xref: /packages/apps/Exchange/src/com/android/exchange/adapter/EmailSyncAdapter.java

/*
 * Copyright (C) 2008-2009 Marc Blank
 * Licensed to 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.exchange.adapter;

import com.android.email.mail.Address;
import com.android.email.provider.EmailContent;
import com.android.email.provider.EmailProvider;
import com.android.email.provider.EmailContent.Account;
import com.android.email.provider.EmailContent.AccountColumns;
import com.android.email.provider.EmailContent.Attachment;
import com.android.email.provider.EmailContent.Mailbox;
import com.android.email.provider.EmailContent.Message;
import com.android.email.provider.EmailContent.MessageColumns;
import com.android.email.provider.EmailContent.SyncColumns;
import com.android.email.service.MailService;
import com.android.exchange.Eas;
import com.android.exchange.EasSyncService;

import android.content.ContentProviderOperation;
import android.content.ContentResolver;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.OperationApplicationException;
import android.database.Cursor;
import android.net.Uri;
import android.os.RemoteException;
import android.webkit.MimeTypeMap;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.TimeZone;

/**
 * Sync adapter for EAS email
 *
 */
public class EmailSyncAdapter extends AbstractSyncAdapter {

    private static final int UPDATES_READ_COLUMN = 0;
    private static final int UPDATES_MAILBOX_KEY_COLUMN = 1;
    private static final int UPDATES_SERVER_ID_COLUMN = 2;
    private static final int UPDATES_FLAG_COLUMN = 3;
    private static final String[] UPDATES_PROJECTION =
        {MessageColumns.FLAG_READ, MessageColumns.MAILBOX_KEY, SyncColumns.SERVER_ID,
            MessageColumns.FLAG_FAVORITE};

    String[] bindArguments = new String[2];

    ArrayList<Long> mDeletedIdList = new ArrayList<Long>();
    ArrayList<Long> mUpdatedIdList = new ArrayList<Long>();

    public EmailSyncAdapter(Mailbox mailbox, EasSyncService service) {
        super(mailbox, service);
    }

    @Override
    public boolean parse(InputStream is) throws IOException {
        EasEmailSyncParser p = new EasEmailSyncParser(is, this);
        return p.parse();
    }

    public class EasEmailSyncParser extends AbstractSyncParser {

        private static final String WHERE_SERVER_ID_AND_MAILBOX_KEY =
            SyncColumns.SERVER_ID + "=? and " + MessageColumns.MAILBOX_KEY + "=?";

        private String mMailboxIdAsString;

        ArrayList<Message> newEmails = new ArrayList<Message>();
        ArrayList<Long> deletedEmails = new ArrayList<Long>();
        ArrayList<ServerChange> changedEmails = new ArrayList<ServerChange>();

        public EasEmailSyncParser(InputStream in, EmailSyncAdapter adapter) throws IOException {
            super(in, adapter);
            mMailboxIdAsString = Long.toString(mMailbox.mId);
        }

        @Override
        public void wipe() {
            mContentResolver.delete(Message.CONTENT_URI,
                    Message.MAILBOX_KEY + "=" + mMailbox.mId, null);
            mContentResolver.delete(Message.DELETED_CONTENT_URI,
                    Message.MAILBOX_KEY + "=" + mMailbox.mId, null);
            mContentResolver.delete(Message.UPDATED_CONTENT_URI,
                    Message.MAILBOX_KEY + "=" + mMailbox.mId, null);
        }

        public void addData (Message msg) throws IOException {
            ArrayList<Attachment> atts = new ArrayList<Attachment>();

