db: fix c and go iterators

db/c_level_db.go

@@ -3,6 +3,7 @@
 package db
 
 import (
+	"bytes"
 	"fmt"
 	"path/filepath"
 
@@ -166,7 +167,7 @@ func (db *CLevelDB) Iterator(start, end []byte) Iterator {
 	} else {
 		itr.SeekToFirst()
 	}
-	return cLevelDBIterator{
+	return &cLevelDBIterator{
 		itr:   itr,
 		start: start,
 		end:   end,
@@ -183,43 +184,58 @@ var _ Iterator = (*cLevelDBIterator)(nil)
 type cLevelDBIterator struct {
 	itr        *levigo.Iterator
 	start, end []byte
+	invalid    bool
 }
 
-func (c cLevelDBIterator) Domain() ([]byte, []byte) {
+func (c *cLevelDBIterator) Domain() ([]byte, []byte) {
 	return c.start, c.end
 }
 
-func (c cLevelDBIterator) Valid() bool {
+func (c *cLevelDBIterator) Valid() bool {
 	c.assertNoError()
-	return c.itr.Valid()
+	if c.invalid {
+		return false
+	}
+	c.invalid = !c.itr.Valid()
+	return !c.invalid
 }
 
-func (c cLevelDBIterator) Key() []byte {
-	if !c.itr.Valid() {
+func (c *cLevelDBIterator) Key() []byte {
+	if !c.Valid() {
 		panic("cLevelDBIterator Key() called when invalid")
 	}
 	return c.itr.Key()
 }
 
-func (c cLevelDBIterator) Value() []byte {
-	if !c.itr.Valid() {
+func (c *cLevelDBIterator) Value() []byte {
+	if !c.Valid() {
 		panic("cLevelDBIterator Value() called when invalid")
 	}
 	return c.itr.Value()
 }
 
-func (c cLevelDBIterator) Next() {
-	if !c.itr.Valid() {
+func (c *cLevelDBIterator) Next() {
+	if !c.Valid() {
 		panic("cLevelDBIterator Next() called when invalid")
 	}
 	c.itr.Next()
+	c.checkEndKey() // if we've exceeded the range, we're now invalid
+}
+
+// levigo has no upper bound when iterating, so need to check ourselves
+func (c *cLevelDBIterator) checkEndKey() []byte {
+	key := c.itr.Key()
+	if c.end != nil && bytes.Compare(key, c.end) > 0 {
+		c.invalid = true
+	}
+	return key
 }
 
-func (c cLevelDBIterator) Release() {
+func (c *cLevelDBIterator) Release() {
 	c.itr.Close()
 }
 
-func (c cLevelDBIterator) assertNoError() {
+func (c *cLevelDBIterator) assertNoError() {
 	if err := c.itr.GetError(); err != nil {
 		panic(err)
 	}

db/go_level_db.go

@@ -8,6 +8,7 @@ import (
 	"github.com/syndtr/goleveldb/leveldb/errors"
 	"github.com/syndtr/goleveldb/leveldb/iterator"
 	"github.com/syndtr/goleveldb/leveldb/opt"
+	"github.com/syndtr/goleveldb/leveldb/util"
 
 	. "github.com/tendermint/tmlibs/common"
 )
@@ -169,13 +170,24 @@ func (mBatch *goLevelDBBatch) Write() {
 //----------------------------------------
 // Iterator
 
-func (db *GoLevelDB) Iterator(start, end []byte) Iterator {
-	itr := db.db.NewIterator(nil, nil)
-	if len(start) > 0 {
-		itr.Seek(start)
-	} else {
-		itr.First()
+// https://godoc.org/github.com/syndtr/goleveldb/leveldb#DB.NewIterator
+// A nil Range.Start is treated as a key before all keys in the DB.
+// And a nil Range.Limit is treated as a key after all keys in the DB.
+func goLevelDBIterRange(start, end []byte) *util.Range {
+	// XXX: what if start == nil ?
+	if len(start) == 0 {
+		start = nil
+	}
+	return &util.Range{
+		Start: start,
+		Limit: end,
 	}
+}
+
+func (db *GoLevelDB) Iterator(start, end []byte) Iterator {
+	itrRange := goLevelDBIterRange(start, end)
+	itr := db.db.NewIterator(itrRange, nil)
+	itr.Seek(start) // if we don't call this the itr is never valid (?!)
 	return &goLevelDBIterator{
 		source: itr,
 		start:  start,

db/util_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 )
 
+// empty iterator for empty db
 func TestPrefixIteratorNoMatchNil(t *testing.T) {
 	for backend, _ := range backends {
 		t.Run(fmt.Sprintf("Prefix w/ backend %s", backend), func(t *testing.T) {
@@ -16,6 +17,7 @@ func TestPrefixIteratorNoMatchNil(t *testing.T) {
 	}
 }
 
