From 9202f4dbd37b7672af726899cfa583d10bc0eff8 Mon Sep 17 00:00:00 2001
From: Lee Shombert <shombert@google.com>
Date: Thu, 13 Feb 2020 11:34:40 -0800
Subject: [PATCH] Binder cache for Bluetooth getBondState()

Bug: 140788621

Test: A special build that puts the PropertyInvalidatedCache in verification
mode was loaded on the device.  Then one iteration of MPTS was executed.  No
cache inconsistencies were found and no SELinux violations (associated with
the binder cache) were found.  The number of cache misses was approximately
10% of the total binder calls.  Then the phone was cycled through bluetooth
pairing and unpairing events.

Change-Id: Ia494f0ad58b889130052e5beb3bec6d1011508ef
---
 .../android/bluetooth/BluetoothDevice.java    | 36 +++++++++++++++++--
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/core/java/android/bluetooth/BluetoothDevice.java b/core/java/android/bluetooth/BluetoothDevice.java
index 5b60b85f47218..3e1a480b4f661 100644
--- a/core/java/android/bluetooth/BluetoothDevice.java
+++ b/core/java/android/bluetooth/BluetoothDevice.java
@@ -25,6 +25,7 @@ import android.annotation.SdkConstant;
 import android.annotation.SdkConstant.SdkConstantType;
 import android.annotation.SuppressLint;
 import android.annotation.SystemApi;
+import android.app.PropertyInvalidatedCache;
 import android.compat.annotation.UnsupportedAppUsage;
 import android.content.Context;
 import android.os.Handler;
@@ -1299,6 +1300,31 @@ public final class BluetoothDevice implements Parcelable {
         return false;
     }
 
+    private static final String BLUETOOTH_BONDING_CACHE_PROPERTY =
+            "cache_key.bluetooth.get_bond_state";
+    private final PropertyInvalidatedCache<BluetoothDevice, Integer> mBluetoothBondCache =
+            new PropertyInvalidatedCache<BluetoothDevice, Integer>(
+                8, BLUETOOTH_BONDING_CACHE_PROPERTY) {
+                @Override
+                protected Integer recompute(BluetoothDevice query) {
+                    try {
+                        return sService.getBondState(query);
+                    } catch (RemoteException e) {
+                        throw e.rethrowAsRuntimeException();
+                    }
+                }
+            };
+
+    /** @hide */
+    public void disableBluetoothGetBondStateCache() {
+        mBluetoothBondCache.disableLocal();
+    }
+
+    /** @hide */
+    public static void invalidateBluetoothGetBondStateCache() {
+        PropertyInvalidatedCache.invalidateCache(BLUETOOTH_BONDING_CACHE_PROPERTY);
+    }
+
     /**
      * Get the bond state of the remote device.
      * <p>Possible values for the bond state are:
@@ -1316,9 +1342,13 @@ public final class BluetoothDevice implements Parcelable {
             return BOND_NONE;
         }
         try {
-            return service.getBondState(this);
-        } catch (RemoteException e) {
-            Log.e(TAG, "", e);
+            return mBluetoothBondCache.query(this);
+        } catch (RuntimeException e) {
+            if (e.getCause() instanceof RemoteException) {
+                Log.e(TAG, "", e);
+            } else {
+                throw e;
+            }
         }
         return BOND_NONE;
     }