wp

mqe/period_producers.go

@@ -0,0 +1,168 @@
+package mqe
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+)
+
+type periodProducer interface {
+	Next() (time.Time, PeriodBound, PeriodBound, bool, error)
+	Last() (PeriodBound, bool, error)
+}
+
+type PeriodBound struct {
+	Time  int64
+	Value float64
+}
+
+type PeriodProducer struct {
+	metricID          int64
+	parsePeriodLayout string
+	location          *time.Location
+	until             int64
+	corrections       []_f64Correction
+	rows              *sql.Rows
+	tx                *sql.Tx
+}
+
+type PeriodProducerOptions struct {
+	MetricID          int64
+	ParsePeriodLayout string
+	Location          *time.Location
+	Until             int64
+	Corrections       []_f64Correction
+	Rows              *sql.Rows
+	Tx                *sql.Tx
+}
+
+func NewPeriodProducer(opt PeriodProducerOptions) *PeriodProducer {
+	if opt.Location == nil {
+		panic("Location option is required")
+	}
+
+	if opt.MetricID == 0 {
+		panic("MetricID option is required")
+	}
+
+	if opt.ParsePeriodLayout == "" {
+		panic("ParsePeriodLayout option is required")
+	}
+
+	if opt.Until == 0 {
+		panic("Until option is required")
+	}
+
+	if opt.Rows == nil {
+		panic("Rows option is required")
+	}
+
+	if opt.Tx == nil {
+		panic("Tx option is required")
+	}
+
+	s := new(PeriodProducer)
+	s.metricID = opt.MetricID
+	s.parsePeriodLayout = opt.ParsePeriodLayout
+	s.location = opt.Location
+	s.until = opt.Until
+	s.corrections = opt.Corrections
+	s.rows = opt.Rows
+	s.tx = opt.Tx
+	return s
+}
+
+func (s *PeriodProducer) Next() (period time.Time, first PeriodBound, last PeriodBound, found bool, err error) {
+	var frameStr string
+
+	hasNext := s.rows.Next()
+	if hasNext {
+		err = s.rows.Scan(&frameStr, &first.Time, &first.Value, &last.Time, &last.Value)
+		if err != nil {
+			return
+		}
+
+		first.Value = applyCorrectionsToMeasure(s.corrections, first.Time, first.Value)
+		last.Value = applyCorrectionsToMeasure(s.corrections, last.Time, last.Value)
+
+		period, err = time.ParseInLocation(s.parsePeriodLayout, frameStr, s.location)
+		if err != nil {
+			err = fmt.Errorf("time.ParseInLocation: %s; layout=%q; str=%q",
+				err, s.parsePeriodLayout, frameStr)
+			return
+		}
+
+		found = true
+	} else {
+		err = s.rows.Err()
+	}
+	return
+}
+
+func (s *PeriodProducer) Last() (next PeriodBound, found bool, err error) {
+	// Находим следующее показание метрики.
+	err = s.tx.QueryRow(`
+	SELECT tm, value, true
+	FROM f64
+	WHERE metricID=? AND tm > ?
+	ORDER BY tm ASC
+	LIMIT 1`,
+		s.metricID, s.until).Scan(&next.Time, &next.Value, &found)
+
+	if err != nil {
+		if err != sql.ErrNoRows {
+			return
+		}
+		// Нет записей
+		err = nil
+	}
+
+	next.Value = applyCorrectionsToMeasure(s.corrections, next.Time, next.Value)
+	return
+}
+
+// ДЛЯ ТЕСТИРОВАНИЯ
+
+type stubPeriod struct {
+	Period time.Time
+	First  PeriodBound
+	Last   PeriodBound
+}
+
+type StubPeriodProducerOptions struct {
+	Last    *PeriodBound
+	Periods []stubPeriod
+}
+
+func NewStubPeriodProducer(opt StubPeriodProducerOptions) *StubPeriodProducer {
+	s := new(StubPeriodProducer)
+	s.last = opt.Last
+	s.periods = opt.Periods
+	return s
+}
+
+type StubPeriodProducer struct {
+	last    *PeriodBound // для отдельного запроса
+	periods []stubPeriod
+	idx     int
+}
+
+func (s *StubPeriodProducer) Next() (period time.Time, first PeriodBound, last PeriodBound, found bool, err error) {
+	if s.idx < len(s.periods) {
+		p := s.periods[s.idx]
+		s.idx++
+		period = p.Period
+		first = p.First
+		last = p.Last
+		found = true
+	}
+	return
+}
+
+func (s *StubPeriodProducer) Last() (next PeriodBound, found bool, err error) {
+	if s.last != nil {
+		next = *s.last
+		found = true
+	}
+	return
+}