added more test

store/cachekvstore.go

@@ -5,6 +5,7 @@ import (
 	"sort"
 	"sync"
 
+	sdk "github.com/cosmos/cosmos-sdk/types"
 	cmn "github.com/tendermint/tmlibs/common"
 )
 
@@ -134,6 +135,16 @@ func (ci *cacheKVStore) ReverseIterator(start, end []byte) Iterator {
 	return ci.iterator(start, end, false)
 }
 
+// Implements KVStore.
+func (ci *cacheKVStore) Subspace(prefix []byte) Iterator {
+	return ci.iterator(prefix, sdk.PrefixEndBytes(prefix), true)
+}
+
+// Implements KVStore.
+func (ci *cacheKVStore) ReverseSubspace(prefix []byte) Iterator {
+	return ci.iterator(prefix, sdk.PrefixEndBytes(prefix), false)
+}
+
 func (ci *cacheKVStore) iterator(start, end []byte, ascending bool) Iterator {
 	var parent, cache Iterator
 	if ascending {

store/dbstoreadapter.go

@@ -19,5 +19,13 @@ func (dsa dbStoreAdapter) CacheWrap() CacheWrap {
 	return NewCacheKVStore(dsa)
 }
 
+func (dsa dbStoreAdapter) Subspace(prefix []byte) Iterator {
+	return dsa.Iterator(prefix, sdk.PrefixEndBytes(prefix))
+}
+
+func (dsa dbStoreAdapter) ReverseSubspace(prefix []byte) Iterator {
+	return dsa.ReverseIterator(prefix, sdk.PrefixEndBytes(prefix))
+}
+
 // dbm.DB implements KVStore so we can CacheKVStore it.
 var _ KVStore = dbStoreAdapter{dbm.DB(nil)}

store/iavlstore.go

@@ -119,33 +119,21 @@ func (st *iavlStore) Iterator(start, end []byte) Iterator {
 	return newIAVLIterator(st.tree.Tree(), start, end, true)
 }
 
-func (st *iavlStore) Subspace(prefix []byte) Iterator {
-	end := make([]byte, len(prefix))
-	copy(end, prefix)
-	finished := false
-	i := 1
-
-	for !finished {
-		if end[len(end)-i] != byte(255) {
-			end[len(end)-i]++
-			finished = true
-		} else {
-			end[len(end)-i]++
-			i++
-			if i > len(end) {
-				end = nil
-				finished = true
-			}
-		}
-	}
-	return st.Iterator(prefix, end)
-}
-
-// Implements IterKVStore.
+// Implements KVStore.
 func (st *iavlStore) ReverseIterator(start, end []byte) Iterator {
 	return newIAVLIterator(st.tree.Tree(), start, end, false)
 }
 
+// Implements KVStore.
+func (st *iavlStore) Subspace(prefix []byte) Iterator {
+	return st.Iterator(prefix, sdk.PrefixEndBytes(prefix))
+}
+
+// Implements KVStore.
+func (st *iavlStore) ReverseSubspace(prefix []byte) Iterator {
+	return st.ReverseIterator(prefix, sdk.PrefixEndBytes(prefix))
+}
+
 // Query implements ABCI interface, allows queries
 //
 // by default we will return from (latest height -1),

store/iavlstore_test.go

@@ -198,6 +198,65 @@ func TestIAVLSubspace(t *testing.T) {
 	assert.Equal(t, len(expected), i)
 }
 
