1 files changed, 41 insertions, 0 deletions
diff --git a/jstests/replsets/oplog_sampling.js b/jstests/replsets/oplog_sampling.js
new file mode 100644
index 00000000000..3407b1826c9
--- /dev/null
+++ b/jstests/replsets/oplog_sampling.js
@@ -0,0 +1,41 @@
+/**
+ * Ensure serverStatus reports the total time spent sampling the oplog for all storage engines that
+ * support OplogStones.
+ * @tags: [ requires_wiredtiger, requires_persistence ]
+ */
+(function() {
+"use strict";
+
+// Force oplog sampling to occur on start up for small numbers of oplog inserts.
+const replSet = new ReplSetTest(
+    {nodes: 1, nodeOptions: {setParameter: {"maxOplogTruncationPointsDuringStartup": 10}}});
+replSet.startSet();
+replSet.initiate();
+
+let coll = replSet.getPrimary().getDB("test").getCollection("testcoll");
+
+let res = replSet.getPrimary().getDB("test").serverStatus();
+assert.commandWorked(res);
+
+// Small (or empty) oplogs should be processed by scanning.
+assert.gt(res.oplogTruncation.totalTimeProcessingMicros, 0);
+assert.eq(res.oplogTruncation.processingMethod, "scanning");
+
+// Insert enough documents to force oplog sampling to occur on the following start up.
+const maxOplogDocsForScanning = 2000;
+for (let i = 0; i < maxOplogDocsForScanning + 1; i++) {
+    assert.commandWorked(coll.insert({m: 1 + i}));
+}
+
+// Restart replica set to load entries from the oplog for sampling.
+replSet.stopSet(null /* signal */, true /* forRestart */);
+replSet.startSet({restart: true});
+
+res = replSet.getPrimary().getDB("test").serverStatus();
+assert.commandWorked(res);
+
+assert.gt(res.oplogTruncation.totalTimeProcessingMicros, 0);
+assert.eq(res.oplogTruncation.processingMethod, "sampling");
+
+replSet.stopSet();
+})();