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/common/referrer.h"
+#include "googleurl/src/gurl.h"
+#include "googleurl/src/url_canon.h"
+#include "ui/gfx/size.h"
+
+namespace {
+
+template<typename MapForwards, typename MapBackwards>
+bool MapsAreInverseOfEachOther(const MapForwards& map_forwards,
+                               const MapBackwards& map_backwards) {
+  if (map_forwards.size() != map_backwards.size())
+    return false;
+  for (typename MapForwards::const_iterator i = map_forwards.begin();
+       i != map_forwards.end(); ++i) {
+    // Best to use std::count here both times, as
+    // AssociativeContainer::count returns size_t, vs. std::count
+    // returning iterator_traits<InputIterator>::difference_type
+    typedef typename std::iterator_traits<
+        typename MapForwards::iterator>::difference_type diff_type;
+    diff_type forwards_count =
+        std::count(map_forwards.begin(), map_forwards.end(),
+                   typename MapForwards::value_type(i->first, i->second));
+    diff_type backwards_count =
+        std::count(map_backwards.begin(), map_backwards.end(),
+                   typename MapBackwards::value_type(i->second, i->first));
+    if (forwards_count != backwards_count)
+      return false;
+  }
+  return true;
+}
+
+}  // end namespace
+
+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& ALLOW_UNUSED 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();
+  DCHECK(MapsAreInverseOfEachOther(ids_to_url_map_, urls_to_id_map_));
+  // TODO(gavinp): Add tests to insure fragments work, then remove this fragment
+  // clearing code.
+  url_canon::Replacements<char> replacements;
+  replacements.ClearRef();
+  const GURL url = orig_url.ReplaceComponents(replacements);
+
+  // TODO(gavinp,dominich): After the Prerender API can send events back to
+  // their client links, revisit having both maps and all the trouble that
+  // causes.
+  if (!manager_->AddPrerenderFromLinkRelPrerender(
+          child_id, render_view_route_id, url, referrer))
+    return false;
+  const ChildAndPrerenderIdPair child_and_prerender_id(child_id, prerender_id);
+  DCHECK(ids_to_url_map_.find(child_and_prerender_id) == ids_to_url_map_.end());
+  ids_to_url_map_.insert(std::make_pair(child_and_prerender_id, url));
+  urls_to_id_map_.insert(std::make_pair(url, child_and_prerender_id));
+  DCHECK(MapsAreInverseOfEachOther(ids_to_url_map_, urls_to_id_map_));
+  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;
+  RemovePrerender(id_url_iter);
+
+  if (urls_to_id_map_.find(url) != urls_to_id_map_.end())
+    return;
+
+  // TODO(gavinp): Track down the correct prerender and stop it, rather than
+  // this nuclear option, which assumes that only one prerender at a time
+  // runs.
+  if (PrerenderContents* contents = manager_->GetEntry(url))
+    contents->Destroy(FINAL_STATUS_CANCELLED);
+}
+
+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);
+  IdPairToUrlMap::iterator id_url_iter =
+      ids_to_url_map_.find(child_and_prerender_id);
+  if (id_url_iter == ids_to_url_map_.end()) {
+    // FIXME(gavinp): Currently, canceled prerenders also get abandoned later.
+    // When the WebKit fix to stop this lands, add a NOTREACHED() here.
+    return;
+  }
+  RemovePrerender(id_url_iter);
+}
+
+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();
+  }
+}
+
+void PrerenderLinkManager::RemovePrerender(
+    const IdPairToUrlMap::iterator& id_url_iter) {
+  DCHECK(MapsAreInverseOfEachOther(ids_to_url_map_, urls_to_id_map_));
+  const GURL url = id_url_iter->second;
+  const ChildAndPrerenderIdPair child_and_prerender_id = id_url_iter->first;
+  ids_to_url_map_.erase(id_url_iter);
+
+  for (UrlToIdPairMap::iterator i = urls_to_id_map_.lower_bound(url),
+                                e = urls_to_id_map_.upper_bound(url);
+       i != e; ++i) {
+    if (i->second == child_and_prerender_id) {
+      urls_to_id_map_.erase(i);
+      DCHECK(MapsAreInverseOfEachOther(ids_to_url_map_, urls_to_id_map_));
+      return;
+    }
+  }
+  NOTREACHED();
+}
+
+bool PrerenderLinkManager::IsEmpty() const {
+  return ids_to_url_map_.empty();
+}
+
+}  // namespace prerender
+