SERVER-51091 Rearrange AutoGetCollection templating and inheritance to have separate -LFR and non-LFR (lock-free read) lock helpers.

4 files changed, 99 insertions, 126 deletions

diff --git a/src/mongo/db/catalog_raii.cpp b/src/mongo/db/catalog_raii.cpp
index 41e5e2576b6..f19b9738453 100644
--- a/src/mongo/db/catalog_raii.cpp
+++ b/src/mongo/db/catalog_raii.cpp
@@ -69,14 +69,13 @@ Database* AutoGetDb::ensureDbExists() {
     return _db;
 }
 
-template <typename CatalogCollectionLookupT>
-AutoGetCollectionBase<CatalogCollectionLookupT>::AutoGetCollectionBase(
-    OperationContext* opCtx,
-    const NamespaceStringOrUUID& nsOrUUID,
-    LockMode modeColl,
-    AutoGetCollectionViewMode viewMode,
-    Date_t deadline)
-    : _autoDb(opCtx,
+AutoGetCollection::AutoGetCollection(OperationContext* opCtx,
+                                     const NamespaceStringOrUUID& nsOrUUID,
+                                     LockMode modeColl,
+                                     AutoGetCollectionViewMode viewMode,
+                                     Date_t deadline)
+    : _opCtx(opCtx),
+      _autoDb(opCtx,
               !nsOrUUID.dbname().empty() ? nsOrUUID.dbname() : nsOrUUID.nss()->db(),
               isSharedLockMode(modeColl) ? MODE_IS : MODE_IX,
               deadline) {
@@ -112,7 +111,7 @@ AutoGetCollectionBase<CatalogCollectionLookupT>::AutoGetCollectionBase(
     if (!db)
         return;
 
-    _coll = _lookup.lookupCollection(opCtx, _resolvedNss);
+    _coll = CollectionCatalog::get(opCtx).lookupCollectionByNamespace(opCtx, _resolvedNss);
     invariant(!nsOrUUID.uuid() || _coll,
               str::stream() << "Collection for " << _resolvedNss.ns()
                             << " disappeared after successufully resolving "
@@ -149,13 +148,6 @@ AutoGetCollectionBase<CatalogCollectionLookupT>::AutoGetCollectionBase(
             !_view || viewMode == AutoGetCollectionViewMode::kViewsPermitted);
 }
 
-AutoGetCollection::AutoGetCollection(OperationContext* opCtx,
-                                     const NamespaceStringOrUUID& nsOrUUID,
-                                     LockMode modeColl,
-                                     AutoGetCollectionViewMode viewMode,
-                                     Date_t deadline)
-    : AutoGetCollectionBase(opCtx, nsOrUUID, modeColl, viewMode, deadline), _opCtx(opCtx) {}
-
 Collection* AutoGetCollection::getWritableCollection(CollectionCatalog::LifetimeMode mode) {
     // Acquire writable instance if not already available
     if (!_writableColl) {
@@ -320,18 +312,6 @@ void CollectionWriter::commitToCatalog() {
     _writableCollection = nullptr;
 }
 
-CatalogCollectionLookup::CollectionStorage CatalogCollectionLookup::lookupCollection(
-    OperationContext* opCtx, const NamespaceString& nss) {
-    return CollectionCatalog::get(opCtx).lookupCollectionByNamespace(opCtx, nss);
-}
-
-CatalogCollectionLookupForRead::CollectionStorage CatalogCollectionLookupForRead::lookupCollection(
-    OperationContext* opCtx, const NamespaceString& nss) {
-    auto ptr = CollectionCatalog::get(opCtx).lookupCollectionByNamespaceForRead(opCtx, nss);
-    _collection = CollectionPtr(ptr);
-    return ptr;
-}
-
 LockMode fixLockModeForSystemDotViewsChanges(const NamespaceString& nss, LockMode mode) {
     return nss.isSystemDotViews() ? MODE_X : mode;
 }
@@ -390,7 +370,4 @@ AutoGetOplog::AutoGetOplog(OperationContext* opCtx, OplogAccessMode mode, Date_t
     _oplog = &_oplogInfo->getCollection();
 }
 
