SERVER-39512 Make Database class thread-safe

7 files changed, 66 insertions, 76 deletions

diff --git a/src/mongo/db/catalog/database.h b/src/mongo/db/catalog/database.h
index 69b9975bb67..512e6e040ea 100644
--- a/src/mongo/db/catalog/database.h
+++ b/src/mongo/db/catalog/database.h
@@ -65,7 +65,7 @@ public:
                                 const NamespaceString& fullns,
                                 CollectionOptions collectionOptions,
                                 bool createDefaultIndexes = true,
-                                const BSONObj& idIndex = BSONObj()) = 0;
+                                const BSONObj& idIndex = BSONObj()) const = 0;
 
     Database() = default;
 
@@ -81,14 +81,14 @@ public:
     /**
      * Sets up internal memory structures.
      */
-    virtual void init(OperationContext* opCtx) = 0;
+    virtual void init(OperationContext* opCtx) const = 0;
 
     // closes files and other cleanup see below.
-    virtual void close(OperationContext* const opCtx) = 0;
+    virtual void close(OperationContext* const opCtx) const = 0;
 
     virtual const std::string& name() const = 0;
 
-    virtual void clearTmpCollections(OperationContext* const opCtx) = 0;
+    virtual void clearTmpCollections(OperationContext* const opCtx) const = 0;
 
     /**
      * Sets a new profiling level for the database and returns the outcome.
@@ -118,7 +118,7 @@ public:
 
     virtual void getStats(OperationContext* const opCtx,
                           BSONObjBuilder* const output,
-                          const double scale = 1) = 0;
+                          const double scale = 1) const = 0;
 
     virtual const DatabaseCatalogEntry* getDatabaseCatalogEntry() const = 0;
 
@@ -134,22 +134,23 @@ public:
      */
     virtual Status dropCollection(OperationContext* const opCtx,
                                   const StringData fullns,
-                                  repl::OpTime dropOpTime = {}) = 0;
+                                  repl::OpTime dropOpTime = {}) const = 0;
     virtual Status dropCollectionEvenIfSystem(OperationContext* const opCtx,
                                               const NamespaceString& fullns,
-                                              repl::OpTime dropOpTime = {}) = 0;
+                                              repl::OpTime dropOpTime = {}) const = 0;
 
-    virtual Status dropView(OperationContext* const opCtx, const NamespaceString& viewName) = 0;
+    virtual Status dropView(OperationContext* const opCtx,
+                            const NamespaceString& viewName) const = 0;
 
     virtual Collection* createCollection(OperationContext* const opCtx,
                                          StringData ns,
                                          const CollectionOptions& options = CollectionOptions(),
                                          const bool createDefaultIndexes = true,
-                                         const BSONObj& idIndex = BSONObj()) = 0;
+                                         const BSONObj& idIndex = BSONObj()) const = 0;
 
     virtual Status createView(OperationContext* const opCtx,
                               const NamespaceString& viewName,
-                              const CollectionOptions& options) = 0;
+                              const CollectionOptions& options) const = 0;
 
     /**
      * @param ns - this is fully qualified, which is maybe not ideal ???
@@ -159,12 +160,12 @@ public:
     virtual Collection* getCollection(OperationContext* opCtx, const NamespaceString& ns) const = 0;
 
     virtual Collection* getOrCreateCollection(OperationContext* const opCtx,
-                                              const NamespaceString& nss) = 0;
+                                              const NamespaceString& nss) const = 0;
 
     virtual Status renameCollection(OperationContext* const opCtx,
                                     const StringData fromNS,
                                     const StringData toNS,
-                                    const bool stayTemp) = 0;
+                                    const bool stayTemp) const = 0;
 
     virtual const std::string& getSystemViewsName() const = 0;
 
@@ -186,7 +187,7 @@ public:
      * database, we also gather a list of drop-pending collection namespaces for the
      * DropPendingCollectionReaper to clean up eventually.
      */
-    virtual void checkForIdIndexesAndDropPendingCollections(OperationContext* opCtx) = 0;
+    virtual void checkForIdIndexesAndDropPendingCollections(OperationContext* opCtx) const = 0;
 
