crossbeam_channel::tick delivery_time can support different flavor

[tisonkun]

Currently, the new delivery_time is calculated as:

crossbeam/crossbeam-channel/src/flavors/tick.rs

Lines 47 to 50 in dfafb46

	if self
	.delivery_time
	.compare_exchange(delivery_time, now + self.duration)
	.is_ok()

But it can be a flavor config like Java's ScheduledExecutorService: scheduleAtFixedRate and scheduleWithFixedDelay.

The current flavor is in scheduleWithFixedDelay, while replace now + self.duration with delivery_time + self.duration can simulate scheduleAtFixedRate as much as possible.

To consume multiple ticks backlog, one can use try_iter and then collect.

Let me know if it's a good idea to follow. cc @taiki-e

[taiki-e]

What API are you proposing to add?

[tisonkun]

@taiki-e that's the next step. If the semantic is good to have, I think the best way to express the API is by submitting a patch :D

I file this issue first to avoid wasting time on patches that would never be accepted.

[taiki-e]

I didn't mean to ask you to create a patch before the discussion about API, I wanted to know what you are imagining it would look like if it were expressed as an API in Rust.

I guess what you are actually requesting here is something like tokio::time::interval, but tokio::time::interval also has an API to tune the behavior.

[tisonkun]

@taiki-e Thanks for your information!

Yes, it seems like tokio::time::interval while I don't find your comment "has an API to tune the behavior". It seems that struct has only a period arg to define the interval.

For API in crossbeam channel, the whole structure can be identical to tick with different rules for calculating delivery_time, i.e.,

• for try_recv, it's delivery_time + self.duration over now + self.duration.
• for recv, it's delivery_time + self.duration over delivery_time.max(now) + self.duration.

If we agree on reuse the structure, it can be a different API on crossbeam_channel to switch the flavor,

• tick_with_delay supersedes the current manner;
• tick_with_interval indicates the proposed manner.