perf: use parse instead of getMany for gjson

[rahulguptajss]

BenchStat

benchstat old.txt new.txt                                                                                              
goos: darwin
goarch: amd64
pkg: github.com/netapp/harvest/v2/cmd/tools/rest
cpu: Intel(R) Core(TM) i7-1068NG7 CPU @ 2.30GHz
      │   old.txt   │              new.txt               │
      │   sec/op    │   sec/op     vs base               │
Run-8   175.5m ± 3%   167.8m ± 1%  -4.39% (p=0.000 n=20)

      │    old.txt    │               new.txt                │
      │     B/op      │     B/op      vs base                │
Run-8   29.432Mi ± 0%   4.494Mi ± 0%  -84.73% (p=0.000 n=20)

      │  old.txt   │              new.txt               │
      │ allocs/op  │ allocs/op   vs base                │
Run-8   23.00 ± 0%   20.00 ± 0%  -13.04% (p=0.000 n=20)

GetManyBytes

goos: darwin
goarch: amd64
pkg: github.com/netapp/harvest/v2/cmd/tools/rest
cpu: Intel(R) Core(TM) i7-1068NG7 CPU @ 2.30GHz
BenchmarkRun-8   	       6	 176583157 ns/op	30864000 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 171905008 ns/op	30863104 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 173131458 ns/op	30861786 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 172861186 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 191586987 ns/op	30863104 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 208865388 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 182311277 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 184147214 ns/op	30861744 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 174858837 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 172048299 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 175390261 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 174621808 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 175406557 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 182451984 ns/op	30861770 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 171076953 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 175685866 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 176748725 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 177837733 ns/op	30861754 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 173864807 ns/op	30861738 B/op	      23 allocs/op
BenchmarkRun-8   	       6	 181394717 ns/op	30861738 B/op	      23 allocs/op
PASS
ok  	github.com/netapp/harvest/v2/cmd/tools/rest	66.796s

ParseBytes

goos: darwin
goarch: amd64
pkg: github.com/netapp/harvest/v2/cmd/tools/rest
cpu: Intel(R) Core(TM) i7-1068NG7 CPU @ 2.30GHz
BenchmarkRun-8   	       7	 166125964 ns/op	 4714582 B/op	      20 allocs/op
BenchmarkRun-8   	       6	 168723358 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 166443073 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 168285388 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 168824665 ns/op	 4713794 B/op	      20 allocs/op
BenchmarkRun-8   	       6	 167641136 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       6	 168703432 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       6	 166981145 ns/op	 4717426 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 168052484 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       6	 177139801 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 171096416 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 168462390 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 167633231 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 166960088 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       6	 167239540 ns/op	 4712629 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 167137994 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       6	 170434566 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 164541698 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       6	 177470561 ns/op	 4712624 B/op	      20 allocs/op
BenchmarkRun-8   	       7	 167038610 ns/op	 4712624 B/op	      20 allocs/op
PASS
ok  	github.com/netapp/harvest/v2/cmd/tools/rest	70.290s

Benchmark Code

package rest

import (
	"github.com/tidwall/gjson"
	"github.com/tidwall/sjson"
	"io/ioutil"
	"net/http"
	"testing"
)

var path = "https://raw.githubusercontent.com/json-iterator/test-data/master/large-file.json"

func BenchmarkParse(b *testing.B) {
	_, newJson := initFile()

	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		o := gjson.Parse(newJson)
		records := o.Get("records").Array()
		numRecords := o.Get("num_records").Int()
		href := o.Get("_links.self.href").String()

		_ = records
		_ = numRecords
		_ = href
	}
}

func BenchmarkGet(b *testing.B) {

	bytes, _ := initFile()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		o := gjson.GetManyBytes(bytes, "records", "num_records", "_links.next.href")
		records := o[0].Array()
		numRecords := o[1].Int()
		links := o[2].String()
		_ = records
		_ = numRecords
		_ = links
	}

}

func initFile() ([]byte, string) {
	resp, err := http.Get(path)
	if err != nil {
		panic(err)
	}
	defer resp.Body.Close()

	bytes, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		panic(err)
	}

	json := string(bytes)

	newJson, err := sjson.SetRaw(`{}`, "records", json)
	if err != nil {
		panic(err)
	}

	newJson, err = sjson.Set(newJson, "num_records", 197)
	if err != nil {
		panic(err)
	}

	newJson, err = sjson.Set(newJson, "_links.self.href", "/api/storage/volumes?fields=*")
	if err != nil {
		panic(err)
	}

	bytes = []byte(newJson)

	return bytes, newJson
}