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/strings/utf_string_conversions.h"
   9 #include "base/time/time.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 wifi 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 wifi data.
  30   base::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 WiFi data. Returns
  57 // the cached position if available, NULL otherwise.
  58 const Geoposition* NetworkLocationProvider::PositionCache::FindPosition(
  59     const WifiData& wifi_data) {
  60   base::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 the available data.
  69 // Returns true if a good key was generated, false otherwise.
  70 //
  71 // static
  72 bool NetworkLocationProvider::PositionCache::MakeKey(
  73     const WifiData& wifi_data,
  74     base::string16* key) {
  75   // Currently we use only WiFi data and base the key only on the MAC addresses.
  76   DCHECK(key);
  77   key->clear();
  78   const size_t kCharsPerMacAddress = 6 * 3 + 1;  // e.g. "11:22:33:44:55:66|"
  79   key->reserve(wifi_data.access_point_data.size() * kCharsPerMacAddress);
  80   const base::string16 separator(base::ASCIIToUTF16("|"));
  81   for (WifiData::AccessPointDataSet::const_iterator iter =
  82        wifi_data.access_point_data.begin();
  83        iter != wifi_data.access_point_data.end();
  84        iter++) {
  85     *key += separator;
  86     *key += iter->mac_address;
  87     *key += separator;
  88   }
  89   // If the key is the empty string, return false, as we don't want to cache a
  90   // position for such data.
  91   return !key->empty();
  92 }
  93
  94 // NetworkLocationProvider factory function
  95 LocationProviderBase* NewNetworkLocationProvider(
  96     AccessTokenStore* access_token_store,
  97     net::URLRequestContextGetter* context,
  98     const GURL& url,
  99     const base::string16& access_token) {
 100   return new NetworkLocationProvider(
 101       access_token_store, context, url, access_token);
 102 }
 103
 104 // NetworkLocationProvider
 105 NetworkLocationProvider::NetworkLocationProvider(
 106     AccessTokenStore* access_token_store,
 107     net::URLRequestContextGetter* url_context_getter,
 108     const GURL& url,
 109     const base::string16& access_token)
 110     : access_token_store_(access_token_store),
 111       wifi_data_provider_(NULL),
 112       wifi_data_update_callback_(
 113           base::Bind(&NetworkLocationProvider::OnWifiDataUpdate,
 114                      base::Unretained(this))),
 115       is_wifi_data_complete_(false),
 116       access_token_(access_token),
 117       is_permission_granted_(false),
 118       is_new_data_available_(false),
 119       weak_factory_(this) {
 120   // Create the position cache.
 121   position_cache_.reset(new PositionCache());
 122
 123   request_.reset(new NetworkLocationRequest(
 124       url_context_getter,
 125       url,
 126       base::Bind(&NetworkLocationProvider::OnLocationResponse,
 127                  base::Unretained(this))));
 128 }
 129
 130 NetworkLocationProvider::~NetworkLocationProvider() {
 131   StopProvider();
 132 }
 133
 134 // LocationProvider implementation
 135 void NetworkLocationProvider::GetPosition(Geoposition* position) {
 136   DCHECK(position);
 137   *position = position_;
 138 }
 139
 140 void NetworkLocationProvider::RequestRefresh() {
 141   // TODO(joth): When called via the public (base class) interface, this should
 142   // poke each data provider to get them to expedite their next scan.
 143   // Whilst in the delayed start, only send request if all data is ready.
 144   if (!weak_factory_.HasWeakPtrs() || is_wifi_data_complete_) {
 145     RequestPosition();
 146   }
 147 }
 148
 149 void NetworkLocationProvider::OnPermissionGranted() {
 150   const bool was_permission_granted = is_permission_granted_;
 151   is_permission_granted_ = true;
 152   if (!was_permission_granted && IsStarted()) {
 153     RequestRefresh();
 154   }
 155 }
 156
 157 void NetworkLocationProvider::OnWifiDataUpdate(WifiDataProvider* provider) {
 158   DCHECK(provider == wifi_data_provider_);
 159   is_wifi_data_complete_ = wifi_data_provider_->GetData(&wifi_data_);
 160   OnWifiDataUpdated();
 161 }
 162
 163 void NetworkLocationProvider::OnLocationResponse(
 164     const Geoposition& position,
 165     bool server_error,
 166     const base::string16& access_token,
 167     const WifiData& wifi_data) {
 168   DCHECK(CalledOnValidThread());
 169   // Record the position and update our cache.
