SERVER-42737 Make secondary reads in ShardServerCatalogCacheLoader block behind the PBW lock

(cherry picked from commit e0f6fdab23da872d9cf8a93b88c2332ba45041c0)

3 files changed, 43 insertions, 0 deletions

diff --git a/src/mongo/db/db_raii.cpp b/src/mongo/db/db_raii.cpp
index fd04dac348d..2335603d380 100644
--- a/src/mongo/db/db_raii.cpp
+++ b/src/mongo/db/db_raii.cpp
@@ -46,6 +46,12 @@ namespace {
 
 const boost::optional<int> kDoNotChangeProfilingLevel = boost::none;
 
+// TODO: SERVER-44105 remove
+// If set to false, secondary reads should wait behind the PBW lock.
+// Does nothing if gAllowSecondaryReadsDuringBatchApplication setting is false.
+const auto allowSecondaryReadsDuringBatchApplication_DONT_USE =
+    OperationContext::declareDecoration<boost::optional<bool>>();
+
 }  // namespace
 
 AutoStatsTracker::AutoStatsTracker(OperationContext* opCtx,
@@ -92,6 +98,7 @@ AutoGetCollectionForRead::AutoGetCollectionForRead(OperationContext* opCtx,
     // Don't take the ParallelBatchWriterMode lock when the server parameter is set and our
     // storage engine supports snapshot reads.
     if (gAllowSecondaryReadsDuringBatchApplication.load() &&
+        allowSecondaryReadsDuringBatchApplication_DONT_USE(opCtx).value_or(true) &&
         opCtx->getServiceContext()->getStorageEngine()->supportsReadConcernSnapshot()) {
         _shouldNotConflictWithSecondaryBatchApplicationBlock.emplace(opCtx->lockState());
     }
@@ -386,4 +393,18 @@ LockMode getLockModeForQuery(OperationContext* opCtx, const boost::optional<Name
     return MODE_IS;
 }
 
+BlockSecondaryReadsDuringBatchApplication_DONT_USE::
+    BlockSecondaryReadsDuringBatchApplication_DONT_USE(OperationContext* opCtx)
+    : _opCtx(opCtx) {
+    auto allowSecondaryReads = &allowSecondaryReadsDuringBatchApplication_DONT_USE(opCtx);
+    allowSecondaryReads->swap(_originalSettings);
+    *allowSecondaryReads = false;
+}
+
+BlockSecondaryReadsDuringBatchApplication_DONT_USE::
+    ~BlockSecondaryReadsDuringBatchApplication_DONT_USE() {
+    auto allowSecondaryReads = &allowSecondaryReadsDuringBatchApplication_DONT_USE(_opCtx);
+    allowSecondaryReads->swap(_originalSettings);
+}
+
 }  // namespace mongo
diff --git a/src/mongo/db/db_raii.h b/src/mongo/db/db_raii.h
index f5497c6f3a1..940e13c1f6f 100644
--- a/src/mongo/db/db_raii.h
+++ b/src/mongo/db/db_raii.h
@@ -259,4 +259,19 @@ private:
     PrepareConflictBehavior _originalValue;
 };
 
+/**
+ * TODO: SERVER-44105 remove
+ * RAII type for letting secondary reads to block behind the PBW lock.
+ * Note: Do not add additional usage. This is only temporary for ease of backport.
+ */
+struct BlockSecondaryReadsDuringBatchApplication_DONT_USE {
+public:
+    BlockSecondaryReadsDuringBatchApplication_DONT_USE(OperationContext* opCtx);
+    ~BlockSecondaryReadsDuringBatchApplication_DONT_USE();
+
+private:
+    OperationContext* _opCtx{nullptr};
+    boost::optional<bool> _originalSettings;
+};
+
 }  // namespace mongo
diff --git a/src/mongo/db/s/shard_server_catalog_cache_loader.cpp b/src/mongo/db/s/shard_server_catalog_cache_loader.cpp
index 142b7d3e69f..dec279a747f 100644
--- a/src/mongo/db/s/shard_server_catalog_cache_loader.cpp
+++ b/src/mongo/db/s/shard_server_catalog_cache_loader.cpp
@@ -34,6 +34,7 @@
 #include "mongo/db/s/shard_server_catalog_cache_loader.h"
 
 #include "mongo/db/client.h"
+#include "mongo/db/db_raii.h"
 #include "mongo/db/operation_context.h"
 #include "mongo/db/operation_context_group.h"
 #include "mongo/db/read_concern.h"
@@ -575,6 +576,12 @@ void ShardServerCatalogCacheLoader::_runSecondaryGetChunksSince(
     forcePrimaryCollectionRefreshAndWaitForReplication(opCtx, nss);
 
     // Read the local metadata.
+
+    // Disallow reading on an older snapshot because this relies on being able to read the
+    // side effects of writes during secondary replication after being signalled from the
+    // CollectionVersionLogOpHandler.
+    BlockSecondaryReadsDuringBatchApplication_DONT_USE secondaryReadsBlockBehindReplication(opCtx);
+
     auto swCollAndChunks =
         _getCompletePersistedMetadataForSecondarySinceVersion(opCtx, nss, catalogCacheSinceVersion);
     callbackFn(opCtx, std::move(swCollAndChunks));