continue os refactor, start with fs backend

src/CMakeLists.txt

@@ -21,6 +21,8 @@ add_library(fragment_store
 	#new
 	./fragment_store/object_store.hpp
 	./fragment_store/object_store.cpp
+	./fragment_store/backends/filesystem_storage.hpp
+	./fragment_store/backends/filesystem_storage.cpp
 
 	./json/message_components.hpp # TODO: move
 	./json/tox_message_components.hpp # TODO: move

src/fragment_store/backends/filesystem_storage.cpp

@@ -0,0 +1,237 @@
+#include "./filesystem_storage.hpp"
+
+#include "../meta_components.hpp"
+
+#include <nlohmann/json.hpp>
+
+#include <solanaceae/file/file2_std.hpp>
+#include <solanaceae/file/file2_mem.hpp>
+
+#include "../file2_stack.hpp"
+
+#include <filesystem>
+
+#include <iostream>
+
+static const char* metaFileTypeSuffix(MetaFileType mft) {
+	switch (mft) {
+		case MetaFileType::TEXT_JSON: return ".json";
+		//case MetaFileType::BINARY_ARB: return ".bin";
+		case MetaFileType::BINARY_MSGPACK: return ".msgpack";
+	}
+	return ""; // .unk?
+}
+
+namespace backend {
+
+FilesystemStorage::FilesystemStorage(ObjectStore2& os) : StorageBackendI::StorageBackendI(os) {
+}
+
+FilesystemStorage::~FilesystemStorage(void) {
+}
+
+bool FilesystemStorage::write(Object o, std::function<write_to_storage_fetch_data_cb>& data_cb) {
+	auto& reg = _os.registry();
+
+	if (!reg.valid(o)) {
+		return false;
+	}
+
+	ObjectHandle oh {reg, o};
+
+	if (!oh.all_of<FragComp::Ephemeral::FilePath>()) {
+		// not a file fragment?
+		return false;
+	}
+
+	// split object storage
+
+	MetaFileType meta_type = MetaFileType::TEXT_JSON; // TODO: better defaults
+	if (reg.all_of<FragComp::Ephemeral::MetaFileType>(o)) {
+		meta_type = oh.get<FragComp::Ephemeral::MetaFileType>().type;
+	}
+
+	Encryption meta_enc = Encryption::NONE; // TODO: better defaults
+	Compression meta_comp = Compression::NONE; // TODO: better defaults
+
+	if (meta_type != MetaFileType::TEXT_JSON) {
+		if (oh.all_of<FragComp::Ephemeral::MetaEncryptionType>()) {
+			meta_enc = oh.get<FragComp::Ephemeral::MetaEncryptionType>().enc;
+		}
+
+		if (oh.all_of<FragComp::Ephemeral::MetaCompressionType>()) {
+			meta_comp = oh.get<FragComp::Ephemeral::MetaCompressionType>().comp;
+		}
+	} else {
+		// we cant have encryption or compression
+		// so we force NONE for TEXT JSON
+
+		oh.emplace_or_replace<FragComp::Ephemeral::MetaEncryptionType>(Encryption::NONE);
+		oh.emplace_or_replace<FragComp::Ephemeral::MetaCompressionType>(Compression::NONE);
+	}
+
+	std::filesystem::path meta_tmp_path = oh.get<FragComp::Ephemeral::FilePath>().path + ".meta" + metaFileTypeSuffix(meta_type) + ".tmp";
+	meta_tmp_path.replace_filename("." + meta_tmp_path.filename().generic_u8string());
+	// TODO: make meta comp work with mem compressor
+	//auto meta_file_stack = buildFileStackWrite(std::string_view{meta_tmp_path.generic_u8string()}, meta_enc, meta_comp);
+	std::stack<std::unique_ptr<File2I>> meta_file_stack;
+	meta_file_stack.push(std::make_unique<File2WFile>(std::string_view{meta_tmp_path.generic_u8string()}));
+
+	if (meta_file_stack.empty()) {
+		std::cerr << "FS error: failed to create temporary meta file stack\n";
+		std::filesystem::remove(meta_tmp_path); // might have created an empty file
+		return false;
+	}
+
+	Encryption data_enc = Encryption::NONE; // TODO: better defaults
+	Compression data_comp = Compression::NONE; // TODO: better defaults
+	if (oh.all_of<FragComp::DataEncryptionType>()) {
+		data_enc = oh.get<FragComp::DataEncryptionType>().enc;
+	}
+	if (oh.all_of<FragComp::DataCompressionType>()) {
+		data_comp = oh.get<FragComp::DataCompressionType>().comp;
+	}
+
+	std::filesystem::path data_tmp_path = oh.get<FragComp::Ephemeral::FilePath>().path + ".tmp";
+	data_tmp_path.replace_filename("." + data_tmp_path.filename().generic_u8string());
+	auto data_file_stack = buildFileStackWrite(std::string_view{data_tmp_path.generic_u8string()}, data_enc, data_comp);
+	if (data_file_stack.empty()) {
+		while (!meta_file_stack.empty()) { meta_file_stack.pop(); }
+		std::filesystem::remove(meta_tmp_path);
+		std::cerr << "FS error: failed to create temporary data file stack\n";
+		return false;
+	}
+
+	try { // TODO: properly sanitize strings, so this cant throw
+		// sharing code between binary msgpack and text json for now
+		nlohmann::json meta_data_j = nlohmann::json::object(); // metadata needs to be an object, null not allowed
+		// metadata file
+
+		for (const auto& [type_id, storage] : reg.storage()) {
+			if (!storage.contains(o)) {
+				continue;
+			}
+
+			//std::cout << "storage type: type_id:" << type_id << " name:" << storage.type().name() << "\n";
+
