Remote FMT

Remote FMT is a C++ library to provide remote functionality to FMT. It is suitable for remote and memory efficient logging. The FMT-strings can be stored in a string catalog and are not transmitted in the logging process. This saves communication bandwidth on the communication interface.

Usage

To use this library, you can include it into your existing project by using git submodules and adding the following lines to your CMakeLists.txt:

add_subdirectory(remote_fmt)
target_link_libraries(
    ${target_name} 
    remote_fmt::remote_fmt
    remote_fmt::parser
    )

If you want to use the FetchContent feature of CMake to include the library to your project use the following lines in your CMakeLists.txt:

include(FetchContent)
FetchContent_Declare(
    remote_fmt
    GIT_REPOSITORY [email protected]:dominicpoeschko/remote_fmt.git
    GIT_TAG master
)
FetchContent_MakeAvailable(remote_fmt)
target_link_libraries(
    ${target_name} 
    remote_fmt::remote_fmt
    remote_fmt::parser
    )

Examples

To build the examples go into the examples folder and run the following commands:

mkdir build
cd build
cmake ..
make

Basic Example

The basic usage is covered in the examples/basic_usage.cpp example. This example does not explain the catalog feature set.

The example features a communication backend class which should provide at least the following functions:

struct CommunicationBackend{
    void write(std::span<std::byte const> s){}
};

After initialization the Remote FMT printer can be used to print messages through the communication backend.

printer.print("Test {}"_sc, 123);

The buffer on the remote device can be parsed with the remote_fmt::parse(...) function to print the transmitted format string. The required catalog of this function is empty in this example.

Catalog Example

Note: The catalog example only shows the behaviour of the catalog system. If you want to use the catalog feature in your project refer to the Catalog Generator Example below!

This example covers the catalog functionality in examples/catalog.cpp. Most of the example is the same as the basic example except of the catalog on the top of the example. This catalog code can be generated in the toolchain with a python script.

Another difference is the function call of the remote_fmt::parse(...) function. In this example the function is called with a catalog.

Catalog Generator Example

In this examlpe the usage of the catalog generator is covered examples/basic_usage.cpp.

To use the catalog generator you must have installed python on your computer. The generator can be called in the CMakeLists.txt of your project with the following function:

target_generate_string_constants(${target_name})

All static strings used in print functions are automatically stored in the catalog:

printer.print("Test {}"_sc, 123);

Generated Files

The python script called by CMake generates different output files. The ${target_name}_string_constants.cpp file contains the generated catalog. The file is automatically built by the python script. The script generates another file named ${target_name}_string_constants.json. This file contains the contents of the catalog in a json notation. This file can be parsed with the json file parser by nlohmann using the parseStringConstantsFromJsonFile(...) function in the catalog_helpers.hpp:

#include "remote_fmt/catalog_helpers.hpp"
auto const catalog = remote_fmt::parseStringConstantsFromJsonFile("path/to/catalog.json");