            while (nextTag(Tags.SYNC_APPLICATION_DATA) != END) {
                switch (tag) {
                    case Tags.EMAIL_ATTACHMENTS:
                    case Tags.BASE_ATTACHMENTS: // BASE_ATTACHMENTS is used in EAS 12.0 and up
                        attachmentsParser(atts, msg);
                        break;
                    case Tags.EMAIL_TO:
                        msg.mTo = Address.pack(Address.parse(getValue()));
                        break;
                    case Tags.EMAIL_FROM:
                        Address[] froms = Address.parse(getValue());
                        if (froms != null && froms.length > 0) {
                          msg.mDisplayName = froms[0].toFriendly();
                        }
                        msg.mFrom = Address.pack(froms);
                        break;
                    case Tags.EMAIL_CC:
                        msg.mCc = Address.pack(Address.parse(getValue()));
                        break;
                    case Tags.EMAIL_REPLY_TO:
                        msg.mReplyTo = Address.pack(Address.parse(getValue()));
                        break;
                    case Tags.EMAIL_DATE_RECEIVED:
                        String date = getValue();
                        // 2009-02-11T18:03:03.627Z
                        GregorianCalendar cal = new GregorianCalendar();
                        cal.set(Integer.parseInt(date.substring(0, 4)), Integer.parseInt(date
                                .substring(5, 7)) - 1, Integer.parseInt(date.substring(8, 10)),
                                Integer.parseInt(date.substring(11, 13)), Integer.parseInt(date
                                        .substring(14, 16)), Integer.parseInt(date
                                                .substring(17, 19)));
                        cal.setTimeZone(TimeZone.getTimeZone("GMT"));
                        msg.mTimeStamp = cal.getTimeInMillis();
                        break;
                    case Tags.EMAIL_SUBJECT:
                        msg.mSubject = getValue();
                        break;
                    case Tags.EMAIL_READ:
                        msg.mFlagRead = getValueInt() == 1;
                        break;
                    case Tags.BASE_BODY:
                        bodyParser(msg);
                        break;
                    case Tags.EMAIL_FLAG:
                        msg.mFlagFavorite = flagParser();
                        break;
                    case Tags.EMAIL_BODY:
                        String text = getValue();
                        msg.mText = text;
                        break;
                    default:
                        skipTag();
                }
            }

            if (atts.size() > 0) {
                msg.mAttachments = atts;
            }
        }

        private void addParser(ArrayList<Message> emails) throws IOException {
            Message msg = new Message();
            msg.mAccountKey = mAccount.mId;
            msg.mMailboxKey = mMailbox.mId;
            msg.mFlagLoaded = Message.FLAG_LOADED_COMPLETE;

            while (nextTag(Tags.SYNC_ADD) != END) {
                switch (tag) {
                    case Tags.SYNC_SERVER_ID:
                        msg.mServerId = getValue();
                        break;
                    case Tags.SYNC_APPLICATION_DATA:
                        addData(msg);
                        break;
                    default:
                        skipTag();
                }
            }
            emails.add(msg);
        }

        // For now, we only care about the "active" state
        private Boolean flagParser() throws IOException {
            Boolean state = false;
            while (nextTag(Tags.EMAIL_FLAG) != END) {
                switch (tag) {
                    case Tags.EMAIL_FLAG_STATUS:
                        state = getValueInt() == 2;
                        break;
                    default:
                        skipTag();
                }
            }
            return state;
        }

        private void bodyParser(Message msg) throws IOException {
            String bodyType = Eas.BODY_PREFERENCE_TEXT;
            String body = "";
            while (nextTag(Tags.EMAIL_BODY) != END) {
                switch (tag) {
                    case Tags.BASE_TYPE:
                        bodyType = getValue();
                        break;
                    case Tags.BASE_DATA:
                        body = getValue();
                        break;
                    default:
                        skipTag();
                }
            }
            // We always ask for TEXT or HTML; there's no third option
            if (bodyType.equals(Eas.BODY_PREFERENCE_HTML)) {
                msg.mHtml = body;
            } else {
                msg.mText = body;
            }
        }

        private void attachmentsParser(ArrayList<Attachment> atts, Message msg) throws IOException {
            while (nextTag(Tags.EMAIL_ATTACHMENTS) != END) {
                switch (tag) {
                    case Tags.EMAIL_ATTACHMENT:
                    case Tags.BASE_ATTACHMENT:  // BASE_ATTACHMENT is used in EAS 12.0 and up
                        attachmentParser(atts, msg);
                        break;
                    default:
                        skipTag();
                }
            }
        }

        private void attachmentParser(ArrayList<Attachment> atts, Message msg) throws IOException {
            String fileName = null;
            String length = null;
            String location = null;