     /**
      * A database is assigned a new epoch whenever it is closed and re-opened. This involves
diff --git a/src/mongo/db/catalog/database_impl.cpp b/src/mongo/db/catalog/database_impl.cpp
index b15efab21aa..49dadda173c 100644
--- a/src/mongo/db/catalog/database_impl.cpp
+++ b/src/mongo/db/catalog/database_impl.cpp
@@ -124,7 +124,7 @@ void uassertNamespaceNotIndex(StringData ns, StringData caller) {
             NamespaceString::normal(ns));
 }
 
-void DatabaseImpl::close(OperationContext* opCtx) {
+void DatabaseImpl::close(OperationContext* opCtx) const {
     invariant(opCtx->lockState()->isW());
 
     // Clear cache of oplog Collection pointer.
@@ -161,9 +161,10 @@ DatabaseImpl::DatabaseImpl(const StringData name, DatabaseCatalogEntry* dbEntry,
     auto viewCatalog = std::make_unique<ViewCatalog>(std::move(durableViewCatalog));
 
     ViewCatalog::set(this, std::move(viewCatalog));
+    _profile.store(serverGlobalParams.defaultProfile);
 }
 
-void DatabaseImpl::init(OperationContext* const opCtx) {
+void DatabaseImpl::init(OperationContext* const opCtx) const {
     Status status = validateDBName(_name);
 
     if (!status.isOK()) {
@@ -171,8 +172,6 @@ void DatabaseImpl::init(OperationContext* const opCtx) {
         uasserted(10028, status.toString());
     }
 
-    _profile = serverGlobalParams.defaultProfile;
-
     std::list<std::string> collections;
     _dbEntry->getCollectionNamespaces(&collections);
 
@@ -205,7 +204,7 @@ void DatabaseImpl::init(OperationContext* const opCtx) {
     }
 }
 
-void DatabaseImpl::clearTmpCollections(OperationContext* opCtx) {
+void DatabaseImpl::clearTmpCollections(OperationContext* opCtx) const {
     invariant(opCtx->lockState()->isDbLockedForMode(name(), MODE_X));
 
     std::list<std::string> collections;
@@ -239,12 +238,14 @@ void DatabaseImpl::clearTmpCollections(OperationContext* opCtx) {
 }
 
 Status DatabaseImpl::setProfilingLevel(OperationContext* opCtx, int newLevel) {
-    if (_profile == newLevel) {
+    auto currLevel = _profile.load();
+
+    if (currLevel == newLevel) {
         return Status::OK();
     }
 
     if (newLevel == 0) {
-        _profile = 0;
+        _profile.store(0);
         return Status::OK();
     }
 
@@ -264,27 +265,23 @@ Status DatabaseImpl::setProfilingLevel(OperationContext* opCtx, int newLevel) {
         return status;
     }
 
-    _profile = newLevel;
+    _profile.store(newLevel);
 
     return Status::OK();
 }
 
 void DatabaseImpl::setDropPending(OperationContext* opCtx, bool dropPending) {
-    if (dropPending) {
-        invariant(opCtx->lockState()->isDbLockedForMode(name(), MODE_X));
-        _dropPending = true;
-    } else {
-        invariant(opCtx->lockState()->isDbLockedForMode(name(), MODE_IX));
-        _dropPending = false;
-    }
+    auto mode = dropPending ? MODE_X : MODE_IX;
+    invariant(opCtx->lockState()->isDbLockedForMode(name(), mode));
+    _dropPending.store(dropPending);
 }
 
 bool DatabaseImpl::isDropPending(OperationContext* opCtx) const {
     invariant(opCtx->lockState()->isDbLockedForMode(name(), MODE_X));
-    return _dropPending;
+    return _dropPending.load();
 }
 
