minedmap: skip generation steps when the inputs are unchanged

src/bin/minedmap/region_processor.rs

@@ -66,43 +66,46 @@ impl<'a> RegionProcessor<'a> {
 	}
 
 	fn save_region(
-		&self,
-		coords: TileCoords,
+		path: &Path,
 		processed_region: &ProcessedRegion,
 		timestamp: SystemTime,
 	) -> Result<()> {
-		let output_path = self.config.processed_path(coords);
-		storage::write(&output_path, processed_region, FILE_META_VERSION, timestamp)
+		storage::write(path, processed_region, FILE_META_VERSION, timestamp)
 	}
 
 	fn save_lightmap(
-		&self,
-		coords: TileCoords,
+		path: &Path,
 		lightmap: &image::GrayAlphaImage,
 		timestamp: SystemTime,
 	) -> Result<()> {
-		fs::create_with_timestamp(
-			&self.config.tile_path(TileKind::Lightmap, 0, coords),
-			FILE_META_VERSION,
-			timestamp,
-			|file| {
-				lightmap
-					.write_to(file, image::ImageFormat::Png)
-					.context("Failed to save image")
-			},
-		)
+		fs::create_with_timestamp(path, FILE_META_VERSION, timestamp, |file| {
+			lightmap
+				.write_to(file, image::ImageFormat::Png)
+				.context("Failed to save image")
+		})
 	}
 
 	/// Processes a single region file
 	fn process_region(&self, path: &Path, coords: TileCoords) -> Result<()> {
 		const N: u32 = (BLOCKS_PER_CHUNK * CHUNKS_PER_REGION) as u32;
 
-		println!("Processing region r.{}.{}.mca", coords.x, coords.z);
-
 		let mut processed_region = ProcessedRegion::default();
 		let mut lightmap = image::GrayAlphaImage::new(N, N);
 
-		let timestamp = fs::modified_timestamp(path)?;
+		let input_timestamp = fs::modified_timestamp(path)?;
+
+		let output_path = self.config.processed_path(coords);
+		let output_timestamp = fs::read_timestamp(&output_path, FILE_META_VERSION);
+		let lightmap_path = self.config.tile_path(TileKind::Lightmap, 0, coords);
+		let lightmap_timestamp = fs::read_timestamp(&lightmap_path, FILE_META_VERSION);
+
+		if Some(input_timestamp) <= output_timestamp && Some(input_timestamp) <= lightmap_timestamp
+		{
+			println!("Skipping unchanged region r.{}.{}.mca", coords.x, coords.z);
+			return Ok(());
+		}
+
+		println!("Processing region r.{}.{}.mca", coords.x, coords.z);
 
 		minedmap::io::region::from_file(path)?.foreach_chunk(
 			|chunk_coords, data: world::de::Chunk| {
@@ -125,8 +128,12 @@ impl<'a> RegionProcessor<'a> {
 			},
 		)?;
 
-		self.save_region(coords, &processed_region, timestamp)?;
-		self.save_lightmap(coords, &lightmap, timestamp)?;
+		if Some(input_timestamp) > output_timestamp {
+			Self::save_region(&output_path, &processed_region, input_timestamp)?;
+		}
+		if Some(input_timestamp) > lightmap_timestamp {
+			Self::save_lightmap(&lightmap_path, &lightmap, input_timestamp)?;
+		}
 
 		Ok(())
 	}

src/bin/minedmap/tile_mipmapper.rs

@@ -49,17 +49,7 @@ impl<'a> TileMipmapper<'a> {
 		const N: u32 = (BLOCKS_PER_CHUNK * CHUNKS_PER_REGION) as u32;
 
 		let output_path = self.config.tile_path(kind, level, coords);
-
-		println!(
-			"Rendering mipmap tile {}",
-			output_path
-				.strip_prefix(&self.config.output_dir)
-				.expect("tile path must be in output directory")
-				.display(),
-		);
-
-		let mut image: image::DynamicImage =
-			image::ImageBuffer::<P, Vec<P::Subpixel>>::new(N, N).into();
+		let output_timestamp = fs::read_timestamp(&output_path, FILE_META_VERSION);
 
 		let sources: Vec<_> = [(0, 0), (0, 1), (1, 0), (1, 1)]
 			.into_iter()
@@ -84,10 +74,32 @@ impl<'a> TileMipmapper<'a> {
 			})
 			.collect();
 
-		let Some(timestamp) = sources.iter().map(|(_, _, ts)| *ts).max() else {
+		let Some(input_timestamp) = sources.iter().map(|(_, _, ts)| *ts).max() else {
 			return Ok(());
 		};
 
