6 files changed, 43 insertions, 1 deletions

diff --git a/src/mongo/db/s/sharding_initialization_mongod.cpp b/src/mongo/db/s/sharding_initialization_mongod.cpp
index 8963f20de1a..325ace6d4a1 100644
--- a/src/mongo/db/s/sharding_initialization_mongod.cpp
+++ b/src/mongo/db/s/sharding_initialization_mongod.cpp
@@ -54,6 +54,7 @@
 #include "mongo/s/client/shard_remote.h"
 #include "mongo/s/client/sharding_connection_hook.h"
 #include "mongo/s/config_server_catalog_cache_loader.h"
+#include "mongo/s/grid.h"
 #include "mongo/s/sharding_initialization.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/util/log.h"
@@ -125,7 +126,7 @@ Status initializeGlobalShardingStateForMongod(OperationContext* opCtx,
     globalConnPool.addHook(new ShardingConnectionHook(false, makeEgressHooksList(service)));
     shardConnectionPool.addHook(new ShardingConnectionHook(true, makeEgressHooksList(service)));
 
-    return initializeGlobalShardingState(
+    Status initStatus = initializeGlobalShardingState(
         opCtx,
         configCS,
         distLockProcessId,
@@ -135,6 +136,12 @@ Status initializeGlobalShardingStateForMongod(OperationContext* opCtx,
         // We only need one task executor here because sharding task executors aren't used for user
         // queries in mongod.
         1);
+
+    if (initStatus.isOK()) {
+        Grid::get(opCtx)->setShardingInitialized();
+    }
+
+    return initStatus;
 }
 
 }  // namespace mongo
diff --git a/src/mongo/db/sessions_collection_config_server.cpp b/src/mongo/db/sessions_collection_config_server.cpp
index 179687e33d4..35fc8c5c837 100644
--- a/src/mongo/db/sessions_collection_config_server.cpp
+++ b/src/mongo/db/sessions_collection_config_server.cpp
@@ -91,6 +91,11 @@ Status SessionsCollectionConfigServer::_generateIndexesIfNeeded(OperationContext
 }
 
 Status SessionsCollectionConfigServer::setupSessionsCollection(OperationContext* opCtx) {
+    // If the sharding state is not yet initialized, fail.
+    if (!Grid::get(opCtx)->isShardingInitialized()) {
+        return {ErrorCodes::ShardingStateNotInitialized, "sharding state is not yet initialized"};
+    }
+
     stdx::lock_guard<stdx::mutex> lk(_mutex);
     {
         // Only try to set up this collection until we have done so successfully once.
diff --git a/src/mongo/db/sessions_collection_sharded.cpp b/src/mongo/db/sessions_collection_sharded.cpp
index a0142e2a2fd..8873f17be4b 100644
--- a/src/mongo/db/sessions_collection_sharded.cpp
+++ b/src/mongo/db/sessions_collection_sharded.cpp
@@ -56,6 +56,11 @@ BSONObj lsidQuery(const LogicalSessionId& lsid) {
 }  // namespace
 
 Status SessionsCollectionSharded::_checkCacheForSessionsCollection(OperationContext* opCtx) {
+    // If the sharding state is not yet initialized, fail.
+    if (!Grid::get(opCtx)->isShardingInitialized()) {
+        return {ErrorCodes::ShardingStateNotInitialized, "sharding state is not yet initialized"};
+    }
+
     // If the collection doesn't exist, fail. Only the config servers generate it.
     auto res = Grid::get(opCtx)->catalogCache()->getShardedCollectionRoutingInfoWithRefresh(
         opCtx, NamespaceString(SessionsCollection::kSessionsFullNS.toString()));
diff --git a/src/mongo/s/grid.cpp b/src/mongo/s/grid.cpp
index e27d34f3891..6570ca0c751 100644
--- a/src/mongo/s/grid.cpp
+++ b/src/mongo/s/grid.cpp
@@ -85,6 +85,15 @@ void Grid::init(std::unique_ptr<ShardingCatalogClient> catalogClient,
     _shardRegistry->init();
 }
 
+bool Grid::isShardingInitialized() const {
+    return _shardingInitialized.load();
+}
+
+void Grid::setShardingInitialized() {
+    invariant(!_shardingInitialized.load());
+    _shardingInitialized.store(true);
+}
+
 Grid::CustomConnectionPoolStatsFn Grid::getCustomConnectionPoolStatsFn() const {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
     return _customConnectionPoolStatsFn;
diff --git a/src/mongo/s/grid.h b/src/mongo/s/grid.h
index ba47fa07c4e..443c9b81304 100644
--- a/src/mongo/s/grid.h
+++ b/src/mongo/s/grid.h
@@ -82,6 +82,18 @@ public:
               executor::NetworkInterface* network);
 
     /**
+     * Used to check if sharding is initialized for usage of global sharding services. Protected by
+     * an atomic access guard.
+     */
+    bool isShardingInitialized() const;
+
+    /**
+     * Used to indicate the sharding initialization process is complete. Should only be called once
+     * in the lifetime of a server. Protected by an atomic access guard.
+     */
+    void setShardingInitialized();
+
+    /**
      * If the instance as which this sharding component is running (config/shard/mongos) uses
      * additional connection pools other than the default, this function will be present and can be
      * used to obtain statistics about them. Otherwise, the value will be unset.
@@ -173,6 +185,8 @@ private:
 
     CustomConnectionPoolStatsFn _customConnectionPoolStatsFn;
 
+    AtomicBool _shardingInitialized{false};
+
     // Protects _configOpTime.
     mutable stdx::mutex _mutex;
 
diff --git a/src/mongo/s/server.cpp b/src/mongo/s/server.cpp
index cedcf00ff64..b35b3ed28ab 100644
--- a/src/mongo/s/server.cpp
+++ b/src/mongo/s/server.cpp
@@ -321,6 +321,8 @@ Status initializeSharding(OperationContext* opCtx) {
         return status;
     }
 
+    Grid::get(opCtx)->setShardingInitialized();
+
     return Status::OK();
 }