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// Copyright (c) 2011 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_NET_CONNECT_INTERCEPTOR_H_
#define CHROME_BROWSER_NET_CONNECT_INTERCEPTOR_H_
#include "base/containers/mru_cache.h"
#include "base/gtest_prod_util.h"
#include "base/memory/scoped_ptr.h"
#include "base/time.h"
class GURL;
namespace net {
class URLRequest;
}
namespace chrome_browser_net {
class Predictor;
//------------------------------------------------------------------------------
// An interceptor to monitor URLRequests so that we can do speculative DNS
// resolution and/or speculative TCP preconnections.
class ConnectInterceptor {
public:
// Construction includes registration as an URL.
explicit ConnectInterceptor(Predictor* predictor);
// Destruction includes unregistering.
virtual ~ConnectInterceptor();
// Learn about referrers, and optionally preconnect based on history.
void WitnessURLRequest(net::URLRequest* request) const;
private:
// Provide access to local class TimedCache for testing.
FRIEND_TEST_ALL_PREFIXES(ConnectInterceptorTest, TimedCacheRecall);
FRIEND_TEST_ALL_PREFIXES(ConnectInterceptorTest, TimedCacheEviction);
// Define a LRU cache that recalls all navigations within the last N seconds.
// When we learn about subresources to possibly preconnect to, it would be a
// waste to preconnect when the original navigation was too long ago. Any
// connected, but unused TCP/IP connection, will generally be reset by the
// server if it is not used quickly (i.e., GET or POST is sent).
class TimedCache {
public:
explicit TimedCache(const base::TimeDelta& max_duration);
~TimedCache();
// Evicts any entries that have been in the FIFO "too long," and then checks
// to see if the given url is (still) in the FIFO cache.
bool WasRecentlySeen(const GURL& url) const;
// Adds the given url to the cache, where it will remain for max_duration_.
void SetRecentlySeen(const GURL& url) const;
private:
// Our cache will be keyed on a URL (actually, just a scheme/host/port).
// We will always track the time it was last added to the FIFO cache by
// remembering a TimeTicks value.
typedef base::MRUCache<GURL, base::TimeTicks> UrlMruTimedCache;
// mru_cache_ has to be mutable in order to be accessed from the overriden
// URLRequestJob functions. It is mutable because it tracks the urls and
// caches them.
mutable UrlMruTimedCache mru_cache_;
// The longest time an entry can persist in the cache, and still be found.
const base::TimeDelta max_duration_;
DISALLOW_COPY_AND_ASSIGN(TimedCache);
};
TimedCache timed_cache_;
Predictor* const predictor_;
DISALLOW_COPY_AND_ASSIGN(ConnectInterceptor);
};
} // namespace chrome_browser_net
#endif // CHROME_BROWSER_NET_CONNECT_INTERCEPTOR_H_
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