From e83005b5d44e2bcc0f7a680415fe0b2bc5582e33 Mon Sep 17 00:00:00 2001
From: adelinexchen <100674217+adelinexchen@users.noreply.github.com>
Date: Thu, 24 Jul 2025 13:14:58 +1000
Subject: [PATCH] SERVER-106210 add server parameter to turn on async oplog
 (#38510)

GitOrigin-RevId: 0a4a835d3955a6c7e6d903a516bfc2a66fbdafcb
---
 src/mongo/db/storage/oplog_truncate_marker_parameters.idl | 8 ++++++++
 src/mongo/db/storage/oplog_truncate_markers.cpp           | 7 ++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/mongo/db/storage/oplog_truncate_marker_parameters.idl b/src/mongo/db/storage/oplog_truncate_marker_parameters.idl
index 0d6d3ef9f81..9412b931f09 100644
--- a/src/mongo/db/storage/oplog_truncate_marker_parameters.idl
+++ b/src/mongo/db/storage/oplog_truncate_marker_parameters.idl
@@ -73,3 +73,11 @@ server_parameters:
         default: 300
         validator: {gt: 300}
         redact: false
+
+    oplogSamplingAsyncEnabled:
+        description: "Whether or not oplog sampling is running asynchronously to startup."
+        set_at: [startup]
+        cpp_vartype: "bool"
+        cpp_varname: gOplogSamplingAsyncEnabled
+        default: true
+        redact: false
diff --git a/src/mongo/db/storage/oplog_truncate_markers.cpp b/src/mongo/db/storage/oplog_truncate_markers.cpp
index f97045097c1..e5f6aa493a3 100644
--- a/src/mongo/db/storage/oplog_truncate_markers.cpp
+++ b/src/mongo/db/storage/oplog_truncate_markers.cpp
@@ -117,7 +117,12 @@ std::shared_ptr<OplogTruncateMarkers> OplogTruncateMarkers::sampleAndUpdate(Oper
 
 std::shared_ptr<OplogTruncateMarkers> OplogTruncateMarkers::createOplogTruncateMarkers(
     OperationContext* opCtx, RecordStore& rs) {
-    if (!feature_flags::gOplogSamplingAsyncEnabled.isEnabled()) {
+    bool samplingAsynchronously =
+        feature_flags::gOplogSamplingAsyncEnabled.isEnabled() && gOplogSamplingAsyncEnabled;
+    LOGV2(10621000,
+          "Creating oplog markers",
+          "sampling asynchronously"_attr = samplingAsynchronously);
+    if (!samplingAsynchronously) {
         return sampleAndUpdate(opCtx, rs);
     }
     return createEmptyOplogTruncateMarkers(rs);