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accumulator.go
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/
accumulator.go
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/*
* Copyright 2021 ICON Foundation
*
* 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 hexary
import (
"github.com/icon-project/goloop/common/db"
"github.com/icon-project/goloop/common/errors"
)
type Accumulator interface {
Add(hash []byte) error
// Len returns number of added hashes.
Len() int64
// Finalize finalizes node data and write merkle tree data on the given
// key in tree bucket.
Finalize(key string) (rootHash []byte, length int64, err error)
}
type accumulatorData struct {
Len int64
Roots []*node
}
type accumulator struct {
data accumulatorData
treeBucket db.Bucket
accumulatorBucket *db.CodedBucket
accumulatorDataKey []byte
}
func (ba *accumulator) add(i int, hash []byte) error {
if i >= len(ba.data.Roots) {
ba.data.Roots = append(ba.data.Roots, newNode())
}
rb := ba.data.Roots[i]
rb.Add(hash)
if rb.Full() {
if err := ba.treeBucket.Set(rb.Hash(), rb.Bytes()); err != nil {
return err
}
hash := rb.Hash()
rb.Clear()
if err := ba.add(i+1, hash); err != nil {
return err
}
}
return nil
}
func (ba *accumulator) Add(hash []byte) error {
if err := ba.add(0, hash); err != nil {
return err
}
ba.data.Len++
return ba.accumulatorBucket.Set(ba.accumulatorDataKey, &ba.data)
}
func (ba *accumulator) Len() int64 {
return ba.data.Len
}
func (ba *accumulator) Finalize(merkleKey string) (rootHash []byte, length int64, err error) {
if len(merkleKey) == 0 {
merkleKey = defaultMerkleTreeKey
}
var prevHash []byte
for _, r := range ba.data.Roots {
if prevHash != nil {
r.Add(prevHash)
}
if err = ba.treeBucket.Set(r.Hash(), r.Bytes()); err != nil {
return nil, 0, err
}
prevHash = r.Hash()
}
root := ba.data.Roots[len(ba.data.Roots)-1]
if root.Len() != 1 {
root = newNode()
root.Add(prevHash)
if err = ba.treeBucket.Set(root.Hash(), root.Bytes()); err != nil {
return nil, 0, err
}
ba.data.Roots = append(ba.data.Roots, root)
}
mtd := merkleTreeData{
Cap: ba.data.Len,
RootHash: root.Get(0),
}
err = db.NewCodedBucketFromBucket(ba.treeBucket, nil).Set(merkleKey, &mtd)
if err != nil {
return nil, 0, err
}
return mtd.RootHash, mtd.Cap, nil
}
// NewAccumulator creates a new accumulator. Merkle node is written in tree
// bucket, accumulator is written on accumulator data key in accumulator bucket.
func NewAccumulator(
treeBucket db.Bucket,
accumulatorBucket db.Bucket,
accumulatorDataKey string,
) (Accumulator, error) {
ba := &accumulator{
treeBucket: treeBucket,
accumulatorBucket: db.NewCodedBucketFromBucket(accumulatorBucket, nil),
accumulatorDataKey: []byte(accumulatorDataKey),
}
err := ba.accumulatorBucket.Get(db.Raw(accumulatorDataKey), &ba.data)
if err != nil && !errors.NotFoundError.Equals(err) {
return nil, err
}
return ba, nil
}