io: add storage helper

Use bincode+zstd to serialize data structures for temporary storage.

src/io/mod.rs

@@ -1,2 +1,3 @@
 pub mod data;
 pub mod region;
+pub mod storage;

src/io/storage.rs

@@ -0,0 +1,22 @@
+use std::{
+	fs::File,
+	io::{BufWriter, Write},
+	path::Path,
+};
+
+use anyhow::{Context, Result};
+use serde::Serialize;
+
+pub fn write<T: Serialize>(path: &Path, value: &T) -> Result<()> {
+	(|| -> Result<()> {
+		let file = File::create(path)?;
+		let writer = BufWriter::new(file);
+		let mut compressor = zstd::Encoder::new(writer, 1)?;
+		bincode::serialize_into(&mut compressor, value)?;
+		let writer = compressor.finish()?;
+		let mut file = writer.into_inner()?;
+		file.flush()?;
+		Ok(())
+	})()
+	.with_context(|| format!("Failed to write file {}", path.display()))
+}