From bc95621811b0c15904a4783aae34e94aa109f764 Mon Sep 17 00:00:00 2001
From: Narayan Kamath <narayan@google.com>
Date: Mon, 13 Aug 2018 12:53:38 +0100
Subject: ResourceManager: Disable APK Assets cache.

The WeakReference based cache of Assets in use elsewhere in the
process remains unchanged.

Note that this change is larger than it needs to be because it is
an error to create an LruCache of size zero.

There seems to be no measurable difference as measured by the standard
app startup benchmarks.

Test: atest -v google/perf/app-startup/benchmark-app-hermetic/cold-dropcache-test
Bug: 111385832
Change-Id: I432c069e90124e884bddc5cd5be43a28e1b16d07
---
 core/java/android/app/ResourcesManager.java | 53 +++++++++++++++++++----------
 1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/core/java/android/app/ResourcesManager.java b/core/java/android/app/ResourcesManager.java
index 30256b42e6a1..f9929712255c 100644
--- a/core/java/android/app/ResourcesManager.java
+++ b/core/java/android/app/ResourcesManager.java
@@ -121,10 +121,13 @@ public class ResourcesManager {
         }
     }
 
+    private static final boolean ENABLE_APK_ASSETS_CACHE = true;
+
     /**
      * The ApkAssets we are caching and intend to hold strong references to.
      */
-    private final LruCache<ApkKey, ApkAssets> mLoadedApkAssets = new LruCache<>(3);
+    private final LruCache<ApkKey, ApkAssets> mLoadedApkAssets =
+            (ENABLE_APK_ASSETS_CACHE) ? new LruCache<>(3) : null;
 
     /**
      * The ApkAssets that are being referenced in the wild that we can reuse, even if they aren't
@@ -310,9 +313,12 @@ public class ResourcesManager {
     private @NonNull ApkAssets loadApkAssets(String path, boolean sharedLib, boolean overlay)
             throws IOException {
         final ApkKey newKey = new ApkKey(path, sharedLib, overlay);
-        ApkAssets apkAssets = mLoadedApkAssets.get(newKey);
-        if (apkAssets != null) {
-            return apkAssets;
+        ApkAssets apkAssets = null;
+        if (mLoadedApkAssets != null) {
+            apkAssets = mLoadedApkAssets.get(newKey);
+            if (apkAssets != null) {
+                return apkAssets;
+            }
         }
 
         // Optimistically check if this ApkAssets exists somewhere else.
@@ -320,7 +326,10 @@ public class ResourcesManager {
         if (apkAssetsRef != null) {
             apkAssets = apkAssetsRef.get();
             if (apkAssets != null) {
-                mLoadedApkAssets.put(newKey, apkAssets);
+                if (mLoadedApkAssets != null) {
+                    mLoadedApkAssets.put(newKey, apkAssets);
+                }
+
                 return apkAssets;
             } else {
                 // Clean up the reference.
@@ -335,7 +344,11 @@ public class ResourcesManager {
         } else {
             apkAssets = ApkAssets.loadFromPath(path, false /*system*/, sharedLib);
         }
-        mLoadedApkAssets.put(newKey, apkAssets);
+
+        if (mLoadedApkAssets != null) {
+            mLoadedApkAssets.put(newKey, apkAssets);
+        }
+
         mCachedApkAssets.put(newKey, new WeakReference<>(apkAssets));
         return apkAssets;
     }
@@ -434,18 +447,22 @@ public class ResourcesManager {
 
             pw.println("ResourcesManager:");
             pw.increaseIndent();
-            pw.print("cached apks: total=");
-            pw.print(mLoadedApkAssets.size());
-            pw.print(" created=");
-            pw.print(mLoadedApkAssets.createCount());
-            pw.print(" evicted=");
-            pw.print(mLoadedApkAssets.evictionCount());
-            pw.print(" hit=");
-            pw.print(mLoadedApkAssets.hitCount());
-            pw.print(" miss=");
-            pw.print(mLoadedApkAssets.missCount());
-            pw.print(" max=");
-            pw.print(mLoadedApkAssets.maxSize());
+            if (mLoadedApkAssets != null) {
+                pw.print("cached apks: total=");
+                pw.print(mLoadedApkAssets.size());
+                pw.print(" created=");
+                pw.print(mLoadedApkAssets.createCount());
+                pw.print(" evicted=");
+                pw.print(mLoadedApkAssets.evictionCount());
+                pw.print(" hit=");
+                pw.print(mLoadedApkAssets.hitCount());
+                pw.print(" miss=");
+                pw.print(mLoadedApkAssets.missCount());
+                pw.print(" max=");
+                pw.print(mLoadedApkAssets.maxSize());
+            } else {
+                pw.print("cached apks: 0 [cache disabled]");
+            }
             pw.println();
 
             pw.print("total apks: ");
-- 
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