/
reader.go
443 lines (370 loc) · 11 KB
/
reader.go
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package floor
import (
"errors"
"fmt"
"io"
"os"
"reflect"
"time"
goparquet "github.com/fraugster/parquet-go"
"github.com/fraugster/parquet-go/floor/interfaces"
"github.com/fraugster/parquet-go/parquet"
"github.com/fraugster/parquet-go/parquetschema"
)
// NewReader returns a new high-level parquet file reader.
func NewReader(r *goparquet.FileReader) *Reader {
return &Reader{
r: r,
}
}
// NewFileReader returns a new high-level parquet file reader
// that directly reads from the provided file.
func NewFileReader(file string) (*Reader, error) {
f, err := os.Open(file)
if err != nil {
return nil, err
}
r, err := goparquet.NewFileReader(f)
if err != nil {
return nil, err
}
return &Reader{
r: r,
f: f,
}, nil
}
// Reader represents a high-level reader for parquet files.
type Reader struct {
r *goparquet.FileReader
f io.Closer
data map[string]interface{}
err error
eof bool
}
// Close closes the reader.
func (r *Reader) Close() error {
if r.f != nil {
return r.f.Close()
}
return nil
}
// Next reads the next object so that it is ready to be scanned.
// Returns true if fetching the next object was successful, false
// otherwise, e.g. in case of an error or when EOF was reached.
func (r *Reader) Next() bool {
r.data, r.err = r.r.NextRow()
if r.err == io.EOF {
r.eof = true
r.err = nil
return false
}
if r.err != nil {
return false
}
return true
}
// Scan fills obj with the data from the record last fetched.
// Returns an error if there is no data available or if the
// structure of obj doesn't fit the data. obj needs to be
// a pointer to an object, or alternatively implement the
// Unmarshaller interface.
func (r *Reader) Scan(obj interface{}) error {
if r.data == nil {
return errors.New("the Next function needs to be called before Scan can be called")
}
um, ok := obj.(interfaces.Unmarshaller)
if !ok {
um = &reflectUnmarshaller{obj: obj, schemaDef: r.r.GetSchemaDefinition()}
}
return um.UnmarshalParquet(interfaces.NewUnmarshallObject(r.data))
}
type reflectUnmarshaller struct {
obj interface{}
schemaDef *parquetschema.SchemaDefinition
}
func (um *reflectUnmarshaller) UnmarshalParquet(record interfaces.UnmarshalObject) error {
objValue := reflect.ValueOf(um.obj)
if objValue.Kind() != reflect.Ptr {
return fmt.Errorf("you need to provide an object of type *%T to unmarshal into", um.obj)
}
objValue = objValue.Elem()
if objValue.Kind() != reflect.Struct {
return fmt.Errorf("provided object of type %T is not a struct", um.obj)
}
if err := um.fillStruct(objValue, record, um.schemaDef); err != nil {
return err
}
return nil
}
func (um *reflectUnmarshaller) fillStruct(value reflect.Value, record interfaces.UnmarshalObject, schemaDef *parquetschema.SchemaDefinition) error {
typ := value.Type()
numFields := typ.NumField()
for i := 0; i < numFields; i++ {
fieldValue := value.Field(i)
fieldName := fieldNameFunc(typ.Field(i))
fieldSchemaDef := schemaDef.SubSchema(fieldName)
if fieldSchemaDef == nil {
continue
}
fieldData := record.GetField(fieldName)
if fieldData.Error() != nil {
if elem := fieldSchemaDef.SchemaElement(); elem.GetRepetitionType() == parquet.FieldRepetitionType_REQUIRED {
return fmt.Errorf("field %s is %s but couldn't be found in data", fieldName, elem.GetRepetitionType())
}
continue
}
if err := um.fillValue(fieldValue, fieldData, fieldSchemaDef); err != nil {
return err
}
}
return nil
}
func (um *reflectUnmarshaller) fillTimeValue(elem *parquet.SchemaElement, value reflect.Value, data interfaces.UnmarshalElement) error {
