From e4d1cd970e74f56c45d428acd6fca2df45dd2cda Mon Sep 17 00:00:00 2001
From: Remi NGUYEN VAN <reminv@google.com>
Date: Thu, 17 Jun 2021 16:27:31 +0900
Subject: [PATCH] Initialize TetheringManager lazily

Many applications use ConnectivityManager without needing
TetheringManager (or without calling legacy ConnectivityManager methods
that delegate to TetheringManager), so initializing TetheringManager
when ConnectivityManager is created wastes resources.

This is especially true considering that TetheringManager is not trivial
to initialize (worst case scenario it starts a thread and does multiple
Binder requests), and ConnectivityManager is created in ActivityThread
when setting up the app proxy on startup.

Bug: 190556328
Test: atest FrameworksNetTests CtsNetTestCases TetheringTests
Change-Id: I2ba7b8f2b9e1c934cfb082776b8d643f2f2c17e5
---
 .../src/android/net/ConnectivityManager.java  | 47 +++++++++++--------
 1 file changed, 28 insertions(+), 19 deletions(-)

diff --git a/framework/src/android/net/ConnectivityManager.java b/framework/src/android/net/ConnectivityManager.java
index 20f38533cb..b8f8aaea8c 100644
--- a/framework/src/android/net/ConnectivityManager.java
+++ b/framework/src/android/net/ConnectivityManager.java
@@ -936,7 +936,17 @@ public class ConnectivityManager {
 
     private final Context mContext;
 
-    private final TetheringManager mTetheringManager;
+    @GuardedBy("mTetheringEventCallbacks")
+    private TetheringManager mTetheringManager;
+
+    private TetheringManager getTetheringManager() {
+        synchronized (mTetheringEventCallbacks) {
+            if (mTetheringManager == null) {
+                mTetheringManager = mContext.getSystemService(TetheringManager.class);
+            }
+            return mTetheringManager;
+        }
+    }
 
     /**
      * Tests if a given integer represents a valid network type.
@@ -2386,7 +2396,6 @@ public class ConnectivityManager {
     public ConnectivityManager(Context context, IConnectivityManager service) {
         mContext = Objects.requireNonNull(context, "missing context");
         mService = Objects.requireNonNull(service, "missing IConnectivityManager");
-        mTetheringManager = (TetheringManager) mContext.getSystemService(Context.TETHERING_SERVICE);
         sInstance = this;
     }
 
@@ -2457,7 +2466,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage
     @Deprecated
     public String[] getTetherableIfaces() {
-        return mTetheringManager.getTetherableIfaces();
+        return getTetheringManager().getTetherableIfaces();
     }
 
     /**
@@ -2472,7 +2481,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage
     @Deprecated
     public String[] getTetheredIfaces() {
-        return mTetheringManager.getTetheredIfaces();
+        return getTetheringManager().getTetheredIfaces();
     }
 
     /**
@@ -2493,7 +2502,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage
     @Deprecated
     public String[] getTetheringErroredIfaces() {
-        return mTetheringManager.getTetheringErroredIfaces();
+        return getTetheringManager().getTetheringErroredIfaces();
     }
 
     /**
@@ -2537,7 +2546,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
     @Deprecated
     public int tether(String iface) {
-        return mTetheringManager.tether(iface);
+        return getTetheringManager().tether(iface);
     }
 
     /**
@@ -2561,7 +2570,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage
     @Deprecated
     public int untether(String iface) {
-        return mTetheringManager.untether(iface);
+        return getTetheringManager().untether(iface);
     }
 
     /**
@@ -2587,7 +2596,7 @@ public class ConnectivityManager {
     @RequiresPermission(anyOf = {android.Manifest.permission.TETHER_PRIVILEGED,
             android.Manifest.permission.WRITE_SETTINGS})
     public boolean isTetheringSupported() {
-        return mTetheringManager.isTetheringSupported();
+        return getTetheringManager().isTetheringSupported();
     }
 
