Merge PR cosmos#4382: Support height queries for queriers

.pending/features/sdk/4318-Support-height-

@@ -0,0 +1,2 @@
+#4318 Support height queries. Queries against nodes that have the queried
+height pruned will return an error.

baseapp/baseapp.go

@@ -536,6 +536,15 @@ func handleQueryCustom(app *BaseApp, path []string, req abci.RequestQuery) (res
 		app.cms.CacheMultiStore(), app.checkState.ctx.BlockHeader(), true, app.logger,
 	).WithMinGasPrices(app.minGasPrices)
 
+	if req.Height > 0 {
+		cacheMS, err := app.cms.CacheMultiStoreWithVersion(req.Height)
+		if err != nil {
+			return sdk.ErrInternal(fmt.Sprintf("failed to load state at height %d; %s", req.Height, err)).QueryResult()
+		}
+
+		ctx = ctx.WithMultiStore(cacheMS)
+	}
+
 	// Passes the rest of the path as an argument to the querier.
 	//
 	// For example, in the path "custom/gov/proposal/test", the gov querier gets

client/flags/flags.go

@@ -71,7 +71,9 @@ func GetCommands(cmds ...*cobra.Command) []*cobra.Command {
 		c.Flags().Bool(FlagIndentResponse, false, "Add indent to JSON response")
 		c.Flags().Bool(FlagTrustNode, false, "Trust connected full node (don't verify proofs for responses)")
 		c.Flags().Bool(FlagUseLedger, false, "Use a connected Ledger device")
-		c.Flags().String(FlagNode, "tcp://localhost:26657", "<host>:<port> to tendermint rpc interface for this chain")
+		c.Flags().String(FlagNode, "tcp://localhost:26657", "<host>:<port> to Tendermint RPC interface for this chain")
+		c.Flags().Int64(FlagHeight, 0, "Use a specific height to query state at (this can error if the node is pruning state)")
+
 		viper.BindPFlag(FlagTrustNode, c.Flags().Lookup(FlagTrustNode))
 		viper.BindPFlag(FlagUseLedger, c.Flags().Lookup(FlagUseLedger))
 		viper.BindPFlag(FlagNode, c.Flags().Lookup(FlagNode))

server/mock/store.go

@@ -18,6 +18,10 @@ func (ms multiStore) CacheMultiStore() sdk.CacheMultiStore {
 	panic("not implemented")
 }
 
+func (kv multiStore) CacheMultiStoreWithVersion(_ int64) (sdk.CacheMultiStore, error) {
+	panic("not implemented")
+}
+
 func (ms multiStore) CacheWrap() sdk.CacheWrap {
 	panic("not implemented")
 }

store/cachemulti/store.go

@@ -124,6 +124,15 @@ func (cms Store) CacheMultiStore() types.CacheMultiStore {
 	return newCacheMultiStoreFromCMS(cms)
 }
 
+// CacheMultiStoreWithVersion implements the MultiStore interface. It will panic
+// as an already cached multi-store cannot load previous versions.
+//
+// TODO: The store implementation can possibly be modified to support this as it
+// seems safe to load previous versions (heights).
+func (cms Store) CacheMultiStoreWithVersion(_ int64) (types.CacheMultiStore, error) {
+	panic("cannot cache-wrap cached multi-store with a version")
+}
+
 // GetStore returns an underlying Store by key.
 func (cms Store) GetStore(key types.StoreKey) types.Store {
 	return cms.stores[key].(types.Store)

store/iavl/store.go

@@ -24,12 +24,15 @@ const (
 // load the iavl store
 func LoadStore(db dbm.DB, id types.CommitID, pruning types.PruningOptions) (types.CommitStore, error) {
 	tree := iavl.NewMutableTree(db, defaultIAVLCacheSize)
+
 	_, err := tree.LoadVersion(id.Version)
 	if err != nil {
 		return nil, err
 	}
+
 	iavl := UnsafeNewStore(tree, int64(0), int64(0))
 	iavl.SetPruning(pruning)
+
 	return iavl, nil
 }
 
@@ -41,8 +44,7 @@ var _ types.Queryable = (*Store)(nil)
 
