Merge pull request #486 from lionsoul2014/fr_go_binding_with_xdb_stream_input

xdb io.Reader based stream input supports

binding/golang/xdb/searcher.go

@@ -14,12 +14,13 @@ package xdb
 import (
 	"encoding/binary"
 	"fmt"
+	"io"
 	"os"
 )
 
 type Searcher struct {
 	version  *Version
-	handle  *os.File
+	dbReader io.ReadSeekCloser
 
 	ioCount int
 
@@ -65,14 +66,31 @@ func NewSearcher(version *Version, dbFile string, vIndex []byte, cBuff []byte) (
 
 	return &Searcher{
 		version:     version,
-		handle:      handle,
+		dbReader:    handle,
 		vectorIndex: vIndex,
 	}, nil
 }
 
+func INewSearcher(version *Version, dbReader io.ReadSeekCloser, vIndex []byte, cBuff []byte) *Searcher {
+	// content buff first
+	if cBuff != nil {
+		return &Searcher{
+			version:     version,
+			vectorIndex: nil,
+			contentBuff: cBuff,
+		}
+	} else {
+		return &Searcher{
+			version:     version,
+			dbReader:    dbReader,
+			vectorIndex: vIndex,
+		}
+	}
+}
+
 func (s *Searcher) Close() {
-	if s.handle != nil {
-		err := s.handle.Close()
+	if s.dbReader != nil {
+		err := s.dbReader.Close()
 		if err != nil {
 			// do error log here ?
 		}
@@ -193,13 +211,13 @@ func (s *Searcher) read(offset int64, buff []byte) error {
 			return fmt.Errorf("incomplete read: readed bytes should be %d", len(buff))
 		}
 	} else {
-		_, err := s.handle.Seek(offset, 0)
+		_, err := s.dbReader.Seek(offset, 0)
 		if err != nil {
 			return fmt.Errorf("seek to %d: %w", offset, err)
 		}
 
 		s.ioCount++
-		rLen, err := s.handle.Read(buff)
+		rLen, err := s.dbReader.Read(buff)
 		if err != nil {
 			return fmt.Errorf("handle read: %w", err)
 		}

binding/golang/xdb/util.go

@@ -185,7 +185,7 @@ func VerifyFromFile(dbFile string) error {
 }
 
 // LoadHeader load the header info from the specified handle
-func LoadHeader(handle *os.File) (*Header, error) {
+func LoadHeader(handle io.ReadSeeker) (*Header, error) {
 	_, err := handle.Seek(0, 0)
 	if err != nil {
 		return nil, fmt.Errorf("seek to the header: %w", err)
@@ -226,7 +226,7 @@ func LoadHeaderFromBuff(cBuff []byte) (*Header, error) {
 }
 
 // LoadVectorIndex util function to load the vector index from the specified file handle
-func LoadVectorIndex(handle *os.File) ([]byte, error) {
+func LoadVectorIndex(handle io.ReadSeeker) ([]byte, error) {
 	// load all the vector index block
 	_, err := handle.Seek(HeaderInfoLength, 0)
 	if err != nil {
@@ -263,32 +263,14 @@ func LoadVectorIndexFromFile(dbFile string) ([]byte, error) {
 }
 
 // LoadContent load the whole xdb content from the specified file handle
-func LoadContent(handle *os.File) ([]byte, error) {
-	// get file size
-	fi, err := handle.Stat()
-	if err != nil {
-		return nil, fmt.Errorf("stat: %w", err)
-	}
-
-	size := fi.Size()
-
+func LoadContent(handle io.ReadSeeker) ([]byte, error) {
 	// seek to the head of the file
-	_, err = handle.Seek(0, 0)
+	_, err := handle.Seek(0, 0)
 	if err != nil {
 		return nil, fmt.Errorf("seek to get xdb file length: %w", err)
 	}
 
-	var buff = make([]byte, size)
-	rLen, err := handle.Read(buff)
-	if err != nil {
-		return nil, err
-	}
-
-	if rLen != len(buff) {
-		return nil, fmt.Errorf("incomplete read: readed bytes should be %d", len(buff))
-	}
-
-	return buff, nil
+	return io.ReadAll(handle)
 }
 
 // LoadContentFromFile load the whole xdb content from the specified db file path