-template class AutoGetCollectionBase<CatalogCollectionLookup>;
-template class AutoGetCollectionBase<CatalogCollectionLookupForRead>;
-
 }  // namespace mongo
diff --git a/src/mongo/db/catalog_raii.h b/src/mongo/db/catalog_raii.h
index 76fe75ba9c8..eade7f99c4b 100644
--- a/src/mongo/db/catalog_raii.h
+++ b/src/mongo/db/catalog_raii.h
@@ -82,6 +82,8 @@ private:
     Database* _db;
 };
 
+enum class AutoGetCollectionViewMode { kViewsPermitted, kViewsForbidden };
+
 /**
  * RAII-style class, which acquires global, database, and collection locks according to the chart
  * below.
@@ -98,18 +100,12 @@ private:
  * Any acquired locks may be released when this object goes out of scope, therefore the database
  * and the collection references returned by this class should not be retained.
  */
-
-enum class AutoGetCollectionViewMode { kViewsPermitted, kViewsForbidden };
-
-template <typename CatalogCollectionLookupT>
-class AutoGetCollectionBase {
-    AutoGetCollectionBase(const AutoGetCollectionBase&) = delete;
-    AutoGetCollectionBase& operator=(const AutoGetCollectionBase&) = delete;
-
-    using CollectionStorage = typename CatalogCollectionLookupT::CollectionStorage;
+class AutoGetCollection {
+    AutoGetCollection(const AutoGetCollection&) = delete;
+    AutoGetCollection& operator=(const AutoGetCollection&) = delete;
 
 public:
-    AutoGetCollectionBase(
+    AutoGetCollection(
         OperationContext* opCtx,
         const NamespaceStringOrUUID& nsOrUUID,
         LockMode modeColl,
@@ -152,7 +148,7 @@ public:
      * Returns nullptr if the collection didn't exist.
      */
     const CollectionPtr& getCollection() const {
-        return _lookup.toCollectionPtr(_coll);
+        return _coll;
     }
 
     /**
@@ -169,54 +165,14 @@ public:
         return _resolvedNss;
     }
 
-protected:
-    AutoGetDb _autoDb;
-
-    // If the object was instantiated with a UUID, contains the resolved namespace, otherwise it is
-    // the same as the input namespace string
-    NamespaceString _resolvedNss;
-
-    // This field is boost::optional, because in the case of lookup by UUID, the collection lock
-    // might need to be relocked for the correct namespace
-    boost::optional<Lock::CollectionLock> _collLock;
-
-    CollectionStorage _coll = nullptr;
-    CatalogCollectionLookupT _lookup;
-    std::shared_ptr<ViewDefinition> _view;
-};
-
-struct CatalogCollectionLookup {
-    using CollectionStorage = CollectionPtr;
-
-    CollectionStorage lookupCollection(OperationContext* opCtx, const NamespaceString& nss);
-    const CollectionPtr& toCollectionPtr(const CollectionStorage& collection) const {
-        return collection;
-    }
-};
-struct CatalogCollectionLookupForRead {
-    using CollectionStorage = std::shared_ptr<const Collection>;
-
-    CollectionStorage lookupCollection(OperationContext* opCtx, const NamespaceString& nss);
-    const CollectionPtr& toCollectionPtr(const CollectionStorage&) const {
-        return _collection;
-    }
-
-private:
-    CollectionPtr _collection;
-};
-
-class AutoGetCollection : public AutoGetCollectionBase<CatalogCollectionLookup> {
-public:
-    AutoGetCollection(
-        OperationContext* opCtx,
-        const NamespaceStringOrUUID& nsOrUUID,
-        LockMode modeColl,
-        AutoGetCollectionViewMode viewMode = AutoGetCollectionViewMode::kViewsForbidden,
-        Date_t deadline = Date_t::max());
-
     /**
-     * Returns writable Collection. Necessary Collection lock mode is required.
-     * Any previous Collection that has been returned may be invalidated.
+     * Returns a writable Collection copy that will be returned by current and future calls to this
+     * function as well as getCollection(). Any previous Collection pointers that were returned may
+     * be invalidated.
+     *
+     * CollectionCatalog::LifetimeMode::kManagedInWriteUnitOfWork will register an onCommit()
+     * handler to reset the pointers and an onRollback() handler that will reset getCollection() to
+     * the original Collection pointer.
      */
     Collection* getWritableCollection(
         CollectionCatalog::LifetimeMode mode =
@@ -226,9 +182,19 @@ public:
         return _opCtx;
     }
 
