do

local ffi = require('ffi');

ffi.cdef[[
unsigned long shift(char *s);
unsigned long bitwise(char *s);
]]
local ibit = ffi.load('ibit');

local function str2point(str)
    md5 = ngx.md5(str);
    --point = tonumber(ffi.string(xbit.bitwise(ffi.cast("char *", tostring(md5)))));
    point = tonumber(ibit.bitwise(ffi.cast("char *", tostring(md5))));
    return point;
end


-- sps = aring
-- sp = point
local function search(sp, sps, pstart, pend, n)
    n = n + 1;
    local mid, mod = math.modf((pstart + pend) / 2);
    if n > 20 then
        ngx.log(ngx.ERR, 'the point ' .. sp .. ' cycle index exceed 20');
        ngx.exit(509);
    end
    if sps[mid] >= sp and sps[mid - 1] < sp then
        return sps[mid];
    elseif sps[mid + 1] >= sp and sps[mid] < sp then
        return sps[mid + 1];
    elseif sps[mid] > sp then
        pend = mid;
        return search(sp, sps, pstart, pend, n);
    elseif sps[mid] < sp then
        pstart = mid;
        return search(sp, sps, pstart, pend, n);
    end
end

-- fps = points
-- frs = rings
-- fnode = node name
local function findhost(fp, fps, ffls, fsgls, fls, frs, fnode)
    local fflag = ffls.get(fnode);
    if fflag == 's' then
        --ngx.say('single <br>');
        return fsgls.get(fnode);
    elseif fflag == 'h' then
        local ps = fps.get(fnode);
        local fend = table.getn(ps);

        if fp <= ps[1] or ps[fend] < fp then
            return frs.get(fnode).get(ps[1]);
        else
            tp = search(fp, ps, 1, fend, 0);
            if tp ~= nil then
                return frs.get(fnode).get(tp);
            else
                ngx.log(ngx.ERR, 'search ring error ' .. fp .. '<br>');
            end
        end
    elseif fflag == 'l' then
        floops = fls.get(fnode);
        total = table.getn(floops);
        math.randomseed(os.time());
        rp = math.random(1, total);
        return floops[rp];
    end
end

ring = {
    bitwise = bitwise,
    str2point = str2point,
    findhost = findhost,
}

end