model: Remove json-iterator usage (again)

This seemingly undoes #440, but all the json-iterator usage was
actually pulled up into client_golang in
prometheus/client_golang#1225 . Detailed
explanation there. In short, we would like to keep heavy dependencies
like json-iterator out of prometheus/common/model since many importers
of this package aren't even interested in the JSON marshaling.

Signed-off-by: beorn7 <beorn@grafana.com>

go.mod

@@ -6,7 +6,6 @@ require (
 	github.com/alecthomas/kingpin/v2 v2.3.1
 	github.com/go-kit/log v0.2.1
 	github.com/golang/protobuf v1.5.2
-	github.com/json-iterator/go v1.1.12
 	github.com/julienschmidt/httprouter v1.3.0
 	github.com/matttproud/golang_protobuf_extensions v1.0.4
 	github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f
@@ -23,8 +22,6 @@ require (
 	github.com/cespare/xxhash/v2 v2.1.2 // indirect
 	github.com/go-logfmt/logfmt v0.5.1 // indirect
 	github.com/jpillora/backoff v1.0.0 // indirect
-	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
-	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/prometheus/procfs v0.8.0 // indirect
 	github.com/stretchr/testify v1.8.0 // indirect
 	github.com/xhit/go-str2duration v1.2.0 // indirect

go.sum

@@ -22,11 +22,8 @@ github.com/golang/protobuf v1.5.2 h1:ROPKBNFfQgOUMifHyP+KYbvpjbdoFNs+aK7DXlji0Tw
 github.com/golang/protobuf v1.5.2/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
-github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/jpillora/backoff v1.0.0 h1:uvFg412JmmHBHw7iwprIxkPMI+sGQ4kzOWsMeHnm2EA=
 github.com/jpillora/backoff v1.0.0/go.mod h1:J/6gKK9jxlEcS3zixgDgUAsiuZ7yrSoa/FX5e0EB2j4=
-github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
-github.com/json-iterator/go v1.1.12/go.mod h1:e30LSqwooZae/UwlEbR2852Gd8hjQvJoHmT4TnhNGBo=
 github.com/julienschmidt/httprouter v1.3.0 h1:U0609e9tgbseu3rBINet9P48AI/D3oJs4dN7jwJOQ1U=
 github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
 github.com/kr/pretty v0.2.1 h1:Fmg33tUaq4/8ym9TJN1x7sLJnHVwhP33CNkpYV/7rwI=
@@ -36,11 +33,6 @@ github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/matttproud/golang_protobuf_extensions v1.0.4 h1:mmDVorXM7PCGKw94cs5zkfA9PSy5pEvNWRP0ET0TIVo=
 github.com/matttproud/golang_protobuf_extensions v1.0.4/go.mod h1:BSXmuO+STAnVfrANrmjBb36TMTDstsz7MSK+HVaYKv4=
-github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
-github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd h1:TRLaZ9cD/w8PVh93nsPXa1VrQ6jlwL5oN8l14QlcNfg=
-github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
-github.com/modern-go/reflect2 v1.0.2 h1:xBagoLtFs94CBntxluKeaWgTMpvLxC4ur3nMaC9Gz0M=
-github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjYzDa0/r8luk=
 github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f h1:KUppIJq7/+SVif2QVs3tOP0zanoHgBEVAwHxUSIzRqU=
 github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
@@ -54,7 +46,6 @@ github.com/prometheus/procfs v0.8.0/go.mod h1:z7EfXMXOkbkqb9IINtpCn86r/to3BnA0ua
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
-github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=

model/value_float.go

@@ -18,15 +18,8 @@ import (
 	"fmt"
 	"math"
 	"strconv"
-	"unsafe"
-
-	jsoniter "github.com/json-iterator/go"
 )
 
-func init() {
-	jsoniter.RegisterTypeEncoderFunc("model.SamplePair", marshalSamplePairJSON, marshalJSONIsEmpty)
-}
-
 var (
 	// ZeroSamplePair is the pseudo zero-value of SamplePair used to signal a
 	// non-existing sample pair. It is a SamplePair with timestamp Earliest and
@@ -78,18 +71,16 @@ type SamplePair struct {
 	Value     SampleValue
 }
 
