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 ANDROID_COMMON_CLOCK_SERVICE_H
18#define ANDROID_COMMON_CLOCK_SERVICE_H
19
20#include <sys/socket.h>
21#include <common_time/ICommonClock.h>
22
23namespace android {
24
25class CommonTimeServer;
26
27class CommonClockService : public BnCommonClock,
28                           public android::IBinder::DeathRecipient {
29  public:
30    static sp<CommonClockService> instantiate(CommonTimeServer& timeServer);
31
32    virtual status_t dump(int fd, const Vector<String16>& args);
33
34    virtual status_t isCommonTimeValid(bool* valid, uint32_t *timelineID);
35    virtual status_t commonTimeToLocalTime(int64_t  common_time,
36                                           int64_t* local_time);
37    virtual status_t localTimeToCommonTime(int64_t  local_time,
38                                           int64_t* common_time);
39    virtual status_t getCommonTime(int64_t* common_time);
40    virtual status_t getCommonFreq(uint64_t* freq);
41    virtual status_t getLocalTime(int64_t* local_time);
42    virtual status_t getLocalFreq(uint64_t* freq);
43    virtual status_t getEstimatedError(int32_t* estimate);
44    virtual status_t getTimelineID(uint64_t* id);
45    virtual status_t getState(ICommonClock::State* state);
46    virtual status_t getMasterAddr(struct sockaddr_storage* addr);
47
48    virtual status_t registerListener(
49            const sp<ICommonClockListener>& listener);
50    virtual status_t unregisterListener(
51            const sp<ICommonClockListener>& listener);
52
53    void notifyOnTimelineChanged(uint64_t timelineID);
54
55  private:
56    CommonClockService(CommonTimeServer& timeServer)
57        : mTimeServer(timeServer) { };
58
59    virtual void binderDied(const wp<IBinder>& who);
60
61    CommonTimeServer& mTimeServer;
62
63    // locks used to synchronize access to the list of registered listeners.
64    // The callback lock is held whenever the list is used to perform callbacks
65    // or while the list is being modified.  The registration lock used to
66    // serialize access across registerListener, unregisterListener, and
67    // binderDied.
68    //
69    // The reason for two locks is that registerListener, unregisterListener,
70    // and binderDied each call into the core service and obtain the core
71    // service thread lock when they call reevaluateAutoDisableState.  The core
72    // service thread obtains the main thread lock whenever its thread is
73    // running, and sometimes needs to call notifyOnTimelineChanged which then
74    // obtains the callback lock.  If callers of registration functions were
75    // holding the callback lock when they called into the core service, we
76    // would have a classic A/B, B/A ordering deadlock.  To avoid this, the
77    // registration functions hold the registration lock for the duration of
78    // their call, but hold the callback lock only while they mutate the list.
79    // This way, the list's size cannot change (because of the registration
80    // lock) during the call into reevaluateAutoDisableState, but the core work
81    // thread can still safely call notifyOnTimelineChanged while holding the
82    // main thread lock.
83    Mutex mCallbackLock;
84    Mutex mRegistrationLock;
85
86    Vector<sp<ICommonClockListener> > mListeners;
87};
88
89};  // namespace android
90
91#endif  // ANDROID_COMMON_CLOCK_SERVICE_H
92