Add playback session class

Test: make;
Bug: 167036690
Change-Id: Iea7c1f76fcabeac9a48082d22d0d06cddd60a5de

media/java/android/media/metrics/IPlaybackMetricsManager.aidl

@@ -23,5 +23,6 @@ import android.media.metrics.PlaybackMetrics;
  * @hide
  */
 interface IPlaybackMetricsManager {
-    void reportPlaybackMetrics(in PlaybackMetrics metrics, int userId);
+    void reportPlaybackMetrics(in String sessionId, in PlaybackMetrics metrics, int userId);
+    String getSessionId(int userId);
 }

media/java/android/media/metrics/PlaybackMetricsManager.java

@@ -16,6 +16,7 @@
 
 package android.media.metrics;
 
+import android.annotation.NonNull;
 import android.os.RemoteException;
 
 /**
@@ -38,10 +39,24 @@ public class PlaybackMetricsManager {
 
     /**
      * Reports playback metrics.
+     * @hide
      */
-    public void reportPlaybackMetrics(PlaybackMetrics metrics) {
+    public void reportPlaybackMetrics(@NonNull String sessionId, PlaybackMetrics metrics) {
         try {
-            mService.reportPlaybackMetrics(metrics, mUserId);
+            mService.reportPlaybackMetrics(sessionId, metrics, mUserId);
+        } catch (RemoteException e) {
+            throw e.rethrowFromSystemServer();
+        }
+    }
+
+    /**
+     * Creates a playback session.
+     */
+    public PlaybackSession createSession() {
+        try {
+            String id = mService.getSessionId(mUserId);
+            PlaybackSession session = new PlaybackSession(id, this);
+            return session;
         } catch (RemoteException e) {
             throw e.rethrowFromSystemServer();
         }

media/java/android/media/metrics/PlaybackSession.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2020 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.media.metrics;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+
+import com.android.internal.util.AnnotationValidations;
+
+import java.util.Objects;
+
+/**
+ * @hide
+ */
+public final class PlaybackSession implements AutoCloseable {
+    private final @NonNull String mId;
+    private final @NonNull PlaybackMetricsManager mManager;
+    private boolean mClosed = false;
+
+    /**
+     * Creates a new PlaybackSession.
+     *
+     * @hide
+     */
+    public PlaybackSession(@NonNull String id, @NonNull PlaybackMetricsManager manager) {
+        mId = id;
+        mManager = manager;
+        AnnotationValidations.validate(NonNull.class, null, mId);
+        AnnotationValidations.validate(NonNull.class, null, mManager);
+    }
+
+    /**
+     * Reports playback metrics.
+     */
+    public void reportPlaybackMetrics(@NonNull PlaybackMetrics metrics) {
+        mManager.reportPlaybackMetrics(mId, metrics);
+    }
+
+    public @NonNull String getId() {
+        return mId;
+    }
+
+    @Override
+    public boolean equals(@Nullable Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        PlaybackSession that = (PlaybackSession) o;
+        return Objects.equals(mId, that.mId);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(mId);
+    }
+
+    @Override
+    public void close() throws Exception {
+        mClosed = true;
+    }
+}

services/core/java/com/android/server/media/metrics/PlaybackMetricsManagerService.java

@@ -19,13 +19,17 @@ package com.android.server.media.metrics;
 import android.content.Context;
 import android.media.metrics.IPlaybackMetricsManager;
 import android.media.metrics.PlaybackMetrics;
+import android.util.Base64;
 
 import com.android.server.SystemService;
 
+import java.security.SecureRandom;
+
 /**
  * System service manages playback metrics.
  */
 public final class PlaybackMetricsManagerService extends SystemService {
+    private final SecureRandom mSecureRandom;
 
     /**
      * Initializes the playback metrics manager service.
@@ -34,6 +38,7 @@ public final class PlaybackMetricsManagerService extends SystemService {
      */
     public PlaybackMetricsManagerService(Context context) {
         super(context);
+        mSecureRandom = new SecureRandom();
     }
 
     @Override
@@ -44,8 +49,16 @@ public final class PlaybackMetricsManagerService extends SystemService {
 
     private final class BinderService extends IPlaybackMetricsManager.Stub {
         @Override
-        public void reportPlaybackMetrics(PlaybackMetrics metrics, int userId) {
+        public void reportPlaybackMetrics(String sessionId, PlaybackMetrics metrics, int userId) {
             // TODO: log it to statsd
         }
+
+        @Override
+        public String getSessionId(int userId) {
+            byte[] byteId = new byte[16]; // 128 bits
+            mSecureRandom.nextBytes(byteId);
+            String id = Base64.encodeToString(byteId, Base64.DEFAULT);
+            return id;
+        }
     }
 }