            while (nextTag(Tags.EMAIL_ATTACHMENT) != END) {
                switch (tag) {
                    // We handle both EAS 2.5 and 12.0+ attachments here
                    case Tags.EMAIL_DISPLAY_NAME:
                    case Tags.BASE_DISPLAY_NAME:
                        fileName = getValue();
                        break;
                    case Tags.EMAIL_ATT_NAME:
                    case Tags.BASE_FILE_REFERENCE:
                        location = getValue();
                        break;
                    case Tags.EMAIL_ATT_SIZE:
                    case Tags.BASE_ESTIMATED_DATA_SIZE:
                        length = getValue();
                        break;
                    default:
                        skipTag();
                }
            }

            if ((fileName != null) && (length != null) && (location != null)) {
                Attachment att = new Attachment();
                att.mEncoding = "base64";
                att.mSize = Long.parseLong(length);
                att.mFileName = fileName;
                att.mLocation = location;
                att.mMimeType = getMimeTypeFromFileName(fileName);
                atts.add(att);
                msg.mFlagAttachment = true;
            }
        }

        /**
         * Try to determine a mime type from a file name, defaulting to application/x, where x
         * is either the extension or (if none) octet-stream
         * At the moment, this is somewhat lame, since many file types aren't recognized
         * @param fileName the file name to ponder
         * @return
         */
        // Note: The MimeTypeMap method currently uses a very limited set of mime types
        // A bug has been filed against this issue.
        public String getMimeTypeFromFileName(String fileName) {
            String mimeType;
            int lastDot = fileName.lastIndexOf('.');
            String extension = null;
            if ((lastDot > 0) && (lastDot < fileName.length() - 1)) {
                extension = fileName.substring(lastDot + 1).toLowerCase();
            }
            if (extension == null) {
                // A reasonable default for now.
                mimeType = "application/octet-stream";
            } else {
                mimeType = MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
                if (mimeType == null) {
                    mimeType = "application/" + extension;
                }
            }
            return mimeType;
        }

        private Cursor getServerIdCursor(String serverId, String[] projection) {
            bindArguments[0] = serverId;
            bindArguments[1] = mMailboxIdAsString;
            return mContentResolver.query(Message.CONTENT_URI, projection,
                    WHERE_SERVER_ID_AND_MAILBOX_KEY, bindArguments, null);
        }

        private void deleteParser(ArrayList<Long> deletes, int entryTag) throws IOException {
            while (nextTag(entryTag) != END) {
                switch (tag) {
                    case Tags.SYNC_SERVER_ID:
                        String serverId = getValue();
                        // Find the message in this mailbox with the given serverId
                        Cursor c = getServerIdCursor(serverId, Message.ID_COLUMN_PROJECTION);
                        try {
                            if (c.moveToFirst()) {
                                userLog("Deleting ", serverId);
                                deletes.add(c.getLong(Message.ID_COLUMNS_ID_COLUMN));
                            }
                        } finally {
                            c.close();
                        }
                        break;
                    default:
                        skipTag();
                }
            }
        }

        class ServerChange {
            long id;
            Boolean read;
            Boolean flag;

            ServerChange(long _id, Boolean _read, Boolean _flag) {
                id = _id;
                read = _read;
                flag = _flag;
            }
        }

        private void changeParser(ArrayList<ServerChange> changes) throws IOException {
            String serverId = null;
            Boolean oldRead = false;
            Boolean read = null;
            Boolean oldFlag = false;
            Boolean flag = null;
            long id = 0;
            while (nextTag(Tags.SYNC_CHANGE) != END) {
                switch (tag) {
                    case Tags.SYNC_SERVER_ID:
                        serverId = getValue();
                        Cursor c = getServerIdCursor(serverId, Message.LIST_PROJECTION);
                        try {
                            if (c.moveToFirst()) {
                                userLog("Changing ", serverId);
                                oldRead = c.getInt(Message.LIST_READ_COLUMN) == Message.READ;
                                oldFlag = c.getInt(Message.LIST_FAVORITE_COLUMN) == 1;
                                id = c.getLong(Message.LIST_ID_COLUMN);
                            }
                        } finally {
                            c.close();
                        }
                        break;
                    case Tags.EMAIL_READ:
                        read = getValueInt() == 1;
                        break;
                    case Tags.EMAIL_FLAG:
                        flag = flagParser();
                        break;
                    case Tags.SYNC_APPLICATION_DATA:
                        break;
                    default:
                        skipTag();
                }
            }
            if (((read != null) && !oldRead.equals(read)) ||
                    ((flag != null) && !oldFlag.equals(flag))) {
                changes.add(new ServerChange(id, read, flag));
            }
        }

