A bridge from C++ to Python logging. Inspired by pyo3_log.
This works by routing the logging calls, e.g. spdlog::info, to the Python
logging module. This is done by setting the spdlog::logger's sink to a
custom router sink. The router sink then calls the Python logging module.
For thread-safe logging, please use pybind11_log::init_mt() to initialize
the logger. For single-threaded applications, use pybind11_log::init_st().
The library is header-only, so you can just include the header file
include/pybind11_log.h in your project.
#include "pybind11_log.h"
#include <pybind11/pybind11.h>
#include <spdlog/spdlog.h>
#include <thread>
int add(int i, int j) {
spdlog::info("add({0}, {1})", i, j);
return i + j;
}
int divide(int i, int j) {
if (j == 0) {
spdlog::error("Division by zero!");
throw std::invalid_argument("Division by zero!");
} else {
spdlog::info("divide({0}, {1})", i, j);
}
return i / j;
}
void sleep_and_log() {
spdlog::info("thread: will sleep for 1s");
sleep(1);
spdlog::info("thread: sleep completed");
}
void threaded_log() {
py::gil_scoped_release release; // Release the GIL when working with threads
spdlog::info("threaded_log() starts");
std::thread t1(sleep_and_log);
t1.join();
spdlog::info("threaded_log() ends");
}
void init(const std::string& logger_name) {
pybind11_log::init_mt(logger_name);
}
PYBIND11_MODULE(pybind11_log_test, m) {
m.doc() = "pybind11_log example plugin";
m.def("init", &init, "Initialize the logger");
m.def("add", &add, "A function which adds two numbers with logging");
m.def("divide", ÷, "A function which divides two numbers with logging");
m.def("threaded_log", &threaded_log,
"A function which sleeps and log in a thread");
}You can then test that the logging works by running the following Python code:
import logging
import os
import sys
sys.path.append(os.getcwd())
from rich.logging import RichHandler
logging.basicConfig(
level="NOTSET", format="%(name)s %(message)s", datefmt="[%X]", handlers=[RichHandler()]
)
import pybind11_log_test
if __name__ == "__main__":
pybind11_log_test.init("my_fancy_logger")
pybind11_log_test.add(3, 4)
pybind11_log_test.threaded_log()
pybind11_log_test.divide(3, 0)As shown in the terminal output below, the logging calls are routed to Python
logging from the C++ code.