SERVER-18771 implement getMore command on mongos

1 files changed, 55 insertions, 0 deletions

diff --git a/src/mongo/db/query/find_common.cpp b/src/mongo/db/query/find_common.cpp
new file mode 100644
index 00000000000..8d6a718313e
--- /dev/null
+++ b/src/mongo/db/query/find_common.cpp
@@ -0,0 +1,55 @@
+/**
+ *    Copyright (C) 2015 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/query/find_common.h"
+
+#include "mongo/db/query/lite_parsed_query.h"
+
+namespace mongo {
+
+bool FindCommon::enoughForFirstBatch(const LiteParsedQuery& pq,
+                                     long long numDocs,
+                                     int bytesBuffered) {
+    if (!pq.getBatchSize()) {
+        // If there is no batch size, we stop generating additional results as soon as we have
+        // either 101 documents or at least 1MB of data.
+        return (bytesBuffered > 1024 * 1024) || numDocs >= LiteParsedQuery::kDefaultBatchSize;
+    }
+
+    // If there is a batch size, we add results until either satisfying this batch size or exceeding
+    // the 4MB size threshold.
+    return numDocs >= *pq.getBatchSize() || bytesBuffered > kMaxBytesToReturnToClientAtOnce;
+}
+
+bool FindCommon::enoughForGetMore(long long ntoreturn, long long numDocs, int bytesBuffered) {
+    return (ntoreturn && numDocs >= ntoreturn) || (bytesBuffered > kMaxBytesToReturnToClientAtOnce);
+}
+
+}  // namespace mongo