diff options
Diffstat (limited to 'src/runtime/metrics/histogram.go')
| -rw-r--r-- | src/runtime/metrics/histogram.go | 29 |
1 files changed, 16 insertions, 13 deletions
diff --git a/src/runtime/metrics/histogram.go b/src/runtime/metrics/histogram.go index e1364e1e26..956422bf84 100644 --- a/src/runtime/metrics/histogram.go +++ b/src/runtime/metrics/histogram.go @@ -6,25 +6,28 @@ package metrics // Float64Histogram represents a distribution of float64 values. type Float64Histogram struct { - // Counts contains the weights for each histogram bucket. The length of - // Counts is equal to the length of Buckets (in the metric description) - // plus one to account for the implicit minimum bucket. + // Counts contains the weights for each histogram bucket. // - // Given N buckets, the following is the mathematical relationship between - // Counts and Buckets. - // count[0] is the weight of the range (-inf, bucket[0]) - // count[n] is the weight of the range [bucket[n], bucket[n+1]), for 0 < n < N-1 - // count[N-1] is the weight of the range [bucket[N-1], inf) + // Given N buckets, Count[n] is the weight of the range + // [bucket[n], bucket[n+1]), for 0 <= n < N. Counts []uint64 - // Buckets contains the boundaries between histogram buckets, in increasing order. + // Buckets contains the boundaries of the histogram buckets, in increasing order. // - // Because this slice contains boundaries, there are len(Buckets)+1 counts: - // a count for all values less than the first boundary, a count covering each - // [slice[i], slice[i+1]) interval, and a count for all values greater than or - // equal to the last boundary. + // Buckets[0] is the inclusive lower bound of the minimum bucket while + // Buckets[len(Buckets)-1] is the exclusive upper bound of the maximum bucket. + // Hence, there are len(Buckets)-1 counts. Furthermore, len(Buckets) != 1, always, + // since at least two boundaries are required to describe one bucket (and 0 + // boundaries are used to describe 0 buckets). + // + // Buckets[0] is permitted to have value -Inf and Buckets[len(Buckets)-1] is + // permitted to have value Inf. // // For a given metric name, the value of Buckets is guaranteed not to change // between calls until program exit. + // + // This slice value is permitted to alias with other Float64Histograms' Buckets + // fields, so the values within should only ever be read. If they need to be + // modified, the user must make a copy. Buckets []float64 } |