 170   position_ = position;
 171   if (position.Validate()) {
 172     position_cache_->CachePosition(wifi_data, position);
 173   }
 174
 175   // Record access_token if it's set.
 176   if (!access_token.empty() && access_token_ != access_token) {
 177     access_token_ = access_token;
 178     access_token_store_->SaveAccessToken(request_->url(), access_token);
 179   }
 180
 181   // Let listeners know that we now have a position available.
 182   NotifyCallback(position_);
 183 }
 184
 185 bool NetworkLocationProvider::StartProvider(bool high_accuracy) {
 186   DCHECK(CalledOnValidThread());
 187   if (IsStarted())
 188     return true;
 189   DCHECK(wifi_data_provider_ == NULL);
 190   if (!request_->url().is_valid()) {
 191     LOG(WARNING) << "StartProvider() : Failed, Bad URL: "
 192                  << request_->url().possibly_invalid_spec();
 193     return false;
 194   }
 195
 196   // Registers a callback with the data provider. The first call to Register
 197   // will create a singleton data provider and it will be deleted when the last
 198   // callback is removed with Unregister.
 199   wifi_data_provider_ = WifiDataProvider::Register(&wifi_data_update_callback_);
 200
 201   base::MessageLoop::current()->PostDelayedTask(
 202       FROM_HERE,
 203       base::Bind(&NetworkLocationProvider::RequestPosition,
 204                  weak_factory_.GetWeakPtr()),
 205       base::TimeDelta::FromSeconds(kDataCompleteWaitSeconds));
 206   // Get the wifi data.
 207   is_wifi_data_complete_ = wifi_data_provider_->GetData(&wifi_data_);
 208   if (is_wifi_data_complete_)
 209     OnWifiDataUpdated();
 210   return true;
 211 }
 212
 213 void NetworkLocationProvider::OnWifiDataUpdated() {
 214   DCHECK(CalledOnValidThread());
 215   wifi_data_updated_timestamp_ = base::Time::Now();
 216
 217   is_new_data_available_ = is_wifi_data_complete_;
 218   RequestRefresh();
 219 }
 220
 221 void NetworkLocationProvider::StopProvider() {
 222   DCHECK(CalledOnValidThread());
 223   if (IsStarted()) {
 224     wifi_data_provider_->Unregister(&wifi_data_update_callback_);
 225   }
 226   wifi_data_provider_ = NULL;
 227   weak_factory_.InvalidateWeakPtrs();
 228 }
 229
 230 // Other methods
 231 void NetworkLocationProvider::RequestPosition() {
 232   DCHECK(CalledOnValidThread());
 233   if (!is_new_data_available_)
 234     return;
 235
 236   const Geoposition* cached_position =
 237       position_cache_->FindPosition(wifi_data_);
 238   DCHECK(!wifi_data_updated_timestamp_.is_null()) <<
 239       "Timestamp must be set before looking up position";
 240   if (cached_position) {
 241     DCHECK(cached_position->Validate());
 242     // Record the position and update its timestamp.
 243     position_ = *cached_position;
 244     // The timestamp of a position fix is determined by the timestamp
 245     // of the source data update. (The value of position_.timestamp from
 246     // the cache could be from weeks ago!)
 247     position_.timestamp = wifi_data_updated_timestamp_;
 248     is_new_data_available_ = false;
 249     // Let listeners know that we now have a position available.
 250     NotifyCallback(position_);
 251     return;
 252   }
 253   // Don't send network requests until authorized. http://crbug.com/39171
 254   if (!is_permission_granted_)
 255     return;
 256
 257   weak_factory_.InvalidateWeakPtrs();
 258   is_new_data_available_ = false;
 259
 260   // TODO(joth): Rather than cancel pending requests, we should create a new
 261   // NetworkLocationRequest for each and hold a set of pending requests.
 262   if (request_->is_request_pending()) {
 263     DVLOG(1) << "NetworkLocationProvider - pre-empting pending network request "
 264                 "with new data. Wifi APs: "
 265              << wifi_data_.access_point_data.size();
 266   }
 267   request_->MakeRequest(access_token_, wifi_data_,
 268                         wifi_data_updated_timestamp_);
 269 }
 270
 271 bool NetworkLocationProvider::IsStarted() const {
 272   return wifi_data_provider_ != NULL;
 273 }
 274
 275 }  // namespace content