AutoSave/README.md

AutoSave

Server module for Blockland v21. While you host, it saves every brick on the server to saves/autosave/ on a timer. A save is written a few milliseconds at a time, so the server keeps ticking during a large save.

The files use the stock .bls format and can be loaded from the normal load screen.

Install

Place AutoSave.dll in the game's modules folder, then quit and start Blockland from Steam. A DLL that is already loaded stays mapped until that restart.

AutoSave installs its scripts from a timer on the game's main loop. It does not patch the console's evaluate function, so modules that load after it and look that function up by its first bytes keep working. The console shows AutoSave: /autosaver is ready once the chat command is in.

It only saves while this game is the server: a local single-player or multiplayer host, or a dedicated server.

Files

Each save is named for the local time it started, for example saves/autosave/2026-10-26 00-29-28.bls. Windows does not allow colons in file names, so the time uses hyphens; the description line inside the file uses colons. If a file with that name already exists, (2), (3) and so on is added.

The save is written to saves/autosave/writing.bls.tmp and renamed when it is complete, so a crash or cancel never leaves a half-written .bls. Old autosaves are not deleted.

$pref::SaveOwnership and $pref::SaveExtendedBrickInfo are followed the same way the stock save follows them.

Preview picture

Each save gets a picture next to it with the same name, for example saves/autosave/2026-10-26 00-29-28.jpg. That is the file the load screen shows for a save.

The picture comes from the server preview: the overhead view the game traces for the server list. It is a 768x768 image traced a few pixels per tick on the server, so it works on a dedicated server with no camera. A preview centered with /setPreviewCenter keeps that center.

• The engine traces at most 128 pixels per tick. While a picture is wanted, AutoSave also traces pixels itself through the same engine function, 6 ms at a time with a 12 ms pause, and stops while a save is being written. The engine traces the last pixel, so its normal finish still produces the image.
• If nothing is tracing, AutoSave starts the tracer at the engine's top rate (128 work per tick instead of the default 64). When the picture is done, AutoSave stops the tracer, puts the rate back, and nothing is uploaded.
• If the game is already tracing its own preview (an internet server does this all the time), AutoSave helps that image along and keeps a copy. The game's upload to the server list is not changed.
• The console shows the progress every 30 seconds and the time taken, and the chat says when the picture is saved. If the game quits first, that save has no picture. Clearing all bricks stops the tracer, so that save has no picture either.
• If another save finishes while a picture is still being traced, the picture goes to the newest save.

/autosaver screenshot off turns this off. The setting is saved with the other prefs, so it stays off after a restart.

When it saves

The first save after starting always runs. After that, a save is skipped if nothing changed. Planting, loading, removing or killing a brick counts as a change. So does adding or clearing events, renaming a brick, and changing its color, paint effect, shape effect, print, collision, raycasting, rendering, light, emitter, item, music, sound or vehicle.

While bricks are loading, the per-brick change checks are skipped, and a finished or cancelled load counts as one change.

The game turns off packages added after the client add-ons when a server shuts down, which includes AutoSave's change watcher. AutoSave installs it again afterwards, and the first save on each new server always runs.

A save is also skipped while bricks are loading, while bricks are being cleared, and while the mission is being cleaned up. If a load or a clear starts in the middle of a save, the save stops, its temp file is removed, and the next interval tries again.

Large builds

Each slice handles up to the chunk size and stops after 8 ms, then waits at least 12 ms before the next slice. Progress is written to the console every 2 seconds.

Brick values the stock loader sets as fields (angle, baseplate, color, print, color and shape effect, position) are read as fields instead of through method calls. Field names are looked up once, and each datablock's name and print flag are cached per save. The first 64 bricks of each save are also read through the methods; if anything differs, the console says so and the methods are used until the game restarts.

Up to 75000 bricks, bricks are sorted by height like the stock save. Over 75000, the sort and the wrench-extras pass are skipped and the file is written in one pass. The brick count in the header is filled in when the write finishes.

Chat commands

/as is short for /autosaver and works with every command below, for example /as save or /as load 08-55-15.