+			// use type_id to find serializer
+			auto s_cb_it = _os._sc._serl_json.find(type_id);
+			if (s_cb_it == _os._sc._serl_json.end()) {
+				// could not find serializer, not saving
+				continue;
+			}
+
+			// noooo, why cant numbers be keys
+			//if (meta_type == MetaFileType::BINARY_MSGPACK) { // msgpack uses the hash id instead
+				//s_cb_it->second(storage.value(fid), meta_data[storage.type().hash()]);
+			//} else if (meta_type == MetaFileType::TEXT_JSON) {
+			s_cb_it->second(oh, meta_data_j[storage.type().name()]);
+			//}
+		}
+
+		if (meta_type == MetaFileType::BINARY_MSGPACK) { // binary metadata file
+			std::vector<uint8_t> binary_meta_data;
+			{
+				std::stack<std::unique_ptr<File2I>> binary_writer_stack;
+				binary_writer_stack.push(std::make_unique<File2MemW>(binary_meta_data));
+
+				if (!buildStackWrite(binary_writer_stack, meta_enc, meta_comp)) {
+					while (!meta_file_stack.empty()) { meta_file_stack.pop(); }
+					std::filesystem::remove(meta_tmp_path);
+					while (!data_file_stack.empty()) { data_file_stack.pop(); }
+					std::filesystem::remove(data_tmp_path);
+					std::cerr << "FS error: binary writer creation failed '" << oh.get<FragComp::Ephemeral::FilePath>().path << "'\n";
+					return false;
+				}
+
+				{
+					const std::vector<uint8_t> meta_data = nlohmann::json::to_msgpack(meta_data_j);
+					if (!binary_writer_stack.top()->write(ByteSpan{meta_data})) {
+						// i feel like exceptions or refactoring would be nice here
+						while (!meta_file_stack.empty()) { meta_file_stack.pop(); }
+						std::filesystem::remove(meta_tmp_path);
+						while (!data_file_stack.empty()) { data_file_stack.pop(); }
+						std::filesystem::remove(data_tmp_path);
+						std::cerr << "FS error: binary writer failed '" << oh.get<FragComp::Ephemeral::FilePath>().path << "'\n";
+						return false;
+					}
+				}
+			}
+
+			//// the meta file is itself msgpack data
+			nlohmann::json meta_header_j = nlohmann::json::array();
+			meta_header_j.emplace_back() = "SOLMET";
+			meta_header_j.push_back(meta_enc);
+			meta_header_j.push_back(meta_comp);
+
+			// with a custom msgpack impl like cmp, we can be smarter here and dont need an extra buffer
+			meta_header_j.push_back(nlohmann::json::binary(binary_meta_data));
+
+			const auto meta_header_data = nlohmann::json::to_msgpack(meta_header_j);
+			meta_file_stack.top()->write({meta_header_data.data(), meta_header_data.size()});
+		} else if (meta_type == MetaFileType::TEXT_JSON) {
+			// cant be compressed or encrypted
+			const auto meta_file_json_str = meta_data_j.dump(2, ' ', true);
+			meta_file_stack.top()->write({reinterpret_cast<const uint8_t*>(meta_file_json_str.data()), meta_file_json_str.size()});
+		}
+
+	} catch (...) {
+		while (!meta_file_stack.empty()) { meta_file_stack.pop(); } // destroy stack // TODO: maybe work with scope?
+		std::filesystem::remove(meta_tmp_path);
+		while (!data_file_stack.empty()) { data_file_stack.pop(); } // destroy stack // TODO: maybe work with scope?
+		std::filesystem::remove(data_tmp_path);
+		std::cerr << "FS error: failed to serialize json data\n";
+		return false;
+	}
+
+	// now data
+	// for zstd compression, chunk size is frame size. (no cross frame referencing)
+	// TODO: add buffering steam layer
+	static constexpr int64_t chunk_size{1024*1024}; // 1MiB should be enough
+	std::vector<uint8_t> buffer(chunk_size);
+	uint64_t buffer_actual_size {0};
+	do {
+		buffer_actual_size = data_cb(buffer.data(), buffer.size());
+		if (buffer_actual_size == 0) {
+			break;
+		}
+		if (buffer_actual_size > buffer.size()) {
+			// wtf
+			break;
+		}
+
+		data_file_stack.top()->write({buffer.data(), buffer_actual_size});
+	} while (buffer_actual_size == buffer.size());
+
+	//meta_file.flush();
+	//meta_file.close();
+	while (!meta_file_stack.empty()) { meta_file_stack.pop(); } // destroy stack // TODO: maybe work with scope?
+	//data_file.flush();
+	//data_file.close();
+	while (!data_file_stack.empty()) { data_file_stack.pop(); } // destroy stack // TODO: maybe work with scope?
+
+	std::filesystem::rename(
+		meta_tmp_path,
+		oh.get<FragComp::Ephemeral::FilePath>().path + ".meta" + metaFileTypeSuffix(meta_type)
+	);
+
+	std::filesystem::rename(
+		data_tmp_path,
+		oh.get<FragComp::Ephemeral::FilePath>().path
+	);
+
+	// TODO: check return value of renames
+
+	if (oh.all_of<FragComp::Ephemeral::DirtyTag>()) {
+		oh.remove<FragComp::Ephemeral::DirtyTag>();
+	}
+
+	return true;
+}
+
+bool FilesystemStorage::read(Object o, std::function<read_from_storage_put_data_cb>& data_cb) {
+	return false;
+}
+
+} // backend
+