-void DatabaseImpl::getStats(OperationContext* opCtx, BSONObjBuilder* output, double scale) {
+void DatabaseImpl::getStats(OperationContext* opCtx, BSONObjBuilder* output, double scale) const {
 
     long long nCollections = 0;
     long long nViews = 0;
@@ -350,7 +347,7 @@ void DatabaseImpl::getStats(OperationContext* opCtx, BSONObjBuilder* output, dou
     }
 }
 
-Status DatabaseImpl::dropView(OperationContext* opCtx, const NamespaceString& viewName) {
+Status DatabaseImpl::dropView(OperationContext* opCtx, const NamespaceString& viewName) const {
     dassert(opCtx->lockState()->isDbLockedForMode(name(), MODE_IX));
     dassert(opCtx->lockState()->isCollectionLockedForMode(viewName, MODE_IX));
     dassert(opCtx->lockState()->isCollectionLockedForMode(NamespaceString(_viewsName), MODE_X));
@@ -363,7 +360,7 @@ Status DatabaseImpl::dropView(OperationContext* opCtx, const NamespaceString& vi
 
 Status DatabaseImpl::dropCollection(OperationContext* opCtx,
                                     StringData fullns,
-                                    repl::OpTime dropOpTime) {
+                                    repl::OpTime dropOpTime) const {
     if (!getCollection(opCtx, fullns)) {
         // Collection doesn't exist so don't bother validating if it can be dropped.
         return Status::OK();
@@ -375,7 +372,7 @@ Status DatabaseImpl::dropCollection(OperationContext* opCtx,
 
         if (nss.isSystem()) {
             if (nss.isSystemDotProfile()) {
-                if (_profile != 0)
+                if (_profile.load() != 0)
                     return Status(ErrorCodes::IllegalOperation,
                                   "turn off profiling before dropping system.profile collection");
             } else if (!(nss.isSystemDotViews() || nss.isHealthlog() ||
@@ -392,7 +389,7 @@ Status DatabaseImpl::dropCollection(OperationContext* opCtx,
 
 Status DatabaseImpl::dropCollectionEvenIfSystem(OperationContext* opCtx,
                                                 const NamespaceString& fullns,
-                                                repl::OpTime dropOpTime) {
+                                                repl::OpTime dropOpTime) const {
     invariant(opCtx->lockState()->isDbLockedForMode(name(), MODE_X));
 
     LOG(1) << "dropCollection: " << fullns;
@@ -506,7 +503,7 @@ Status DatabaseImpl::dropCollectionEvenIfSystem(OperationContext* opCtx,
 
 void DatabaseImpl::_dropCollectionIndexes(OperationContext* opCtx,
                                           const NamespaceString& fullns,
-                                          Collection* collection) {
+                                          Collection* collection) const {
     invariant(_name == fullns.db());
     LOG(1) << "dropCollection: " << fullns << " - dropAllIndexes start";
     collection->getIndexCatalog()->dropAllIndexes(opCtx, true);
@@ -517,7 +514,7 @@ void DatabaseImpl::_dropCollectionIndexes(OperationContext* opCtx,
 
 Status DatabaseImpl::_finishDropCollection(OperationContext* opCtx,
                                            const NamespaceString& fullns,
-                                           Collection* collection) {
+                                           Collection* collection) const {
     auto uuid = collection->uuid();
     auto uuidString = uuid ? uuid.get().toString() : "no UUID";
     log() << "Finishing collection drop for " << fullns << " (" << uuidString << ").";
@@ -548,7 +545,7 @@ Collection* DatabaseImpl::getCollection(OperationContext* opCtx, const Namespace
 Status DatabaseImpl::renameCollection(OperationContext* opCtx,
                                       StringData fromNS,
                                       StringData toNS,
-                                      bool stayTemp) {
+                                      bool stayTemp) const {
     audit::logRenameCollection(&cc(), fromNS, toNS);
     invariant(opCtx->lockState()->isDbLockedForMode(name(), MODE_X));
 
@@ -605,7 +602,7 @@ Status DatabaseImpl::renameCollection(OperationContext* opCtx,
 }
 
