Prometheus: Introduce prometheus backend library (#83952)

* Move files to prometheus-library

* refactor core prometheus to use prometheus-library

* modify client transport options

* mock

* have a type

* import aliases

* rename

* call the right method

* remove unrelated test from the library

* update codeowners

* go work sync

* update go.work.sum

* make swagger-clean && make openapi3-gen

* add promlib to makefile

* remove clilogger

* Export the function

* update unit test

* add prometheus_test.go

* fix mock type

* use mapUtil from grafana-plugin-sdk-go

pkg/promlib/querydata/framing_bench_test.go

@@ -0,0 +1,153 @@
+package querydata_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"math/rand"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/stretchr/testify/require"
+
+	"github.com/grafana/grafana/pkg/promlib/models"
+)
+
+// when memory-profiling this benchmark, these commands are recommended:
+// - go test -benchmem -run=^$ -bench ^BenchmarkExemplarJson$ github.com/grafana/grafana/pkg/promlib/querydata -memprofile memprofile.out -count 6 | tee old.txt
+// - go tool pprof -http=localhost:6061 memprofile.out
+func BenchmarkExemplarJson(b *testing.B) {
+	queryFileName := filepath.Join("../testdata", "exemplar.query.json")
+	query, err := loadStoredQuery(queryFileName)
+	require.NoError(b, err)
+
+	responseFileName := filepath.Join("../testdata", "exemplar.result.json")
+
+	// nolint:gosec
+	// We can ignore the gosec G304 warning since this is a test file
+	responseBytes, err := os.ReadFile(responseFileName)
+	require.NoError(b, err)
+
+	tCtx, err := setup()
+	require.NoError(b, err)
+	b.ResetTimer()
+	for n := 0; n < b.N; n++ {
+		res := http.Response{
+			StatusCode: 200,
+			Body:       io.NopCloser(bytes.NewReader(responseBytes)),
+		}
+		tCtx.httpProvider.setResponse(&res)
+		resp, err := tCtx.queryData.Execute(context.Background(), query)
+		require.NoError(b, err)
+		for _, r := range resp.Responses {
+			require.NoError(b, r.Error)
+		}
+	}
+}
+
+var resp *backend.QueryDataResponse
+
+// when memory-profiling this benchmark, these commands are recommended:
+// - go test -benchmem -run=^$ -bench ^BenchmarkRangeJson$ github.com/grafana/grafana/pkg/promlib/querydata -memprofile memprofile.out -count 6 | tee old.txt
+// - go tool pprof -http=localhost:6061 memprofile.out
+// - benchstat old.txt new.txt
+func BenchmarkRangeJson(b *testing.B) {
+	var (
+		r   *backend.QueryDataResponse
+		err error
+	)
+	body, q := createJsonTestData(1642000000, 1, 300, 400)
+	tCtx, err := setup()
+	require.NoError(b, err)
+
+	b.ResetTimer()
+
+	for n := 0; n < b.N; n++ {
+		res := http.Response{
+			StatusCode: 200,
+			Body:       io.NopCloser(bytes.NewReader(body)),
+		}
+		tCtx.httpProvider.setResponse(&res)
+		r, err = tCtx.queryData.Execute(context.Background(), q)
+		require.NoError(b, err)
+	}
+
+	resp = r
+}
+
+const nanRate = 0.002
+
+// we build the JSON file from strings,
+// it was easier to write it this way.
+func makeJsonTestMetric(index int) string {
+	return fmt.Sprintf(`{"server":"main","category":"maintenance","case":"%v"}`, index)
+}
+
+// return a value between -100 and +100, sometimes NaN, in string
+func makeJsonTestValue(r *rand.Rand) string {
+	if r.Float64() < nanRate {
+		return "NaN"
+	} else {
+		return fmt.Sprintf("%f", (r.Float64()*200)-100)
+	}
+}
+
+// create one time-series
+func makeJsonTestSeries(start int64, step int64, timestampCount int, r *rand.Rand, seriesIndex int) string {
+	var values []string
+	for i := 0; i < timestampCount; i++ {
+		// create out of order timestamps to test sorting
+		if seriesIndex == 0 && i%2 == 0 {
+			continue
+		}
+		value := fmt.Sprintf(`[%d,"%v"]`, start+(int64(i)*step), makeJsonTestValue(r))
+		values = append(values, value)
+	}
+	return fmt.Sprintf(`{"metric":%v,"values":[%v]}`, makeJsonTestMetric(seriesIndex), strings.Join(values, ","))
+}
+
+func createJsonTestData(start int64, step int64, timestampCount int, seriesCount int) ([]byte, *backend.QueryDataRequest) {
+	// we use random numbers as values, but they have to be the same numbers
+	// every time we call this, so we create a random source.
+	r := rand.New(rand.NewSource(42))
+	var allSeries []string
+	for i := 0; i < seriesCount; i++ {
+		allSeries = append(allSeries, makeJsonTestSeries(start, step, timestampCount, r, i))
+	}
+	bytes := []byte(fmt.Sprintf(`{"status":"success","data":{"resultType":"matrix","result":[%v]}}`, strings.Join(allSeries, ",")))
+
+	qm := models.QueryModel{
+		PrometheusQueryProperties: models.PrometheusQueryProperties{
+			Range: true,
+			Expr:  "test",
+		},
+	}
+
+	data, err := json.Marshal(&qm)
+	if err != nil {
+		panic(err)
+	}
+
+	res := backend.QueryDataRequest{
+		Queries: []backend.DataQuery{
+			{
+				RefID: "A",
+				TimeRange: backend.TimeRange{
+					From: time.Unix(start, 0),
+					To:   time.Unix(start+((int64(timestampCount)-1)*step), 0),
+				},
+				Interval: time.Second * time.Duration(step),
+				JSON:     data,
+			},
+		},
+	}
+
+	return bytes, &res
+}