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// 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 "device/geolocation/network_location_provider.h"
#include <utility>
#include "base/bind.h"
#include "base/location.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/utf_string_conversions.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/time/time.h"
#include "net/url_request/url_request_context_getter.h"
namespace device {
namespace {
// The maximum period of time we'll wait for a complete set of wifi data
// before sending the request.
const int kDataCompleteWaitSeconds = 2;
} // namespace
// static
const size_t NetworkLocationProvider::PositionCache::kMaximumSize = 10;
NetworkLocationProvider::PositionCache::PositionCache() {}
NetworkLocationProvider::PositionCache::~PositionCache() {}
bool NetworkLocationProvider::PositionCache::CachePosition(
const WifiData& wifi_data,
const Geoposition& position) {
// Check that we can generate a valid key for the wifi data.
base::string16 key;
if (!MakeKey(wifi_data, &key)) {
return false;
}
// If the cache is full, remove the oldest entry.
if (cache_.size() == kMaximumSize) {
DCHECK(cache_age_list_.size() == kMaximumSize);
CacheAgeList::iterator oldest_entry = cache_age_list_.begin();
DCHECK(oldest_entry != cache_age_list_.end());
cache_.erase(*oldest_entry);
cache_age_list_.erase(oldest_entry);
}
DCHECK_LT(cache_.size(), kMaximumSize);
// Insert the position into the cache.
std::pair<CacheMap::iterator, bool> result =
cache_.insert(std::make_pair(key, position));
if (!result.second) {
NOTREACHED(); // We never try to add the same key twice.
CHECK_EQ(cache_.size(), cache_age_list_.size());
return false;
}
cache_age_list_.push_back(result.first);
DCHECK_EQ(cache_.size(), cache_age_list_.size());
return true;
}
// Searches for a cached position response for the current WiFi data. Returns
// the cached position if available, nullptr otherwise.
const Geoposition* NetworkLocationProvider::PositionCache::FindPosition(
const WifiData& wifi_data) {
base::string16 key;
if (!MakeKey(wifi_data, &key)) {
return nullptr;
}
CacheMap::const_iterator iter = cache_.find(key);
return iter == cache_.end() ? nullptr : &iter->second;
}
// Makes the key for the map of cached positions, using the available data.
// Returns true if a good key was generated, false otherwise.
//
// static
bool NetworkLocationProvider::PositionCache::MakeKey(const WifiData& wifi_data,
base::string16* key) {
// Currently we use only WiFi data and base the key only on the MAC addresses.
DCHECK(key);
key->clear();
const size_t kCharsPerMacAddress = 6 * 3 + 1; // e.g. "11:22:33:44:55:66|"
key->reserve(wifi_data.access_point_data.size() * kCharsPerMacAddress);
const base::string16 separator(base::ASCIIToUTF16("|"));
for (const auto& access_point_data : wifi_data.access_point_data) {
*key += separator;
*key += access_point_data.mac_address;
*key += separator;
}
// If the key is the empty string, return false, as we don't want to cache a
// position for such data.
