Revert "Revert "SF: pass a render rate to VsyncTracker instead of a divisor""

This reverts commit 3d21d3afa1056efacf702b74449f9e2e7b5701f1.

Reason for revert: https://b.corp.google.com/issues/269561042#comment14

Bug: 269561042
Change-Id: Iae8d0e62be2eafb4278b64ffcb1524ece211a00c
diff --git a/services/surfaceflinger/Scheduler/Scheduler.cpp b/services/surfaceflinger/Scheduler/Scheduler.cpp
index 17cdff9..dab01ba 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.cpp
+++ b/services/surfaceflinger/Scheduler/Scheduler.cpp
@@ -418,11 +418,7 @@
     ALOGV("%s %s (%s)", __func__, to_string(mode.fps).c_str(),
           to_string(mode.modePtr->getFps()).c_str());
 
-    const auto divisor = RefreshRateSelector::getFrameRateDivisor(mode.modePtr->getFps(), mode.fps);
-    LOG_ALWAYS_FATAL_IF(divisor == 0, "%s <> %s -- not divisors", to_string(mode.fps).c_str(),
-                        to_string(mode.fps).c_str());
-
-    mVsyncSchedule->getTracker().setDivisor(static_cast<unsigned>(divisor));
+    mVsyncSchedule->getTracker().setRenderRate(renderFrameRate);
 }
 
 void Scheduler::resync() {
diff --git a/services/surfaceflinger/Scheduler/VSyncPredictor.cpp b/services/surfaceflinger/Scheduler/VSyncPredictor.cpp
index 5a5afd8..de7b338 100644
--- a/services/surfaceflinger/Scheduler/VSyncPredictor.cpp
+++ b/services/surfaceflinger/Scheduler/VSyncPredictor.cpp
@@ -272,13 +272,26 @@
     // update the mLastVsyncSequence for reference point
     mLastVsyncSequence = getVsyncSequenceLocked(timePoint);
 
-    const auto mod = mLastVsyncSequence->seq % mDivisor;
-    if (mod == 0) {
+    const auto renderRatePhase = [&]() REQUIRES(mMutex) -> int {
+        if (!mRenderRate) return 0;
+
+        const auto divisor =
+                RefreshRateSelector::getFrameRateDivisor(Fps::fromPeriodNsecs(mIdealPeriod),
+                                                         *mRenderRate);
+        if (divisor <= 1) return 0;
+
+        const int mod = mLastVsyncSequence->seq % divisor;
+        if (mod == 0) return 0;
+
+        return divisor - mod;
+    }();
+
+    if (renderRatePhase == 0) {
         return mLastVsyncSequence->vsyncTime;
     }
 
     auto const [slope, intercept] = getVSyncPredictionModelLocked();
-    const auto approximateNextVsync = mLastVsyncSequence->vsyncTime + slope * (mDivisor - mod);
+    const auto approximateNextVsync = mLastVsyncSequence->vsyncTime + slope * renderRatePhase;
     return nextAnticipatedVSyncTimeFromLocked(approximateNextVsync - slope / 2);
 }
 
@@ -317,10 +330,10 @@
     return vsyncSequence.seq % divisor == 0;
 }
 
-void VSyncPredictor::setDivisor(unsigned divisor) {
-    ALOGV("%s: %d", __func__, divisor);
+void VSyncPredictor::setRenderRate(Fps fps) {
+    ALOGV("%s: %s", __func__, to_string(fps).c_str());
     std::lock_guard lock(mMutex);
-    mDivisor = divisor;
+    mRenderRate = fps;
 }
 
 VSyncPredictor::Model VSyncPredictor::getVSyncPredictionModel() const {
diff --git a/services/surfaceflinger/Scheduler/VSyncPredictor.h b/services/surfaceflinger/Scheduler/VSyncPredictor.h
index d0e3098..cd5d9ef 100644
--- a/services/surfaceflinger/Scheduler/VSyncPredictor.h
+++ b/services/surfaceflinger/Scheduler/VSyncPredictor.h
@@ -67,7 +67,7 @@
 
     bool isVSyncInPhase(nsecs_t timePoint, Fps frameRate) const final EXCLUDES(mMutex);
 
-    void setDivisor(unsigned divisor) final EXCLUDES(mMutex);
+    void setRenderRate(Fps) final EXCLUDES(mMutex);
 
     void dump(std::string& result) const final EXCLUDES(mMutex);
 
@@ -106,7 +106,7 @@
     size_t mLastTimestampIndex GUARDED_BY(mMutex) = 0;
     std::vector<nsecs_t> mTimestamps GUARDED_BY(mMutex);
 