     /**
@@ -2680,7 +2689,7 @@ public class ConnectivityManager {
         final TetheringRequest request = new TetheringRequest.Builder(type)
                 .setShouldShowEntitlementUi(showProvisioningUi).build();
 
-        mTetheringManager.startTethering(request, executor, tetheringCallback);
+        getTetheringManager().startTethering(request, executor, tetheringCallback);
     }
 
     /**
@@ -2699,7 +2708,7 @@ public class ConnectivityManager {
     @Deprecated
     @RequiresPermission(android.Manifest.permission.TETHER_PRIVILEGED)
     public void stopTethering(int type) {
-        mTetheringManager.stopTethering(type);
+        getTetheringManager().stopTethering(type);
     }
 
     /**
@@ -2757,7 +2766,7 @@ public class ConnectivityManager {
 
         synchronized (mTetheringEventCallbacks) {
             mTetheringEventCallbacks.put(callback, tetherCallback);
-            mTetheringManager.registerTetheringEventCallback(executor, tetherCallback);
+            getTetheringManager().registerTetheringEventCallback(executor, tetherCallback);
         }
     }
 
@@ -2779,7 +2788,7 @@ public class ConnectivityManager {
         synchronized (mTetheringEventCallbacks) {
             final TetheringEventCallback tetherCallback =
                     mTetheringEventCallbacks.remove(callback);
-            mTetheringManager.unregisterTetheringEventCallback(tetherCallback);
+            getTetheringManager().unregisterTetheringEventCallback(tetherCallback);
         }
     }
 
@@ -2799,7 +2808,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage
     @Deprecated
     public String[] getTetherableUsbRegexs() {
-        return mTetheringManager.getTetherableUsbRegexs();
+        return getTetheringManager().getTetherableUsbRegexs();
     }
 
     /**
@@ -2817,7 +2826,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage
     @Deprecated
     public String[] getTetherableWifiRegexs() {
-        return mTetheringManager.getTetherableWifiRegexs();
+        return getTetheringManager().getTetherableWifiRegexs();
     }
 
     /**
@@ -2836,7 +2845,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage
     @Deprecated
     public String[] getTetherableBluetoothRegexs() {
-        return mTetheringManager.getTetherableBluetoothRegexs();
+        return getTetheringManager().getTetherableBluetoothRegexs();
     }
 
     /**
@@ -2860,7 +2869,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage
     @Deprecated
     public int setUsbTethering(boolean enable) {
-        return mTetheringManager.setUsbTethering(enable);
+        return getTetheringManager().setUsbTethering(enable);
     }
 
     /**
@@ -2976,7 +2985,7 @@ public class ConnectivityManager {
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
     @Deprecated
     public int getLastTetherError(String iface) {
-        int error = mTetheringManager.getLastTetherError(iface);
+        int error = getTetheringManager().getLastTetherError(iface);
         if (error == TetheringManager.TETHER_ERROR_UNKNOWN_TYPE) {
             // TETHER_ERROR_UNKNOWN_TYPE was introduced with TetheringManager and has never been
             // returned by ConnectivityManager. Convert it to the legacy TETHER_ERROR_UNKNOWN_IFACE
@@ -3058,7 +3067,7 @@ public class ConnectivityManager {
             }
         };
 
-        mTetheringManager.requestLatestTetheringEntitlementResult(type, wrappedListener,
+        getTetheringManager().requestLatestTetheringEntitlementResult(type, wrappedListener,
                     showEntitlementUi);
     }
 
@@ -4840,7 +4849,7 @@ public class ConnectivityManager {
     public void factoryReset() {
         try {
             mService.factoryReset();
-            mTetheringManager.stopAllTethering();
+            getTetheringManager().stopAllTethering();
         } catch (RemoteException e) {
             throw e.rethrowFromSystemServer();
         }