        /* (non-Javadoc)
         * @see com.android.exchange.adapter.EasContentParser#commandsParser()
         */
        @Override
        public void commandsParser() throws IOException {
            while (nextTag(Tags.SYNC_COMMANDS) != END) {
                if (tag == Tags.SYNC_ADD) {
                    addParser(newEmails);
                    incrementChangeCount();
                } else if (tag == Tags.SYNC_DELETE || tag == Tags.SYNC_SOFT_DELETE) {
                    deleteParser(deletedEmails, tag);
                    incrementChangeCount();
                } else if (tag == Tags.SYNC_CHANGE) {
                    changeParser(changedEmails);
                    incrementChangeCount();
                } else
                    skipTag();
            }
        }

        @Override
        public void responsesParser() {
        }

        @Override
        public void commit() {
            int notifyCount = 0;

            // Use a batch operation to handle the changes
            // TODO New mail notifications?  Who looks for these?
            ArrayList<ContentProviderOperation> ops = new ArrayList<ContentProviderOperation>();
            for (Message msg: newEmails) {
                if (!msg.mFlagRead) {
                    notifyCount++;
                }
                msg.addSaveOps(ops);
            }
            for (Long id : deletedEmails) {
                ops.add(ContentProviderOperation.newDelete(
                        ContentUris.withAppendedId(Message.CONTENT_URI, id)).build());
            }
            if (!changedEmails.isEmpty()) {
                // Server wins in a conflict...
                for (ServerChange change : changedEmails) {
                     ContentValues cv = new ContentValues();
                    if (change.read != null) {
                        cv.put(MessageColumns.FLAG_READ, change.read);
                    }
                    if (change.flag != null) {
                        cv.put(MessageColumns.FLAG_FAVORITE, change.flag);
                    }
                    ops.add(ContentProviderOperation.newUpdate(
                            ContentUris.withAppendedId(Message.CONTENT_URI, change.id))
                                .withValues(cv)
                                .build());
                }
            }
            ops.add(ContentProviderOperation.newUpdate(
                    ContentUris.withAppendedId(Mailbox.CONTENT_URI, mMailbox.mId)).withValues(
                    mMailbox.toContentValues()).build());

            addCleanupOps(ops);

            // No commits if we're stopped
            synchronized (mService.getSynchronizer()) {
                if (mService.isStopped()) return;
                try {
                    mContentResolver.applyBatch(EmailProvider.EMAIL_AUTHORITY, ops);
                    userLog(mMailbox.mDisplayName, " SyncKey saved as: ", mMailbox.mSyncKey);
                } catch (RemoteException e) {
                    // There is nothing to be done here; fail by returning null
                } catch (OperationApplicationException e) {
                    // There is nothing to be done here; fail by returning null
                }
            }

            if (notifyCount > 0) {
                // Use the new atomic add URI in EmailProvider
                // We could add this to the operations being done, but it's not strictly
                // speaking necessary, as the previous batch preserves the integrity of the
                // database, whereas this is purely for notification purposes, and is itself atomic
                ContentValues cv = new ContentValues();
                cv.put(EmailContent.FIELD_COLUMN_NAME, AccountColumns.NEW_MESSAGE_COUNT);
                cv.put(EmailContent.ADD_COLUMN_NAME, notifyCount);
                Uri uri = ContentUris.withAppendedId(Account.ADD_TO_FIELD_URI, mAccount.mId);
                mContentResolver.update(uri, cv, null, null);
                MailService.actionNotifyNewMessages(mContext, mAccount.mId);
            }
        }
    }

