sequencer: fix state transition stuck on census tree nil root after restart

census/censusdb/censusdb.go

@@ -281,6 +281,75 @@ func (c *CensusDB) LoadByScopedAddress(chainID uint64, address common.Address) (
 	return c.loadCensusRef(scopedAddressToCensusID(chainID, address), scopedAddressDBPrefix(chainID, address))
 }
 
+// LoadFromPersistentTree loads a census tree directly from the persistent KV
+// storage (censusTreeDBPrefix) for the given root hash, bypassing the
+// ephemeral Pebble cache. This recovers census state after a node restart
+// when the Pebble tree on disk is empty but the KV-backed tree still holds
+// all leaves from the original Import call.
+//
+// If the census is already in the in-memory cache but its tree has no root
+// (i.e. the cached ref holds an empty Pebble tree), the cached tree is
+// replaced with the persistent KV-backed tree.
+func (c *CensusDB) LoadFromPersistentTree(root types.HexBytes) (*CensusRef, error) {
+	censusID := rootToCensusID(root)
+
+	// Check in-memory cache, but only return the cached ref if its tree has a
+	// valid root. If the cached tree is empty (happens after restart when the
+	// Pebble store has been wiped), fall through and reload from the KV backend.
+	c.mu.RLock()
+	if ref, exists := c.loadedCensus[censusID]; exists {
+		if _, ok := ref.tree.Root(); ok {
+			c.mu.RUnlock()
+			return ref, nil
+		}
+	}
+	c.mu.RUnlock()
+
+	// Open the persistent KV-backed tree.
+	treeDB := prefixeddb.NewPrefixedDatabase(c.db, censusTreeDBPrefix(censusID))
+	tree, err := census.NewCensusIMT(treeDB, censusHasher)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open persistent census tree: %w", err)
+	}
+	treeRoot, ok := tree.Root()
+	if !ok {
+		return nil, fmt.Errorf("%w: persistent tree has no root for census root %s",
+			ErrCensusNotFound, root.String())
+	}
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	// Re-check under write lock.
+	if ref, exists := c.loadedCensus[censusID]; exists {
+		if _, ok := ref.tree.Root(); ok {
+			return ref, nil
+		}
+		// Cached ref has an empty tree — replace it with the persistent tree.
+		ref.SetTree(tree)
+		ref.currentRoot = treeRoot.Bytes()
+		ref.LastUsed = time.Now()
+		return ref, nil
+	}
+
+	ref := &CensusRef{
+		ID:                censusID,
+		HashType:          censusHasherName,
+		LastUsed:          time.Now(),
+		updateRootRequest: c.updateRootChan,
+	}
+	ref.currentRoot = treeRoot.Bytes()
+	ref.SetTree(tree)
+
+	c.loadedCensus[censusID] = ref
+	rk := rootKey(ref.currentRoot)
+	if _, exists := c.rootIndex[rk]; !exists {
+		c.rootIndex[rk] = censusID
+	}
+
+	return ref, nil
+}
+
 // loadCensusRef loads a census reference from memory or persistent DB using a
 // double‑check. It takes the censusID and the key to use.
 func (c *CensusDB) loadCensusRef(censusID uuid.UUID, key types.HexBytes) (*CensusRef, error) {

census/graphql.go

@@ -248,7 +248,7 @@ func queryEvents(
 			if err != nil {
 				return nil, fmt.Errorf("error creating request: %v", err)
 			}
-			req.Header.Set("Content-Type", "application/json")
+			req.Header.Set(contentTypeHeader, "application/json")
 			res, err := client.Do(req)
 			if err != nil {
 				return nil, fmt.Errorf("error executing request: %v", err)

census/importer_test.go

@@ -14,6 +14,8 @@ import (
 	"github.com/vocdoni/davinci-node/types"
 )
 
+const testCensusURI = "https://example.invalid/dump"
+
 func testNewCensusDB(c *qt.C) *censusdb.CensusDB {
 	c.Helper()
 	internalDB, err := metadb.New(db.TypeInMem, "")
@@ -73,7 +75,7 @@ func TestCensusImporter(t *testing.T) {
 			importer := NewCensusImporter(nil)
 			_, err := importer.ImportCensus(c.Context(), 0, &types.Census{
 				CensusOrigin: types.CensusOriginUnknown,
-				CensusURI:    "https://example.invalid/dump",
+				CensusURI:    testCensusURI,
 				CensusRoot:   types.HexBytes{0x01},
 			}, 0)
 			c.Assert(err, qt.Not(qt.IsNil))
@@ -104,13 +106,13 @@ func TestCensusImporter(t *testing.T) {
 				validFn: func(string) bool { return false },
 			}
 			plugin2 := &testImporterPlugin{
-				validFn: func(uri string) bool { return uri == "https://example.invalid/dump" },
+				validFn: func(uri string) bool { return uri == testCensusURI },
 			}
 
