/**
* Returns an iterator over the next batch of records for the query and updates the cursor to
* get the next batch as needed. Query has specified limit and offset from InputSplit.
*/
private Iterator<EntityResult> getIteratorAndMoveCursor() throws DatastoreException {
Query.Builder query = source.query.toBuilder().clone();
query.setLimit(Math.min(userLimit, QUERY_BATCH_LIMIT));
if (currentBatch != null && currentBatch.hasEndCursor()) {
query.setStartCursor(currentBatch.getEndCursor());
}
RunQueryRequest request = source.makeRequest(query.build());
RunQueryResponse response = datastore.runQuery(request);
currentBatch = response.getBatch();
// MORE_RESULTS_AFTER_LIMIT is not implemented yet:
// https://groups.google.com/forum/#!topic/gcd-discuss/iNs6M1jA2Vw, so
// use result count to determine if more results might exist.
int numFetch = currentBatch.getEntityResultCount();
if (source.query.hasLimit()) {
verify(
userLimit >= numFetch,
"Expected userLimit %s >= numFetch %s, because query limit %s should be <= userLimit",
userLimit,
numFetch,
query.getLimit());
userLimit -= numFetch;
}
moreResults =
// User-limit does not exist (so userLimit == MAX_VALUE) and/or has not been satisfied.
(userLimit > 0)
// All indications from the API are that there are/may be more results.
&& ((numFetch == QUERY_BATCH_LIMIT)
|| (currentBatch.getMoreResults() == NOT_FINISHED));
// May receive a batch of 0 results if the number of records is a multiple
// of the request limit.
if (numFetch == 0) {
return null;
}
return currentBatch.getEntityResultList().iterator();
}