+func TestIAVLReverseSubspace(t *testing.T) {
+	db := dbm.NewMemDB()
+	tree, _ := newTree(t, db)
+	iavlStore := newIAVLStore(tree, numHistory)
+
+	iavlStore.Set([]byte("test1"), []byte("test1"))
+	iavlStore.Set([]byte("test2"), []byte("test2"))
+	iavlStore.Set([]byte("test3"), []byte("test3"))
+	iavlStore.Set([]byte{byte(55), byte(255), byte(255), byte(0)}, []byte("test4"))
+	iavlStore.Set([]byte{byte(55), byte(255), byte(255), byte(1)}, []byte("test4"))
+	iavlStore.Set([]byte{byte(55), byte(255), byte(255), byte(255)}, []byte("test4"))
+	iavlStore.Set([]byte{byte(255), byte(255), byte(0)}, []byte("test4"))
+	iavlStore.Set([]byte{byte(255), byte(255), byte(1)}, []byte("test4"))
+	iavlStore.Set([]byte{byte(255), byte(255), byte(255)}, []byte("test4"))
+
+	i := 0
+
+	iter := iavlStore.ReverseSubspace([]byte("test"))
+	expected := []string{"test3", "test2", "test1"}
+	for i = 0; iter.Valid(); iter.Next() {
+		expectedKey := expected[i]
+		key, value := iter.Key(), iter.Value()
+		assert.EqualValues(t, key, expectedKey)
+		assert.EqualValues(t, value, expectedKey)
+		i += 1
+	}
+	assert.Equal(t, len(expected), i)
+
+	iter = iavlStore.ReverseSubspace([]byte{byte(55), byte(255), byte(255)})
+	expected2 := [][]byte{
+		[]byte{byte(55), byte(255), byte(255), byte(255)},
+		[]byte{byte(55), byte(255), byte(255), byte(1)},
+		[]byte{byte(55), byte(255), byte(255), byte(0)},
+	}
+	for i = 0; iter.Valid(); iter.Next() {
+		expectedKey := expected2[i]
+		key, value := iter.Key(), iter.Value()
+		assert.EqualValues(t, key, expectedKey)
+		assert.EqualValues(t, value, []byte("test4"))
+		i += 1
+	}
+	assert.Equal(t, len(expected), i)
+
+	iter = iavlStore.ReverseSubspace([]byte{byte(255), byte(255)})
+	expected2 = [][]byte{
+		[]byte{byte(255), byte(255), byte(255)},
+		[]byte{byte(255), byte(255), byte(1)},
+		[]byte{byte(255), byte(255), byte(0)},
+	}
+	for i = 0; iter.Valid(); iter.Next() {
+		expectedKey := expected2[i]
+		key, value := iter.Key(), iter.Value()
+		assert.EqualValues(t, key, expectedKey)
+		assert.EqualValues(t, value, []byte("test4"))
+		i += 1
+	}
+	assert.Equal(t, len(expected), i)
+}
+
 func TestIAVLStoreQuery(t *testing.T) {
 	db := dbm.NewMemDB()
 	tree := iavl.NewVersionedTree(db, cacheSize)

types/store.go

@@ -111,6 +111,14 @@ type KVStore interface {
 	// CONTRACT: No writes may happen within a domain while an iterator exists over it.
 	ReverseIterator(start, end []byte) Iterator
 
+	// Iterator over all the keys with a certain prefix in ascending order.
+	// CONTRACT: No writes may happen within a domain while an iterator exists over it.
+	Subspace(prefix []byte) Iterator
+
+	// Iterator over all the keys with a certain prefix in descending order.
+	// CONTRACT: No writes may happen within a domain while an iterator exists over it.
+	ReverseSubspace(prefix []byte) Iterator
+
 	// TODO Not yet implemented.
 	// CreateSubKVStore(key *storeKey) (KVStore, error)
 
@@ -222,3 +230,28 @@ func (key *KVStoreKey) Name() string {
 func (key *KVStoreKey) String() string {
 	return fmt.Sprintf("KVStoreKey{%p, %s}", key, key.name)
 }
+
+// TODO: Move to TmLibs
+func PrefixEndBytes(prefix []byte) []byte {
+	if prefix == nil {
+		return nil
+	}
+
+	end := make([]byte, len(prefix))
+	copy(end, prefix)
+	finished := false
+
+	for !finished {
+		if end[len(end)-1] != byte(255) {
+			end[len(end)-1]++
+			finished = true
+		} else {
+			end = end[:len(end)-1]
+			if len(end) == 0 {
+				end = nil
+				finished = true
+			}
+		}
+	}
+	return end
+}