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Lua module for parsing raw redis responses

README.markdown

NAME

lua-redis-parser - Redis reply parser and request constructor library for Lua

Table of Contents

Version

This document describes lua-redis-parser v0.09rc5 released on 28 August 2011.

Description

This lua library implements a thin and fast redis raw response parser that constructs corresponding lua data strucutres, as well as a function that constructs redis raw requests.

To maximize speed, this module is implemented in pure C.

This library is usually used by Lua code running atop lua-nginx-module to access redis backends though redis2-nginx-module.

Functions

The parser variable used below is referring to the variable holding the return value of require "redis.parser". In other words, we assume you have written the following code first:

    local parser = require "redis.parser"

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parse_reply

syntax: res, typ = parser.parse_reply(raw_reply)

Parses the single (or the first) raw redis reply from the raw_reply string and returns the Lua data structure res, as well as the reply type typ.

Here is an example:

    local parser = require 'redis.parser'

    -- assuming the reply variable holds the (single) redis response
    --  to be parsed:
    local res, typ = parser.parse_reply(reply)

    if typ == parser.BAD_REPLY then
        -- res is the textual error message from the parser
    elseif typ == parser.INTEGER_REPLY then
        -- res is an integer, like 3, returned from the redis server
    elseif typ == parser.ERROR_REPLY then
        -- res is the error message from the redis2 server
    elseif typ == parser.STATUS_REPLY then
        -- res is the textual message from the redis server
    elseif typ == parser.BULK_REPLY then
        --- res is a string for the bulk data
    elseif typ == parser.MULTI_BULK_REPLY then
        -- res is a lua (array) table that holds the individual bulks
    end

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parse_replies

syntax: results = parser.parse_replies(raw_replies)

Similar to the parse_reply method, but parse multiple pipelined redis replies in the raw_replies string argument. Returns a table of all the parsed results where each result is an array-like table consists of two elements, res and typ, which have exactly the same meaning as the return values of the parse_reply function.

For instance,

    local parser = require "redis.parser"

    -- assuming the replies variable holds n redis responses
    --  to be parsed:
    local results = parser.parse_replies(replies, n)
    for i, result in ipairs(results) do
        local res = result[1]
        local typ = result[2]

        -- res and typ have exactly the same meaning as in
        --  the parse_reply method documented above
    end

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typename

syntax: str = parser.typename(typ)

Returns the textual representation of the reply type values returned by the parse_reply and parse_replies functions. Here's the correspondence:

    parser.typename(parser.BAD_REPLY)        == "bad reply"
    parser.typename(parser.INTEGER_REPLY)    == "integer reply"
    parser.typename(parser.ERROR_REPLY)      == "error reply"
    parser.typename(parser.STATUS_REPLY)     == "status reply"
    parser.typename(parser.BULK_REPLY)       == "bulk reply"
    parser.typename(parser.MULTI_BULK_REPLY) == "multi-bulk reply"

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build_query

syntax: raw_request = parser.build_query(args)

Constructs a raw Redis request from simple Lua values. It simply accepts a Lua array-like table, a list of parameters including the command name.

Please check out the complete list of redis 2.0 commands,

http://redis.io/commands

The first command in that list, "APPEND key value", for example, we can just use

    local parser = require "redis.parser"

    local req = parser.build_query({'APPEND', 'some-key', 'some-value'})

to construct a binary request in the return value. Because the Redis command is case insensitive, I usually just use 'append', the lower case form, as the first element of that list, as in

    local parser = require "redis.parser"

    local req = parser.build_query({'set', 'foo', 'some value'})
        -- req is the raw TCP request ready to send to the remote redis server
        -- over the TCP connection

Null values should be specified by parser.null rather than Lua's nil value.

Boolean values will be converted to 1 or 0, for true and false, respectively.

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Constants

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BAD_REPLY

syntax: typ = parser.BAD_REPLY

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INTEGER_REPLY

syntax: typ = parser.INTEGER_REPLY

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ERROR_REPLY

syntax: typ = parser.ERROR_REPLY

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STATUS_REPLY

syntax: typ = parser.STATUS_REPLY

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BULK_REPLY

syntax: typ = parser.BULK_REPLY

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MULTI_BULK_REPLY

syntax: typ = parser.MULTI_BULK_REPLY

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null

syntax: val = parser.null

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Background

This module is originally written for lua-nginx-module and redis2-nginx-module:

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Report Bugs

Although a lot of effort has been put into testing and code tuning, there must be some serious bugs lurking somewhere in this module. So whenever you are bitten by any quirks, please don't hesitate to

  1. create a ticket on the issue tracking interface provided by GitHub,
  2. or send a bug report or even patches to agentzh@gmail.com.

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Source Repository

Available on GitHub at agentzh/lua-redis-parser.

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Installation

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Build requirements

Gnu make and gcc is required to build this module.

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Linux/BSD/Solaris

    gmake CC=gcc
    gmake install CC=gcc

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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.

This library is included and enabled by default in the ngx_openresty bundle.

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Author

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Copyright & License

This module is licenced under the BSD license.

Copyright (C) 2009, 2010, 2011, Taobao Inc., Alibaba Group ( http://www.taobao.com ).

Copyright (C) 2009, 2010, 2011, by 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.

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SEE ALSO

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