PKGBUILD/pkg/storage/storage.go

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package storage
import (
"context"
"fmt"
"math"
"net/url"
"sort"
"github.com/go-flucky/flucky/pkg/internal/format"
"github.com/go-flucky/flucky/pkg/storage/db"
"github.com/go-flucky/flucky/pkg/storage/logfile"
"github.com/go-flucky/flucky/pkg/types"
)
// Compression the measured values. The system checks whether the measured values
// of the same type correspond to those of the predecessor. If this is the case,
// the current value is discarded and the validity date of the previous value is
// set to that of the current value. This means that no information is lost.
// Only the validity period of the measured value is increased.
func Compression(measuredValues []*types.MeasuredValue) []*types.MeasuredValue {
compressedMeasuredValues := make([]*types.MeasuredValue, 0)
lastMeasuredValuesBySensors := make(map[string]map[types.MeasuredValueType]*types.MeasuredValue, 0)
// Sort all measured values according to the start time of the validity date
// in order to successfully implement the subsequent compression.
sort.SliceStable(measuredValues, func(i int, j int) bool {
return measuredValues[i].FromDate.Before(measuredValues[j].TillDate)
})
now := format.FormatedTime()
for _, measuredValue := range measuredValues {
// If the sensor id does not exist in the map, a new map is initialized,
// which can assume measured value types as the key. Behind this key there
// is a pointer which refers to a measured value in the memory. This new map
// is added to the map "lastMeasuredValuesBySensors" under the sensor ID.
// This makes it possible to store one measured value per measured value
// type per sensor.
if _, ok := lastMeasuredValuesBySensors[measuredValue.SensorID]; !ok {
lastMeasuredValuesBySensors[measuredValue.SensorID] = make(map[types.MeasuredValueType]*types.MeasuredValue, 0)
}
if _, ok := lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType]; !ok {
lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType] = measuredValue
continue
}
if lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType].Value == measuredValue.Value {
lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType].TillDate = measuredValue.TillDate
lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType].UpdateDate = &now
} else if lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType].Value != measuredValue.Value {
compressedMeasuredValues = append(compressedMeasuredValues, lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType])
delete(lastMeasuredValuesBySensors[measuredValue.SensorID], measuredValue.ValueType)
lastMeasuredValuesBySensors[measuredValue.SensorID][measuredValue.ValueType] = measuredValue
}
}
// Copy all remaining entries from the map into the cache array
for _, lastMeasuredValuesBySensor := range lastMeasuredValuesBySensors {
for _, measuredValueType := range types.MeasuredValueTypes {
if measuredValue, ok := lastMeasuredValuesBySensor[measuredValueType]; ok {
compressedMeasuredValues = append(compressedMeasuredValues, measuredValue)
}
}
}
// Sort all measured values again to include the measured values from the
// cache.
sort.SliceStable(compressedMeasuredValues, func(i int, j int) bool {
return compressedMeasuredValues[i].FromDate.Before(compressedMeasuredValues[j].FromDate)
})
return compressedMeasuredValues
}
// Read measured values from the given storage endpoint url. The scheme must be
// matched to a provider, if the scheme is not implemented, the function
// returns an error
func Read(ctx context.Context, storageEndpoint *url.URL) ([]*types.MeasuredValue, error) {
switch storageEndpoint.Scheme {
case "file":
measuredValueLogfile := logfile.New(storageEndpoint.Path)
return measuredValueLogfile.Read()
case "postgres":
database, err := db.New(storageEndpoint)
if err != nil {
return nil, err
}
defer database.Close()
return database.SelectMeasuredValues(ctx)
}
return nil, fmt.Errorf("No supported scheme")
}
func Round(measuredValues []*types.MeasuredValue, round float64) {
for _, measuredValue := range measuredValues {
measuredValue.Value = math.Round(measuredValue.Value/round) * round
}
}
// Write measured values to the given storage endpoint url. If the storage
// provider defined to a file, the data will be overwritten. If a database
// provider is used, the data is simply added without deleting the existing
// data. The scheme must be matched to a storage provider, if the scheme is not
// implemented, the function returns an error
func Write(ctx context.Context, measuredValues []*types.MeasuredValue, storageEndpoint *url.URL) error {
switch storageEndpoint.Scheme {
case "file":
measuredValueLogfile := logfile.New(storageEndpoint.Path)
storedMeasuredValues, err := measuredValueLogfile.Read()
if err != nil {
return err
}
storedMeasuredValues = append(storedMeasuredValues, measuredValues...)
return measuredValueLogfile.Write(storedMeasuredValues)
case "postgres":
database, err := db.New(storageEndpoint)
if err != nil {
return err
}
defer database.Close()
if err := database.InsertMeasuredValues(ctx, measuredValues); err != nil {
return err
}
}
return fmt.Errorf("No supported scheme")
}