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