SF: Tie VSyncState lifetime to display hotplug

This CL creates/destroys EventThread::VSyncState when the display is
connected/disconnected.

Bug: 74619554
Test: libsurfaceflinger_unittest
Test: dumpsys SurfaceFlinger --vsync
Change-Id: I46dad4857222b6d2932ab568c4d66325edc3371b
diff --git a/services/surfaceflinger/Scheduler/EventThread.cpp b/services/surfaceflinger/Scheduler/EventThread.cpp
index 668dfd0..52abe9c 100644
--- a/services/surfaceflinger/Scheduler/EventThread.cpp
+++ b/services/surfaceflinger/Scheduler/EventThread.cpp
@@ -264,24 +264,29 @@
 
 void EventThread::onScreenReleased() {
     std::lock_guard<std::mutex> lock(mMutex);
-    if (!mVSyncState.synthetic) {
-        mVSyncState.synthetic = true;
-        mCondition.notify_all();
+    if (!mVSyncState || mVSyncState->synthetic) {
+        return;
     }
+
+    mVSyncState->synthetic = true;
+    mCondition.notify_all();
 }
 
 void EventThread::onScreenAcquired() {
     std::lock_guard<std::mutex> lock(mMutex);
-    if (mVSyncState.synthetic) {
-        mVSyncState.synthetic = false;
-        mCondition.notify_all();
+    if (!mVSyncState || !mVSyncState->synthetic) {
+        return;
     }
+
+    mVSyncState->synthetic = false;
+    mCondition.notify_all();
 }
 
 void EventThread::onVSyncEvent(nsecs_t timestamp) {
     std::lock_guard<std::mutex> lock(mMutex);
 
-    mPendingEvents.push_back(makeVSync(mVSyncState.displayId, timestamp, ++mVSyncState.count));
+    LOG_FATAL_IF(!mVSyncState);
+    mPendingEvents.push_back(makeVSync(mVSyncState->displayId, timestamp, ++mVSyncState->count));
     mCondition.notify_all();
 }
 
@@ -304,9 +309,21 @@
             event = mPendingEvents.front();
             mPendingEvents.pop_front();
 
-            if (mInterceptVSyncsCallback &&
-                event->header.type == DisplayEventReceiver::DISPLAY_EVENT_VSYNC) {
-                mInterceptVSyncsCallback(event->header.timestamp);
+            switch (event->header.type) {
+                case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
+                    if (event->hotplug.connected && !mVSyncState) {
+                        mVSyncState.emplace(event->header.id);
+                    } else if (!event->hotplug.connected && mVSyncState &&
+                               mVSyncState->displayId == event->header.id) {
+                        mVSyncState.reset();
+                    }
+                    break;
+
+                case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
+                    if (mInterceptVSyncsCallback) {
+                        mInterceptVSyncsCallback(event->header.timestamp);
+                    }
+                    break;
             }
         }
 
@@ -334,9 +351,10 @@
         }
 
         State nextState;
-        if (vsyncRequested) {
-            nextState = mVSyncState.synthetic ? State::SyntheticVSync : State::VSync;
+        if (mVSyncState && vsyncRequested) {
+            nextState = mVSyncState->synthetic ? State::SyntheticVSync : State::VSync;
         } else {
+            ALOGW_IF(!mVSyncState, "Ignoring VSYNC request while display is disconnected");
             nextState = State::Idle;
         }
 
@@ -364,9 +382,10 @@
             if (mCondition.wait_for(lock, timeout) == std::cv_status::timeout) {
                 ALOGW_IF(mState == State::VSync, "Faking VSYNC due to driver stall");
 
-                mPendingEvents.push_back(makeVSync(mVSyncState.displayId,
+                LOG_FATAL_IF(!mVSyncState);
+                mPendingEvents.push_back(makeVSync(mVSyncState->displayId,
                                                    systemTime(SYSTEM_TIME_MONOTONIC),
-                                                   ++mVSyncState.count));
+                                                   ++mVSyncState->count));
             }
         }
     }
@@ -419,9 +438,13 @@
 void EventThread::dump(std::string& result) const {
     std::lock_guard<std::mutex> lock(mMutex);
 
