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// 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_PRERENDER_PRERENDER_TRACKER_H_
#define CHROME_BROWSER_PRERENDER_PRERENDER_TRACKER_H_
#include <map>
#include <set>
#include <utility>
#include <vector>
#include "base/gtest_prod_util.h"
#include "base/synchronization/lock.h"
#include "base/threading/non_thread_safe.h"
#include "chrome/browser/prerender/prerender_contents.h"
#include "chrome/browser/prerender/prerender_final_status.h"
#include "url/gurl.h"
namespace prerender {
class PrerenderManager;
struct RenderViewInfo;
// PrerenderTracker is responsible for keeping track of all prerendering
// RenderViews and their statuses. Its list is guaranteed to be up to date
// and can be modified on any thread.
class PrerenderTracker : public base::NonThreadSafe,
public PrerenderContents::Observer {
public:
PrerenderTracker();
virtual ~PrerenderTracker();
// Attempts to set the status of the specified RenderViewHost to
// FINAL_STATUS_USED. Returns true on success. Returns false if it has
// already been cancelled for any reason or is no longer prerendering.
// Can only be called only on the IO thread. This method will not call
// PrerenderContents::SetFinalStatus() on the corresponding PrerenderContents.
//
// If it returns true, all subsequent calls to TryCancel and TryUse for the
// RenderView will return false.
bool TryUse(int child_id, int route_id);
// Attempts to cancel prerendering by the specified RenderView, setting the
// FinalStatus to |final_status|. Returns true if the specified prerender has
// been cancelled, either as a result of this call or for any other reason.
// If the call results in cancelling a PrerenderContents, a task to destroy
// it is also posted to the UI thread.
//
// When true is returned, it is guaranteed that the RenderView will never
// be displayed. When false is returned, the RenderView has either been
// swapped into a tab or has already been destroyed.
bool TryCancel(int child_id, int route_id, FinalStatus final_status);
// Same as above, but can only called on the IO Thread. Does not acquire a
// lock when the RenderView is not being prerendered.
bool TryCancelOnIOThread(int child_id, int route_id,
FinalStatus final_status);
// Gets the FinalStatus of the specified prerendered RenderView. Returns
// |true| and sets |final_status| to the status of the RenderView if it
// is found, returns false otherwise.
bool GetFinalStatus(int child_id, int route_id,
FinalStatus* final_status) const;
// Returns whether or not a RenderView is prerendering. Can only be called on
// the IO thread. Does not acquire a lock, so may claim a RenderView that has
// been displayed or destroyed is still prerendering.
bool IsPrerenderingOnIOThread(int child_id, int route_id) const;
private:
friend class PrerenderContents;
FRIEND_TEST_ALL_PREFIXES(PrerenderTrackerTest, PrerenderTrackerNull);
FRIEND_TEST_ALL_PREFIXES(PrerenderTrackerTest, PrerenderTrackerUsed);
FRIEND_TEST_ALL_PREFIXES(PrerenderTrackerTest, PrerenderTrackerCancelled);
FRIEND_TEST_ALL_PREFIXES(PrerenderTrackerTest, PrerenderTrackerCancelledOnIO);
FRIEND_TEST_ALL_PREFIXES(PrerenderTrackerTest, PrerenderTrackerCancelledFast);
FRIEND_TEST_ALL_PREFIXES(PrerenderTrackerTest, PrerenderTrackerMultiple);
typedef std::pair<int, int> ChildRouteIdPair;
// Map of child/route id pairs to final statuses.
typedef std::map<ChildRouteIdPair, RenderViewInfo> FinalStatusMap;
// Set of child/route id pairs that may be prerendering.
typedef std::set<ChildRouteIdPair> PossiblyPrerenderingChildRouteIdPairs;
// From PrerenderContents::Observer:
virtual void OnPrerenderStart(PrerenderContents* prerender_contents) OVERRIDE;
virtual void OnPrerenderStop(PrerenderContents* prerender_contents) OVERRIDE;
// Attempts to set the FinalStatus of the specified RenderView to
// |desired_final_status|. If non-NULL, |actual_final_status| is set to the
// FinalStatus of the RenderView.
//
// If the FinalStatus of the RenderView is successfully set, returns true and
// sets |actual_final_status| to |desired_final_status|.
//
// If the FinalStatus of the RenderView was already set, returns false and
// sets |actual_final_status| to the actual FinalStatus of the RenderView.
//
// If the RenderView is not a prerendering RenderView, returns false and sets
// |actual_final_status| to FINAL_STATUS_MAX.
bool SetFinalStatus(int child_id, int route_id,
FinalStatus desired_final_status,
FinalStatus* actual_final_status);
// Add/remove the specified pair to |possibly_prerendering_io_thread_set_| on
// the IO Thread.
void AddPrerenderOnIOThread(const ChildRouteIdPair& child_route_id_pair);
void RemovePrerenderOnIOThread(const ChildRouteIdPair& child_route_id_pair);
// Tasks posted to the IO Thread to call the above functions.
static void AddPrerenderOnIOThreadTask(
const ChildRouteIdPair& child_route_id_pair);
static void RemovePrerenderOnIOThreadTask(
const ChildRouteIdPair& child_route_id_pair);
static PrerenderTracker* GetDefault();
// |final_status_map_lock_| protects access to |final_status_map_|.
mutable base::Lock final_status_map_lock_;
// Map containing child/route id pairs and their final statuses. Must only be
// accessed while the lock is held. Values are always accurate and up to
// date.
FinalStatusMap final_status_map_;
// Superset of child/route id pairs that are prerendering. Can only access on
// the IO thread. May contain entries that have since been displayed. Only
// used to prevent locking when not needed.
PossiblyPrerenderingChildRouteIdPairs possibly_prerendering_io_thread_set_;
DISALLOW_COPY_AND_ASSIGN(PrerenderTracker);
};
} // namespace prerender
#endif // CHROME_BROWSER_PRERENDER_PRERENDER_TRACKER_H_
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