hamnet70/impl/src/jsonlogger.c

// For F_SETPIPE_SZ
#define _GNU_SOURCE

#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "jsonlogger.h"

#define LOG_OR_RETURN(...) \
	if(dprintf(m_fifo_fd, __VA_ARGS__) < 0) { \
		return false; \
	}

static int m_fifo_fd = -1;
static char m_fifo_path[1024];

static bool start_message(void)
{
	if(m_fifo_fd < 0) {
		// FIFO was not opened yet. Try to open it now.
		m_fifo_fd = open(m_fifo_path, O_WRONLY | O_NONBLOCK);
		if(m_fifo_fd < 0) {
			if(errno != ENXIO) {
				perror("open");
			}
			return false;
		}
		// Increase pipe buffer to prevent/reduce EAGAIN during a JSON
		// message to prevent corrupted JSON messages. 1048576 is the
		// current maximum as permitted by the Linux kernel.
		if (fcntl(m_fifo_fd, F_SETPIPE_SZ, 1048576) < 0) {
			perror("fcntl");
		}
	}

	ssize_t ret = write(m_fifo_fd, "{", 1);
	if(ret < 0) {
		// FIFO is not writable or other error
		switch(errno) {
			case EAGAIN: // FIFO not ready for writing -> drop message
				break;

			case EPIPE: // FIFO was closed on the other side
				close(m_fifo_fd);
				m_fifo_fd = -1;
				break;

			default: // other errors are logged to stderr
				perror("write");
				break;
		}

		return false;
	}

	return true;
}

static bool end_message(void)
{
	ssize_t ret = write(m_fifo_fd, "}\n", 2);
	if(ret < 0) {
		// FIFO is not writable or other error
		if(errno != EAGAIN) {
			perror("write");
		}

		return false;
	}

	return true;
}

static bool dump_var_array_cf(const var_array_cf_t *varray)
{
	LOG_OR_RETURN("[");

	if(varray->used > 0) {
		LOG_OR_RETURN("[%g, %g]", crealf(varray->symbols[0]), cimagf(varray->symbols[0]));

		for(size_t i = 1; i < varray->used; i++) {
			LOG_OR_RETURN(", [%g, %g]", crealf(varray->symbols[i]), cimagf(varray->symbols[i]));
		}
	}

	LOG_OR_RETURN("]");

	return true;
}


bool jsonlogger_init(const char *fifoname)
{
	// try to create the named FIFO
	int ret = mkfifo(fifoname, 0666);
	if(ret < 0) {
		if(errno != EEXIST) {
			perror("mkfifo");
			return false;
		}
	}

	strncpy(m_fifo_path, fifoname, sizeof(m_fifo_path));
	m_fifo_path[sizeof(m_fifo_path)-1] = '\0';

	m_fifo_fd = -1; // open on demand

	return true;
}


void jsonlogger_shutdown(void)
{
	close(m_fifo_fd);
}


bool jsonlogger_log_simple_integer(const char *msg_type, int64_t value)
{
	if(!start_message()) {
		return false;
	}

	LOG_OR_RETURN("\"%s\": %ld", msg_type, value);

	return end_message();
}


bool jsonlogger_log_simple_double(const char *msg_type, double value)
{
	if(!start_message()) {
		return false;
	}

	LOG_OR_RETURN("\"%s\": %g", msg_type, value);

	return end_message();
}


bool jsonlogger_log_rx_stats(const rx_stats_t *rx_stats)
{
	if(!start_message()) {
		return false;
	}

	LOG_OR_RETURN("\"preambles_found\": %zd, ", rx_stats->preambles_found);
	LOG_OR_RETURN("\"successful_decodes\": %zd, ", rx_stats->successful_decodes);
	LOG_OR_RETURN("\"failed_decodes\": %zd, ", rx_stats->failed_decodes);
	LOG_OR_RETURN("\"header_errors\": %zd", rx_stats->header_errors);

	return end_message();
}


bool jsonlogger_log_rx_packet_info(const rx_packet_dbg_t *rx_packet_dbg)
{
	if(!start_message()) {
		return false;
	}

	LOG_OR_RETURN("\"preamble_symbols\": ");
	dump_var_array_cf(&rx_packet_dbg->preamble_symbols);
	LOG_OR_RETURN(", \"header_symbols\": ");
	dump_var_array_cf(&rx_packet_dbg->header_symbols);
	LOG_OR_RETURN(", \"data_symbols\": ");
	dump_var_array_cf(&rx_packet_dbg->data_symbols);
	LOG_OR_RETURN(", ");

	LOG_OR_RETURN("\"preamble_correlation_peak\": %g, ", rx_packet_dbg->preamble_correlation_peak);
	LOG_OR_RETURN("\"header_rssi_dB\": %g, ", rx_packet_dbg->header_rssi);
	LOG_OR_RETURN("\"data_rssi_dB\": %g, ", rx_packet_dbg->data_rssi);
	LOG_OR_RETURN("\"noise_floor_level_dB\": %g, ", rx_packet_dbg->noise_floor_level);

	LOG_OR_RETURN("\"carrier_tracked_freq_Hz\": %g, ", rx_packet_dbg->carrier_tracked_freq);
	LOG_OR_RETURN("\"initial_freq_offset_Hz\": %g, ", rx_packet_dbg->initial_freq_offset);
	LOG_OR_RETURN("\"final_freq_offset_Hz\": %g, ", rx_packet_dbg->final_freq_offset);

	LOG_OR_RETURN("\"header_evm\": %g, ", rx_packet_dbg->header_evm);
	LOG_OR_RETURN("\"data_evm\": %g", rx_packet_dbg->data_evm);

	return end_message();
}