commit 60aee1c46b52852e140f05748f69e38f4e3de36e
author Alec Mouri <alecmouri@google.com> Mon Oct 28 16:18:59 2019 -0700
committer Alec Mouri <alecmouri@google.com> Thu Dec 26 10:28:47 2019 -0800
tree 7a29657039f1f8911fdef5689aa39e7fd4f3f6bd
parent 516de508aa52a0907a496890dc191501481bca7b

[AChoreographer] Add refresh rate callback.

This will augment the NDK to respond to display events where the display
refresh rate changes. Consumers of this api will include:
* HWUI, for implementing a policy for determining whether to use
render-ahead,
* Swappy, to potentially replace jumping into Java from native code to
respond to display evnets there.
* Any other native app that would rely on the up-to-date display refresh
rate.

Currently however this is not yet exposed to NDK as CTS is not yet
written. Once CTS is written then this will be formally exposed to NDK.
For now we'll leave these as APEX apis to represent incremental
progress.

Bug: 136262896
Test: builds
Change-Id: I66d393f93eb5d681547411e330ef1b8950a35c5d

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index fed2395..6e827ac 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -956,8 +956,11 @@
     ATRACE_INT("ActiveConfigFPS", refreshRate.fps);
 
     if (mUpcomingActiveConfig.event != Scheduler::ConfigEvent::None) {
+        const nsecs_t vsyncPeriod =
+                mRefreshRateConfigs->getRefreshRateFromConfigId(mUpcomingActiveConfig.configId)
+                        .vsyncPeriod;
         mScheduler->onConfigChanged(mAppConnectionHandle, display->getId()->value,
-                                    mUpcomingActiveConfig.configId);
+                                    mUpcomingActiveConfig.configId, vsyncPeriod);
     }
 }
 
@@ -2614,6 +2617,17 @@
     mRegionSamplingThread =
             new RegionSamplingThread(*this, *mScheduler,
                                      RegionSamplingThread::EnvironmentTimingTunables());
+    // Dispatch a config change request for the primary display on scheduler
+    // initialization, so that the EventThreads always contain a reference to a
+    // prior configuration.
+    //
+    // This is a bit hacky, but this avoids a back-pointer into the main SF
+    // classes from EventThread, and there should be no run-time binder cost
+    // anyway since there are no connected apps at this point.
+    const nsecs_t vsyncPeriod =
+            mRefreshRateConfigs->getRefreshRateFromConfigId(currentConfig).vsyncPeriod;
+    mScheduler->onConfigChanged(mAppConnectionHandle, primaryDisplayId.value, currentConfig,
+                                vsyncPeriod);
 }
 
 void SurfaceFlinger::commitTransaction()
@@ -5499,7 +5513,10 @@
 
         auto configId = HwcConfigIndexType(defaultConfig);
         display->setActiveConfig(configId);
-        mScheduler->onConfigChanged(mAppConnectionHandle, display->getId()->value, configId);
+        const nsecs_t vsyncPeriod =
+                mRefreshRateConfigs->getRefreshRateFromConfigId(configId).vsyncPeriod;
+        mScheduler->onConfigChanged(mAppConnectionHandle, display->getId()->value, configId,
+                                    vsyncPeriod);
         return NO_ERROR;
     }
 
@@ -5523,8 +5540,10 @@
     // TODO(b/140204874): This hack triggers a notification that something has changed, so
     // that listeners that care about a change in allowed configs can get the notification.
     // Giving current ActiveConfig so that most other listeners would just drop the event
+    const nsecs_t vsyncPeriod =
+            mRefreshRateConfigs->getRefreshRateFromConfigId(display->getActiveConfig()).vsyncPeriod;
     mScheduler->onConfigChanged(mAppConnectionHandle, display->getId()->value,
-                                display->getActiveConfig());
+                                display->getActiveConfig(), vsyncPeriod);
 
     if (mRefreshRateConfigs->refreshRateSwitchingSupported()) {
         auto configId = mScheduler->getPreferredConfigId();