Process AMS events in NetworkPolicy handler.

When a process changes foreground status or dies, NetworkPolicy
updates its internal state with a lock held.  In cases where there
is contention, this can block the AMS handler and prevent other
events, such as broadcasts, from being dispatched.

This change moves the incoming AMS events to an existing internal
NetworkPolicy handler thread, where they can execute without
blocking AMS.

Bug: 5497544
Change-Id: Ie0c620a620fd9f0f4eb02af510bd819efa4deb6a

Author: jsharkey

services/java/com/android/server/net/NetworkPolicyManagerService.java

@@ -186,8 +186,10 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
 
     private static final long TIME_CACHE_MAX_AGE = DAY_IN_MILLIS;
 
-    private static final int MSG_RULES_CHANGED = 0x1;
-    private static final int MSG_METERED_IFACES_CHANGED = 0x2;
+    private static final int MSG_RULES_CHANGED = 1;
+    private static final int MSG_METERED_IFACES_CHANGED = 2;
+    private static final int MSG_FOREGROUND_ACTIVITIES_CHANGED = 3;
+    private static final int MSG_PROCESS_DIED = 4;
 
     private final Context mContext;
     private final IActivityManager mActivityManager;
@@ -335,37 +337,13 @@ public void systemReady() {
     private IProcessObserver mProcessObserver = new IProcessObserver.Stub() {
         @Override
         public void onForegroundActivitiesChanged(int pid, int uid, boolean foregroundActivities) {
-            // only someone like AMS should only be calling us
-            mContext.enforceCallingOrSelfPermission(MANAGE_APP_TOKENS, TAG);
-
-            synchronized (mRulesLock) {
-                // because a uid can have multiple pids running inside, we need to
-                // remember all pid states and summarize foreground at uid level.
-
-                // record foreground for this specific pid
-                SparseBooleanArray pidForeground = mUidPidForeground.get(uid);
-                if (pidForeground == null) {
-                    pidForeground = new SparseBooleanArray(2);
-                    mUidPidForeground.put(uid, pidForeground);
-                }
-                pidForeground.put(pid, foregroundActivities);
-                computeUidForegroundLocked(uid);
-            }
+            mHandler.obtainMessage(MSG_FOREGROUND_ACTIVITIES_CHANGED,
+                    pid, uid, foregroundActivities).sendToTarget();
         }
 
         @Override
         public void onProcessDied(int pid, int uid) {
-            // only someone like AMS should only be calling us
-            mContext.enforceCallingOrSelfPermission(MANAGE_APP_TOKENS, TAG);
-
-            synchronized (mRulesLock) {
-                // clear records and recompute, when they exist
-                final SparseBooleanArray pidForeground = mUidPidForeground.get(uid);
-                if (pidForeground != null) {
-                    pidForeground.delete(pid);
-                    computeUidForegroundLocked(uid);
-                }
-            }
+            mHandler.obtainMessage(MSG_PROCESS_DIED, pid, uid).sendToTarget();
         }
     };
 
@@ -1469,6 +1447,40 @@ public boolean handleMessage(Message msg) {
                     mListeners.finishBroadcast();
                     return true;
                 }
+                case MSG_FOREGROUND_ACTIVITIES_CHANGED: {
+                    final int pid = msg.arg1;
+                    final int uid = msg.arg2;
+                    final boolean foregroundActivities = (Boolean) msg.obj;
+
+                    synchronized (mRulesLock) {
+                        // because a uid can have multiple pids running inside, we need to
+                        // remember all pid states and summarize foreground at uid level.
+
+                        // record foreground for this specific pid
+                        SparseBooleanArray pidForeground = mUidPidForeground.get(uid);
+                        if (pidForeground == null) {
+                            pidForeground = new SparseBooleanArray(2);
+                            mUidPidForeground.put(uid, pidForeground);
+                        }
+                        pidForeground.put(pid, foregroundActivities);
+                        computeUidForegroundLocked(uid);
+                    }
+                    return true;
+                }
+                case MSG_PROCESS_DIED: {
+                    final int pid = msg.arg1;
+                    final int uid = msg.arg2;
+
+                    synchronized (mRulesLock) {
+                        // clear records and recompute, when they exist
+                        final SparseBooleanArray pidForeground = mUidPidForeground.get(uid);
+                        if (pidForeground != null) {
+                            pidForeground.delete(pid);
+                            computeUidForegroundLocked(uid);
+                        }
+                    }
+                    return true;
+                }
                 default: {
                     return false;
                 }