mirrors_openresty/lua-rds-parser

Name
====

lua-rds-parser - Resty-DBD-Stream (RDS) parser for Lua written in C

Status
======

This module is production ready.

Synopsis
========

```lua
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](https://github.com/openresty/drizzle-nginx-module#readme)
and [ngx_postgres](https://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` (or `ngx.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,

```lua
parser.null == cjson.null ~= yajl.null
```

Using with HttpDrizzleModule
============================

To use with `ngx_drizzle`, here is a small example:

```nginx
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
----------------

```bash
gmake CC=gcc
gmake install CC=gcc
```

Mac OS X
--------

```bash
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:

```bash
make LUA_INCLUDE_DIR=/opt/luajit/include/luajit-2.0
```

You can specify a custom path for the installation target:

```bash
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
======

Yichun "agentzh" Zhang <agentzh@gmail.com>, CloudFlare Inc.

Copyright & License
===================

This module is licenced under the BSD license.

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.

mirrors_openresty/lua-rds-parser

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