 Collection* DatabaseImpl::getOrCreateCollection(OperationContext* opCtx,
-                                                const NamespaceString& nss) {
+                                                const NamespaceString& nss) const {
     Collection* c = getCollection(opCtx, nss);
 
     if (!c) {
@@ -616,7 +613,7 @@ Collection* DatabaseImpl::getOrCreateCollection(OperationContext* opCtx,
 
 void DatabaseImpl::_checkCanCreateCollection(OperationContext* opCtx,
                                              const NamespaceString& nss,
-                                             const CollectionOptions& options) {
+                                             const CollectionOptions& options) const {
     massert(17399,
             str::stream() << "Cannot create collection " << nss << " - collection already exists.",
             getCollection(opCtx, nss) == nullptr);
@@ -639,12 +636,12 @@ void DatabaseImpl::_checkCanCreateCollection(OperationContext* opCtx,
     uassert(ErrorCodes::DatabaseDropPending,
             str::stream() << "Cannot create collection " << nss
                           << " - database is in the process of being dropped.",
-            !_dropPending);
+            !_dropPending.load());
 }
 
 Status DatabaseImpl::createView(OperationContext* opCtx,
                                 const NamespaceString& viewName,
-                                const CollectionOptions& options) {
+                                const CollectionOptions& options) const {
     dassert(opCtx->lockState()->isDbLockedForMode(name(), MODE_IX));
     dassert(opCtx->lockState()->isCollectionLockedForMode(viewName, MODE_IX));
     dassert(opCtx->lockState()->isCollectionLockedForMode(NamespaceString(_viewsName), MODE_X));
@@ -667,7 +664,7 @@ Collection* DatabaseImpl::createCollection(OperationContext* opCtx,
                                            StringData ns,
                                            const CollectionOptions& options,
                                            bool createIdIndex,
-                                           const BSONObj& idIndex) {
+                                           const BSONObj& idIndex) const {
     invariant(!options.isView());
     NamespaceString nss(ns);
 
@@ -847,7 +844,7 @@ StatusWith<NamespaceString> DatabaseImpl::makeUniqueCollectionNamespace(
                       << " attempts due to namespace conflicts with existing collections.");
 }
 
-void DatabaseImpl::checkForIdIndexesAndDropPendingCollections(OperationContext* opCtx) {
+void DatabaseImpl::checkForIdIndexesAndDropPendingCollections(OperationContext* opCtx) const {
     if (name() == "local") {
         // Collections in the local database are not replicated, so we do not need an _id index on
         // any collection. For the same reason, it is not possible for the local database to contain
@@ -889,7 +886,7 @@ Status DatabaseImpl::userCreateNS(OperationContext* opCtx,
                                   const NamespaceString& fullns,
                                   CollectionOptions collectionOptions,
                                   bool createDefaultIndexes,
-                                  const BSONObj& idIndex) {
+                                  const BSONObj& idIndex) const {
     LOG(1) << "create collection " << fullns << ' ' << collectionOptions.toBSON();
 
     if (!NamespaceString::validCollectionComponent(fullns.ns()))
diff --git a/src/mongo/db/catalog/database_impl.h b/src/mongo/db/catalog/database_impl.h
index dfd66ebbb1c..68987713798 100644
--- a/src/mongo/db/catalog/database_impl.h
+++ b/src/mongo/db/catalog/database_impl.h
@@ -39,17 +39,17 @@ class DatabaseImpl final : public Database {
 public:
     explicit DatabaseImpl(StringData name, DatabaseCatalogEntry* dbEntry, uint64_t epoch);
 
-    void init(OperationContext*) final;
+    void init(OperationContext*) const final;
 
 
     // closes files and other cleanup see below.
-    void close(OperationContext* opCtx) final;
+    void close(OperationContext* opCtx) const final;
 
     const std::string& name() const final {
         return _name;
     }
 
-    void clearTmpCollections(OperationContext* opCtx) final;
+    void clearTmpCollections(OperationContext* opCtx) const final;
 
