SurfaceFlinger: Add DISPLAY_EVENT_FRAME_RATE_OVERRIDE

Add a new event to DisplayEventReceiver that conveys a list
of apps whose frame rates have been overriden.
This event is processed by the DisplayManager to advertise the
new frame rate to the overridden app.

Change-Id: I89fce8b5b4d9db65ec5db7dd2393c384c0fcfd82
Bug: 169271059
Bug: 169271062
Bug: 170503758
Test: manual test using SF backdoor
diff --git a/services/surfaceflinger/Scheduler/EventThread.cpp b/services/surfaceflinger/Scheduler/EventThread.cpp
index bf5be47..b63e8c8 100644
--- a/services/surfaceflinger/Scheduler/EventThread.cpp
+++ b/services/surfaceflinger/Scheduler/EventThread.cpp
@@ -45,6 +45,9 @@
 #include "FrameTimeline.h"
 #include "HwcStrongTypes.h"
 
+#undef LOG_TAG
+#define LOG_TAG "EventThread"
+
 using namespace std::chrono_literals;
 
 namespace android {
@@ -123,14 +126,36 @@
     return event;
 }
 
+DisplayEventReceiver::Event makeFrameRateOverrideEvent(PhysicalDisplayId displayId,
+                                                       FrameRateOverride frameRateOverride) {
+    return DisplayEventReceiver::Event{
+            .header =
+                    DisplayEventReceiver::Event::Header{
+                            .type = DisplayEventReceiver::DISPLAY_EVENT_FRAME_RATE_OVERRIDE,
+                            .displayId = displayId,
+                            .timestamp = systemTime(),
+                    },
+            .frameRateOverride = frameRateOverride,
+    };
+}
+
+DisplayEventReceiver::Event makeFrameRateOverrideFlushEvent(PhysicalDisplayId displayId) {
+    return DisplayEventReceiver::Event{
+            .header = DisplayEventReceiver::Event::Header{
+                    .type = DisplayEventReceiver::DISPLAY_EVENT_FRAME_RATE_OVERRIDE_FLUSH,
+                    .displayId = displayId,
+                    .timestamp = systemTime(),
+            }};
+}
+
 } // namespace
 
-EventThreadConnection::EventThreadConnection(EventThread* eventThread, uid_t callingUid,
-                                             ResyncCallback resyncCallback,
-                                             ISurfaceComposer::ConfigChanged configChanged)
+EventThreadConnection::EventThreadConnection(
+        EventThread* eventThread, uid_t callingUid, ResyncCallback resyncCallback,
+        ISurfaceComposer::EventRegistrationFlags eventRegistration)
       : resyncCallback(std::move(resyncCallback)),
-        mConfigChanged(configChanged),
         mOwnerUid(callingUid),
+        mEventRegistration(eventRegistration),
         mEventThread(eventThread),
         mChannel(gui::BitTube::DefaultSize) {}
 
@@ -161,8 +186,25 @@
 }
 
 status_t EventThreadConnection::postEvent(const DisplayEventReceiver::Event& event) {
-    ssize_t size = DisplayEventReceiver::sendEvents(&mChannel, &event, 1);
-    return size < 0 ? status_t(size) : status_t(NO_ERROR);
+    constexpr auto toStatus = [](ssize_t size) {
+        return size < 0 ? status_t(size) : status_t(NO_ERROR);
+    };
+
+    if (event.header.type == DisplayEventReceiver::DISPLAY_EVENT_FRAME_RATE_OVERRIDE ||
+        event.header.type == DisplayEventReceiver::DISPLAY_EVENT_FRAME_RATE_OVERRIDE_FLUSH) {
+        mPendingEvents.emplace_back(event);
+        if (event.header.type == DisplayEventReceiver::DISPLAY_EVENT_FRAME_RATE_OVERRIDE) {
+            return status_t(NO_ERROR);
+        }
+
+        auto size = DisplayEventReceiver::sendEvents(&mChannel, mPendingEvents.data(),
+                                                     mPendingEvents.size());
+        mPendingEvents.clear();
+        return toStatus(size);
+    }
+
+    auto size = DisplayEventReceiver::sendEvents(&mChannel, &event, 1);
+    return toStatus(size);
 }
 
