Fix lock contention in ResourcesManager
1. Scope dowm synchronized block to mAdjustedDisplays put and get
2. Use SoftReference instead of WeakReference because
display's weak reference is cleared after getAdjustedDisplay
returned and the cache didn't take effects previously.
fixes: 162445376
Test: ResourcesManagerPerfTest
Before:
getDisplayMetrics_median: 3413
getDisplayMetrics_mean: 3439
getDisplayMetrics_min: 3364
getDisplayMetrics_standardDeviation: 107
After:
getDisplayMetrics_median: 3048
getDisplayMetrics_mean: 3096
getDisplayMetrics_min: 2999
getDisplayMetrics_standardDeviation: 134
Change-Id: I8a5c3ba960c8231aee78b0e7fb958bf6845d5bb5
diff --git a/apct-tests/perftests/core/src/android/app/ResourcesManagerPerfTest.java b/apct-tests/perftests/core/src/android/app/ResourcesManagerPerfTest.java
index 050fecd..d3938f4 100644
--- a/apct-tests/perftests/core/src/android/app/ResourcesManagerPerfTest.java
+++ b/apct-tests/perftests/core/src/android/app/ResourcesManagerPerfTest.java
@@ -17,7 +17,6 @@
import android.content.Context;
import android.content.res.Configuration;
-import android.content.res.Resources;
import android.perftests.utils.BenchmarkState;
import android.perftests.utils.PerfStatusReporter;
import android.view.Display;
@@ -136,4 +135,22 @@
}
}
}
+
+ @Test
+ public void getDisplayMetrics() {
+ ResourcesManager resourcesManager = ResourcesManager.getInstance();
+
+ final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();
+ while (state.keepRunning()) {
+ state.pauseTiming();
+ // Invalidate cache.
+ resourcesManager.applyConfigurationToResourcesLocked(
+ resourcesManager.getConfiguration(), null);
+ state.resumeTiming();
+
+ // Invoke twice for testing cache.
+ resourcesManager.getDisplayMetrics();
+ resourcesManager.getDisplayMetrics();
+ }
+ }
}
diff --git a/core/java/android/app/ResourcesManager.java b/core/java/android/app/ResourcesManager.java
index 7cd3fca..9e4ab33 100644
--- a/core/java/android/app/ResourcesManager.java
+++ b/core/java/android/app/ResourcesManager.java
@@ -54,6 +54,7 @@
import java.io.PrintWriter;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
+import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Arrays;
@@ -245,7 +246,7 @@
/**
* A cache of DisplayId, DisplayAdjustments to Display.
*/
- private final ArrayMap<Pair<Integer, DisplayAdjustments>, WeakReference<Display>>
+ private final ArrayMap<Pair<Integer, DisplayAdjustments>, SoftReference<Display>>
mAdjustedDisplays = new ArrayMap<>();
/**
@@ -373,25 +374,28 @@
? new DisplayAdjustments(displayAdjustments) : new DisplayAdjustments();
final Pair<Integer, DisplayAdjustments> key =
Pair.create(displayId, displayAdjustmentsCopy);
+ SoftReference<Display> sd;
synchronized (this) {
- WeakReference<Display> wd = mAdjustedDisplays.get(key);
- if (wd != null) {
- final Display display = wd.get();
- if (display != null) {
- return display;
- }
- }
- final DisplayManagerGlobal dm = DisplayManagerGlobal.getInstance();
- if (dm == null) {
- // may be null early in system startup
- return null;
- }
- final Display display = dm.getCompatibleDisplay(displayId, key.second);
- if (display != null) {
- mAdjustedDisplays.put(key, new WeakReference<>(display));
- }
- return display;
+ sd = mAdjustedDisplays.get(key);
}
+ if (sd != null) {
+ final Display display = sd.get();
+ if (display != null) {
+ return display;
+ }
+ }
+ final DisplayManagerGlobal dm = DisplayManagerGlobal.getInstance();
+ if (dm == null) {
+ // may be null early in system startup
+ return null;
+ }
+ final Display display = dm.getCompatibleDisplay(displayId, key.second);
+ if (display != null) {
+ synchronized (this) {
+ mAdjustedDisplays.put(key, new SoftReference<>(display));
+ }
+ }
+ return display;
}
/**
