From 8ab47b2c7814b002facc05bc1f12405b76598f8a Mon Sep 17 00:00:00 2001
From: BuckarooBanzay <BuckarooBanzay@users.noreply.github.com>
Date: Mon, 3 Feb 2020 10:29:20 +0100
Subject: [PATCH] reduce technic_run interval if lag is too high / hot-reload
 offdelay setting / cache-flush command

---
 README.md                                     |  4 +++
 technic/machines/init.lua                     |  1 +
 technic/machines/max_lag.lua                  | 15 +++++++++++
 .../machines/switching_station_globalstep.lua | 27 +++++++++++++++++--
 4 files changed, 45 insertions(+), 2 deletions(-)
 create mode 100644 technic/machines/max_lag.lua

diff --git a/README.md b/README.md
index f144a4e..42e3692 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,10 @@ Recommended mods that build on the `technic mod`:
 * **technic.switch_max_range** max cable length (default: 256)
 * **technic.switch.off_delay_seconds** switching station off delay (default: 300 seconds)
 
+# Chat commands
+
+* **/technic_flush_switch_cache** clears the switching station cache (stops all unloaded switches)
+
 # Open issues
 
 * Documentation (markdown)
diff --git a/technic/machines/init.lua b/technic/machines/init.lua
index 735dc1f..fe087d1 100644
--- a/technic/machines/init.lua
+++ b/technic/machines/init.lua
@@ -7,6 +7,7 @@ dofile(path.."/LV/init.lua")
 dofile(path.."/MV/init.lua")
 dofile(path.."/HV/init.lua")
 
+dofile(path.."/max_lag.lua")
 dofile(path.."/switching_station.lua")
 dofile(path.."/switching_station_globalstep.lua")
 
diff --git a/technic/machines/max_lag.lua b/technic/machines/max_lag.lua
new file mode 100644
index 0000000..af412db
--- /dev/null
+++ b/technic/machines/max_lag.lua
@@ -0,0 +1,15 @@
+local function explode(sep, input)
+        local t={}
+        local i=0
+        for k in string.gmatch(input,"([^"..sep.."]+)") do
+            t[i]=k
+            i=i+1
+        end
+        return t
+end
+
+function technic.get_max_lag()
+	local arrayoutput = explode(", ",minetest.get_server_status())
+	local arrayoutput2 = explode("=",arrayoutput[4])
+	return tonumber(arrayoutput2[1])
+end
diff --git a/technic/machines/switching_station_globalstep.lua b/technic/machines/switching_station_globalstep.lua
index e7ff2aa..8b354a1 100644
--- a/technic/machines/switching_station_globalstep.lua
+++ b/technic/machines/switching_station_globalstep.lua
@@ -44,19 +44,33 @@ minetest.register_abm({
 	end
 })
 
-local off_delay_seconds = tonumber(minetest.settings:get("technic.switch.off_delay_seconds") or "300")
+
+-- the interval between technic_run calls
+local technic_run_interval = 1.0
 
 -- iterate over all collected switching stations and execute the technic_run function
 local timer = 0
 minetest.register_globalstep(function(dtime)
 	timer = timer + dtime
-	if timer < 1.0 then
+	if timer < technic_run_interval then
 		return
 	end
 	timer = 0
 
+	local max_lag = technic.get_max_lag()
+	if max_lag > 1.5 then
+		-- slow down technic execution if the lag is higher than usual
+		technic_run_interval = 1.5
+	else
+		-- normal run_interval
+		technic_run_interval = 1.0
+	end
+
 	local now = minetest.get_us_time()
+
+	local off_delay_seconds = tonumber(minetest.settings:get("technic.switch.off_delay_seconds") or "300")
 	local off_delay_micros = off_delay_seconds*1000*1000
+
 	local active_switches = 0
 
 	for hash, switch in pairs(switches) do
@@ -121,3 +135,12 @@ minetest.register_globalstep(function(dtime)
 
 
 end)
+
+
+minetest.register_chatcommand("technic_flush_switch_cache", {
+	description = "removes all loaded switching stations from the cache",
+	privs = { server = true },
+	func = function()
+		switches = {}
+	end
+})