     /**
      * Sets a new profiling level for the database and returns the outcome.
@@ -60,7 +60,7 @@ public:
     Status setProfilingLevel(OperationContext* opCtx, int newLevel) final;
 
     int getProfilingLevel() const final {
-        return _profile;
+        return _profile.load();
     }
     const char* getProfilingNS() const final {
         return _profileName.c_str();
@@ -70,7 +70,7 @@ public:
 
     bool isDropPending(OperationContext* opCtx) const final;
 
-    void getStats(OperationContext* opCtx, BSONObjBuilder* output, double scale = 1) final;
+    void getStats(OperationContext* opCtx, BSONObjBuilder* output, double scale = 1) const final;
 
     const DatabaseCatalogEntry* getDatabaseCatalogEntry() const final;
 
@@ -86,28 +86,28 @@ public:
      */
     Status dropCollection(OperationContext* opCtx,
                           StringData fullns,
-                          repl::OpTime dropOpTime) final;
+                          repl::OpTime dropOpTime) const final;
     Status dropCollectionEvenIfSystem(OperationContext* opCtx,
                                       const NamespaceString& fullns,
-                                      repl::OpTime dropOpTime) final;
+                                      repl::OpTime dropOpTime) const final;
 
-    Status dropView(OperationContext* opCtx, const NamespaceString& viewName) final;
+    Status dropView(OperationContext* opCtx, const NamespaceString& viewName) const final;
 
     Status userCreateNS(OperationContext* opCtx,
                         const NamespaceString& fullns,
                         CollectionOptions collectionOptions,
                         bool createDefaultIndexes,
-                        const BSONObj& idIndex) final;
+                        const BSONObj& idIndex) const final;
 
     Collection* createCollection(OperationContext* opCtx,
                                  StringData ns,
                                  const CollectionOptions& options = CollectionOptions(),
                                  bool createDefaultIndexes = true,
-                                 const BSONObj& idIndex = BSONObj()) final;
+                                 const BSONObj& idIndex = BSONObj()) const final;
 
     Status createView(OperationContext* opCtx,
                       const NamespaceString& viewName,
-                      const CollectionOptions& options) final;
+                      const CollectionOptions& options) const final;
 
     /**
      * @param ns - this is fully qualified, which is maybe not ideal ???
@@ -116,7 +116,8 @@ public:
 
     Collection* getCollection(OperationContext* opCtx, const NamespaceString& ns) const;
 
-    Collection* getOrCreateCollection(OperationContext* opCtx, const NamespaceString& nss) final;
+    Collection* getOrCreateCollection(OperationContext* opCtx,
+                                      const NamespaceString& nss) const final;
 
     /**
      * Renames the fully qualified namespace 'fromNS' to the fully qualified namespace 'toNS'.
@@ -129,16 +130,7 @@ public:
     Status renameCollection(OperationContext* opCtx,
                             StringData fromNS,
                             StringData toNS,
-                            bool stayTemp) final;
-
-    /**
-     * Physically drops the specified opened database and removes it from the server's metadata. It
-     * doesn't notify the replication subsystem or do any other consistency checks, so it should
-     * not be used directly from user commands.
-     *
-     * Must be called with the specified database locked in X mode.
-     */
-    static void dropDatabase(OperationContext* opCtx, Database* db);
+                            bool stayTemp) const final;
 
     static Status validateDBName(StringData dbname);
 
@@ -149,7 +141,7 @@ public:
     StatusWith<NamespaceString> makeUniqueCollectionNamespace(OperationContext* opCtx,
                                                               StringData collectionNameModel) final;
 
-    void checkForIdIndexesAndDropPendingCollections(OperationContext* opCtx) final;
+    void checkForIdIndexesAndDropPendingCollections(OperationContext* opCtx) const final;
 
     UUIDCatalog::iterator begin(OperationContext* opCtx) const final {
         return UUIDCatalog::get(opCtx).begin(_name);
@@ -169,7 +161,7 @@ private:
      */
     void _checkCanCreateCollection(OperationContext* opCtx,
                                    const NamespaceString& nss,
-                                   const CollectionOptions& options);
+                                   const CollectionOptions& options) const;
 
