content/browser/geolocation/network_location_provider.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/geolocation/network_location_provider.h"
   6
   7 #include "base/bind.h"
   8 #include "base/time.h"
   9 #include "base/utf_string_conversions.h"
  10 #include "content/public/browser/access_token_store.h"
  11
  12 namespace content {
  13 namespace {
  14 // The maximum period of time we'll wait for a complete set of device data
  15 // before sending the request.
  16 const int kDataCompleteWaitSeconds = 2;
  17 }  // namespace
  18
  19 // static
  20 const size_t NetworkLocationProvider::PositionCache::kMaximumSize = 10;
  21
  22 NetworkLocationProvider::PositionCache::PositionCache() {}
  23
  24 NetworkLocationProvider::PositionCache::~PositionCache() {}
  25
  26 bool NetworkLocationProvider::PositionCache::CachePosition(
  27     const WifiData& wifi_data,
  28     const Geoposition& position) {
  29   // Check that we can generate a valid key for the device data.
  30   string16 key;
  31   if (!MakeKey(wifi_data, &key)) {
  32     return false;
  33   }
  34   // If the cache is full, remove the oldest entry.
  35   if (cache_.size() == kMaximumSize) {
  36     DCHECK(cache_age_list_.size() == kMaximumSize);
  37     CacheAgeList::iterator oldest_entry = cache_age_list_.begin();
  38     DCHECK(oldest_entry != cache_age_list_.end());
  39     cache_.erase(*oldest_entry);
  40     cache_age_list_.erase(oldest_entry);
  41   }
  42   DCHECK_LT(cache_.size(), kMaximumSize);
  43   // Insert the position into the cache.
  44   std::pair<CacheMap::iterator, bool> result =
  45       cache_.insert(std::make_pair(key, position));
  46   if (!result.second) {
  47     NOTREACHED();  // We never try to add the same key twice.
  48     CHECK_EQ(cache_.size(), cache_age_list_.size());
  49     return false;
  50   }
  51   cache_age_list_.push_back(result.first);
  52   DCHECK_EQ(cache_.size(), cache_age_list_.size());
  53   return true;
  54 }
  55
  56 // Searches for a cached position response for the current set of cell ID and
  57 // WiFi data. Returns the cached position if available, NULL otherwise.
  58 const Geoposition* NetworkLocationProvider::PositionCache::FindPosition(
  59     const WifiData& wifi_data) {
  60   string16 key;
  61   if (!MakeKey(wifi_data, &key)) {
  62     return NULL;
  63   }
  64   CacheMap::const_iterator iter = cache_.find(key);
  65   return iter == cache_.end() ? NULL : &iter->second;
  66 }
  67
  68 // Makes the key for the map of cached positions, using a set of
  69 // device data. Returns true if a good key was generated, false otherwise.
  70 //
  71 // static
  72 bool NetworkLocationProvider::PositionCache::MakeKey(
  73     const WifiData& wifi_data,
  74     string16* key) {
  75   // Currently we use only the WiFi data, and base the key only on
  76   // the MAC addresses.
  77   DCHECK(key);
  78   key->clear();
  79   const size_t kCharsPerMacAddress = 6 * 3 + 1;  // e.g. "11:22:33:44:55:66|"
  80   key->reserve(wifi_data.access_point_data.size() * kCharsPerMacAddress);
  81   const string16 separator(ASCIIToUTF16("|"));
  82   for (WifiData::AccessPointDataSet::const_iterator iter =
  83        wifi_data.access_point_data.begin();
  84        iter != wifi_data.access_point_data.end();
  85        iter++) {
  86     *key += separator;
  87     *key += iter->mac_address;
  88     *key += separator;
  89   }
  90   // If the key is the empty string, return false, as we don't want to cache a
  91   // position for such a set of device data.
  92   return !key->empty();
  93 }
  94
  95 // NetworkLocationProvider factory function
  96 LocationProviderBase* NewNetworkLocationProvider(
  97     AccessTokenStore* access_token_store,
  98     net::URLRequestContextGetter* context,
  99     const GURL& url,
 100     const string16& access_token) {
 101   return new NetworkLocationProvider(
 102       access_token_store, context, url, access_token);
 103 }
 104
 105 // NetworkLocationProvider
 106 NetworkLocationProvider::NetworkLocationProvider(
 107     AccessTokenStore* access_token_store,
 108     net::URLRequestContextGetter* url_context_getter,
 109     const GURL& url,
 110     const string16& access_token)
 111     : access_token_store_(access_token_store),
 112       wifi_data_provider_(NULL),
 113       is_wifi_data_complete_(false),
 114       access_token_(access_token),
 115       is_permission_granted_(false),
 116       is_new_data_available_(false),
 117       ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)) {
 118   // Create the position cache.
 119   position_cache_.reset(new PositionCache());
 120
 121   request_.reset(new NetworkLocationRequest(url_context_getter, url, this));
 122 }
 123
 124 NetworkLocationProvider::~NetworkLocationProvider() {
 125   StopProvider();
 126 }
 127
 128 // LocationProviderBase implementation
 129 void NetworkLocationProvider::GetPosition(Geoposition *position) {
 130   DCHECK(position);
 131   *position = position_;
 132 }
 133
 134 void NetworkLocationProvider::UpdatePosition() {
 135   // TODO(joth): When called via the public (base class) interface, this should
 136   // poke each data provider to get them to expedite their next scan.
