1 /*
2  * Copyright 2018 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 #pragma once
18 
19 #include <chrono>
20 #include <mutex>
21 #include <optional>
22 #include <unordered_set>
23 
24 #include <android-base/thread_annotations.h>
25 #include <binder/IBinder.h>
26 #include <utils/Timers.h>
27 
28 #include <scheduler/TransactionSchedule.h>
29 #include <scheduler/VsyncConfig.h>
30 
31 #include "../WpHash.h"
32 
33 namespace android::scheduler {
34 
35 // Modulates VSYNC phase depending on transaction schedule and refresh rate changes.
36 class VsyncModulator : public IBinder::DeathRecipient {
37 public:
38     // Number of frames to keep early offsets after an early transaction or GPU composition.
39     // This acts as a low-pass filter in case subsequent transactions are delayed, or if the
40     // composition strategy alternates on subsequent frames.
41     static constexpr int MIN_EARLY_TRANSACTION_FRAMES = 2;
42     static constexpr int MIN_EARLY_GPU_FRAMES = 2;
43 
44     // Duration to delay the MIN_EARLY_TRANSACTION_FRAMES countdown after an early transaction.
45     // This may keep early offsets for an extra frame, but avoids a race with transaction commit.
46     static const std::chrono::nanoseconds MIN_EARLY_TRANSACTION_TIME;
47 
48     using VsyncConfigOpt = std::optional<VsyncConfig>;
49 
50     using Clock = std::chrono::steady_clock;
51     using TimePoint = Clock::time_point;
52     using Now = TimePoint (*)();
53 
54     explicit VsyncModulator(const VsyncConfigSet&, Now = Clock::now);
55 
56     bool isVsyncConfigEarly() const EXCLUDES(mMutex);
57 
58     VsyncConfig getVsyncConfig() const EXCLUDES(mMutex);
59 
cancelRefreshRateChange()60     void cancelRefreshRateChange() { mRefreshRateChangePending = false; }
61 
62     [[nodiscard]] VsyncConfig setVsyncConfigSet(const VsyncConfigSet&) EXCLUDES(mMutex);
63 
64     // Changes offsets in response to transaction flags or commit.
65     [[nodiscard]] VsyncConfigOpt setTransactionSchedule(TransactionSchedule,
66                                                         const sp<IBinder>& = {}) EXCLUDES(mMutex);
67     [[nodiscard]] VsyncConfigOpt onTransactionCommit();
68 
69     // Called when we send a refresh rate change to hardware composer, so that
70     // we can move into early offsets.
71     [[nodiscard]] VsyncConfigOpt onRefreshRateChangeInitiated();
72 
73     // Called when we detect from VSYNC signals that the refresh rate changed.
74     // This way we can move out of early offsets if no longer necessary.
75     [[nodiscard]] VsyncConfigOpt onRefreshRateChangeCompleted();
76 
77     [[nodiscard]] VsyncConfigOpt onDisplayRefresh(bool usedGpuComposition);
78 
79 protected:
80     // Called from unit tests as well
81     void binderDied(const wp<IBinder>&) override EXCLUDES(mMutex);
82 
83 private:
84     enum class VsyncConfigType { Early, EarlyGpu, Late };
85 
86     VsyncConfigType getNextVsyncConfigType() const REQUIRES(mMutex);
87     const VsyncConfig& getNextVsyncConfig() const REQUIRES(mMutex);
88     [[nodiscard]] VsyncConfig updateVsyncConfig() EXCLUDES(mMutex);
89     [[nodiscard]] VsyncConfig updateVsyncConfigLocked() REQUIRES(mMutex);
90 
91     mutable std::mutex mMutex;
92     VsyncConfigSet mVsyncConfigSet GUARDED_BY(mMutex);
93 
GUARDED_BY(mMutex)94     VsyncConfig mVsyncConfig GUARDED_BY(mMutex){mVsyncConfigSet.late};
95 
96     using Schedule = TransactionSchedule;
97     std::atomic<Schedule> mTransactionSchedule = Schedule::Late;
98 
99     std::unordered_set<wp<IBinder>, WpHash> mEarlyWakeupRequests GUARDED_BY(mMutex);
100     std::atomic<bool> mRefreshRateChangePending = false;
101 
102     std::atomic<int> mEarlyTransactionFrames = 0;
103     std::atomic<int> mEarlyGpuFrames = 0;
104     std::atomic<TimePoint> mEarlyTransactionStartTime = TimePoint();
105     std::atomic<TimePoint> mLastTransactionCommitTime = TimePoint();
106 
107     const Now mNow;
108     const bool mTraceDetailedInfo;
109 };
110 
111 } // namespace android::scheduler
112