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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_NETWORK_LOCATION_PROVIDER_H_
6  #define CONTENT_BROWSER_GEOLOCATION_NETWORK_LOCATION_PROVIDER_H_
7  
8  #include <list>
9  #include <map>
10  
11  #include "base/basictypes.h"
12  #include "base/memory/ref_counted.h"
13  #include "base/memory/scoped_ptr.h"
14  #include "base/memory/weak_ptr.h"
15  #include "base/strings/string16.h"
16  #include "base/threading/non_thread_safe.h"
17  #include "base/threading/thread.h"
18  #include "content/browser/geolocation/location_provider_base.h"
19  #include "content/browser/geolocation/network_location_request.h"
20  #include "content/browser/geolocation/wifi_data_provider_manager.h"
21  #include "content/common/content_export.h"
22  #include "content/public/common/geoposition.h"
23  
24  namespace content {
25  class AccessTokenStore;
26  
27  
28  class NetworkLocationProvider
29      : public base::NonThreadSafe,
30        public LocationProviderBase {
31   public:
32    // Cache of recently resolved locations. Public for tests.
33    class CONTENT_EXPORT PositionCache {
34     public:
35      // The maximum size of the cache of positions.
36      static const size_t kMaximumSize;
37  
38      PositionCache();
39      ~PositionCache();
40  
41      // Caches the current position response for the current set of cell ID and
42      // WiFi data. In the case of the cache exceeding kMaximumSize this will
43      // evict old entries in FIFO orderer of being added.
44      // Returns true on success, false otherwise.
45      bool CachePosition(const WifiData& wifi_data,
46                         const Geoposition& position);
47  
48      // Searches for a cached position response for the current set of data.
49      // Returns NULL if the position is not in the cache, or the cached
50      // position if available. Ownership remains with the cache.
51      const Geoposition* FindPosition(const WifiData& wifi_data);
52  
53     private:
54      // Makes the key for the map of cached positions, using a set of
55      // data. Returns true if a good key was generated, false otherwise.
56      static bool MakeKey(const WifiData& wifi_data,
57                          base::string16* key);
58  
59      // The cache of positions. This is stored as a map keyed on a string that
60      // represents a set of data, and a list to provide
61      // least-recently-added eviction.
62      typedef std::map<base::string16, Geoposition> CacheMap;
63      CacheMap cache_;
64      typedef std::list<CacheMap::iterator> CacheAgeList;
65      CacheAgeList cache_age_list_;  // Oldest first.
66    };
67  
68    NetworkLocationProvider(AccessTokenStore* access_token_store,
69                            net::URLRequestContextGetter* context,
70                            const GURL& url,
71                            const base::string16& access_token);
72    virtual ~NetworkLocationProvider();
73  
74    // LocationProvider implementation
75    virtual bool StartProvider(bool high_accuracy) OVERRIDE;
76    virtual void StopProvider() OVERRIDE;
77    virtual void GetPosition(Geoposition *position) OVERRIDE;
78    virtual void RequestRefresh() OVERRIDE;
79    virtual void OnPermissionGranted() OVERRIDE;
80  
81   private:
82    // Satisfies a position request from cache or network.
83    void RequestPosition();
84  
85    // Gets called when new wifi data is available.
86    void OnWifiDataUpdate();
87  
88    // Internal helper used by OnWifiDataUpdate.
89    void OnWifiDataUpdated();
90  
91    bool IsStarted() const;
92  
93    void OnLocationResponse(const Geoposition& position,
94                            bool server_error,
95                            const base::string16& access_token,
96                            const WifiData& wifi_data);
97  
98    scoped_refptr<AccessTokenStore> access_token_store_;
99  
100    // The wifi data provider, acquired via global factories.
101    WifiDataProviderManager* wifi_data_provider_manager_;
102  
103    WifiDataProviderManager::WifiDataUpdateCallback wifi_data_update_callback_;
104  
105    // The  wifi data and a flag to indicate if the data set is complete.
106    WifiData wifi_data_;
107    bool is_wifi_data_complete_;
108  
109    // The timestamp for the latest wifi data update.
110    base::Time wifi_data_updated_timestamp_;
111  
112    // Cached value loaded from the token store or set by a previous server
113    // response, and sent in each subsequent network request.
114    base::string16 access_token_;
115  
116    // The current best position estimate.
117    Geoposition position_;
118  
119    // Whether permission has been granted for the provider to operate.
120    bool is_permission_granted_;
121  
122    bool is_new_data_available_;
123  
124    // The network location request object, and the url it uses.
125    scoped_ptr<NetworkLocationRequest> request_;
126  
127    // The cache of positions.
128    scoped_ptr<PositionCache> position_cache_;
129  
130    base::WeakPtrFactory<NetworkLocationProvider> weak_factory_;
131  
132    DISALLOW_COPY_AND_ASSIGN(NetworkLocationProvider);
133  };
134  
135  // Factory functions for the various types of location provider to abstract
136  // over the platform-dependent implementations.
137  CONTENT_EXPORT LocationProviderBase* NewNetworkLocationProvider(
138      AccessTokenStore* access_token_store,
139      net::URLRequestContextGetter* context,
140      const GURL& url,
141      const base::string16& access_token);
142  
143  }  // namespace content
144  
145  #endif  // CONTENT_BROWSER_GEOLOCATION_NETWORK_LOCATION_PROVIDER_H_
146