Anyone can use:

• /autosaver help
• /autosaver status

Admins can use:

• /autosaver on and /autosaver off
• /autosaver save (or now): save right away
• /autosaver load (or reload): clear all bricks, then load the newest file in saves/autosave/
• /autosaver load <name>: clear all bricks, then load that autosave instead, for example /autosaver load 2026-10-26 08-55-15
• /autosaver interval <seconds>: 30 to 86400, default 300
• /autosaver chunk <bricks>: bricks per slice, 1 to 20000, default 4000
• /autosaver tick <milliseconds>: pause between slices, 1 to 1000, default 1 (never less than 12 ms in practice)
• /autosaver screenshot on or off (also screenshots or preview): picture for each save, default on
• /autosaver autoload on or off: load the newest autosave when a server starts, default off

Out-of-range values are clamped. Changes are announced to everyone and saved right away.

load with no name uses the file with the newest modified time on disk, including saves made since the game started. With a name, .bls is optional, case does not matter, and any part of the name works if only one autosave matches it (/autosaver load 08-55-15). If several match, nothing is cleared and you are told how many. Names cannot point outside saves/autosave/. Either way it loads with saved ownership and exact colors. The command is case-insensitive.

Autoload

With autoload on, the newest file in saves/autosave/ is loaded when a server starts, with saved ownership and exact colors, the same as /autosaver load. It waits until the mission is running. It is skipped, with a console line saying why, when:

• a game mode is running (game modes bring their own build);
• a save was picked when the server was set up, or bricks are already loaded or loading;
• there is no autosave.

The loaded build counts as already saved, so the next interval does not write the same build again.

Preferences

Settings are server prefs, stored in config/server/prefs.cs with the game's other server prefs:

$Pref::Server::AutoSave::AutoLoad = 0;
$Pref::Server::AutoSave::Chunk = 4000;
$Pref::Server::AutoSave::Enabled = 1;
$Pref::Server::AutoSave::Interval = 300;
$Pref::Server::AutoSave::Preview = 1;
$Pref::Server::AutoSave::Tick = 1;

They are read each time a server starts. AutoSave checks every 5 seconds for a new server, which it tells apart by the mission's MissionGroup, so stopping one server and starting another is noticed even within one save interval. The save timer restarts with each new server. If a pref is missing, the default is used and added to the file the next time the game writes its prefs.

Every /autosaver on, off, interval, chunk, tick, screenshot and autoload writes prefs.cs right away, using the same export the game runs when custom game settings change. AutoSave only writes the file while a server is running, after the game has loaded it, so other prefs are kept. You can also edit the lines while the game is closed. Values out of range are clamped the same way as in chat.

Console

• autoSave() starts a save now
• autoSaveNewest() returns the newest autosave path
• autoSaveFind(name) returns the autosave path for a name, *N if N files match, or nothing
• autoSaveApply() clamps the settings, copies them to $Pref::Server::AutoSave::*, writes config/server/prefs.cs while hosting, and restarts the timer
• $AutoSave::Enabled, $AutoSave::Interval, $AutoSave::Chunk, $AutoSave::Tick, $AutoSave::Preview, $AutoSave::AutoLoad are the live values

A value set on $AutoSave::* in the console is not saved, and a new interval does not take effect, until autoSaveApply() is called.

Build

Blockland is a 32-bit program, so the DLL has to be built with a 32-bit MinGW toolchain (i686-w64-mingw32). Put that toolchain's bin directory first on PATH so CMake finds that gcc and mingw32-make.

find_package(TSFUNCS) needs a tsfuncs 1.0.1 package: tsfuncs-config.cmake next to include/ and lib/. MinHook's cmake package lives under that package's lib/minhook. Pass the package directory as CMAKE_PREFIX_PATH.

From this repo:

cmake -G "MinGW Makefiles" -DCMAKE_BUILD_TYPE=Release -DCMAKE_POLICY_VERSION_MINIMUM=3.5 -DCMAKE_PREFIX_PATH=C:/path/to/tsfuncs -S . -B build
cmake --build build

The result is build/AutoSave.dll. CMa