SERVER-16567 added StorageEngineMetadata support for optional storage engine BSON document

1 files changed, 55 insertions, 10 deletions

diff --git a/src/mongo/db/storage/storage_engine_metadata.cpp b/src/mongo/db/storage/storage_engine_metadata.cpp
index b83cfa3ce8e..8360418f112 100644
--- a/src/mongo/db/storage/storage_engine_metadata.cpp
+++ b/src/mongo/db/storage/storage_engine_metadata.cpp
@@ -1,5 +1,3 @@
-// storage_engine_metadata.cpp
-
 /**
  *    Copyright (C) 2014 MongoDB Inc.
  *
@@ -64,14 +62,17 @@ namespace {
 }  // namespace
 
     // static
-    void StorageEngineMetadata::validate(const std::string& dbpath,
-                                         const std::string& storageEngine) {
+    std::auto_ptr<StorageEngineMetadata> StorageEngineMetadata::validate(
+        const std::string& dbpath,
+        const std::string& storageEngine) {
+
+        std::auto_ptr<StorageEngineMetadata> metadata;
         std::string previousStorageEngine;
         if (boost::filesystem::exists(boost::filesystem::path(dbpath) / kMetadataBasename)) {
-            StorageEngineMetadata metadata(dbpath);
-            Status status = metadata.read();
+            metadata.reset(new StorageEngineMetadata(dbpath));
+            Status status = metadata->read();
             if (status.isOK()) {
-                previousStorageEngine = metadata.getStorageEngine();
+                previousStorageEngine = metadata->getStorageEngine();
             }
             else {
                 // The storage metadata file is present but there was an issue
@@ -82,12 +83,11 @@ namespace {
         }
         else if (containsMMapV1LocalNsFile(dbpath)) {
             previousStorageEngine = "mmapv1";
-
         }
         else {
             // Directory contains neither metadata nor mmapv1 files.
             // Allow validation to succeed.
-            return;
+            return metadata;
         }
 
         uassert(28574, str::stream()
@@ -95,6 +95,8 @@ namespace {
             << " created by storage engine '" << previousStorageEngine
             << "'. The configured storage engine is '" << storageEngine << "'.",
             previousStorageEngine == storageEngine);
+
+        return metadata;
     }
 
     // static
@@ -126,16 +128,25 @@ namespace {
 
     void StorageEngineMetadata::reset() {
         _storageEngine.clear();
+        _storageEngineOptions = BSONObj();
     }
 
     const std::string& StorageEngineMetadata::getStorageEngine() const {
         return _storageEngine;
     }
 
+    const BSONObj& StorageEngineMetadata::getStorageEngineOptions() const {
+        return _storageEngineOptions;
+    }
+
     void StorageEngineMetadata::setStorageEngine(const std::string& storageEngine) {
         _storageEngine = storageEngine;
     }
 
+    void StorageEngineMetadata::setStorageEngineOptions(const BSONObj& storageEngineOptions) {
+        _storageEngineOptions = storageEngineOptions.getOwned();
+    }
+
     Status StorageEngineMetadata::read() {
         reset();
 
@@ -204,6 +215,18 @@ namespace {
                           "The 'storage.engine' field in metadata cannot be empty string.");
         }
         _storageEngine = storageEngine;
+
+        // Read storage engine options generated by storage engine factory from startup options.
+        BSONElement storageEngineOptionsElement = obj.getFieldDotted("storage.options");
+        if (!storageEngineOptionsElement.eoo()) {
+            if (!storageEngineOptionsElement.isABSONObj()) {
+                return Status(ErrorCodes::FailedToParse, str::stream()
+                              << "The 'storage.options' field in metadata must be a string: "
+                              << storageEngineOptionsElement.toString());
+            }
+            setStorageEngineOptions(storageEngineOptionsElement.Obj());
+        }
+
         return Status::OK();
     }
 
@@ -223,7 +246,8 @@ namespace {
                     << "Failed to write metadata to " << filenameTemp);
             }
 
-            BSONObj obj = BSON("storage" << BSON("engine" << _storageEngine));
+            BSONObj obj = BSON("storage"
+                << BSON("engine" << _storageEngine << "options" << _storageEngineOptions));
             ofs.write(obj.objdata(), obj.objsize());
             if (!ofs) {
                 return Status(ErrorCodes::InternalError, str::stream()
@@ -247,4 +271,25 @@ namespace {
         return Status::OK();
     }
 
+    template <>
+    Status StorageEngineMetadata::validateStorageEngineOption<bool>(const StringData& fieldName,
+                                                                    bool expectedValue) const {
+        BSONElement element = _storageEngineOptions.getField(fieldName);
+        if (element.eoo()) {
+            return Status::OK();
+        }
+        if (!element.isBoolean()) {
+            return Status(ErrorCodes::FailedToParse, str::stream()
+                << "Expected boolean field " << fieldName << " but got "
+                << typeName(element.type()) << " instead: " << element);
+        }
+        if (element.boolean() == expectedValue) {
+            return Status::OK();
+        }
+        return Status(ErrorCodes::InvalidOptions, str::stream()
+            << "Metadata contains unexpected value storage engine option for " << fieldName
+            << "Expected " << (expectedValue ? "true" : "false") << " but got "
+            << (element.boolean() ? "true" : "false") << "instead");
+    }
+
 }  // namespace mongo