The Tor Browser / file diff

     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/mobile/android/base/sync/repositories/StoreTracker.java	Wed Dec 31 06:09:35 2014 +0100
     1.3 @@ -0,0 +1,82 @@
     1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
     1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
     1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
     1.7 +
     1.8 +package org.mozilla.gecko.sync.repositories;
     1.9 +
    1.10 +import java.util.Iterator;
    1.11 +
    1.12 +/**
    1.13 + * Our hacky version of transactional semantics. The goal is to prevent
    1.14 + * the following situation:
    1.15 + *
    1.16 + * * AAA is not modified locally.
    1.17 + * * A modified AAA is downloaded during the storing phase. Its local
    1.18 + *   timestamp is advanced.
    1.19 + * * The direction of syncing changes, and AAA is now uploaded to the server.
    1.20 + *
    1.21 + * The following situation should still be supported:
    1.22 + *
    1.23 + * * AAA is not modified locally.
    1.24 + * * A modified AAA is downloaded and merged with the local AAA.
    1.25 + * * The merged AAA is uploaded to the server.
    1.26 + *
    1.27 + * As should:
    1.28 + *
    1.29 + * * AAA is modified locally.
    1.30 + * * A modified AAA is downloaded, and discarded or merged.
    1.31 + * * The current version of AAA is uploaded to the server.
    1.32 + *
    1.33 + * We achieve this by tracking GUIDs during the storing phase. If we
    1.34 + * apply a record such that the local copy is substantially the same
    1.35 + * as the record we just downloaded, we add it to a list of records
    1.36 + * to avoid uploading. The definition of "substantially the same"
    1.37 + * depends on the particular repository. The only consideration is "do we
    1.38 + * want to upload this record in this sync?".
    1.39 + *
    1.40 + * Note that items are removed from this list when a fetch that
    1.41 + * considers them for upload completes successfully. The entire list
    1.42 + * is discarded when the session is completed.
    1.43 + *
    1.44 + * This interface exposes methods to:
    1.45 + *
    1.46 + * * During a store, recording that a record has been stored, and should
    1.47 + *   thus not be returned in subsequent fetches;
    1.48 + * * During a fetch, checking whether a record should be returned.
    1.49 + *
    1.50 + * In the future this might also grow self-persistence.
    1.51 + *
    1.52 + * See also RepositorySession.trackRecord.
    1.53 + *
    1.54 + * @author rnewman
    1.55 + *
    1.56 + */
    1.57 +public interface StoreTracker {
    1.58 +
    1.59 +  /**
    1.60 +   * @param guid
    1.61 +   *        The GUID of the item to track.
    1.62 +   * @return
    1.63 +   *        Whether the GUID was a newly tracked value.
    1.64 +   */
    1.65 +  public boolean trackRecordForExclusion(String guid);
    1.66 +
    1.67 +  /**
    1.68 +   * @param guid
    1.69 +   *        The GUID of the item to check.
    1.70 +   * @return
    1.71 +   *        true if the item is already tracked.
    1.72 +   */
    1.73 +  public boolean isTrackedForExclusion(String guid);
    1.74 +
    1.75 +  /**
    1.76 +  *
    1.77 +  * @param guid
    1.78 +  * @return true if the specified GUID was removed from the tracked set.
    1.79 +  */
    1.80 +  public boolean untrackStoredForExclusion(String guid);
    1.81 +
    1.82 +  public RecordFilter getFilter();
    1.83 +
    1.84 +  public Iterator<String> recordsTrackedForExclusion();
    1.85 +}