benchmark the new LRU cache implementation

worldeditadditions/utils/lru_benchmark.lua

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+local LRU = require("lru")
+local operations = 100000
+local values = {
+	"Abiu", "Açaí", "Acerola", "Ackee", "African cucumber", "Apple", "Apricot",
+	"Avocado", "Banana", "Bilberry", "Blackberry", "Blackcurrant",
+	"Black sapote", "Blueberry", "Boysenberry", "Breadfruit", "Cactus pear",
+	"Canistel", "Cempedak", "Cherimoya", "Cherry", "Chico fruit", "Cloudberry",
+	"Coco De Mer", "Coconut", "Crab apple", "Cranberry", "Currant", "Damson",
+	"Date", "Dragonfruit (or Pitaya)", "Durian", "Egg Fruit", "Elderberry",
+	"Feijoa", "Fig", "Finger Lime", "Goji berry", "Gooseberry", "Grape",
+	"Raisin", "Grapefruit", "Grewia asiatica", "Guava", "Hala Fruit",
+	"Honeyberry", "Huckleberry", "Jabuticaba", "Jackfruit", "Jambul",
+	"Japanese plum", "Jostaberry", "Jujube", "Juniper berry", "Kaffir Lime",
+	"Kiwano", "Kiwifruit", "Kumquat", "Lemon", "Lime", "Loganberry", "Longan",
+	"Loquat"
+}
+
+-- From http://lua-users.org/wiki/SimpleRound
+function round(num, numDecimalPlaces)
+	local mult = 10^(numDecimalPlaces or 0)
+	return math.floor(num * mult + 0.5) / mult
+end
+
+--- Pads str to length len with char from right
+-- @source https://snipplr.com/view/13092/strlpad--pad-string-to-the-left
+local function str_padend(str, len, char)
+	if char == nil then char = ' ' end
+	return str .. string.rep(char, len - #str)
+end
+--- Pads str to length len with char from left
+-- Adapted from the above
+local function str_padstart(str, len, char)
+	if char == nil then char = ' ' end
+	return string.rep(char, len - #str) .. str
+end
+
+
+local values_count = #values
+
+function test(size)
+	local cpu_start = os.clock()
+	
+	
+	local lru = LRU.new(size)
+	
+	local hits = 0
+	local misses = 0
+	for i=1,operations do
+		local key = values[math.random(1, values_count)]
+		if math.random() >= 0.5 then
+			-- set
+			lru:set(key, math.random())
+		else
+			-- get
+			if lru:get(key) == nil then
+				misses = misses + 1
+				lru:set(key, math.random())
+			else
+				hits = hits + 1
+			end
+		end
+	end
+	
+	
+	local cpu_end = os.clock()
+	print(
+		size,
+		str_padend(tostring(round(cpu_end - cpu_start, 6)), 9),
+		hits, misses,
+		((hits/operations)*100)
+	)
+end
+
+
+io.stderr:write("OPERATIONS\t"..operations.."\n")
+print("size", "cpu time", "hits", "misses", "hit ratio (%)")
+for i=3,256 do
+	io.stderr:write("size "..i.."\r")
+	test(i)
+	
+end