Added nodata code

nodata.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	// External
+	werr "git.gibonuddevalla.se/go/wrappederror"
+
+	// Standard
+	"database/sql"
+	"time"
+)
+
+// nodataLoop  checks if datapoint last_value is larger than the nodata_problem_seconds period and
+// marks them as problems. They are then notified.
+func nodataLoop() {
+	var ids []int
+	var err error
+
+	// TODO - should be configurable
+	ticker := time.NewTicker(time.Second * 5)
+	for {
+		<-ticker.C
+		ids, err = nodataDatapointIDs()
+		if err != nil {
+			err = werr.Wrap(err).Log()
+			logger.Error("nodata", "error", err)
+			continue
+		}
+
+		if len(ids) == 0 {
+			continue
+		}
+
+		logger.Info("nodata", "problem_ids", ids)
+	}
+}
+
+func nodataDatapointIDs() (ids []int, err error) {
+	ids = []int{}
+
+	var rows *sql.Rows
+	rows, err = service.Db.Conn.Query(`
+		UPDATE datapoint
+		SET
+			nodata_is_problem = true
+		FROM (
+			SELECT
+				id
+			FROM
+				datapoint
+			WHERE
+				NOT nodata_is_problem AND
+				extract(EPOCH from (NOW() - last_value))::int > nodata_problem_seconds
+			) AS subquery
+		WHERE
+			datapoint.id = subquery.id
+		RETURNING
+			datapoint.id
+
+	`)
+	if err != nil {
+		err = werr.Wrap(err)
+		return
+	}
+	defer rows.Close()
+
+	var id int
+	for rows.Next() {
+		if err = rows.Scan(&id); err != nil {
+			err = werr.Wrap(err)
+			return
+		}
+		ids = append(ids, id)
+	}
+	return
+}