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needle read into a writer

pull/3140/head
chrislu 3 years ago
parent
commit
685643d506
  1. 26
      weed/storage/needle/needle_read_page.go
  2. 20
      weed/storage/needle/needle_read_test.go

26
weed/storage/needle/needle_read_page.go

@ -9,6 +9,32 @@ import (
"io"
)
// ReadNeedleDataInto uses a needle without n.Data to read the content into an io.Writer
func (n *Needle) ReadNeedleDataInto(r backend.BackendStorageFile, offset int64, buf []byte, writer io.Writer, expectedChecksumValue uint32) (err error) {
crc := CRC(0)
for x := 0; ; x += len(buf) {
count, err := n.ReadNeedleData(r, offset, buf, int64(x))
if err != nil {
if err == io.EOF {
break
}
return fmt.Errorf("ReadNeedleData: %v", err)
}
if count > 0 {
crc = crc.Update(buf[0:count])
if _, err = writer.Write(buf[0:count]); err != nil {
return fmt.Errorf("ReadNeedleData write: %v", err)
}
} else {
break
}
}
if expectedChecksumValue != crc.Value() {
return fmt.Errorf("ReadNeedleData checksum %v expected %v", crc.Value(), expectedChecksumValue)
}
return nil
}
// ReadNeedleData uses a needle without n.Data to read the content
// volumeOffset: the offset within the volume
// needleOffset: the offset within the needle Data

20
weed/storage/needle/needle_read_test.go

@ -3,7 +3,6 @@ package needle
import (
"fmt"
"github.com/chrislusf/seaweedfs/weed/storage/backend"
"github.com/stretchr/testify/assert"
"io"
"os"
"testing"
@ -75,24 +74,9 @@ func TestPageRead(t *testing.T) {
fmt.Printf("Checksum value %d\n", checksumValue)
buf := make([]byte, 1024)
crc := CRC(0)
for x := int64(0); ; x += 1024 {
count, err := n.ReadNeedleData(datBackend, offset, buf, x)
if err != nil {
if err == io.EOF {
break
}
t.Fatalf("ReadNeedleData: %v", err)
}
if count > 0 {
crc = crc.Update(buf[0:count])
} else {
break
}
if err = n.ReadNeedleDataInto(datBackend, offset, buf, io.Discard, checksumValue); err != nil {
t.Fatalf("ReadNeedleDataInto: %v", err)
}
fmt.Printf("read checksum value %d\n", crc.Value())
assert.Equal(t, checksumValue, crc.Value(), "validate checksum value")
}

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