blob: a5929f641c63d7dbb72459f18fa8da3f28fd790c [file] [log] [blame]
// Copyright 2018 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.
#include <list>
#include <memory>
#include "base/macros.h"
#include "content/common/content_export.h"
namespace content {
class RenderFrameHostImpl;
// BackForwardCache:
// After the user navigates away from a document, the old one goes into the
// frozen state and is kept in this object. They can potentially be reused
// after an history navigation. Reusing a document means swapping it back with
// the current_frame_host.
class CONTENT_EXPORT BackForwardCache {
// Returns true when a RenderFrameHost can be stored into the
// BackForwardCache. Depends on the |render_frame_host| and its children's
// state.
bool CanStoreDocument(RenderFrameHostImpl* render_frame_host);
// Moves |render_frame_host| into the BackForwardCache. It can be reused in
// a future history navigation by using RestoreDocument(). When the
// BackForwardCache is full, the least recently used document is evicted.
// Precondition: CanStoreDocument(render_frame_host).
void StoreDocument(std::unique_ptr<RenderFrameHostImpl>);
// Iterates all the RenderViewHost inside |main_rfh| and freeze or unfreeze
// them.
static void Freeze(RenderFrameHostImpl* main_rfh);
static void UnFreeze(RenderFrameHostImpl* main_rfh);
// During a history navigation, move a document out of the BackForwardCache
// knowing its navigation entry ID. Returns nullptr when none is found.
std::unique_ptr<RenderFrameHostImpl> RestoreDocument(int navigation_entry_id);
// Remove all entries from the BackForwardCache.
void Flush();
// Contains the set of stored RenderFrameHost.
// Invariant:
// - Ordered from the most recently used to the last recently used.
// - Once the list is full, the least recently used document is evicted.
std::list<std::unique_ptr<RenderFrameHostImpl>> render_frame_hosts_;
} // namespace content