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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
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