Enhance FMU Constructor for Distributed MPI Environments

[prudhomm]

Description

In distributed MPI environments, the current design of the fmu constructor in fmi4cpp leads to inefficiencies when thousands of processes simultaneously attempt to unzip an FMU file. This issue proposes an enhancement to the constructor to allow controlled unzipping.

Proposed Change

Introduce a boolean parameter in the fmu constructor to control the unzipping process. This parameter will enable one MPI process to unzip the FMU, while others wait and then directly load the library from the unzipped path.

Code Snippet

fmu::fmu(const fs::path& fmuPath, bool unzipFmu = true) {
    // Existing checks and setup
    if (unzipFmu) {
        // Current unzip logic
    } else {
        // Assume path is to unzipped FMU
        resource_ = std::make_shared<fmu_resource>(fmuPath);
        modelDescription_ = std::move(parse_model_description(resource_->model_description_path()));
    }
}

Rationale

This modification will significantly reduce the filesystem load and enhance performance in MPI-based distributed systems, where only one process needs to perform the unzipping.

Additional Context

• The communicator may not always be MPI_COMM_WORLD; it could be a subcommunicator.
• The fmu class should remain agnostic of MPI to maintain its design integrity.

Request

Kindly consider this enhancement for upcoming releases to improve fmi4cpp's suitability for large-scale parallel computing environments.