102 lines
2.3 KiB
Go
102 lines
2.3 KiB
Go
// Copyright 2023 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package external
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import (
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"context"
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"io"
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"github.com/pingcap/errors"
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"github.com/pingcap/tidb/pkg/objstore"
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"github.com/pingcap/tidb/pkg/objstore/storeapi"
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"golang.org/x/sync/errgroup"
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)
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// concurrentFileReader reads a file with multiple chunks concurrently.
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type concurrentFileReader struct {
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ctx context.Context
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concurrency int
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readBufferSize int
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storage storeapi.Storage
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name string
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offset int64
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fileSize int64
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}
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// newConcurrentFileReader creates a new concurrentFileReader.
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func newConcurrentFileReader(
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ctx context.Context,
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st storeapi.Storage,
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name string,
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offset int64,
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fileSize int64,
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concurrency int,
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readBufferSize int,
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) (*concurrentFileReader, error) {
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return &concurrentFileReader{
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ctx: ctx,
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concurrency: concurrency,
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readBufferSize: readBufferSize,
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offset: offset,
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fileSize: fileSize,
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name: name,
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storage: st,
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}, nil
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}
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// read loads the file content concurrently into the buffer.
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func (r *concurrentFileReader) read(bufs [][]byte) ([][]byte, error) {
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if r.offset >= r.fileSize {
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return nil, io.EOF
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}
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ret := make([][]byte, 0, r.concurrency)
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eg := errgroup.Group{}
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for i := range r.concurrency {
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if r.offset >= r.fileSize {
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break
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}
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end := r.readBufferSize
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if r.offset+int64(end) > r.fileSize {
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end = int(r.fileSize - r.offset)
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}
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buf := bufs[i][:end]
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ret = append(ret, buf)
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offset := r.offset
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r.offset += int64(end)
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eg.Go(func() error {
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_, err := objstore.ReadDataInRange(
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r.ctx,
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r.storage,
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r.name,
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offset,
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buf,
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)
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if err != nil {
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return errors.Annotatef(err, "offset: %d, readSize: %d", offset, len(buf))
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}
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return nil
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})
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}
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err := eg.Wait()
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if err != nil {
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return nil, err
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}
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return ret, nil
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}
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