    @Override
    public String getCollectionName() {
        return "Email";
    }

    private void addCleanupOps(ArrayList<ContentProviderOperation> ops) {
        // If we've sent local deletions, clear out the deleted table
        for (Long id: mDeletedIdList) {
            ops.add(ContentProviderOperation.newDelete(
                    ContentUris.withAppendedId(Message.DELETED_CONTENT_URI, id)).build());
        }
        // And same with the updates
        for (Long id: mUpdatedIdList) {
            ops.add(ContentProviderOperation.newDelete(
                    ContentUris.withAppendedId(Message.UPDATED_CONTENT_URI, id)).build());
        }
    }

    @Override
    public void cleanup() {
        if (!mDeletedIdList.isEmpty() || !mUpdatedIdList.isEmpty()) {
            ArrayList<ContentProviderOperation> ops = new ArrayList<ContentProviderOperation>();
            addCleanupOps(ops);
            try {
                mContext.getContentResolver()
                    .applyBatch(EmailProvider.EMAIL_AUTHORITY, ops);
            } catch (RemoteException e) {
                // There is nothing to be done here; fail by returning null
            } catch (OperationApplicationException e) {
                // There is nothing to be done here; fail by returning null
            }
        }
    }

    private String formatTwo(int num) {
        if (num < 10) {
            return "0" + (char)('0' + num);
        } else
            return Integer.toString(num);
    }

    /**
     * Create date/time in RFC8601 format.  Oddly enough, for calendar date/time, Microsoft uses
     * a different format that excludes the punctuation (this is why I'm not putting this in a
     * parent class)
     */
    public String formatDateTime(Calendar calendar) {
        StringBuilder sb = new StringBuilder();
        //YYYY-MM-DDTHH:MM:SS.MSSZ
        sb.append(calendar.get(Calendar.YEAR));
        sb.append('-');
        sb.append(formatTwo(calendar.get(Calendar.MONTH) + 1));
        sb.append('-');
        sb.append(formatTwo(calendar.get(Calendar.DAY_OF_MONTH)));
        sb.append('T');
        sb.append(formatTwo(calendar.get(Calendar.HOUR_OF_DAY)));
        sb.append(':');
        sb.append(formatTwo(calendar.get(Calendar.MINUTE)));
        sb.append(':');
        sb.append(formatTwo(calendar.get(Calendar.SECOND)));
        sb.append(".000Z");
        return sb.toString();
    }

    @Override
    public boolean sendLocalChanges(Serializer s) throws IOException {
        ContentResolver cr = mContext.getContentResolver();

        // Never upsync from these folders
        if (mMailbox.mType == Mailbox.TYPE_DRAFTS || mMailbox.mType == Mailbox.TYPE_OUTBOX) {
            return false;
        }

        // Find any of our deleted items
        Cursor c = cr.query(Message.DELETED_CONTENT_URI, Message.LIST_PROJECTION,
                MessageColumns.MAILBOX_KEY + '=' + mMailbox.mId, null, null);
        boolean first = true;
        // We keep track of the list of deleted item id's so that we can remove them from the
        // deleted table after the server receives our command
        mDeletedIdList.clear();
        try {
            while (c.moveToNext()) {
                String serverId = c.getString(Message.LIST_SERVER_ID_COLUMN);
                // Keep going if there's no serverId
                if (serverId == null) {
                    continue;
                } else if (first) {
                    s.start(Tags.SYNC_COMMANDS);
                    first = false;
                }
                // Send the command to delete this message
                s.start(Tags.SYNC_DELETE).data(Tags.SYNC_SERVER_ID, serverId).end();
                mDeletedIdList.add(c.getLong(Message.LIST_ID_COLUMN));
            }
        } finally {
            c.close();
        }

        // Find our trash mailbox, since deletions will have been moved there...
        long trashMailboxId =
            Mailbox.findMailboxOfType(mContext, mMailbox.mAccountKey, Mailbox.TYPE_TRASH);

        // Do the same now for updated items
        c = cr.query(Message.UPDATED_CONTENT_URI, Message.LIST_PROJECTION,
                MessageColumns.MAILBOX_KEY + '=' + mMailbox.mId, null, null);