 // Store Implements types.KVStore and CommitStore.
 type Store struct {
-	// The underlying tree.
-	tree *iavl.MutableTree
+	tree Tree
 
 	// How many old versions we hold onto.
 	// A value of 0 means keep no recent states.
@@ -68,6 +70,28 @@ func UnsafeNewStore(tree *iavl.MutableTree, numRecent int64, storeEvery int64) *
 	return st
 }
 
+// GetImmutable returns a reference to a new store backed by an immutable IAVL
+// tree at a specific version (height) without any pruning options. This should
+// be used for querying and iteration only. If the version does not exist or has
+// been pruned, an error will be returned. Any mutable operations executed will
+// result in a panic.
+func (st *Store) GetImmutable(version int64) (*Store, error) {
+	if !st.VersionExists(version) {
+		return nil, iavl.ErrVersionDoesNotExist
+	}
+
+	iTree, err := st.tree.GetImmutable(version)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Store{
+		tree:       &immutableTree{iTree},
+		numRecent:  0,
+		storeEvery: 0,
+	}, nil
+}
+
 // Implements Committer.
 func (st *Store) Commit() types.CommitID {
 	// Save a new version.
@@ -153,16 +177,34 @@ func (st *Store) Delete(key []byte) {
 
 // Implements types.KVStore.
 func (st *Store) Iterator(start, end []byte) types.Iterator {
-	return newIAVLIterator(st.tree.ImmutableTree, start, end, true)
+	var iTree *iavl.ImmutableTree
+
+	switch tree := st.tree.(type) {
+	case *immutableTree:
+		iTree = tree.ImmutableTree
+	case *iavl.MutableTree:
+		iTree = tree.ImmutableTree
+	}
+
+	return newIAVLIterator(iTree, start, end, true)
 }
 
 // Implements types.KVStore.
 func (st *Store) ReverseIterator(start, end []byte) types.Iterator {
-	return newIAVLIterator(st.tree.ImmutableTree, start, end, false)
+	var iTree *iavl.ImmutableTree
+
+	switch tree := st.tree.(type) {
+	case *immutableTree:
+		iTree = tree.ImmutableTree
+	case *iavl.MutableTree:
+		iTree = tree.ImmutableTree
+	}
+
+	return newIAVLIterator(iTree, start, end, false)
 }
 
 // Handle gatest the latest height, if height is 0
-func getHeight(tree *iavl.MutableTree, req abci.RequestQuery) int64 {
+func getHeight(tree Tree, req abci.RequestQuery) int64 {
 	height := req.Height
 	if height == 0 {
 		latest := tree.Version()

store/iavl/store_test.go

@@ -45,6 +45,59 @@ func newAlohaTree(t *testing.T, db dbm.DB) (*iavl.MutableTree, types.CommitID) {
 	return tree, types.CommitID{ver, hash}
 }
 
+func TestGetImmutable(t *testing.T) {
+	db := dbm.NewMemDB()
+	tree, cID := newAlohaTree(t, db)
+	store := UnsafeNewStore(tree, 10, 10)
+
+	require.True(t, tree.Set([]byte("hello"), []byte("adios")))
+	hash, ver, err := tree.SaveVersion()
+	cID = types.CommitID{ver, hash}
+	require.Nil(t, err)
+
+	_, err = store.GetImmutable(cID.Version + 1)
+	require.Error(t, err)
+
+	newStore, err := store.GetImmutable(cID.Version - 1)
+	require.NoError(t, err)
+	require.Equal(t, newStore.Get([]byte("hello")), []byte("goodbye"))
+
+	newStore, err = store.GetImmutable(cID.Version)
+	require.NoError(t, err)
+	require.Equal(t, newStore.Get([]byte("hello")), []byte("adios"))
+
+	res := newStore.Query(abci.RequestQuery{Data: []byte("hello"), Height: cID.Version, Path: "/key", Prove: true})
+	require.Equal(t, res.Value, []byte("adios"))
+	require.NotNil(t, res.Proof)
+
+	require.Panics(t, func() { newStore.Set(nil, nil) })
+	require.Panics(t, func() { newStore.Delete(nil) })
+	require.Panics(t, func() { newStore.Commit() })
+}
+
+func TestTestGetImmutableIterator(t *testing.T) {
+	db := dbm.NewMemDB()
+	tree, cID := newAlohaTree(t, db)
+	store := UnsafeNewStore(tree, 10, 10)
+
+	newStore, err := store.GetImmutable(cID.Version)
+	require.NoError(t, err)
+
+	iter := newStore.Iterator([]byte("aloha"), []byte("hellz"))
+	expected := []string{"aloha", "hello"}
+	var i int
+
+	for i = 0; iter.Valid(); iter.Next() {
+		expectedKey := expected[i]
+		key, value := iter.Key(), iter.Value()
+		require.EqualValues(t, key, expectedKey)
+		require.EqualValues(t, value, treeData[expectedKey])
+		i++
+	}
+
+	require.Equal(t, len(expected), i)
+}
+
 func TestIAVLStoreGetSetHasDelete(t *testing.T) {
 	db := dbm.NewMemDB()
 	tree, _ := newAlohaTree(t, db)

