wifi_data_provider_common.h revision 868fa2fe829687343ffae624259930155e16dbd8 
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#ifndef CONTENT_BROWSER_GEOLOCATION_WIFI_DATA_PROVIDER_COMMON_H_
6#define CONTENT_BROWSER_GEOLOCATION_WIFI_DATA_PROVIDER_COMMON_H_
7
8#include <assert.h>
9
10#include "base/logging.h"
11#include "base/memory/scoped_ptr.h"
12#include "base/memory/weak_ptr.h"
13#include "base/strings/string16.h"
14#include "base/threading/thread.h"
15#include "content/browser/geolocation/device_data_provider.h"
16#include "content/common/content_export.h"
17
18namespace content {
19
20// Converts a MAC address stored as an array of uint8 to a string.
21string16 MacAddressAsString16(const uint8 mac_as_int[6]);
22
23// Allows sharing and mocking of the update polling policy function.
24class PollingPolicyInterface {
25 public:
26  virtual ~PollingPolicyInterface() {}
27  // Calculates the new polling interval for wiFi scans, given the previous
28  // interval and whether the last scan produced new results.
29  virtual void UpdatePollingInterval(bool scan_results_differ) = 0;
30  virtual int PollingInterval() = 0;
31  virtual int NoWifiInterval() = 0;
32};
33
34// Generic polling policy, constants are compile-time parameterized to allow
35// tuning on a per-platform basis.
36template<int DEFAULT_INTERVAL,
37         int NO_CHANGE_INTERVAL,
38         int TWO_NO_CHANGE_INTERVAL,
39         int NO_WIFI_INTERVAL>
40class GenericPollingPolicy : public PollingPolicyInterface {
41 public:
42  GenericPollingPolicy() : polling_interval_(DEFAULT_INTERVAL) {}
43  // PollingPolicyInterface
44  virtual void UpdatePollingInterval(bool scan_results_differ) {
45    if (scan_results_differ) {
46      polling_interval_ = DEFAULT_INTERVAL;
47    } else if (polling_interval_ == DEFAULT_INTERVAL) {
48      polling_interval_ = NO_CHANGE_INTERVAL;
49    } else {
50      DCHECK(polling_interval_ == NO_CHANGE_INTERVAL ||
51             polling_interval_ == TWO_NO_CHANGE_INTERVAL);
52      polling_interval_ = TWO_NO_CHANGE_INTERVAL;
53    }
54  }
55  virtual int PollingInterval() { return polling_interval_; }
56  virtual int NoWifiInterval() { return NO_WIFI_INTERVAL; }
57
58 private:
59  int polling_interval_;
60};
61
62// Base class to promote code sharing between platform specific wifi data
63// providers. It's optional for specific platforms to derive this, but if they
64// do threading and polling is taken care of by this base class, and all the
65// platform need do is provide the underlying WLAN access API and policy policy,
66// both of which will be create & accessed in the worker thread (only).
67// Also designed this way to promotes ease of testing the cross-platform
68// behavior w.r.t. polling & threading.
69class CONTENT_EXPORT WifiDataProviderCommon
70    : public WifiDataProviderImplBase,
71      private base::Thread {
72 public:
73  // Interface to abstract the low level data OS library call, and to allow
74  // mocking (hence public).
75  class WlanApiInterface {
76   public:
77    virtual ~WlanApiInterface() {}
78    // Gets wifi data for all visible access points.
79    virtual bool GetAccessPointData(WifiData::AccessPointDataSet* data) = 0;
80  };
81
82  WifiDataProviderCommon();
83
84  // WifiDataProviderImplBase implementation
85  virtual bool StartDataProvider() OVERRIDE;
86  virtual void StopDataProvider() OVERRIDE;
87  virtual bool GetData(WifiData* data) OVERRIDE;
88
89 protected:
90  virtual ~WifiDataProviderCommon();
91
92  // Returns ownership. Will be called from the worker thread.
93  virtual WlanApiInterface* NewWlanApi() = 0;
94
95  // Returns ownership. Will be called from the worker thread.
96  virtual PollingPolicyInterface* NewPollingPolicy() = 0;
97
98 private:
99  // Thread implementation
100  virtual void Init() OVERRIDE;
101  virtual void CleanUp() OVERRIDE;
102
103  // Task which run in the child thread.
104  void DoWifiScanTask();
105
106  // Will schedule a scan; i.e. enqueue DoWifiScanTask deferred task.
107  void ScheduleNextScan(int interval);
108
109  WifiData wifi_data_;
110  base::Lock data_mutex_;
111
112  // Whether we've successfully completed a scan for WiFi data (or the polling
113  // thread has terminated early).
114  bool is_first_scan_complete_;
115
116  // Underlying OS wifi API.
117  scoped_ptr<WlanApiInterface> wlan_api_;
118
119  // Controls the polling update interval.
120  scoped_ptr<PollingPolicyInterface> polling_policy_;
121
122  // Holder for the tasks which run on the thread; takes care of cleanup.
123  base::WeakPtrFactory<WifiDataProviderCommon> weak_factory_;
124
125  DISALLOW_COPY_AND_ASSIGN(WifiDataProviderCommon);
126};
127
128}  // namespace content
129
130#endif  // CONTENT_BROWSER_GEOLOCATION_WIFI_DATA_PROVIDER_COMMON_H_
131