minedmap: add support for parallel processing

For now, only RegionProcessor and TileMipmapper are run in parallel.

src/bin/minedmap/main.rs

@@ -7,7 +7,7 @@ mod tile_renderer;
 
 use std::path::PathBuf;
 
-use anyhow::Result;
+use anyhow::{Context, Result};
 use clap::Parser;
 
 use common::Config;
@@ -18,15 +18,30 @@ use tile_renderer::TileRenderer;
 
 #[derive(Debug, Parser)]
 pub struct Args {
+	/// Number of parallel threads to use for processing
+	///
+	/// If not given, only a single thread is used. Pass 0 to
+	/// use one thread per logical CPU core.
+	#[arg(short, long)]
+	pub jobs: Option<usize>,
 	/// Minecraft save directory
 	pub input_dir: PathBuf,
 	/// MinedMap data directory
 	pub output_dir: PathBuf,
 }
 
+fn setup_threads(num_threads: usize) -> Result<()> {
+	rayon::ThreadPoolBuilder::new()
+		.num_threads(num_threads)
+		.build_global()
+		.context("Failed to configure thread pool")
+}
+
 fn main() -> Result<()> {
 	let args = Args::parse();
-	let config = Config::new(args);
+	let config = Config::new(&args);
+
+	setup_threads(config.num_threads)?;
 
 	let regions = RegionProcessor::new(&config).run()?;
 	TileRenderer::new(&config).run(&regions)?;