SERVER-34798 Move storage initialization behaviors out of ServiceContext subclasses to new library.

32 files changed, 566 insertions, 507 deletions

diff --git a/src/mongo/db/SConscript b/src/mongo/db/SConscript
index fdb33e83840..a77d3d7de2e 100644
--- a/src/mongo/db/SConscript
+++ b/src/mongo/db/SConscript
@@ -699,6 +699,7 @@ env.Library(
         '$BUILD_DIR/mongo/db/concurrency/lock_manager',
         '$BUILD_DIR/mongo/db/ops/write_ops_parsers',
         '$BUILD_DIR/mongo/db/s/sharding',
+        '$BUILD_DIR/mongo/db/storage/storage_engine_common',
         '$BUILD_DIR/mongo/db/storage/storage_options',
         '$BUILD_DIR/mongo/db/storage/storage_engine_lock_file',
         '$BUILD_DIR/mongo/db/storage/storage_engine_metadata',
diff --git a/src/mongo/db/catalog/SConscript b/src/mongo/db/catalog/SConscript
index 5ed9e0ad896..47c0b0f662e 100644
--- a/src/mongo/db/catalog/SConscript
+++ b/src/mongo/db/catalog/SConscript
@@ -289,6 +289,7 @@ env.Library(
     LIBDEPS_PRIVATE=[
         '$BUILD_DIR/mongo/db/logical_clock',
         '$BUILD_DIR/mongo/db/storage/mmap_v1/mmap_v1_options',
+        '$BUILD_DIR/mongo/db/storage/storage_engine_common',
     ],
 )
 
diff --git a/src/mongo/db/catalog/database_impl.cpp b/src/mongo/db/catalog/database_impl.cpp
index 7ee8c22b7ba..b2df4e237b0 100644
--- a/src/mongo/db/catalog/database_impl.cpp
+++ b/src/mongo/db/catalog/database_impl.cpp
@@ -67,6 +67,7 @@
 #include "mongo/db/stats/top.h"
 #include "mongo/db/storage/recovery_unit.h"
 #include "mongo/db/storage/storage_engine.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_options.h"
 #include "mongo/db/system_index.h"
 #include "mongo/db/views/view_catalog.h"
@@ -92,12 +93,12 @@ namespace {
 MONGO_FP_DECLARE(hangBeforeLoggingCreateCollection);
 }  // namespace
 
-using std::unique_ptr;
 using std::endl;
 using std::list;
 using std::set;
 using std::string;
 using std::stringstream;
+using std::unique_ptr;
 using std::vector;
 
 void uassertNamespaceNotIndex(StringData ns, StringData caller) {
@@ -1019,18 +1020,19 @@ MONGO_REGISTER_SHIM(Database::userCreateNS)
         }
     }
 
-    status =
-        validateStorageOptions(collectionOptions.storageEngine, [](const auto& x, const auto& y) {
-            return x->validateCollectionStorageOptions(y);
-        });
+    status = validateStorageOptions(
+        opCtx->getServiceContext(),
+        collectionOptions.storageEngine,
+        [](const auto& x, const auto& y) { return x->validateCollectionStorageOptions(y); });
 
     if (!status.isOK())
         return status;
 
     if (auto indexOptions = collectionOptions.indexOptionDefaults["storageEngine"]) {
-        status = validateStorageOptions(indexOptions.Obj(), [](const auto& x, const auto& y) {
-            return x->validateIndexStorageOptions(y);
-        });
+        status = validateStorageOptions(
+            opCtx->getServiceContext(), indexOptions.Obj(), [](const auto& x, const auto& y) {
+                return x->validateIndexStorageOptions(y);
+            });
 
         if (!status.isOK()) {
             return status;
diff --git a/src/mongo/db/catalog/index_catalog_impl.cpp b/src/mongo/db/catalog/index_catalog_impl.cpp
index 583721aba4b..ac93349e71e 100644
--- a/src/mongo/db/catalog/index_catalog_impl.cpp
+++ b/src/mongo/db/catalog/index_catalog_impl.cpp
@@ -64,6 +64,7 @@
 #include "mongo/db/repl/replication_coordinator.h"
 #include "mongo/db/server_options.h"
 #include "mongo/db/service_context.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/util/assert_util.h"
 #include "mongo/util/log.h"
 #include "mongo/util/mongoutils/str.h"
@@ -97,9 +98,9 @@ MONGO_REGISTER_SHIM(IndexCatalog::prepareInsertDeleteOptions)
     return IndexCatalogImpl::prepareInsertDeleteOptions(opCtx, desc, options);
 }
 
-using std::unique_ptr;
 using std::endl;
 using std::string;
+using std::unique_ptr;
 using std::vector;
 
 using IndexVersion = IndexDescriptor::IndexVersion;
@@ -535,7 +536,7 @@ Status _checkValidFilterExpressions(MatchExpression* expression, int level = 0)
                                         << expression->toString());
     }
 }
-}
+}  // namespace
 
 Status IndexCatalogImpl::_isSpecOk(OperationContext* opCtx, const BSONObj& spec) const {
     const NamespaceString& nss = _collection->ns();
@@ -764,8 +765,8 @@ Status IndexCatalogImpl::_isSpecOk(OperationContext* opCtx, const BSONObj& spec)
                       "Empty \"storageEngine\" options are invalid. "
                       "Please remove the field or include valid options.");
     }
-    Status storageEngineStatus =
-        validateStorageOptions(storageEngineOptions, [](const auto& x, const auto& y) {
+    Status storageEngineStatus = validateStorageOptions(
+        opCtx->getServiceContext(), storageEngineOptions, [](const auto& x, const auto& y) {
             return x->validateIndexStorageOptions(y);
         });
     if (!storageEngineStatus.isOK()) {
diff --git a/src/mongo/db/commands/SConscript b/src/mongo/db/commands/SConscript
index 03dd3919180..b95489f622c 100644
--- a/src/mongo/db/commands/SConscript
+++ b/src/mongo/db/commands/SConscript
@@ -221,6 +221,7 @@ env.Library(
         '$BUILD_DIR/mongo/db/query_exec',
         '$BUILD_DIR/mongo/db/repair_database',
         '$BUILD_DIR/mongo/db/rw_concern_d',
+        '$BUILD_DIR/mongo/db/storage/storage_engine_common',
         '$BUILD_DIR/mongo/db/views/views_mongod',
         'core',
         'current_op_common',
diff --git a/src/mongo/db/commands/dbcommands.cpp b/src/mongo/db/commands/dbcommands.cpp
index 0499c35f683..02a279e4653 100644
--- a/src/mongo/db/commands/dbcommands.cpp
+++ b/src/mongo/db/commands/dbcommands.cpp
@@ -87,6 +87,7 @@
 #include "mongo/db/repl/replication_coordinator.h"
 #include "mongo/db/server_parameters.h"
 #include "mongo/db/stats/storage_stats.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/write_concern.h"
 #include "mongo/s/stale_exception.h"
 #include "mongo/scripting/engine.h"
@@ -94,6 +95,7 @@
 #include "mongo/util/log.h"
 #include "mongo/util/md5.hpp"
 #include "mongo/util/scopeguard.h"
+#include "mongo/util/version.h"
 
 namespace mongo {
 
@@ -764,5 +766,38 @@ public:
 
 } cmdDBStats;
 