+// empty iterator for db populated after iterator created
 func TestPrefixIteratorNoMatch1(t *testing.T) {
 	for backend, _ := range backends {
 		t.Run(fmt.Sprintf("Prefix w/ backend %s", backend), func(t *testing.T) {
@@ -28,24 +30,8 @@ func TestPrefixIteratorNoMatch1(t *testing.T) {
 	}
 }
 
-func TestPrefixIteratorMatch2(t *testing.T) {
-	for backend, _ := range backends {
-		t.Run(fmt.Sprintf("Prefix w/ backend %s", backend), func(t *testing.T) {
-			db := newTempDB(t, backend)
-			db.SetSync(bz("2"), bz("value_2"))
-			itr := IteratePrefix(db, []byte("2"))
-
-			checkValid(t, itr, true)
-			checkItem(t, itr, bz("2"), bz("value_2"))
-			checkNext(t, itr, false)
-
-			// Once invalid...
-			checkInvalid(t, itr)
-		})
-	}
-}
-
-func TestPrefixIteratorMatch3(t *testing.T) {
+// empty iterator for prefix starting above db entry
+func TestPrefixIteratorNoMatch2(t *testing.T) {
 	for backend, _ := range backends {
 		t.Run(fmt.Sprintf("Prefix w/ backend %s", backend), func(t *testing.T) {
 			db := newTempDB(t, backend)
@@ -58,21 +44,16 @@ func TestPrefixIteratorMatch3(t *testing.T) {
 	}
 }
 
-// Search for a/1, fail by too much Next()
-func TestPrefixIteratorMatches1N(t *testing.T) {
+// iterator with single val for db with single val, starting from that val
+func TestPrefixIteratorMatch1(t *testing.T) {
 	for backend, _ := range backends {
 		t.Run(fmt.Sprintf("Prefix w/ backend %s", backend), func(t *testing.T) {
 			db := newTempDB(t, backend)
-			db.SetSync(bz("a/1"), bz("value_1"))
-			db.SetSync(bz("a/3"), bz("value_3"))
-			itr := IteratePrefix(db, []byte("a/"))
+			db.SetSync(bz("2"), bz("value_2"))
+			itr := IteratePrefix(db, bz("2"))
 
 			checkValid(t, itr, true)
-			checkItem(t, itr, bz("a/1"), bz("value_1"))
-			checkNext(t, itr, true)
-			checkItem(t, itr, bz("a/3"), bz("value_3"))
-
-			// Bad!
+			checkItem(t, itr, bz("2"), bz("value_2"))
 			checkNext(t, itr, false)
 
 			// Once invalid...
@@ -81,38 +62,22 @@ func TestPrefixIteratorMatches1N(t *testing.T) {
 	}
 }
 
-// Search for a/2, fail by too much Next()
-func TestPrefixIteratorMatches2N(t *testing.T) {
+// iterator with prefix iterates over everything with same prefix
+func TestPrefixIteratorMatches1N(t *testing.T) {
 	for backend, _ := range backends {
 		t.Run(fmt.Sprintf("Prefix w/ backend %s", backend), func(t *testing.T) {
 			db := newTempDB(t, backend)
-			db.SetSync(bz("a/1"), bz("value_1"))
-			db.SetSync(bz("a/3"), bz("value_3"))
-			itr := IteratePrefix(db, []byte("a/"))
-
-			checkValid(t, itr, true)
-			checkItem(t, itr, bz("a/1"), bz("value_1"))
-			checkNext(t, itr, true)
-			checkValid(t, itr, true)
-			checkItem(t, itr, bz("a/3"), bz("value_3"))
-
-			// Bad!
-			checkNext(t, itr, false)
-
-			// Once invalid...
-			checkInvalid(t, itr)
-		})
-	}
-}
 
-// Search for a/3, fail by too much Next()
-func TestPrefixIteratorMatches3N(t *testing.T) {
-	for backend, _ := range backends {
-		t.Run(fmt.Sprintf("Prefix w/ backend %s", backend), func(t *testing.T) {
-			db := newTempDB(t, backend)
+			// prefixed
 			db.SetSync(bz("a/1"), bz("value_1"))
 			db.SetSync(bz("a/3"), bz("value_3"))
-			itr := IteratePrefix(db, []byte("a/"))
+
+			// not
+			db.SetSync(bz("b/3"), bz("value_3"))
+			db.SetSync(bz("a-3"), bz("value_3"))
+			db.SetSync(bz("a.3"), bz("value_3"))
+			db.SetSync(bz("abcdefg"), bz("value_3"))
+			itr := IteratePrefix(db, bz("a/"))
 
 			checkValid(t, itr, true)
 			checkItem(t, itr, bz("a/1"), bz("value_1"))
@@ -122,7 +87,7 @@ func TestPrefixIteratorMatches3N(t *testing.T) {
 			// Bad!
 			checkNext(t, itr, false)
 
-			// Once invalid...
+			//Once invalid...
 			checkInvalid(t, itr)
 		})
 	}