsyncRevalidationDriver*, | |
97 AsyncRevalidationKey::LessThan> AsyncRevalidationMap; | |
98 | |
99 void OnAsyncRevalidationComplete(AsyncRevalidationMap::iterator it); | |
100 | |
101 // Async revalidations that are currently in-flight: either waiting to be | |
Bence
2015/11/17 13:12:23
Optional: "AsyncRevalidationDriver instances that
Adam Rice
2015/11/17 17:45:53
Done.
| |
102 // scheduled or active on the network. | |
103 AsyncRevalidationMap in_progress_; | |
104 | |
105 DISALLOW_COPY_AND_ASSIGN(AsyncRevalidationManager); | |
106 }; | |
107 | |
108 } // namespace content | |
109 | |
110 #endif // CONTENT_BROWSER_LOADER_ASYNC_REVALIDATION_MANAGER_H_ | |
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