return !key->empty();
}
// NetworkLocationProvider
NetworkLocationProvider::NetworkLocationProvider(
scoped_refptr<net::URLRequestContextGetter> url_context_getter,
const std::string& api_key)
: wifi_data_provider_manager_(nullptr),
wifi_data_update_callback_(
base::Bind(&NetworkLocationProvider::OnWifiDataUpdate,
base::Unretained(this))),
is_wifi_data_complete_(false),
is_permission_granted_(false),
is_new_data_available_(false),
request_(new NetworkLocationRequest(
std::move(url_context_getter),
api_key,
base::Bind(&NetworkLocationProvider::OnLocationResponse,
base::Unretained(this)))),
position_cache_(new PositionCache),
weak_factory_(this) {}
NetworkLocationProvider::~NetworkLocationProvider() {
DCHECK(thread_checker_.CalledOnValidThread());
if (IsStarted())
StopProvider();
}
void NetworkLocationProvider::SetUpdateCallback(
const LocationProvider::LocationProviderUpdateCallback& callback) {
DCHECK(thread_checker_.CalledOnValidThread());
location_provider_update_callback_ = callback;
}
void NetworkLocationProvider::OnPermissionGranted() {
const bool was_permission_granted = is_permission_granted_;
is_permission_granted_ = true;
if (!was_permission_granted && IsStarted())
RequestPosition();
}
void NetworkLocationProvider::OnWifiDataUpdate() {
DCHECK(thread_checker_.CalledOnValidThread());
DCHECK(IsStarted());
is_wifi_data_complete_ = wifi_data_provider_manager_->GetData(&wifi_data_);
if (!is_wifi_data_complete_)
return;
wifi_timestamp_ = base::Time::Now();
is_new_data_available_ = true;
RequestPosition();
}
void NetworkLocationProvider::OnLocationResponse(
const Geoposition& position,
bool server_error,
const WifiData& wifi_data) {
DCHECK(thread_checker_.CalledOnValidThread());
// Record the position and update our cache.
position_ = position;
if (position.Validate())
position_cache_->CachePosition(wifi_data, position);
// Let listeners know that we now have a position available.
if (!location_provider_update_callback_.is_null())
location_provider_update_callback_.Run(this, position_);
}
bool NetworkLocationProvider::StartProvider(bool high_accuracy) {
DCHECK(thread_checker_.CalledOnValidThread());
if (IsStarted())
return true;
// Registers a callback with the data provider. The first call to Register()
// will create a singleton data provider that will be deleted on Unregister().
wifi_data_provider_manager_ =
WifiDataProviderManager::Register(&wifi_data_update_callback_);
base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
FROM_HERE, base::Bind(&NetworkLocationProvider::RequestPosition,
weak_factory_.GetWeakPtr()),
base::TimeDelta::FromSeconds(kDataCompleteWaitSeconds));
OnWifiDataUpdate();
return true;
}
void NetworkLocationProvider::StopProvider() {
DCHECK(thread_checker_.CalledOnValidThread());
DCHECK(IsStarted());
wifi_data_provider_manager_->Unregister(&wifi_data_update_callback_);
wifi_data_provider_manager_ = nullptr;
weak_factory_.InvalidateWeakPtrs();
}
const Geoposition& NetworkLocationProvider::GetPosition() {
return position_;
}
void NetworkLocationProvider::RequestPosition() {
DCHECK(thread_checker_.CalledOnValidThread());
if (!is_new_data_available_ || !is_wifi_data_complete_)
return;
DCHECK(!wifi_timestamp_.is_null())
<< "|wifi_timestamp_| must be set before looking up position";
const Geoposition* cached_position =
position_cache_->FindPosition(wifi_data_);
if (cached_position) {
DCHECK(cached_position->Validate());
// Record the position and update its timestamp.
position_ = *cached_position;
// The timestamp of a position fix is determined by the timestamp
// of the source data update. (The value of position_.timestamp from
// the cache could be from weeks ago!)
position_.timestamp = wifi_timestamp_;
is_new_data_available_ = false;
// Let listeners know that we now have a position available.
if (!location_provider_update_callback_.is_null())
location_provider_update_callback_.Run(this, position_);
return;
}
// Don't send network requests until authorized. http://crbug.com/39171
if (!is_permission_granted_)
return;
is_new_data_available_ = false;
// TODO(joth): Rather than cancel pending requests, we should create a new
// NetworkLocationRequest for each and hold a set of pending requests.
DLOG_IF(WARNING, request_->is_request_pending())
<< "NetworkLocationProvider - pre-empting pending network request "
"with new data. Wifi APs: "
<< wifi_data_.access_point_data.size();
request_->MakeRequest(wifi_data_, wifi_timestamp_);
}
bool NetworkLocationProvider::IsStarted() const {
return wifi_data_provider_manager_ != nullptr;
}
} // namespace device
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