From 2253533246b3588c374b6543e1c79891cd6a404d Mon Sep 17 00:00:00 2001
From: Max Cahill <1bardesign@gmail.com>
Date: Sat, 1 Feb 2020 19:30:36 +1100
Subject: [PATCH] [added] manual gc

---
 init.lua      |  2 ++
 manual_gc.lua | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 manual_gc.lua

diff --git a/init.lua b/init.lua
index 23dd107..5da9f6e 100644
--- a/init.lua
+++ b/init.lua
@@ -30,3 +30,5 @@ intersect = require(relative_file("intersect"))
 state_machine = require(relative_file("state_machine"))
 
 async = require(relative_file("async"))
+
+manual_gc = require(relative_file("manual_gc"))
diff --git a/manual_gc.lua b/manual_gc.lua
new file mode 100644
index 0000000..dafbe2d
--- /dev/null
+++ b/manual_gc.lua
@@ -0,0 +1,47 @@
+--[[
+	"semi-manual" garbage collection
+
+	specify a time budget and a memory ceiling per call.
+
+	called once per frame, this will spread any big collections
+	over a couple of frames, and "catch up" when there is. This
+	keeps GC burden much more predictable.
+
+	The memory ceiling provides some level of "relief valve" - if
+	exceeded it will trigger a "full" collection, but this is
+	likely to hurt performance. If you hit the ceiling, it
+	indicates you likely need to either generate less garbage
+	or spent more time each frame collecting.
+
+	1ms (1e-3) is a good place to start for the budget, adjust
+	down or up as needed. games that generate more garbage will
+	need to spend longer on gc each frame.
+
+	64mb is a good place to start for the memory ceiling, though
+	some games will need much more.
+
+	the function steps the garbage collector only do a small step
+	each time. this prevents the start of collection from "spiking",
+	though it still causes some with particularly large sets
+]]
+
+return function(time_budget, safetynet_megabytes, disable_otherwise)
+	local max_steps = 1000
+	local steps = 0
+	local start_time = love.timer.getTime()
+	while
+		love.timer.getTime() - start_time < time_budget and
+		steps < max_steps
+	do
+		collectgarbage("step", 1)
+		steps = steps + 1
+	end
+	--safety net
+	if collectgarbage("count") / 1024 > safetynet_megabytes then
+		collectgarbage("collect")
+	end
+	--don't collect gc outside this margin
+	if disable_otherwise then
+		collectgarbage("stop")
+	end
+end
\ No newline at end of file