mirror of
https://github.com/dolthub/dolt.git
synced 2026-04-22 11:29:06 -05:00
Aaron Son
114 lines
2.8 KiB
Go
114 lines
2.8 KiB
Go
// Copyright 2019 Dolthub, 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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//
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// This file incorporates work covered by the following copyright and
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// permission notice:
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//
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// Copyright 2016 Attic Labs, Inc. All rights reserved.
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// Licensed under the Apache License, version 2.0:
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// http://www.apache.org/licenses/LICENSE-2.0
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package chunks
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import (
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"bytes"
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"encoding/binary"
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"io"
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"github.com/dolthub/dolt/go/store/d"
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"github.com/dolthub/dolt/go/store/hash"
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)
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/*
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Chunk Serialization:
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Chunk 0
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Chunk 1
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..
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Chunk N
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Chunk:
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Hash // 20-byte hash
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Len // 4-byte int
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Data // len(Data) == Len
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*/
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// Serialize a single Chunk to writer.
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func Serialize(chunk Chunk, writer io.Writer) {
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d.PanicIfFalse(chunk.data != nil)
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h := chunk.Hash()
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n, err := io.Copy(writer, bytes.NewReader(h[:]))
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d.Chk.NoError(err)
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d.PanicIfFalse(int64(hash.ByteLen) == n)
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// Because of chunking at higher levels, no chunk should never be more than 4GB
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chunkSize := uint32(len(chunk.Data()))
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err = binary.Write(writer, binary.BigEndian, chunkSize)
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d.Chk.NoError(err)
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n, err = io.Copy(writer, bytes.NewReader(chunk.Data()))
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d.Chk.NoError(err)
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d.PanicIfFalse(uint32(n) == chunkSize)
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}
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// Deserialize reads off of |reader| until EOF, sending chunks to
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// chunkChan in the order they are read. Objects sent over chunkChan are
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// *Chunk.
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func Deserialize(reader io.Reader, chunkChan chan<- *Chunk) (err error) {
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for {
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var c Chunk
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c, err = deserializeChunk(reader)
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if err != nil {
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break
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}
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d.Chk.NotEqual(EmptyChunk.Hash(), c.Hash())
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chunkChan <- &c
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}
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if err == io.EOF {
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err = nil
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}
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return
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}
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// DeserializeData deserializes a chunk from a byte array
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func DeserializeData(data []byte) (Chunk, error) {
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reader := bytes.NewReader(data)
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return deserializeChunk(reader)
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}
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func deserializeChunk(reader io.Reader) (Chunk, error) {
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h := hash.Hash{}
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n, err := io.ReadFull(reader, h[:])
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if err != nil {
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return EmptyChunk, err
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}
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d.PanicIfFalse(int(hash.ByteLen) == n)
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chunkSize := uint32(0)
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if err = binary.Read(reader, binary.BigEndian, &chunkSize); err != nil {
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return EmptyChunk, err
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}
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data := make([]byte, int(chunkSize))
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if n, err = io.ReadFull(reader, data); err != nil {
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return EmptyChunk, err
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}
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d.PanicIfFalse(int(chunkSize) == n)
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c := NewChunk(data)
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if h != c.Hash() {
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d.Panic("%s != %s", h, c.Hash().String())
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}
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return c, nil
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}
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