Support Reactive One-Time Tokens in a Clustered Environment

[franticticktick]

To support reactive one-time token login for a clustered environment, need to implement R2dbcReactiveOneTimeTokenService or something like this.

[jzheaux]

Agreed, @franticticktick. Are you able to submit a PR to add this?

[franticticktick]

Hi @jzheaux , I will be submitting a PR in the next couple of days, could you assign this issue to me please?

[franticticktick]

@jzheaux I would like to ask you for advice, I’m not sure how best to implement the ability to delete expired tokens.
JdbcOneTimeTokenService has a taskScheduler that does the cleanup:

	private ThreadPoolTaskScheduler createTaskScheduler(String cleanupCron) {
		if (cleanupCron == null) {
			return null;
		}
		ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
		taskScheduler.setThreadNamePrefix("spring-one-time-tokens-");
		taskScheduler.initialize();
		taskScheduler.schedule(this::cleanupExpiredTokens, new CronTrigger(cleanupCron));
		return taskScheduler;
	}

For R2dbcReactiveOneTimeTokenService I can try to implement this via Flux.interval or Scheduler.schedulePeriodically but this does not provide the same API as JdbcOneTimeTokenService. Maybe we should suggest calling the cleanupExpiredTokens method in a background task in the client code?