SF: Use VsyncSchedule's ID for EventThread

The existing code will take the first display that is hotplugged and set
it as the PhysicalDisplayId associated with the EventThread's future
vsync events. There isn't anything wrong with this in the current
implementation because SurfaceFlinger is careful about removing/adding
displays when pacesetter is changed.

The EventThread is already associated with a specific VsyncSchedule. The
VsyncSchedule already maintains the PhysicalDisplayId. Use that instead
and make the code slightly less fragile.

Bug: 352324977
Flag: EXEMPT refactor
Test: presubmit
Change-Id: I33d7da120289e5cf1127d783eae3011280bf65bd

Author: Ben Widawsky

services/surfaceflinger/Scheduler/EventThread.cpp

@@ -426,8 +426,8 @@ void EventThread::onVsync(nsecs_t vsyncTime, nsecs_t wakeupTime, nsecs_t readyTi
 
     LOG_FATAL_IF(!mVSyncState);
     mVsyncTracer = (mVsyncTracer + 1) % 2;
-    mPendingEvents.push_back(makeVSync(mVSyncState->displayId, wakeupTime, ++mVSyncState->count,
-                                       vsyncTime, readyTime));
+    mPendingEvents.push_back(makeVSync(mVsyncSchedule->getPhysicalDisplayId(), wakeupTime,
+                                       ++mVSyncState->count, vsyncTime, readyTime));
     mCondition.notify_all();
 }
 
@@ -486,9 +486,9 @@ void EventThread::threadMain(std::unique_lock<std::mutex>& lock) {
             if (event->header.type == DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG) {
                 if (event->hotplug.connectionError == 0) {
                     if (event->hotplug.connected && !mVSyncState) {
-                        mVSyncState.emplace(event->header.displayId);
-                    } else if (!event->hotplug.connected && mVSyncState &&
-                               mVSyncState->displayId == event->header.displayId) {
+                        mVSyncState.emplace();
+                    } else if (!event->hotplug.connected &&
+                               mVsyncSchedule->getPhysicalDisplayId() == event->header.displayId) {
                         mVSyncState.reset();
                     }
                 } else {
@@ -559,7 +559,7 @@ void EventThread::threadMain(std::unique_lock<std::mutex>& lock) {
                 const auto now = systemTime(SYSTEM_TIME_MONOTONIC);
                 const auto deadlineTimestamp = now + timeout.count();
                 const auto expectedVSyncTime = deadlineTimestamp + timeout.count();
-                mPendingEvents.push_back(makeVSync(mVSyncState->displayId, now,
+                mPendingEvents.push_back(makeVSync(mVsyncSchedule->getPhysicalDisplayId(), now,
                                                    ++mVSyncState->count, expectedVSyncTime,
                                                    deadlineTimestamp));
             }
@@ -739,7 +739,7 @@ void EventThread::dump(std::string& result) const {
     StringAppendF(&result, "%s: state=%s VSyncState=", mThreadName, toCString(mState));
     if (mVSyncState) {
         StringAppendF(&result, "{displayId=%s, count=%u%s}\n",
-                      to_string(mVSyncState->displayId).c_str(), mVSyncState->count,
+                      to_string(mVsyncSchedule->getPhysicalDisplayId()).c_str(), mVSyncState->count,
                       mVSyncState->synthetic ? ", synthetic" : "");
     } else {
         StringAppendF(&result, "none\n");

services/surfaceflinger/Scheduler/EventThread.h

@@ -235,10 +235,6 @@ class EventThread : public android::EventThread {
 
     // VSYNC state of connected display.
     struct VSyncState {
-        explicit VSyncState(PhysicalDisplayId displayId) : displayId(displayId) {}
-
-        const PhysicalDisplayId displayId;
-
         // Number of VSYNC events since display was connected.
         uint32_t count = 0;
 

services/surfaceflinger/Scheduler/VsyncSchedule.h

@@ -112,6 +112,8 @@ class VsyncSchedule final : public IVsyncSource {
 
     bool getPendingHardwareVsyncState() const REQUIRES(kMainThreadContext);
 
+    PhysicalDisplayId getPhysicalDisplayId() const { return mId; }
+
 protected:
     using ControllerPtr = std::unique_ptr<VsyncController>;