Expose gl/hwc switch counts from timestats.

The intention is that this counter will be used as a drilldown metric in
jank-type tests, as an increase in the change of composition strategy
may correlate with an increase of missed frames.

Bug: 144526027
Test: adb shell dumpsys SurfaceFlinger --timestats -dump
Change-Id: I01994a7d376fb67422563d65b8675457497b4807
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index ddf0775..82fb99e 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2084,6 +2084,8 @@
     postFrame();
     postComposition();
 
+    const bool prevFrameHadDeviceComposition = mHadDeviceComposition;
+
     mHadClientComposition =
             std::any_of(mDisplays.cbegin(), mDisplays.cend(), [](const auto& tokenDisplayPair) {
                 auto& displayDevice = tokenDisplayPair.second;
@@ -2101,6 +2103,11 @@
                 return displayDevice->getCompositionDisplay()->getState().reusedClientComposition;
             });
 
+    // Only report a strategy change if we move in and out of composition with hw overlays
+    if (prevFrameHadDeviceComposition != mHadDeviceComposition) {
+        mTimeStats->incrementCompositionStrategyChanges();
+    }
+
     mVSyncModulator->onRefreshed(mHadClientComposition);
 
     mLayersWithQueuedFrames.clear();
diff --git a/services/surfaceflinger/TimeStats/TimeStats.cpp b/services/surfaceflinger/TimeStats/TimeStats.cpp
index 606e137..80fe180 100644
--- a/services/surfaceflinger/TimeStats/TimeStats.cpp
+++ b/services/surfaceflinger/TimeStats/TimeStats.cpp
@@ -290,6 +290,15 @@
     mTimeStats.refreshRateSwitches++;
 }
 
+void TimeStats::incrementCompositionStrategyChanges() {
+    if (!mEnabled.load()) return;
+
+    ATRACE_CALL();
+
+    std::lock_guard<std::mutex> lock(mMutex);
+    mTimeStats.compositionStrategyChanges++;
+}
+
 void TimeStats::recordDisplayEventConnectionCount(int32_t count) {
     if (!mEnabled.load()) return;
 
@@ -844,6 +853,7 @@
     mTimeStats.clientCompositionFrames = 0;
     mTimeStats.clientCompositionReusedFrames = 0;
     mTimeStats.refreshRateSwitches = 0;
+    mTimeStats.compositionStrategyChanges = 0;
     mTimeStats.displayEventConnectionsCount = 0;
     mTimeStats.displayOnTime = 0;
     mTimeStats.presentToPresent.hist.clear();
diff --git a/services/surfaceflinger/TimeStats/TimeStats.h b/services/surfaceflinger/TimeStats/TimeStats.h
index 806b47e..eb48353 100644
--- a/services/surfaceflinger/TimeStats/TimeStats.h
+++ b/services/surfaceflinger/TimeStats/TimeStats.h
@@ -54,6 +54,10 @@
     virtual void incrementClientCompositionReusedFrames() = 0;
     // Increments the number of times the display refresh rate changed.
     virtual void incrementRefreshRateSwitches() = 0;
+    // Increments the number of changes in composition strategy
+    // The intention is to reflect the number of changes between hwc and gpu
+    // composition, where "gpu composition" may also include mixed composition.
+    virtual void incrementCompositionStrategyChanges() = 0;
     // Records the most up-to-date count of display event connections.
     // The stored count will be the maximum ever recoded.
     virtual void recordDisplayEventConnectionCount(int32_t count) = 0;
@@ -218,6 +222,7 @@
     void incrementClientCompositionFrames() override;
     void incrementClientCompositionReusedFrames() override;
     void incrementRefreshRateSwitches() override;
+    void incrementCompositionStrategyChanges() override;
     void recordDisplayEventConnectionCount(int32_t count) override;
 