+class CmdBuildInfo : public BasicCommand {
+public:
+    CmdBuildInfo() : BasicCommand("buildInfo", "buildinfo") {}
+
+    AllowedOnSecondary secondaryAllowed(ServiceContext*) const override {
+        return AllowedOnSecondary::kAlways;
+    }
+
+    virtual bool adminOnly() const {
+        return false;
+    }
+    virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
+        return false;
+    }
+    virtual void addRequiredPrivileges(const std::string& dbname,
+                                       const BSONObj& cmdObj,
+                                       std::vector<Privilege>* out) const {}  // No auth required
+    std::string help() const override {
+        return "get version #, etc.\n"
+               "{ buildinfo:1 }";
+    }
+
+    bool run(OperationContext* opCtx,
+             const std::string& dbname,
+             const BSONObj& jsobj,
+             BSONObjBuilder& result) {
+        VersionInfoInterface::instance().appendBuildInfo(&result);
+        appendStorageEngineList(opCtx->getServiceContext(), &result);
+        return true;
+    }
+
+} cmdBuildInfo;
+
 }  // namespace
 }  // namespace mongo
diff --git a/src/mongo/db/commands/generic.cpp b/src/mongo/db/commands/generic.cpp
index e157ff5a64a..9a4bf94a78b 100644
--- a/src/mongo/db/commands/generic.cpp
+++ b/src/mongo/db/commands/generic.cpp
@@ -38,7 +38,6 @@
 #include "mongo/util/log.h"
 #include "mongo/util/processinfo.h"
 #include "mongo/util/ramlog.h"
-#include "mongo/util/version.h"
 
 #include <sstream>
 #include <string>
@@ -51,39 +50,6 @@ using std::string;
 using std::stringstream;
 using std::vector;
 
-class CmdBuildInfo : public BasicCommand {
-public:
-    CmdBuildInfo() : BasicCommand("buildInfo", "buildinfo") {}
-
-    AllowedOnSecondary secondaryAllowed(ServiceContext*) const override {
-        return AllowedOnSecondary::kAlways;
-    }
-
-    virtual bool adminOnly() const {
-        return false;
-    }
-    virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
-        return false;
-    }
-    virtual void addRequiredPrivileges(const std::string& dbname,
-                                       const BSONObj& cmdObj,
-                                       std::vector<Privilege>* out) const {}  // No auth required
-    std::string help() const override {
-        return "get version #, etc.\n"
-               "{ buildinfo:1 }";
-    }
-
-    bool run(OperationContext* opCtx,
-             const std::string& dbname,
-             const BSONObj& jsobj,
-             BSONObjBuilder& result) {
-        VersionInfoInterface::instance().appendBuildInfo(&result);
-        appendStorageEngineList(&result);
-        return true;
-    }
-
-} cmdBuildInfo;
-
 class PingCommand : public BasicCommand {
 public:
     PingCommand() : BasicCommand("ping") {}
diff --git a/src/mongo/db/db.cpp b/src/mongo/db/db.cpp
index 957b55b633b..f9496fe49cf 100644
--- a/src/mongo/db/db.cpp
+++ b/src/mongo/db/db.cpp
@@ -40,7 +40,6 @@
 #include <signal.h>
 #include <string>
 
-#include "mongo/base/checked_cast.h"
 #include "mongo/base/init.h"
 #include "mongo/base/initializer.h"
 #include "mongo/base/status.h"
@@ -129,6 +128,7 @@
 #include "mongo/db/storage/encryption_hooks.h"
 #include "mongo/db/storage/mmap_v1/mmap_v1_options.h"
 #include "mongo/db/storage/storage_engine.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_options.h"
 #include "mongo/db/system_index.h"
 #include "mongo/db/ttl.h"
@@ -209,7 +209,7 @@ void logStartup(OperationContext* opCtx) {
 
     BSONObjBuilder buildinfo(toLog.subobjStart("buildinfo"));
     VersionInfoInterface::instance().appendBuildInfo(&buildinfo);
-    appendStorageEngineList(&buildinfo);
+    appendStorageEngineList(opCtx->getServiceContext(), &buildinfo);
     buildinfo.doneFast();
 
     BSONObj o = toLog.obj();
@@ -270,7 +270,7 @@ ExitCode _initAndListen(int listenPort) {
     Client::initThread("initandlisten");
 
     initWireSpec();
-    auto serviceContext = checked_cast<ServiceContextMongoD*>(getGlobalServiceContext());
+    auto serviceContext = getGlobalServiceContext();
 
     serviceContext->setFastClockSource(FastClockSourceFactory::create(Milliseconds(10)));
     auto opObserverRegistry = stdx::make_unique<OpObserverRegistry>();
@@ -312,7 +312,7 @@ ExitCode _initAndListen(int listenPort) {
 
     logProcessDetails();
 
-    serviceContext->createLockFile();
+    createLockFile(serviceContext);
 
     serviceContext->setServiceEntryPoint(
         stdx::make_unique<ServiceEntryPointMongod>(serviceContext));
@@ -328,7 +328,7 @@ ExitCode _initAndListen(int listenPort) {
         serviceContext->setTransportLayer(std::move(tl));
     }
 
-    serviceContext->initializeGlobalStorageEngine();
+    initializeStorageEngine(serviceContext);
 
 #ifdef MONGO_CONFIG_WIREDTIGER_ENABLED
     if (EncryptionHooks::get(serviceContext)->restartRequired()) {
@@ -348,7 +348,7 @@ ExitCode _initAndListen(int listenPort) {
             }
 
             // Warn if field name matches non-active registered storage engine.
-            if (serviceContext->isRegisteredStorageEngine(e.fieldName())) {
+            if (isRegisteredStorageEngine(serviceContext, e.fieldName())) {
                 warning() << "Detected configuration for non-active storage engine "
                           << e.fieldName() << " when current storage engine is "
                           << storageGlobalParams.engine;
@@ -931,7 +931,7 @@ void shutdownTask() {
 
     // Global storage engine may not be started in all cases before we exit
     if (serviceContext->getStorageEngine()) {
-        serviceContext->shutdownGlobalStorageEngineCleanly();
+        shutdownGlobalStorageEngineCleanly(serviceContext);
     }
 
     // We drop the scope cache because leak sanitizer can't see across the
diff --git a/src/mongo/db/service_context.cpp b/src/mongo/db/service_context.cpp
index 17193d9462a..92389a0f6a1 100644
--- a/src/mongo/db/service_context.cpp
+++ b/src/mongo/db/service_context.cpp
@@ -99,43 +99,6 @@ bool isMMAPV1() {
     return globalStorageEngine->isMmapV1();
 }
 
-Status validateStorageOptions(
-    const BSONObj& storageEngineOptions,
-    stdx::function<Status(const StorageEngine::Factory* const, const BSONObj&)> validateFunc) {
-    BSONObjIterator storageIt(storageEngineOptions);
-    while (storageIt.more()) {
-        BSONElement storageElement = storageIt.next();
-        StringData storageEngineName = storageElement.fieldNameStringData();
-        if (storageElement.type() != mongo::Object) {
-            return Status(ErrorCodes::BadValue,
-                          str::stream() << "'storageEngine." << storageElement.fieldNameStringData()
-                                        << "' has to be an embedded document.");
-        }
-
-        std::unique_ptr<StorageFactoriesIterator> sfi(
-            getGlobalServiceContext()->makeStorageFactoriesIterator());
-        invariant(sfi);
-        bool found = false;
-        while (sfi->more()) {
-            const StorageEngine::Factory* const& factory = sfi->next();
-            if (storageEngineName != factory->getCanonicalName()) {
-                continue;
-            }
-            Status status = validateFunc(factory, storageElement.Obj());
-            if (!status.isOK()) {
-                return status;
-            }
-            found = true;
-        }
-        if (!found) {
-            return Status(ErrorCodes::InvalidOptions,
-                          str::stream() << storageEngineName
-                                        << " is not a registered storage engine for this server");
-        }
-    }
-    return Status::OK();
-}
-
 ServiceContext::ServiceContext()
     : _tickSource(stdx::make_unique<SystemTickSource>()),
       _fastClockSource(stdx::make_unique<SystemClockSource>()),
@@ -300,29 +263,6 @@ Client* ServiceContext::LockedClientsCursor::next() {
     return result;
 }
 
