ThemedResourceCache: Replace ArrayMap with HashMap for performance

When opening and closing activities in Settings, a significant amount of
CPU time is spent looking up ArrayMap entries, as reported by simpleperf:

0.12%     /system/framework/arm64/boot-framework.oat                                                                                                android.util.ArrayMap.binarySearchHashes

ThemedResourceCache is responsible for a significant portion of the time
spent in ArrayMap lookups:

0.08%     0.08%  /system/framework/arm64/boot-framework.oat                                                                              android.util.ArrayMap.binarySearchHashes
       |
       -- android.util.ArrayMap.binarySearchHashes
          |
           --50.00%-- android.util.ArrayMap.indexOf
               |
               |--36.71%-- android.util.ArrayMap.get
               |    |--0.87%-- [hit in function]
               |    |
               |    |--9.64%-- android.content.res.ThemedResourceCache.getThemedLocked
               |    |          android.content.res.ThemedResourceCache.get
               |    |    |
               |    |    |--77.92%-- android.content.res.DrawableCache.getInstance
               |    |    |           android.content.res.ResourcesImpl.loadDrawable
               |    |    |           android.content.res.Resources.loadDrawable
               |    |    |           android.content.res.TypedArray.getDrawableForDensity
               |    |    |           android.content.res.Resources.getColor [DEDUPED]
               |    |    |    |
               |    |    |    |--62.94%-- android.view.View.<init>
               |    |    |    |    |
               |    |    |    |    |--64.58%-- android.view.ViewGroup.<init>
               |    |    |    |    |           android.widget.LinearLayout.<init>
               |    |    |    |    |           android.widget.LinearLayout.<init>
               |    |    |    |    |           art_quick_invoke_stub
               |    |    |    |    |           art::ArtMethod::Invoke(art::Thread*, unsigned int*, unsigned int, art::JValue*, char const*)
               |    |    |    |    |           art::InvokeConstructor(art::ScopedObjectAccessAlreadyRunnable const&, art::ArtMethod*, art::ObjPtr<art::mirror::Object>, _jobject*)
               |    |    |    |    |           art::Constructor_newInstance0(_JNIEnv*, _jobject*, _jobjectArray*)
               |    |    |    |    |           art_jni_trampoline
               |    |    |    |    |           java.lang.reflect.Constructor.newInstance
               |    |    |    |    |           android.view.LayoutInflater.createView
               |    |    |    |    |           com.android.internal.policy.PhoneLayoutInflater.onCreateView
               |    |    |    |    |           android.view.LayoutInflater.onCreateView
               |    |    |    |    |           android.view.LayoutInflater.onCreateView
               |    |    |    |    |           android.view.LayoutInflater.createViewFromTag
               |    |    |    |    |           android.view.LayoutInflater.inflate
               |    |    |    |    |           android.view.LayoutInflater.inflate
               |    |    |    |    |
               |    |    |    |     --35.42%-- android.widget.TextView.<init>
               |    |    |    |                android.widget.Button.<init>
               |    |    |    |                art_quick_invoke_stub
               |    |    |    |                art::ArtMethod::Invoke(art::Thread*, unsigned int*, unsigned int, art::JValue*, char const*)
               |    |    |    |                art::InvokeConstructor(art::ScopedObjectAccessAlreadyRunnable const&, art::ArtMethod*, art::ObjPtr<art::mirror::Object>, _jobject*)
               |    |    |    |                art::Constructor_newInstance0(_JNIEnv*, _jobject*, _jobjectArray*)
               |    |    |    |                art_jni_trampoline
               |    |    |    |                java.lang.reflect.Constructor.newInstance
               |    |    |    |                android.view.LayoutInflater.createView
               |    |    |    |                com.android.internal.policy.PhoneLayoutInflater.onCreateView
               |    |    |    |                android.view.LayoutInflater.onCreateView
               |    |    |    |                android.view.LayoutInflater.onCreateView
               |    |    |    |                android.view.LayoutInflater.createViewFromTag
               |    |    |    |                android.view.LayoutInflater.rInflate
               |    |    |    |                android.view.LayoutInflater.rInflate
               |    |    |    |                android.view.LayoutInflater.rInflate
               |    |    |    |                android.view.LayoutInflater.inflate
               |    |    |    |                android.view.LayoutInflater.inflate
               |    |    |    |                android.view.LayoutInflater.inflate
               |    |    |    |
               |    |    |     --37.06%-- com.android.internal.widget.ToolbarWidgetWrapper.<init>
               |    |    |
               |    |     --22.08%-- android.content.res.ConfigurationBoundResourceCache.get
               |    |                android.content.res.ConfigurationBoundResourceCache.getInstance
               |    |                android.content.res.ResourcesImpl.loadComplexColorFromName
               |    |                android.content.res.ResourcesImpl.loadColorStateList
               |    |                android.content.res.Resources.loadColorStateList
               |    |                android.content.res.TypedArray.getColorStateList
               |    |                android.widget.TextView.readTextAppearance
               |    |                android.widget.TextView.setTextAppearance
               |    |                android.widget.TextView.setTextAppearance
               |    |                android.widget.Toolbar.setTitle
               |    |                com.android.wifi.x.com.android.internal.util.StateMachine$SmHandler.handleMessage
               |    |                android.view.SurfaceControl.copyFrom

