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      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