store/iavl/tree.go

@@ -0,0 +1,84 @@
+package iavl
+
+import (
+	"fmt"
+
+	"github.com/tendermint/iavl"
+)
+
+var (
+	_ Tree = (*immutableTree)(nil)
+	_ Tree = (*iavl.MutableTree)(nil)
+)
+
+type (
+	// Tree defines an interface that both mutable and immutable IAVL trees
+	// must implement. For mutable IAVL trees, the interface is directly
+	// implemented by an iavl.MutableTree. For an immutable IAVL tree, a wrapper
+	// must be made.
+	Tree interface {
+		Has(key []byte) bool
+		Get(key []byte) (index int64, value []byte)
+		Set(key, value []byte) bool
+		Remove(key []byte) ([]byte, bool)
+		SaveVersion() ([]byte, int64, error)
+		DeleteVersion(version int64) error
+		Version() int64
+		Hash() []byte
+		VersionExists(version int64) bool
+		GetVersioned(key []byte, version int64) (int64, []byte)
+		GetVersionedWithProof(key []byte, version int64) ([]byte, *iavl.RangeProof, error)
+		GetImmutable(version int64) (*iavl.ImmutableTree, error)
+	}
+
+	// immutableTree is a simple wrapper around a reference to an iavl.ImmutableTree
+	// that implements the Tree interface. It should only be used for querying
+	// and iteration, specifically at previous heights.
+	immutableTree struct {
+		*iavl.ImmutableTree
+	}
+)
+
+func (it *immutableTree) Set(_, _ []byte) bool {
+	panic("cannot call 'Set' on an immutable IAVL tree")
+}
+
+func (it *immutableTree) Remove(_ []byte) ([]byte, bool) {
+	panic("cannot call 'Remove' on an immutable IAVL tree")
+}
+
+func (it *immutableTree) SaveVersion() ([]byte, int64, error) {
+	panic("cannot call 'SaveVersion' on an immutable IAVL tree")
+}
+
+func (it *immutableTree) DeleteVersion(_ int64) error {
+	panic("cannot call 'DeleteVersion' on an immutable IAVL tree")
+}
+
+func (it *immutableTree) VersionExists(version int64) bool {
+	return it.Version() == version
+}
+
+func (it *immutableTree) GetVersioned(key []byte, version int64) (int64, []byte) {
+	if it.Version() != version {
+		return -1, nil
+	}
+
+	return it.Get(key)
+}
+
+func (it *immutableTree) GetVersionedWithProof(key []byte, version int64) ([]byte, *iavl.RangeProof, error) {
+	if it.Version() != version {
+		return nil, nil, fmt.Errorf("version mismatch on immutable IAVL tree; got: %d, expected: %d", version, it.Version())
+	}
+
+	return it.GetWithProof(key)
+}
+
+func (it *immutableTree) GetImmutable(version int64) (*iavl.ImmutableTree, error) {
+	if it.Version() != version {
+		return nil, fmt.Errorf("version mismatch on immutable IAVL tree; got: %d, expected: %d", version, it.Version())
+	}
+
+	return it.ImmutableTree, nil
+}