File create: move exist check from client to daemon. Configuration added (c0489cc3) · Commits · David Auer / gekkofs

include/config.hpp

+4 −0

Original line number	Diff line number	Diff line
		@@ -49,6 +49,10 @@ constexpr auto use_ctime = false;
		constexpr auto use_mtime = false;
		constexpr auto use_link_cnt = false;
		constexpr auto use_blocks = false;

		// metadata logic
		// Check for existence of file metadata before create. This done on RocksDB level
		constexpr auto create_exist_check = true;
		} // namespace metadata

		namespace rpc {

include/daemon/backend/exceptions.hpp

+5 −0

Original line number	Diff line number	Diff line
		@@ -30,6 +30,11 @@ public:
		explicit NotFoundException(const std::string& s) : DBException(s) {};
		};

		class ExistsException : public DBException {
		public:
		explicit ExistsException(const std::string& s) : DBException(s) {};
		};

		} // namespace metadata
		} // namespace gkfs

include/daemon/backend/metadata/db.hpp

+3 −1

Original line number	Diff line number	Diff line
		@@ -35,12 +35,14 @@ private:
		public:
		static inline void throw_rdb_status_excpt(const rdb::Status& s);

		MetadataDB(const std::string& path);
		explicit MetadataDB(const std::string& path);

		std::string get(const std::string& key) const;

		void put(const std::string& key, const std::string& val);

		void put_if_not_exist(const std::string& key, const std::string& val);

		void remove(const std::string& key);

		bool exists(const std::string& key);

src/client/gkfs_functions.cpp

+49 −47

Original line number	Diff line number	Diff line
		@@ -114,46 +114,49 @@ int gkfs_open(const std::string& path, mode_t mode, int flags) {
		return -1;
		}

		bool exists = true;
		auto md = gkfs::util::get_metadata(path);
		if (!md) {
		if (errno == ENOENT) {
		exists = false;
		} else {
		LOG(ERROR, "Error while retriving stat to file");
		return -1;
		}
		}

		if (!exists) {
		if (!(flags & O_CREAT)) {
		// file doesn't exists and O_CREAT was not set
		errno = ENOENT;
		return -1;
		}

		/* CREATION */
		assert(flags & O_CREAT);
		// dummy metadata creation
		std::shared_ptr<gkfs::metadata::Metadata> md = nullptr;

		if (flags & O_CREAT) {
		if (flags & O_DIRECTORY) {
		LOG(ERROR, "O_DIRECTORY use with O_CREAT. NOT SUPPORTED");
		errno = ENOTSUP;
		return -1;
		}

		// no access check required here. If one is using our FS they have the permissions.
		if (gkfs_create(path, mode \| S_IFREG)) {
		LOG(ERROR, "Error creating non-existent file: '{}'", strerror(errno));
		int err = gkfs_create(path, mode \| S_IFREG);
		if (err) {
		if (errno == EEXIST) {
		// file exists, O_CREAT was set
		if (flags & O_EXCL) {
		// File exists and O_EXCL & O_CREAT was set
		errno = EEXIST;
		return -1;
		}
		// file exists, O_CREAT was set O_EXCL wasnt, so function does not fail
		// this case is actually undefined as per `man 2 open`
		md = gkfs::util::get_metadata(path);
		} else {
		/* File already exists */

		if (flags & O_EXCL) {
		// File exists and O_EXCL was set
		errno = EEXIST;
		LOG(ERROR, "Error creating file: '{}'", strerror(errno));
		return -1;
		}
		} else {
		// file was successfully created. Add to filemap
		return CTX->file_map()->add(std::make_shared<gkfs::filemap::OpenFile>(path, flags));
		}
		} else {
		md = gkfs::util::get_metadata(path);
		if (!md) {
		if (errno == ENOENT) {
		// file doesn't exists and O_CREAT was not set
		return -1;
		} else {
		LOG(ERROR, "Error stating existing file");
		return -1;
		}
		}
		}
		// file exists

		#ifdef HAS_SYMLINKS
		if (md->is_link()) {
		@@ -180,7 +183,6 @@ int gkfs_open(const std::string& path, mode_t mode, int flags) {
		return -1;
		}
		}
		}

		return CTX->file_map()->add(std::make_shared<gkfs::filemap::OpenFile>(path, flags));
		}

src/daemon/backend/metadata/db.cpp

+70 −1

Original line number	Diff line number	Diff line
		@@ -26,6 +26,10 @@ namespace gkfs {
		namespace metadata {