-BSONArray storageEngineList() {
-    if (!hasGlobalServiceContext())
-        return BSONArray();
-
-    std::unique_ptr<StorageFactoriesIterator> sfi(
-        getGlobalServiceContext()->makeStorageFactoriesIterator());
-
-    if (!sfi)
-        return BSONArray();
-
-    BSONArrayBuilder engineArrayBuilder;
-
-    while (sfi->more()) {
-        engineArrayBuilder.append(sfi->next()->getCanonicalName());
-    }
-
-    return engineArrayBuilder.arr();
-}
-
-void appendStorageEngineList(BSONObjBuilder* result) {
-    result->append("storageEngines", storageEngineList());
-}
-
 void ServiceContext::setKillAllOperations() {
     stdx::lock_guard<stdx::mutex> clientLock(_mutex);
 
diff --git a/src/mongo/db/service_context.h b/src/mongo/db/service_context.h
index 1caa0fd0f05..73b272470e6 100644
--- a/src/mongo/db/service_context.h
+++ b/src/mongo/db/service_context.h
@@ -82,19 +82,6 @@ protected:
     virtual ~KillOpListenerInterface() = default;
 };
 
-class StorageFactoriesIterator {
-    MONGO_DISALLOW_COPYING(StorageFactoriesIterator);
-
-public:
-    virtual ~StorageFactoriesIterator() = default;
-
-    virtual bool more() const = 0;
-    virtual const StorageEngine::Factory* next() = 0;
-
-protected:
-    StorageFactoriesIterator() = default;
-};
-
 /**
  * Class representing the context of a service, such as a MongoD database service or
  * a MongoS routing service.
@@ -239,34 +226,6 @@ public:
     //
 
     /**
-     * Register a storage engine.  Called from a MONGO_INIT that depends on initializiation of
-     * the global environment.
-     * Ownership of 'factory' is transferred to global environment upon registration.
-     */
-    virtual void registerStorageEngine(const std::string& name,
-                                       const StorageEngine::Factory* factory) = 0;
-
-    /**
-     * Returns true if "name" refers to a registered storage engine.
-     */
-    virtual bool isRegisteredStorageEngine(const std::string& name) = 0;
-
-    /**
-     * Produce an iterator over all registered storage engine factories.
-     * Caller owns the returned object and is responsible for deleting when finished.
-     *
-     * Never returns nullptr.
-     */
-    virtual StorageFactoriesIterator* makeStorageFactoriesIterator() = 0;
-
-    virtual void initializeGlobalStorageEngine() = 0;
-
-    /**
-     * Shuts down storage engine cleanly and releases any locks on mongod.lock.
-     */
-    virtual void shutdownGlobalStorageEngineCleanly() = 0;
-
-    /**
      * Sets the storage engine for this instance. May be called up to once per instance.
      */
     void setStorageEngine(std::unique_ptr<StorageEngine> engine);
@@ -574,29 +533,4 @@ bool supportsDocLocking();
  */
 bool isMMAPV1();
 
-/*
- * Extracts the storageEngine bson from the CollectionOptions provided.  Loops through each
- * provided storageEngine and asks the matching registered storage engine if the
- * collection/index options are valid.  Returns an error if the collection/index options are
- * invalid.
- * If no matching registered storage engine is found, return an error.
- * Validation function 'func' must be either:
- * - &StorageEngine::Factory::validateCollectionStorageOptions; or
- * - &StorageEngine::Factory::validateIndexStorageOptions
- */
-Status validateStorageOptions(
-    const BSONObj& storageEngineOptions,
-    stdx::function<Status(const StorageEngine::Factory* const, const BSONObj&)> validateFunc);
-
-/*
- * Returns a BSONArray containing the names of available storage engines, or an empty
- * array if there is no global ServiceContext
- */
-BSONArray storageEngineList();
-
-/*
- * Appends a the list of available storage engines to a BSONObjBuilder for reporting purposes.
- */
-void appendStorageEngineList(BSONObjBuilder* result);
-
 }  // namespace mongo
diff --git a/src/mongo/db/service_context_d.cpp b/src/mongo/db/service_context_d.cpp
index ca500ce6abe..b4595b97c98 100644
--- a/src/mongo/db/service_context_d.cpp
+++ b/src/mongo/db/service_context_d.cpp
@@ -43,7 +43,6 @@
 #include "mongo/db/storage/storage_engine_lock_file.h"
 #include "mongo/db/storage/storage_engine_metadata.h"
 #include "mongo/db/storage/storage_options.h"
-#include "mongo/db/unclean_shutdown.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/util/log.h"
 #include "mongo/util/map_util.h"
@@ -70,213 +69,6 @@ ServiceContextMongoD::ServiceContextMongoD() = default;
 
 ServiceContextMongoD::~ServiceContextMongoD() = default;
 
