MeterValue with "d" suffix not parsed as Duration for timer

[bespaltovyj]

Spring Boot Version 2.4.8

If you specify a value with the suffix d for the timer when setting slo, then it is parsed as a number, not a duration.

Example:

management:
  metrics:
    distribution:
      slo:
        <YOUR_TIMER_NAME>: 1d, 2d, 3d

The values of the baskets will be 1, 2 ,3, but required 86400s, 172800s, 259200s.

test example

To work around this problem, I specify the duration in hours.

[polarbear567]

Hi @bespaltovyj ,
In this configuration, if you want to use seconds as the unit, in your example, I think you should use s, as follows:

management:
  metrics:
    distribution:
      slo:
        <YOUR_TIMER_NAME>: 86400s, 172800s, 259200s

But this is an interesting problem. The root cause of this problem is that we will eventually convert the value to a double type, but for the value like 1d, the Double.parseDouble(String s) method will directly convert it to 1.0.
@wilkinsona @snicoll I don't know what is the ideal treatment for string values like "1d" in design, whether it is regarded as a double value or a day?

[wilkinsona]

The documentation for the slo map states the following:

Values can be specified as a long or as a Duration value (for timer meters, defaulting to ms if no unit specified)

I think we should be aiming to match the implementation to that documentation.

[wilkinsona]

It looks like this worked in 2.2 but the behaviour changed due to #20837. Contrary to what I said above, it looks like the documentation for the slo map should have been updated to reflect the switch from long to double. The question now is how to handle a value that's both a valid double and a valid duration such as 1d.

[wilkinsona]

The question now is how to handle a value that's both a valid double and a valid duration such as 1d.

If we assume that 1d should be treated as a duration of one day, flipping the order so we trying to parse as a Duration and then fall back to a double seems to work.