Cleanup and adding documentation (e290d905) · Commits · hpc / gekkofs

include/daemon/backend/metadata/db.hpp

+2 −2

Original line number	Diff line number	Diff line
		@@ -118,7 +118,7 @@ public:

		/**
		* @brief Increases only the size part of the metadata entry via a RocksDB
		* Operand.
		* Operand as part of a write operation.
		* @param key KV store key
		* @param io_size new size for entry
		* @param append
		@@ -130,7 +130,7 @@ public:

		/**
		* @brief Decreases only the size part of the metadata entry via a RocksDB
		* Operand/
		* Operand. This is used for truncate, e.g..
		* @param key KV store key
		* @param size new size for entry
		* @throws DBException on failure, NotFoundException if entry doesn't exist

include/daemon/backend/metadata/merge.hpp

+41 −4

Original line number	Diff line number	Diff line
		@@ -37,12 +37,18 @@ namespace rdb = rocksdb;

		namespace gkfs::metadata {

		/**
		* @brief Merge operator classifiers
		*/
		enum class OperandID : char {
		increase_size = 'i',
		decrease_size = 'd',
		create = 'c'
		};

		/**
		* @brief Base class for merge operands
		*/
		class MergeOperand {
		public:
		constexpr static char operand_id_suffix = ':';
		@@ -66,7 +72,9 @@ protected:
		virtual OperandID
		id() const = 0;
		};

		/**
		* @brief Increase size operand
		*/
		class IncreaseSizeOperand : public MergeOperand {
		private:
		constexpr const static char serialize_sep = ',';
		@@ -104,7 +112,9 @@ public:
		return append_;
		}
		};

		/**
		* @brief Decrease size operand
		*/
		class DecreaseSizeOperand : public MergeOperand {
		private:
		size_t size_;
		@@ -125,7 +135,9 @@ public:
		return size_;
		}
		};

		/**
		* @brief Create operand
		*/
		class CreateOperand : public MergeOperand {
		public:
		std::string metadata;
		@@ -138,24 +150,49 @@ public:
		std::string
		serialize_params() const override;
		};

		/**
		* @brief Merge operator class passed to RocksDB, used during merge operations
		*/
		class MetadataMergeOperator : public rocksdb::MergeOperator {
		public:
		~MetadataMergeOperator() override = default;

		/**
		* @brief Merges all operands in chronological order for the same key
		* @param op1 Input operand
		* @param op2 Output operand
		* @return Result of the merge operation
		*/
		bool
		FullMergeV2(const MergeOperationInput& merge_in,
		MergeOperationOutput* merge_out) const override;

		/**
		* @brief TODO functionality unclear. Currently unused.
		* @param key
		* @param operand_list
		* @param new_value
		* @param logger
		* @return
		*/
		bool
		PartialMergeMulti(const rdb::Slice& key,
		const std::deque<rdb::Slice>& operand_list,
		std::string* new_value,
		rdb::Logger* logger) const override;

		/**
		* @brief Returns the name of this Merge operator
		* @return
		*/
		const char*
		Name() const override;

		/**
		* @brief Merge Operator configuration which allows merges with just a
		* single operand.
		* @return
		*/
		bool
		AllowSingleOperand() const override;
		};

include/daemon/backend/metadata/metadata_module.hpp

+24 −2

Original line number	Diff line number	Diff line
		@@ -34,18 +34,29 @@

		namespace gkfs::metadata {

		/**
		* @brief MetadataModule is a singleton class that holds global data structures
		* for all metadata operations.
		*/
		class MetadataModule {

		private:
		MetadataModule() = default;

		std::shared_ptr<spdlog::logger> log_;
		std::shared_ptr<spdlog::logger> log_; ///< Metadata logger
		///< Map to remember and assign offsets to write append operations
		std::map<uint16_t, size_t> append_offset_reserve_{};
		std::mutex append_offset_reserve_mutex_{};
		std::mutex append_offset_reserve_mutex_{}; ///< Mutex to protect
		///< append_offset_reserve_

		public:
		///< Logger name
		static constexpr const char* LOGGER_NAME = "MetadataModule";

