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Commit b5607824 authored by Joël Stemmer's avatar Joël Stemmer
Browse files

Add `onMeasureFullBackup` method to `BackupAgent` 

When backing up, a preflight check is performed that checks the size of
the backup against the backup quota. By default, the backup agent
measures the size of a backup by performing a full backup and discarding
the backed up data. This means for a normal backup session, the
`BackupAgent#onFullBackup` is called twice. For most backup agents this
is fine, as they won't have much data to back up.

We want to give apps that back up a lot of data (for example, during D2D
where the backup quota is multiple gigabytes) the possibility to provide
their own implementation of measuring the backup size so they can
provide a more efficient implementation if needed.

Bug: 403956528
Test: atest BackupAgentTest.java
Test: atest MeasureFullBackupTest.java (cts test added in same topic)
Flag: com.android.server.backup.enable_cross_platform_transfer
Change-Id: If6a869e772d433acc770f47f4aa05f54c54d3c0e
parent f2011b57

core/api/current.txt

+1 −0
Original line number Diff line number Diff line
@@ -9283,6 +9283,7 @@ package android.app.backup { 
    method public void onCreate();

    method public void onDestroy();

    method public void onFullBackup(android.app.backup.FullBackupDataOutput) throws java.io.IOException;

    method @FlaggedApi("com.android.server.backup.enable_cross_platform_transfer") public long onMeasureFullBackup(long, int) throws java.io.IOException;

    method public void onQuotaExceeded(long, long);

    method public abstract void onRestore(android.app.backup.BackupDataInput, int, android.os.ParcelFileDescriptor) throws java.io.IOException;

    method public void onRestore(android.app.backup.BackupDataInput, long, android.os.ParcelFileDescriptor) throws java.io.IOException;

core/java/android/app/backup/BackupAgent.java

+39 −6
Original line number Diff line number Diff line
@@ -159,8 +159,8 @@ public abstract class BackupAgent extends ContextWrapper { 
    public static final int TYPE_SYMLINK = 3;



    /**

     * Flag for {@link BackupDataOutput#getTransportFlags()} and {@link

     * FullBackupDataOutput#getTransportFlags()} only.

     * Flag for {@link BackupDataOutput#getTransportFlags()}, {@link

     * FullBackupDataOutput#getTransportFlags()} and {@link #onMeasureFullBackup(long, int)} only.

     *

     * <p>The transport has client-side encryption enabled. i.e., the user's backup has been

     * encrypted with a key known only to the device, and not to the remote storage solution. Even
@@ -170,8 +170,8 @@ public abstract class BackupAgent extends ContextWrapper { 
    public static final int FLAG_CLIENT_SIDE_ENCRYPTION_ENABLED = 1;



    /**

     * Flag for {@link BackupDataOutput#getTransportFlags()} and {@link

     * FullBackupDataOutput#getTransportFlags()} only.

     * Flag for {@link BackupDataOutput#getTransportFlags()}, {@link

     * FullBackupDataOutput#getTransportFlags()} and {@link #onMeasureFullBackup(long, int)} only.

     *

     * <p>The transport is for a device-to-device transfer. There is no third party or intermediate

     * storage. The user's backup data is sent directly to another device over e.g., USB or WiFi.
@@ -624,6 +624,26 @@ public abstract class BackupAgent extends ContextWrapper { 
        return new IncludeExcludeRules(manifestIncludeMap, manifestExcludeSet);

    }



    /**

     * Estimate how much data in bytes a full backup will deliver. This is used during the preflight

     * check to make sure the size doesn't exceed the backup quota.

     *

     * <p>By default, the backup size is measured by calling {@link

     * #onFullBackup(FullBackupDataOutput)} and looking at the size of the backup it produces while

     * discarding the data. This method can be overridden to provide an alternative, more efficient

     * estimation if necessary.

     *

     * @param quotaBytes The maximum data size that the transport currently permits this application

     *     to store as a backup.

