Obfuscate usage stats data stored on disk.

All of the usage stats data stored on disk will now be obfuscated. There
will be a package to tokens mappings file stored on disk which has a
hierarchy of mappings for each string in each package's usage stats
data. A UsageStatsProtoV2 was added to keep the logic clean and separate
from the original usage stats proto parser.

Initial observations show a memory gain of over 60% w.r.t. the usage
stats data size on disk. There is also no performance hit because of this
change - in fact, even with the obfuscation overhead, reads are now over
65% faster and writes are up to 50% faster.

Bug: 135484470
Test: atest UsageStatsTest
Test: atest UsageStatsDatabaseTest
Test: atest UsageStatsDatabasePerfTest
Change-Id: I55ce729033d8b6e4051271802d57c72684053c32

tests/UsageStatsPerfTests/src/com/android/frameworks/perftests/usage/tests/UsageStatsDatabasePerfTest.java

@@ -30,6 +30,7 @@ import androidx.test.filters.LargeTest;
 import androidx.test.runner.AndroidJUnit4;
 
 import com.android.server.usage.IntervalStats;
+import com.android.server.usage.PackagesTokenData;
 import com.android.server.usage.UsageStatsDatabase;
 import com.android.server.usage.UsageStatsDatabase.StatCombiner;
 
@@ -140,6 +141,37 @@ public class UsageStatsDatabasePerfTest {
         }
     }
 
+    private void runObfuscateStatsTest(int packageCount, int eventsPerPackage) {
+        final ManualBenchmarkState benchmarkState = mPerfManualStatusReporter.getBenchmarkState();
+        IntervalStats intervalStats = new IntervalStats();
+        populateIntervalStats(intervalStats, packageCount, eventsPerPackage);
+        long elapsedTimeNs = 0;
+        while (benchmarkState.keepRunning(elapsedTimeNs)) {
+            final long startTime = SystemClock.elapsedRealtimeNanos();
+            PackagesTokenData packagesTokenData = new PackagesTokenData();
+            intervalStats.obfuscateData(packagesTokenData);
+            final long endTime = SystemClock.elapsedRealtimeNanos();
+            elapsedTimeNs = endTime - startTime;
+            clearUsageStatsFiles();
+        }
+    }
+
+    private void runDeobfuscateStatsTest(int packageCount, int eventsPerPackage) {
+        final ManualBenchmarkState benchmarkState = mPerfManualStatusReporter.getBenchmarkState();
+        IntervalStats intervalStats = new IntervalStats();
+        populateIntervalStats(intervalStats, packageCount, eventsPerPackage);
+        long elapsedTimeNs = 0;
+        while (benchmarkState.keepRunning(elapsedTimeNs)) {
+            PackagesTokenData packagesTokenData = new PackagesTokenData();
+            intervalStats.obfuscateData(packagesTokenData);
+            final long startTime = SystemClock.elapsedRealtimeNanos();
+            intervalStats.deobfuscateData(packagesTokenData);
+            final long endTime = SystemClock.elapsedRealtimeNanos();
+            elapsedTimeNs = endTime - startTime;
+            clearUsageStatsFiles();
+        }
+    }
+
     @Test
     public void testQueryUsageStats_FewPkgsLightUse() throws IOException {
         runQueryUsageStatsTest(FEW_PKGS, LIGHT_USE);
@@ -150,6 +182,16 @@ public class UsageStatsDatabasePerfTest {
         runPutUsageStatsTest(FEW_PKGS, LIGHT_USE);
     }
 
+    @Test
+    public void testObfuscateStats_FewPkgsLightUse() {
+        runObfuscateStatsTest(FEW_PKGS, LIGHT_USE);
+    }
+
+    @Test
+    public void testDeobfuscateStats_FewPkgsLightUse() {
+        runDeobfuscateStatsTest(FEW_PKGS, LIGHT_USE);
+    }
+
     @Test
     public void testQueryUsageStats_FewPkgsHeavyUse() throws IOException {
         runQueryUsageStatsTest(FEW_PKGS, HEAVY_USE);
@@ -160,6 +202,16 @@ public class UsageStatsDatabasePerfTest {
         runPutUsageStatsTest(FEW_PKGS, HEAVY_USE);
     }
 
+    @Test
+    public void testObfuscateStats_FewPkgsHeavyUse() {
+        runObfuscateStatsTest(FEW_PKGS, HEAVY_USE);
+    }
+
+    @Test
+    public void testDeobfuscateStats_FewPkgsHeavyUse() {
+        runDeobfuscateStatsTest(FEW_PKGS, HEAVY_USE);
+    }
+
     @Test
     public void testQueryUsageStats_ManyPkgsLightUse() throws IOException {
         runQueryUsageStatsTest(MANY_PKGS, LIGHT_USE);
@@ -170,6 +222,16 @@ public class UsageStatsDatabasePerfTest {
         runPutUsageStatsTest(MANY_PKGS, LIGHT_USE);
     }
 
+    @Test
+    public void testObfuscateStats_ManyPkgsLightUse() {
+        runObfuscateStatsTest(MANY_PKGS, LIGHT_USE);
+    }
+
+    @Test
+    public void testDeobfuscateStats_ManyPkgsLightUse() {
+        runDeobfuscateStatsTest(MANY_PKGS, LIGHT_USE);
+    }
+
     @Test
     public void testQueryUsageStats_ManyPkgsHeavyUse() throws IOException {
         runQueryUsageStatsTest(MANY_PKGS, HEAVY_USE);
@@ -179,4 +241,14 @@ public class UsageStatsDatabasePerfTest {
     public void testPutUsageStats_ManyPkgsHeavyUse() throws IOException {
         runPutUsageStatsTest(MANY_PKGS, HEAVY_USE);
     }
+
+    @Test
+    public void testObfuscateStats_ManyPkgsHeavyUse() {
+        runObfuscateStatsTest(MANY_PKGS, HEAVY_USE);
+    }
+
+    @Test
+    public void testDeobfuscateStats_ManyPkgsHeavyUse() {
+        runDeobfuscateStatsTest(MANY_PKGS, HEAVY_USE);
+    }
 }