+		if Some(input_timestamp) <= output_timestamp {
+			println!(
+				"Skipping unchanged mipmap tile {}",
+				output_path
+					.strip_prefix(&self.config.output_dir)
+					.expect("tile path must be in output directory")
+					.display(),
+			);
+			return Ok(());
+		}
+
+		println!(
+			"Rendering mipmap tile {}",
+			output_path
+				.strip_prefix(&self.config.output_dir)
+				.expect("tile path must be in output directory")
+				.display(),
+		);
+
+		let mut image: image::DynamicImage =
+			image::ImageBuffer::<P, Vec<P::Subpixel>>::new(N, N).into();
+
 		for ((dx, dz), source_path, _) in sources {
 			let source = match image::open(&source_path) {
 				Ok(source) => source,
@@ -109,7 +121,7 @@ impl<'a> TileMipmapper<'a> {
 			);
 		}
 
-		fs::create_with_timestamp(&output_path, FILE_META_VERSION, timestamp, |file| {
+		fs::create_with_timestamp(&output_path, FILE_META_VERSION, input_timestamp, |file| {
 			image
 				.write_to(file, image::ImageFormat::Png)
 				.context("Failed to save image")

src/bin/minedmap/tile_renderer.rs

@@ -1,4 +1,4 @@
-use std::time::SystemTime;
+use std::path::Path;
 
 use anyhow::{Context, Result};
 
@@ -19,12 +19,8 @@ impl<'a> TileRenderer<'a> {
 		TileRenderer { config }
 	}
 
-	fn load_region(&self, coords: TileCoords) -> Result<(ProcessedRegion, SystemTime)> {
-		let processed_path = self.config.processed_path(coords);
-		let timestamp = fs::modified_timestamp(&processed_path)?;
-		let region =
-			storage::read(&processed_path).context("Failed to load processed region data")?;
-		Ok((region, timestamp))
+	fn load_region(processed_path: &Path) -> Result<ProcessedRegion> {
+		storage::read(processed_path).context("Failed to load processed region data")
 	}
 
 	fn render_chunk(image: &mut image::RgbaImage, coords: ChunkCoords, chunk: &ProcessedChunk) {
@@ -64,7 +60,22 @@ impl<'a> TileRenderer<'a> {
 	fn render_tile(&self, coords: TileCoords) -> Result<()> {
 		const N: u32 = (BLOCKS_PER_CHUNK * CHUNKS_PER_REGION) as u32;
 
+		let processed_path = self.config.processed_path(coords);
+		let processed_timestamp = fs::modified_timestamp(&processed_path)?;
+
 		let output_path = self.config.tile_path(TileKind::Map, 0, coords);
+		let output_timestamp = fs::read_timestamp(&output_path, FILE_META_VERSION);
+
+		if Some(processed_timestamp) <= output_timestamp {
+			println!(
+				"Skipping unchanged tile {}",
+				output_path
+					.strip_prefix(&self.config.output_dir)
+					.expect("tile path must be in output directory")
+					.display(),
+			);
+			return Ok(());
+		}
 
 		println!(
 			"Rendering tile {}",
@@ -74,15 +85,20 @@ impl<'a> TileRenderer<'a> {
 				.display(),
 		);
 
-		let (region, timestamp) = self.load_region(coords)?;
+		let region = Self::load_region(&processed_path)?;
 		let mut image = image::RgbaImage::new(N, N);
 		Self::render_region(&mut image, &region);
 
-		fs::create_with_timestamp(&output_path, FILE_META_VERSION, timestamp, |file| {
-			image
-				.write_to(file, image::ImageFormat::Png)
-				.context("Failed to save image")
-		})
+		fs::create_with_timestamp(
+			&output_path,
+			FILE_META_VERSION,
+			processed_timestamp,
+			|file| {
+				image
+					.write_to(file, image::ImageFormat::Png)
+					.context("Failed to save image")
+			},
+		)
 	}
 
 	pub fn run(self, regions: &[TileCoords]) -> Result<()> {

src/io/fs.rs

@@ -6,12 +6,12 @@ use std::{
 };
 
 use anyhow::{Context, Ok, Result};
-use serde::Serialize;
+use serde::{Deserialize, Serialize};
 
-#[derive(Debug, Clone, Copy, Serialize)]
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
 pub struct FileMetaVersion(pub u32);
 
-#[derive(Debug, Serialize)]
+#[derive(Debug, Serialize, Deserialize)]
 struct FileMeta {
 	version: FileMetaVersion,
 	timestamp: SystemTime,
@@ -115,6 +115,18 @@ pub fn modified_timestamp(path: &Path) -> Result<SystemTime> {
 		})
 }
 
+pub fn read_timestamp(path: &Path, version: FileMetaVersion) -> Option<SystemTime> {
+	let meta_path = metafile_name(path);
+	let mut file = BufReader::new(fs::File::open(meta_path).ok()?);
+
+	let meta: FileMeta = serde_json::from_reader(&mut file).ok()?;
+	if meta.version != version {
+		return None;
+	}
+
+	Some(meta.timestamp)
+}
+
 pub fn create_with_timestamp<T, F>(
 	path: &Path,
 	version: FileMetaVersion,