-    StringAppendF(&result, "%s: state=%s", mThreadName, toCString(mState));
-    StringAppendF(&result, " VSyncState{displayId=%u, count=%u%s}\n", mVSyncState.displayId,
-                  mVSyncState.count, mVSyncState.synthetic ? ", synthetic" : "");
+    StringAppendF(&result, "%s: state=%s VSyncState=", mThreadName, toCString(mState));
+    if (mVSyncState) {
+        StringAppendF(&result, "{displayId=%u, count=%u%s}\n", mVSyncState->displayId,
+                      mVSyncState->count, mVSyncState->synthetic ? ", synthetic" : "");
+    } else {
+        StringAppendF(&result, "none\n");
+    }
 
     StringAppendF(&result, "  pending events (count=%zu):\n", mPendingEvents.size());
     for (const auto& event : mPendingEvents) {
diff --git a/services/surfaceflinger/Scheduler/EventThread.h b/services/surfaceflinger/Scheduler/EventThread.h
index f093e47..89b799e 100644
--- a/services/surfaceflinger/Scheduler/EventThread.h
+++ b/services/surfaceflinger/Scheduler/EventThread.h
@@ -22,6 +22,7 @@
 #include <cstdint>
 #include <deque>
 #include <mutex>
+#include <optional>
 #include <thread>
 #include <vector>
 
@@ -198,7 +199,9 @@
 
     // VSYNC state of connected display.
     struct VSyncState {
-        uint32_t displayId = 0;
+        explicit VSyncState(uint32_t displayId) : displayId(displayId) {}
+
+        const uint32_t displayId;
 
         // Number of VSYNC events since display was connected.
         uint32_t count = 0;
@@ -207,7 +210,9 @@
         bool synthetic = false;
     };
 
-    VSyncState mVSyncState GUARDED_BY(mMutex);
+    // TODO(b/74619554): Create per-display threads waiting on respective VSYNC signals,
+    // and support headless mode by injecting a fake display with synthetic VSYNC.
+    std::optional<VSyncState> mVSyncState GUARDED_BY(mMutex);
 
     // State machine for event loop.
     enum class State {
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 14feb43..acf0013 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2564,6 +2564,17 @@
     mPendingHotplugEvents.clear();
 }
 
+void SurfaceFlinger::dispatchDisplayHotplugEvent(EventThread::DisplayType displayType,
+                                                 bool connected) {
+    if (mUseScheduler) {
+        mScheduler->hotplugReceived(mAppConnectionHandle, displayType, connected);
+        mScheduler->hotplugReceived(mSfConnectionHandle, displayType, connected);
+    } else {
+        mEventThread->onHotplugReceived(displayType, connected);
+        mSFEventThread->onHotplugReceived(displayType, connected);
+    }
+}
+
 sp<DisplayDevice> SurfaceFlinger::setupNewDisplayDeviceInternal(
         const wp<IBinder>& displayToken, const std::optional<DisplayId>& displayId,
         const DisplayDeviceState& state, const sp<compositionengine::DisplaySurface>& dispSurface,
@@ -2668,19 +2679,9 @@
                     display->disconnect();
                 }
                 if (internalDisplayId && internalDisplayId == draw[i].displayId) {
-                    if (mUseScheduler) {
-                        mScheduler->hotplugReceived(mAppConnectionHandle,
-                                                    EventThread::DisplayType::Primary, false);
-                    } else {
-                        mEventThread->onHotplugReceived(EventThread::DisplayType::Primary, false);
-                    }
+                    dispatchDisplayHotplugEvent(EventThread::DisplayType::Primary, false);
                 } else if (externalDisplayId && externalDisplayId == draw[i].displayId) {
-                    if (mUseScheduler) {
-                        mScheduler->hotplugReceived(mAppConnectionHandle,
-                                                    EventThread::DisplayType::External, false);
-                    } else {
-                        mEventThread->onHotplugReceived(EventThread::DisplayType::External, false);
-                    }
+                    dispatchDisplayHotplugEvent(EventThread::DisplayType::External, false);
                 }
                 mDisplays.erase(draw.keyAt(i));
             } else {
@@ -2786,23 +2787,9 @@
                         LOG_ALWAYS_FATAL_IF(!displayId);
 
