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