-private:
-    Collection* _writableColl = nullptr;
+protected:
     OperationContext* _opCtx = nullptr;
+    AutoGetDb _autoDb;
+    boost::optional<Lock::CollectionLock> _collLock;
+    CollectionPtr _coll = nullptr;
+    std::shared_ptr<ViewDefinition> _view;
+
+    // If the object was instantiated with a UUID, contains the resolved namespace, otherwise it is
+    // the same as the input namespace string
+    NamespaceString _resolvedNss;
+
+    // Populated if getWritableCollection() is called.
+    Collection* _writableColl = nullptr;
 };
 
 /**
diff --git a/src/mongo/db/db_raii.cpp b/src/mongo/db/db_raii.cpp
index 7e2397f2521..7ffe40349ab 100644
--- a/src/mongo/db/db_raii.cpp
+++ b/src/mongo/db/db_raii.cpp
@@ -84,10 +84,12 @@ AutoStatsTracker::~AutoStatsTracker() {
                 curOp->getReadWriteType());
 }
 
-AutoGetCollectionForRead::AutoGetCollectionForRead(OperationContext* opCtx,
-                                                   const NamespaceStringOrUUID& nsOrUUID,
-                                                   AutoGetCollectionViewMode viewMode,
-                                                   Date_t deadline) {
+template <typename AutoGetCollectionType>
+AutoGetCollectionForReadBase<AutoGetCollectionType>::AutoGetCollectionForReadBase(
+    OperationContext* opCtx,
+    const NamespaceStringOrUUID& nsOrUUID,
+    AutoGetCollectionViewMode viewMode,
+    Date_t deadline) {
     // The caller was expecting to conflict with batch application before entering this function.
     // i.e. the caller does not currently have a ShouldNotConflict... block in scope.
     bool callerWasConflicting = opCtx->lockState()->shouldConflictWithSecondaryBatchApplication();
@@ -241,13 +243,13 @@ AutoGetCollectionForRead::AutoGetCollectionForRead(OperationContext* opCtx,
     }
 }
 
-
-AutoGetCollectionForReadCommand::AutoGetCollectionForReadCommand(
-    OperationContext* opCtx,
-    const NamespaceStringOrUUID& nsOrUUID,
-    AutoGetCollectionViewMode viewMode,
-    Date_t deadline,
-    AutoStatsTracker::LogMode logMode)
+template <typename AutoGetCollectionForReadType>
+AutoGetCollectionForReadCommandBase<AutoGetCollectionForReadType>::
+    AutoGetCollectionForReadCommandBase(OperationContext* opCtx,
+                                        const NamespaceStringOrUUID& nsOrUUID,
+                                        AutoGetCollectionViewMode viewMode,
+                                        Date_t deadline,
+                                        AutoStatsTracker::LogMode logMode)
     : _autoCollForRead(opCtx, nsOrUUID, viewMode, deadline),
       _statsTracker(
           opCtx,
@@ -338,4 +340,7 @@ BlockSecondaryReadsDuringBatchApplication_DONT_USE::
     allowSecondaryReads->swap(_originalSettings);
 }
 
+template class AutoGetCollectionForReadBase<AutoGetCollection>;
+template class AutoGetCollectionForReadCommandBase<AutoGetCollectionForRead>;
+
 }  // namespace mongo
diff --git a/src/mongo/db/db_raii.h b/src/mongo/db/db_raii.h
index 89406e31939..dbe6b1c1b70 100644
--- a/src/mongo/db/db_raii.h
+++ b/src/mongo/db/db_raii.h
@@ -84,24 +84,13 @@ private:
     const LogMode _logMode;
 };
 
-/**
- * Same as calling AutoGetCollection with MODE_IS, but in addition ensures that the read will be
- * performed against an appropriately committed snapshot if the operation is using a readConcern of
- * 'majority'.
- *
- * Use this when you want to read the contents of a collection, but you are not at the top-level of
- * some command. This will ensure your reads obey any requested readConcern, but will not update the
- * status of CurrentOp, or add a Top entry.
- *
- * NOTE: Must not be used with any locks held, because it needs to block waiting on the committed
- * snapshot to become available.
- */
-class AutoGetCollectionForRead {
-    AutoGetCollectionForRead(const AutoGetCollectionForRead&) = delete;
-    AutoGetCollectionForRead& operator=(const AutoGetCollectionForRead&) = delete;
+template <typename AutoGetCollectionType>
+class AutoGetCollectionForReadBase {
+    AutoGetCollectionForReadBase(const AutoGetCollectionForReadBase&) = delete;
+    AutoGetCollectionForReadBase& operator=(const AutoGetCollectionForReadBase&) = delete;
 
 public:
-    AutoGetCollectionForRead(
+    AutoGetCollectionForReadBase(
         OperationContext* opCtx,
         const NamespaceStringOrUUID& nsOrUUID,
         AutoGetCollectionViewMode viewMode = AutoGetCollectionViewMode::kViewsForbidden,
@@ -140,19 +129,39 @@ private:
 