-void ServiceContextMongoD::createLockFile() {
-    try {
-        _lockFile.reset(new StorageEngineLockFile(storageGlobalParams.dbpath));
-    } catch (const std::exception& ex) {
-        uassert(28596,
-                str::stream() << "Unable to determine status of lock file in the data directory "
-                              << storageGlobalParams.dbpath
-                              << ": "
-                              << ex.what(),
-                false);
-    }
-    bool wasUnclean = _lockFile->createdByUncleanShutdown();
-    auto openStatus = _lockFile->open();
-    if (storageGlobalParams.readOnly && openStatus == ErrorCodes::IllegalOperation) {
-        _lockFile.reset();
-    } else {
-        uassertStatusOK(openStatus);
-    }
-
-    if (wasUnclean) {
-        if (storageGlobalParams.readOnly) {
-            severe() << "Attempted to open dbpath in readOnly mode, but the server was "
-                        "previously not shut down cleanly.";
-            fassertFailedNoTrace(34416);
-        }
-        warning() << "Detected unclean shutdown - " << _lockFile->getFilespec() << " is not empty.";
-        startingAfterUncleanShutdown(this) = true;
-    }
-}
-
-void ServiceContextMongoD::initializeGlobalStorageEngine() {
-    // This should be set once.
-    invariant(!getStorageEngine());
-
-    // We should have a _lockFile or be in read-only mode. Confusingly, we can still have a lockFile
-    // if we are in read-only mode. This can happen if the server is started in read-only mode on a
-    // writable dbpath.
-    invariant(_lockFile || storageGlobalParams.readOnly);
-
-    const std::string dbpath = storageGlobalParams.dbpath;
-    if (auto existingStorageEngine = StorageEngineMetadata::getStorageEngineForPath(dbpath)) {
-        if (*existingStorageEngine == "mmapv1" ||
-            (storageGlobalParams.engineSetByUser && storageGlobalParams.engine == "mmapv1")) {
-            log() << startupWarningsLog;
-            log() << "** WARNING: Support for MMAPV1 storage engine has been deprecated and will be"
-                  << startupWarningsLog;
-            log() << "**          removed in version 4.2. Please plan to migrate to the wiredTiger"
-                  << startupWarningsLog;
-            log() << "**          storage engine." << startupWarningsLog;
-            log() << "**          See http://dochub.mongodb.org/core/deprecated-mmapv1";
-            log() << startupWarningsLog;
-        }
-
-        if (storageGlobalParams.engineSetByUser) {
-            // Verify that the name of the user-supplied storage engine matches the contents of
-            // the metadata file.
-            const StorageEngine::Factory* factory =
-                mapFindWithDefault(_storageFactories,
-                                   storageGlobalParams.engine,
-                                   static_cast<const StorageEngine::Factory*>(nullptr));
-
-            if (factory) {
-                uassert(28662,
-                        str::stream() << "Cannot start server. Detected data files in " << dbpath
-                                      << " created by"
-                                      << " the '"
-                                      << *existingStorageEngine
-                                      << "' storage engine, but the"
-                                      << " specified storage engine was '"
-                                      << factory->getCanonicalName()
-                                      << "'.",
-                        factory->getCanonicalName() == *existingStorageEngine);
-            }
-        } else {
-            // Otherwise set the active storage engine as the contents of the metadata file.
-            log() << "Detected data files in " << dbpath << " created by the '"
-                  << *existingStorageEngine << "' storage engine, so setting the active"
-                  << " storage engine to '" << *existingStorageEngine << "'.";
-            storageGlobalParams.engine = *existingStorageEngine;
-        }
-    } else if (!storageGlobalParams.engineSetByUser) {
-        // Ensure the default storage engine is available with this build of mongod.
-        uassert(28663,
-                str::stream()
-                    << "Cannot start server. The default storage engine '"
-                    << storageGlobalParams.engine
-                    << "' is not available with this build of mongod. Please specify a different"
-                    << " storage engine explicitly, e.g. --storageEngine=mmapv1.",
-                isRegisteredStorageEngine(storageGlobalParams.engine));
-    } else if (storageGlobalParams.engineSetByUser && storageGlobalParams.engine == "mmapv1") {
-        log() << startupWarningsLog;
-        log() << "** WARNING: You have explicitly specified 'MMAPV1' storage engine in your"
-              << startupWarningsLog;
-        log() << "**          config file or as a command line option.  Support for the MMAPV1"
-              << startupWarningsLog;
-        log() << "**          storage engine has been deprecated and will be removed in"
-              << startupWarningsLog;
-        log() << "**          version 4.2. See http://dochub.mongodb.org/core/deprecated-mmapv1";
-        log() << startupWarningsLog;
-    }
-
-    const std::string repairpath = storageGlobalParams.repairpath;
-    uassert(40311,
-            str::stream() << "Cannot start server. The command line option '--repairpath'"
-                          << " is only supported by the mmapv1 storage engine",
-            repairpath.empty() || repairpath == dbpath || storageGlobalParams.engine == "mmapv1");
-
-    const StorageEngine::Factory* factory = _storageFactories[storageGlobalParams.engine];
-
-    uassert(18656,
-            str::stream() << "Cannot start server with an unknown storage engine: "
-                          << storageGlobalParams.engine,
-            factory);
-
-    if (storageGlobalParams.readOnly) {
-        uassert(34368,
-                str::stream()
-                    << "Server was started in read-only mode, but the configured storage engine, "
-                    << storageGlobalParams.engine
-                    << ", does not support read-only operation",
-                factory->supportsReadOnly());
-    }
-
-    std::unique_ptr<StorageEngineMetadata> metadata = StorageEngineMetadata::forPath(dbpath);
-
-    if (storageGlobalParams.readOnly) {
-        uassert(34415,
-                "Server was started in read-only mode, but the storage metadata file was not"
-                " found.",
-                metadata.get());
-    }
-
-    // Validate options in metadata against current startup options.
-    if (metadata.get()) {
-        uassertStatusOK(factory->validateMetadata(*metadata, storageGlobalParams));
-    }
-
-    ScopeGuard guard = MakeGuard([&] {
-        if (_lockFile) {
-            _lockFile->close();
-        }
-    });
-
-    setStorageEngine(
-        std::unique_ptr<StorageEngine>(factory->create(storageGlobalParams, _lockFile.get())));
-    getStorageEngine()->finishInit();
-
-    if (_lockFile) {
-        uassertStatusOK(_lockFile->writePid());
-    }
-
-    // Write a new metadata file if it is not present.
-    if (!metadata.get()) {
-        invariant(!storageGlobalParams.readOnly);
-        metadata.reset(new StorageEngineMetadata(storageGlobalParams.dbpath));
-        metadata->setStorageEngine(factory->getCanonicalName().toString());
-        metadata->setStorageEngineOptions(factory->createMetadataOptions(storageGlobalParams));
-        uassertStatusOK(metadata->write());
-    }
-
-    guard.Dismiss();
-
-    _supportsDocLocking = getStorageEngine()->supportsDocLocking();
-}
-
-void ServiceContextMongoD::shutdownGlobalStorageEngineCleanly() {
-    invariant(getStorageEngine());
-    getStorageEngine()->cleanShutdown();
-    if (_lockFile) {
-        _lockFile->clearPidAndUnlock();
-    }
-}
-
-void ServiceContextMongoD::registerStorageEngine(const std::string& name,
-                                                 const StorageEngine::Factory* factory) {
-    // No double-registering.
-    invariant(0 == _storageFactories.count(name));
-
-    // Some sanity checks: the factory must exist,
-    invariant(factory);
-
-    // and all factories should be added before we pick a storage engine.
-    invariant(!getStorageEngine());
-
-    _storageFactories[name] = factory;
-}
-
-bool ServiceContextMongoD::isRegisteredStorageEngine(const std::string& name) {
-    return _storageFactories.count(name);
-}
-
-StorageFactoriesIterator* ServiceContextMongoD::makeStorageFactoriesIterator() {
-    return new StorageFactoriesIteratorMongoD(_storageFactories.begin(), _storageFactories.end());
-}
-
-StorageFactoriesIteratorMongoD::StorageFactoriesIteratorMongoD(const FactoryMapIterator& begin,
-                                                               const FactoryMapIterator& end)
-    : _curr(begin), _end(end) {}
-
-bool StorageFactoriesIteratorMongoD::more() const {
-    return _curr != _end;
-}
-
-const StorageEngine::Factory* StorageFactoriesIteratorMongoD::next() {
-    return _curr++->second;
-}
-
 std::unique_ptr<OperationContext> ServiceContextMongoD::_newOpCtx(Client* client, unsigned opId) {
     invariant(&cc() == client);
     auto opCtx = stdx::make_unique<OperationContext>(client, opId);
diff --git a/src/mongo/db/service_context_d.h b/src/mongo/db/service_context_d.h
index 9074cb07e51..dfab1926390 100644
--- a/src/mongo/db/service_context_d.h
+++ b/src/mongo/db/service_context_d.h
@@ -28,8 +28,6 @@
 
 #pragma once
 
-#include <map>
-
 #include "mongo/db/service_context.h"
 
 namespace mongo {
@@ -39,46 +37,12 @@ class StorageEngineLockFile;
 
 class ServiceContextMongoD final : public ServiceContext {
 public:
-    using FactoryMap = std::map<std::string, const StorageEngine::Factory*>;
-
     ServiceContextMongoD();
 
     ~ServiceContextMongoD();
 
-    void createLockFile();
-
-    void initializeGlobalStorageEngine() override;
-
-    void shutdownGlobalStorageEngineCleanly() override;
-
-    void registerStorageEngine(const std::string& name,
-                               const StorageEngine::Factory* factory) override;
-
-    bool isRegisteredStorageEngine(const std::string& name) override;
-
-    StorageFactoriesIterator* makeStorageFactoriesIterator() override;
-
 private:
     std::unique_ptr<OperationContext> _newOpCtx(Client* client, unsigned opId) override;
-
-    std::unique_ptr<StorageEngineLockFile> _lockFile;
-
-    // All possible storage engines are registered here through MONGO_INIT.
-    FactoryMap _storageFactories;
-};
-
-class StorageFactoriesIteratorMongoD final : public StorageFactoriesIterator {
-public:
-    typedef ServiceContextMongoD::FactoryMap::const_iterator FactoryMapIterator;
-
-    StorageFactoriesIteratorMongoD(const FactoryMapIterator& begin, const FactoryMapIterator& end);
-
-    bool more() const override;
-    const StorageEngine::Factory* next() override;
-
-private:
-    FactoryMapIterator _curr;
-    FactoryMapIterator _end;
 };
 
 }  // namespace mongo
diff --git a/src/mongo/db/service_context_d_test_fixture.cpp b/src/mongo/db/service_context_d_test_fixture.cpp
index 1b51ac9e966..db0b6bbee7b 100644
--- a/src/mongo/db/service_context_d_test_fixture.cpp
+++ b/src/mongo/db/service_context_d_test_fixture.cpp
@@ -42,6 +42,7 @@
 #include "mongo/db/op_observer_noop.h"
 #include "mongo/db/op_observer_registry.h"
 #include "mongo/db/service_context_d.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_options.h"
 #include "mongo/stdx/memory.h"
 #include "mongo/unittest/temp_dir.h"
@@ -67,8 +68,8 @@ void ServiceContextMongoDTest::setUp() {
         storageGlobalParams.engine = "ephemeralForTest";
         storageGlobalParams.engineSetByUser = true;
 
