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distributor: improve fairness by using random spread

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Distributor iterates through filter indices always in the same order,
accidentally favouring certain ports. This is particularly noticeable
for 3 outputs configured with the same item - lowest numbered port
is receiving double quantity (TA2 distributor moves items in pack of 4).

Fix provided in this patch adds an extra mapping for filter indexing,
permutating randomly outputs with identical items so no ports are
preferred anymore.

Signed-off-by: Michal Cieslakiewicz <michal.cieslakiewicz@wp.pl>
This commit is contained in:
Michal Cieslakiewicz 2020-08-07 21:59:15 +02:00
parent 240c6e20ab
commit fbe4c914d7
1 changed files with 15 additions and 1 deletions
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16
basic_machines/distributor.lua
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@ -35,6 +35,19 @@ local SlotColors = {"red", "green", "blue", "yellow"}
local Num2Ascii = {"B", "L", "F", "R"} local Num2Ascii = {"B", "L", "F", "R"}
local FilterCache = {} -- local cache for filter settings local FilterCache = {} -- local cache for filter settings
-- Permutation table to improve distribution between ports (number of ports: 1-4)
-- Usage: permIdx[num_ports][math.random(1, #permIdx[num_ports])][idx]
local permIdx = {
{ { 1 } },
{ { 1, 2 }, { 2, 1 } },
{ { 1, 2, 3 }, { 1, 3, 2 }, { 2, 1, 3 }, { 2, 3, 1 }, { 3, 1, 2 }, { 3, 2, 1 } },
{ { 1, 2, 3, 4 }, { 1, 2, 4, 3 }, { 1, 3, 2, 4 }, { 1, 3, 4, 2 }, { 1, 4, 2, 3 },
{ 1, 4, 3, 2 }, { 2, 1, 3, 4 }, { 2, 1, 4, 3 }, { 2, 3, 1, 4 }, { 2, 3, 4, 1 },
{ 2, 4, 1, 3 }, { 2, 4, 3, 1 }, { 3, 1, 2, 4 }, { 3, 1, 4, 2 }, { 3, 2, 1, 4 },
{ 3, 2, 4, 1 }, { 3, 4, 1, 2 }, { 3, 4, 2, 1 }, { 4, 1, 2, 3 }, { 4, 1, 3, 2 },
{ 4, 2, 1, 3 }, { 4, 2, 3, 1 }, { 4, 3, 1, 2 }, { 4, 3, 2, 1 }, }
}
local function filter_settings(pos) local function filter_settings(pos)
local meta = M(pos) local meta = M(pos)
local param2 = techage.get_node_lvm(pos).param2 local param2 = techage.get_node_lvm(pos).param2
@ -206,11 +219,12 @@ local function push_item(pos, filter, item_name, num_items, nvm)
local idx = 1 local idx = 1
local num_pushed = 0 local num_pushed = 0
local num_ports = #filter local num_ports = #filter
local randidx = permIdx[num_ports][math.random(1, #permIdx[num_ports])]
local amount = math.floor(math.max((num_items + 1) / num_ports, 1)) local amount = math.floor(math.max((num_items + 1) / num_ports, 1))
local num_of_trials = 0 local num_of_trials = 0
while num_pushed < num_items and num_of_trials <= 8 do while num_pushed < num_items and num_of_trials <= 8 do
num_of_trials = num_of_trials + 1 num_of_trials = num_of_trials + 1
local push_dir = filter[idx] local push_dir = filter[randidx[idx]]
local num_to_push = math.min(amount, num_items - num_pushed) local num_to_push = math.min(amount, num_items - num_pushed)
if techage.push_items(pos, push_dir, ItemStack(item_name.." "..num_to_push)) then if techage.push_items(pos, push_dir, ItemStack(item_name.." "..num_to_push)) then
num_pushed = num_pushed + num_to_push num_pushed = num_pushed + num_to_push