stabilize, add daemon state, add base build script

instance/src/lib/utils.ts

@@ -1,5 +1,6 @@
 import { TextLineStream } from "https://deno.land/std@0.208.0/streams/mod.ts";
 
+export type Channel<T> = ReturnType<typeof channel<T>>;
 export function channel<T>() {
 	const inner = {
 		queue: [] as T[],
@@ -41,3 +42,54 @@ export function lines(readable: ReadableStream<Uint8Array>) {
 		.pipeThrough(new TextDecoderStream())
 		.pipeThrough(new TextLineStream());
 }
+
+const async_noop = async () => {};
+export type LoopProcess = ReturnType<typeof loop_process>;
+export function loop_process(
+	command: Deno.Command,
+	opts?: { delay?: number; on_start?: () => unknown; on_stop?: () => unknown },
+) {
+	const events = {
+		on_start: opts?.on_start ?? async_noop,
+		on_stop: opts?.on_stop ?? async_noop,
+	};
+	const kill_sig = channel<"kill">();
+	async function launch() {
+		while (true) {
+			await events.on_start();
+			const child_process = command.spawn();
+			const result = await Promise.any([kill_sig.receive(), child_process.output()]);
+			if (result === "kill") {
+				await events.on_stop();
+				child_process.kill();
+				break;
+			}
+			await events.on_stop();
+			await sleep(opts?.delay ?? 500);
+		}
+	}
+	const looping = launch();
+	return {
+		kill: async () => {
+			kill_sig.send("kill"), await looping;
+		},
+		events,
+		looping,
+	};
+}
+
+export function sleep(ms: number) {
+	return new Promise((resolver) => setTimeout(resolver, ms));
+}
+
+export async function run(command: string, ...args: string[]) {
+	const { code } = await new Deno.Command(command, { args }).output();
+	if (code != 0) throw new Error(`command ${command} failed`);
+}
+
+export function log_from(...prefixes: string[]) {
+	const prefix = prefixes.map((p) => `[${p}]`).join("").padStart(10);
+	return function (...args: unknown[]) {
+		console.log(prefix, ...args);
+	};
+}