SERVER-44322 Fail gracefully when the storage engine has failed to initialize

This commit is only on v3.6 as an alternative to a full backport of SERVER-34798.

2 files changed, 13 insertions, 3 deletions

diff --git a/src/mongo/db/service_context.cpp b/src/mongo/db/service_context.cpp
index 25c84c48882..719f2c2dadb 100644
--- a/src/mongo/db/service_context.cpp
+++ b/src/mongo/db/service_context.cpp
@@ -28,6 +28,8 @@
  *    it in the license file.
  */
 
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kDefault
+
 #include "mongo/platform/basic.h"
 
 #include "mongo/db/service_context.h"
@@ -41,6 +43,7 @@
 #include "mongo/transport/session.h"
 #include "mongo/transport/transport_layer.h"
 #include "mongo/util/assert_util.h"
+#include "mongo/util/log.h"
 #include "mongo/util/mongoutils/str.h"
 #include "mongo/util/system_clock_source.h"
 #include "mongo/util/system_tick_source.h"
@@ -93,7 +96,11 @@ bool supportsDocLocking() {
 bool isMMAPV1() {
     StorageEngine* globalStorageEngine = getGlobalServiceContext()->getGlobalStorageEngine();
 
-    invariant(globalStorageEngine);
+    if (!globalStorageEngine) {
+        warning()
+            << "Attempted to check if storage engine is MMAPv1 without an existing storage engine.";
+        return false;
+    }
     return globalStorageEngine->isMmapV1();
 }
 
diff --git a/src/mongo/db/service_context_d.cpp b/src/mongo/db/service_context_d.cpp
index d3be43d88ed..7fbb189194d 100644
--- a/src/mongo/db/service_context_d.cpp
+++ b/src/mongo/db/service_context_d.cpp
@@ -268,13 +268,16 @@ std::unique_ptr<OperationContext> ServiceContextMongoD::_newOpCtx(Client* client
     invariant(&cc() == client);
     auto opCtx = stdx::make_unique<OperationContext>(client, opId);
 
-    if (isMMAPV1()) {
+    auto globalStorageEngine = getGlobalStorageEngine();
+    invariant(globalStorageEngine);
+
+    if (globalStorageEngine->isMmapV1()) {
         opCtx->setLockState(stdx::make_unique<MMAPV1LockerImpl>());
     } else {
         opCtx->setLockState(stdx::make_unique<DefaultLockerImpl>());
     }
 
-    opCtx->setRecoveryUnit(getGlobalStorageEngine()->newRecoveryUnit(),
+    opCtx->setRecoveryUnit(globalStorageEngine->newRecoveryUnit(),
                            OperationContext::kNotInUnitOfWork);
     return opCtx;
 }