summaryrefslogtreecommitdiff
path: root/client/async_example.c
blob: ccb60950904950b118f3be73e3fe33e59d004693 (plain)
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
208
209
210
211
212
213
214
215
216
/*
  Copyright 2011 Kristian Nielsen and Monty Program Ab.

  This file is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser 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_OPT_NONBLOCK, 0);
  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);

  /*
    mysql_close() sends a COM_QUIT packet, and so in principle could block
    waiting for the socket to accept the data.
    In practise, for many applications it will probably be fine to use the
    blocking mysql_close().
   */
  status= mysql_close_start(&mysql);
  while (status)
  {
    status= wait_for_mysql(&mysql, status);
    status= mysql_close_cont(&mysql, status);
  }
}

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;
}