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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef __CC_HELPER_H__
     18 #define __CC_HELPER_H__
     19 
     20 #include <stdint.h>
     21 #include <common_time/ICommonClock.h>
     22 #include <utils/threads.h>
     23 
     24 namespace android {
     25 
     26 // CCHelper is a simple wrapper class to help with centralizing access to the
     27 // Common Clock service and implementing lifetime managment, as well as to
     28 // implement a simple policy of making a basic attempt to reconnect to the
     29 // common clock service when things go wrong.
     30 //
     31 // On platforms which run the native common_time service in auto-disable mode,
     32 // the service will go into networkless mode whenever it has no active clients.
     33 // It tracks active clients using registered CommonClockListeners (the callback
     34 // interface for onTimelineChanged) since this provides a convienent death
     35 // handler notification for when the service's clients die unexpectedly.  This
     36 // means that users of the common time service should really always have a
     37 // CommonClockListener, unless they know that the time service is not running in
     38 // auto disabled mode, or that there is at least one other registered listener
     39 // active in the system.  The CCHelper makes this a little easier by sharing a
     40 // ref counted ICommonClock interface across all clients and automatically
     41 // registering and unregistering a listener whenever there are CCHelper
     42 // instances active in the process.
     43 class CCHelper {
     44   public:
     45     CCHelper();
     46     ~CCHelper();
     47 
     48     status_t isCommonTimeValid(bool* valid, uint32_t* timelineID);
     49     status_t commonTimeToLocalTime(int64_t commonTime, int64_t* localTime);
     50     status_t localTimeToCommonTime(int64_t localTime, int64_t* commonTime);
     51     status_t getCommonTime(int64_t* commonTime);
     52     status_t getCommonFreq(uint64_t* freq);
     53     status_t getLocalTime(int64_t* localTime);
     54     status_t getLocalFreq(uint64_t* freq);
     55 
     56   private:
     57     class CommonClockListener : public BnCommonClockListener {
     58       public:
     59         void onTimelineChanged(uint64_t timelineID);
     60     };
     61 
     62     static bool verifyClock_l();
     63 
     64     static Mutex lock_;
     65     static sp<ICommonClock> common_clock_;
     66     static sp<ICommonClockListener> common_clock_listener_;
     67     static uint32_t ref_count_;
     68 };
     69 
     70 
     71 }  // namespace android
     72 #endif  // __CC_HELPER_H__
     73