		/**
		* @brief Get the MetadataModule singleton instance
		* @return MetadataModule instance
		*/
		static MetadataModule*
		getInstance() {
		static MetadataModule instance;
		@@ -66,9 +77,20 @@ public:
		const std::map<uint16_t, size_t>&
		append_offset_reserve() const;

		/**
		* @brief Inserts entry into append_offset_reserve_
		* @param merge_id Merge ID
		* @param offset Offset to reserve
		*/
		void
		append_offset_reserve_put(uint16_t merge_id, size_t offset);

		/**
		* @brief Gets and erases entry from append_offset_reserve_
		* @param merge_id Merge ID
		* @return Offset reserved for merge_id
		* @throws std::out_of_range if merge_id is not in append_offset_reserve_
		*/
		size_t
		append_offset_reserve_get_and_erase(uint16_t merge_id);
		};

include/daemon/ops/metadentry.hpp

+55 −0

Original line number	Diff line number	Diff line
		@@ -34,30 +34,85 @@

		namespace gkfs::metadata {

		/**
		* @brief Returns the metadata of an object at a specific path. The metadata can
		* be of dummy values if configured
		* @param path
		* @param attr
		* @return
		*/
		Metadata
		get(const std::string& path);

		/**
		* @brief Get metadentry string only for path
		* @param path
		* @return
		*/
		std::string
		get_str(const std::string& path);

		/**
		* @brief Gets the size of a metadentry
		* @param path
		* @param ret_size (return val)
		* @return err
		*/
		size_t
		get_size(const std::string& path);

		/**
		* @brief Returns a vector of directory entries for given directory
		* @param dir
		* @return
		*/
		std::vector<std::pair<std::string, bool>>
		get_dirents(const std::string& dir);

		/**
		* @brief Returns a vector of directory entries for given directory (extended
		* version)
		* @param dir
		* @return
		*/
		std::vector<std::tuple<std::string, bool, size_t, time_t>>
		get_dirents_extended(const std::string& dir);

		/**
		* @brief Creates metadata (if required) and dentry at the same time
		* @param path
		* @param mode
		* @throws DBException
		*/
		void
		create(const std::string& path, Metadata& md);

		/**
		* @brief Update metadentry by given Metadata object and path
		* @param path
		* @param md
		*/
		void
		update(const std::string& path, Metadata& md);

		/**
		* @brief Updates a metadentry's size atomically and returns the starting offset
		* for the I/O operation.
		* @param path
		* @param io_size
		* @param offset
		* @param append
		* @return starting offset for I/O operation
		*/
		off_t
		update_size(const std::string& path, size_t io_size, off_t offset, bool append);

		/**
		* @brief Remove metadentry if exists
		* @param path
		* @return
		* @throws gkfs::metadata::DBException
		*/
		void
		remove(const std::string& path);

src/daemon/backend/metadata/db.cpp

+0 −16

Original line number	Diff line number	Diff line
		@@ -97,12 +97,6 @@ MetadataDB::~MetadataDB() {
		backend_.reset();
		}

		/**
		* Gets a KV store value for a key
		* @param key
		* @return value
		* @throws DBException on failure, NotFoundException if entry doesn't exist
		*/
		std::string
		MetadataDB::get(const std::string& key) const {
		return backend_->get(key);
		@@ -142,22 +136,12 @@ MetadataDB::update(const std::string& old_key, const std::string& new_key,
		backend_->update(old_key, new_key, val);
		}

		/**
		* @internal
		* E.g., called before a write() call
		* @endinternal
		*/
		off_t
		MetadataDB::increase_size(const std::string& key, size_t io_size, off_t offset,
		bool append) {
		return backend_->increase_size(key, io_size, offset, append);
		}

		/**
		* @internal
		* E.g., called before a truncate() call
		* @endinternal
		*/
		void
		MetadataDB::decrease_size(const std::string& key, size_t size) {
		backend_->decrease_size(key, size);