how-to-use-flatbuffers.md

How to use FlatBuffers

Flatbuffers is used to serialize and deserialize some data structures.

Schema files are used to define the data structures and are used to generate the code to serialize and deserialize the data structures.

Those files are located in the schema directory.

Code generated from the schema files is checked in to the repository, therefore you only need to generate the code if you change an existing schema file or add a new one. You can find details on how to update schema files here.

Generating code

We use flatc to generate rust code.

We recommend building flatc from source. To generate rust code, use

just gen-all-fbs-rust-code

Note about generated code

Because we invoke flatc multiple times when generating the Rust code, the mod.rs generated in ./src/hyperlight_common/src/flatbuffers is overwritten multiple times and will likely be incorrect. Make sure to manually inspect and if necessary update this file before continuing with your changes as certain modules might be missing. After fixing mod.rs, you might need to re-run just fmt, since it might not have applied to all generated files if your mod.rs was invalid.

flatc does support passing multiple schema files (e.g. it is possible to pass .\src\schema\*.fbs), so we could regenerate all the files each time a change was made, however that generates incorrect code (see here for details).