SERVER-14395 Clean up StorageEngine initialization and shutdown

* Added StorageEngine::cleanShutdown() and commented that the destructor will
  never be called.

* MMapV1StorageEngine specific operations were pulled into its constructor
  and cleanShutdown implementation.

* StorageEngines are now constructed at a point where it is safe to spawn
  threads.

1 files changed, 20 insertions, 2 deletions

diff --git a/src/mongo/db/storage/storage_engine.h b/src/mongo/db/storage/storage_engine.h
index f75fde343e4..66fa954d8fa 100644
--- a/src/mongo/db/storage/storage_engine.h
+++ b/src/mongo/db/storage/storage_engine.h
@@ -44,7 +44,6 @@ namespace mongo {
 
     class StorageEngine {
     public:
-        virtual ~StorageEngine() {}
 
         virtual RecoveryUnit* newRecoveryUnit( OperationContext* opCtx ) = 0;
 
@@ -61,11 +60,18 @@ namespace mongo {
          */
         virtual int flushAllFiles( bool sync ) = 0;
 
-        virtual Status repairDatabase( OperationContext* tnx,
+        virtual Status repairDatabase( OperationContext* txn,
                                        const std::string& dbName,
                                        bool preserveClonedFilesOnFailure = false,
                                        bool backupOriginalFiles = false ) = 0;
 
+        /**
+         * Will be called before a clean shutdown.
+         * Override if you have clean-up to do that is different from unclean shutdown.
+         * There is intentionally no uncleanShutdown().
+         */
+        virtual void cleanShutdown(OperationContext* txn) {}
+
         class Factory {
         public:
             virtual ~Factory(){}
@@ -73,8 +79,20 @@ namespace mongo {
         };
 
         static void registerFactory( const std::string& name, const Factory* factory );
+
+    protected:
+        /**
+         * The destructor will never be called. See cleanShutdown instead.
+         */
+        virtual ~StorageEngine() {}
     };
 
+    /**
+     * Sets up the globalStorageEngine pointer and performs any startup work needed by the selected
+     * storage engine. This must be called at a point where it is safe to spawn worker threads.
+     */
+    void initGlobalStorageEngine();
+
     // TODO: this is temporary
     extern StorageEngine* globalStorageEngine;
 }