-        checked_cast<ServiceContextMongoD*>(serviceContext)->createLockFile();
-        serviceContext->initializeGlobalStorageEngine();
+        createLockFile(serviceContext);
+        initializeStorageEngine(serviceContext);
         serviceContext->setOpObserver(stdx::make_unique<OpObserverNoop>());
     }
 
diff --git a/src/mongo/db/service_context_noop.cpp b/src/mongo/db/service_context_noop.cpp
index 59d0e696fb6..e2cc4b7d41e 100644
--- a/src/mongo/db/service_context_noop.cpp
+++ b/src/mongo/db/service_context_noop.cpp
@@ -35,33 +35,6 @@
 
 namespace mongo {
 
-void ServiceContextNoop::initializeGlobalStorageEngine() {}
-
-void ServiceContextNoop::shutdownGlobalStorageEngineCleanly() {}
-
-void ServiceContextNoop::registerStorageEngine(const std::string& name,
-                                               const StorageEngine::Factory* factory) {
-    // Takes ownership of 'factory' and deletes it because we don't need it.
-    delete factory;
-}
-
-bool ServiceContextNoop::isRegisteredStorageEngine(const std::string& name) {
-    return false;
-}
-
-StorageFactoriesIterator* ServiceContextNoop::makeStorageFactoriesIterator() {
-    class EmptySFI : public StorageFactoriesIterator {
-    public:
-        virtual bool more() const {
-            return false;
-        }
-        virtual const StorageEngine::Factory* next() {
-            MONGO_UNREACHABLE;
-        }
-    };
-    return new EmptySFI();
-}
-
 std::unique_ptr<OperationContext> ServiceContextNoop::_newOpCtx(Client* client, unsigned opId) {
     return stdx::make_unique<OperationContextNoop>(client, opId);
 }
diff --git a/src/mongo/db/service_context_noop.h b/src/mongo/db/service_context_noop.h
index 3bf4829cffe..77e8119accd 100644
--- a/src/mongo/db/service_context_noop.h
+++ b/src/mongo/db/service_context_noop.h
@@ -33,18 +33,6 @@
 namespace mongo {
 
 class ServiceContextNoop : public ServiceContext {
-public:
-    void initializeGlobalStorageEngine() override;
-
-    void shutdownGlobalStorageEngineCleanly() override;
-
-    void registerStorageEngine(const std::string& name,
-                               const StorageEngine::Factory* factory) override;
-
-    bool isRegisteredStorageEngine(const std::string& name) override;
-
-    StorageFactoriesIterator* makeStorageFactoriesIterator() override;
-
 private:
     std::unique_ptr<OperationContext> _newOpCtx(Client* client, unsigned opId) override;
 };
diff --git a/src/mongo/db/storage/SConscript b/src/mongo/db/storage/SConscript
index 95a8a6bd74e..398007c45fa 100644
--- a/src/mongo/db/storage/SConscript
+++ b/src/mongo/db/storage/SConscript
@@ -181,14 +181,30 @@ env.Library(
 env.Library(
     target='storage_engine_lock_file',
     source=[
+        'storage_engine_lock_file.cpp',
         'storage_engine_lock_file_${TARGET_OS_FAMILY}.cpp',
         ],
     LIBDEPS=[
         '$BUILD_DIR/mongo/base',
-        ]
+        '$BUILD_DIR/mongo/db/service_context',
+        ],
     )
 
 env.Library(
+    target='storage_engine_common',
+    source=[
+        'storage_engine_init.cpp'
+    ],
+    LIBDEPS=[
+    ],
+    LIBDEPS_PRIVATE=[
+        '$BUILD_DIR/mongo/db/service_context',
+        'storage_engine_lock_file',
+        'storage_engine_metadata',
+        'storage_options',
+    ],
+)
+env.Library(
     target="storage_init_d",
     source=[
         "storage_init.cpp",
diff --git a/src/mongo/db/storage/devnull/SConscript b/src/mongo/db/storage/devnull/SConscript
index 564ec403783..1d960936a60 100644
--- a/src/mongo/db/storage/devnull/SConscript
+++ b/src/mongo/db/storage/devnull/SConscript
@@ -24,4 +24,7 @@ env.Library(
         'storage_devnull_core',
         '$BUILD_DIR/mongo/db/storage/kv/kv_engine',
     ],
+    LIBDEPS_PRIVATE=[
+        '$BUILD_DIR/mongo/db/storage/storage_engine_common',
+    ],
 )
diff --git a/src/mongo/db/storage/devnull/devnull_init.cpp b/src/mongo/db/storage/devnull/devnull_init.cpp
index c3df87cda3e..68e80902d29 100644
--- a/src/mongo/db/storage/devnull/devnull_init.cpp
+++ b/src/mongo/db/storage/devnull/devnull_init.cpp
@@ -34,6 +34,7 @@
 #include "mongo/db/service_context_d.h"
 #include "mongo/db/storage/devnull/devnull_kv_engine.h"
 #include "mongo/db/storage/kv/kv_storage_engine.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_options.h"
 
 namespace mongo {
@@ -66,7 +67,8 @@ public:
 
 MONGO_INITIALIZER_WITH_PREREQUISITES(DevNullEngineInit, ("ServiceContext"))
 (InitializerContext* context) {
-    getGlobalServiceContext()->registerStorageEngine("devnull", new DevNullStorageEngineFactory());
+    registerStorageEngine(getGlobalServiceContext(),
+                          std::make_unique<DevNullStorageEngineFactory>());
     return Status::OK();
 }
-}
+}  // namespace mongo
diff --git a/src/mongo/db/storage/ephemeral_for_test/SConscript b/src/mongo/db/storage/ephemeral_for_test/SConscript
index fed440462a4..13e16746684 100644
--- a/src/mongo/db/storage/ephemeral_for_test/SConscript
+++ b/src/mongo/db/storage/ephemeral_for_test/SConscript
@@ -44,6 +44,9 @@ env.Library(
         'storage_ephemeral_for_test_core',
         '$BUILD_DIR/mongo/db/storage/kv/kv_engine'
     ],
+    LIBDEPS_PRIVATE=[
+        '$BUILD_DIR/mongo/db/storage/storage_engine_common',
+    ],
 )
 
 env.CppUnitTest(
diff --git a/src/mongo/db/storage/ephemeral_for_test/ephemeral_for_test_init.cpp b/src/mongo/db/storage/ephemeral_for_test/ephemeral_for_test_init.cpp
index 8922776255f..a4de16caf63 100644
--- a/src/mongo/db/storage/ephemeral_for_test/ephemeral_for_test_init.cpp
+++ b/src/mongo/db/storage/ephemeral_for_test/ephemeral_for_test_init.cpp
@@ -33,6 +33,7 @@
 #include "mongo/db/service_context.h"
 #include "mongo/db/storage/ephemeral_for_test/ephemeral_for_test_engine.h"
 #include "mongo/db/storage/kv/kv_storage_engine.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_options.h"
 
 namespace mongo {
@@ -72,8 +73,7 @@ public:
 
 MONGO_INITIALIZER_WITH_PREREQUISITES(EphemeralForTestEngineInit, ("ServiceContext"))
 (InitializerContext* context) {
-    getGlobalServiceContext()->registerStorageEngine("ephemeralForTest",
-                                                     new EphemeralForTestFactory());
+    registerStorageEngine(getGlobalServiceContext(), std::make_unique<EphemeralForTestFactory>());
     return Status::OK();
 }
 
diff --git a/src/mongo/db/storage/mmap_v1/SConscript b/src/mongo/db/storage/mmap_v1/SConscript
index 4d7bf2b5f87..c879be79a24 100644
--- a/src/mongo/db/storage/mmap_v1/SConscript
+++ b/src/mongo/db/storage/mmap_v1/SConscript
@@ -80,6 +80,7 @@ env.Library(
     LIBDEPS_PRIVATE=[
         '$BUILD_DIR/mongo/db/commands/server_status',
         '$BUILD_DIR/mongo/db/commands/test_commands_enabled',
+        '$BUILD_DIR/mongo/db/storage/storage_engine_common',
     ],
 )
 
diff --git a/src/mongo/db/storage/mmap_v1/mmap_v1_init.cpp b/src/mongo/db/storage/mmap_v1/mmap_v1_init.cpp
index 3bce0e22fba..42ba6cb864c 100644
--- a/src/mongo/db/storage/mmap_v1/mmap_v1_init.cpp
+++ b/src/mongo/db/storage/mmap_v1/mmap_v1_init.cpp
@@ -33,6 +33,7 @@
 #include "mongo/bson/bsonobjbuilder.h"
 #include "mongo/db/service_context.h"
 #include "mongo/db/storage/mmap_v1/mmap_v1_engine.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_engine_metadata.h"
 #include "mongo/db/storage/storage_options.h"
 
