Skylight gem dynamic loading code

skylight_dlopen.c

#include "skylight_dlopen.h"
#include "dlfcn.h"

sky_main_fn sky_main = 0;
sky_init_fn sky_init = 0;
sky_hrtime_fn sky_hrtime = 0;
sky_instrumenter_new_fn sky_instrumenter_new = 0;
sky_instrumenter_start_fn sky_instrumenter_start = 0;
sky_instrumenter_stop_fn sky_instrumenter_stop = 0;
sky_instrumenter_submit_trace_fn sky_instrumenter_submit_trace = 0;
sky_instrumenter_track_desc_fn sky_instrumenter_track_desc = 0;
sky_instrumenter_free_fn sky_instrumenter_free = 0;
sky_trace_new_fn sky_trace_new = 0;
sky_trace_free_fn sky_trace_free = 0;
sky_trace_start_fn sky_trace_start = 0;
sky_trace_endpoint_fn sky_trace_endpoint = 0;
sky_trace_set_endpoint_fn sky_trace_set_endpoint = 0;
sky_trace_uuid_fn sky_trace_uuid = 0;
sky_trace_set_uuid_fn sky_trace_set_uuid = 0;
sky_trace_instrument_fn sky_trace_instrument = 0;
sky_trace_span_set_title_fn sky_trace_span_set_title = 0;
sky_trace_span_set_desc_fn sky_trace_span_set_desc = 0;
sky_lex_sql_fn sky_lex_sql = 0;
sky_trace_span_set_sql_fn sky_trace_span_set_sql = 0;
sky_trace_span_add_uint_annotation_fn sky_trace_span_add_uint_annotation = 0;
sky_trace_span_done_fn sky_trace_span_done = 0;

#define BIND_FN(SRC, DST)           \
  do {                             \
    fnptr = dlsym(SRC, #DST);       \
    if (!fnptr) {                  \
      return -1;                    \
    }                              \
    *(void**) (&DST) = fnptr;       \
  } while(0)

// Loads libskylight at the specified file location and binds the function
// pointers.
int sky_load_libskylight(const char* filename) {
    void* fnptr;
    void* libskylight;

    if (sky_init != 0) {
        return 0;
    }

    libskylight = dlopen(filename, RTLD_NOW | RTLD_LOCAL);

    if (!libskylight) {
        return -1;
    }

    BIND_FN(libskylight, sky_main);
    BIND_FN(libskylight, sky_init);
    BIND_FN(libskylight, sky_hrtime);
    BIND_FN(libskylight, sky_instrumenter_new);
    BIND_FN(libskylight, sky_instrumenter_start);
    BIND_FN(libskylight, sky_instrumenter_stop);
    BIND_FN(libskylight, sky_instrumenter_submit_trace);
    BIND_FN(libskylight, sky_instrumenter_track_desc);
    BIND_FN(libskylight, sky_instrumenter_free);
    BIND_FN(libskylight, sky_trace_new);
    BIND_FN(libskylight, sky_trace_free);
    BIND_FN(libskylight, sky_trace_start);
    BIND_FN(libskylight, sky_trace_endpoint);
    BIND_FN(libskylight, sky_trace_set_endpoint);
    BIND_FN(libskylight, sky_trace_uuid);
    BIND_FN(libskylight, sky_trace_set_uuid);
    BIND_FN(libskylight, sky_trace_instrument);
    BIND_FN(libskylight, sky_trace_span_set_title);
    BIND_FN(libskylight, sky_trace_span_set_desc);
    BIND_FN(libskylight, sky_lex_sql);
    BIND_FN(libskylight, sky_trace_span_set_sql);
    BIND_FN(libskylight, sky_trace_span_add_uint_annotation);
    BIND_FN(libskylight, sky_trace_span_done);

    sky_init();

    return 0;
}

skylight_dlopen.h

#ifndef __SKYLIGHT_H__
#define __SKYLIGHT_H__

#include "stddef.h"
#include "stdint.h"

/*
 *
 * ===== Skylight types =====
 *
 */

typedef struct {
    void* data;
    size_t len;
} sky_buf_t;

typedef void sky_instrumenter_t;
typedef void sky_trace_t;


