INetworkStatsSession with lifecycle for caching.

Users outside system_server now explicitly communicate their
lifecycle, which keeps a strong-reference chain to any fully loaded
NetworkStatsCollection histories.

Bug: 6236498
Change-Id: I8e22739b6e89a626b676967a736d7117fd000778

core/java/android/net/INetworkStatsService.aidl

@@ -16,6 +16,7 @@
 
 package android.net;
 
+import android.net.INetworkStatsSession;
 import android.net.NetworkStats;
 import android.net.NetworkStatsHistory;
 import android.net.NetworkTemplate;
@@ -23,15 +24,11 @@ import android.net.NetworkTemplate;
 /** {@hide} */
 interface INetworkStatsService {
 
-    /** Return historical network layer stats for traffic that matches template. */
-    NetworkStatsHistory getHistoryForNetwork(in NetworkTemplate template, int fields);
-    /** Return historical network layer stats for specific UID traffic that matches template. */
-    NetworkStatsHistory getHistoryForUid(in NetworkTemplate template, int uid, int set, int tag, int fields);
+    /** Start a statistics query session. */
+    INetworkStatsSession openSession();
 
-    /** Return network layer usage summary for traffic that matches template. */
-    NetworkStats getSummaryForNetwork(in NetworkTemplate template, long start, long end);
-    /** Return network layer usage summary per UID for traffic that matches template. */
-    NetworkStats getSummaryForAllUid(in NetworkTemplate template, long start, long end, boolean includeTags);
+    /** Return network layer usage total for traffic that matches template. */
+    long getNetworkTotalBytes(in NetworkTemplate template, long start, long end);
 
     /** Return data layer snapshot of UID network usage. */
     NetworkStats getDataLayerSnapshotForUid(int uid);

core/java/android/net/INetworkStatsSession.aidl

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.net;
+
+import android.net.NetworkStats;
+import android.net.NetworkStatsHistory;
+import android.net.NetworkTemplate;
+
+/** {@hide} */
+interface INetworkStatsSession {
+
+    /** Return network layer usage summary for traffic that matches template. */
+    NetworkStats getSummaryForNetwork(in NetworkTemplate template, long start, long end);
+    /** Return historical network layer stats for traffic that matches template. */
+    NetworkStatsHistory getHistoryForNetwork(in NetworkTemplate template, int fields);
+
+    /** Return network layer usage summary per UID for traffic that matches template. */
+    NetworkStats getSummaryForAllUid(in NetworkTemplate template, long start, long end, boolean includeTags);
+    /** Return historical network layer stats for specific UID traffic that matches template. */
+    NetworkStatsHistory getHistoryForUid(in NetworkTemplate template, int uid, int set, int tag, int fields);
+
+    void close();
+
+}

core/java/android/net/TrafficStats.java

@@ -238,6 +238,19 @@ public class TrafficStats {
         }
     }
 
+    /** {@hide} */
+    public static void closeQuietly(INetworkStatsSession session) {
+        // TODO: move to NetworkStatsService once it exists
+        if (session != null) {
+            try {
+                session.close();
+            } catch (RuntimeException rethrown) {
+                throw rethrown;
+            } catch (Exception ignored) {
+            }
+        }
+    }
+
     /**
      * Get the total number of packets transmitted through the mobile interface.
      *