Docks synced marker (#15)

* add docks_synced metadata info to determine how much documents were synced

* removed redundant empty lines

* remove empty line

debezium-connector-mongodb/src/main/java/io/debezium/connector/mongodb/RecordMakers.java

@@ -135,6 +135,25 @@ public CollectionId collectionId() {
             return collectionId;
         }
 
+        /**
+         * Generate and record one or more source records to describe the given object.
+         *
+         * @param id the identifier of the collection in which the document exists; may not be null
+         * @param object the document; may not be null
+         * @param timestamp the timestamp at which this operation is occurring
+         * @param docsSynced number of documents synced
+         * @return the number of source records that were generated; will be 0 or more
+         * @throws InterruptedException if the calling thread was interrupted while waiting to submit a record to
+         *             the blocking consumer
+         */
+        public int recordObject(CollectionId id, Document object, long timestamp, long docsSynced) throws InterruptedException {
+            final Struct sourceValue = source.lastOffsetStruct(replicaSetName, id, docsSynced);
+            final Map<String, ?> offset = source.lastOffset(replicaSetName);
+            String objId = idObjToJson(object);
+            assert objId != null;
+            return createRecords(sourceValue, offset, Operation.READ, objId, object, timestamp);
+        }
+
         /**
          * Generate and record one or more source records to describe the given object.
          *

debezium-connector-mongodb/src/main/java/io/debezium/connector/mongodb/Replicator.java

@@ -371,10 +371,12 @@ protected long copyCollection(MongoClient primary, CollectionId collectionId, lo
         MongoCollection<Document> docCollection = db.getCollection(collectionId.name());
         long counter = 0;
         try (MongoCursor<Document> cursor = docCollection.find().iterator()) {
-            while (running.get() && cursor.hasNext()) {
+            boolean hasNext = cursor.hasNext();
+            while (running.get() && hasNext) {
                 Document doc = cursor.next();
                 logger.trace("Found existing doc in {}: {}", collectionId, doc);
-                counter += factory.recordObject(collectionId, doc, timestamp);
+                hasNext = cursor.hasNext();
+                counter += factory.recordObject(collectionId, doc, timestamp, !hasNext ? counter+1 : -1);
             }
         }
         return counter;

debezium-connector-mongodb/src/main/java/io/debezium/connector/mongodb/SourceInfo.java

@@ -77,6 +77,7 @@ public final class SourceInfo extends AbstractSourceInfo {
     public static final String ORDER = "ord";
     public static final String OPERATION_ID = "h";
     public static final String INITIAL_SYNC = "initsync";
+    public static final String DOCS_SYNCED = "docs_synced";
 
     private static final BsonTimestamp INITIAL_TIMESTAMP = new BsonTimestamp();
     private static final Position INITIAL_POSITION = new Position(INITIAL_TIMESTAMP, null);
@@ -95,6 +96,7 @@ public final class SourceInfo extends AbstractSourceInfo {
                                                       .field(ORDER, Schema.INT32_SCHEMA)
                                                       .field(OPERATION_ID, Schema.OPTIONAL_INT64_SCHEMA)
                                                       .field(INITIAL_SYNC, SchemaBuilder.bool().optional().defaultValue(false).build())
+                                                      .field(DOCS_SYNCED, Schema.OPTIONAL_INT64_SCHEMA)
                                                       .build();
 
     private final ConcurrentMap<String, Map<String, String>> sourcePartitionsByReplicaSetName = new ConcurrentHashMap<>();
@@ -221,7 +223,22 @@ public BsonTimestamp lastOffsetTimestamp(String replicaSetName) {
      */
     public Struct lastOffsetStruct(String replicaSetName, CollectionId collectionId) {
         return offsetStructFor(replicaSetName, collectionId.namespace(), positionsByReplicaSetName.get(replicaSetName),
-                               isInitialSyncOngoing(replicaSetName));
+                               isInitialSyncOngoing(replicaSetName), -1);
+    }
+
+    /**
+     * Get a {@link Struct} representation of the source {@link #partition(String) partition} and {@link #lastOffset(String)
+     * offset} information where we have last read. The Struct complies with the {@link #schema} for the MongoDB connector.
+     *
+     * @param replicaSetName the name of the replica set name for which the new offset is to be obtained; may not be null
+     * @param collectionId the event's collection identifier; may not be null
+     * @param docsSynced number of documents synced
+     * @return the source partition and offset {@link Struct}; never null
+     * @see #schema()
+     */
+    public Struct lastOffsetStruct(String replicaSetName, CollectionId collectionId, long docsSynced) {
+        return offsetStructFor(replicaSetName, collectionId.namespace(), positionsByReplicaSetName.get(replicaSetName),
+                isInitialSyncOngoing(replicaSetName), docsSynced);
     }
 
     /**
@@ -244,7 +261,7 @@ public Struct offsetStructForEvent(String replicaSetName, Document oplogEvent) {
             namespace = oplogEvent.getString("ns");
         }
         positionsByReplicaSetName.put(replicaSetName, position);
-        return offsetStructFor(replicaSetName, namespace, position, isInitialSyncOngoing(replicaSetName));
+        return offsetStructFor(replicaSetName, namespace, position, isInitialSyncOngoing(replicaSetName), -1);
     }
 
     /**
@@ -257,7 +274,7 @@ protected static BsonTimestamp extractEventTimestamp(Document oplogEvent) {
         return oplogEvent != null ? oplogEvent.get("ts", BsonTimestamp.class) : null;
     }
 
-    private Struct offsetStructFor(String replicaSetName, String namespace, Position position, boolean isInitialSync) {
+    private Struct offsetStructFor(String replicaSetName, String namespace, Position position, boolean isInitialSync, long docsSynced) {
         if (position == null) position = INITIAL_POSITION;
         Struct result = super.struct();
         result.put(SERVER_NAME, serverName);
@@ -269,6 +286,9 @@ private Struct offsetStructFor(String replicaSetName, String namespace, Position
         if (isInitialSync) {
             result.put(INITIAL_SYNC, true);
         }
+        if (docsSynced > 0) {
+            result.put(DOCS_SYNCED, docsSynced);
+        }
         return result;
     }