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// Copyright (c) 2006-2008 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_BROWSING_INSTANCE_H__
#define CHROME_BROWSER_BROWSING_INSTANCE_H__
#include "base/hash_tables.h"
#include "chrome/browser/profile.h"
#include "googleurl/src/gurl.h"
class SiteInstance;
///////////////////////////////////////////////////////////////////////////////
//
// BrowsingInstance class
//
// A browsing instance corresponds to the notion of a "unit of related browsing
// contexts" in the HTML 5 spec. Intuitively, it represents a collection of
// tabs and frames that can have script connections to each other. In that
// sense, it reflects the user interface, and not the contents of the tabs and
// frames.
//
// We further subdivide a BrowsingInstance into SiteInstances, which represent
// the documents within each BrowsingInstance that are from the same site and
// thus can have script access to each other. Different SiteInstances can
// safely run in different processes, because their documents cannot access
// each other's contents (due to the same origin policy).
//
// It is important to only have one SiteInstance per site within a given
// BrowsingInstance. This is because any two documents from the same site
// might be able to script each other if they are in the same BrowsingInstance.
// Thus, they must be rendered in the same process.
//
// If the process-per-site model is in use, then we ensure that there is only
// one SiteInstance per site for the entire profile, not just for each
// BrowsingInstance. This reduces the number of renderer processes we create.
// (This is currently only true if --process-per-site is specified at the
// command line.)
//
// A BrowsingInstance is live as long as any SiteInstance has a reference to
// it. A SiteInstance is live as long as any NavigationEntry or RenderViewHost
// have references to it. Because both classes are RefCounted, they do not
// need to be manually deleted.
//
// Currently, the BrowsingInstance class is not visible outside of the
// SiteInstance class. To get a new SiteInstance that is part of the same
// BrowsingInstance, use SiteInstance::GetRelatedSiteInstance.
//
///////////////////////////////////////////////////////////////////////////////
class BrowsingInstance : public base::RefCounted<BrowsingInstance> {
public:
// Create a new BrowsingInstance.
BrowsingInstance(Profile* profile)
: profile_(profile) {
}
// Virtual to allow tests to extend it.
virtual ~BrowsingInstance() {
// We should only be deleted when all of the SiteInstances that refer to
// us are gone.
DCHECK(site_instance_map_.empty());
}
// Returns whether the process-per-site model is in use (globally or just for
// the given url), in which case we should ensure there is only one
// SiteInstance per site for the entire profile, not just for this
// BrowsingInstance.
virtual bool ShouldUseProcessPerSite(const GURL& url);
// Get the profile to which this BrowsingInstance belongs.
Profile* profile() { return profile_; }
// Returns whether this BrowsingInstance has registered a SiteInstance for
// the site of the given URL.
bool HasSiteInstance(const GURL& url);
// Get the SiteInstance responsible for rendering the given URL. Should
// create a new one if necessary, but should not create more than one
// SiteInstance per site.
SiteInstance* GetSiteInstanceForURL(const GURL& url);
// Adds the given SiteInstance to our map, to ensure that we do not create
// another SiteInstance for the same site.
void RegisterSiteInstance(SiteInstance* site_instance);
// Removes the given SiteInstance from our map, after all references to it
// have been deleted. This means it is safe to create a new SiteInstance
// if the user later visits a page from this site, within this
// BrowsingInstance.
void UnregisterSiteInstance(SiteInstance* site_instance);
private:
// Map of site to SiteInstance, to ensure we only have one SiteInstance per
// site. The site string should be the possibly_invalid_spec() of a GURL
// obtained with SiteInstance::GetSiteForURL.
typedef base::hash_map<std::string, SiteInstance*> SiteInstanceMap;
// Map of Profile to SiteInstanceMap, for use in the process-per-site model.
typedef base::hash_map<Profile*, SiteInstanceMap> ProfileSiteInstanceMap;
// Returns a pointer to the relevant SiteInstanceMap for this object. If the
// process-per-site model is in use, or if process-per-site-instance is in
// use and |url| matches a site for which we always use one process (e.g.,
// the new tab page), then this returns the SiteInstanceMap for the entire
// profile. If not, this returns the BrowsingInstance's own private
// SiteInstanceMap.
SiteInstanceMap* GetSiteInstanceMap(Profile* profile, const GURL& url);
// Common profile to which all SiteInstances in this BrowsingInstance
// must belong.
Profile* const profile_;
// Map of site to SiteInstance, to ensure we only have one SiteInstance per
// site. The site string should be the possibly_invalid_spec() of a GURL
// obtained with SiteInstance::GetSiteForURL. Note that this map may not
// contain every active SiteInstance, because a race exists where two
// SiteInstances can be assigned to the same site. This is ok in rare cases.
// This field is only used if we are not using process-per-site.
SiteInstanceMap site_instance_map_;
// Global map of Profile to SiteInstanceMap, for process-per-site.
static ProfileSiteInstanceMap profile_site_instance_map_;
DISALLOW_EVIL_CONSTRUCTORS(BrowsingInstance);
};
#endif // CHROME_BROWSER_BROWSING_INSTANCE_H__
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