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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_PRERENDER_PRERENDER_MANAGER_H_
#define CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
#pragma once
#include <list>
#include <vector>
#include "base/ref_counted.h"
#include "base/scoped_ptr.h"
#include "base/time.h"
#include "chrome/browser/prerender/prerender_contents.h"
#include "googleurl/src/gurl.h"
class Profile;
class TabContents;
namespace prerender {
// PrerenderManager is responsible for initiating and keeping prerendered
// views of webpages.
class PrerenderManager : public base::RefCounted<PrerenderManager> {
public:
// PrerenderManagerMode is used in a UMA_HISTOGRAM, so please do not
// add in the middle.
enum PrerenderManagerMode {
PRERENDER_MODE_DISABLED,
PRERENDER_MODE_ENABLED,
PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP,
PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP,
PRERENDER_MODE_MAX
};
// Owned by a Profile object for the lifetime of the profile.
explicit PrerenderManager(Profile* profile);
// Preloads the URL supplied. alias_urls indicates URLs that redirect
// to the same URL to be preloaded. Returns true if the URL was added,
// false if it was not.
bool AddPreload(const GURL& url, const std::vector<GURL>& alias_urls,
const GURL& referrer);
// For a given TabContents that wants to navigate to the URL supplied,
// determines whether a preloaded version of the URL can be used,
// and substitutes the prerendered RVH into the TabContents. Returns
// whether or not a prerendered RVH could be used or not.
bool MaybeUsePreloadedPage(TabContents* tc, const GURL& url);
// Allows PrerenderContents to remove itself when prerendering should
// be cancelled.
void RemoveEntry(PrerenderContents* entry);
// Retrieves the PrerenderContents object for the specified URL, if it
// has been prerendered. The caller will then have ownership of the
// PrerenderContents object and is responsible for freeing it.
// Returns NULL if the specified URL has not been prerendered.
PrerenderContents* GetEntry(const GURL& url);
// The following two methods should only be called from the UI thread.
void RecordPerceivedPageLoadTime(base::TimeDelta pplt);
void RecordTimeUntilUsed(base::TimeDelta time_until_used);
base::TimeDelta max_prerender_age() const { return max_prerender_age_; }
void set_max_prerender_age(base::TimeDelta td) { max_prerender_age_ = td; }
unsigned int max_elements() const { return max_elements_; }
void set_max_elements(unsigned int num) { max_elements_ = num; }
static PrerenderManagerMode GetMode();
static void SetMode(PrerenderManagerMode mode);
static bool IsPrerenderingEnabled();
// The following static method can be called from any thread, but will result
// in posting a task to the UI thread if we are not in the UI thread.
static void RecordPrefetchTagObserved();
protected:
virtual ~PrerenderManager();
void SetPrerenderContentsFactory(
PrerenderContents::Factory* prerender_contents_factory);
private:
// Test that needs needs access to internal functions.
friend class PrerenderBrowserTest;
friend class base::RefCounted<PrerenderManager>;
struct PrerenderContentsData;
// Starts and stops scheduling periodic cleanups, respectively.
void StartSchedulingPeriodicCleanups();
void StopSchedulingPeriodicCleanups();
// Schedules a periodic cleanup.
void SchedulePeriodicCleanup();
// Deletes stale prerendered PrerenderContents.
// Also identifies and kills PrerenderContents that use too much
// resources.
void PeriodicCleanup();
bool IsPrerenderElementFresh(const base::Time start) const;
void DeleteOldEntries();
virtual base::Time GetCurrentTime() const;
virtual PrerenderContents* CreatePrerenderContents(
const GURL& url,
const std::vector<GURL>& alias_urls,
const GURL& referrer);
// Finds the specified PrerenderContents and returns it, if it exists.
// Returns NULL otherwise. Unlike GetEntry, the PrerenderManager maintains
// ownership of the PrerenderContents.
PrerenderContents* FindEntry(const GURL& url);
bool ShouldRecordWindowedPPLT() const;
static void RecordPrefetchTagObservedOnUIThread();
Profile* profile_;
base::TimeDelta max_prerender_age_;
unsigned int max_elements_;
// List of prerendered elements.
std::list<PrerenderContentsData> prerender_list_;
// Default maximum permitted elements to prerender.
static const unsigned int kDefaultMaxPrerenderElements = 1;
// Default maximum age a prerendered element may have, in seconds.
static const int kDefaultMaxPrerenderAgeSeconds = 20;
// Time window for which we will record windowed PLT's from the last
// observed link rel=prefetch tag.
static const int kWindowedPPLTSeconds = 30;
// Time interval at which periodic cleanups are performed.
static const int kPeriodicCleanupIntervalMs = 1000;
scoped_ptr<PrerenderContents::Factory> prerender_contents_factory_;
static PrerenderManagerMode mode_;
// The time when we last saw a prefetch request coming from a renderer.
// This is used to record perceived PLT's for a certain amount of time
// from the point that we last saw a <link rel=prefetch> tag.
// This static variable should only be modified on the UI thread.
static base::TimeTicks last_prefetch_seen_time_;
// Indicates whether we are currently performing periodic cleanups
// of pending prerendered pages.
bool periodic_cleanups_active_;
DISALLOW_COPY_AND_ASSIGN(PrerenderManager);
};
} // prerender
#endif // CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
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