.github/workflows/test.yml

@@ -0,0 +1,23 @@
+name: Test
+
+on:
+  pull_request:
+    branches: '*'
+  push:
+    branches:
+      - main
+
+jobs:
+  test:
+    name: Run unit tests
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v3
+        with:
+          go-version-file: go.mod
+          check-latest: true
+      - name: Run unit tests
+        run: |
+          go test -v -p 1 ./...
+          go test -v ./tracker -count 20

go.mod

@@ -1,6 +1,6 @@
 module github.com/cerc-io/eth-iterator-utils
 
-go 1.19
+go 1.21
 
 require (
 	github.com/cerc-io/eth-testing v0.4.0

tracker/tracker.go

@@ -189,7 +189,7 @@ func (tr *TrackerImpl) Restore(makeIterator iter.IteratorConstructor) (
 			}
 		}
 
-		// force the lower bound path to an even length (required by geth API/HexToKeyBytes)
+		// force the lower bound path to an even length (required by NodeIterator constructor)
 		if len(recoveredPath)&1 == 1 {
 			// to avoid skipped nodes, we must rewind by one index
 			recoveredPath = rewindPath(recoveredPath)
@@ -246,6 +246,7 @@ func (it *Iterator) Next(descend bool) bool {
 	return ret
 }
 
+// Bounds returns the bounds of the underlying PrefixBoundIterator, if any
 func (it *Iterator) Bounds() ([]byte, []byte) {
 	if impl, ok := it.NodeIterator.(*iter.PrefixBoundIterator); ok {
 		return impl.Bounds()
@@ -253,20 +254,21 @@ func (it *Iterator) Bounds() ([]byte, []byte) {
 	return nil, nil
 }
 
-// Rewinds to the path of the previous (pre-order) node:
+// Returns the path, rewound to the previous (pre-order) node:
+// If path is the root (empty) or a leaf path, it's returned.
 // If the last byte of the path is zero, pops it (e.g. [1 0] => [1]).
 // Otherwise, decrements it and pads with 0xF to 64 bytes (e.g. [1] => [0 f f f ...]).
 // The passed slice is not modified.
 func rewindPath(path []byte) []byte {
-	if len(path) == 0 {
+	if len(path) == 0 || path[len(path)-1] == 0x10 {
 		return path
 	}
 	if path[len(path)-1] == 0 {
 		return path[:len(path)-1]
 	}
-	path[len(path)-1]--
 	padded := make([]byte, 64)
 	i := copy(padded, path)
+	padded[len(path)-1]--
 	for ; i < len(padded); i++ {
 		padded[i] = 0xf
 	}

tracker/tracker_test.go

@@ -25,7 +25,6 @@ func TestTracker(t *testing.T) {
 		tr := tracker.New(recoveryFile, NumIters)
 		defer tr.CloseAndSave()
 
-		var prevPath []byte
 		count := 0
 		nodeit, err := tree.NodeIterator(nil)
 		if err != nil {
@@ -33,9 +32,9 @@ func TestTracker(t *testing.T) {
 		}
 		for it := tr.Tracked(nodeit); it.Next(true); {
 			if count == interrupt {
-				return prevPath // tracker rewinds one node to prevent gaps
+				t.Logf("interrupting at: i=%d path=%v", count, it.Path())
+				return it.Path()
 			}
-			prevPath = it.Path()
 			count++
 		}
 		return nil
@@ -58,9 +57,19 @@ func TestTracker(t *testing.T) {
 	if uint(len(its)) != NumIters {
 		t.Fatalf("expected to restore %d iterators, got %d", NumIters, len(its))
 	}
+	if !its[0].Next(true) {
+		t.Fatal("iterator ends prematurely after restore")
+	}
+	if !bytes.Equal(failedAt, its[0].Path()) {
+		// Due to the constraint that NodeIterator can only be initialized with an even-length path,
+		// we sometimes rewind an extra node when restoring (e.g. [1 2 0] => [1 2]).
+		if !its[0].Next(true) {
+			t.Fatal("iterator ends prematurely after restore")
+		}
 		if !bytes.Equal(failedAt, its[0].Path()) {
 			t.Fatalf("iterator restored to wrong position: expected %v, got %v", failedAt, its[0].Path())
 		}
+	}
 
 	if fileExists(recoveryFile) {
 		t.Fatal("recovery file wasn't removed")