-    unsigned mDivisor GUARDED_BY(mMutex) = 1;
+    std::optional<Fps> mRenderRate GUARDED_BY(mMutex);
 
     mutable std::optional<VsyncSequence> mLastVsyncSequence GUARDED_BY(mMutex);
 };
diff --git a/services/surfaceflinger/Scheduler/VSyncTracker.h b/services/surfaceflinger/Scheduler/VSyncTracker.h
index 8d1629f..bc0e3bc 100644
--- a/services/surfaceflinger/Scheduler/VSyncTracker.h
+++ b/services/surfaceflinger/Scheduler/VSyncTracker.h
@@ -80,15 +80,16 @@
     virtual bool isVSyncInPhase(nsecs_t timePoint, Fps frameRate) const = 0;
 
     /*
-     * Sets a divisor on the rate (which is a multiplier of the period).
+     * Sets a render rate on the tracker. If the render rate is not a divisor
+     * of the period, the render rate is ignored until the period changes.
      * The tracker will continue to track the vsync timeline and expect it
      * to match the current period, however, nextAnticipatedVSyncTimeFrom will
-     * return vsyncs according to the divisor set. Setting a divisor is useful
+     * return vsyncs according to the render rate set. Setting a render rate is useful
      * when a display is running at 120Hz but the render frame rate is 60Hz.
      *
-     * \param [in] divisor   The rate divisor the tracker should operate at.
+     * \param [in] Fps   The render rate the tracker should operate at.
      */
-    virtual void setDivisor(unsigned divisor) = 0;
+    virtual void setRenderRate(Fps) = 0;
 
     virtual void dump(std::string& result) const = 0;
 
diff --git a/services/surfaceflinger/fuzzer/surfaceflinger_scheduler_fuzzer.h b/services/surfaceflinger/fuzzer/surfaceflinger_scheduler_fuzzer.h
index 713b710..e6be9a8 100644
--- a/services/surfaceflinger/fuzzer/surfaceflinger_scheduler_fuzzer.h
+++ b/services/surfaceflinger/fuzzer/surfaceflinger_scheduler_fuzzer.h
@@ -100,7 +100,7 @@
         return true;
     }
 
-    void setDivisor(unsigned) override {}
+    void setRenderRate(Fps) override {}
 
     nsecs_t nextVSyncTime(nsecs_t timePoint) const {
         if (timePoint % mPeriod == 0) {
diff --git a/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp b/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp
index 47c2dee..2908834 100644
--- a/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncDispatchRealtimeTest.cpp
@@ -54,7 +54,7 @@
     void resetModel() final {}
     bool needsMoreSamples() const final { return false; }
     bool isVSyncInPhase(nsecs_t, Fps) const final { return false; }
-    void setDivisor(unsigned) final {}
+    void setRenderRate(Fps) final {}
     void dump(std::string&) const final {}
 
 private:
@@ -92,7 +92,7 @@
     void resetModel() final {}
     bool needsMoreSamples() const final { return false; }
     bool isVSyncInPhase(nsecs_t, Fps) const final { return false; }
-    void setDivisor(unsigned) final {}
+    void setRenderRate(Fps) final {}
     void dump(std::string&) const final {}
 
 private:
diff --git a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
index 14a2860..f143b49 100644
--- a/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncDispatchTimerQueueTest.cpp
@@ -55,7 +55,7 @@
     MOCK_METHOD0(resetModel, void());
     MOCK_CONST_METHOD0(needsMoreSamples, bool());
     MOCK_CONST_METHOD2(isVSyncInPhase, bool(nsecs_t, Fps));
-    MOCK_METHOD(void, setDivisor, (unsigned), (override));
+    MOCK_METHOD(void, setRenderRate, (Fps), (override));
     MOCK_CONST_METHOD1(dump, void(std::string&));
 
     nsecs_t nextVSyncTime(nsecs_t timePoint) const {
diff --git a/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp b/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
index 48d39cf..db531bf 100644
--- a/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncPredictorTest.cpp
@@ -554,7 +554,7 @@
     EXPECT_THAT(intercept, IsCloseTo(expectedIntercept, mMaxRoundingError));
 }
 
-TEST_F(VSyncPredictorTest, setDivisorIsRespected) {
+TEST_F(VSyncPredictorTest, setRenderRateIsRespected) {
     auto last = mNow;
     for (auto i = 0u; i < kMinimumSamplesForPrediction; i++) {
         EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow), Eq(last + mPeriod));
@@ -563,7 +563,7 @@
         tracker.addVsyncTimestamp(mNow);
     }
 