                         if (displayId == getInternalDisplayId()) {
-                            if (mUseScheduler) {
-                                mScheduler->hotplugReceived(mAppConnectionHandle,
-                                                            EventThread::DisplayType::Primary,
-                                                            true);
-                            } else {
-                                mEventThread->onHotplugReceived(EventThread::DisplayType::Primary,
-                                                                true);
-                            }
+                            dispatchDisplayHotplugEvent(EventThread::DisplayType::Primary, true);
                         } else if (displayId == getExternalDisplayId()) {
-                            if (mUseScheduler) {
-                                mScheduler->hotplugReceived(mAppConnectionHandle,
-                                                            EventThread::DisplayType::External,
-                                                            true);
-                            } else {
-                                mEventThread->onHotplugReceived(EventThread::DisplayType::External,
-                                                                true);
-                            }
+                            dispatchDisplayHotplugEvent(EventThread::DisplayType::External, true);
                         }
                     }
                 }
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index c62f852..4d84144 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -294,10 +294,6 @@
     // starts SurfaceFlinger main loop in the current thread
     void run() ANDROID_API;
 
-    enum {
-        EVENT_VSYNC = HWC_EVENT_VSYNC
-    };
-
     // post an asynchronous message to the main thread
     status_t postMessageAsync(const sp<MessageBase>& msg, nsecs_t reltime = 0, uint32_t flags = 0);
 
@@ -754,6 +750,8 @@
     void processDisplayChangesLocked();
     void processDisplayHotplugEventsLocked();
 
+    void dispatchDisplayHotplugEvent(EventThread::DisplayType displayType, bool connected);
+
     /* ------------------------------------------------------------------------
      * VSync
      */
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
index 8201704..2c1833b 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
@@ -118,6 +118,7 @@
 
     TestableSurfaceFlinger mFlinger;
     mock::EventThread* mEventThread = new mock::EventThread();
+    mock::EventThread* mSFEventThread = new mock::EventThread();
     mock::EventControlThread* mEventControlThread = new mock::EventControlThread();
     sp<mock::NativeWindow> mNativeWindow = new mock::NativeWindow();
     sp<GraphicBuffer> mBuffer = new GraphicBuffer();
@@ -161,6 +162,7 @@
 
     mFlinger.mutableEventControlThread().reset(mEventControlThread);
     mFlinger.mutableEventThread().reset(mEventThread);
+    mFlinger.mutableSFEventThread().reset(mSFEventThread);
     mFlinger.mutableEventQueue().reset(mMessageQueue);
     mFlinger.setupRenderEngine(std::unique_ptr<renderengine::RenderEngine>(mRenderEngine));
     mFlinger.mutableInterceptor().reset(mSurfaceInterceptor);
@@ -319,6 +321,11 @@
     // Whether the display is primary
     static constexpr Primary PRIMARY = primary;
 
+    static constexpr auto displayType() {
+        return static_cast<bool>(PRIMARY) ? EventThread::DisplayType::Primary
+                                          : EventThread::DisplayType::External;
+    }
+
     static auto makeFakeExistingDisplayInjector(DisplayTransactionTest* test) {
         auto injector =
                 FakeDisplayDeviceInjector(test->mFlinger, DISPLAY_ID::get(),
@@ -1404,23 +1411,17 @@
     Case::PerFrameMetadataSupport::setupComposerCallExpectations(this);
 
