1 /*
2  * Copyright 2010, The Android Open Source Project
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *  * Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  *  * Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #ifndef GeolocationPositionCache_h
27 #define GeolocationPositionCache_h
28 
29 #include "PlatformString.h"
30 #include "ScriptExecutionContext.h"
31 
32 #include <wtf/Forward.h>
33 #include <wtf/MessageQueue.h>
34 #include <wtf/PassRefPtr.h>
35 #include <wtf/RefPtr.h>
36 
37 namespace WebCore {
38 
39 class Geoposition;
40 
41 // Maintains a cached position for Geolocation. Takes care of writing and
42 // reading the position to a database on a background thread. The Geolocation
43 // spec does not require a cached position to be maintained, so we take a
44 // best-effort approach where we do not wait for database reads or writes.
45 class GeolocationPositionCache {
46 public:
47     static GeolocationPositionCache* instance();
48 
49     void addUser();
50     void removeUser();
51 
52     void setDatabasePath(const String&);
53     void setCachedPosition(Geoposition*);
54     Geoposition* cachedPosition();
55 
56 private:
57     GeolocationPositionCache();
58 
59     void startBackgroundThread();
60     static void* threadEntryPoint(void* object);
61     void threadEntryPointImpl();
62 
63     void triggerReadFromDatabase();
64     static void readFromDatabase(ScriptExecutionContext*, GeolocationPositionCache*);
65     void readFromDatabaseImpl();
66     void triggerWriteToDatabase();
67     static void writeToDatabase(ScriptExecutionContext*, GeolocationPositionCache*);
68     void writeToDatabaseImpl();
69 
70     RefPtr<Geoposition> m_cachedPosition;
71     Mutex m_cachedPositionMutex;
72     ThreadIdentifier m_threadId;
73     MessageQueue<ScriptExecutionContext::Task> m_queue;
74     String m_databaseFile;
75     Mutex m_databaseFileMutex;
76 };
77 
78 } // namespace WebCore
79 
80 #endif // GeolocationPositionCache_h
81