Really atomic metadata

src/DataStreams/InputStreamFromASTInsertQuery.h

@@ -12,7 +12,7 @@ namespace DB
 struct BlockIO;
 class Context;
 struct StorageInMemoryMetadata;
-using StorageMetadataPtr = std::shared_ptr<StorageInMemoryMetadata>;
+using StorageMetadataPtr = std::shared_ptr<const StorageInMemoryMetadata>;
 
 /** Prepares an input stream which produce data containing in INSERT query
   * Head of inserting data could be stored in INSERT ast directly

src/Interpreters/ExpressionAnalyzer.h

@@ -32,7 +32,7 @@ class ASTSelectQuery;
 struct ASTTablesInSelectQueryElement;
 
 struct StorageInMemoryMetadata;
-using StorageMetadataPtr = std::shared_ptr<StorageInMemoryMetadata>;
+using StorageMetadataPtr = std::shared_ptr<const StorageInMemoryMetadata>;
 
 /// Create columns in block or return false if not possible
 bool sanitizeBlock(Block & block);

src/Interpreters/JoinedTables.h

@@ -14,7 +14,7 @@ class ASTSelectQuery;
 class TableJoin;
 struct SelectQueryOptions;
 struct StorageInMemoryMetadata;
-using StorageMetadataPtr = std::shared_ptr<StorageInMemoryMetadata>;
+using StorageMetadataPtr = std::shared_ptr<const StorageInMemoryMetadata>;
 
 /// Joined tables' columns resolver.
 /// We want to get each table structure at most once per table occurance. Or even better once per table.

src/Interpreters/SyntaxAnalyzer.h

@@ -17,7 +17,7 @@ struct Settings;
 struct SelectQueryOptions;
 using Scalars = std::map<String, Block>;
 struct StorageInMemoryMetadata;
-using StorageMetadataPtr = std::shared_ptr<StorageInMemoryMetadata>;
+using StorageMetadataPtr = std::shared_ptr<const StorageInMemoryMetadata>;
 
 struct SyntaxAnalyzerResult
 {

src/Storages/IStorage.h

@@ -82,7 +82,7 @@ public:
     IStorage() = delete;
     /// Storage fields should be initialized in separate methods like setColumns
     /// or setTableTTLs.
-    explicit IStorage(StorageID storage_id_) : storage_id(std::move(storage_id_)), metadata(std::make_shared<StorageInMemoryMetadata>()) {} //-V730
+    explicit IStorage(StorageID storage_id_) : storage_id(std::move(storage_id_)), metadata(std::make_unique<StorageInMemoryMetadata>()) {} //-V730
 
     virtual ~IStorage() = default;
     IStorage(const IStorage &) = delete;
@@ -137,9 +137,12 @@ public:
 
 public: /// thread-unsafe part. lockStructure must be acquired
 
-    StorageInMemoryMetadata getInMemoryMetadata() const { return *metadata; }
-    StorageMetadataPtr getInMemoryMetadataPtr() const { return metadata; }
-    void setInMemoryMetadata(const StorageInMemoryMetadata & metadata_) { metadata = std::make_shared<StorageInMemoryMetadata>(metadata_); }
+    StorageInMemoryMetadata getInMemoryMetadata() const { return *metadata.get(); }
+    StorageMetadataPtr getInMemoryMetadataPtr() const { return metadata.get(); }
+    void setInMemoryMetadata(const StorageInMemoryMetadata & metadata_)
+    {
+        metadata.set(std::make_unique<StorageInMemoryMetadata>(metadata_));
+    }
 
 
     /// Return list of virtual columns (like _part, _table, etc). In the vast
@@ -165,9 +168,7 @@ private:
     StorageID storage_id;
     mutable std::mutex id_mutex;
 
-    /// TODO (alesap) just use multiversion for atomic metadata
-    mutable std::mutex ttl_mutex;
-    StorageMetadataPtr metadata;
+    MultiVersionStorageMetadataPtr metadata;
 private:
     RWLockImpl::LockHolder tryLockTimed(
         const RWLock & rwlock, RWLockImpl::Type type, const String & query_id, const SettingSeconds & acquire_timeout) const;

src/Storages/MergeTree/MergeTreeWhereOptimizer.h

@@ -17,7 +17,7 @@ class ASTSelectQuery;
 class ASTFunction;
 class MergeTreeData;
 struct StorageInMemoryMetadata;
-using StorageMetadataPtr = std::shared_ptr<StorageInMemoryMetadata>;
+using StorageMetadataPtr = std::shared_ptr<const StorageInMemoryMetadata>;
 
 /** Identifies WHERE expressions that can be placed in PREWHERE by calculating respective
  *  sizes of columns used in particular expression and identifying "good" conditions of

src/Storages/StorageInMemoryMetadata.h

@@ -194,7 +194,7 @@ struct StorageInMemoryMetadata
     void check(const Block & block, bool need_all = false) const;
 };
 
-using StorageMetadataPtr = std::shared_ptr<StorageInMemoryMetadata>;
+using StorageMetadataPtr = std::shared_ptr<const StorageInMemoryMetadata>;
 using MultiVersionStorageMetadataPtr = MultiVersion<StorageInMemoryMetadata>;
 
 }