impl.go 4.54 KB
Newer Older
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
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
/*
Copyright IBM Corp. 2016 All Rights Reserved.

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 jsonledger

import (
	"bytes"
	"fmt"
	"os"
	"path/filepath"

	ledger "github.com/hyperledger/fabric/orderer/ledger"
	cb "github.com/hyperledger/fabric/protos/common"
	ab "github.com/hyperledger/fabric/protos/orderer"
	"github.com/op/go-logging"

	"github.com/golang/protobuf/jsonpb"
)

var logger = logging.MustGetLogger("orderer/jsonledger")
var closedChan chan struct{}

func init() {
	closedChan = make(chan struct{})
	close(closedChan)
}

const (
	blockFileFormatString      = "block_%020d.json"
	chainDirectoryFormatString = "chain_%s"
)

type cursor struct {
	jl          *jsonLedger
	blockNumber uint64
}

type jsonLedger struct {
	directory      string
	fqFormatString string
	height         uint64
	signal         chan struct{}
	lastHash       []byte
	marshaler      *jsonpb.Marshaler
}

// readBlock returns the block or nil, and whether the block was found or not, (nil,true) generally indicates an irrecoverable problem
func (jl *jsonLedger) readBlock(number uint64) (*cb.Block, bool) {
	file, err := os.Open(jl.blockFilename(number))
	if err == nil {
		defer file.Close()
		block := &cb.Block{}
		err = jsonpb.Unmarshal(file, block)
		if err != nil {
			return nil, true
		}
		logger.Debugf("Read block %d", block.Header.Number)
		return block, true
	}
	return nil, false
}

// Next blocks until there is a new block available, or returns an error if the
// next block is no longer retrievable
func (cu *cursor) Next() (*cb.Block, cb.Status) {
	// This only loops once, as signal reading
	// indicates the new block has been written
	for {
		block, found := cu.jl.readBlock(cu.blockNumber)
		if found {
			if block == nil {
				return nil, cb.Status_SERVICE_UNAVAILABLE
			}
			cu.blockNumber++
			return block, cb.Status_SUCCESS
		}
		<-cu.jl.signal
	}
}

// ReadyChan supplies a channel which will block until Next will not block
func (cu *cursor) ReadyChan() <-chan struct{} {
	signal := cu.jl.signal
	if _, err := os.Stat(cu.jl.blockFilename(cu.blockNumber)); os.IsNotExist(err) {
		return signal
	}
	return closedChan
}

// Iterator returns an Iterator, as specified by a cb.SeekInfo message, and its
// starting block number
func (jl *jsonLedger) Iterator(startPosition *ab.SeekPosition) (ledger.Iterator, uint64) {
	switch start := startPosition.Type.(type) {
	case *ab.SeekPosition_Oldest:
		return &cursor{jl: jl, blockNumber: 0}, 0
	case *ab.SeekPosition_Newest:
		high := jl.height - 1
		return &cursor{jl: jl, blockNumber: high}, high
	case *ab.SeekPosition_Specified:
		if start.Specified.Number > jl.height {
			return &ledger.NotFoundErrorIterator{}, 0
		}
		return &cursor{jl: jl, blockNumber: start.Specified.Number}, start.Specified.Number
	}

	// This line should be unreachable, but the compiler requires it
	return &ledger.NotFoundErrorIterator{}, 0
}

// Height returns the number of blocks on the ledger
func (jl *jsonLedger) Height() uint64 {
	return jl.height
}

// Append appends a new block to the ledger
func (jl *jsonLedger) Append(block *cb.Block) error {
	if block.Header.Number != jl.height {
		return fmt.Errorf("Block number should have been %d but was %d", jl.height, block.Header.Number)
	}

	if !bytes.Equal(block.Header.PreviousHash, jl.lastHash) {
		return fmt.Errorf("Block should have had previous hash of %x but was %x", jl.lastHash, block.Header.PreviousHash)
	}

	jl.writeBlock(block)
	jl.lastHash = block.Header.Hash()
	jl.height++
	close(jl.signal)
	jl.signal = make(chan struct{})
	return nil
}

// writeBlock commits a block to disk
func (jl *jsonLedger) writeBlock(block *cb.Block) {
	file, err := os.Create(jl.blockFilename(block.Header.Number))
	if err != nil {
		panic(err)
	}
	defer file.Close()
	err = jl.marshaler.Marshal(file, block)
	logger.Debugf("Wrote block %d", block.Header.Number)
	if err != nil {
		logger.Panic(err)
	}
}

// blockFilename returns the fully qualified path to where a block
// of a given number should be stored on disk
func (jl *jsonLedger) blockFilename(number uint64) string {
	return filepath.Join(jl.directory, fmt.Sprintf(blockFileFormatString, number))
}