Forceloading: Transient forceloads

Adds a flag to forceload_block which lets you turn off persistence for
that forceload.

diff --git a/builtin/game/forceloading.lua b/builtin/game/forceloading.lua
index 468572e6e641dd7edade74df4b7376dc503c7445..8a05de36c08dca1ff3cfd06feb0469841731c788 100644 (file)
--- a/builtin/game/forceloading.lua
+++ b/builtin/game/forceloading.lua
@@ -5,6 +5,7 @@ core.forceload_block = nil
 core.forceload_free_block = nil
 
 local blocks_forceloaded
+local blocks_temploaded = {}
 local total_forceloaded = 0
 
 local BLOCKSIZE = core.MAP_BLOCKSIZE
@@ -15,32 +16,52 @@ 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)
        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
                        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)
        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

diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index e0e984c0f10d054e2715eb23134fc26cbdada7b3..c82027148054e51bac229c5aceff99eab768202f 100644 (file)
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -2622,13 +2622,17 @@ These functions return the leftover itemstack.
        the creative mode setting, and checks for "sneak" to set the `invert_wall`
        parameter.
 
-* `minetest.forceload_block(pos)`
+* `minetest.forceload_block(pos[, transient])`
     * forceloads the position `pos`.
     * returns `true` if area could be forceloaded
-    * Please note that forceloaded areas are saved when the server restarts.
+    * If `transient` is `false` or absent, the forceload will be persistent
+      (saved between server runs). If `true`, the forceload will be transient
+      (not saved between server runs).
 
-* `minetest.forceload_free_block(pos)`
+* `minetest.forceload_free_block(pos[, transient])`
     * stops forceloading the position `pos`
+    * If `transient` is `false` or absent, frees a persistent forceload.
+      If `true`, frees a transient forceload.
 
 * `minetest.request_insecure_environment()`: returns an environment containing
   insecure functions if the calling mod has been listed as trusted in the