1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
// 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 COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_CACHE_H_
#define COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_CACHE_H_
#include <stddef.h>
#include <map>
#include <utility>
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "components/history/core/browser/history_types.h"
#include "components/history/core/browser/url_utils.h"
#include "url/gurl.h"
namespace history {
// TopSitesCache caches the top sites and thumbnails for TopSites.
//
// Retrieving thumbnails from a given input URL is a two-stage process:
//
// input URL --(map 1)--> canonical URL --(map 2)--> image.
//
// (map 1) searches for an URL in |canonical_urls_| that "matches" (see below)
// input URL. If found, canonical URL assigned to the result. Otherwise the
// input URL is considered to already be a canonical URL.
//
// (map 2) simply looks up canonical URL in |images_|.
//
// The rule to "match" URL in |canonical_urls_| always favors exact match.
// - In GetCanonicalURL(), exact match is the only case examined.
// - In GetGeneralizedCanonicalURL(), we also perform "generalized" URL matches,
// i.e., stored URLs in |canonical_urls_| that are prefixes of input URL,
// ignoring "?query#ref".
// For the latter two "URL prefix matches", we prefer the match that is closest
// to input URL, w.r.t. path hierarchy.
class TopSitesCache {
public:
TopSitesCache();
~TopSitesCache();
// Set the top sites. In |top_sites| all forced URLs must appear before
// non-forced URLs. This is only checked in debug.
void SetTopSites(const MostVisitedURLList& top_sites);
const MostVisitedURLList& top_sites() const { return top_sites_; }
// The thumbnails.
void SetThumbnails(const URLToImagesMap& images);
const URLToImagesMap& images() const { return images_; }
void ClearUnreferencedThumbnails();
// Returns the thumbnail as an Image for the specified url. This adds an entry
// for |url| if one has not yet been added.
Images* GetImage(const GURL& url);
// Fetches the thumbnail for the specified url. Returns true if there is a
// thumbnail for the specified url. It is possible for a URL to be in TopSites
// but not have an thumbnail.
bool GetPageThumbnail(const GURL& url,
scoped_refptr<base::RefCountedMemory>* bytes) const;
// Fetches the thumbnail score for the specified url. Returns true if
// there is a thumbnail score for the specified url.
bool GetPageThumbnailScore(const GURL& url, ThumbnailScore* score) const;
// Returns the canonical URL for |url|.
const GURL& GetCanonicalURL(const GURL& url) const;
// Searches for a URL in |canonical_urls_| that is a URL prefix of |url|.
// Prefers an exact match if it exists, or the least generalized match while
// ignoring "?query#ref". Returns the resulting canonical URL if match is
// found, otherwise returns an empty GURL.
GURL GetGeneralizedCanonicalURL(const GURL& url) const;
// Returns true if |url| is known.
bool IsKnownURL(const GURL& url) const;
// Returns the index into |top_sites_| for |url|.
size_t GetURLIndex(const GURL& url) const;
// Returns the number of non-forced URLs in the cache.
size_t GetNumNonForcedURLs() const;
// Returns the number of forced URLs in the cache.
size_t GetNumForcedURLs() const;
private:
// The entries in CanonicalURLs, see CanonicalURLs for details. The second
// argument gives the index of the URL into MostVisitedURLs redirects.
typedef std::pair<MostVisitedURL*, size_t> CanonicalURLEntry;
// Comparator used for CanonicalURLs.
class CanonicalURLComparator {
public:
bool operator()(const CanonicalURLEntry& e1,
const CanonicalURLEntry& e2) const {
return CanonicalURLStringCompare(e1.first->redirects[e1.second].spec(),
e2.first->redirects[e2.second].spec());
}
};
// Creates the object needed to form std::map queries into |canonical_urls_|,
// wrapping all required temporary data to allow inlining.
class CanonicalURLQuery {
public:
explicit CanonicalURLQuery(const GURL& url);
~CanonicalURLQuery();
const CanonicalURLEntry& entry() { return entry_; }
private:
MostVisitedURL most_visited_url_;
CanonicalURLEntry entry_;
};
// This is used to map from redirect url to the MostVisitedURL the redirect is
// from. Ideally this would be map<GURL, size_t> (second param indexing into
// top_sites_), but this results in duplicating all redirect urls. As some
// sites have a lot of redirects, we instead use the MostVisitedURL* and the
// index of the redirect as the key, and the index into top_sites_ as the
// value. This way we aren't duplicating GURLs. CanonicalURLComparator
// enforces the ordering as if we were using GURLs.
typedef std::map<CanonicalURLEntry, size_t,
CanonicalURLComparator> CanonicalURLs;
// Count the number of forced URLs.
void CountForcedURLs();
// Generates the set of canonical urls from |top_sites_|.
void GenerateCanonicalURLs();
// Stores a set of redirects. This is used by GenerateCanonicalURLs.
void StoreRedirectChain(const RedirectList& redirects, size_t destination);
// Returns the iterator into |canonical_urls_| for the |url|.
CanonicalURLs::const_iterator GetCanonicalURLsIterator(const GURL& url) const;
// Returns the GURL corresponding to an iterator in |canonical_urls_|.
const GURL& GetURLFromIterator(CanonicalURLs::const_iterator it) const;
// The number of top sites with forced URLs.
size_t num_forced_urls_;
// The top sites. This list must always contain the forced URLs first followed
// by the non-forced URLs. This is not strictly enforced but is checked in
// debug.
MostVisitedURLList top_sites_;
// The images. These map from canonical url to image.
URLToImagesMap images_;
// Generated from the redirects to and from the most visited pages. See
// description above typedef for details.
CanonicalURLs canonical_urls_;
// Helper to clear "?query#ref" from any GURL. This is set in the constructor
// and never modified after.
GURL::Replacements clear_query_ref_;
// Helper to clear "/path?query#ref" from any GURL. This is set in the
// constructor and never modified after.
GURL::Replacements clear_path_query_ref_;
DISALLOW_COPY_AND_ASSIGN(TopSitesCache);
};
} // namespace history
#endif // COMPONENTS_HISTORY_CORE_BROWSER_TOP_SITES_CACHE_H_
|