     * @param transportFlags flags with additional information about the backup transport.

     * @return estimated size of the full backup. If the returned size is negative, the backup agent

     *     will fallback to using {@link #onFullBackup(FullBackupDataOutput)} to measure the size.

     */

    @FlaggedApi(Flags.FLAG_ENABLE_CROSS_PLATFORM_TRANSFER)

    public long onMeasureFullBackup(long quotaBytes, int transportFlags) throws IOException {

        return -1;

    }



    /**

     * Notification that the application's current backup operation causes it to exceed the maximum

     * size permitted by the transport. The ongoing backup operation is halted and rolled back: any
@@ -1336,6 +1356,7 @@ public abstract class BackupAgent extends ContextWrapper { 


        public void doMeasureFullBackup(

                long quotaBytes, int token, IBackupManager callbackBinder, int transportFlags) {

            long estimatedBackupSize = -1;

            FullBackupDataOutput measureOutput =

                    new FullBackupDataOutput(quotaBytes, transportFlags);
@@ -1344,7 +1365,15 @@ public abstract class BackupAgent extends ContextWrapper { 
            // Ensure that we're running with the app's normal permission level

            final long ident = Binder.clearCallingIdentity();

            try {

                if (Flags.enableCrossPlatformTransfer()) {

                    estimatedBackupSize =

                            BackupAgent.this.onMeasureFullBackup(quotaBytes, transportFlags);

                    if (estimatedBackupSize < 0) {

                        BackupAgent.this.onFullBackup(measureOutput);

                    }

                } else {

                    BackupAgent.this.onFullBackup(measureOutput);

                }

            } catch (IOException ex) {

                Log.d(

                        TAG,
@@ -1361,7 +1390,11 @@ public abstract class BackupAgent extends ContextWrapper { 
                Binder.restoreCallingIdentity(ident);

                try {

                    callbackBinder.opCompleteForUser(

                            getBackupUserId(), token, measureOutput.getSize());

                            getBackupUserId(),

                            token,

                            estimatedBackupSize >= 0

                                    ? estimatedBackupSize

                                    : measureOutput.getSize());

                } catch (RemoteException e) {

                    // timeout, so we're safe

                }

core/tests/coretests/src/android/app/backup/BackupAgentTest.java

+85 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ package android.app.backup; 


import static com.google.common.truth.Truth.assertThat;



import static org.mockito.Mockito.verify;

import static org.mockito.Mockito.when;



import android.app.IBackupAgent;
@@ -28,6 +29,8 @@ import android.app.backup.FullBackup.BackupScheme.PathWithRequiredFlags; 
import android.content.Context;

import android.os.ParcelFileDescriptor;

import android.os.UserHandle;

import android.platform.test.annotations.DisableFlags;

import android.platform.test.annotations.EnableFlags;

import android.platform.test.annotations.Presubmit;

import android.platform.test.flag.junit.SetFlagsRule;

import android.util.ArraySet;
@@ -179,6 +182,53 @@ public class BackupAgentTest { 
        }

    }



    @Test

    @DisableFlags({Flags.FLAG_ENABLE_CROSS_PLATFORM_TRANSFER})

    public void doMeasureFullBackup_flagOff_callOnFullBackup() throws Exception {

        TestMeasureSizeBackupAgent agent = new TestMeasureSizeBackupAgent(1024);

        agent.attach(mContext);

        agent.onCreate(USER_HANDLE, BackupDestination.CLOUD, OperationType.BACKUP);

        IBackupAgent agentBinder = (IBackupAgent) agent.onBind();



        agentBinder.doMeasureFullBackup(

                /* quotaBytes= */ 2048, /* token= */ 0, mIBackupManager, /* transportFlags= */ 0);



        assertThat(agent.mOnMeasureFullBackupCalled).isFalse();

        assertThat(agent.mOnFullBackupCalled).isTrue();

        verify(mIBackupManager).opCompleteForUser(USER_HANDLE.getIdentifier(), 0, 0);