@@ -78,7 +79,7 @@ public:
 
 MONGO_INITIALIZER_WITH_PREREQUISITES(MMAPV1EngineInit, ("ServiceContext"))
 (InitializerContext* context) {
-    getGlobalServiceContext()->registerStorageEngine("mmapv1", new MMAPV1Factory());
+    registerStorageEngine(getGlobalServiceContext(), std::make_unique<MMAPV1Factory>());
     return Status::OK();
 }
 
diff --git a/src/mongo/db/storage/mmap_v1/mmap_v1_init_test.cpp b/src/mongo/db/storage/mmap_v1/mmap_v1_init_test.cpp
index 19ec450e1ac..dff7166e77a 100644
--- a/src/mongo/db/storage/mmap_v1/mmap_v1_init_test.cpp
+++ b/src/mongo/db/storage/mmap_v1/mmap_v1_init_test.cpp
@@ -31,6 +31,7 @@
 
 #include "mongo/db/json.h"
 #include "mongo/db/service_context.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_engine_metadata.h"
 #include "mongo/db/storage/storage_options.h"
 #include "mongo/unittest/unittest.h"
@@ -45,24 +46,13 @@ private:
     virtual void setUp() {
         ServiceContext* globalEnv = getGlobalServiceContext();
         ASSERT_TRUE(globalEnv);
-        ASSERT_TRUE(getGlobalServiceContext()->isRegisteredStorageEngine("mmapv1"));
-        std::unique_ptr<StorageFactoriesIterator> sfi(
-            getGlobalServiceContext()->makeStorageFactoriesIterator());
-        ASSERT_TRUE(sfi);
-        bool found = false;
-        while (sfi->more()) {
-            const StorageEngine::Factory* currentFactory = sfi->next();
-            if (currentFactory->getCanonicalName() == "mmapv1") {
-                found = true;
-                factory = currentFactory;
-                break;
-            }
-        }
-        ASSERT_TRUE(found);
+        ASSERT_TRUE(isRegisteredStorageEngine(globalEnv, "mmapv1"));
+        factory = getFactoryForStorageEngine(globalEnv, "mmapv1");
+        ASSERT_TRUE(factory);
     }
 
     virtual void tearDown() {
-        factory = NULL;
+        factory = nullptr;
     }
 
 protected:
diff --git a/src/mongo/db/storage/mobile/SConscript b/src/mongo/db/storage/mobile/SConscript
index 98ed0435228..1f481c23d0a 100644
--- a/src/mongo/db/storage/mobile/SConscript
+++ b/src/mongo/db/storage/mobile/SConscript
@@ -50,8 +50,11 @@ env.Library(
     LIBDEPS=[
         'storage_mobile_core',
         '$BUILD_DIR/mongo/db/storage/kv/kv_engine'
-        ]
-    )
+        ],
+    LIBDEPS_PRIVATE=[
+        '$BUILD_DIR/mongo/db/storage/storage_engine_common',
+    ],
+)
 '''
 env.CppUnitTest(
     target='storage_mobile_index_test',
diff --git a/src/mongo/db/storage/mobile/mobile_init.cpp b/src/mongo/db/storage/mobile/mobile_init.cpp
index edadad22887..41a5dc83159 100644
--- a/src/mongo/db/storage/mobile/mobile_init.cpp
+++ b/src/mongo/db/storage/mobile/mobile_init.cpp
@@ -34,6 +34,7 @@
 #include "mongo/db/service_context.h"
 #include "mongo/db/storage/kv/kv_storage_engine.h"
 #include "mongo/db/storage/mobile/mobile_kv_engine.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_options.h"
 