-    tracker.setDivisor(3);
+    tracker.setRenderRate(Fps::fromPeriodNsecs(3 * mPeriod));
 
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow), Eq(mNow + mPeriod));
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 100), Eq(mNow + mPeriod));
@@ -574,7 +574,7 @@
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 5100), Eq(mNow + 7 * mPeriod));
 }
 
-TEST_F(VSyncPredictorTest, setDivisorOfDivosorIsInPhase) {
+TEST_F(VSyncPredictorTest, setRenderRateOfDivisorIsInPhase) {
     auto last = mNow;
     for (auto i = 0u; i < kMinimumSamplesForPrediction; i++) {
         EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow), Eq(last + mPeriod));
@@ -583,18 +583,44 @@
         tracker.addVsyncTimestamp(mNow);
     }
 
-    tracker.setDivisor(4);
+    const auto refreshRate = Fps::fromPeriodNsecs(mPeriod);
+
+    tracker.setRenderRate(refreshRate / 4);
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow), Eq(mNow + 3 * mPeriod));
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 3 * mPeriod), Eq(mNow + 7 * mPeriod));
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 7 * mPeriod), Eq(mNow + 11 * mPeriod));
 
-    tracker.setDivisor(2);
+    tracker.setRenderRate(refreshRate / 2);
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow), Eq(mNow + 1 * mPeriod));
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 1 * mPeriod), Eq(mNow + 3 * mPeriod));
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 3 * mPeriod), Eq(mNow + 5 * mPeriod));
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 5 * mPeriod), Eq(mNow + 7 * mPeriod));
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 7 * mPeriod), Eq(mNow + 9 * mPeriod));
     EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 9 * mPeriod), Eq(mNow + 11 * mPeriod));
+
+    tracker.setRenderRate(refreshRate / 6);
+    EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow), Eq(mNow + 1 * mPeriod));
+    EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 1 * mPeriod), Eq(mNow + 7 * mPeriod));
+}
+
+TEST_F(VSyncPredictorTest, setRenderRateIsIgnoredIfNotDivisor) {
+    auto last = mNow;
+    for (auto i = 0u; i < kMinimumSamplesForPrediction; i++) {
+        EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow), Eq(last + mPeriod));
+        mNow += mPeriod;
+        last = mNow;
+        tracker.addVsyncTimestamp(mNow);
+    }
+
+    tracker.setRenderRate(Fps::fromPeriodNsecs(3.5f * mPeriod));
+
+    EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow), Eq(mNow + mPeriod));
+    EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 100), Eq(mNow + mPeriod));
+    EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 1100), Eq(mNow + 2 * mPeriod));
+    EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 2100), Eq(mNow + 3 * mPeriod));
+    EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 3100), Eq(mNow + 4 * mPeriod));
+    EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 4100), Eq(mNow + 5 * mPeriod));
+    EXPECT_THAT(tracker.nextAnticipatedVSyncTimeFrom(mNow + 5100), Eq(mNow + 6 * mPeriod));
 }
 
 } // namespace android::scheduler
diff --git a/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp b/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp
index 1fb2709..fb8d989 100644
--- a/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp
+++ b/services/surfaceflinger/tests/unittests/VSyncReactorTest.cpp
@@ -50,7 +50,7 @@
     MOCK_METHOD0(resetModel, void());
     MOCK_CONST_METHOD0(needsMoreSamples, bool());
     MOCK_CONST_METHOD2(isVSyncInPhase, bool(nsecs_t, Fps));
-    MOCK_METHOD(void, setDivisor, (unsigned), (override));
+    MOCK_METHOD(void, setRenderRate, (Fps), (override));
     MOCK_CONST_METHOD1(dump, void(std::string&));
 };
 
diff --git a/services/surfaceflinger/tests/unittests/mock/MockVSyncTracker.h b/services/surfaceflinger/tests/unittests/mock/MockVSyncTracker.h
index 6893154..dcf25e1 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockVSyncTracker.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockVSyncTracker.h
@@ -34,7 +34,7 @@
     MOCK_METHOD0(resetModel, void());
     MOCK_CONST_METHOD0(needsMoreSamples, bool());
     MOCK_CONST_METHOD2(isVSyncInPhase, bool(nsecs_t, Fps));
-    MOCK_METHOD(void, setDivisor, (unsigned), (override));
+    MOCK_METHOD(void, setRenderRate, (Fps), (override));
     MOCK_CONST_METHOD1(dump, void(std::string&));
 };