/*
 *
 * ====== Skylight functions =====
 *
 */

int sky_load_libskylight(const char* filename);
typedef int (*sky_main_fn)(int argc, char** argv);
typedef int (*sky_init_fn)();
typedef uint64_t (*sky_hrtime_fn)();
typedef int (*sky_instrumenter_new_fn)(sky_buf_t* env, int envc, sky_instrumenter_t** out);
typedef int (*sky_instrumenter_start_fn)(const sky_instrumenter_t* inst);
typedef int (*sky_instrumenter_stop_fn)(sky_instrumenter_t* inst);
typedef int (*sky_instrumenter_submit_trace_fn)(const sky_instrumenter_t* inst, sky_trace_t* trace);
typedef int (*sky_instrumenter_track_desc_fn)(sky_instrumenter_t* inst, sky_buf_t endpoint, sky_buf_t desc, int* out);
typedef void (*sky_instrumenter_free_fn)(sky_instrumenter_t* val);
typedef int (*sky_trace_new_fn)(uint64_t start, sky_buf_t uuid, sky_buf_t endpoint, sky_trace_t** out);
typedef void (*sky_trace_free_fn)(sky_trace_t* val);
typedef int (*sky_trace_start_fn)(sky_trace_t* trace, uint64_t* out);
typedef int (*sky_trace_endpoint_fn)(sky_trace_t* trace, sky_buf_t* out);
typedef int (*sky_trace_set_endpoint_fn)(const sky_trace_t* trace, sky_buf_t endpoint);
typedef int (*sky_trace_uuid_fn)(sky_trace_t* trace, sky_buf_t* out);
typedef int (*sky_trace_set_uuid_fn)(const sky_trace_t* trace, sky_buf_t uuid);
typedef int (*sky_trace_instrument_fn)(const sky_trace_t* trace, uint64_t time, sky_buf_t category, uint32_t* out);
typedef int (*sky_trace_span_set_title_fn)(const sky_trace_t* trace, uint32_t handle, sky_buf_t title);
typedef int (*sky_trace_span_set_desc_fn)(const sky_trace_t* trace, uint32_t handle, sky_buf_t desc);
typedef int (*sky_lex_sql_fn)(sky_buf_t sql, sky_buf_t* title_buf, sky_buf_t* desc_buf);
typedef int (*sky_trace_span_set_sql_fn)(const sky_trace_t* trace, uint32_t handle, sky_buf_t sql, int flavor);
typedef int (*sky_trace_span_add_uint_annotation_fn)(const sky_trace_t* trace, uint32_t handle, uint32_t key, uint64_t value);
typedef int (*sky_trace_span_done_fn)(const sky_trace_t* trace, uint32_t handle, uint64_t time);

extern sky_main_fn sky_main;
extern sky_init_fn sky_init;
extern sky_hrtime_fn sky_hrtime;
extern sky_instrumenter_new_fn sky_instrumenter_new;
extern sky_instrumenter_start_fn sky_instrumenter_start;
extern sky_instrumenter_stop_fn sky_instrumenter_stop;
extern sky_instrumenter_submit_trace_fn sky_instrumenter_submit_trace;
extern sky_instrumenter_track_desc_fn sky_instrumenter_track_desc;
extern sky_instrumenter_free_fn sky_instrumenter_free;
extern sky_trace_new_fn sky_trace_new;
extern sky_trace_free_fn sky_trace_free;
extern sky_trace_start_fn sky_trace_start;
extern sky_trace_endpoint_fn sky_trace_endpoint;
extern sky_trace_set_endpoint_fn sky_trace_set_endpoint;
extern sky_trace_uuid_fn sky_trace_uuid;
extern sky_trace_set_uuid_fn sky_trace_set_uuid;
extern sky_trace_instrument_fn sky_trace_instrument;
extern sky_trace_span_set_title_fn sky_trace_span_set_title;
extern sky_trace_span_set_desc_fn sky_trace_span_set_desc;
extern sky_lex_sql_fn sky_lex_sql;
extern sky_trace_span_set_sql_fn sky_trace_span_set_sql;
extern sky_trace_span_add_uint_annotation_fn sky_trace_span_add_uint_annotation;
extern sky_trace_span_done_fn sky_trace_span_done;

#endif