Fixes a default config bug of gc scheduler

[miaoyq]

I ran the containerd service with the default config, the service failed when loading config file with error log:

containerd[10993]: containerd: time: missing unit in duration 100000000

That's because toml.Decode can not decode 100000000 to time.Duration variable.

We should encode time.Duration variable to string with unit (e.g.: 100000000 -> "100ms") when print the the default config with containerd config default.

This pr fixes the bug.

Signed-off-by: Yanqiang Miao miao.yanqiang@zte.com.cn

[dnephin]

Why was this change necessary? Can't you just add MarshalText ?

[miaoyq]

Why was this change necessary?

It can avoid type conversion like time.Duration(cfg.ScheduleDelay).

Can't you just add MarshalText ?

UnmarshalText is not added by me.
Isn't it used when loading config file? I will verify it.

[miaoyq]

@dnephin We need UnmarshalText when loading config file, otherwise containerd service can not start with the error log:

containerd: toml: type mismatch for scheduler.duration: expected table but found string

But I modify UnmarshalText like:

func (d duration) UnmarshalText(_ []byte) error {
	return nil
}

Still works well, don't know why! 😅

[dnephin]

return nil is probably ignoring the problem, it suspect it will serialize to nothing.

My comment wasn't about UnarmshalText. I think it was correct and doesn't need to change.

I was suggesting it would be better to leave the type as type duration time.Duration and remove the other changes from this PR. I don't think the type conversion is a problem. The only thing that needs to change is adding MarshalText

[miaoyq]

@dnephin Thanks for review, have address your comment.

[dnephin]

Thanks. A unit test that show the the roundtrip of values (Marshal, then Unmarshal duration) would be great, especially the value that you found was a problem before.

[stevvooe]

LGTM

@dmcgowan PTAL

[dmcgowan]

LGTM