     void recordFrameDuration(nsecs_t startTime, nsecs_t endTime) override;
diff --git a/services/surfaceflinger/TimeStats/timestatsproto/TimeStatsHelper.cpp b/services/surfaceflinger/TimeStats/timestatsproto/TimeStatsHelper.cpp
index 5305de9..c90b1b8 100644
--- a/services/surfaceflinger/TimeStats/timestatsproto/TimeStatsHelper.cpp
+++ b/services/surfaceflinger/TimeStats/timestatsproto/TimeStatsHelper.cpp
@@ -106,6 +106,7 @@
     StringAppendF(&result, "clientCompositionFrames = %d\n", clientCompositionFrames);
     StringAppendF(&result, "clientCompositionReusedFrames = %d\n", clientCompositionReusedFrames);
     StringAppendF(&result, "refreshRateSwitches = %d\n", refreshRateSwitches);
+    StringAppendF(&result, "compositionStrategyChanges = %d\n", compositionStrategyChanges);
     StringAppendF(&result, "displayOnTime = %" PRId64 " ms\n", displayOnTime);
     StringAppendF(&result, "displayConfigStats is as below:\n");
     for (const auto& [fps, duration] : refreshRateStats) {
diff --git a/services/surfaceflinger/TimeStats/timestatsproto/include/timestatsproto/TimeStatsHelper.h b/services/surfaceflinger/TimeStats/timestatsproto/include/timestatsproto/TimeStatsHelper.h
index afb98e0..0c75f96 100644
--- a/services/surfaceflinger/TimeStats/timestatsproto/include/timestatsproto/TimeStatsHelper.h
+++ b/services/surfaceflinger/TimeStats/timestatsproto/include/timestatsproto/TimeStatsHelper.h
@@ -63,6 +63,7 @@
         int32_t clientCompositionFrames = 0;
         int32_t clientCompositionReusedFrames = 0;
         int32_t refreshRateSwitches = 0;
+        int32_t compositionStrategyChanges = 0;
         int32_t displayEventConnectionsCount = 0;
         int64_t displayOnTime = 0;
         Histogram presentToPresent;
diff --git a/services/surfaceflinger/tests/unittests/TimeStatsTest.cpp b/services/surfaceflinger/tests/unittests/TimeStatsTest.cpp
index 1f04673..5de6bac 100644
--- a/services/surfaceflinger/tests/unittests/TimeStatsTest.cpp
+++ b/services/surfaceflinger/tests/unittests/TimeStatsTest.cpp
@@ -377,6 +377,21 @@
     EXPECT_THAT(result, HasSubstr(expectedResult));
 }
 
+TEST_F(TimeStatsTest, canIncreaseCompositionStrategyChanges) {
+    // this stat is not in the proto so verify by checking the string dump
+    constexpr size_t COMPOSITION_STRATEGY_CHANGES = 2;
+
+    EXPECT_TRUE(inputCommand(InputCommand::ENABLE, FMT_STRING).empty());
+    for (size_t i = 0; i < COMPOSITION_STRATEGY_CHANGES; i++) {
+        ASSERT_NO_FATAL_FAILURE(mTimeStats->incrementCompositionStrategyChanges());
+    }
+
+    const std::string result(inputCommand(InputCommand::DUMP_ALL, FMT_STRING));
+    const std::string expectedResult =
+            "compositionStrategyChanges = " + std::to_string(COMPOSITION_STRATEGY_CHANGES);
+    EXPECT_THAT(result, HasSubstr(expectedResult));
+}
+
 TEST_F(TimeStatsTest, canAverageFrameDuration) {
     EXPECT_TRUE(inputCommand(InputCommand::ENABLE, FMT_STRING).empty());
     mTimeStats->setPowerMode(HWC_POWER_MODE_NORMAL);
@@ -760,6 +775,7 @@
     EXPECT_TRUE(inputCommand(InputCommand::ENABLE, FMT_STRING).empty());
     ASSERT_NO_FATAL_FAILURE(mTimeStats->incrementClientCompositionReusedFrames());
     ASSERT_NO_FATAL_FAILURE(mTimeStats->incrementRefreshRateSwitches());
+    ASSERT_NO_FATAL_FAILURE(mTimeStats->incrementCompositionStrategyChanges());
     mTimeStats->setPowerMode(HWC_POWER_MODE_NORMAL);
     mTimeStats
             ->recordFrameDuration(std::chrono::duration_cast<std::chrono::nanoseconds>(1ms).count(),
@@ -776,6 +792,7 @@
     const std::string result(inputCommand(InputCommand::DUMP_ALL, FMT_STRING));
     EXPECT_THAT(result, HasSubstr("clientCompositionReusedFrames = 0"));
     EXPECT_THAT(result, HasSubstr("refreshRateSwitches = 0"));
+    EXPECT_THAT(result, HasSubstr("compositionStrategyChanges = 0"));
     EXPECT_THAT(result, HasSubstr("averageFrameDuration = 0.000 ms"));
     EXPECT_THAT(result, HasSubstr("averageRenderEngineTiming = 0.000 ms"));
 }
diff --git a/services/surfaceflinger/tests/unittests/mock/MockTimeStats.h b/services/surfaceflinger/tests/unittests/mock/MockTimeStats.h
index 9ea4dd0..dca1070 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockTimeStats.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockTimeStats.h
@@ -37,6 +37,7 @@
     MOCK_METHOD0(incrementClientCompositionFrames, void());
     MOCK_METHOD0(incrementClientCompositionReusedFrames, void());
     MOCK_METHOD0(incrementRefreshRateSwitches, void());
+    MOCK_METHOD0(incrementCompositionStrategyChanges, void());
     MOCK_METHOD1(recordDisplayEventConnectionCount, void(int32_t));
     MOCK_METHOD2(recordFrameDuration, void(nsecs_t, nsecs_t));
     MOCK_METHOD2(recordRenderEngineDuration, void(nsecs_t, nsecs_t));