63 lines
1.8 KiB
Go
63 lines
1.8 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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)
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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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// MarshalValue marshals a point value using the passed jsoniter stream.
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func MarshalValue(v 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(v)
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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, v, fmt, -1, 64)
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stream.SetBuffer(buf)
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stream.WriteRaw(`"`)
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}
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