# lua-rds-parser **Repository Path**: mirrors_openresty/lua-rds-parser ## Basic Information - **Project Name**: lua-rds-parser - **Description**: Resty DBD Stream (RDS) parser for Lua written in C - **Primary Language**: Unknown - **License**: Not specified - **Default Branch**: master - **Homepage**: None - **GVP Project**: No ## Statistics - **Stars**: 0 - **Forks**: 0 - **Created**: 2020-08-18 - **Last Updated**: 2026-01-10 ## Categories & Tags **Categories**: Uncategorized **Tags**: None ## README 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 , CloudFlare Inc. Copyright & License =================== This module is licenced under the BSD license. Copyright (C) 2011-2016, Zhang "agentzh" Yichun (章亦春) . 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.