results: Faster JSON encoding and decoding (#506)

* Add .idea to .gitignore

* results: Faster JSON encoding and decoding

This commit improves the performance of JSON encoding and decoding of
`Results`. Additionally, it fixes a regression introduced in #474 that
didn't produce valid JSON for HTTP headers. A test is added that
validates the JSON encoding matches the one produced by the
`encoding/json`.

```
name                            old time/op    new time/op    delta
ResultEncodings/json-encode-16     690ns ±12%     297ns ± 0%   -56.94%
(p=0.000 n=9+9)
ResultEncodings/json-decode-16    1.05µs ± 1%    0.03µs ± 1%   -97.47%
(p=0.000 n=10+8)

name                            old alloc/op   new alloc/op   delta
ResultEncodings/json-encode-16      804B ±87%        0B       -100.00%
(p=0.000 n=9+10)
ResultEncodings/json-decode-16      310B ± 0%        0B       -100.00%
(p=0.000 n=10+10)

name                            old allocs/op  new allocs/op  delta
ResultEncodings/json-encode-16      4.00 ± 0%      0.00       -100.00%
(p=0.000 n=10+10)
ResultEncodings/json-decode-16      4.00 ± 0%      0.00       -100.00%
(p=0.000 n=10+10)
```

.gitignore

@@ -32,3 +32,4 @@ vendor
 *.lz
 
 .DS_Store
+.idea

go.mod

@@ -23,5 +23,6 @@ require (
 	github.com/miekg/dns v1.1.17
 	github.com/streadway/quantile v0.0.0-20150917103942-b0c588724d25
 	github.com/tsenart/go-tsz v0.0.0-20180814232043-cdeb9e1e981e
+	github.com/valyala/fastjson v1.5.0
 	golang.org/x/net v0.0.0-20190827160401-ba9fcec4b297
 )

go.sum

@@ -38,6 +38,8 @@ github.com/streadway/quantile v0.0.0-20150917103942-b0c588724d25 h1:7z3LSn867ex6
 github.com/streadway/quantile v0.0.0-20150917103942-b0c588724d25/go.mod h1:lbP8tGiBjZ5YWIc2fzuRpTaz0b/53vT6PEs3QuAWzuU=
 github.com/tsenart/go-tsz v0.0.0-20180814232043-cdeb9e1e981e h1:bB5SXzQmSUsJCmjPDN9fKYx3SSDER5diSjlN6TefTCc=
 github.com/tsenart/go-tsz v0.0.0-20180814232043-cdeb9e1e981e/go.mod h1:SWZznP1z5Ki7hDT2ioqiFKEse8K9tU2OUvaRI0NeGQo=
+github.com/valyala/fastjson v1.5.0 h1:DGrb4wEYso2HdGLyLmNoyNCQnCWfjd8yhghPv5/5YQg=
+github.com/valyala/fastjson v1.5.0/go.mod h1:CLCAqky6SMuOcxStkYQvblddUtoRxhYMGLrsQns1aXY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190829043050-9756ffdc2472 h1:Gv7RPwsi3eZ2Fgewe3CBsuOebPwO27PoXzRpJPsvSSM=
 golang.org/x/crypto v0.0.0-20190829043050-9756ffdc2472/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=

lib/results.go

@@ -13,9 +13,6 @@ import (
 	"strconv"
 	"strings"
 	"time"
-
-	"github.com/mailru/easyjson/jlexer"
-	jwriter "github.com/mailru/easyjson/jwriter"
 )
 
 func init() {
@@ -267,34 +264,3 @@ func NewCSVDecoder(r io.Reader) Decoder {
 	}
 }
 
-//go:generate easyjson -no_std_marshalers -output_filename results_easyjson.go results.go
-//easyjson:json
-type jsonResult Result
-
-// NewJSONEncoder returns an Encoder that dumps the given *Results as a JSON
-// object.
-func NewJSONEncoder(w io.Writer) Encoder {
-	var jw jwriter.Writer
-	return func(r *Result) error {
-		(*jsonResult)(r).MarshalEasyJSON(&jw)
-		if jw.Error != nil {
-			return jw.Error
-		}
-		jw.RawByte('\n')
-		_, err := jw.DumpTo(w)
-		return err
-	}
-}
-
-// NewJSONDecoder returns a Decoder that decodes JSON encoded Results.
-func NewJSONDecoder(r io.Reader) Decoder {
-	rd := bufio.NewReader(r)
-	return func(r *Result) (err error) {
-		var jl jlexer.Lexer
-		if jl.Data, err = rd.ReadBytes('\n'); err != nil {
-			return err
-		}
-		(*jsonResult)(r).UnmarshalEasyJSON(&jl)
-		return jl.Error()
-	}
-}