api: export point marshaling functions (#11323)

Export `marshalTimestamp` and `marshalValue` functions by moving them under their own util package.

Signed-off-by: Miguel Ángel Ortuño <ortuman@gmail.com>

util/jsonutil/marshal.go

@@ -0,0 +1,62 @@
+// Copyright 2022 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package jsonutil
+
+import (
+	"math"
+	"strconv"
+
+	jsoniter "github.com/json-iterator/go"
+)
+
+// MarshalTimestamp marshals a point timestamp using the passed jsoniter stream.
+func MarshalTimestamp(t int64, stream *jsoniter.Stream) {
+	// Write out the timestamp as a float divided by 1000.
+	// This is ~3x faster than converting to a float.
+	if t < 0 {
+		stream.WriteRaw(`-`)
+		t = -t
+	}
+	stream.WriteInt64(t / 1000)
+	fraction := t % 1000
+	if fraction != 0 {
+		stream.WriteRaw(`.`)
+		if fraction < 100 {
+			stream.WriteRaw(`0`)
+		}
+		if fraction < 10 {
+			stream.WriteRaw(`0`)
+		}
+		stream.WriteInt64(fraction)
+	}
+}
+
+// MarshalValue marshals a point value using the passed jsoniter stream.
+func MarshalValue(v float64, stream *jsoniter.Stream) {
+	stream.WriteRaw(`"`)
+	// Taken from https://github.com/json-iterator/go/blob/master/stream_float.go#L71 as a workaround
+	// to https://github.com/json-iterator/go/issues/365 (jsoniter, to follow json standard, doesn't allow inf/nan).
+	buf := stream.Buffer()
+	abs := math.Abs(v)
+	fmt := byte('f')
+	// Note: Must use float32 comparisons for underlying float32 value to get precise cutoffs right.
+	if abs != 0 {
+		if abs < 1e-6 || abs >= 1e21 {
+			fmt = 'e'
+		}
+	}
+	buf = strconv.AppendFloat(buf, v, fmt, -1, 64)
+	stream.SetBuffer(buf)
+	stream.WriteRaw(`"`)
+}

web/api/v1/api.go

@@ -52,6 +52,7 @@ import (
 	"github.com/prometheus/prometheus/tsdb"
 	"github.com/prometheus/prometheus/tsdb/index"
 	"github.com/prometheus/prometheus/util/httputil"
+	"github.com/prometheus/prometheus/util/jsonutil"
 	"github.com/prometheus/prometheus/util/stats"
 )
 
@@ -1659,9 +1660,9 @@ OUTER:
 func marshalPointJSON(ptr unsafe.Pointer, stream *jsoniter.Stream) {
 	p := *((*promql.Point)(ptr))
 	stream.WriteArrayStart()
-	marshalTimestamp(p.T, stream)
+	jsonutil.MarshalTimestamp(p.T, stream)
 	stream.WriteMore()
-	marshalValue(p.V, stream)
+	jsonutil.MarshalValue(p.V, stream)
 	stream.WriteArrayEnd()
 }
 
@@ -1692,13 +1693,12 @@ func marshalExemplarJSON(ptr unsafe.Pointer, stream *jsoniter.Stream) {
 	// "value" key.
 	stream.WriteMore()
 	stream.WriteObjectField(`value`)
-	marshalValue(p.Value, stream)
+	jsonutil.MarshalValue(p.Value, stream)
 
 	// "timestamp" key.
 	stream.WriteMore()
 	stream.WriteObjectField(`timestamp`)
-	marshalTimestamp(p.Ts, stream)
-	// marshalTimestamp(p.Ts, stream)
+	jsonutil.MarshalTimestamp(p.Ts, stream)
 
 	stream.WriteObjectEnd()
 }
@@ -1706,42 +1706,3 @@ func marshalExemplarJSON(ptr unsafe.Pointer, stream *jsoniter.Stream) {
 func marshalExemplarJSONEmpty(ptr unsafe.Pointer) bool {
 	return false
 }
-
-func marshalTimestamp(t int64, stream *jsoniter.Stream) {
-	// Write out the timestamp as a float divided by 1000.
-	// This is ~3x faster than converting to a float.
-	if t < 0 {
-		stream.WriteRaw(`-`)
-		t = -t
-	}
-	stream.WriteInt64(t / 1000)
-	fraction := t % 1000
-	if fraction != 0 {
-		stream.WriteRaw(`.`)
-		if fraction < 100 {
-			stream.WriteRaw(`0`)
-		}
-		if fraction < 10 {
-			stream.WriteRaw(`0`)
-		}
-		stream.WriteInt64(fraction)
-	}
-}
-
-func marshalValue(v float64, stream *jsoniter.Stream) {
-	stream.WriteRaw(`"`)
-	// Taken from https://github.com/json-iterator/go/blob/master/stream_float.go#L71 as a workaround
-	// to https://github.com/json-iterator/go/issues/365 (jsoniter, to follow json standard, doesn't allow inf/nan).
-	buf := stream.Buffer()
-	abs := math.Abs(v)
-	fmt := byte('f')
-	// Note: Must use float32 comparisons for underlying float32 value to get precise cutoffs right.
-	if abs != 0 {
-		if abs < 1e-6 || abs >= 1e21 {
-			fmt = 'e'
-		}
-	}
-	buf = strconv.AppendFloat(buf, v, fmt, -1, 64)
-	stream.SetBuffer(buf)
-	stream.WriteRaw(`"`)
-}