SERVER-32645 Create a shim helper framework.

The `MONGO_DECLARE_SHIM`, `MONGO_DEFINE_SHIM`, and `MONGO_REGISTER_SHIM`
macros can be used to create specialized types which are customization
and auto-registration points for late-binding functions.  In some
sense they work like weak-symbols; however, they also are useful for
tracking dependencies upon shimmed-out implementations.

7 files changed, 15 insertions, 13 deletions

diff --git a/src/mongo/db/commands/create_indexes.cpp b/src/mongo/db/commands/create_indexes.cpp
index eb3b197278f..bf1edf90884 100644
--- a/src/mongo/db/commands/create_indexes.cpp
+++ b/src/mongo/db/commands/create_indexes.cpp
@@ -269,9 +269,9 @@ public:
                        str::stream() << "Not primary while creating indexes in " << ns.ns()));
         }
 
-        Database* db = dbHolder().get(opCtx, ns.db());
+        Database* db = DatabaseHolder::getDatabaseHolder().get(opCtx, ns.db());
         if (!db) {
-            db = dbHolder().openDb(opCtx, ns.db());
+            db = DatabaseHolder::getDatabaseHolder().openDb(opCtx, ns.db());
         }
         DatabaseShardingState::get(db).checkDbVersion(opCtx);
 
@@ -393,7 +393,7 @@ public:
                     str::stream() << "Not primary while completing index build in " << dbname,
                     repl::ReplicationCoordinator::get(opCtx)->canAcceptWritesFor(opCtx, ns));
 
-            Database* db = dbHolder().get(opCtx, ns.db());
+            Database* db = DatabaseHolder::getDatabaseHolder().get(opCtx, ns.db());
             if (db) {
                 DatabaseShardingState::get(db).checkDbVersion(opCtx);
             }
diff --git a/src/mongo/db/commands/dbcommands.cpp b/src/mongo/db/commands/dbcommands.cpp
index 34e2ed22f5b..ed753c7392a 100644
--- a/src/mongo/db/commands/dbcommands.cpp
+++ b/src/mongo/db/commands/dbcommands.cpp
@@ -210,7 +210,7 @@ public:
 
         // Closing a database requires a global lock.
         Lock::GlobalWrite lk(opCtx);
-        auto db = dbHolder().get(opCtx, dbname);
+        auto db = DatabaseHolder::getDatabaseHolder().get(opCtx, dbname);
         if (db) {
             if (db->isDropPending(opCtx)) {
                 return CommandHelpers::appendCommandStatus(
@@ -221,7 +221,8 @@ public:
             }
         } else {
             // If the name doesn't make an exact match, check for a case insensitive match.
-            std::set<std::string> otherCasing = dbHolder().getNamesWithConflictingCasing(dbname);
+            std::set<std::string> otherCasing =
+                DatabaseHolder::getDatabaseHolder().getNamesWithConflictingCasing(dbname);
             if (otherCasing.empty()) {
                 // Database doesn't exist. Treat this as a success (historical behavior).
                 return true;
@@ -255,7 +256,7 @@ public:
             opCtx, engine, dbname, preserveClonedFilesOnFailure, backupOriginalFiles);
 
         // Open database before returning
-        dbHolder().openDb(opCtx, dbname);
+        DatabaseHolder::getDatabaseHolder().openDb(opCtx, dbname);
         return CommandHelpers::appendCommandStatus(result, status);
     }
 } cmdRepairDatabase;
diff --git a/src/mongo/db/commands/dbcommands_d.cpp b/src/mongo/db/commands/dbcommands_d.cpp
index a0b4be7ebd1..90ab6c70bfa 100644
--- a/src/mongo/db/commands/dbcommands_d.cpp
+++ b/src/mongo/db/commands/dbcommands_d.cpp
@@ -128,7 +128,7 @@ protected:
             if (!db) {
                 // When setting the profiling level, create the database if it didn't already exist.
                 // When just reading the profiling level, we do not create the database.
-                db = dbHolder().openDb(opCtx, dbName);
+                db = DatabaseHolder::getDatabaseHolder().openDb(opCtx, dbName);
             }
             uassertStatusOK(db->setProfilingLevel(opCtx, profilingLevel));
         }
diff --git a/src/mongo/db/commands/find_and_modify.cpp b/src/mongo/db/commands/find_and_modify.cpp
index 5190d97bf1f..3a36c306626 100644
--- a/src/mongo/db/commands/find_and_modify.cpp
+++ b/src/mongo/db/commands/find_and_modify.cpp
@@ -480,8 +480,8 @@ public:
                     if (!collection) {
                         uassertStatusOK(userAllowedCreateNS(nsString.db(), nsString.coll()));
                         WriteUnitOfWork wuow(opCtx);
-                        uassertStatusOK(
-                            userCreateNS(opCtx, autoDb->getDb(), nsString.ns(), BSONObj()));
+                        uassertStatusOK(Database::userCreateNS(
+                            opCtx, autoDb->getDb(), nsString.ns(), BSONObj()));
                         wuow.commit();
 
