content/browser/geolocation/wifi_data_provider_common.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/wifi_data_provider_common.h"
   6
   7 #include "base/bind.h"
   8 #include "base/stringprintf.h"
   9 #include "base/utf_string_conversions.h"
  10
  11 namespace content {
  12
  13 string16 MacAddressAsString16(const uint8 mac_as_int[6]) {
  14   // mac_as_int is big-endian. Write in byte chunks.
  15   // Format is XX-XX-XX-XX-XX-XX.
  16   static const char* const kMacFormatString =
  17       "%02x-%02x-%02x-%02x-%02x-%02x";
  18   return ASCIIToUTF16(base::StringPrintf(kMacFormatString,
  19                                         mac_as_int[0],
  20                                         mac_as_int[1],
  21                                         mac_as_int[2],
  22                                         mac_as_int[3],
  23                                         mac_as_int[4],
  24                                         mac_as_int[5]));
  25 }
  26
  27 WifiDataProviderCommon::WifiDataProviderCommon()
  28     : Thread("Geolocation_wifi_provider"),
  29       is_first_scan_complete_(false),
  30       ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)) {
  31 }
  32
  33 WifiDataProviderCommon::~WifiDataProviderCommon() {
  34   // Thread must be stopped before entering destructor chain to avoid race
  35   // conditions; see comment in DeviceDataProvider::Unregister.
  36   DCHECK(!IsRunning());  // Must call StopDataProvider before destroying me.
  37 }
  38
  39 bool WifiDataProviderCommon::StartDataProvider() {
  40   DCHECK(CalledOnClientThread());
  41   DCHECK(!IsRunning());  // StartDataProvider must only be called once.
  42   return Start();
  43 }
  44
  45 void WifiDataProviderCommon::StopDataProvider() {
  46   DCHECK(CalledOnClientThread());
  47   Stop();
  48 }
  49
  50 bool WifiDataProviderCommon::GetData(WifiData* data) {
  51   DCHECK(CalledOnClientThread());
  52   DCHECK(data);
  53   base::AutoLock lock(data_mutex_);
  54   *data = wifi_data_;
  55   // If we've successfully completed a scan, indicate that we have all of the
  56   // data we can get.
  57   return is_first_scan_complete_;
  58 }
  59
  60 // Thread implementation
  61 void WifiDataProviderCommon::Init() {
  62   DCHECK(wlan_api_ == NULL);
  63   wlan_api_.reset(NewWlanApi());
  64   if (wlan_api_ == NULL) {
  65     // Error! Can't do scans, so don't try and schedule one.
  66     is_first_scan_complete_ = true;
  67     return;
  68   }
  69
  70   DCHECK(polling_policy_ == NULL);
  71   polling_policy_.reset(NewPollingPolicy());
  72   DCHECK(polling_policy_ != NULL);
  73
  74   // Perform first scan ASAP regardless of the polling policy. If this scan
  75   // fails we'll retry at a rate in line with the polling policy.
  76   ScheduleNextScan(0);
  77 }
  78
  79 void WifiDataProviderCommon::CleanUp() {
  80   // Destroy these instances in the thread on which they were created.
  81   wlan_api_.reset();
  82   polling_policy_.reset();
  83 }
  84
  85 void WifiDataProviderCommon::DoWifiScanTask() {
  86   bool update_available = false;
  87   WifiData new_data;
  88   if (!wlan_api_->GetAccessPointData(&new_data.access_point_data)) {
  89     ScheduleNextScan(polling_policy_->NoWifiInterval());
  90   } else {
  91     {
  92       base::AutoLock lock(data_mutex_);
  93       update_available = wifi_data_.DiffersSignificantly(new_data);
  94       wifi_data_ = new_data;
  95     }
  96     polling_policy_->UpdatePollingInterval(update_available);
  97     ScheduleNextScan(polling_policy_->PollingInterval());
  98   }
  99   if (update_available || !is_first_scan_complete_) {
 100     is_first_scan_complete_ = true;
 101     NotifyListeners();
 102   }
 103 }
 104
 105 void WifiDataProviderCommon::ScheduleNextScan(int interval) {
 106   message_loop()->PostDelayedTask(
 107       FROM_HERE,
 108       base::Bind(&WifiDataProviderCommon::DoWifiScanTask,
 109                  weak_factory_.GetWeakPtr()),
 110       base::TimeDelta::FromMilliseconds(interval));
 111 }
 112
 113 }  // namespace content