From b5e1153d03dc5e830519a21224f308248450fae4 Mon Sep 17 00:00:00 2001
From: Tim Murray <timmurray@google.com>
Date: Tue, 12 Nov 2019 18:23:50 -0800
Subject: LocationManager: cache isLocationEnabledForUser

This method is in the hot path for all location tasks but whether
location is enabled for a particular user doesn't change that
often. Cache the result and invalidate from system_server in order to
reduce CPU consumption.

Test: boots, works, gets location
Bug: 140788621

Change-Id: I84ad2c570e7024187a728071dcbb6f72b177e17a
---
 .../java/android/location/LocationManager.java     | 48 ++++++++++++++++++++++
 1 file changed, 48 insertions(+)

(limited to 'location')

diff --git a/location/java/android/location/LocationManager.java b/location/java/android/location/LocationManager.java
index 19085bff0033..6028a8a90141 100644
--- a/location/java/android/location/LocationManager.java
+++ b/location/java/android/location/LocationManager.java
@@ -35,6 +35,7 @@ import android.annotation.SystemService;
 import android.annotation.TestApi;
 import android.app.AlarmManager;
 import android.app.PendingIntent;
+import android.app.PropertyInvalidatedCache;
 import android.compat.Compatibility;
 import android.compat.annotation.ChangeId;
 import android.compat.annotation.EnabledAfter;
@@ -84,6 +85,23 @@ import java.util.function.Consumer;
 @RequiresFeature(PackageManager.FEATURE_LOCATION)
 public class LocationManager {
 
+    @GuardedBy("mLock")
+    private PropertyInvalidatedCache<Integer, Boolean> mLocationEnabledCache =
+            new PropertyInvalidatedCache<Integer, Boolean>(
+                4,
+                CACHE_KEY_LOCATION_ENABLED_PROPERTY) {
+                @Override
+                protected Boolean recompute(Integer userHandle) {
+                    try {
+                        return mService.isLocationEnabledForUser(userHandle);
+                    } catch (RemoteException e) {
+                        throw e.rethrowFromSystemServer();
+                    }
+                }
+            };
+
+    private final Object mLock = new Object();
+
     /**
      * For apps targeting Android K and above, supplied {@link PendingIntent}s must be targeted to a
      * specific package.
@@ -462,6 +480,13 @@ public class LocationManager {
      */
     @SystemApi
     public boolean isLocationEnabledForUser(@NonNull UserHandle userHandle) {
+        synchronized (mLock) {
+            if (mLocationEnabledCache != null) {
+                return mLocationEnabledCache.query(userHandle.getIdentifier());
+            }
+        }
+
+        // fallback if cache is disabled
         try {
             return mService.isLocationEnabledForUser(userHandle.getIdentifier());
         } catch (RemoteException e) {
@@ -3107,6 +3132,29 @@ public class LocationManager {
             public void onLocationBatch(List<Location> locations) {
                 execute((listener) -> listener.onLocationBatch(locations));
             }
+
+        }
+    }
+
+    /**
+     * @hide
+     */
+    public static final String CACHE_KEY_LOCATION_ENABLED_PROPERTY =
+            "cache_key.location_enabled";
+
+    /**
+     * @hide
+     */
+    public static void invalidateLocalLocationEnabledCaches() {
+        PropertyInvalidatedCache.invalidateCache(CACHE_KEY_LOCATION_ENABLED_PROPERTY);
+    }
+
+    /**
+     * @hide
+     */
+    public void disableLocalLocationEnabledCaches() {
+        synchronized (mLock) {
+            mLocationEnabledCache = null;
         }
     }
 }
-- 
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