From 04c78373f1db0b011557b92cd6fb58268cbeefe4 Mon Sep 17 00:00:00 2001
From: orwell96 <orwell@bleipb.de>
Date: Wed, 17 Feb 2021 19:45:52 +0100
Subject: [PATCH] LuaATC: add interrupt_safe() and clear_interrupts(), fix
 queue mainloop

---
 advtrains_luaautomation/README.md         | 15 +++++++++-
 advtrains_luaautomation/active_common.lua | 12 ++++++++
 advtrains_luaautomation/interrupt.lua     | 35 +++++++++++++++++++----
 3 files changed, 56 insertions(+), 6 deletions(-)

diff --git a/advtrains_luaautomation/README.md b/advtrains_luaautomation/README.md
index c8fb7fe..5232c22 100644
--- a/advtrains_luaautomation/README.md
+++ b/advtrains_luaautomation/README.md
@@ -20,6 +20,13 @@ Create environment with the given name. To be able to do anything, you first nee
  - `/env_setup <env_name>`:
 Invoke the form to edit the environment's initialization code. For more information, see the section on active components. You can also delete an environment from here.
 
+ - `/env_subscribe <env_name>`, `/env_unsubscribe <env_name>`:
+Subscribe or unsubscribe from log/error messages originating from this environment
+
+ - `/env_subscriptions [env_name]`:
+List your subscriptions or players subscribed to an environment.
+
+
 ## Functions and variables
 ### General Functions and Variables
 The following standard Lua libraries are available:
@@ -71,11 +78,17 @@ Set the state of the passive component at position `pos`.
 Checks whether there is a passive component at the position pos (and/or whether a passive component with this name exists)
 
  - `interrupt(time, message)`
-Cause LuaAutomation to trigger an `int` event on this component after the given time in seconds with the specified `message` field. `message` can be of any Lua data type. *Not available in init code.*
+Cause LuaAutomation to trigger an `int` event on this component after the given time in seconds with the specified `message` field. `message` can be of any Lua data type. Returns true. *Not available in init code.*
+
+ - `interrupt_safe(time, message)`
+Like `interrupt()`, but does not add an interrupt and returns false when an interrupt (of any type) is already present for this component. Returns true when interrupt was successfully added.
 
  - `interrupt_pos(pos, message)`
 Immediately trigger an `ext_int` event on the active component at position pos. `message` is like in interrupt(). Use with care, or better **_don't use_**! Incorrect use can result in **_expotential growth of interrupts_**.
 
+ - `clear_interrupts()`
+Removes any pending interrupts of this node.
+
  - `digiline_send(channel, message)`
 Make this active component send a digiline message on the specified channel.
 Not available in init code.
diff --git a/advtrains_luaautomation/active_common.lua b/advtrains_luaautomation/active_common.lua
index f06eb51..d168bad 100644
--- a/advtrains_luaautomation/active_common.lua
+++ b/advtrains_luaautomation/active_common.lua
@@ -122,6 +122,18 @@ function ac.run_in_env(pos, evtdata, customfct_p)
 		assert(t >= 0)
 		atlatc.interrupt.add(t, pos, {type="int", int=true, message=imesg, msg=imesg}) --Compatiblity "message" field.
 	end
+	customfct.interrupt_safe=function(t, imesg)
+		assertt(t, "number")
+		assert(t >= 0)
+		if atlatc.interrupt.has_at_pos(pos) then
+			return false
+		end
+		atlatc.interrupt.add(t, pos, {type="int", int=true, message=imesg, msg=imesg}) --Compatiblity "message" field.
+		return true
+	end
+	customfct.clear_interrupts=function()
+		atlatc.interrupt.clear_ints_at_pos(pos)
+	end
 	-- add digiline_send function, if digiline is loaded
 	if minetest.global_exists("digiline") then
 		customfct.digiline_send=function(channel, msg)
diff --git a/advtrains_luaautomation/interrupt.lua b/advtrains_luaautomation/interrupt.lua
index 525c3b4..2e54ad8 100644
--- a/advtrains_luaautomation/interrupt.lua
+++ b/advtrains_luaautomation/interrupt.lua
@@ -16,6 +16,30 @@ function iq.save()
 	return {queue = queue, timer=timer}
 end
 
+function iq.has_at_pos(pos)
+	for i=1,#queue do
+		local qe=queue[i]
+		if vector.equals(pos, qe.p) then
+			return true
+		end
+	end
+	return false
+end
+
+function iq.clear_ints_at_pos(pos)
+	local i=1
+	while i<=#queue do
+		local qe=queue[i]
+		if not qe then
+			table.remove(queue, i)
+		elseif vector.equals(pos, qe.p) and (qe.e.int or qe.e.ext_int) then
+			table.remove(queue, i)
+		else
+			i=i+1
+		end
+	end
+end
+
 function iq.add(t, pos, evtdata)
 	queue[#queue+1]={t=t+timer, p=pos, e=evtdata}
 	run=true
@@ -23,13 +47,14 @@ end
 
 function iq.mainloop(dtime)
 	timer=timer + math.min(dtime, 0.2)
-	for i=1,#queue do
+	local i=1
+	while i<=#queue do
 		local qe=queue[i]
 		if not qe then
 			table.remove(queue, i)
-			i=i-1
 		elseif timer>qe.t then
-			local pos, evtdata=queue[i].p, queue[i].e
+			table.remove(queue, i)
+			local pos, evtdata=qe.p, qe.e
 			local node=advtrains.ndb.get_node(pos)
 			local ndef=minetest.registered_nodes[node.name]
 			if ndef and ndef.luaautomation and ndef.luaautomation.fire_event then
@@ -37,8 +62,8 @@ function iq.mainloop(dtime)
 			else
 				atwarn("[atlatc][interrupt] Couldn't run event",evtdata.type,"on",pos,", something wrong with the node",node)
 			end
-			table.remove(queue, i)
-			i=i-1
+		else
+			i=i+1
 		end
 	end
 end