 namespace mongo {
@@ -74,7 +75,7 @@ GlobalInitializerRegisterer mobileKVEngineInitializer(
     "MobileKVEngineInit",
     {"ServiceContext"},
     [](InitializerContext* context) {
-        getGlobalServiceContext()->registerStorageEngine("mobile", new MobileFactory());
+        registerStorageEngine(getGlobalServiceContext(), std::make_unique<MobileFactory>());
         return Status::OK();
     },
     [](DeinitializerContext* const) { return Status::OK(); });
diff --git a/src/mongo/db/storage/storage_engine_init.cpp b/src/mongo/db/storage/storage_engine_init.cpp
new file mode 100644
index 00000000000..24a0b790972
--- /dev/null
+++ b/src/mongo/db/storage/storage_engine_init.cpp
@@ -0,0 +1,308 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/storage/storage_engine_init.h"
+
+#include <map>
+
+#include "mongo/bson/bsonobjbuilder.h"
+#include "mongo/db/storage/storage_engine_lock_file.h"
+#include "mongo/db/storage/storage_engine_metadata.h"
+#include "mongo/db/storage/storage_options.h"
+#include "mongo/db/unclean_shutdown.h"
+#include "mongo/util/assert_util.h"
+#include "mongo/util/log.h"
+#include "mongo/util/mongoutils/str.h"
+
+namespace mongo {
+
+extern bool _supportsDocLocking;
+
+void initializeStorageEngine(ServiceContext* service) {
+    // This should be set once.
+    invariant(!service->getStorageEngine());
+
+    // We should have a lock file or be in read-only mode. Confusingly, we can still have a lockFile
+    // if we are in read-only mode. This can happen if the server is started in read-only mode on a
+    // writable dbpath.
+    invariant(StorageEngineLockFile::get(service) || storageGlobalParams.readOnly);
+
+    const std::string dbpath = storageGlobalParams.dbpath;
+    if (auto existingStorageEngine = StorageEngineMetadata::getStorageEngineForPath(dbpath)) {
+        if (*existingStorageEngine == "mmapv1" ||
+            (storageGlobalParams.engineSetByUser && storageGlobalParams.engine == "mmapv1")) {
+            log() << startupWarningsLog;
+            log() << "** WARNING: Support for MMAPV1 storage engine has been deprecated and will be"
+                  << startupWarningsLog;
+            log() << "**          removed in version 4.2. Please plan to migrate to the wiredTiger"
+                  << startupWarningsLog;
+            log() << "**          storage engine." << startupWarningsLog;
+            log() << "**          See http://dochub.mongodb.org/core/deprecated-mmapv1";
+            log() << startupWarningsLog;
+        }
+
+        if (storageGlobalParams.engineSetByUser) {
+            // Verify that the name of the user-supplied storage engine matches the contents of
+            // the metadata file.
+            const StorageEngine::Factory* factory =
+                getFactoryForStorageEngine(service, storageGlobalParams.engine);
+            if (factory) {
+                uassert(28662,
+                        str::stream() << "Cannot start server. Detected data files in " << dbpath
+                                      << " created by"
+                                      << " the '"
+                                      << *existingStorageEngine
+                                      << "' storage engine, but the"
+                                      << " specified storage engine was '"
+                                      << factory->getCanonicalName()
+                                      << "'.",
+                        factory->getCanonicalName() == *existingStorageEngine);
+            }
+        } else {
+            // Otherwise set the active storage engine as the contents of the metadata file.
+            log() << "Detected data files in " << dbpath << " created by the '"
+                  << *existingStorageEngine << "' storage engine, so setting the active"
+                  << " storage engine to '" << *existingStorageEngine << "'.";
+            storageGlobalParams.engine = *existingStorageEngine;
+        }
+    } else if (!storageGlobalParams.engineSetByUser) {
+        // Ensure the default storage engine is available with this build of mongod.
+        uassert(28663,
+                str::stream()
+                    << "Cannot start server. The default storage engine '"
+                    << storageGlobalParams.engine
+                    << "' is not available with this build of mongod. Please specify a different"
+                    << " storage engine explicitly, e.g. --storageEngine=mmapv1.",
+                isRegisteredStorageEngine(service, storageGlobalParams.engine));
+    } else if (storageGlobalParams.engineSetByUser && storageGlobalParams.engine == "mmapv1") {
+        log() << startupWarningsLog;
+        log() << "** WARNING: You have explicitly specified 'MMAPV1' storage engine in your"
+              << startupWarningsLog;
+        log() << "**          config file or as a command line option.  Support for the MMAPV1"
+              << startupWarningsLog;
+        log() << "**          storage engine has been deprecated and will be removed in"
+              << startupWarningsLog;
+        log() << "**          version 4.2. See http://dochub.mongodb.org/core/deprecated-mmapv1";
+        log() << startupWarningsLog;
+    }
+
+    const std::string repairpath = storageGlobalParams.repairpath;
+    uassert(40311,
+            str::stream() << "Cannot start server. The command line option '--repairpath'"
+                          << " is only supported by the mmapv1 storage engine",
+            repairpath.empty() || repairpath == dbpath || storageGlobalParams.engine == "mmapv1");
+
+    const StorageEngine::Factory* factory =
+        getFactoryForStorageEngine(service, storageGlobalParams.engine);
+
+    uassert(18656,
+            str::stream() << "Cannot start server with an unknown storage engine: "
+                          << storageGlobalParams.engine,
+            factory);
+
+    if (storageGlobalParams.readOnly) {
+        uassert(34368,
+                str::stream()
+                    << "Server was started in read-only mode, but the configured storage engine, "
+                    << storageGlobalParams.engine
+                    << ", does not support read-only operation",
+                factory->supportsReadOnly());
+    }
+
+    std::unique_ptr<StorageEngineMetadata> metadata = StorageEngineMetadata::forPath(dbpath);
+
+    if (storageGlobalParams.readOnly) {
+        uassert(34415,
+                "Server was started in read-only mode, but the storage metadata file was not"
+                " found.",
+                metadata.get());
+    }
+
+    // Validate options in metadata against current startup options.
+    if (metadata.get()) {
+        uassertStatusOK(factory->validateMetadata(*metadata, storageGlobalParams));
+    }
+
+    ScopeGuard guard = MakeGuard([&] {
+        auto& lockFile = StorageEngineLockFile::get(service);
+        if (lockFile) {
+            lockFile->close();
+        }
+    });
+
+    auto& lockFile = StorageEngineLockFile::get(service);
+    service->setStorageEngine(std::unique_ptr<StorageEngine>(
+        factory->create(storageGlobalParams, lockFile ? &*lockFile : nullptr)));
+    service->getStorageEngine()->finishInit();
+
+    if (lockFile) {
+        uassertStatusOK(lockFile->writePid());
+    }
+
+    // Write a new metadata file if it is not present.
+    if (!metadata.get()) {
+        invariant(!storageGlobalParams.readOnly);
+        metadata.reset(new StorageEngineMetadata(storageGlobalParams.dbpath));
+        metadata->setStorageEngine(factory->getCanonicalName().toString());
+        metadata->setStorageEngineOptions(factory->createMetadataOptions(storageGlobalParams));
+        uassertStatusOK(metadata->write());
+    }
+
+    guard.Dismiss();
+
+    _supportsDocLocking = service->getStorageEngine()->supportsDocLocking();
+}
+
+void shutdownGlobalStorageEngineCleanly(ServiceContext* service) {
+    invariant(service->getStorageEngine());
+    service->getStorageEngine()->cleanShutdown();
+    auto& lockFile = StorageEngineLockFile::get(service);
+    if (lockFile) {
+        lockFile->clearPidAndUnlock();
+    }
+}
+
+void createLockFile(ServiceContext* service) {
+    auto& lockFile = StorageEngineLockFile::get(service);
+    try {
+        lockFile.emplace(storageGlobalParams.dbpath);
+    } catch (const std::exception& ex) {
+        uassert(28596,
+                str::stream() << "Unable to determine status of lock file in the data directory "
+                              << storageGlobalParams.dbpath
+                              << ": "
+                              << ex.what(),
+                false);
+    }
+    const bool wasUnclean = lockFile->createdByUncleanShutdown();
+    const auto openStatus = lockFile->open();
+    if (storageGlobalParams.readOnly && openStatus == ErrorCodes::IllegalOperation) {
+        lockFile = boost::none;
+    } else {
+        uassertStatusOK(openStatus);
+    }
+
+    if (wasUnclean) {
+        if (storageGlobalParams.readOnly) {
+            severe() << "Attempted to open dbpath in readOnly mode, but the server was "
+                        "previously not shut down cleanly.";
+            fassertFailedNoTrace(34416);
+        }
+        warning() << "Detected unclean shutdown - " << lockFile->getFilespec() << " is not empty.";
+        startingAfterUncleanShutdown(service) = true;
+    }
+}
+
+namespace {
+
+using FactoryMap = std::map<std::string, std::unique_ptr<StorageEngine::Factory>>;
+
+auto storageFactories = ServiceContext::declareDecoration<FactoryMap>();
+
+}  // namespace
+
+void registerStorageEngine(ServiceContext* service,
+                           std::unique_ptr<StorageEngine::Factory> factory) {
+    // No double-registering.
+    invariant(!getFactoryForStorageEngine(service, factory->getCanonicalName()));
+
+    // Some sanity checks: the factory must exist,
+    invariant(factory);
+
+    // and all factories should be added before we pick a storage engine.
+    invariant(!service->getStorageEngine());
+
+    auto name = factory->getCanonicalName().toString();
+    storageFactories(service).emplace(name, std::move(factory));
+}
+
+bool isRegisteredStorageEngine(ServiceContext* service, StringData name) {
+    return getFactoryForStorageEngine(service, name);
+}
+
+StorageEngine::Factory* getFactoryForStorageEngine(ServiceContext* service, StringData name) {
+    const auto result = storageFactories(service).find(name.toString());
+    if (result == storageFactories(service).end()) {
+        return nullptr;
+    }
+    return result->second.get();
+}
+
+Status validateStorageOptions(
+    ServiceContext* service,
+    const BSONObj& storageEngineOptions,
+    stdx::function<Status(const StorageEngine::Factory* const, const BSONObj&)> validateFunc) {
+
+    BSONObjIterator storageIt(storageEngineOptions);
+    while (storageIt.more()) {
+        BSONElement storageElement = storageIt.next();
+        StringData storageEngineName = storageElement.fieldNameStringData();
+        if (storageElement.type() != mongo::Object) {
+            return Status(ErrorCodes::BadValue,
+                          str::stream() << "'storageEngine." << storageElement.fieldNameStringData()
+                                        << "' has to be an embedded document.");
+        }
+
+        if (auto factory = getFactoryForStorageEngine(service, storageEngineName)) {
+            Status status = validateFunc(factory, storageElement.Obj());
+            if (!status.isOK()) {
+                return status;
+            }
+        } else {
+            return Status(ErrorCodes::InvalidOptions,
+                          str::stream() << storageEngineName
+                                        << " is not a registered storage engine for this server");
+        }
+    }
+    return Status::OK();
+}
+
+namespace {
+BSONArray storageEngineList(ServiceContext* service) {
+    if (!service)
+        return BSONArray();
+
+    BSONArrayBuilder engineArrayBuilder;
+
+    for (const auto& nameAndFactory : storageFactories(service)) {
+        engineArrayBuilder.append(nameAndFactory.first);
+    }
+
+    return engineArrayBuilder.arr();
+}
+}  // namespace
+
+void appendStorageEngineList(ServiceContext* service, BSONObjBuilder* result) {
+    result->append("storageEngines", storageEngineList(service));
+}
+
+}  // namespace mongo
diff --git a/src/mongo/db/storage/storage_engine_init.h b/src/mongo/db/storage/storage_engine_init.h
new file mode 100644
index 00000000000..161cc4558b9
--- /dev/null
+++ b/src/mongo/db/storage/storage_engine_init.h
@@ -0,0 +1,93 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#pragma once
+
+#include <memory>
+
+#include "mongo/base/string_data.h"
+#include "mongo/db/service_context.h"
+#include "mongo/db/storage/storage_engine.h"
+
+namespace mongo {
+
+/**
+ * Initializes the storage engine on "service".
+ */
+void initializeStorageEngine(ServiceContext* service);
+
+/**
+ * Shuts down storage engine cleanly and releases any locks on mongod.lock.
+ */
+void shutdownGlobalStorageEngineCleanly(ServiceContext* service);
+
+/**
+ * Creates the lock file used to prevent concurrent processes from accessing the data files,
+ * as appropriate.
+ */
+void createLockFile(ServiceContext* service);
+
+/**
+ * Registers a storage engine onto the given "service".
+ */
+void registerStorageEngine(ServiceContext* service,
+                           std::unique_ptr<StorageEngine::Factory> factory);
+
+/**
+ * Returns true if "name" refers to a registered storage engine.
+ */
+bool isRegisteredStorageEngine(ServiceContext* service, StringData name);
+
+/**
+ * Returns an unowned pointer to the factory for the named storage engine, or nullptr.
+ *
+ * NOTE: Exposed only for use in legacy testing scenarios.
+ */
+StorageEngine::Factory* getFactoryForStorageEngine(ServiceContext* context, StringData name);
+
+/*
+ * Extracts the storageEngine bson from the CollectionOptions provided.  Loops through each
+ * provided storageEngine and asks the matching registered storage engine if the
+ * collection/index options are valid.  Returns an error if the collection/index options are
+ * invalid.
+ * If no matching registered storage engine is found, return an error.
+ * Validation function 'func' must be either:
+ * - &StorageEngine::Factory::validateCollectionStorageOptions; or
+ * - &StorageEngine::Factory::validateIndexStorageOptions
+ */
+Status validateStorageOptions(
+    ServiceContext* service,
+    const BSONObj& storageEngineOptions,
+    stdx::function<Status(const StorageEngine::Factory* const, const BSONObj&)> validateFunc);
+
+/*
+ * Appends a the list of available storage engines to a BSONObjBuilder for reporting purposes.
+ */
+void appendStorageEngineList(ServiceContext* service, BSONObjBuilder* result);
+
+}  // namespace mongo
diff --git a/src/mongo/db/storage/storage_engine_lock_file.cpp b/src/mongo/db/storage/storage_engine_lock_file.cpp
new file mode 100644
index 00000000000..56b0bde2442
--- /dev/null
+++ b/src/mongo/db/storage/storage_engine_lock_file.cpp
@@ -0,0 +1,46 @@
+/**
+ *    Copyright (C) 2018 MongoDB Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/storage/storage_engine_lock_file.h"
+
+namespace mongo {
+namespace {
+
+auto getLockFile = ServiceContext::declareDecoration<boost::optional<StorageEngineLockFile>>();
+
+}  // namespace
+
+boost::optional<StorageEngineLockFile>& StorageEngineLockFile::get(ServiceContext* service) {
+    return getLockFile(service);
+}
+
+}  // namespace mongo
diff --git a/src/mongo/db/storage/storage_engine_lock_file.h b/src/mongo/db/storage/storage_engine_lock_file.h
index 24e2359396e..b65364bc65e 100644
--- a/src/mongo/db/storage/storage_engine_lock_file.h
+++ b/src/mongo/db/storage/storage_engine_lock_file.h
@@ -28,11 +28,13 @@
 