    }



    @Test

    @EnableFlags({Flags.FLAG_ENABLE_CROSS_PLATFORM_TRANSFER})

    public void doMeasureFullBackup_flagOn_callsOnMeasureFullBackup() throws Exception {

        TestMeasureSizeBackupAgent agent = new TestMeasureSizeBackupAgent(1024);

        agent.attach(mContext);

        agent.onCreate(USER_HANDLE, BackupDestination.CLOUD, OperationType.BACKUP);

        IBackupAgent agentBinder = (IBackupAgent) agent.onBind();



        agentBinder.doMeasureFullBackup(

                /* quotaBytes= */ 2048, /* token= */ 0, mIBackupManager, /* transportFlags= */ 0);



        assertThat(agent.mOnMeasureFullBackupCalled).isTrue();

        assertThat(agent.mOnFullBackupCalled).isFalse();

        verify(mIBackupManager).opCompleteForUser(USER_HANDLE.getIdentifier(), 0, 1024);

    }



    @Test

    public void doMeasureFullBackup_flagOn_negativeSize_callsOnFullBackup() throws Exception {

        TestMeasureSizeBackupAgent agent = new TestMeasureSizeBackupAgent(-1);

        agent.attach(mContext);

        agent.onCreate(USER_HANDLE, BackupDestination.CLOUD, OperationType.BACKUP);

        IBackupAgent agentBinder = (IBackupAgent) agent.onBind();



        agentBinder.doMeasureFullBackup(

                /* quotaBytes= */ 2048, /* token= */ 0, mIBackupManager, /* transportFlags= */ 0);



        assertThat(agent.mOnMeasureFullBackupCalled).isTrue();

        assertThat(agent.mOnFullBackupCalled).isTrue();

        verify(mIBackupManager).opCompleteForUser(USER_HANDLE.getIdentifier(), 0, 0);

    }



    private BackupAgent getAgentForBackupDestination(@BackupDestination int backupDestination) {

        BackupAgent agent = new TestFullBackupAgent();

        agent.onCreate(USER_HANDLE, backupDestination);
@@ -221,4 +271,39 @@ public class BackupAgentTest { 
            // Ignore the file and don't consume any data.

        }

    }



    private static class TestMeasureSizeBackupAgent extends BackupAgent {

        private final long mSize;

        private boolean mOnFullBackupCalled;

        private boolean mOnMeasureFullBackupCalled;



        TestMeasureSizeBackupAgent(long size) {

            this.mSize = size;

        }



        @Override

        public void onBackup(

                ParcelFileDescriptor oldState,

                BackupDataOutput data,

                ParcelFileDescriptor newState) {

            // Left empty as this is a full backup agent.

        }



        @Override

        public void onRestore(

                BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState) {

            // Left empty as this is a full backup agent.

        }



        @Override

        public void onFullBackup(FullBackupDataOutput data) {

            mOnFullBackupCalled = true;

        }



        @Override

        public long onMeasureFullBackup(long quotaBytes, int transportFlags) {

            mOnMeasureFullBackupCalled = true;

            return mSize;

        }

    }

}

services/robotests/backup/src/android/app/backup/ForwardingBackupAgent.java

+5 −0
Original line number Diff line number Diff line
@@ -76,6 +76,11 @@ public class ForwardingBackupAgent extends BackupAgent { 
        mBackupAgent.onFullBackup(data);

    }



    @Override

    public long onMeasureFullBackup(long quotaBytes, int transportFlags) throws IOException {

        return mBackupAgent.onMeasureFullBackup(quotaBytes, transportFlags);

    }



    @Override

    public void onQuotaExceeded(long backupDataBytes, long quotaBytes) {

        mBackupAgent.onQuotaExceeded(backupDataBytes, quotaBytes);