udf_reg_real_func.cc

/* Copyright (c) 2017, 2024, Oracle and/or its affiliates.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.

This program is designed to work with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation.  The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have either included with
the program or referenced in the documentation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License, version 2.0, for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/* This test component register the UDF myfunc_double in init (install) and
   don't unregister it. The unregister can be done by calling the test component
   udf_unreg_int_func.cc, doing it in init (install). */

#include <ctype.h>
#include <mysql/components/component_implementation.h>
#include <mysql/components/service_implementation.h>
#include <mysql/components/services/udf_registration.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <string>

REQUIRES_SERVICE_PLACEHOLDER(udf_registration);
REQUIRES_SERVICE_PLACEHOLDER(udf_registration_aggregate);

/***************************************************************************
** UDF double function.
** Arguments:
** initid       Structure filled by xxx_init
** args         The same structure as to xxx_init. This structure
**              contains values for all parameters.
**              Note that the functions MUST check and convert all
**              to the type it wants!  Null values are represented by
**              a NULL pointer
** is_null      If the result is null, one should store 1 here.
** error        If something goes fatally wrong one should store 1 here.
**
** This function should return the result.
***************************************************************************/

bool myfunc_double_init(UDF_INIT *initid, UDF_ARGS *args, char *message) {
  unsigned i;

  if (!args->arg_count) {
    strcpy(message, "myfunc_double must have at least one argument");
    return true;
  }
  /*
  ** As this function wants to have everything as strings, force all arguments
  ** to strings.
  */
  for (i = 0; i < args->arg_count; i++) args->arg_type[i] = STRING_RESULT;
  initid->maybe_null = true; /* The result may be null */
  initid->decimals = 2;      /* We want 2 decimals in the result */
  initid->max_length = 6;    /* 3 digits + . + 2 decimals */
  return false;
}

double myfunc_double(UDF_INIT *, UDF_ARGS *args, unsigned char *is_null,
                     unsigned char *) {
  unsigned long val = 0;
  unsigned long v = 0;
  unsigned i, j;

  for (i = 0; i < args->arg_count; i++) {
    if (args->args[i] == nullptr) continue;
    val += args->lengths[i];
    for (j = args->lengths[i]; j-- > 0;) v += args->args[i][j];
  }
  if (val) return (double)v / (double)val;
  *is_null = 1;
  return 0.0;
}

/**************************************************************************************/

static mysql_service_status_t init() {
  bool ret_double = false;
  ret_double = mysql_service_udf_registration->udf_register(
      "myfunc_double", REAL_RESULT, (Udf_func_any)myfunc_double,
      myfunc_double_init, nullptr);
  return ret_double;
}

static mysql_service_status_t deinit() {
  int was_present = 0;
  for (int i = 0; i < 10; i++) {
    mysql_service_udf_registration->udf_unregister("myfunc_double",
                                                   &was_present);
    if (was_present != 0) break;
  }
  return false;
}

BEGIN_COMPONENT_PROVIDES(test_udf_registration)
END_COMPONENT_PROVIDES();

BEGIN_COMPONENT_REQUIRES(test_udf_registration)
REQUIRES_SERVICE(udf_registration),
    REQUIRES_SERVICE(udf_registration_aggregate), END_COMPONENT_REQUIRES();

BEGIN_COMPONENT_METADATA(test_udf_registration)
METADATA("mysql.author", "Oracle Corporation"),
    METADATA("mysql.license", "GPL"), METADATA("test_property", "1"),
    END_COMPONENT_METADATA();

DECLARE_COMPONENT(test_udf_registration, "mysql:test_udf_registration")
init, deinit END_DECLARE_COMPONENT();

DECLARE_LIBRARY_COMPONENTS &COMPONENT_REF(test_udf_registration)
    END_DECLARE_LIBRARY_COMPONENTS