     // This field is optional, because the code to wait for majority committed snapshot needs to
     // release locks in order to block waiting
-    boost::optional<AutoGetCollectionBase<CatalogCollectionLookupForRead>> _autoColl;
+    boost::optional<AutoGetCollectionType> _autoColl;
 };
 
 /**
- * Same as AutoGetCollectionForRead, but in addition will add a Top entry upon destruction and
- * ensure the CurrentOp object has the right namespace and has started its timer.
+ * Same as calling AutoGetCollection with MODE_IS, but in addition ensures that the read will be
+ * performed against an appropriately committed snapshot if the operation is using a readConcern of
+ * 'majority'.
+ *
+ * Use this when you want to read the contents of a collection, but you are not at the top-level of
+ * some command. This will ensure your reads obey any requested readConcern, but will not update the
+ * status of CurrentOp, or add a Top entry.
+ *
+ * NOTE: Must not be used with any locks held, because it needs to block waiting on the committed
+ * snapshot to become available.
  */
-class AutoGetCollectionForReadCommand {
-    AutoGetCollectionForReadCommand(const AutoGetCollectionForReadCommand&) = delete;
-    AutoGetCollectionForReadCommand& operator=(const AutoGetCollectionForReadCommand&) = delete;
+class AutoGetCollectionForRead : public AutoGetCollectionForReadBase<AutoGetCollection> {
+public:
+    AutoGetCollectionForRead(
+        OperationContext* opCtx,
+        const NamespaceStringOrUUID& nsOrUUID,
+        AutoGetCollectionViewMode viewMode = AutoGetCollectionViewMode::kViewsForbidden,
+        Date_t deadline = Date_t::max())
+        : AutoGetCollectionForReadBase(opCtx, nsOrUUID, viewMode, deadline) {}
+};
+
+template <typename AutoGetCollectionForReadType>
+class AutoGetCollectionForReadCommandBase {
+    AutoGetCollectionForReadCommandBase(const AutoGetCollectionForReadCommandBase&) = delete;
+    AutoGetCollectionForReadCommandBase& operator=(const AutoGetCollectionForReadCommandBase&) =
+        delete;
 
 public:
-    AutoGetCollectionForReadCommand(
+    AutoGetCollectionForReadCommandBase(
         OperationContext* opCtx,
         const NamespaceStringOrUUID& nsOrUUID,
         AutoGetCollectionViewMode viewMode = AutoGetCollectionViewMode::kViewsForbidden,
@@ -184,11 +193,27 @@ public:
     }
 
 private:
-    AutoGetCollectionForRead _autoCollForRead;
+    AutoGetCollectionForReadType _autoCollForRead;
     AutoStatsTracker _statsTracker;
 };
 
 /**
+ * Same as AutoGetCollectionForRead, but in addition will add a Top entry upon destruction and
+ * ensure the CurrentOp object has the right namespace and has started its timer.
+ */
+class AutoGetCollectionForReadCommand
+    : public AutoGetCollectionForReadCommandBase<AutoGetCollectionForRead> {
+public:
+    AutoGetCollectionForReadCommand(
+        OperationContext* opCtx,
+        const NamespaceStringOrUUID& nsOrUUID,
+        AutoGetCollectionViewMode viewMode = AutoGetCollectionViewMode::kViewsForbidden,
+        Date_t deadline = Date_t::max(),
+        AutoStatsTracker::LogMode logMode = AutoStatsTracker::LogMode::kUpdateTopAndCurOp)
+        : AutoGetCollectionForReadCommandBase(opCtx, nsOrUUID, viewMode, deadline, logMode) {}
+};
+
+/**
  * Opens the database that we want to use and sets the appropriate namespace on the
  * current operation.
  */