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
217
218
219
220
221
222
223
224
225
|
/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2006-2016. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* %CopyrightEnd%
*/
/*
* Purpose: A driver using libpq to connect to Postgres
* from erlang, a sample for the driver documentation
*/
#include <erl_driver.h>
#include <libpq-fe.h>
#include <ei.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "pg_encode.h"
/* Driver interface declarations */
static ErlDrvData start(ErlDrvPort port, char *command);
static void stop(ErlDrvData drv_data);
static int control(ErlDrvData drv_data, unsigned int command, char *buf,
int len, char **rbuf, int rlen);
static void ready_io(ErlDrvData drv_data, ErlDrvEvent event);
static ErlDrvEntry pq_driver_entry = {
NULL, /* init */
start,
stop,
NULL, /* output */
ready_io, /* ready_input */
ready_io, /* ready_output */
"pg_async", /* the name of the driver */
NULL, /* finish */
NULL, /* handle */
control,
NULL, /* timeout */
NULL, /* outputv */
NULL, /* ready_async */
NULL, /* flush */
NULL, /* call */
NULL /* event */
};
typedef struct our_data_t {
PGconn* conn;
ErlDrvPort port;
int socket;
int connecting;
} our_data_t;
/* Keep the following definitions in alignment with the FUNC_LIST
* in erl_pq_sync.erl
*/
#define DRV_CONNECT 'C'
#define DRV_DISCONNECT 'D'
#define DRV_SELECT 'S'
/* #define L fprintf(stderr, "%d\r\n", __LINE__) */
/* INITIALIZATION AFTER LOADING */
/*
* This is the init function called after this driver has been loaded.
* It must *not* be declared static. Must return the address to
* the driver entry.
*/
DRIVER_INIT(pq_drv)
{
return &pq_driver_entry;
}
static char* get_s(const char* buf, int len);
static int do_connect(const char *s, our_data_t* data);
static int do_disconnect(our_data_t* data);
static int do_select(const char* s, our_data_t* data);
/* DRIVER INTERFACE */
static ErlDrvData start(ErlDrvPort port, char *command)
{
our_data_t* data = driver_alloc(sizeof(our_data_t));
data->port = port;
data->conn = NULL;
return (ErlDrvData)data;
}
static void stop(ErlDrvData drv_data)
{
do_disconnect((our_data_t*)drv_data);
}
static int control(ErlDrvData drv_data, unsigned int command, char *buf,
int len, char **rbuf, int rlen)
{
int r;
char* s = get_s(buf, len);
our_data_t* data = (our_data_t*)drv_data;
switch (command) {
case DRV_CONNECT: r = do_connect(s, data); break;
case DRV_DISCONNECT: r = do_disconnect(data); break;
case DRV_SELECT: r = do_select(s, data); break;
default: r = -1; break;
}
driver_free(s);
return r;
}
static int do_connect(const char *s, our_data_t* data)
{
PGconn* conn = PQconnectStart(s);
if (PQstatus(conn) == CONNECTION_BAD) {
ei_x_buff x;
ei_x_new_with_version(&x);
encode_error(&x, conn);
PQfinish(conn);
conn = NULL;
driver_output(data->port, x.buff, x.index);
ei_x_free(&x);
}
PQconnectPoll(conn);
int socket = PQsocket(conn);
data->socket = socket;
driver_select(data->port, (ErlDrvEvent)socket, DO_READ, 1);
driver_select(data->port, (ErlDrvEvent)socket, DO_WRITE, 1);
data->conn = conn;
data->connecting = 1;
return 0;
}
static int do_disconnect(our_data_t* data)
{
ei_x_buff x;
driver_select(data->port, (ErlDrvEvent)data->socket, DO_READ, 0);
driver_select(data->port, (ErlDrvEvent)data->socket, DO_WRITE, 0);
PQfinish(data->conn);
data->conn = NULL;
ei_x_new_with_version(&x);
encode_ok(&x);
driver_output(data->port, x.buff, x.index);
ei_x_free(&x);
return 0;
}
static int do_select(const char* s, our_data_t* data)
{
data->connecting = 0;
PGconn* conn = data->conn;
/* if there's an error return it now */
if (PQsendQuery(conn, s) == 0) {
ei_x_buff x;
ei_x_new_with_version(&x);
encode_error(&x, conn);
driver_output(data->port, x.buff, x.index);
ei_x_free(&x);
}
/* else wait for ready_output to get results */
return 0;
}
static void ready_io(ErlDrvData drv_data, ErlDrvEvent event)
{
PGresult* res = NULL;
our_data_t* data = (our_data_t*)drv_data;
PGconn* conn = data->conn;
ei_x_buff x;
ei_x_new_with_version(&x);
if (data->connecting) {
ConnStatusType status;
PQconnectPoll(conn);
status = PQstatus(conn);
if (status == CONNECTION_OK)
encode_ok(&x);
else if (status == CONNECTION_BAD)
encode_error(&x, conn);
} else {
PQconsumeInput(conn);
if (PQisBusy(conn))
return;
res = PQgetResult(conn);
encode_result(&x, res, conn);
PQclear(res);
for (;;) {
res = PQgetResult(conn);
if (res == NULL)
break;
PQclear(res);
}
}
if (x.index > 1) {
driver_output(data->port, x.buff, x.index);
if (data->connecting)
driver_select(data->port, (ErlDrvEvent)data->socket, DO_WRITE, 0);
}
ei_x_free(&x);
}
/* utilities */
static char* get_s(const char* buf, int len)
{
char* result;
if (len < 1 || len > 1000) return NULL;
result = driver_alloc(len+1);
memcpy(result, buf, len);
result[len] = '\0';
return result;
}
|
