// 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 CHROME_BROWSER_HISTORY_TOP_SITES_CACHE_H_
#define CHROME_BROWSER_HISTORY_TOP_SITES_CACHE_H_
#include <map>
#include <utility>
#include "base/memory/ref_counted.h"
#include "chrome/browser/history/history_types.h"
#include "chrome/browser/history/url_utils.h"
#include "url/gurl.h"
class GURL;
namespace history {
// TopSiteCache caches thumbnails for visited pages. 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.
// TopSitesCache caches the top sites and thumbnails for TopSites.
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_; }
// 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 // CHROME_BROWSER_HISTORY_TOP_SITES_CACHE_H_