Add code to remove old data and switch the port to 8085

shroom_internals/sql.go

@@ -66,8 +66,32 @@ func LatestTime(db *sql.DB) (int64, error) {
 	return t, nil
 }
 
+func OldestTime(db *sql.DB) (int64, error) {
+	query := "SELECT MIN(time) FROM shrooms"
+	rows, err := db.Query(query)
+	if err != nil {
+		return -1, fmt.Errorf("sql error: %w", err)
+	}
+	defer rows.Close()
+	if !rows.Next() {
+		// i guess the database is empty
+		return 0, nil
+	}
+	t := int64(0)
+	err = rows.Scan(&t)
+	if err != nil {
+		return -1, fmt.Errorf("sql scan error: %w", err)
+	}
+	return t, nil
+}
+
 func InsertRow(db *sql.DB, s *DataJson) error {
 	_, err := db.Exec("INSERT INTO shrooms (time, temperature, humidity, humidifier_volts) VALUES (?, ?, ?, ?)",
 		*s.Time, *s.Temperature, *s.Humidity, *s.HumidifierVolts)
 	return err
 }
+
+func ClearOldRows(db *sql.DB, min_time int64) error {
+	_, err := db.Exec("DELETE FROM shrooms WHERE t < ?", min_time)
+	return err
+}

shroom_server.go

@@ -38,6 +38,8 @@ type adminMsg struct {
 	Msg  map[string]interface{} `json:"data"`
 }
 
+// returns a function that multiplies the number at the very last segment of the url
+// and returns the data that was collected in the last n*multiplier milliseconds
 func dumpData(db *sql.DB, multiplier int64) func(http.ResponseWriter, *http.Request) {
 	return func(w http.ResponseWriter, req *http.Request) {
 		now := time.Now().Unix()
@@ -200,9 +202,28 @@ func main() {
 	http.HandleFunc("/api/update", updateHandler)
 	http.HandleFunc("/api/status_update", statusUpdateHandler)
 
-	// TODO periodically clear old entries from the database
+	// periodically clear old entries from the database
+	go func() {
+		// TODO maybe make this exit gracefully
+		for {
+			t, err := s.OldestTime(db)
+			if err != nil {
+				log.Println("unable to get oldest time: ", err)
+			}
+			now := time.Now().Unix()
+			diff := now*1000 - t
+			log.Println("oldest time", t, " current time", now, "diff", diff)
+			if diff > 2*7*24*60*60*1000 {
+				err = s.ClearOldRows(db, now-8*24*60*60*1000)
+				if err != nil {
+					log.Println("unable to delete rows: ", err)
+				}
+			}
+			time.Sleep(24 * time.Hour)
+		}
+	}()
 
-	err = http.ListenAndServe("localhost:8080", nil)
+	err = http.ListenAndServe("localhost:8085", nil)
 	if err != nil {
 		log.Fatal("unable to start server: ", err)
 	}