/
reader.go
76 lines (63 loc) · 2.13 KB
/
reader.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
// Copyright 2019 dfuse Platform 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 codec
import (
"fmt"
"io"
"github.com/dfuse-io/bstream"
"github.com/dfuse-io/dbin"
pbbstream "github.com/dfuse-io/pbgo/dfuse/bstream/v1"
"github.com/golang/protobuf/proto"
)
func BlockReaderFactory(reader io.Reader) (bstream.BlockReader, error) {
return NewBlockReader(reader)
}
// BlockReader reads the dbin format where each element is assumed to be a `bstream.Block`.
type BlockReader struct {
src *dbin.Reader
}
func NewBlockReader(reader io.Reader) (out *BlockReader, err error) {
dbinReader := dbin.NewReader(reader)
contentType, version, err := dbinReader.ReadHeader()
if err != nil {
return nil, fmt.Errorf("unable to read file header: %s", err)
}
protocol := pbbstream.Protocol(pbbstream.Protocol_value[contentType])
if protocol != pbbstream.Protocol_EOS && version != 1 {
return nil, fmt.Errorf("reader only knows about %s block kind at version 1, got %s at version %d", protocol, contentType, version)
}
return &BlockReader{
src: dbinReader,
}, nil
}
func (l *BlockReader) Read() (*bstream.Block, error) {
message, err := l.src.ReadMessage()
if len(message) > 0 && (err == nil || err == io.EOF) {
pbBlock := new(pbbstream.Block)
err = proto.Unmarshal(message, pbBlock)
if err != nil {
return nil, fmt.Errorf("unable to read block proto: %w", err)
}
blk, err := bstream.BlockFromProto(pbBlock)
if err != nil {
return nil, err
}
return blk, nil
}
if err == io.EOF {
return nil, err
}
// In all other cases, we are in an error path
return nil, fmt.Errorf("failed reading next dbin message: %w", err)
}