     /**
      * Completes a collection drop by removing the collection itself from the storage engine.
@@ -179,14 +171,14 @@ private:
      */
     Status _finishDropCollection(OperationContext* opCtx,
                                  const NamespaceString& fullns,
-                                 Collection* collection);
+                                 Collection* collection) const;
 
     /**
      * Removes all indexes for a collection.
      */
     void _dropCollectionIndexes(OperationContext* opCtx,
                                 const NamespaceString& fullns,
-                                Collection* collection);
+                                Collection* collection) const;
 
     const std::string _name;  // "dbname"
 
@@ -197,12 +189,12 @@ private:
     const std::string _profileName;  // "dbname.system.profile"
     const std::string _viewsName;    // "dbname.system.views"
 
-    int _profile;  // 0=off.
+    AtomicWord<int> _profile{0};  // 0=off
 
     // If '_dropPending' is true, this Database is in the midst of a two-phase drop. No new
     // collections may be created in this Database.
     // This variable may only be read/written while the database is locked in MODE_X.
-    bool _dropPending = false;
+    AtomicWord<bool> _dropPending{false};
 
     // Random number generator used to create unique collection namespaces suitable for temporary
     // collections. Lazily created on first call to makeUniqueCollectionNamespace().
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index 0aa23a1a07c..0c86e4449bd 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -2093,7 +2093,7 @@ void initTimestampFromOplog(OperationContext* opCtx, const std::string& oplogNS)
     }
 }
 
-void oplogCheckCloseDatabase(OperationContext* opCtx, Database* db) {
+void oplogCheckCloseDatabase(OperationContext* opCtx, const Database* db) {
     invariant(opCtx->lockState()->isW());
     if (db->name() == "local") {
         localOplogInfo(opCtx->getServiceContext()).oplog = nullptr;
diff --git a/src/mongo/db/repl/oplog.h b/src/mongo/db/repl/oplog.h
index 86be44cc30d..5879fc0297d 100644
--- a/src/mongo/db/repl/oplog.h
+++ b/src/mongo/db/repl/oplog.h
@@ -151,7 +151,7 @@ OpTime logOp(OperationContext* opCtx,
 
 // Flush out the cached pointer to the oplog.
 // Used by the closeDatabase command to ensure we don't cache closed things.
-void oplogCheckCloseDatabase(OperationContext* opCtx, Database* db);
+void oplogCheckCloseDatabase(OperationContext* opCtx, const Database* db);
 
 /**
  * Establish the cached pointer to the local oplog.
diff --git a/src/mongo/db/views/view_catalog.cpp b/src/mongo/db/views/view_catalog.cpp
index c932c365983..f77f6991b59 100644
--- a/src/mongo/db/views/view_catalog.cpp
+++ b/src/mongo/db/views/view_catalog.cpp
@@ -73,7 +73,7 @@ StatusWith<std::unique_ptr<CollatorInterface>> parseCollator(OperationContext* o
 }
 }  // namespace
 
-ViewCatalog* ViewCatalog::get(Database* db) {
+ViewCatalog* ViewCatalog::get(const Database* db) {
     return getViewCatalog(db).get();
 }
 
diff --git a/src/mongo/db/views/view_catalog.h b/src/mongo/db/views/view_catalog.h
index 08ed7c72422..7e92ea3afad 100644
--- a/src/mongo/db/views/view_catalog.h
+++ b/src/mongo/db/views/view_catalog.h
@@ -67,7 +67,7 @@ public:
     using ViewMap = StringMap<std::shared_ptr<ViewDefinition>>;
     using ViewIteratorCallback = stdx::function<void(const ViewDefinition& view)>;
 
-    static ViewCatalog* get(Database* db);
+    static ViewCatalog* get(const Database* db);
     static void set(Database* db, std::unique_ptr<ViewCatalog> catalog);
 
     explicit ViewCatalog(std::unique_ptr<DurableViewCatalog> durable)