async_example.c 4.67 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207
/*
  Copyright 2011 Kristian Nielsen and Monty Program Ab.

  Experiments with non-blocking libmysql.

  This is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 2 of the License, or
  (at your option) any later version.

  This 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 for more details.

  You should have received a copy of the GNU General Public License
  along with this.  If not, see <http://www.gnu.org/licenses/>.
*/


#ifndef __WIN__
#include <poll.h>
#else
#include <WinSock2.h>
#endif

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

#define SL(s) (s), sizeof(s)

static const char *my_groups[]= { "client", NULL };

static int
wait_for_mysql(MYSQL *mysql, int status)
{
#ifdef __WIN__
  fd_set rs, ws, es;
  int res;
  struct timeval tv, *timeout;
  my_socket s= mysql_get_socket(mysql);
  FD_ZERO(&rs);
  FD_ZERO(&ws);
  FD_ZERO(&es);
  if (status & MYSQL_WAIT_READ)
    FD_SET(s, &rs);
  if (status & MYSQL_WAIT_WRITE)
    FD_SET(s, &ws);
  if (status & MYSQL_WAIT_EXCEPT)
    FD_SET(s, &es);
  if (status & MYSQL_WAIT_TIMEOUT)
  {
    tv.tv_sec= mysql_get_timeout_value(mysql);
    tv.tv_usec= 0;
    timeout= &tv;
  }
  else
    timeout= NULL;
  res= select(1, &rs, &ws, &es, timeout);
  if (res == 0)
    return MYSQL_WAIT_TIMEOUT;
  else if (res == SOCKET_ERROR)
  {
    /*
      In a real event framework, we should handle errors and re-try the select.
    */
    return MYSQL_WAIT_TIMEOUT;
  }
  else
  {
    int status= 0;
    if (FD_ISSET(s, &rs))
      status|= MYSQL_WAIT_READ;
    if (FD_ISSET(s, &ws))
      status|= MYSQL_WAIT_WRITE;
    if (FD_ISSET(s, &es))
      status|= MYSQL_WAIT_EXCEPT;
    return status;
  }
#else
  struct pollfd pfd;
  int timeout;
  int res;

  pfd.fd= mysql_get_socket(mysql);
  pfd.events=
    (status & MYSQL_WAIT_READ ? POLLIN : 0) |
    (status & MYSQL_WAIT_WRITE ? POLLOUT : 0) |
    (status & MYSQL_WAIT_EXCEPT ? POLLPRI : 0);
  if (status & MYSQL_WAIT_TIMEOUT)
    timeout= 1000*mysql_get_timeout_value(mysql);
  else
    timeout= -1;
  res= poll(&pfd, 1, timeout);
  if (res == 0)
    return MYSQL_WAIT_TIMEOUT;
  else if (res < 0)
  {
    /*
      In a real event framework, we should handle EINTR and re-try the poll.
    */
    return MYSQL_WAIT_TIMEOUT;
  }
  else
  {
    int status= 0;
    if (pfd.revents & POLLIN)
      status|= MYSQL_WAIT_READ;
    if (pfd.revents & POLLOUT)
      status|= MYSQL_WAIT_WRITE;
    if (pfd.revents & POLLPRI)
      status|= MYSQL_WAIT_EXCEPT;
    return status;
  }
#endif
}

static void
fatal(MYSQL *mysql, const char *msg)
{
  fprintf(stderr, "%s: %s\n", msg, mysql_error(mysql));
  exit(1);
}

static void
doit(const char *host, const char *user, const char *password)
{
  int err;
  MYSQL mysql, *ret;
  MYSQL_RES *res;
  MYSQL_ROW row;
  int status;

  mysql_init(&mysql);
  mysql_options(&mysql, MYSQL_READ_DEFAULT_GROUP, "myapp");

  /* Returns 0 when done, else flag for what to wait for when need to block. */
  status= mysql_real_connect_start(&ret, &mysql, host, user, password, NULL,
                                   0, NULL, 0);
  while (status)
  {
    status= wait_for_mysql(&mysql, status);
    status= mysql_real_connect_cont(&ret, &mysql, status);
  }

  if (!ret)
    fatal(&mysql, "Failed to mysql_real_connect()");

  status= mysql_real_query_start(&err, &mysql, SL("SHOW STATUS"));
  while (status)
  {
    status= wait_for_mysql(&mysql, status);
    status= mysql_real_query_cont(&err, &mysql, status);
  }
  if (err)
    fatal(&mysql, "mysql_real_query() returns error");

  /* This method cannot block. */
  res= mysql_use_result(&mysql);
  if (!res)
    fatal(&mysql, "mysql_use_result() returns error");

  for (;;)
  {
    status= mysql_fetch_row_start(&row, res);
    while (status)
    {
      status= wait_for_mysql(&mysql, status);
      status= mysql_fetch_row_cont(&row, res, status);
    }
    if (!row)
      break;
    printf("%s: %s\n", row[0], row[1]);
  }
  if (mysql_errno(&mysql))
    fatal(&mysql, "Got error while retrieving rows");
  mysql_free_result(res);

  /* I suppose this must be non-blocking too. */
  mysql_close(&mysql);
}

int
main(int argc, char *argv[])
{
  int err;

  if (argc != 4)
  {
    fprintf(stderr, "Usage: %s <host> <user> <password>\n", argv[0]);
    exit(1);
  }

  err= mysql_library_init(argc, argv, (char **)my_groups);
  if (err)
  {
    fprintf(stderr, "Fatal: mysql_library_init() returns error: %d\n", err);
    exit(1);
  }

  doit(argv[1], argv[2], argv[3]);

  mysql_library_end();

  return 0;
}