local luasql     = nil
local json         = require('cjson')

local ENV         = nil
local CONN         = nil
local CUR         = nil
local result     = {}

local dbname = 'DB_NAME_HERE'
local dbuser = 'DB_USER_NAME_HERE'
local dbpass = 'DB_PASS_HERE'
local dbhost = 'DB_HOST_HERE'
local dbport = 3306

function unrequire(m)
    package.loaded[m] = nil;
    _G[m] = nil;

    -- Search for the shared library handle in the registry and erase it
    local registry = debug.getregistry();
    local nMatches, mKey, mt = 0, nil, registry['_LOADLIB'];

    for key, ud in pairs(registry) do
        if type(key) == 'string' and type(ud) == 'userdata' and getmetatable(ud) == mt and string.find(key, "LOADLIB: .*" .. m) then
            nMatches = nMatches + 1;
            if nMatches > 1 then
                return false, "More than one possible key for module '" .. m .. "'. Can't decide which one to erase.";
            end
            mKey = key;
        end
    end

    if mKey then
        registry[mKey] = nil;
    end

    return true
end

function closeConnection()
    if CONN then CONN:close() end
    if ENV then assert ( ENV:close() ) end
    CONN = nil
    ENV = nil
    CUR = nil
    package.loaded["luasql.mysql"] = nil
    luasql = nil
    unrequire("mysql.so")
end

function setEnvironment()
    if ENV then closeConnection() end
    package.loaded["luasql.mysql"] = nil
    luasql = require "luasql.mysql"
    ENV = assert(luasql.mysql())
end

function createConnection()
    if ENV then
        CONN, err = ENV:connect(dbname, dbuser, dbpass, dbhost, dbport)
        if err then
            result.STATUS     = false
            result.MESSAGE    = err
        end
    end
end

function testConnection()
    if CONN then
        CUR, err = CONN:execute("SELECT VERSION() AS 'VERSION', NOW() AS 'DATE'")
        if err then
            result.STATUS     = false
            result.MESSAGE    = err
        else
            row = CUR:fetch ({}, "a")
            while row do
                result.VERSION     = row.VERSION
                result.DATE     = row.DATE
                result.STATUS     = true
                row = CUR:fetch (row, "a")
            end
        end
        CUR:close()
    end
end

local itCount = arg[1]
for i=1, itCount do
    setEnvironment()
    createConnection()
    testConnection()
    closeConnection()

    print('iter=' .. i)
    print(json.encode(result))

    collectgarbage("collect")
    collectgarbage("collect")
    collectgarbage("collect")
end