138 lines
3.8 KiB
Go
138 lines
3.8 KiB
Go
// Copyright 2022 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package jsonutil
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import (
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"math"
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"strconv"
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jsoniter "github.com/json-iterator/go"
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"github.com/prometheus/prometheus/model/histogram"
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)
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// MarshalTimestamp marshals a point timestamp using the passed jsoniter stream.
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func MarshalTimestamp(t int64, stream *jsoniter.Stream) {
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// Write out the timestamp as a float divided by 1000.
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// This is ~3x faster than converting to a float.
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if t < 0 {
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stream.WriteRaw(`-`)
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t = -t
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}
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stream.WriteInt64(t / 1000)
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fraction := t % 1000
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if fraction != 0 {
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stream.WriteRaw(`.`)
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if fraction < 100 {
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stream.WriteRaw(`0`)
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}
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if fraction < 10 {
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stream.WriteRaw(`0`)
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}
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stream.WriteInt64(fraction)
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}
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}
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// MarshalFloat marshals a float value using the passed jsoniter stream.
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func MarshalFloat(f float64, stream *jsoniter.Stream) {
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stream.WriteRaw(`"`)
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// Taken from https://github.com/json-iterator/go/blob/master/stream_float.go#L71 as a workaround
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// to https://github.com/json-iterator/go/issues/365 (jsoniter, to follow json standard, doesn't allow inf/nan).
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buf := stream.Buffer()
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abs := math.Abs(f)
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fmt := byte('f')
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// Note: Must use float32 comparisons for underlying float32 value to get precise cutoffs right.
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if abs != 0 {
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if abs < 1e-6 || abs >= 1e21 {
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fmt = 'e'
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}
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}
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buf = strconv.AppendFloat(buf, f, fmt, -1, 64)
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stream.SetBuffer(buf)
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stream.WriteRaw(`"`)
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}
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// MarshalHistogram marshals a histogram value using the passed jsoniter stream.
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// It writes something like:
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//
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// {
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// "count": "42",
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// "sum": "34593.34",
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// "buckets": [
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// [ 3, "-0.25", "0.25", "3"],
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// [ 0, "0.25", "0.5", "12"],
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// [ 0, "0.5", "1", "21"],
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// [ 0, "2", "4", "6"]
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// ]
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// }
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//
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// The 1st element in each bucket array determines if the boundaries are
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// inclusive (AKA closed) or exclusive (AKA open):
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//
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// 0: lower exclusive, upper inclusive
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// 1: lower inclusive, upper exclusive
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// 2: both exclusive
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// 3: both inclusive
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//
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// The 2nd and 3rd elements are the lower and upper boundary. The 4th element is
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// the bucket count.
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func MarshalHistogram(h *histogram.FloatHistogram, stream *jsoniter.Stream) {
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stream.WriteObjectStart()
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stream.WriteObjectField(`count`)
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MarshalFloat(h.Count, stream)
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stream.WriteMore()
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stream.WriteObjectField(`sum`)
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MarshalFloat(h.Sum, stream)
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bucketFound := false
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it := h.AllBucketIterator()
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for it.Next() {
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bucket := it.At()
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if bucket.Count == 0 {
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continue // No need to expose empty buckets in JSON.
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}
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stream.WriteMore()
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if !bucketFound {
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stream.WriteObjectField(`buckets`)
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stream.WriteArrayStart()
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}
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bucketFound = true
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boundaries := 2 // Exclusive on both sides AKA open interval.
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if bucket.LowerInclusive {
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if bucket.UpperInclusive {
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boundaries = 3 // Inclusive on both sides AKA closed interval.
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} else {
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boundaries = 1 // Inclusive only on lower end AKA right open.
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}
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} else {
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if bucket.UpperInclusive {
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boundaries = 0 // Inclusive only on upper end AKA left open.
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}
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}
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stream.WriteArrayStart()
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stream.WriteInt(boundaries)
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stream.WriteMore()
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MarshalFloat(bucket.Lower, stream)
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stream.WriteMore()
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MarshalFloat(bucket.Upper, stream)
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stream.WriteMore()
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MarshalFloat(bucket.Count, stream)
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stream.WriteArrayEnd()
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}
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if bucketFound {
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stream.WriteArrayEnd()
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}
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stream.WriteObjectEnd()
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}
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