Files
tidb/pkg/objstore/objectio/writer.go

156 lines
3.8 KiB
Go

// Copyright 2026 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package objectio
import (
"bytes"
"context"
"io"
"github.com/pingcap/errors"
"github.com/pingcap/tidb/pkg/objstore/compressedio"
"github.com/pingcap/tidb/pkg/objstore/recording"
)
// EmptyFlusher empty Flusher.
type EmptyFlusher struct{}
// Flush do flush.
func (*EmptyFlusher) Flush() error {
return nil
}
type interceptBuffer interface {
io.WriteCloser
compressedio.Flusher
Len() int
Cap() int
Bytes() []byte
Reset()
Compressed() bool
}
func newInterceptBuffer(chunkSize int, compressType compressedio.CompressType) interceptBuffer {
if compressType == compressedio.NoCompression {
return newPlainBuffer(chunkSize)
}
return compressedio.NewBuffer(chunkSize, compressType)
}
type plainBuffer struct {
*bytes.Buffer
}
func (*plainBuffer) Flush() error {
return nil
}
func (*plainBuffer) Close() error {
return nil
}
func (*plainBuffer) Compressed() bool {
return false
}
func newPlainBuffer(chunkSize int) *plainBuffer {
return &plainBuffer{bytes.NewBuffer(make([]byte, 0, chunkSize))}
}
// BufferedWriter is a buffered writer
type BufferedWriter struct {
buf interceptBuffer
writer Writer
accessRec *recording.AccessStats
}
// Write implements Writer.
func (u *BufferedWriter) Write(ctx context.Context, p []byte) (int, error) {
n, err := u.write0(ctx, p)
u.accessRec.RecWrite(n)
return n, errors.Trace(err)
}
func (u *BufferedWriter) write0(ctx context.Context, p []byte) (int, error) {
bytesWritten := 0
for u.buf.Len()+len(p) > u.buf.Cap() {
// We won't fit p in this chunk
// Is this chunk full?
chunkToFill := u.buf.Cap() - u.buf.Len()
if chunkToFill > 0 {
// It's not full so we write enough of p to fill it
prewrite := p[0:chunkToFill]
w, err := u.buf.Write(prewrite)
bytesWritten += w
if err != nil {
return bytesWritten, errors.Trace(err)
}
p = p[w:]
// continue buf because compressed data size may be less than Cap - Len
if u.buf.Compressed() {
continue
}
}
_ = u.buf.Flush()
err := u.uploadChunk(ctx)
if err != nil {
return 0, errors.Trace(err)
}
}
w, err := u.buf.Write(p)
bytesWritten += w
return bytesWritten, errors.Trace(err)
}
func (u *BufferedWriter) uploadChunk(ctx context.Context) error {
if u.buf.Len() == 0 {
return nil
}
b := u.buf.Bytes()
u.buf.Reset()
_, err := u.writer.Write(ctx, b)
return errors.Trace(err)
}
// Close implements Writer.
func (u *BufferedWriter) Close(ctx context.Context) error {
u.buf.Close()
err := u.uploadChunk(ctx)
if err != nil {
return errors.Trace(err)
}
return u.writer.Close(ctx)
}
// GetWriter get the underlying writer.
func (u *BufferedWriter) GetWriter() Writer {
return u.writer
}
// NewUploaderWriter wraps the Writer interface over an uploader.
func NewUploaderWriter(writer Writer, chunkSize int, compressType compressedio.CompressType) Writer {
return NewBufferedWriter(writer, chunkSize, compressType, nil)
}
// NewBufferedWriter is used to build a buffered writer.
func NewBufferedWriter(writer Writer, chunkSize int, compressType compressedio.CompressType, accessRec *recording.AccessStats) *BufferedWriter {
return &BufferedWriter{
writer: writer,
buf: newInterceptBuffer(chunkSize, compressType),
accessRec: accessRec,
}
}