        // We keep track of the list of updated item id's as we did above with deleted items
        mUpdatedIdList.clear();
        try {
            while (c.moveToNext()) {
                long id = c.getLong(Message.LIST_ID_COLUMN);
                // Say we've handled this update
                mUpdatedIdList.add(id);
                // We have the id of the changed item.  But first, we have to find out its current
                // state, since the updated table saves the opriginal state
                Cursor currentCursor = cr.query(ContentUris.withAppendedId(Message.CONTENT_URI, id),
                        UPDATES_PROJECTION, null, null, null);
                try {
                    // If this item no longer exists (shouldn't be possible), just move along
                    if (!currentCursor.moveToFirst()) {
                         continue;
                    }
                    // Keep going if there's no serverId
                    String serverId = currentCursor.getString(UPDATES_SERVER_ID_COLUMN);
                    if (serverId == null) {
                        continue;
                    }
                    // If the message is now in the trash folder, it has been deleted by the user
                    if (currentCursor.getLong(UPDATES_MAILBOX_KEY_COLUMN) == trashMailboxId) {
                         if (first) {
                            s.start(Tags.SYNC_COMMANDS);
                            first = false;
                        }
                        // Send the command to delete this message
                        s.start(Tags.SYNC_DELETE).data(Tags.SYNC_SERVER_ID, serverId).end();
                        continue;
                    }

                    boolean flagChange = false;
                    boolean readChange = false;

                    int flag = 0;

                    // We can only send flag changes to the server in 12.0 or later
                    if (mService.mProtocolVersionDouble >= 12.0) {
                        flag = currentCursor.getInt(UPDATES_FLAG_COLUMN);
                        if (flag != c.getInt(Message.LIST_FAVORITE_COLUMN)) {
                            flagChange = true;
                        }
                    }

                    int read = currentCursor.getInt(UPDATES_READ_COLUMN);
                    if (read != c.getInt(Message.LIST_READ_COLUMN)) {
                        readChange = true;
                    }

                    if (!flagChange && !readChange) {
                        // In this case, we've got nothing to send to the server
                        continue;
                    }

                    if (first) {
                        s.start(Tags.SYNC_COMMANDS);
                        first = false;
                    }
                    // Send the change to "read" and "favorite" (flagged)
                    s.start(Tags.SYNC_CHANGE)
                        .data(Tags.SYNC_SERVER_ID, c.getString(Message.LIST_SERVER_ID_COLUMN))
                        .start(Tags.SYNC_APPLICATION_DATA);
                    if (readChange) {
                        s.data(Tags.EMAIL_READ, Integer.toString(read));
                    }
                    // "Flag" is a relatively complex concept in EAS 12.0 and above.  It is not only
                    // the boolean "favorite" that we think of in Gmail, but it also represents a
                    // follow up action, which can include a subject, start and due dates, and even
                    // recurrences.  We don't support any of this as yet, but EAS 12.0 and higher
                    // require that a flag contain a status, a type, and four date fields, two each
                    // for start date and end (due) date.
                    if (flagChange) {
                        if (flag != 0) {
                            // Status 2 = set flag
                            s.start(Tags.EMAIL_FLAG).data(Tags.EMAIL_FLAG_STATUS, "2");
                            // "FollowUp" is the standard type
                            s.data(Tags.EMAIL_FLAG_TYPE, "FollowUp");
                            long now = System.currentTimeMillis();
                            Calendar calendar =
                                GregorianCalendar.getInstance(TimeZone.getTimeZone("GMT"));
                            calendar.setTimeInMillis(now);
                            // Flags are required to have a start date and end date (duplicated)
                            // First, we'll set the current date/time in GMT as the start time
                            String utc = formatDateTime(calendar);
                            s.data(Tags.TASK_START_DATE, utc).data(Tags.TASK_UTC_START_DATE, utc);
                            // And then we'll use one week from today for completion date
                            calendar.setTimeInMillis(now + 1*WEEKS);
                            utc = formatDateTime(calendar);
                            s.data(Tags.TASK_DUE_DATE, utc).data(Tags.TASK_UTC_DUE_DATE, utc);
                            s.end();
                        } else {
                            s.tag(Tags.EMAIL_FLAG);
                        }
                    }
                    s.end().end(); // SYNC_APPLICATION_DATA, SYNC_CHANGE
                } finally {
                    currentCursor.close();
                }
            }
        } finally {
            c.close();
        }

        if (!first) {
            s.end(); // SYNC_COMMANDS
        }
        return false;
    }
}