Review and adjust the default `DistributionStatisticConfig`

[trustin]

Currently, Armeria uses the default DistributionStatisticConfig of:

DistributionStatisticConfig
  .builder()
  .percentilesHistogram(false)
  .sla()
  .percentiles(new double[] { 0, 0.5, 0.75, 0.9, 0.95, 0.98, 0.99, 0.999, 1.0 })
  .percentilePrecision(2)
  .minimumExpectedValue(1L)
  .maximumExpectedValue(Long.MAX_VALUE)
  .expiry(Duration.ofMinutes(3))
  .bufferLength(3)
  .build();

When we define the above defaults, our intention was to rotate the buffer every minute, as explained in the comments:

    /**
     * Export the percentile values only by default. We specify all properties so that we get consistent values
     * even if Micrometer changes its defaults. Most notably, we changed {@code percentilePrecision},
     * {@code expiry} and {@code bufferLength} due to the following reasons:
     * <ul>
     *   <li>The default {@code percentilePrecision} of 1 is way too inaccurate.</li>
     *   <li>Histogram buckets should be rotated every minute rather than every some-arbitrary-seconds
     *       because that fits better to human's mental model of time. Micrometer's 2 minutes / 3 buffers
     *       (i.e. rotate every 40 seconds) does not make much sense.</li>
     * </ul>
     */

However, according to TimeWindowMax.rotate(): https://github.com/micrometer-metrics/micrometer/blob/v1.7.1/micrometer-core/src/main/java/io/micrometer/core/instrument/distribution/TimeWindowMax.java#L118-L145

it seems to me that the buffers are rotated every 3 minutes.

Action item: Double check if the buffers are rotated every minute with the current defaults. Change the defaults if we were mistaken.

[trustin]

@anuraaga @mauhiz Do you remember anything about this when we chose the above defaults?

[mauhiz]

Was I involved? I always thought this logic to be weird :D

[mauhiz]

By the way: I think the current trend is to define a MeterFilter to configure most of these properties, not to set them directly on DistributionConfig. https://micrometer.io/docs/concepts#_configuring_distribution_statistics

[imasahiro]

ref: https://github.com/line/armeria/pull/1226 (let me revisit here next monday)