SERVER-70369 add server parameter for num inserter/fetcher threads in chunk migration

(cherry picked from commit 887a6878ad584a9fcc54087112a4a2b4d39bb32e)

2 files changed, 69 insertions, 1 deletions

diff --git a/src/mongo/db/s/sharding_runtime_d_params.h b/src/mongo/db/s/sharding_runtime_d_params.h
new file mode 100644
index 00000000000..190e442a5fb
--- /dev/null
+++ b/src/mongo/db/s/sharding_runtime_d_params.h
@@ -0,0 +1,55 @@
+/**
+ *    Copyright (C) 2022-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    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
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    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 Server Side 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.
+ */
+
+#pragma once
+
+#include "fmt/core.h"
+#include "mongo/base/status.h"
+#include "mongo/s/sharding_feature_flags_gen.h"
+#include "mongo/util/processinfo.h"
+
+namespace mongo {
+
+inline Status validateMigrationConcurrency(const int& migrationConcurrency) {
+    if (!mongo::feature_flags::gConcurrencyInChunkMigration.isEnabledAndIgnoreFCV()) {
+        return Status{ErrorCodes::InvalidOptions,
+                      "Cannot set migration concurrency number without enabling migration "
+                      "concurrency feature flag"};
+    }
+    int maxConcurrency = ProcessInfo::getNumCores();
+    if (migrationConcurrency <= 0 || migrationConcurrency > maxConcurrency) {
+        return Status{
+            ErrorCodes::InvalidOptions,
+            fmt::format(
+                "Migration concurrency level must be positive and less than the number of cores.")};
+    }
+    return Status::OK();
+}
+
+}  // namespace mongo
diff --git a/src/mongo/db/s/sharding_runtime_d_params.idl b/src/mongo/db/s/sharding_runtime_d_params.idl
index aeb0c8b676a..271e2cf6882 100644
--- a/src/mongo/db/s/sharding_runtime_d_params.idl
+++ b/src/mongo/db/s/sharding_runtime_d_params.idl
@@ -27,8 +27,21 @@
 
 global:
     cpp_namespace: mongo
+    cpp_includes:
+      - "mongo/db/s/sharding_runtime_d_params.h"
 
 server_parameters:
+    migrationConcurrency:
+        description: >-
+          The number of threads doing insertions on the recipient during a chunk migration and
+          also the number of _migrateClone requests that the recipient sends to the source in parallel.
+        set_at: [startup, runtime]
+        cpp_vartype: AtomicWord<int>
+        cpp_varname: migrationConcurrency
+        validator:
+          callback: validateMigrationConcurrency
+        default: 1
+
     rangeDeleterBatchSize:
         description: >-
           The maximum number of documents in each batch to delete during the cleanup stage of chunk
@@ -57,7 +70,7 @@ server_parameters:
 
     receiveChunkWaitForRangeDeleterTimeoutMS:
         description: >-
-          Amount of time in milliseconds an incoming migration will wait for an intersecting range 
+          Amount of time in milliseconds an incoming migration will wait for an intersecting range
           with data in it to be cleared up before failing.
         set_at: [startup, runtime]
         cpp_vartype: AtomicWord<int>