SERVER-40258 Relax locking requirements for sharding metadata refresh on shards

(cherry picked from commit 0d07bf5e7a72a5bce3f7d7d681a71d7ecfe7eb8c)

3 files changed, 12 insertions, 9 deletions

diff --git a/src/mongo/db/pipeline/pipeline_d.cpp b/src/mongo/db/pipeline/pipeline_d.cpp
index 96047148104..4a4f4b7ea14 100644
--- a/src/mongo/db/pipeline/pipeline_d.cpp
+++ b/src/mongo/db/pipeline/pipeline_d.cpp
@@ -126,16 +126,13 @@ StatusWith<unique_ptr<PlanExecutor, PlanExecutor::Deleter>> createRandomCursorEx
 
     // If the incoming operation is sharded, use the CSS to infer the filtering metadata for the
     // collection, otherwise treat it as unsharded
-    boost::optional<ScopedCollectionMetadata> shardMetadata =
-        (OperationShardingState::isOperationVersioned(opCtx)
-             ? CollectionShardingState::get(opCtx, coll->ns())->getOrphansFilter(opCtx)
-             : boost::optional<ScopedCollectionMetadata>{});
+    auto shardMetadata = CollectionShardingState::get(opCtx, coll->ns())->getOrphansFilter(opCtx);
 
     // Because 'numRecords' includes orphan documents, our initial decision to optimize the $sample
     // cursor may have been mistaken. For sharded collections, build a TRIAL plan that will switch
     // to a collection scan if the ratio of orphaned to owned documents encountered over the first
     // 100 works() is such that we would have chosen not to optimize.
-    if (shardMetadata && (*shardMetadata)->isSharded()) {
+    if (shardMetadata->isSharded()) {
         // The ratio of owned to orphaned documents must be at least equal to the ratio between the
         // requested sampleSize and the maximum permitted sampleSize for the original constraints to
         // be satisfied. For instance, if there are 200 documents and the sampleSize is 5, then at
@@ -146,12 +143,12 @@ StatusWith<unique_ptr<PlanExecutor, PlanExecutor::Deleter>> createRandomCursorEx
             sampleSize / (numRecords * kMaxSampleRatioForRandCursor), kMaxSampleRatioForRandCursor);
         // The trial plan is SHARDING_FILTER-MULTI_ITERATOR.
         auto randomCursorPlan =
-            std::make_unique<ShardFilterStage>(opCtx, *shardMetadata, ws.get(), root.release());
+            std::make_unique<ShardFilterStage>(opCtx, shardMetadata, ws.get(), root.release());
         // The backup plan is SHARDING_FILTER-COLLSCAN.
         std::unique_ptr<PlanStage> collScanPlan = std::make_unique<CollectionScan>(
             opCtx, coll, CollectionScanParams{}, ws.get(), nullptr);
         collScanPlan = std::make_unique<ShardFilterStage>(
-            opCtx, *shardMetadata, ws.get(), collScanPlan.release());
+            opCtx, shardMetadata, ws.get(), collScanPlan.release());
         // Place a TRIAL stage at the root of the plan tree, and pass it the trial and backup plans.
         root = std::make_unique<TrialStage>(opCtx,
                                             ws.get(),
diff --git a/src/mongo/db/pipeline/process_interface_shardsvr.cpp b/src/mongo/db/pipeline/process_interface_shardsvr.cpp
index c2672dcf2a0..74508c4a10e 100644
--- a/src/mongo/db/pipeline/process_interface_shardsvr.cpp
+++ b/src/mongo/db/pipeline/process_interface_shardsvr.cpp
@@ -206,8 +206,9 @@ unique_ptr<Pipeline, PipelineDeleter> MongoInterfaceShardServer::attachCursorSou
 
 std::unique_ptr<ShardFilterer> MongoInterfaceShardServer::getShardFilterer(
     const boost::intrusive_ptr<ExpressionContext>& expCtx) const {
-    return std::make_unique<ShardFiltererImpl>(
-        CollectionShardingState::get(expCtx->opCtx, expCtx->ns)->getOrphansFilter(expCtx->opCtx));
+    auto shardingMetadata =
+        CollectionShardingState::get(expCtx->opCtx, expCtx->ns)->getOrphansFilter(expCtx->opCtx);
+    return std::make_unique<ShardFiltererImpl>(std::move(shardingMetadata));
 }
 
 }  // namespace mongo
diff --git a/src/mongo/db/pipeline/process_interface_standalone.h b/src/mongo/db/pipeline/process_interface_standalone.h
index 8b9df872966..ecdb5a2c0d1 100644
--- a/src/mongo/db/pipeline/process_interface_standalone.h
+++ b/src/mongo/db/pipeline/process_interface_standalone.h
@@ -57,6 +57,11 @@ public:
     DBClientBase* directClient() final;
     std::unique_ptr<TransactionHistoryIteratorBase> createTransactionHistoryIterator(
         repl::OpTime time) const final;
+
+    /**
+     * Note: Information returned can be stale. Caller should always attach shardVersion when
+     * sending request against nss based on this information.
+     */
     bool isSharded(OperationContext* opCtx, const NamespaceString& nss) final;
     Status insert(const boost::intrusive_ptr<ExpressionContext>& expCtx,
                   const NamespaceString& ns,