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utils.go
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utils.go
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package types
import (
"bytes"
cmn "github.com/tendermint/tendermint/libs/common"
)
// Iterator over all the keys with a certain prefix in ascending order
func KVStorePrefixIterator(kvs KVStore, prefix []byte) Iterator {
return kvs.Iterator(prefix, PrefixEndBytes(prefix))
}
// Iterator over all the keys with a certain prefix in descending order.
func KVStoreReversePrefixIterator(kvs KVStore, prefix []byte) Iterator {
return kvs.ReverseIterator(prefix, PrefixEndBytes(prefix))
}
// DiffKVStores compares two KVstores and returns all the key/value pairs
// that differ from one another. It also skips value comparison for a set of provided prefixes
func DiffKVStores(a KVStore, b KVStore, prefixesToSkip [][]byte) (kvs []cmn.KVPair) {
iterA := a.Iterator(nil, nil)
iterB := b.Iterator(nil, nil)
for {
if !iterA.Valid() && !iterB.Valid() {
break
}
var kvA, kvB cmn.KVPair
if iterA.Valid() {
kvA = cmn.KVPair{Key: iterA.Key(), Value: iterA.Value()}
iterA.Next()
}
if iterB.Valid() {
kvB = cmn.KVPair{Key: iterB.Key(), Value: iterB.Value()}
iterB.Next()
}
if !bytes.Equal(kvA.Key, kvB.Key) {
kvs = append(kvs, []cmn.KVPair{kvA, kvB}...)
}
compareValue := true
for _, prefix := range prefixesToSkip {
// Skip value comparison if we matched a prefix
if bytes.Equal(kvA.Key[:len(prefix)], prefix) {
compareValue = false
}
}
if compareValue && !bytes.Equal(kvA.Value, kvB.Value) {
kvs = append(kvs, []cmn.KVPair{kvA, kvB}...)
}
}
return
}
// PrefixEndBytes returns the []byte that would end a
// range query for all []byte with a certain prefix
// Deals with last byte of prefix being FF without overflowing
func PrefixEndBytes(prefix []byte) []byte {
if len(prefix) == 0 {
return nil
}
end := make([]byte, len(prefix))
copy(end, prefix)
for {
if end[len(end)-1] != byte(255) {
end[len(end)-1]++
break
} else {
end = end[:len(end)-1]
if len(end) == 0 {
end = nil
break
}
}
}
return end
}
// InclusiveEndBytes returns the []byte that would end a
// range query such that the input would be included
func InclusiveEndBytes(inclusiveBytes []byte) (exclusiveBytes []byte) {
exclusiveBytes = append(inclusiveBytes, byte(0x00))
return exclusiveBytes
}
//----------------------------------------
func Cp(bz []byte) (ret []byte) {
if bz == nil {
return nil
}
ret = make([]byte, len(bz))
copy(ret, bz)
return ret
}