 #pragma once
 
+#include <boost/optional.hpp>
 #include <memory>
 #include <string>
 
 #include "mongo/base/disallow_copying.h"
 #include "mongo/base/status.h"
+#include "mongo/db/service_context.h"
 
 namespace mongo {
 
@@ -40,6 +42,8 @@ class StorageEngineLockFile {
     MONGO_DISALLOW_COPYING(StorageEngineLockFile);
 
 public:
+    static boost::optional<StorageEngineLockFile>& get(ServiceContext* service);
+
     /**
      * Checks existing lock file, if present, to see if it contains data from a previous
      * unclean shutdown. A clean shutdown should have produced a zero length lock file.
diff --git a/src/mongo/db/storage/wiredtiger/SConscript b/src/mongo/db/storage/wiredtiger/SConscript
index 826ff227314..142a108aaa7 100644
--- a/src/mongo/db/storage/wiredtiger/SConscript
+++ b/src/mongo/db/storage/wiredtiger/SConscript
@@ -102,6 +102,7 @@ if wiredtiger:
         LIBDEPS_PRIVATE=[
             '$BUILD_DIR/mongo/db/commands/server_status',
             '$BUILD_DIR/mongo/db/concurrency/lock_manager',
+            '$BUILD_DIR/mongo/db/storage/storage_engine_common',
         ],
     )
 
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_init.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_init.cpp
index 26ce1200659..9408642b210 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_init.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_init.cpp
@@ -41,6 +41,7 @@
 #include "mongo/db/service_context.h"
 #include "mongo/db/service_context_d.h"
 #include "mongo/db/storage/kv/kv_storage_engine.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_engine_lock_file.h"
 #include "mongo/db/storage/storage_engine_metadata.h"
 #include "mongo/db/storage/storage_options.h"
@@ -182,9 +183,7 @@ public:
 
 MONGO_INITIALIZER_WITH_PREREQUISITES(WiredTigerEngineInit, ("ServiceContext"))
 (InitializerContext* context) {
-    getGlobalServiceContext()->registerStorageEngine(kWiredTigerEngineName,
-                                                     new WiredTigerFactory());
-
+    registerStorageEngine(getGlobalServiceContext(), std::make_unique<WiredTigerFactory>());
     return Status::OK();
 }
 }
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_init_test.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_init_test.cpp
index a2830efebfd..164d52013dd 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_init_test.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_init_test.cpp
@@ -31,6 +31,7 @@
 
 #include "mongo/db/json.h"
 #include "mongo/db/service_context.h"
+#include "mongo/db/storage/storage_engine_init.h"
 #include "mongo/db/storage/storage_engine_metadata.h"
 #include "mongo/db/storage/storage_options.h"
 #include "mongo/db/storage/wiredtiger/wiredtiger_global_options.h"
@@ -47,27 +48,15 @@ private:
     virtual void setUp() {
         ServiceContext* globalEnv = getGlobalServiceContext();
         ASSERT_TRUE(globalEnv);
-        ASSERT_TRUE(getGlobalServiceContext()->isRegisteredStorageEngine(kWiredTigerEngineName));
-        std::unique_ptr<StorageFactoriesIterator> sfi(
-            getGlobalServiceContext()->makeStorageFactoriesIterator());
-        ASSERT_TRUE(sfi);
-        bool found = false;
-        while (sfi->more()) {
-            const StorageEngine::Factory* currentFactory = sfi->next();
-            if (currentFactory->getCanonicalName() == kWiredTigerEngineName) {
-                found = true;
-                factory = currentFactory;
-                break;
-            }
-            found = true;
-        }
-        ASSERT_TRUE(found);
+        ASSERT_TRUE(isRegisteredStorageEngine(globalEnv, kWiredTigerEngineName));
+        factory = getFactoryForStorageEngine(globalEnv, kWiredTigerEngineName);
+        ASSERT_TRUE(factory);
         _oldOptions = wiredTigerGlobalOptions;
     }
 
     virtual void tearDown() {
         wiredTigerGlobalOptions = _oldOptions;
-        factory = NULL;
+        factory = nullptr;
     }
 
     WiredTigerGlobalOptions _oldOptions;