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. */
+    /** Start a statistics query session. */
-    NetworkStatsHistory getHistoryForNetwork(in NetworkTemplate template, int fields);
+    INetworkStatsSession openSession();
-    /** 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);
 
-    /** Return network layer usage summary for traffic that matches template. */
+    /** Return network layer usage total for traffic that matches template. */
-    NetworkStats getSummaryForNetwork(in NetworkTemplate template, long start, long end);
+    long getNetworkTotalBytes(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 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.
      *

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

@@ -221,6 +221,11 @@ public class NetworkStatsRecorder {
         if (mLastSnapshot != null) {
             mLastSnapshot = mLastSnapshot.withoutUid(uid);
         }
+
+        final NetworkStatsCollection complete = mComplete != null ? mComplete.get() : null;
+        if (complete != null) {
+            complete.removeUid(uid);
+        }
     }
 
     /**

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

@@ -70,6 +70,7 @@ import android.content.IntentFilter;
 import android.net.IConnectivityManager;
 import android.net.INetworkManagementEventObserver;
 import android.net.INetworkStatsService;
+import android.net.INetworkStatsSession;
 import android.net.LinkProperties;
 import android.net.NetworkIdentity;
 import android.net.NetworkInfo;
@@ -412,40 +413,75 @@ public class NetworkStatsService extends INetworkStatsService.Stub {
     }
 
     @Override
-    public NetworkStatsHistory getHistoryForNetwork(NetworkTemplate template, int fields) {
+    public INetworkStatsSession openSession() {
-        return mDevStatsCached.getHistory(template, UID_ALL, SET_ALL, TAG_NONE, fields);
+        mContext.enforceCallingOrSelfPermission(READ_NETWORK_USAGE_HISTORY, TAG);
+
+        // return an IBinder which holds strong references to any loaded stats
+        // for its lifetime; when caller closes only weak references remain.
+
+        return new INetworkStatsSession.Stub() {
+            private NetworkStatsCollection mUidComplete;
+            private NetworkStatsCollection mUidTagComplete;
+
+            private NetworkStatsCollection getUidComplete() {
+                if (mUidComplete == null) {
+                    mUidComplete = mUidRecorder.getOrLoadCompleteLocked();
+                }
+                return mUidComplete;
+            }
+
+            private NetworkStatsCollection getUidTagComplete() {
+                if (mUidTagComplete == null) {
+                    mUidTagComplete = mUidTagRecorder.getOrLoadCompleteLocked();
+                }
+                return mUidTagComplete;
+            }
+
+            @Override
+            public NetworkStats getSummaryForNetwork(
+                    NetworkTemplate template, long start, long end) {
+                return mDevStatsCached.getSummary(template, start, end);
+            }
+
+            @Override
+            public NetworkStatsHistory getHistoryForNetwork(NetworkTemplate template, int fields) {
+                return mDevStatsCached.getHistory(template, UID_ALL, SET_ALL, TAG_NONE, fields);
+            }
+
+            @Override
+            public NetworkStats getSummaryForAllUid(
+                    NetworkTemplate template, long start, long end, boolean includeTags) {
+                final NetworkStats stats = getUidComplete().getSummary(template, start, end);
+                if (includeTags) {
+                    final NetworkStats tagStats = getUidTagComplete()
+                            .getSummary(template, start, end);
+                    stats.combineAllValues(tagStats);
+                }
+                return stats;
+            }
+
+            @Override
+            public NetworkStatsHistory getHistoryForUid(
+                    NetworkTemplate template, int uid, int set, int tag, int fields) {
+                if (tag == TAG_NONE) {
+                    return getUidComplete().getHistory(template, uid, set, tag, fields);
+                } else {
+                    return getUidTagComplete().getHistory(template, uid, set, tag, fields);
+                }
+            }
+
+            @Override
+            public void close() {
+                mUidComplete = null;
+                mUidTagComplete = null;
+            }
+        };
     }
 
     @Override
-    public NetworkStats getSummaryForNetwork(NetworkTemplate template, long start, long end) {
+    public long getNetworkTotalBytes(NetworkTemplate template, long start, long end) {
-        return mDevStatsCached.getSummary(template, start, end);
+        mContext.enforceCallingOrSelfPermission(READ_NETWORK_USAGE_HISTORY, TAG);
-    }
+        return mDevStatsCached.getSummary(template, start, end).getTotalBytes();
-
-    @Override
-    public NetworkStatsHistory getHistoryForUid(
-            NetworkTemplate template, int uid, int set, int tag, int fields) {
-        // TODO: transition to stats sessions to avoid WeakReferences
-        if (tag == TAG_NONE) {
-            return mUidRecorder.getOrLoadCompleteLocked().getHistory(
-                    template, uid, set, tag, fields);
-        } else {
-            return mUidTagRecorder.getOrLoadCompleteLocked().getHistory(
-                    template, uid, set, tag, fields);
-        }
-    }
-
-    @Override
-    public NetworkStats getSummaryForAllUid(
-            NetworkTemplate template, long start, long end, boolean includeTags) {
-        // TODO: transition to stats sessions to avoid WeakReferences
-        final NetworkStats stats = mUidRecorder.getOrLoadCompleteLocked().getSummary(
-                template, start, end);
-        if (includeTags) {
-            final NetworkStats tagStats = mUidTagRecorder.getOrLoadCompleteLocked().getSummary(
-                    template, start, end);
-            stats.combineAllValues(tagStats);
-        }
-        return stats;
     }
 
     @Override