-// marshalSamplePairJSON writes `[ts, "val"]`.
-func marshalSamplePairJSON(ptr unsafe.Pointer, stream *jsoniter.Stream) {
-	p := *((*SamplePair)(ptr))
-	stream.WriteArrayStart()
-	MarshalTimestamp(int64(p.Timestamp), stream)
-	stream.WriteMore()
-	MarshalValue(float64(p.Value), stream)
-	stream.WriteArrayEnd()
-}
-
 func (s SamplePair) MarshalJSON() ([]byte, error) {
-	return jsoniter.ConfigCompatibleWithStandardLibrary.Marshal(s)
+	t, err := json.Marshal(s.Timestamp)
+	if err != nil {
+		return nil, err
+	}
+	v, err := json.Marshal(s.Value)
+	if err != nil {
+		return nil, err
+	}
+	return []byte(fmt.Sprintf("[%s,%s]", t, v)), nil
 }
 
 // UnmarshalJSON implements json.Unmarshaler.

model/value_histogram.go

@@ -18,16 +18,8 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
-	"unsafe"
-
-	jsoniter "github.com/json-iterator/go"
 )
 
-func init() {
-	jsoniter.RegisterTypeEncoderFunc("model.HistogramBucket", marshalHistogramBucketJSON, marshalJSONIsEmpty)
-	jsoniter.RegisterTypeEncoderFunc("model.SampleHistogramPair", marshalSampleHistogramPairJSON, marshalJSONIsEmpty)
-}
-
 type FloatString float64
 
 func (v FloatString) String() string {
@@ -57,10 +49,24 @@ type HistogramBucket struct {
 	Count      FloatString
 }
 
-// marshalHistogramBucketJSON writes fmt.Sprintf("[%s,%s,%s,%s]", b.Boundaries, b.Lower, b.Upper, b.Count).
-func marshalHistogramBucketJSON(ptr unsafe.Pointer, stream *jsoniter.Stream) {
-	b := *((*HistogramBucket)(ptr))
-	MarshalHistogramBucket(b, stream)
+func (s HistogramBucket) MarshalJSON() ([]byte, error) {
+	b, err := json.Marshal(s.Boundaries)
+	if err != nil {
+		return nil, err
+	}
+	l, err := json.Marshal(s.Lower)
+	if err != nil {
+		return nil, err
+	}
+	u, err := json.Marshal(s.Upper)
+	if err != nil {
+		return nil, err
+	}
+	c, err := json.Marshal(s.Count)
+	if err != nil {
+		return nil, err
+	}
+	return []byte(fmt.Sprintf("[%s,%s,%s,%s]", b, l, u, c)), nil
 }
 
 func (s *HistogramBucket) UnmarshalJSON(buf []byte) error {
@@ -133,21 +139,19 @@ type SampleHistogramPair struct {
 	Histogram *SampleHistogram
 }
 
-// marshalSampleHistogramPairJSON writes `[ts, "val"]`.
-func marshalSampleHistogramPairJSON(ptr unsafe.Pointer, stream *jsoniter.Stream) {
-	p := *((*SampleHistogramPair)(ptr))
-	stream.WriteArrayStart()
-	MarshalTimestamp(int64(p.Timestamp), stream)
-	stream.WriteMore()
-	MarshalHistogram(*p.Histogram, stream)
-	stream.WriteArrayEnd()
-}
-
 func (s SampleHistogramPair) MarshalJSON() ([]byte, error) {
 	if s.Histogram == nil {
 		return nil, fmt.Errorf("histogram is nil")
 	}
-	return jsoniter.ConfigCompatibleWithStandardLibrary.Marshal(s)
+	t, err := json.Marshal(s.Timestamp)
+	if err != nil {
+		return nil, err
+	}
+	v, err := json.Marshal(s.Histogram)
+	if err != nil {
+		return nil, err
+	}
+	return []byte(fmt.Sprintf("[%s,%s]", t, v)), nil
 }
 
 func (s *SampleHistogramPair) UnmarshalJSON(buf []byte) error {