Empirical testing reveals that mThemedEntries usually contains around 14
entries, at which HashMap is 35% faster than ArrayMap for lookups and
54% faster [1] for insertions. The increased memory usage should be
negligible at this size, so we can safely convert the map to a HashMap
in order to improve performance in this hotpath.

[1] https://docs.google.com/spreadsheets/d/136UJS2yVlZyPx30KDNgj4AWldkp9xbzIcWkLFj9RGgk/edit

Test: simpleperf record -a; verify that ThemedResourceCache no longer
      appears under ArrayMap.binarySearchHashes
Change-Id: I39e1c4b03fe0e60f933f02e253d2d3c4a483146f

1 files changed, 5 insertions, 8 deletions

diff --git a/core/java/android/content/res/ThemedResourceCache.java b/core/java/android/content/res/ThemedResourceCache.java
index 3270944ce7e3..e0701b90d6fa 100644
--- a/core/java/android/content/res/ThemedResourceCache.java
+++ b/core/java/android/content/res/ThemedResourceCache.java
@@ -22,10 +22,10 @@ import android.compat.annotation.UnsupportedAppUsage;
 import android.content.pm.ActivityInfo.Config;
 import android.content.res.Resources.Theme;
 import android.content.res.Resources.ThemeKey;
-import android.util.ArrayMap;
 import android.util.LongSparseArray;
 
 import java.lang.ref.WeakReference;
+import java.util.HashMap;
 
 /**
  * Data structure used for caching data against themes.
@@ -34,7 +34,7 @@ import java.lang.ref.WeakReference;
  */
 abstract class ThemedResourceCache<T> {
     @UnsupportedAppUsage
-    private ArrayMap<ThemeKey, LongSparseArray<WeakReference<T>>> mThemedEntries;
+    private HashMap<ThemeKey, LongSparseArray<WeakReference<T>>> mThemedEntries;
     private LongSparseArray<WeakReference<T>> mUnthemedEntries;
     private LongSparseArray<WeakReference<T>> mNullThemedEntries;
 
@@ -154,7 +154,7 @@ abstract class ThemedResourceCache<T> {
 
         if (mThemedEntries == null) {
             if (create) {
-                mThemedEntries = new ArrayMap<>(1);
+                mThemedEntries = new HashMap<>(1);
             } else {
                 return null;
             }
@@ -199,11 +199,8 @@ abstract class ThemedResourceCache<T> {
     private boolean prune(@Config int configChanges) {
         synchronized (this) {
             if (mThemedEntries != null) {
-                for (int i = mThemedEntries.size() - 1; i >= 0; i--) {
-                    if (pruneEntriesLocked(mThemedEntries.valueAt(i), configChanges)) {
-                        mThemedEntries.removeAt(i);
-                    }
-                }
+                mThemedEntries.entrySet()
+                    .removeIf(entry -> pruneEntriesLocked(entry.getValue(), configChanges));
             }
 
             pruneEntriesLocked(mNullThemedEntries, configChanges);