Fix several bugs, test behavior and profile (insert 8-32 microseconds, delete 22-37 microseconds)

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teknomunk 2024-04-08 08:10:20 +00:00
parent 28113cfda7
commit 6ca7c277b5
1 changed files with 204 additions and 0 deletions

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--[[
== Radix/Finger queue class
This is a queue based off the concepts behind finger trees (https://en.wikipedia.org/wiki/Finger_tree),
the radix sort (https://en.wikipedia.org/wiki/Radix_sort) and funnel sort (https://en.wikipedia.org/wiki/Funnelsort)
This algorithm has O(1) deletion and O(k) insertion (k porportional to the time in the future) and uses log_4(n) tree nodes.
At the top level of the queue, there is a 20-element array of linked lists containing tasks that are scheduled to
start running in the current second. Removing the next linked list of tasks from this array is an O(1) operation.
The queue then has a one-sided finger tree of 20-element lists that are used to replace the initial queue when the
second rolls over.
]]
function Class()
local cls = {}
cls.mt = { __index = cls }
function cls:new(...)
local inst = setmetatable({}, cls.mt)
local construct = inst.construct
if construct then inst:construct(...) end
return inst
end
return cls
end
local inner_queue = Class()
function inner_queue:construct(level)
self.level = level
self.items = {}
self.unsorted_count = 0
self.slots = 4
-- Precompute slot size
local slot_size = 20
for i = 2,level do
slot_size = slot_size * 4
end
self.slot_size = slot_size
end
function inner_queue:get()
local slots = self.slots
local slot = 5 - slots
local ret = self.items[slot]
self.items[slot] = nil
-- Take a way a slot, then refill if needed
slots = slots - 1
if slots == 0 then
if self.next_level then
local next_level_get = self.next_level:get()
if next_level_get then
self.items = next_level_get.items
else
self.items = {}
end
slots = 4
end
end
self.slots = slots
return ret or self:init_slot_list()
end
function inner_queue:add_tasks(tasks, time)
local task = tasks
local slot_size = self.slot_size
local level = self.level
local slots = self.slots
while task do
local t = task.time
t = t - time
if t > slot_size * slots then
-- Add to list for next level in the finger tree
task.time = t
local curr_task = task
task = task.next
curr_task.next = self.first_unsorted
local count = self.unsorted_count + 1
if count > 20 then
if not self.next_level then
self.next_level = inner_queue:new(self.level + 1)
end
self.next_level:add_tasks(curr_task, slot_size * slots)
self.first_unsorted = nil
self.unsorted_count = 0
else
self.first_unsorted = curr_task
self.unsorted_count = count
end
else
-- Task belongs in a slot on this level
local slot = math.floor(t / slot_size) + 1 + ( slots - 4 )
t = t % slot_size
task.time = t
local curr_task = task
task = task.next
local list = self.items[slot] or self:init_slot_list()
self.items[slot] = list
if level == 1 then
curr_task.next = list[t]
list[t] = curr_task
else
list:add_tasks(curr_task, (slot - 1) * slot_size)
end
end
end
end
function inner_queue:init_slot_list()
local level = self.level
if level == 1 then
return { {}, {}, {}, {} }
else
local r = {}
for i=1,4 do
r[i] = inner_queue:new(self.level - 1)
end
end
end
local queue = Class()
function queue:construct()
self.items = {}
self.unsorted_count = 0
self.m_tick = 1
self.next_level = inner_queue:new(1)
end
function queue:add_task(task)
-- Adjust time to align with the start of the current second
task.time = task.time + self.m_tick
-- Handle task in current seccond
if task.time <= 20 then
task.next = self.items[task.time]
self.items[task.time] = task
return
end
local count = self.unsorted_count + 1
if count > 20 then
-- Push to next level
self.unsorted_count = 0
else
-- Add to the list of tasks for later time slots
task.next = self.first_unsorted
self.first_unsorted = task
self.unsorted_count = count
end
end
function queue:tick()
-- Get the tasks for this tick
local ret = self.items[self.m_tick]
self.items[self.m_tick] = nil
self.m_tick = self.m_tick + 1
-- Handle second rollover
if self.m_tick == 21 then
-- Push items to next level
if self.first_unsorted then
self.next_level:add_tasks(self.first_unsorted, 20)
self.first_unsorted = nil
self.unsorted_count = 0
end
self.items = self.next_level:get()
self.m_tick = 1
end
return ret or {}
end
local t = queue.new()
local test_times = { 15, 1, 7, 34, 50, 150, 14, 18, 20, 20, 15, }
local start_time = minetest.get_us_time()
for _,time in pairs(test_times) do
t:add_task({ time = time })
local stop_time = minetest.get_us_time()
print("took "..tostring(stop_time - start_time).."us")
start_time = stop_time
end
print(dump(t:tick()))
print(dump(t))
local start_time = minetest.get_us_time()
for i=1,60 do
local s = t:tick()
print("time="..tostring(i+1))
print(dump(s))
local stop_time = minetest.get_us_time()
print("took "..tostring(stop_time - start_time).."us")
start_time = stop_time
end