1 files changed, 82 insertions, 0 deletions
diff --git a/mobile/android/services/src/main/java/org/mozilla/gecko/sync/repositories/StoreTracker.java b/mobile/android/services/src/main/java/org/mozilla/gecko/sync/repositories/StoreTracker.java
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+++ b/mobile/android/services/src/main/java/org/mozilla/gecko/sync/repositories/StoreTracker.java
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.sync.repositories;
+
+import java.util.Iterator;
+
+/**
+ * Our hacky version of transactional semantics. The goal is to prevent
+ * the following situation:
+ *
+ * * AAA is not modified locally.
+ * * A modified AAA is downloaded during the storing phase. Its local
+ *   timestamp is advanced.
+ * * The direction of syncing changes, and AAA is now uploaded to the server.
+ *
+ * The following situation should still be supported:
+ *
+ * * AAA is not modified locally.
+ * * A modified AAA is downloaded and merged with the local AAA.
+ * * The merged AAA is uploaded to the server.
+ *
+ * As should:
+ *
+ * * AAA is modified locally.
+ * * A modified AAA is downloaded, and discarded or merged.
+ * * The current version of AAA is uploaded to the server.
+ *
+ * We achieve this by tracking GUIDs during the storing phase. If we
+ * apply a record such that the local copy is substantially the same
+ * as the record we just downloaded, we add it to a list of records
+ * to avoid uploading. The definition of "substantially the same"
+ * depends on the particular repository. The only consideration is "do we
+ * want to upload this record in this sync?".
+ *
+ * Note that items are removed from this list when a fetch that
+ * considers them for upload completes successfully. The entire list
+ * is discarded when the session is completed.
+ *
+ * This interface exposes methods to:
+ *
+ * * During a store, recording that a record has been stored, and should
+ *   thus not be returned in subsequent fetches;
+ * * During a fetch, checking whether a record should be returned.
+ *
+ * In the future this might also grow self-persistence.
+ *
+ * See also RepositorySession.trackRecord.
+ *
+ * @author rnewman
+ *
+ */
+public interface StoreTracker {
+
+  /**
+   * @param guid
+   *        The GUID of the item to track.
+   * @return
+   *        Whether the GUID was a newly tracked value.
+   */
+  public boolean trackRecordForExclusion(String guid);
+
+  /**
+   * @param guid
+   *        The GUID of the item to check.
+   * @return
+   *        true if the item is already tracked.
+   */
+  public boolean isTrackedForExclusion(String guid);
+
+  /**
+  *
+  * @param guid
+  * @return true if the specified GUID was removed from the tracked set.
+  */
+  public boolean untrackStoredForExclusion(String guid);
+
+  public RecordFilter getFilter();
+
+  public Iterator<String> recordsTrackedForExclusion();
+}