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
|
Name
lua-rds-parser - Resty-DBD-Stream (RDS) parser for Lua written in C
Status
This module is production ready.
Synopsis
local parser = require "rds.parser"
local res, err = parser.parse(rds)
if res == nil then
error("failed to parse: " .. err)
end
print(res.errcode)
print(res.errstr)
print(res.insert_id)
print(res.affected_rows)
local rows = res.resultset
if rows then
for i, row in ipairs(rows) do
for col, val in pairs(row) do
if val ~= parser.null then
print(col .. ": " .. val)
end
end
end
end
Description
This Lua library can be used to parse the Resty-DBD-Stream formatted data
generated by ngx_drizzle (http://wiki.nginx.org/HttpDrizzleModule )
and ngx_postgres (http://github.com/FRiCKLE/ngx_postgres/ ) into Lua
data structures. In the past, we have to use JSON as the intermediate data
format which is quite inefficient in terms of both memory and CPU time.
To maximize speed and minimize memory footprint, this library is implemented
in pure C.
Null values in RDS are turned into the light user data "parser.null"
where "parser" is the module object returned by Lua's "require".
JSON Serialization
If you want to serialize the parsed result into JSON, please
use the lua-cjson library (http://www.kyne.com.au/~mark/software/lua-cjson.php )
instead of lua-yajl, because lua-cjson is faster than lua-yajl
in many common cases, and more importantly,
parser.null == cjson.null ~= yajl.null
Using with HttpDrizzleModule
To use with ngx_drizzle, here is a small example:
upstream backend {
drizzle_server 127.0.0.1:3306 protocol=mysql
dbname=ngx_test user=ngx_test password=ngx_test;
drizzle_keepalive max=10 overflow=ignore mode=single;
}
server {
...
location /mysql {
drizzle_query $echo_request_body;
drizzle_pass backend;
}
location /api {
content_by_lua '
local sql = "select * from cats"
local resp = ngx.location.capture("/mysql", {
method = ngx.HTTP_POST, body = sql
})
if resp.status ~= ngx.HTTP_OK or not resp.body then
error("failed to query mysql")
end
local parser = require "rds.parser"
local res, err = parser.parse(resp.body)
if res == nil then
error("failed to parse RDS: " .. err)
end
local rows = res.resultset
if not rows or #rows == 0 then
ngx.say("empty resultset")
ngx.exit(0)
end
for i, row in ipairs(rows) do
ngx.print("row ", i, ": ")
for col, val in pairs(row) do
if val ~= parser.null then
ngx.print(col, "=", val, " ")
else
ngx.print(col, "=null ")
end
end
ngx.say()
end
';
}
}
On my machine, GET /api will yield
row 1: id=2 name=null
row 2: id=3 name=bob
of course, the actual output depends on the structure and contents of the
"cats" table in the mysql database.
You can use this Lua library with the ngx_postgres module in a similar way.
Installation
Build requirements
* Lua (http://www.lua.org/)
* or LuaJIT (http://www.luajit.org/)
Gnu make and gcc is required to build this module.
Linux/BSD/Solaris
gmake CC=gcc
gmake install CC=gcc
Mac OS X
make LDFLAGS='-bundle -undefined dynamic_lookup' CC=gcc
make install
If your Lua or LuaJIT is not installed into the system, specify its
include directory like this:
make LUA_INCLUDE_DIR=/opt/luajit/include/luajit-2.0
You can specify a custom path for the installation target:
make install LUA_LIB_DIR=/opt/lualib
The "DESTDIR" variable is also supported, to ease RPM packaging.
TODO
* add support for option "compact" to generate a compact
Lua table for the "resultset" field.
Known Issues
* The endianness flag in RDS is not supported yet in this library,
and it will assume it's of the host's endian. So do not
try parsing the RDS stream that is generated by another
machine of a different endian.
Author
Zhang "agentzh" Yichun <agentzh@gmail.com>
Copyright & License
This module is licenced under the BSD license.
Copyright (C) 2011, Zhang "agentzh" Yichun (章亦春) <agentzh@gmail.com>.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