 // ---------------------------------------------------------------------------
@@ -220,10 +262,11 @@
 }
 
 sp<EventThreadConnection> EventThread::createEventConnection(
-        ResyncCallback resyncCallback, ISurfaceComposer::ConfigChanged configChanged) const {
+        ResyncCallback resyncCallback,
+        ISurfaceComposer::EventRegistrationFlags eventRegistration) const {
     return new EventThreadConnection(const_cast<EventThread*>(this),
                                      IPCThreadState::self()->getCallingUid(),
-                                     std::move(resyncCallback), configChanged);
+                                     std::move(resyncCallback), eventRegistration);
 }
 
 status_t EventThread::registerDisplayEventConnection(const sp<EventThreadConnection>& connection) {
@@ -333,6 +376,18 @@
     mCondition.notify_all();
 }
 
+void EventThread::onFrameRateOverridesChanged(PhysicalDisplayId displayId,
+                                              std::vector<FrameRateOverride> overrides) {
+    std::lock_guard<std::mutex> lock(mMutex);
+
+    for (auto frameRateOverride : overrides) {
+        mPendingEvents.push_back(makeFrameRateOverrideEvent(displayId, frameRateOverride));
+    }
+    mPendingEvents.push_back(makeFrameRateOverrideFlushEvent(displayId));
+
+    mCondition.notify_all();
+}
+
 size_t EventThread::getEventThreadConnectionCount() {
     std::lock_guard<std::mutex> lock(mMutex);
     return mDisplayEventConnections.size();
@@ -459,7 +514,8 @@
             return true;
 
         case DisplayEventReceiver::DISPLAY_EVENT_CONFIG_CHANGED: {
-            return connection->mConfigChanged == ISurfaceComposer::eConfigChangedDispatch;
+            return connection->mEventRegistration.test(
+                    ISurfaceComposer::EventRegistration::configChanged);
         }
 
         case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
@@ -488,6 +544,12 @@
                     return event.vsync.count % vsyncPeriod(connection->vsyncRequest) == 0;
             }
 
+        case DisplayEventReceiver::DISPLAY_EVENT_FRAME_RATE_OVERRIDE:
+            [[fallthrough]];
+        case DisplayEventReceiver::DISPLAY_EVENT_FRAME_RATE_OVERRIDE_FLUSH:
+            return connection->mEventRegistration.test(
+                    ISurfaceComposer::EventRegistration::frameRateOverride);
+
         default:
             return false;
     }
diff --git a/services/surfaceflinger/Scheduler/EventThread.h b/services/surfaceflinger/Scheduler/EventThread.h
index 2e2d989..e75b718 100644
--- a/services/surfaceflinger/Scheduler/EventThread.h
+++ b/services/surfaceflinger/Scheduler/EventThread.h
@@ -48,6 +48,7 @@
 // ---------------------------------------------------------------------------
 
 using ResyncCallback = std::function<void()>;
+using FrameRateOverride = DisplayEventReceiver::Event::FrameRateOverride;
 
 enum class VSyncRequest {
     None = -2,
@@ -82,7 +83,7 @@
 class EventThreadConnection : public BnDisplayEventConnection {
 public:
     EventThreadConnection(EventThread*, uid_t callingUid, ResyncCallback,
-                          ISurfaceComposer::ConfigChanged configChanged);
+                          ISurfaceComposer::EventRegistrationFlags eventRegistration = {});
     virtual ~EventThreadConnection();
 
     virtual status_t postEvent(const DisplayEventReceiver::Event& event);
@@ -95,15 +96,15 @@
     const ResyncCallback resyncCallback;
 