src/fragment_store/backends/filesystem_storage.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "../object_store.hpp"
+
+namespace backend {
+
+struct FilesystemStorage : public StorageBackendI {
+	FilesystemStorage(ObjectStore2& os);
+	~FilesystemStorage(void);
+
+	bool write(Object o, std::function<write_to_storage_fetch_data_cb>& data_cb) override;
+	bool read(Object o, std::function<read_from_storage_put_data_cb>& data_cb) override;
+
+	//// convenience function
+	//nlohmann::json loadFromStorageNJ(FragmentID fid);
+};
+
+} // backend

src/fragment_store/object_store.cpp

@@ -6,6 +6,22 @@
 
 #include <iostream>
 
+StorageBackendI::StorageBackendI(ObjectStore2& os) : _os(os) {
+}
+
+bool StorageBackendI::write(Object o, const ByteSpan data) {
+	std::function<write_to_storage_fetch_data_cb> fn_cb = [read = 0ull, data](uint8_t* request_buffer, uint64_t buffer_size) mutable -> uint64_t {
+		uint64_t i = 0;
+		for (; i+read < data.size && i < buffer_size; i++) {
+			request_buffer[i] = data[i+read];
+		}
+		read += i;
+
+		return i;
+	};
+	return write(o, fn_cb);
+}
+
 static bool serl_json_data_enc_type(const ObjectHandle oh, nlohmann::json& out) {
 	out = static_cast<std::underlying_type_t<Encryption>>(
 		oh.get<FragComp::DataEncryptionType>().enc

src/fragment_store/object_store.hpp

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <solanaceae/util/event_provider.hpp>
+#include <solanaceae/util/span.hpp>
 
 #include "./serializer.hpp" // TODO: get rid of the tight nljson integration
 
@@ -14,6 +15,28 @@ enum class Object : uint32_t {};
 using ObjectRegistry = entt::basic_registry<Object>;
 using ObjectHandle = entt::basic_handle<ObjectRegistry>;
 
+// fwd
+struct ObjectStore2;
+
+struct StorageBackendI {
+	// OR or OS ?
+	ObjectStore2& _os;
+
+	StorageBackendI(ObjectStore2& os);
+
+	// ========== write object to storage ==========
+	using write_to_storage_fetch_data_cb = uint64_t(uint8_t* request_buffer, uint64_t buffer_size);
+	// calls data_cb with a buffer to be filled in, cb returns actual count of data. if returned < max, its the last buffer.
+	virtual bool write(Object o, std::function<write_to_storage_fetch_data_cb>& data_cb) = 0;
+	//virtual bool write(Object o, const uint8_t* data, const uint64_t data_size); // default impl
+	virtual bool write(Object o, const ByteSpan data); // default impl
+
+	// ========== read object from storage ==========
+	using read_from_storage_put_data_cb = void(const ByteSpan buffer);
+	virtual bool read(Object o, std::function<read_from_storage_put_data_cb>& data_cb) = 0;
+
+};
+
 namespace ObjectStore::Events {
 
 	struct ObjectConstruct {
@@ -54,12 +77,16 @@ struct ObjectStore2 : public ObjectStoreEventProviderI {
 
 	SerializerCallbacks<Object> _sc;
 
+	// TODO: default backend?
+
 	ObjectStore2(void);
 	virtual ~ObjectStore2(void);
 
 	ObjectRegistry& registry(void);
 	ObjectHandle objectHandle(const Object o);
 
+	// sync?
+
 	void throwEventConstruct(const Object o);
 	void throwEventUpdate(const Object o);
 	void throwEventDestroy(const Object o);