How to Serialize and Deserialize a Class with Complex Data Members in C

Introduction

Serialization involves translating an object's state into a stream of bytes that can be stored and later reconstructed back into an object with the same state. This article provides guidance on serializing and deserializing a class with members of custom data types in C , offering implementation suggestions for optimal speed, portability, and memory efficiency.

Defining the Serialization Interface

A proper serialization interface should define functions for both serializing (converting to bytes) and deserializing (reconstructing from bytes). The recommended return type for the serialize function is a vector of bytes, std::vector. The deserialize function should take a span or a stream representing the serialized bytes as input.

Example Serialization Interface:

std::vector<uint8_t> serialize(Mango const& Man);
Mango deserialize(std::span<uint8_t const> data);

Custom Data Type Serialization

For custom data types, define custom serialization functions within the namespace of those data types. For example, consider a custom data type ValType:

namespace MangoLib {
    enum class ValType : uint8_t {
        #define UseValType
        #define Line(NAME, VALUE, STRING) NAME = VALUE
        Line(void_,   0, "void"),
        Line(int_,    1, "int"),
        Line(bool_,   2, "bool"),
        Line(string_, 3, "string"),
        #undef Line
        #undef UseValType
    };
}

For this type, you would define a serialization function:

namespace MangoLib {
    template <typename Out>
    Out do_generate(Out out, ValType const& x) {
        using my_serialization_helpers::do_generate;
        return do_generate(out,
                           static_cast<std::underlying_type_t<ValType>>(x));
    }
}

Similar serialization functions should be defined for other custom data types as needed.

Implementation

The following implementation suggestions consider speed, portability, and memory efficiency:

• Byte-Order: Ensure consistent byte-order through platform-specific functions if necessary.
• Endian-Neutral: Implement serialization with a platform-neutral byte-order to ensure portability.
• Representation of Strings: Customize the serialization of strings to optimize memory and speed.
• Container Capacity: Specify a maximum supported container capacity for efficient serialization.

Memory Efficiency

To optimize memory usage during serialization:

• Avoid Pointers: Use value types or references to avoid the overhead of pointers.
• Bit Fields and Packed Structures: Consider using bit fields and packed structures to pack data tightly.
• Use Container Optimizations: Utilize optimizations such as capacity reservations and pre-allocations when using containers.

Speed and Portability

For optimal speed and portability:

• Primitive Data Types: Use specialized serialization functions for primitive data types for faster processing.
• Multiple Overloads: Provide multiple overloads of serialization functions to handle different data types efficiently.
• Header-Only Serialization: Employ header-only serialization libraries such as msgpack or cereal to avoid linking dependencies.

Additional Considerations

• Storage Format: Determine the target storage format for the serialized data (file, network, memory).
• File IO: Provide serialization functions that operate on file streams for easier storage.
• Unit Testing: Thoroughly test serialization and deserialization for accuracy and correctness.

Conclusion

This article provides detailed guidance and implementation suggestions for efficiently serializing and deserializing classes with complex data members in C . By considering speed, portability, and memory efficiency, you can develop robust serialization solutions that meet the specific requirements of your application.