Builtin: Forward old return values

[minetest.git] / builtin / game / forceloading.lua

diff --git a/builtin/game/forceloading.lua b/builtin/game/forceloading.lua
index 147f12fa074875c2e2bd206d28571355e0b9c763..5de4c3ad34902259c6ab64f8eccfc7dfd336542a 100644 (file)
--- a/builtin/game/forceloading.lua
+++ b/builtin/game/forceloading.lua
@@ -5,9 +5,13 @@ core.forceload_block = nil
 core.forceload_free_block = nil
 
 local blocks_forceloaded
+local blocks_temploaded = {}
 local total_forceloaded = 0
 
-local BLOCKSIZE = 16
+-- true, if the forceloaded blocks got changed (flag for persistence on-disk)
+local forceload_blocks_changed = false
+
+local BLOCKSIZE = core.MAP_BLOCKSIZE
 local function get_blockpos(pos)
        return {
                x = math.floor(pos.x/BLOCKSIZE),
@@ -15,32 +19,58 @@ local function get_blockpos(pos)
                z = math.floor(pos.z/BLOCKSIZE)}
 end
 
-function core.forceload_block(pos)
+-- When we create/free a forceload, it's either transient or persistent. We want
+-- to add to/remove from the table that corresponds to the type of forceload, but
+-- we also need the other table because whether we forceload a block depends on
+-- both tables.
+-- This function returns the "primary" table we are adding to/removing from, and
+-- the other table.
+local function get_relevant_tables(transient)
+       if transient then
+               return blocks_temploaded, blocks_forceloaded
+       else
+               return blocks_forceloaded, blocks_temploaded
+       end
+end
+
+function core.forceload_block(pos, transient)
+       -- set changed flag
+       forceload_blocks_changed = true
+
        local blockpos = get_blockpos(pos)
        local hash = core.hash_node_position(blockpos)
-       if blocks_forceloaded[hash] ~= nil then
-               blocks_forceloaded[hash] = blocks_forceloaded[hash] + 1
+       local relevant_table, other_table = get_relevant_tables(transient)
+       if relevant_table[hash] ~= nil then
+               relevant_table[hash] = relevant_table[hash] + 1
                return true
+       elseif other_table[hash] ~= nil then
+               relevant_table[hash] = 1
        else
-               if total_forceloaded >= (tonumber(core.setting_get("max_forceloaded_blocks")) or 16) then
+               if total_forceloaded >= (tonumber(core.settings:get("max_forceloaded_blocks")) or 16) then
                        return false
                end
                total_forceloaded = total_forceloaded+1
-               blocks_forceloaded[hash] = 1
+               relevant_table[hash] = 1
                forceload_block(blockpos)
                return true
        end
 end
 
-function core.forceload_free_block(pos)
+function core.forceload_free_block(pos, transient)
+       -- set changed flag
+       forceload_blocks_changed = true
+
        local blockpos = get_blockpos(pos)
        local hash = core.hash_node_position(blockpos)
-       if blocks_forceloaded[hash] == nil then return end
-       if blocks_forceloaded[hash] > 1 then
-               blocks_forceloaded[hash] = blocks_forceloaded[hash] - 1
+       local relevant_table, other_table = get_relevant_tables(transient)
+       if relevant_table[hash] == nil then return end
+       if relevant_table[hash] > 1 then
+               relevant_table[hash] = relevant_table[hash] - 1
+       elseif other_table[hash] ~= nil then
+               relevant_table[hash] = nil
        else
                total_forceloaded = total_forceloaded-1
-               blocks_forceloaded[hash] = nil
+               relevant_table[hash] = nil
                forceload_free_block(blockpos)
        end
 end
@@ -53,7 +83,7 @@ local function read_file(filename)
        local t = f:read("*all")
        f:close()
        if t=="" or t==nil then return {} end
-       return core.deserialize(t)
+       return core.deserialize(t) or {}
 end
 
 local function write_file(filename, table)
@@ -74,6 +104,28 @@ core.after(5, function()
        end
 end)
 
-core.register_on_shutdown(function()
+-- persists the currently forceloaded blocks to disk
+local function persist_forceloaded_blocks()
        write_file(wpath.."/force_loaded.txt", blocks_forceloaded)
-end)
+end
+
+-- periodical forceload persistence
+local function periodically_persist_forceloaded_blocks()
+       
+       -- only persist if the blocks actually changed
+       if forceload_blocks_changed then
+               persist_forceloaded_blocks()
+
+               -- reset changed flag
+               forceload_blocks_changed = false
+       end
+
+       -- recheck after some time
+       core.after(10, periodically_persist_forceloaded_blocks)
+end
+
+-- persist periodically
+core.after(5, periodically_persist_forceloaded_blocks)
+
+-- persist on shutdown
+core.register_on_shutdown(persist_forceloaded_blocks)