libeventlog/include/eventlog.h

#ifndef _EVENTLOG_H_
#define _EVENTLOG_H_

#include <stdatomic.h>
#include <stdint.h>
#include <stddef.h>

#define EVENTLOG_DATA_MAX_SIZE (128 - 16)

#define EVENTLOG_TYPE_STRING 0

#define EVENTLOG_TRACE(event_name, ...) \
    eventlog_trace_##event_name(__VA_ARGS__)

typedef void (*event_printer_t)(const void* data, char* buf, size_t buf_size);

typedef struct {
    uint32_t id;
    const char* name;
    event_printer_t printer;
} event_def_t;

#define EVENTLOG_REGISTER_EVENT_C(event_name, print_func) \
    { .id = EVENT_ID_##event_name, .name = #event_name, .printer = print_func }

struct eventlog_entry
{
    atomic_uint_fast64_t timestamp;
    uint32_t type_id;
    uint32_t datalen;
    uint8_t data[EVENTLOG_DATA_MAX_SIZE];
};

struct eventlog_shm_header
{
    uint32_t magic;
    uint32_t version;
    atomic_uint_fast64_t tail;
    uint64_t size;
    struct eventlog_entry* entries;
};

enum eventlog_mode
{
    EVENTLOG_MODE_CREATE = 0,
    EVENTLOG_MODE_ATTACH = 1,
};

int eventlog_init(const char* path, enum eventlog_mode mode);
int eventlog_shutdown();

int eventlog_emit_event(uint64_t timestamp, const char* fmt, ...);
int eventlog_emit_event_struct(uint64_t timestamp, uint32_t type, void* data, size_t data_size);
uint64_t eventlog_get_timestamp();

int eventlog_get_snapshot(uint64_t* head, struct eventlog_entry* buffer, size_t buffer_size, size_t* actual_size);

#endif /* _EVENTLOG_H_ */