		/**
		* Called when the daemon is started: Connects to the KV store
		* @param path where KV store data is stored
		*/
		MetadataDB::MetadataDB(const std::string& path) : path(path) {
		// Optimize RocksDB. This is the easiest way to get RocksDB to perform well
		options.IncreaseParallelism();
		@@ -43,6 +47,12 @@ MetadataDB::MetadataDB(const std::string& path) : path(path) {
		this->db.reset(rdb_ptr);
		}

		/**
		* Exception wrapper on Status object. Throws NotFoundException if s.IsNotFound(),
		* general DBException otherwise
		* @param RocksDB status
		* @throws DBException
		*/
		void MetadataDB::throw_rdb_status_excpt(const rdb::Status& s) {
		assert(!s.ok());

		@@ -53,6 +63,12 @@ void MetadataDB::throw_rdb_status_excpt(const rdb::Status& s) {
		}
		}

		/**
		* 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 {
		std::string val;
		auto s = db->Get(rdb::ReadOptions(), key, &val);
		@@ -62,6 +78,12 @@ std::string MetadataDB::get(const std::string& key) const {
		return val;
		}

		/**
		* Puts an entry into the KV store
		* @param key
		* @param val
		* @throws DBException on failure
		*/
		void MetadataDB::put(const std::string& key, const std::string& val) {
		assert(gkfs::path::is_absolute(key));
		assert(key == "/" \|\| !gkfs::path::has_trailing_slash(key));
		@@ -73,6 +95,23 @@ void MetadataDB::put(const std::string& key, const std::string& val) {
		}
		}

		/**
		* Puts an entry into the KV store if it doesn't exist. This function does not use a mutex.
		* @param key
		* @param val
		* @throws DBException on failure, ExistException if entry already exists
		*/
		void MetadataDB::put_if_not_exist(const std::string& key, const std::string& val) {
		if (exists(key))
		throw ExistsException("");
		put(key, val);
		}

		/**
		* Removes an entry from the KV store
		* @param key
		* @throws DBException on failure, NotFoundException if entry doesn't exist
		*/
		void MetadataDB::remove(const std::string& key) {
		auto s = db->Delete(write_opts, key);
		if (!s.ok()) {
		@@ -80,6 +119,12 @@ void MetadataDB::remove(const std::string& key) {
		}
		}

		/**
		* checks for existence of an entry
		* @param key
		* @return true if exists
		* @throws DBException on failure
		*/
		bool MetadataDB::exists(const std::string& key) {
		std::string val;
		auto s = db->Get(rdb::ReadOptions(), key, &val);
		@@ -98,7 +143,7 @@ bool MetadataDB::exists(const std::string& key) {
		* @param old_key
		* @param new_key
		* @param val
		* @return
		* @throws DBException on failure, NotFoundException if entry doesn't exist
		*/
		void MetadataDB::update(const std::string& old_key, const std::string& new_key, const std::string& val) {
		//TODO use rdb::Put() method
		@@ -111,6 +156,14 @@ void MetadataDB::update(const std::string& old_key, const std::string& new_key,
		}
		}

		/**
		* Increases only the size part of the metadentry via a RocksDB Operand Operation.
		* E.g., called before a write() call
		* @param key
		* @param size
		* @param append
		* @throws DBException on failure
		*/
		void MetadataDB::increase_size(const std::string& key, size_t size, bool append) {
		auto uop = IncreaseSizeOperand(size, append);
		auto s = db->Merge(write_opts, key, uop.serialize());
		@@ -119,6 +172,13 @@ void MetadataDB::increase_size(const std::string& key, size_t size, bool append)
		}
		}

		/**
		* Decreases only the size part of the metadentry via a RocksDB Operand Operation
		* E.g., called before a truncate() call
		* @param key
		* @param size
		* @throws DBException on failure
		*/
		void MetadataDB::decrease_size(const std::string& key, size_t size) {
		auto uop = DecreaseSizeOperand(size);
		auto s = db->Merge(write_opts, key, uop.serialize());
		@@ -179,6 +239,9 @@ std::vector<std::pair<std::string, bool>> MetadataDB::get_dirents(const std::str
		return entries;
		}

		/**
		* Code example for iterating all entries in KV store. This is for debug only as it is too expensive
		*/
		void MetadataDB::iterate_all() {
		std::string key;
		std::string val;
		@@ -190,6 +253,12 @@ void MetadataDB::iterate_all() {
		}
		}

		/**
		* Called when RocksDB connection is established.
		* Used for setting KV store settings
		* see here: https://github.com/facebook/rocksdb/wiki/RocksDB-Tuning-Guide
		* @param options
		*/
		void MetadataDB::optimize_rocksdb_options(rdb::Options& options) {
		options.max_successive_merges = 128;
		}