2 files changed, 89 insertions, 4 deletions

diff --git a/core/java/android/app/AppCompatCallbacks.java b/core/java/android/app/AppCompatCallbacks.java
index 17697dba9ccd..08c97eb284e3 100644
--- a/core/java/android/app/AppCompatCallbacks.java
+++ b/core/java/android/app/AppCompatCallbacks.java
@@ -19,6 +19,9 @@ package android.app;
 import android.compat.Compatibility;
 import android.os.Process;
 import android.util.Log;
+import android.util.StatsLog;
+
+import com.android.internal.compat.ChangeReporter;
 
 import java.util.Arrays;
 
@@ -28,10 +31,10 @@ import java.util.Arrays;
  * @hide
  */
 public final class AppCompatCallbacks extends Compatibility.Callbacks {
-
     private static final String TAG = "Compatibility";
 
     private final long[] mDisabledChanges;
+    private final ChangeReporter mChangeReporter;
 
     /**
      * Install this class into the current process.
@@ -45,20 +48,29 @@ public final class AppCompatCallbacks extends Compatibility.Callbacks {
     private AppCompatCallbacks(long[] disabledChanges) {
         mDisabledChanges = Arrays.copyOf(disabledChanges, disabledChanges.length);
         Arrays.sort(mDisabledChanges);
+        mChangeReporter = new ChangeReporter();
     }
 
     protected void reportChange(long changeId) {
-        Log.d(TAG, "Compat change reported: " + changeId + "; UID " + Process.myUid());
-        // TODO log via StatsLog
+        reportChange(changeId, StatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__LOGGED);
     }
 
     protected boolean isChangeEnabled(long changeId) {
         if (Arrays.binarySearch(mDisabledChanges, changeId) < 0) {
             // Not present in the disabled array
-            reportChange(changeId);
+            reportChange(changeId, StatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__ENABLED);
             return true;
         }
+        reportChange(changeId, StatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__DISABLED);
         return false;
     }
 
+    private void reportChange(long changeId, int state) {
+        int uid = Process.myUid();
+        //TODO(b/138374585): Implement rate limiting for the logs.
+        Log.d(TAG, ChangeReporter.createLogString(uid, changeId, state));
+        mChangeReporter.reportChange(uid, changeId,
+                state, /* source */StatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__SOURCE__APP_PROCESS);
+    }
+
 }
diff --git a/core/java/com/android/internal/compat/ChangeReporter.java b/core/java/com/android/internal/compat/ChangeReporter.java
new file mode 100644
index 000000000000..1ce071bd005a
--- /dev/null
+++ b/core/java/com/android/internal/compat/ChangeReporter.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2019 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 com.android.internal.compat;
+
+import android.util.StatsLog;
+
+/**
+ * A helper class to report changes to stats log.
+ *
+ * @hide
+ */
+public final class ChangeReporter {
+
+    /**
+     * Transforms StatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE enum to a string.
+     *
+     * @param state to transform
+     * @return a string representing the state
+     */
+    private static String stateToString(int state) {
+        switch (state) {
+            case StatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__LOGGED:
+                return "LOGGED";
+            case StatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__ENABLED:
+                return "ENABLED";
+            case StatsLog.APP_COMPATIBILITY_CHANGE_REPORTED__STATE__DISABLED:
+                return "DISABLED";
+            default:
+                return "UNKNOWN";
+        }
+    }
+
+    /**
+     * Constructs and returns a string to be logged to logcat when a change is reported.
+     *
+     * @param uid      affected by the change
+     * @param changeId the reported change id
+     * @param state    of the reported change - enabled/disabled/only logged
+     * @return string to log
+     */
+    public static String createLogString(int uid, long changeId, int state) {
+        return String.format("Compat change id reported: %d; UID %d; state: %s", changeId, uid,
+                stateToString(state));
+    }
+
+    /**
+     * Report the change to stats log.
+     *
+     * @param uid      affected by the change
+     * @param changeId the reported change id
+     * @param state    of the reported change - enabled/disabled/only logged
+     * @param source   of the logging - app process or system server
+     */
+    public void reportChange(int uid, long changeId, int state, int source) {
+        //TODO(b/138374585): Implement rate limiting for stats log.
+        StatsLog.write(StatsLog.APP_COMPATIBILITY_CHANGE_REPORTED, uid, changeId,
+                state, source);
+    }
+}