101 lines
2.1 KiB
Go
101 lines
2.1 KiB
Go
package state
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import (
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"errors"
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"math/rand"
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"github.com/tendermint/tmlibs/merkle"
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)
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// store nonce as it's own type so no one can even try to fake it
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type nonce int64
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// Bonsai is a deformed tree forced to fit in a small pot
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type Bonsai struct {
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id nonce
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merkle.Tree
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}
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var _ SimpleDB = &Bonsai{}
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// NewBonsai wraps a merkle tree and tags it to track children
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func NewBonsai(tree merkle.Tree) *Bonsai {
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return &Bonsai{
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id: nonce(rand.Int63()),
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Tree: tree,
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}
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}
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// Get matches the signature of KVStore
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func (b *Bonsai) Get(key []byte) []byte {
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_, value, _ := b.Tree.Get(key)
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return value
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}
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// Set matches the signature of KVStore
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func (b *Bonsai) Set(key, value []byte) {
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b.Tree.Set(key, value)
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}
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func (b *Bonsai) Remove(key []byte) (value []byte) {
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value, _ = b.Tree.Remove(key)
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return
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}
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func (b *Bonsai) List(start, end []byte, limit int) []Model {
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res := []Model{}
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stopAtCount := func(key []byte, value []byte) (stop bool) {
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m := Model{key, value}
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res = append(res, m)
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// return false
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return limit > 0 && len(res) >= limit
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}
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b.Tree.IterateRange(start, end, true, stopAtCount)
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return res
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}
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func (b *Bonsai) First(start, end []byte) Model {
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var m Model
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stopAtFirst := func(key []byte, value []byte) (stop bool) {
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m = Model{key, value}
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return true
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}
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b.Tree.IterateRange(start, end, true, stopAtFirst)
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return m
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}
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func (b *Bonsai) Last(start, end []byte) Model {
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var m Model
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stopAtFirst := func(key []byte, value []byte) (stop bool) {
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m = Model{key, value}
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return true
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}
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b.Tree.IterateRange(start, end, false, stopAtFirst)
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return m
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}
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func (b *Bonsai) Checkpoint() SimpleDB {
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return &Bonsai{
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id: b.id,
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Tree: b.Tree.Copy(),
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}
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}
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// Commit will take all changes from the checkpoint and write
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// them to the parent.
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// Returns an error if this is not a child of this one
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func (b *Bonsai) Commit(sub SimpleDB) error {
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bb, ok := sub.(*Bonsai)
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if !ok || (b.id != bb.id) {
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return errors.New("Not a sub-transaction")
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}
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b.Tree = bb.Tree
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return nil
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}
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// Discard will remove reference to this
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func (b *Bonsai) Discard() {
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b.id = 0
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b.Tree = nil
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}
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