     VSyncRequest vsyncRequest = VSyncRequest::None;
-    const ISurfaceComposer::ConfigChanged mConfigChanged =
-            ISurfaceComposer::ConfigChanged::eConfigChangedSuppress;
-
     const uid_t mOwnerUid;
+    const ISurfaceComposer::EventRegistrationFlags mEventRegistration;
 
 private:
     virtual void onFirstRef();
     EventThread* const mEventThread;
     gui::BitTube mChannel;
+
+    std::vector<DisplayEventReceiver::Event> mPendingEvents;
 };
 
 class EventThread {
@@ -111,7 +112,8 @@
     virtual ~EventThread();
 
     virtual sp<EventThreadConnection> createEventConnection(
-            ResyncCallback, ISurfaceComposer::ConfigChanged configChanged) const = 0;
+            ResyncCallback,
+            ISurfaceComposer::EventRegistrationFlags eventRegistration = {}) const = 0;
 
     // called before the screen is turned off from main thread
     virtual void onScreenReleased() = 0;
@@ -125,6 +127,10 @@
     virtual void onConfigChanged(PhysicalDisplayId displayId, HwcConfigIndexType configId,
                                  nsecs_t vsyncPeriod) = 0;
 
+    // called when SF updates the Frame Rate Override list
+    virtual void onFrameRateOverridesChanged(PhysicalDisplayId displayId,
+                                             std::vector<FrameRateOverride> overrides) = 0;
+
     virtual void dump(std::string& result) const = 0;
 
     virtual void setDuration(std::chrono::nanoseconds workDuration,
@@ -152,7 +158,8 @@
     ~EventThread();
 
     sp<EventThreadConnection> createEventConnection(
-            ResyncCallback, ISurfaceComposer::ConfigChanged configChanged) const override;
+            ResyncCallback,
+            ISurfaceComposer::EventRegistrationFlags eventRegistration = {}) const override;
 
     status_t registerDisplayEventConnection(const sp<EventThreadConnection>& connection) override;
     void setVsyncRate(uint32_t rate, const sp<EventThreadConnection>& connection) override;
@@ -169,6 +176,9 @@
     void onConfigChanged(PhysicalDisplayId displayId, HwcConfigIndexType configId,
                          nsecs_t vsyncPeriod) override;
 
+    void onFrameRateOverridesChanged(PhysicalDisplayId displayId,
+                                     std::vector<FrameRateOverride> overrides) override;
+
     void dump(std::string& result) const override;
 
     void setDuration(std::chrono::nanoseconds workDuration,
diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp b/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp
index b872d7a..8b4283c 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.cpp
@@ -687,21 +687,20 @@
     return RefreshRateConfigs::KernelIdleTimerAction::TurnOn;
 }
 
-void RefreshRateConfigs::setPreferredRefreshRateForUid(uid_t uid, float refreshRateHz) {
-    if (refreshRateHz > 0 && refreshRateHz < 1) {
+void RefreshRateConfigs::setPreferredRefreshRateForUid(FrameRateOverride frameRateOverride) {
+    if (frameRateOverride.frameRateHz > 0 && frameRateOverride.frameRateHz < 1) {
         return;
     }
 
     std::lock_guard lock(mLock);
-    if (refreshRateHz != 0) {
-        mPreferredRefreshRateForUid[uid] = refreshRateHz;
+    if (frameRateOverride.frameRateHz != 0) {
+        mPreferredRefreshRateForUid[frameRateOverride.uid] = frameRateOverride.frameRateHz;
     } else {
-        mPreferredRefreshRateForUid.erase(uid);
+        mPreferredRefreshRateForUid.erase(frameRateOverride.uid);
     }
 }
 
 int RefreshRateConfigs::getRefreshRateDividerForUid(uid_t uid) const {
-    constexpr float kThreshold = 0.1f;
     std::lock_guard lock(mLock);
 
     const auto iter = mPreferredRefreshRateForUid.find(uid);
@@ -709,6 +708,9 @@
         return 1;
     }
 
