myrocks proc init梳理

void native_procedure_init() {  TABLE_LIST tables;  MEM_ROOT mem;  READ_RECORD read_record_info;  TABLE *table;  int error;  DBUG_ENTER("native_procedure_init");#ifdef HAVE_PSI_INTERFACE  init_psi_keys();#endif  mysql_rwlock_init(key_THR_LOCK_np, &THR_LOCK_np);  init_sql_alloc(&mem, UDF_ALLOC_BLOCK_SIZE, 0);  // Initialize THD (we don't have THD during server startup).  THD *new_thd = new THD;  if (!new_thd) {    // NO_LINT_DEBUG    sql_print_error("Can't allocate memory for native procedures");    free_root(&mem, MYF(0));    DBUG_VOID_RETURN;  }  new_thd->thread_stack = (char *)&new_thd;  new_thd->store_globals();  new_thd->set_db(system_db, sizeof(system_db) - 1);  // Open mysql.native_proc table.  tables.init_one_table(system_db, sizeof(system_db), system_table,                        sizeof(system_table), system_table, TL_READ);  if (open_and_lock_tables(new_thd, &tables, FALSE,                           MYSQL_LOCK_IGNORE_TIMEOUT)) {    // NO_LINT_DEBUG    sql_print_error("Can't open the mysql.native_proc table. "                    "Please run mysql_upgrade to create it.");    goto exit;  }  // Read records in table.  table = tables.table;  if (init_read_record(&read_record_info, new_thd, table, NULL, 1, 1, FALSE))    goto exit;  table->use_all_columns();  while (!(error = read_record_info.read_record(&read_record_info))) {    native_proc np;    np.name = get_field(&mem, table->field[0]);    np.dl = get_field(&mem, table->field[2]);    DBUG_ASSERT(strcmp("native", get_field(&mem, table->field[1])) == 0);    if (add_native_procedure(&np)) {      // NO_LINT_DEBUG      sql_print_error("Error adding native procedure: '%.64s'",                      np.name.c_str());    } else {      DBUG_ASSERT(proc_map.count(np.name) > 0);      proc_map[np.name].enabled = true;    }  }  if (error > 0) {    // NO_LINT_DEBUG    sql_print_error("Got unknown error: %d", my_errno);  }  end_read_record(&read_record_info);  // Force close to free memory.  table->m_needs_reopen = TRUE;exit:  close_mysql_tables(new_thd);  free_root(&mem, MYF(0));  delete new_thd;  my_pthread_setspecific_ptr(THR_THD, 0);  DBUG_VOID_RETURN;}

看源码 它是先从 system_table 中找相关符号 然后读取，之后做 add_native_procedure

static int add_native_procedure(native_proc *np) {  void *dl = nullptr;  bool dlclose_needed = false;  if (proc_map.count(np->name) > 0) {    my_error(ER_NP_PROCEDURE_EXISTS, MYF(0), np->name.c_str());    return 1;  }  dl = search_dlhandle(np->dl);  // If dlhandle not present, dlopen the shared object.  if (dl == nullptr) {    char dlpath[FN_REFLEN];    strxnmov(dlpath, sizeof(dlpath) - 1, opt_plugin_dir, "/", np->dl.c_str(),             NullS);    unpack_filename(dlpath, dlpath);    if (!(dl = dlopen(dlpath, RTLD_NOW))) {      const char *errmsg;      int error_number = dlopen_errno;      DLERROR_GENERATE(errmsg, error_number);      my_error(ER_CANT_OPEN_LIBRARY, MYF(0), np->dl.c_str(), error_number,               errmsg);      return 1;    }    dlclose_needed = true;  }  np->dlhandle = dl;  // Lookup function pointer with dlsym.  if (!(np->proc = (proc_t *)dlsym(np->dlhandle, np->name.c_str()))) {    my_error(ER_CANT_FIND_DL_ENTRY, MYF(0), np->name.c_str());    if (dlclose_needed) {      DBUG_ASSERT(dl);      dlclose(dl);    }    return 1;  }  // Insert into proc_map.  proc_map[np->name] = *np;  return 0;}

这里做了将 名字 和 函数做了关联 分别用了 dlopen（打开句柄）,dlsym符号链接