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author | orwell96 <orwell@bleipb.de> | 2020-12-16 16:33:41 +0100 |
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committer | orwell96 <orwell@bleipb.de> | 2021-01-12 13:27:00 +0100 |
commit | e6b656e93723ea2f0d36c8da39baba4fa099d711 (patch) | |
tree | 375fba212a1a09c707b98a4b288aee31a61157b6 /serialize_lib/init.lua | |
parent | bdc49b919d5480ef3fef1ea415caadd8408cf35d (diff) | |
download | advtrains-e6b656e93723ea2f0d36c8da39baba4fa099d711.tar.gz advtrains-e6b656e93723ea2f0d36c8da39baba4fa099d711.tar.bz2 advtrains-e6b656e93723ea2f0d36c8da39baba4fa099d711.zip |
Implement basic serialization and file opening
Diffstat (limited to 'serialize_lib/init.lua')
-rw-r--r-- | serialize_lib/init.lua | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/serialize_lib/init.lua b/serialize_lib/init.lua new file mode 100644 index 0000000..7a1a10b --- /dev/null +++ b/serialize_lib/init.lua @@ -0,0 +1,92 @@ +-- serialize_lib +--[[ + Copyright (C) 2020 Moritz Blei (orwell96) and contributors + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU Affero General Public License as + published by the Free Software Foundation, either version 3 of the + License, or (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU Affero General Public License for more details. +]]-- + +serialize_lib = {} + +--[[ Configuration table +Whenever asked for a "config", the following table structure is expected: +config = { + skip_empty_tables = false -- if true, does not store empty tables + -- On next read, keys that mapped to empty tables resolve to nil + -- Used by: write_table_to_file +} +Not all functions use all of the parameters, so you can simplify your config sometimes +]] + +-- log utils +-- ========= + + +function serialize_lib.log_error(text) + minetest.log("error", "[serialize_lib] "..text) +end +function serialize_lib.log_warn(text) + minetest.log("warning", "[serialize_lib] "..text) +end +function serialize_lib.log_info(text) + minetest.log("action", "[serialize_lib] "..text) +end +function serialize_lib.log_debug(text) + minetest.log("action", "[serialize_lib](debug) "..text) +end + +-- basic serialization/deserialization +-- =================================== + +local ser = dofile("serialize.lua") + +-- Opens the passed filename, and returns deserialized table +-- When an error occurs, logs an error and returns false +function serialize_lib.read_table_from_file(filename) + local succ, err = pcall(ser.read_from_file, filename) + if not succ then + serialize_lib.log_error("Mod '"..minetest.get_current_modname().."': "..err) + end + return succ +end + +-- Writes table into file +-- When an error occurs, logs an error and returns false +function serialize_lib.write_table_to_file(filename) + local succ, err = pcall(ser.write_to_file, filename) + if not succ then + serialize_lib.log_error("Mod '"..minetest.get_current_modname().."': "..err) + end + return succ +end + +-- Managing files and backups +-- ========================== + +--[[ +The plain scheme just overwrites the file in place. This however poses problems when we are interrupted right within +the write, so we have incomplete data. So, the following scheme is applied: +1. writes to <filename>.new (if .new already exists, try to complete the moving first) +2. moves <filename> to <filename>.old, possibly overwriting an existing file (special windows behavior) +3. moves <filename>.new to <filename> + +During loading, we apply the following order of precedence: +1. <filename>.new +2. <filename> +3. <filename>.old + +Normal case: <filename> and <filename>.old exist, loading <filename> +Interrupted during write: .new is damaged, loads last regular state +Interrupted during the move operations: either <filename>.new or <filename> represents the latest state +Other corruption: at least the .old state may still be present + +]]-- + + |