     EXPECT_CALL(*mSurfaceInterceptor, saveDisplayCreation(_)).Times(1);
-    EXPECT_CALL(*mEventThread,
-                onHotplugReceived(static_cast<bool>(Case::Display::PRIMARY)
-                                          ? EventThread::DisplayType::Primary
-                                          : EventThread::DisplayType::External,
-                                  true))
-            .Times(1);
+
+    EXPECT_CALL(*mEventThread, onHotplugReceived(Case::Display::displayType(), true)).Times(1);
+    EXPECT_CALL(*mSFEventThread, onHotplugReceived(Case::Display::displayType(), true)).Times(1);
 }
 
 template <typename Case>
 void HandleTransactionLockedTest::setupCommonCallExpectationsForDisconnectProcessing() {
     EXPECT_CALL(*mSurfaceInterceptor, saveDisplayDeletion(_)).Times(1);
-    EXPECT_CALL(*mEventThread,
-                onHotplugReceived(static_cast<bool>(Case::Display::PRIMARY)
-                                          ? EventThread::DisplayType::Primary
-                                          : EventThread::DisplayType::External,
-                                  false))
-            .Times(1);
+
+    EXPECT_CALL(*mEventThread, onHotplugReceived(Case::Display::displayType(), false)).Times(1);
+    EXPECT_CALL(*mSFEventThread, onHotplugReceived(Case::Display::displayType(), false)).Times(1);
 }
 
 template <typename Case>
diff --git a/services/surfaceflinger/tests/unittests/EventThreadTest.cpp b/services/surfaceflinger/tests/unittests/EventThreadTest.cpp
index e6cdd02..79fb034 100644
--- a/services/surfaceflinger/tests/unittests/EventThreadTest.cpp
+++ b/services/surfaceflinger/tests/unittests/EventThreadTest.cpp
@@ -104,6 +104,10 @@
 
     createThread();
     mConnection = createConnection(mConnectionEventCallRecorder);
+
+    // A display must be connected for VSYNC events to be delivered.
+    mThread->onHotplugReceived(EventThread::DisplayType::Primary, true);
+    expectHotplugEventReceivedByConnection(EventThread::DisplayType::Primary, true);
 }
 
 EventThreadTest::~EventThreadTest() {
@@ -207,6 +211,23 @@
     EXPECT_FALSE(mConnectionEventCallRecorder.waitForCall(0us).has_value());
 }
 
+TEST_F(EventThreadTest, vsyncRequestIsIgnoredIfDisplayIsDisconnected) {
+    mThread->onHotplugReceived(EventThread::DisplayType::Primary, false);
+    expectHotplugEventReceivedByConnection(EventThread::DisplayType::Primary, false);
+
+    // Signal that we want the next vsync event to be posted to the connection.
+    mThread->requestNextVsync(mConnection, false);
+
+    // EventThread should not enable vsync callbacks.
+    EXPECT_FALSE(mVSyncSetEnabledCallRecorder.waitForUnexpectedCall().has_value());
+
+    // Use the received callback to signal a vsync event.
+    // The event should not be received by the interceptor nor the connection.
+    mCallback->onVSyncEvent(123);
+    EXPECT_FALSE(mInterceptVSyncCallRecorder.waitForCall(0us).has_value());
+    EXPECT_FALSE(mConnectionEventCallRecorder.waitForCall(0us).has_value());
+}
+
 TEST_F(EventThreadTest, requestNextVsyncPostsASingleVSyncEventToTheConnection) {
     // Signal that we want the next vsync event to be posted to the connection
     mThread->requestNextVsync(mConnection, false);
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index 2a8dda6..9c5c967 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -290,6 +290,7 @@
     auto& mutableEventControlThread() { return mFlinger->mEventControlThread; }
     auto& mutableEventQueue() { return mFlinger->mEventQueue; }
     auto& mutableEventThread() { return mFlinger->mEventThread; }
+    auto& mutableSFEventThread() { return mFlinger->mSFEventThread; }
     auto& mutableGeometryInvalid() { return mFlinger->mGeometryInvalid; }
     auto& mutableHWVsyncAvailable() { return mFlinger->mHWVsyncAvailable; }
     auto& mutableInterceptor() { return mFlinger->mInterceptor; }
@@ -317,6 +318,7 @@
         mutableEventControlThread().reset();
         mutableEventQueue().reset();
         mutableEventThread().reset();
+        mutableSFEventThread().reset();
         mutableInterceptor().reset();
         mutablePrimaryDispSync().reset();
         mFlinger->mCompositionEngine->setHwComposer(std::unique_ptr<HWComposer>());