+    // This calculation needs to be in sync with the java code
+    // in DisplayManagerService.getDisplayInfoForFrameRateOverride
+    constexpr float kThreshold = 0.1f;
     const auto refreshRateHz = iter->second;
     const auto numPeriods = mCurrentRefreshRate->getFps() / refreshRateHz;
     const auto numPeriodsRounded = std::round(numPeriods);
@@ -716,7 +718,19 @@
         return 1;
     }
 
-    return static_cast<int>(numPeriods);
+    return static_cast<int>(numPeriodsRounded);
+}
+
+std::vector<FrameRateOverride> RefreshRateConfigs::getFrameRateOverrides() {
+    std::lock_guard lock(mLock);
+    std::vector<FrameRateOverride> overrides;
+    overrides.reserve(mPreferredRefreshRateForUid.size());
+
+    for (const auto [uid, frameRate] : mPreferredRefreshRateForUid) {
+        overrides.emplace_back(FrameRateOverride{uid, frameRate});
+    }
+
+    return overrides;
 }
 
 void RefreshRateConfigs::dump(std::string& result) const {
diff --git a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
index 3159352..a873777 100644
--- a/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
+++ b/services/surfaceflinger/Scheduler/RefreshRateConfigs.h
@@ -17,6 +17,7 @@
 #pragma once
 
 #include <android-base/stringprintf.h>
+#include <gui/DisplayEventReceiver.h>
 
 #include <algorithm>
 #include <numeric>
@@ -39,6 +40,8 @@
     return static_cast<RefreshRateConfigEvent>(static_cast<T>(lhs) | static_cast<T>(rhs));
 }
 
+using FrameRateOverride = DisplayEventReceiver::Event::FrameRateOverride;
+
 /**
  * This class is used to encapsulate configuration for refresh rates. It holds information
  * about available refresh rates on the device, and the mapping between the numbers and human
@@ -316,14 +319,17 @@
     KernelIdleTimerAction getIdleTimerAction() const;
 
     // Stores the preferred refresh rate that an app should run at.
-    // refreshRate == 0 means no preference.
-    void setPreferredRefreshRateForUid(uid_t, float refreshRateHz) EXCLUDES(mLock);
+    // FrameRateOverride.refreshRateHz == 0 means no preference.
+    void setPreferredRefreshRateForUid(FrameRateOverride) EXCLUDES(mLock);
 
     // Returns a divider for the current refresh rate
     int getRefreshRateDividerForUid(uid_t) const EXCLUDES(mLock);
 
     void dump(std::string& result) const EXCLUDES(mLock);
 
+    // Returns the current frame rate overrides
+    std::vector<FrameRateOverride> getFrameRateOverrides() EXCLUDES(mLock);
+
 private:
     friend class RefreshRateConfigsTest;
 
@@ -381,6 +387,8 @@
     Policy mDisplayManagerPolicy GUARDED_BY(mLock);
     std::optional<Policy> mOverridePolicy GUARDED_BY(mLock);
 
+    // A mapping between a UID and a preferred refresh rate that this app would
+    // run at.
     std::unordered_map<uid_t, float> mPreferredRefreshRateForUid GUARDED_BY(mLock);
 
     // The min and max refresh rates supported by the device.
diff --git a/services/surfaceflinger/Scheduler/Scheduler.cpp b/services/surfaceflinger/Scheduler/Scheduler.cpp
index a14019e..a93bf11 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.cpp
+++ b/services/surfaceflinger/Scheduler/Scheduler.cpp
@@ -239,8 +239,7 @@
     const ConnectionHandle handle = ConnectionHandle{mNextConnectionHandleId++};
     ALOGV("Creating a connection handle with ID %" PRIuPTR, handle.id);
 
