Code examples of Deno Queues

deno-queues-examples.ts

// https://deno.com/blog/queues

function listenQueue<T>(fn: (msg: T) => Promise<void>) {
  //
}


// lib/kv/queue/_core.ts
const messageTypes = {
  foo: "foo",
  bar: "bar",
} as const;

type MessageType = (typeof messageTypes)[keyof typeof messageTypes];

type Message = {
  type: MessageType;
  payload?: unknown;
};

type HandlerFunc = (msg: Message) => void | Promise<void>;

type Handler = {
  type: MessageType;
  run: HandlerFunc;
};


// lib/kv/queue/foo.handler.ts
const fooHandler: Handler = {
  type: messageTypes.foo,

  run: async (msg) => {
  // asserts payload is XXX;

  console.log("foo", msg);
}};


// lib/kv/queue/bar.handler.ts
const barHandler: Handler = {
  type: messageTypes.bar,

  run: async (msg) => {
    // asserts payload is XXX;

    console.log("bar", msg);
  },
};


// lib/kv/queue/mod.ts
const handlers = new Map<MessageType, Handler>();
handlers.set(fooHandler.type, fooHandler);
handlers.set(fooHandler.type, barHandler);


// main.ts
listenQueue<Message>(async (msg) => {
  const h = handlers.get(msg.type);
  if (!h) {
    console.error(`Unknown message: msg.type=${msg.type}`, msg);
    return;
  }

  await h.run(msg);
});