i, err := getIntValue(data)
if err != nil {
return err
}
var t Time
switch {
case elem.GetLogicalType().TIME.Unit.IsSetNANOS():
t = TimeFromNanoseconds(i)
case elem.GetLogicalType().TIME.Unit.IsSetMICROS():
t = TimeFromMicroseconds(i)
case elem.GetLogicalType().TIME.Unit.IsSetMILLIS():
t = TimeFromMilliseconds(int32(i))
default:
return errors.New("invalid TIME unit")
}
if elem.GetLogicalType().TIME.GetIsAdjustedToUTC() {
t = t.UTC()
}
value.Set(reflect.ValueOf(t))
return nil
}
func (um *reflectUnmarshaller) fillTimestampValue(elem *parquet.SchemaElement, value reflect.Value, data interfaces.UnmarshalElement) error {
i, err := getIntValue(data)
if err != nil {
return err
}
var ts time.Time
switch {
case elem.GetLogicalType().TIMESTAMP.Unit.IsSetNANOS():
ts = time.Unix(i/1000000000, i%1000000000)
case elem.GetLogicalType().TIMESTAMP.Unit.IsSetMICROS():
ts = time.Unix(i/1000000, 1000*(i%1000000))
case elem.GetLogicalType().TIMESTAMP.Unit.IsSetMILLIS():
ts = time.Unix(i/1000, 1000000*(i%1000))
default:
return errors.New("invalid TIMESTAMP unit")
}
if elem.GetLogicalType().TIMESTAMP.GetIsAdjustedToUTC() {
ts = ts.UTC()
}
value.Set(reflect.ValueOf(ts))
return nil
}
func (um *reflectUnmarshaller) fillDateValue(value reflect.Value, data interfaces.UnmarshalElement) error {
i, err := getIntValue(data)
if err != nil {
return err
}
date := time.Unix(0, 0).UTC().Add(24 * time.Hour * time.Duration(i))
value.Set(reflect.ValueOf(date))
return nil
}
func (um *reflectUnmarshaller) fillValue(value reflect.Value, data interfaces.UnmarshalElement, schemaDef *parquetschema.SchemaDefinition) error {
if value.Kind() == reflect.Ptr {
value.Set(reflect.New(value.Type().Elem()))
value = value.Elem()
}
if !value.CanSet() {
return nil
}
if value.Type().ConvertibleTo(reflect.TypeOf(Time{})) {
if elem := schemaDef.SchemaElement(); elem.LogicalType != nil && elem.GetLogicalType().IsSetTIME() {
return um.fillTimeValue(elem, value, data)
}
}
if value.Type().ConvertibleTo(reflect.TypeOf(time.Time{})) {
if elem := schemaDef.SchemaElement(); elem.LogicalType != nil {
switch {
case elem.GetLogicalType().IsSetDATE():
return um.fillDateValue(value, data)
case elem.GetLogicalType().IsSetTIMESTAMP():
return um.fillTimestampValue(elem, value, data)
}
} else if elem.GetType() == parquet.Type_INT96 {
i96, err := data.Int96()
if err != nil {
return err
}
value.Set(reflect.ValueOf(goparquet.Int96ToTime(i96).UTC()))
return nil
}
}
switch value.Kind() {
case reflect.Bool:
b, err := data.Bool()
if err != nil {
return err
}
value.SetBool(b)
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
i, err := getIntValue(data)
if err != nil {
return err
}
value.SetInt(i)
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
u, err := getIntValue(data)
if err != nil {
return err
}
value.SetUint(uint64(u))
case reflect.Float32, reflect.Float64:
f, err := getFloatValue(data)
if err != nil {
return err
}
value.SetFloat(f)
case reflect.Array, reflect.Slice:
if value.Type().Elem().Kind() == reflect.Uint8 {
return um.fillByteArrayOrSlice(value, data, schemaDef)
}
return um.fillArrayOrSlice(value, data, schemaDef)
case reflect.Map:
return um.fillMap(value, data, schemaDef)
case reflect.String:
s, err := data.ByteArray()
if err != nil {
return err
}
value.SetString(string(s))
case reflect.Struct:
groupData, err := data.Group()
if err != nil {
return err
}
if err := um.fillStruct(value, groupData, schemaDef); err != nil {
return err
}
default:
return fmt.Errorf("unsupported type %s", value.Type())
}
return nil
}
