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88 lines
1.8 KiB
88 lines
1.8 KiB
package merkle
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import (
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"github.com/tendermint/tendermint/crypto/tmhash"
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cmn "github.com/tendermint/tendermint/libs/common"
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)
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// Merkle tree from a map.
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// Leaves are `hash(key) | hash(value)`.
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// Leaves are sorted before Merkle hashing.
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type simpleMap struct {
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kvs cmn.KVPairs
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sorted bool
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}
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func newSimpleMap() *simpleMap {
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return &simpleMap{
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kvs: nil,
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sorted: false,
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}
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}
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// Set hashes the key and value and appends it to the kv pairs.
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func (sm *simpleMap) Set(key string, value Hasher) {
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sm.sorted = false
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// The value is hashed, so you can
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// check for equality with a cached value (say)
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// and make a determination to fetch or not.
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vhash := value.Hash()
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sm.kvs = append(sm.kvs, cmn.KVPair{
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Key: []byte(key),
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Value: vhash,
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})
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}
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// Hash Merkle root hash of items sorted by key
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// (UNSTABLE: and by value too if duplicate key).
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func (sm *simpleMap) Hash() []byte {
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sm.Sort()
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return hashKVPairs(sm.kvs)
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}
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func (sm *simpleMap) Sort() {
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if sm.sorted {
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return
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}
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sm.kvs.Sort()
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sm.sorted = true
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}
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// Returns a copy of sorted KVPairs.
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// NOTE these contain the hashed key and value.
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func (sm *simpleMap) KVPairs() cmn.KVPairs {
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sm.Sort()
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kvs := make(cmn.KVPairs, len(sm.kvs))
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copy(kvs, sm.kvs)
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return kvs
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}
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//----------------------------------------
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// A local extension to KVPair that can be hashed.
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// Key and value are length prefixed and concatenated,
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// then hashed.
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type KVPair cmn.KVPair
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func (kv KVPair) Hash() []byte {
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hasher := tmhash.New()
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err := encodeByteSlice(hasher, kv.Key)
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if err != nil {
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panic(err)
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}
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err = encodeByteSlice(hasher, kv.Value)
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if err != nil {
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panic(err)
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}
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return hasher.Sum(nil)
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}
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func hashKVPairs(kvs cmn.KVPairs) []byte {
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kvsH := make([]Hasher, len(kvs))
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for i, kvp := range kvs {
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kvsH[i] = KVPair(kvp)
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}
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return SimpleHashFromHashers(kvsH)
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}
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