-    auto connection =
-            createConnectionInternal(eventThread.get(), ISurfaceComposer::eConfigChangedSuppress);
+    auto connection = createConnectionInternal(eventThread.get());
 
     std::lock_guard<std::mutex> lock(mConnectionsLock);
     mConnections.emplace(handle, Connection{connection, std::move(eventThread)});
@@ -248,15 +247,15 @@
 }
 
 sp<EventThreadConnection> Scheduler::createConnectionInternal(
-        EventThread* eventThread, ISurfaceComposer::ConfigChanged configChanged) {
-    return eventThread->createEventConnection([&] { resync(); }, configChanged);
+        EventThread* eventThread, ISurfaceComposer::EventRegistrationFlags eventRegistration) {
+    return eventThread->createEventConnection([&] { resync(); }, eventRegistration);
 }
 
 sp<IDisplayEventConnection> Scheduler::createDisplayEventConnection(
-        ConnectionHandle handle, ISurfaceComposer::ConfigChanged configChanged) {
+        ConnectionHandle handle, ISurfaceComposer::EventRegistrationFlags eventRegistration) {
     std::lock_guard<std::mutex> lock(mConnectionsLock);
     RETURN_IF_INVALID_HANDLE(handle, nullptr);
-    return createConnectionInternal(mConnections[handle].thread.get(), configChanged);
+    return createConnectionInternal(mConnections[handle].thread.get(), eventRegistration);
 }
 
 sp<EventThreadConnection> Scheduler::getEventConnection(ConnectionHandle handle) {
@@ -297,6 +296,17 @@
     thread->onScreenReleased();
 }
 
+void Scheduler::onFrameRateOverridesChanged(ConnectionHandle handle, PhysicalDisplayId displayId,
+                                            std::vector<FrameRateOverride> overrides) {
+    android::EventThread* thread;
+    {
+        std::lock_guard<std::mutex> lock(mConnectionsLock);
+        RETURN_IF_INVALID_HANDLE(handle);
+        thread = mConnections[handle].thread.get();
+    }
+    thread->onFrameRateOverridesChanged(displayId, std::move(overrides));
+}
+
 void Scheduler::onPrimaryDisplayConfigChanged(ConnectionHandle handle, PhysicalDisplayId displayId,
                                               HwcConfigIndexType configId, nsecs_t vsyncPeriod) {
     std::lock_guard<std::mutex> lock(mFeatureStateLock);
diff --git a/services/surfaceflinger/Scheduler/Scheduler.h b/services/surfaceflinger/Scheduler/Scheduler.h
index 4c86d26..76e8f57 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.h
+++ b/services/surfaceflinger/Scheduler/Scheduler.h
@@ -79,8 +79,8 @@
                                       std::chrono::nanoseconds readyDuration,
                                       impl::EventThread::InterceptVSyncsCallback);
 
-    sp<IDisplayEventConnection> createDisplayEventConnection(ConnectionHandle,
-                                                             ISurfaceComposer::ConfigChanged);
+    sp<IDisplayEventConnection> createDisplayEventConnection(
+            ConnectionHandle, ISurfaceComposer::EventRegistrationFlags eventRegistration = {});
 
     sp<EventThreadConnection> getEventConnection(ConnectionHandle);
 
@@ -93,6 +93,9 @@
     void onScreenAcquired(ConnectionHandle);
     void onScreenReleased(ConnectionHandle);
 
+    void onFrameRateOverridesChanged(ConnectionHandle, PhysicalDisplayId,
+                                     std::vector<FrameRateOverride>);
+
     // Modifies work duration in the event thread.
     void setDuration(ConnectionHandle, std::chrono::nanoseconds workDuration,
                      std::chrono::nanoseconds readyDuration);
@@ -203,8 +206,8 @@
 
     // Create a connection on the given EventThread.
     ConnectionHandle createConnection(std::unique_ptr<EventThread>);
-    sp<EventThreadConnection> createConnectionInternal(EventThread*,
-                                                       ISurfaceComposer::ConfigChanged);
+    sp<EventThreadConnection> createConnectionInternal(
+            EventThread*, ISurfaceComposer::EventRegistrationFlags eventRegistration = {});
 
     // Update feature state machine to given state when corresponding timer resets or expires.
     void kernelIdleTimerCallback(TimerState);