dashboard/app: read lines coverage from spanner

We currently merge bigquery data for every line coverage request.
Let's read cached lines coverage data from spanner instead.
It allows to get only 1 file version from git and skip the data merge step.

1 files changed, 59 insertions, 0 deletions

diff --git a/pkg/coveragedb/spanner.go b/pkg/coveragedb/spanner.go
index 0ff3a3197..54fa2e192 100644
--- a/pkg/coveragedb/spanner.go
+++ b/pkg/coveragedb/spanner.go
@@ -6,6 +6,7 @@ package coveragedb
 import (
 	"context"
 	"fmt"
+	"os"
 	"time"
 
 	"cloud.google.com/go/civil"
@@ -89,6 +90,64 @@ func SaveMergeResult(ctx context.Context, projectID string, covMap map[string]*C
 	return nil
 }
 
+type linesCoverage struct {
+	LinesInstrumented []int64
+	HitCounts         []int64
+}
+
+func linesCoverageStmt(ns, filepath, commit string, timePeriod TimePeriod) spanner.Statement {
+	return spanner.Statement{
+		SQL: `
+select
+	linesinstrumented,
+	hitcounts
+from merge_history
+	join files
+		on merge_history.session = files.session
+where
+	namespace=$1 and dateto=$2 and duration=$3 and filepath=$4 and commit=$5`,
+		Params: map[string]interface{}{
+			"p1": ns,
+			"p2": timePeriod.DateTo,
+			"p3": timePeriod.Days,
+			"p4": filepath,
+			"p5": commit,
+		},
+	}
+}
+
+func ReadLinesHitCount(ctx context.Context, ns, commit, file string, tp TimePeriod,
+) (map[int]int, error) {
+	projectID := os.Getenv("GOOGLE_CLOUD_PROJECT")
+	client, err := NewClient(ctx, projectID)
+	if err != nil {
+		return nil, fmt.Errorf("spanner.NewClient: %w", err)
+	}
+	defer client.Close()
+
+	stmt := linesCoverageStmt(ns, file, commit, tp)
+	iter := client.Single().Query(ctx, stmt)
+	defer iter.Stop()
+
+	row, err := iter.Next()
+	if err == iterator.Done {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, fmt.Errorf("iter.Next: %w", err)
+	}
+	var r linesCoverage
+	if err = row.ToStruct(&r); err != nil {
+		return nil, fmt.Errorf("failed to row.ToStruct() spanner DB: %w", err)
+	}
+
+	res := map[int]int{}
+	for i, instrLine := range r.LinesInstrumented {
+		res[int(instrLine)] = int(r.HitCounts[i])
+	}
+	return res, nil
+}
+
 func historyMutation(session string, template *HistoryRecord, totalRows int64) *spanner.Mutation {
 	historyInsert, err := spanner.InsertOrUpdateStruct("merge_history", &HistoryRecord{
 		Session:   session,