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Commit cde87f45 authored by Christopher Tate's avatar Christopher Tate
Browse files

Journal backup requests so that they won't be lost in a crash 

When an application requests a backup via dataChanged(), we now journal that
fact on disk.  The journal persists and is only removed following a successful
backup pass.  When the backup manager is started at boot time, it looks for any
existing journal files and schedules a backup for the apps listed in them, on
the expectation that the device shut down or crashed before a backup could be
performed.
parent 0b774530

services/java/com/android/server/BackupManagerService.java

+94 −5
Original line number Diff line number Diff line
@@ -51,11 +51,13 @@ import com.android.internal.backup.LocalTransport; 
import com.android.internal.backup.GoogleTransport;

import com.android.internal.backup.IBackupTransport;



import java.io.EOFException;

import java.io.File;

import java.io.FileDescriptor;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.PrintWriter;

import java.io.RandomAccessFile;

import java.lang.String;

import java.util.ArrayList;

import java.util.HashMap;
@@ -122,6 +124,9 @@ class BackupManagerService extends IBackupManager.Stub { 


    private File mStateDir;

    private File mDataDir;

    private File mJournalDir;

    private File mJournal;

    private RandomAccessFile mJournalStream;

    

    public BackupManagerService(Context context) {

        mContext = context;
@@ -133,6 +138,11 @@ class BackupManagerService extends IBackupManager.Stub { 
        mStateDir.mkdirs();

        mDataDir = Environment.getDownloadCacheDirectory();



        // Set up the backup-request journaling

        mJournalDir = new File(mStateDir, "pending");

        mJournalDir.mkdirs();

        makeJournalLocked();    // okay because no other threads are running yet



        //!!! TODO: default to cloud transport, not local

        mTransportId = BackupManager.TRANSPORT_LOCAL;
@@ -141,6 +151,10 @@ class BackupManagerService extends IBackupManager.Stub { 
            addPackageParticipantsLocked(null);

        }



        // Now that we know about valid backup participants, parse any

        // leftover journal files and schedule a new backup pass

        parseLeftoverJournals();



        // Register for broadcasts about package install, etc., so we can

        // update the provider list.

        IntentFilter filter = new IntentFilter();
@@ -150,6 +164,46 @@ class BackupManagerService extends IBackupManager.Stub { 
        mContext.registerReceiver(mBroadcastReceiver, filter);

    }



    private void makeJournalLocked() {

        try {

            mJournal = File.createTempFile("journal", null, mJournalDir);

            mJournalStream = new RandomAccessFile(mJournal, "rwd");

        } catch (IOException e) {

            Log.e(TAG, "Unable to write backup journals");

            mJournal = null;

            mJournalStream = null;

        }

    }



    private void parseLeftoverJournals() {

        if (mJournal != null) {

            File[] allJournals = mJournalDir.listFiles();

            for (File f : allJournals) {

                if (f.compareTo(mJournal) != 0) {

                    // This isn't the current journal, so it must be a leftover.  Read

                    // out the package names mentioned there and schedule them for

                    // backup.

                    try {

                        Log.i(TAG, "Found stale backup journal, scheduling:");

                        RandomAccessFile in = new RandomAccessFile(f, "r");

                        while (true) {

                            String packageName = in.readUTF();

                            Log.i(TAG, "    + " + packageName);

                            dataChanged(packageName);

                        }

                    } catch (EOFException e) {

                        // no more data; we're done

                    } catch (Exception e) {

                        // can't read it or other error; just skip it

                    } finally {

                        // close/delete the file

                        f.delete();

                    }

                }

            }

        }

    }



    // ----- Track installation/removal of packages -----

    BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {

        public void onReceive(Context context, Intent intent) {
@@ -198,6 +252,8 @@ class BackupManagerService extends IBackupManager.Stub { 
            switch (msg.what) {

            case MSG_RUN_BACKUP:

                // snapshot the pending-backup set and work on that

                File oldJournal = mJournal;

                RandomAccessFile oldJournalStream = mJournalStream;

                synchronized (mQueueLock) {

                    if (mBackupQueue == null) {

                        mBackupQueue = new ArrayList<BackupRequest>();
@@ -207,10 +263,22 @@ class BackupManagerService extends IBackupManager.Stub { 
                        mPendingBackups = new HashMap<ApplicationInfo,BackupRequest>();

                    }

                    // !!! TODO: start a new backup-queue journal file too

                    // WARNING: If we crash after this line, anything in mPendingBackups will

                    // be lost.  FIX THIS.

                    if (mJournalStream != null) {

                        try {

                            mJournalStream.close();

                        } catch (IOException e) {

                            // don't need to do anything

                        }

                        makeJournalLocked();

                    }



                    // At this point, we have started a new journal file, and the old

                    // file identity is being passed to the backup processing thread.

                    // When it completes successfully, that old journal file will be

                    // deleted.  If we crash prior to that, the old journal is parsed

                    // at next boot and the journaled requests fulfilled.

                }

                (new PerformBackupThread(mTransportId, mBackupQueue)).run();

                (new PerformBackupThread(mTransportId, mBackupQueue, oldJournal)).run();

                break;



            case MSG_RUN_FULL_BACKUP:
@@ -433,10 +501,13 @@ class BackupManagerService extends IBackupManager.Stub { 
        private static final String TAG = "PerformBackupThread";

        int mTransport;

        ArrayList<BackupRequest> mQueue;

        File mJournal;



        public PerformBackupThread(int transportId, ArrayList<BackupRequest> queue) {

        public PerformBackupThread(int transportId, ArrayList<BackupRequest> queue,

                File journal) {

            mTransport = transportId;

            mQueue = queue;

            mJournal = journal;

        }



        @Override
@@ -468,6 +539,10 @@ class BackupManagerService extends IBackupManager.Stub { 
                Log.e(TAG, "Error ending transport");

                e.printStackTrace();

            }



            if (!mJournal.delete()) {

                Log.e(TAG, "Unable to remove backup journal file " + mJournal.getAbsolutePath());

            }

        }



        private void doQueuedBackups(IBackupTransport transport) {
@@ -782,7 +857,9 @@ class BackupManagerService extends IBackupManager.Stub { 
                        // one already there, then overwrite it, but no harm done.

                        BackupRequest req = new BackupRequest(app, false);

                        mPendingBackups.put(app, req);

                        // !!! TODO: write to the pending-backup journal file in case of crash



                        // Journal this request in case of crash

                        writeToJournalLocked(packageName);

                    }

                }
@@ -804,6 +881,18 @@ class BackupManagerService extends IBackupManager.Stub { 
        }

    }



    private void writeToJournalLocked(String str) {

        if (mJournalStream != null) {

            try {

                mJournalStream.writeUTF(str);

            } catch (IOException e) {

                Log.e(TAG, "Error writing to backup journal");

                mJournalStream = null;

                mJournal = null;

            }

        }

    }



    // Schedule a backup pass for a given package.  This method will schedule a

    // full backup even for apps that do not declare an android:backupAgent, so

    // use with care.