mirror of
https://github.com/apple/foundationdb.git
synced 2025-05-15 02:18:39 +08:00
fe81454ec2
This commit includes: - The flatbuffers implementation - A draft on how it should be used for network messages - A serializer that can be used independently What is missing: - All root objects will need a file identifier - Many special classes can not be serialized yet as the corresponding traits are not yet implemented - Object serialization can not yet be turned on (this will need a network option)
129 lines
3.2 KiB
C++
129 lines
3.2 KiB
C++
/*
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* serialize.h
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include "flow/Error.h"
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#include "flow/Arena.h"
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#include "flow/flat_buffers.h"
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template <class Ar>
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struct LoadContext {
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Ar& ar;
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std::vector<std::function<void()>> doAfter;
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LoadContext(Ar& ar) : ar(ar) {}
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Arena& arena() { return ar.arena(); }
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const uint8_t* tryReadZeroCopy(const uint8_t* ptr, unsigned len) {
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if constexpr (Ar::ownsUnderlyingMemory) {
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return ptr;
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} else {
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if (len == 0) return nullptr;
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uint8_t* dat = new (arena()) uint8_t[len];
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std::copy(ptr, ptr + len, dat);
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return dat;
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}
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}
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void done() const {
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for (auto& f : doAfter) {
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f();
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}
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}
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void addArena(Arena& arena) { arena = ar.arena(); }
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};
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template <class ReaderImpl>
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class _ObjectReader {
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public:
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template <class... Items>
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void deserialize(FileIdentifier file_identifier, Items&... items) {
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const uint8_t* data = static_cast<ReaderImpl*>(this)->data();
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LoadContext<ReaderImpl> context(*static_cast<ReaderImpl*>(this));
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ASSERT(read_file_identifier(data) == file_identifier);
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load_members(data, context, items...);
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context.done();
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}
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template <class Item>
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void deserialize(Item& item) {
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deserialize(FileIdentifierFor<Item>::value, item);
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}
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};
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class ObjectReader : public _ObjectReader<ObjectReader> {
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public:
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static constexpr bool ownsUnderlyingMemory = false;
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ObjectReader(const uint8_t* data) : _data(data) {}
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const uint8_t* data() { return _data; }
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Arena& arena() { return _arena; }
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private:
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const uint8_t* _data;
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Arena _arena;
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};
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class ArenaObjectReader : public _ObjectReader<ArenaObjectReader> {
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public:
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static constexpr bool ownsUnderlyingMemory = true;
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ArenaObjectReader(Arena const& arena, const StringRef& input) : _data(input.begin()), _arena(arena) {}
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const uint8_t* data() { return _data; }
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Arena& arena() { return _arena; }
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private:
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const uint8_t* _data;
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Arena _arena;
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};
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class ObjectWriter {
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public:
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template <class... Items>
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void serialize(FileIdentifier file_identifier, Items const&... items) {
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ASSERT(data = nullptr); // object serializer can only serialize one object
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int allocations = 0;
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auto allocator = [this, &allocations](size_t size_) {
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++allocations;
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size = size_;
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data = new uint8_t[size];
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return data;
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};
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auto res = save_members(allocator, file_identifier, items...);
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ASSERT(allocations == 1);
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}
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template <class Item>
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void serialize(Item const& item) {
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serialize(FileIdentifierFor<Item>::value, item);
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}
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StringRef toStringRef() const {
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return StringRef(data, size);
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}
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private:
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uint8_t* data = nullptr;
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int size = 0;
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};
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