Add chrome to the repository.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@15 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 131 insertions, 0 deletions

diff --git a/chrome/browser/history/visit_tracker.cc b/chrome/browser/history/visit_tracker.cc
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+// Copyright 2008, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "chrome/browser/history/visit_tracker.h"
+
+#include "base/logging.h"
+
+namespace history {
+
+// When the list gets longer than 'MaxItems', CleanupTransitionList will resize
+// the list down to 'ResizeTo' size. This is so we only do few block moves of
+// the data rather than constantly shuffle stuff around in the vector.
+static const int kMaxItemsInTransitionList = 96;
+static const int kResizeBigTransitionListTo = 64;
+COMPILE_ASSERT(kResizeBigTransitionListTo < kMaxItemsInTransitionList,
+               max_items_must_be_larger_than_resize_to);
+
+VisitTracker::VisitTracker() {
+}
+
+VisitTracker::~VisitTracker() {
+  STLDeleteContainerPairSecondPointers(hosts_.begin(), hosts_.end());
+}
+
+// This function is potentially slow because it may do up to two brute-force
+// searches of the transitions list. This transitions list is kept to a
+// relatively small number by CleanupTransitionList so it shouldn't be a big
+// deal. However, if this ends up being noticable for performance, we may want
+// to optimize lookup.
+VisitID VisitTracker::GetLastVisit(const void* host,
+                                   int32 page_id,
+                                   const GURL& referrer) {
+  if (referrer.is_empty() || !host)
+    return 0;
+
+  HostList::iterator i = hosts_.find(host);
+  if (i == hosts_.end())
+    return 0;  // We don't have any entries for this host.
+  TransitionList& transitions = *i->second;
+
+  // Recall that a page ID is associated with a single session history entry.
+  // In the case of automatically loaded iframes, many visits/URLs can have the
+  // same page ID.
+  //
+  // We search backwards, starting at the current page ID, for the referring
+  // URL. This won't always be correct. For example, if a render process has
+  // the same page open in two different tabs, or even in two different frames,
+  // we can get confused about which was which. We can have the renderer
+  // report more precise referrer information in the future, but this is a
+  // hard problem and doesn't affect much in terms of real-world issues.
+  //
+  // We assume that the page IDs are increasing over time, so larger IDs than
+  // the current input ID happened in the future (this will occur if the user
+  // goes back). We can ignore future transitions because if you navigate, go
+  // back, and navigate some more, we'd like to have one node with two out
+  // edges in our visit graph.
+  for (int i = static_cast<int>(transitions.size()) - 1; i >= 0; i--) {
+    if (transitions[i].page_id <= page_id && transitions[i].url == referrer) {
+      // Found it.
+      return transitions[i].visit_id;
+    }
+  }
+
+  // We can't find the referrer.
+  return 0;
+}
+
+void VisitTracker::AddVisit(const void* host,
+                            int32 page_id,
+                            const GURL& url,
+                            VisitID visit_id) {
+  TransitionList* transitions = hosts_[host];
+  if (!transitions) {
+    transitions = new TransitionList;
+    hosts_[host] = transitions;
+  }
+
+  Transition t;
+  t.url = url;
+  t.page_id = page_id;
+  t.visit_id = visit_id;
+  transitions->push_back(t);
+
+  CleanupTransitionList(transitions);
+}
+
+void VisitTracker::NotifyRenderProcessHostDestruction(const void* host) {
+  HostList::iterator i = hosts_.find(host);
+  if (i == hosts_.end())
+    return;  // We don't have any entries for this host.
+
+  delete i->second;
+  hosts_.erase(i);
+}
+
+
+void VisitTracker::CleanupTransitionList(TransitionList* transitions) {
+  if (transitions->size() <= kMaxItemsInTransitionList)
+    return;  // Nothing to do.
+
+  transitions->erase(transitions->begin(),
+                     transitions->begin() + kResizeBigTransitionListTo);
+}
+
+}  // namespace history