Heartbeat Checkpoint

[thantos]

workflow(() => {
	const act = act1();

    act.onHeartbeat(async ({ i: 100 }) => {
	    await reportProgress(i);
    });
});

const reportProceess = activity(...);

const act1 = activity<{ result: string }, { i: 100 } | undefined>({
   heartbeat: { seconds: 20 },
   timeout: { seconds: 160 }
}, (context: Context): { result: string } | AsyncToken => {
   ...doSomeWork...

   await sendToQueue({ token: context.activity.token, start: context.checkpoint });

	// should this be on the context to be typed?
   await sendHeartbeat();

   return makeAsync();
})

// lambda function consuming the queue
const workflowClient = new WorkflowClient();
export const handler = async (event) => {
    Promise.all(event.Records.map(async (record) => {
        const payload = JSON.parse(record.body);

		const items = [...];

		const start = event.start ?? 0;

		for(const i of items.slice()) {
		   // some long process
		   await workflowClient.heartbeatActivity<typeof act1>(
			   payload.token,
			   { i }
		   );
		}
        
        // complete the activity with a payload
	    await workflowClient.completeActivity<typeof act1>(
		    payload.token,
		    { result: "done"}
		);
    }));
}

[thantos]

https://github.com/functionless/eventual/issues/60