From 98b8d31add0109b93b931ebc34f5a804f4940691 Mon Sep 17 00:00:00 2001
From: Fyodor Kupolov <fkupolov@google.com>
Date: Wed, 10 May 2017 16:31:21 -0700
Subject: [PATCH] Use buffered DataInputStream vs RandomAccessFile

Switching to buffered streams saved up to 50% of
BackupManagerService.onUnlockUser time:

Before:
SystemServiceManager: Service com.android.server.backup.BackupManagerService$Lifecycle took 389 ms in onUnlockUser
SystemServiceManager: Service com.android.server.backup.BackupManagerService$Lifecycle took 380 ms in onUnlockUser
After:
SystemServiceManager: Service com.android.server.backup.BackupManagerService$Lifecycle took 178 ms in onUnlockUser
SystemServiceManager: Service com.android.server.backup.BackupManagerService$Lifecycle took 155 ms in onUnlockUser

Test: manual
Bug: 37686433
Change-Id: I41185a88e8377b434fab6a3bf1fd7086758127cd
---
 .../server/backup/BackupManagerService.java   | 26 +++++++++----------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/services/backup/java/com/android/server/backup/BackupManagerService.java b/services/backup/java/com/android/server/backup/BackupManagerService.java
index d1a43d23f84f1..3f8d5083f1047 100644
--- a/services/backup/java/com/android/server/backup/BackupManagerService.java
+++ b/services/backup/java/com/android/server/backup/BackupManagerService.java
@@ -1397,23 +1397,22 @@ public class BackupManagerService {
 
         // Remember our ancestral dataset
         mTokenFile = new File(mBaseStateDir, "ancestral");
-        try {
-            RandomAccessFile tf = new RandomAccessFile(mTokenFile, "r");
-            int version = tf.readInt();
+        try (DataInputStream tokenStream = new DataInputStream(new BufferedInputStream(
+                new FileInputStream(mTokenFile)))) {
+            int version = tokenStream.readInt();
             if (version == CURRENT_ANCESTRAL_RECORD_VERSION) {
-                mAncestralToken = tf.readLong();
-                mCurrentToken = tf.readLong();
+                mAncestralToken = tokenStream.readLong();
+                mCurrentToken = tokenStream.readLong();
 
-                int numPackages = tf.readInt();
+                int numPackages = tokenStream.readInt();
                 if (numPackages >= 0) {
-                    mAncestralPackages = new HashSet<String>();
+                    mAncestralPackages = new HashSet<>();
                     for (int i = 0; i < numPackages; i++) {
-                        String pkgName = tf.readUTF();
+                        String pkgName = tokenStream.readUTF();
                         mAncestralPackages.add(pkgName);
                     }
                 }
             }
-            tf.close();
         } catch (FileNotFoundException fnf) {
             // Probably innocuous
             Slog.v(TAG, "No ancestral data");
@@ -1437,12 +1436,13 @@ public class BackupManagerService {
         // If there are previous contents, parse them out then start a new
         // file to continue the recordkeeping.
         if (mEverStored.exists()) {
-            RandomAccessFile temp = null;
-            RandomAccessFile in = null;
+            DataOutputStream temp = null;
+            DataInputStream in = null;
 
             try {
-                temp = new RandomAccessFile(tempProcessedFile, "rws");
-                in = new RandomAccessFile(mEverStored, "r");
+                temp = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(
+                        tempProcessedFile)));
+                in = new DataInputStream(new BufferedInputStream(new FileInputStream(mEverStored)));
 
                 // Loop until we hit EOF
                 while (true) {