New link rel=prerender api, using WebKit::WebPrerenderingPlatform

chrome/browser/prerender/prerender_link_manager.cc

+// 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.
+
+#include "chrome/browser/prerender/prerender_link_manager.h"
+
+#include <limits>
+#include <queue>
+#include <utility>
+
+#include "chrome/browser/prerender/prerender_contents.h"
+#include "chrome/browser/prerender/prerender_manager.h"
+#include "chrome/browser/prerender/prerender_manager_factory.h"
+#include "chrome/browser/profiles/profile.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/session_storage_namespace.h"
+#include "content/public/common/referrer.h"
+#include "googleurl/src/gurl.h"
+#include "googleurl/src/url_canon.h"
+#include "ui/gfx/size.h"
+
+using content::RenderViewHost;
+using content::SessionStorageNamespace;
+
+namespace prerender {
+
+PrerenderLinkManager::PrerenderLinkManager(PrerenderManager* manager)
+    : manager_(manager) {
+}
+
+PrerenderLinkManager::~PrerenderLinkManager() {
+}
+
+bool PrerenderLinkManager::OnAddPrerender(int child_id,
+                                          int prerender_id,
+                                          const GURL& orig_url,
+                                          const content::Referrer& referrer,
+                                          const gfx::Size& size,
+                                          int render_view_route_id) {
+  DVLOG(2) << "OnAddPrerender, child_id = " << child_id
+           << ", prerender_id = " << prerender_id
+           << ", url = " << orig_url.spec();
+  DVLOG(3) << "... render_view_route_id = " << render_view_route_id
+           << ", referrer url = " << referrer.url.spec();
+  // TODO(gavinp): Add tests to insure fragments work, then remove this fragment

[dominich, 2012/04/29 18:52:55]

nit: ensure

[gavinp, 2012/04/30 11:43:16]

Done.

+  // clearing code.
+  url_canon::Replacements<char> replacements;
+  replacements.ClearRef();
+  const GURL url = orig_url.ReplaceComponents(replacements);
+
+  // Unit tests pass in a child_id == -1.
+  RenderViewHost* source_render_view_host = NULL;
+  SessionStorageNamespace* session_storage_namespace = NULL;
+  if (child_id != -1) {
+    source_render_view_host =
+        RenderViewHost::FromID(child_id, render_view_route_id);
+    if (!source_render_view_host || !source_render_view_host->GetView())
+      return false;
+    session_storage_namespace =
+        source_render_view_host->GetSessionStorageNamespace();
+  }
+
+  if (!manager_->AddPrerenderFromLinkRelPrerender(

[dominich, 2012/04/29 18:52:55]

possibly contentious comment: why not move this map to the PrerenderManager and
use that as a key for all active Prerenders instead of using the
URL/SessionStorage as a key?

Yes, this would make this merely a wrapper interface, but I think that's
reasonable.

[gavinp, 2012/04/30 11:43:16]

We don't key on url/sessionstorage though.  The key is the prerender_id,
assigned in chrome/renderer/prerender/prerenderer_client.cc.  The fact that
adding the same url twice sometimes causes a request to map to the same
underlying prerender is now a detail that only the prerender_manager is
concerned with...

I think a good question is: should AddPrerender... et al return a handle to the
prerender they created, so I can later refer to it without searching based on
the key criteria the prerender manager exposes?  That would make cancel not
require an url, either, which is awesome; our maps would be from a
child_and_link_prerender_id to a prerender_id (from the prerender manager).

[dominich, 2012/04/30 15:52:05]

I believe this will be necessary (or convenient) for multiple prerender support.
I can't decide if it should be part of this CL as it complicates the work on
PrerenderManager, but it introduces significant changes to this class.

I suggest leaving this CL as it is, but creating a bug to make the change to a
PrerenderHandle. It will simplify this case, and also allow easier cancelation
from Omnibox, and will be useful for handling edge cases in multiple prerender
support. Does anyone disagree?

+          child_id, render_view_route_id, url, referrer,
+          size, session_storage_namespace))
+    return false;
+  const ChildAndPrerenderIdPair child_and_prerender_id(child_id, prerender_id);
+  DCHECK(!ids_to_url_map_.count(child_and_prerender_id));
+  ids_to_url_map_.insert(std::make_pair(child_and_prerender_id, url));
+  return true;
+}
+
+void PrerenderLinkManager::OnCancelPrerender(int prerender_id,
+                                             int child_id) {
+  DVLOG(2) << "OnCancelPrerender, child_id = " << child_id
+           << ", prerender_id = " << prerender_id;
+  const ChildAndPrerenderIdPair child_and_prerender_id(child_id, prerender_id);
+  IdPairToUrlMap::iterator id_url_iter =
+      ids_to_url_map_.find(child_and_prerender_id);
+  if (id_url_iter == ids_to_url_map_.end()) {
+    DVLOG(5) << "... canceling a prerender that doesn't exist.";
+    return;
+  }
+  const GURL url = id_url_iter->second;
+  ids_to_url_map_.erase(id_url_iter);
+  manager_->MaybeCancelPrerender(url);
+}
+
+void PrerenderLinkManager::OnAbandonPrerender(int prerender_id, int child_id) {
+  DVLOG(2) << "OnAbandonPrerender, child_id = " << child_id
+           << ", prerender_id = " << prerender_id;
+  // TODO(gavinp,cbentzel): Implement reasonable behaviour for
+  // navigation away from launcher.
+  const ChildAndPrerenderIdPair child_and_prerender_id(child_id, prerender_id);
+  if (ids_to_url_map_.count(child_and_prerender_id))
+    ids_to_url_map_.erase(child_and_prerender_id);
+}
+
+void PrerenderLinkManager::OnChannelClosing(int child_id) {
+  DVLOG(2) << "OnChannelClosing, child id = " << child_id;
+  const ChildAndPrerenderIdPair child_and_minimum_prerender_id(
+      child_id, std::numeric_limits<int>::min());
+  const ChildAndPrerenderIdPair child_and_maximum_prerender_id(
+      child_id, std::numeric_limits<int>::max());
+  std::queue<int> prerender_ids_to_abandon;
+  for (IdPairToUrlMap::iterator
+           i = ids_to_url_map_.lower_bound(child_and_minimum_prerender_id),
+           e = ids_to_url_map_.upper_bound(child_and_maximum_prerender_id);
+       i != e; ++i) {
+    prerender_ids_to_abandon.push(i->first.second);
+  }
+  while (!prerender_ids_to_abandon.empty()) {
+    DVLOG(4) << "---> abandon prerender_id = "
+             << prerender_ids_to_abandon.front();
+    OnAbandonPrerender(prerender_ids_to_abandon.front(), child_id);
+    prerender_ids_to_abandon.pop();
+  }
+}
+
+bool PrerenderLinkManager::IsEmpty() const {
+  return ids_to_url_map_.empty();
+}
+
+}  // namespace prerender
+