                         collection = autoDb->getDb()->getCollection(opCtx, nsString);
diff --git a/src/mongo/db/commands/mr.cpp b/src/mongo/db/commands/mr.cpp
index 476fd6b5d3e..c743a951ba5 100644
--- a/src/mongo/db/commands/mr.cpp
+++ b/src/mongo/db/commands/mr.cpp
@@ -393,7 +393,8 @@ void State::dropTempCollections() {
 
         writeConflictRetry(_opCtx, "M/R dropTempCollections", _config.incLong.ns(), [this] {
             Lock::DBLock lk(_opCtx, _config.incLong.db(), MODE_X);
-            if (Database* db = dbHolder().get(_opCtx, _config.incLong.ns())) {
+            if (Database* db =
+                    DatabaseHolder::getDatabaseHolder().get(_opCtx, _config.incLong.ns())) {
                 WriteUnitOfWork wunit(_opCtx);
                 uassertStatusOK(db->dropCollection(_opCtx, _config.incLong.ns()));
                 wunit.commit();
@@ -653,7 +654,7 @@ unsigned long long _collectionCount(OperationContext* opCtx,
     // If the global write lock is held, we must avoid using AutoGetCollectionForReadCommand as it
     // may lead to deadlock when waiting for a majority snapshot to be committed. See SERVER-24596.
     if (callerHoldsGlobalLock) {
-        Database* db = dbHolder().get(opCtx, nss.ns());
+        Database* db = DatabaseHolder::getDatabaseHolder().get(opCtx, nss.ns());
         if (db) {
             coll = db->getCollection(opCtx, nss);
         }
diff --git a/src/mongo/db/commands/resize_oplog.cpp b/src/mongo/db/commands/resize_oplog.cpp
index d82c4321695..726cf043b5d 100644
--- a/src/mongo/db/commands/resize_oplog.cpp
+++ b/src/mongo/db/commands/resize_oplog.cpp
@@ -87,7 +87,7 @@ public:
              BSONObjBuilder& result) {
         const NamespaceString nss("local", "oplog.rs");
         Lock::GlobalWrite global(opCtx);
-        Database* database = dbHolder().get(opCtx, nss.db());
+        Database* database = DatabaseHolder::getDatabaseHolder().get(opCtx, nss.db());
         if (!database) {
             return CommandHelpers::appendCommandStatus(
                 result, Status(ErrorCodes::NamespaceNotFound, "database local does not exist"));
diff --git a/src/mongo/db/commands/restart_catalog_command.cpp b/src/mongo/db/commands/restart_catalog_command.cpp
index a3aefcd3168..f840f7954bc 100644
--- a/src/mongo/db/commands/restart_catalog_command.cpp
+++ b/src/mongo/db/commands/restart_catalog_command.cpp
@@ -95,7 +95,7 @@ public:
         std::vector<std::string> allDbs;
         getGlobalServiceContext()->getGlobalStorageEngine()->listDatabases(&allDbs);
         for (auto&& dbName : allDbs) {
-            const auto db = dbHolder().get(opCtx, dbName);
+            const auto db = DatabaseHolder::getDatabaseHolder().get(opCtx, dbName);
             if (db->isDropPending(opCtx)) {
                 return CommandHelpers::appendCommandStatus(
                     result,