iterator fixes
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@ -14,13 +14,15 @@ type symmDiffIterator struct {
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eqPathIndex int // Count index of last pair of equal paths, to detect an updated key
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}
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// NewDifferenceIterator constructs a trie.NodeIterator that iterates over the exclusive elements in b that
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// are not in a. Returns the iterator, and a pointer to an integer recording the number
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// of nodes seen.
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// NewSymmetricDifferenceIterator constructs a trie.NodeIterator that iterates over the symmetric difference
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// of elements in a and b, i.e., the elements in a that are not in b, and vice versa.
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// Returns the iterator, and a pointer to an integer recording the number of nodes seen.
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func NewSymmetricDifferenceIterator(a, b trie.NodeIterator) (*symmDiffIterator, *int) {
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it := &symmDiffIterator{
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a: iterState{a, true},
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b: iterState{b, true},
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// common paths are detected by a distance <=1 from this index, so put it out of reach
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eqPathIndex: -2,
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}
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return it, &it.count
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}
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@ -91,9 +93,15 @@ func (it *symmDiffIterator) AddResolver(resolver trie.NodeResolver) {
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}
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func (it *symmDiffIterator) Next(bool) bool {
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// NodeIterators start in a "pre-valid" state, so you have to call Next before they point to a
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// valid node. This delays advancing the sub-iterators until they are so initialized by seek.
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if it.count != 0 {
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// NodeIterators start in a "pre-valid" state, so the first Next advances to a valid node.
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if it.count == 0 {
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if it.a.Next(true) {
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it.count++
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}
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if it.b.Next(true) {
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it.count++
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}
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} else {
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if it.curr().Next(true) {
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it.count++
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}
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@ -120,7 +128,7 @@ func (it *symmDiffIterator) seek() {
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cmp := bytes.Compare(it.a.Path(), it.b.Path())
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if cmp == 0 {
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it.eqPathIndex = it.count
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cmp = compareValues(&it.a, &it.b)
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cmp = compareNodes(&it.a, &it.b)
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}
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switch cmp {
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case -1:
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@ -147,8 +155,10 @@ func (it *symmDiffIterator) Error() error {
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return it.b.Error()
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}
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// Compares nodes with equal paths by value
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func compareValues(a, b trie.NodeIterator) int {
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func compareNodes(a, b trie.NodeIterator) int {
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// if cmp := bytes.Compare(a.Path(), b.Path()); cmp != 0 {
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// return cmp
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// }
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if a.Leaf() && !b.Leaf() {
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return -1
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} else if b.Leaf() && !a.Leaf() {
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@ -14,13 +14,13 @@ type kvs struct{ k, v string }
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var (
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testdata1 = []kvs{
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{"bar", "b"},
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{"barb", "ba"},
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{"bard", "bc"},
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{"bars", "bb"},
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{"bar", "b"},
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{"fab", "z"},
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{"foo", "a"},
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{"food", "ab"},
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{"foo", "a"},
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}
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testdata2 = []kvs{
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@ -38,22 +38,30 @@ var (
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func TestSymmetricDifferenceIterator(t *testing.T) {
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t.Run("with no difference", func(t *testing.T) {
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db := trie.NewDatabase(rawdb.NewMemoryDatabase())
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tree := trie.NewEmpty(db)
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di, count := utils.NewSymmetricDifferenceIterator(tree.NodeIterator(nil), tree.NodeIterator(nil))
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triea := trie.NewEmpty(db)
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di, count := utils.NewSymmetricDifferenceIterator(triea.NodeIterator(nil), triea.NodeIterator(nil))
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for di.Next(true) {
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t.Errorf("iterator should not yield any elements")
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}
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assert.Equal(t, 0, *count)
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tree.MustUpdate([]byte("foo"), []byte("bar"))
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di, count = utils.NewSymmetricDifferenceIterator(tree.NodeIterator(nil), tree.NodeIterator(nil))
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triea.MustUpdate([]byte("foo"), []byte("bar"))
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di, count = utils.NewSymmetricDifferenceIterator(triea.NodeIterator(nil), triea.NodeIterator(nil))
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for di.Next(true) {
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t.Errorf("iterator should not yield any elements")
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}
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assert.Equal(t, 4, *count)
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trieb := trie.NewEmpty(db)
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di, count = utils.NewSymmetricDifferenceIterator(triea.NodeIterator([]byte("food")), trieb.NodeIterator(nil))
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for di.Next(true) {
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t.Errorf("iterator should not yield any elements")
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t.Logf("%s", di.LeafKey())
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}
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assert.Equal(t, 0, *count)
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})
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t.Run("with one difference", func(t *testing.T) {
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t.Run("small difference", func(t *testing.T) {
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dba := trie.NewDatabase(rawdb.NewMemoryDatabase())
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triea := trie.NewEmpty(dba)
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@ -62,14 +70,31 @@ func TestSymmetricDifferenceIterator(t *testing.T) {
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trieb.MustUpdate([]byte("foo"), []byte("bar"))
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di, count := utils.NewSymmetricDifferenceIterator(triea.NodeIterator(nil), trieb.NodeIterator(nil))
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leaves := 0
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for di.Next(true) {
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if di.Leaf() {
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assert.Equal(t, []byte("foo"), di.LeafKey())
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assert.Equal(t, []byte("bar"), di.LeafBlob())
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assert.False(t, di.CommonPath())
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assert.Equal(t, "foo", string(di.LeafKey()))
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assert.Equal(t, "bar", string(di.LeafBlob()))
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leaves++
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}
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}
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assert.Equal(t, 1, leaves)
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assert.Equal(t, 2, *count)
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trieb.MustUpdate([]byte("quux"), []byte("bars"))
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di, count = utils.NewSymmetricDifferenceIterator(triea.NodeIterator(nil), trieb.NodeIterator([]byte("quux")))
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leaves = 0
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for di.Next(true) {
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if di.Leaf() {
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assert.False(t, di.CommonPath())
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assert.Equal(t, "quux", string(di.LeafKey()))
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assert.Equal(t, "bars", string(di.LeafBlob()))
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leaves++
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}
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}
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assert.Equal(t, 1, leaves)
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assert.Equal(t, 1, *count)
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})
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dba := trie.NewDatabase(rawdb.NewMemoryDatabase())
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