func (um *reflectUnmarshaller) fillMap(value reflect.Value, data interfaces.UnmarshalElement, schemaDef *parquetschema.SchemaDefinition) error {
if elem := schemaDef.SchemaElement(); elem.GetConvertedType() != parquet.ConvertedType_MAP {
return fmt.Errorf("filling map but schema element %s is not annotated as MAP", elem.GetName())
}
keyValueList, err := data.Map()
if err != nil {
return err
}
value.Set(reflect.MakeMap(value.Type()))
keyValueSchemaDef := schemaDef.SubSchema("key_value")
keySchemaDef := keyValueSchemaDef.SubSchema("key")
valueSchemaDef := keyValueSchemaDef.SubSchema("value")
for keyValueList.Next() {
key, err := keyValueList.Key()
if err != nil {
return err
}
valueData, err := keyValueList.Value()
if err != nil {
return err
}
keyValue := reflect.New(value.Type().Key()).Elem()
if err := um.fillValue(keyValue, key, keySchemaDef); err != nil {
return fmt.Errorf("couldn't fill key with key data: %v", err)
}
valueValue := reflect.New(value.Type().Elem()).Elem()
if err := um.fillValue(valueValue, valueData, valueSchemaDef); err != nil {
return fmt.Errorf("couldn't fill value with value data: %v", err)
}
value.SetMapIndex(keyValue, valueValue)
}
return nil
}
func (um *reflectUnmarshaller) fillByteArrayOrSlice(value reflect.Value, data interfaces.UnmarshalElement, schemaDef *parquetschema.SchemaDefinition) error {
byteSlice, err := data.ByteArray()
if err != nil {
return err
}
if value.Kind() == reflect.Slice {
value.Set(reflect.MakeSlice(value.Type(), len(byteSlice), len(byteSlice)))
}
for i, b := range byteSlice {
if i < value.Len() {
value.Index(i).SetUint(uint64(b))
}
}
return nil
}
func (um *reflectUnmarshaller) fillArrayOrSlice(value reflect.Value, data interfaces.UnmarshalElement, schemaDef *parquetschema.SchemaDefinition) error {
if elem := schemaDef.SchemaElement(); elem.GetConvertedType() != parquet.ConvertedType_LIST {
return fmt.Errorf("filling slice or array but schema element %s is not annotated as LIST", elem.GetName())
}
elemList, err := data.List()
if err != nil {
return err
}
elementList := []interfaces.UnmarshalElement{}
for elemList.Next() {
elemValue, err := elemList.Value()
if err != nil {
return err
}
elementList = append(elementList, elemValue)
}
if value.Kind() == reflect.Slice {
value.Set(reflect.MakeSlice(value.Type(), len(elementList), len(elementList)))
}
elemSchemaDef := schemaDef.SubSchema("list").SubSchema("element")
if elemSchemaDef == nil {
elemSchemaDef = schemaDef.SubSchema("bag").SubSchema("array_element")
if elemSchemaDef == nil {
return fmt.Errorf("element %s is annotated as LIST but group structure seems invalid", schemaDef.SchemaElement().GetName())
}
}
for idx, elem := range elementList {
if idx < value.Len() {
if err := um.fillValue(value.Index(idx), elem, elemSchemaDef); err != nil {
return err
}
}
}
return nil
}
func getIntValue(data interfaces.UnmarshalElement) (int64, error) {
i32, err := data.Int32()
if err == nil {
return int64(i32), nil
}
i64, err := data.Int64()
if err == nil {
return i64, nil
}
return 0, err
}
func getFloatValue(data interfaces.UnmarshalElement) (float64, error) {
f32, err := data.Float32()
if err == nil {
return float64(f32), nil
}
f64, err := data.Float64()
if err == nil {
return f64, nil
}
return 0, err
}
// Err returns an error in case Next returned false due to an error.
// If Next returned false due to EOF, Err returns nil.
func (r *Reader) Err() error {
return r.err
}
// GetSchemaDefinition returns the schema definition of the parquet
// file.
func (r *Reader) GetSchemaDefinition() *parquetschema.SchemaDefinition {
return r.r.GetSchemaDefinition()
}