 137   // Whilst in the delayed start, only send request if all data is ready.
 138   if (!weak_factory_.HasWeakPtrs() || is_wifi_data_complete_) {
 139     RequestPosition();
 140   }
 141 }
 142
 143 void NetworkLocationProvider::OnPermissionGranted() {
 144   const bool was_permission_granted = is_permission_granted_;
 145   is_permission_granted_ = true;
 146   if (!was_permission_granted && IsStarted()) {
 147     UpdatePosition();
 148   }
 149 }
 150
 151 // DeviceDataProviderInterface::ListenerInterface implementation.
 152 void NetworkLocationProvider::DeviceDataUpdateAvailable(
 153     WifiDataProvider* provider) {
 154   DCHECK(provider == wifi_data_provider_);
 155   is_wifi_data_complete_ = wifi_data_provider_->GetData(&wifi_data_);
 156   OnDeviceDataUpdated();
 157 }
 158
 159 // NetworkLocationRequest::ListenerInterface implementation.
 160 void NetworkLocationProvider::LocationResponseAvailable(
 161     const Geoposition& position,
 162     bool server_error,
 163     const string16& access_token,
 164     const WifiData& wifi_data) {
 165   DCHECK(CalledOnValidThread());
 166   // Record the position and update our cache.
 167   position_ = position;
 168   if (position.Validate()) {
 169     position_cache_->CachePosition(wifi_data, position);
 170   }
 171
 172   // Record access_token if it's set.
 173   if (!access_token.empty() && access_token_ != access_token) {
 174     access_token_ = access_token;
 175     access_token_store_->SaveAccessToken(request_->url(), access_token);
 176   }
 177
 178   // Let listeners know that we now have a position available.
 179   UpdateListeners();
 180 }
 181
 182 bool NetworkLocationProvider::StartProvider(bool high_accuracy) {
 183   DCHECK(CalledOnValidThread());
 184   if (IsStarted())
 185     return true;
 186   DCHECK(wifi_data_provider_ == NULL);
 187   if (!request_->url().is_valid()) {
 188     LOG(WARNING) << "StartProvider() : Failed, Bad URL: "
 189                  << request_->url().possibly_invalid_spec();
 190     return false;
 191   }
 192
 193   // Get the device data providers. The first call to Register will create the
 194   // provider and it will be deleted by ref counting.
 195   wifi_data_provider_ = WifiDataProvider::Register(this);
 196
 197   MessageLoop::current()->PostDelayedTask(
 198       FROM_HERE,
 199       base::Bind(&NetworkLocationProvider::RequestPosition,
 200                  weak_factory_.GetWeakPtr()),
 201       base::TimeDelta::FromSeconds(kDataCompleteWaitSeconds));
 202   // Get the device data.
 203   is_wifi_data_complete_ = wifi_data_provider_->GetData(&wifi_data_);
 204   if (is_wifi_data_complete_)
 205     OnDeviceDataUpdated();
 206   return true;
 207 }
 208
 209 void NetworkLocationProvider::StopProvider() {
 210   DCHECK(CalledOnValidThread());
 211   if (IsStarted()) {
 212     wifi_data_provider_->Unregister(this);
 213   }
 214   wifi_data_provider_ = NULL;
 215   weak_factory_.InvalidateWeakPtrs();
 216 }
 217
 218 // Other methods
 219 void NetworkLocationProvider::RequestPosition() {
 220   DCHECK(CalledOnValidThread());
 221   if (!is_new_data_available_)
 222     return;
 223
 224   const Geoposition* cached_position =
 225       position_cache_->FindPosition(wifi_data_);
 226   DCHECK(!device_data_updated_timestamp_.is_null()) <<
 227       "Timestamp must be set before looking up position";
 228   if (cached_position) {
 229     DCHECK(cached_position->Validate());
 230     // Record the position and update its timestamp.
 231     position_ = *cached_position;
 232     // The timestamp of a position fix is determined by the timestamp
 233     // of the source data update. (The value of position_.timestamp from
 234     // the cache could be from weeks ago!)
 235     position_.timestamp = device_data_updated_timestamp_;
 236     is_new_data_available_ = false;
 237     // Let listeners know that we now have a position available.
 238     UpdateListeners();
 239     return;
 240   }
 241   // Don't send network requests until authorized. http://crbug.com/39171
 242   if (!is_permission_granted_)
 243     return;
 244
 245   weak_factory_.InvalidateWeakPtrs();
 246   is_new_data_available_ = false;
 247
 248   // TODO(joth): Rather than cancel pending requests, we should create a new
 249   // NetworkLocationRequest for each and hold a set of pending requests.
 250   if (request_->is_request_pending()) {
 251     DVLOG(1) << "NetworkLocationProvider - pre-empting pending network request "
 252                 "with new data. Wifi APs: "
 253              << wifi_data_.access_point_data.size();
 254   }
 255   request_->MakeRequest(access_token_, wifi_data_,
 256                         device_data_updated_timestamp_);
 257 }
 258
 259 void NetworkLocationProvider::OnDeviceDataUpdated() {
 260   DCHECK(CalledOnValidThread());
 261   device_data_updated_timestamp_ = base::Time::Now();
 262
 263   is_new_data_available_ = is_wifi_data_complete_;
 264   UpdatePosition();
 265 }
 266
 267 bool NetworkLocationProvider::IsStarted() const {
 268   return wifi_data_provider_ != NULL;
 269 }
 270
 271 }  // namespace content