 			importer := NewCensusImporter(stg, plugin1, plugin2)
 			census := &types.Census{
 				CensusOrigin: types.CensusOriginMerkleTreeOffchainStaticV1,
-				CensusURI:    "https://example.invalid/dump",
+				CensusURI:    testCensusURI,
 				CensusRoot:   types.HexBytes{0xaa, 0xbb},
 			}
 
@@ -136,7 +138,7 @@ func TestCensusImporter(t *testing.T) {
 			importer := NewCensusImporter(stg, plugin)
 			_, err := importer.ImportCensus(c.Context(), 0, &types.Census{
 				CensusOrigin: types.CensusOriginMerkleTreeOffchainDynamicV1,
-				CensusURI:    "https://example.invalid/dump",
+				CensusURI:    testCensusURI,
 				CensusRoot:   types.HexBytes{0x01},
 			}, 0)
 			c.Assert(err, qt.ErrorIs, sentinelErr)
@@ -150,7 +152,7 @@ func TestCensusImporter(t *testing.T) {
 			importer := NewCensusImporter(stg, plugin)
 			_, err := importer.ImportCensus(c.Context(), 0, &types.Census{
 				CensusOrigin: types.CensusOriginMerkleTreeOffchainStaticV1,
-				CensusURI:    "https://example.invalid/dump",
+				CensusURI:    testCensusURI,
 				CensusRoot:   types.HexBytes{0x01},
 			}, 0)
 			c.Assert(err, qt.Not(qt.IsNil))

census/json.go

@@ -29,6 +29,8 @@ const (
 	UnknownJSON
 )
 
+const contentTypeHeader = "Content-Type"
+
 // String returns the string representation of the JSONFormat.
 func (format JSONFormat) String() string {
 	switch format {
@@ -127,7 +129,7 @@ func requestRawDump(ctx context.Context, targetURL string) (*http.Response, erro
 // cannot be determined, it returns UnknownJSON.
 func jsonReader(res *http.Response) (io.Reader, JSONFormat, error) {
 	// Check Content-Type header first
-	contentType := strings.ToLower(res.Header.Get("Content-Type"))
+	contentType := strings.ToLower(res.Header.Get(contentTypeHeader))
 
 	if strings.Contains(contentType, "ndjson") || strings.Contains(contentType, "jsonl") {
 		return res.Body, JSONL, nil

census/json_test.go

@@ -18,6 +18,11 @@ import (
 	leancensus "github.com/vocdoni/lean-imt-go/census"
 )
 
+const (
+	testCensusURI2        = "https://example.invalid/dump"
+	testContentTypeNDJSON = "application/x-ndjson"
+)
+
 type testErrReader struct {
 	err error
 }
@@ -125,7 +130,7 @@ func TestRequestRawDump(t *testing.T) {
 			c.Assert(r.Header.Get("Accept"), qt.Equals, "application/x-ndjson, application/json;q=0.9, */*;q=0.1")
 			return &http.Response{
 				StatusCode: http.StatusOK,
-				Header:     http.Header{"Content-Type": []string{"application/x-ndjson"}},
+				Header:     http.Header{contentTypeHeader: []string{testContentTypeNDJSON}},
 				Body:       io.NopCloser(strings.NewReader(`{"ok":true}` + "\n")),
 				Request:    r,
 			}, nil
@@ -192,7 +197,7 @@ func TestJSONReader(t *testing.T) {
 	c.Run("ContentTypeJSONL", func(c *qt.C) {
 		const body = `{"a":1}` + "\n"
 		res := &http.Response{
-			Header: http.Header{"Content-Type": []string{"application/x-ndjson"}},
+			Header: http.Header{contentTypeHeader: []string{testContentTypeNDJSON}},
 			Body:   io.NopCloser(strings.NewReader(body)),
 		}
 
@@ -208,7 +213,7 @@ func TestJSONReader(t *testing.T) {
 	c.Run("ContentTypeJSONArray", func(c *qt.C) {
 		const body = `[{"a":1}]`
 		res := &http.Response{
-			Header: http.Header{"Content-Type": []string{"application/json; charset=utf-8"}},
+			Header: http.Header{contentTypeHeader: []string{"application/json; charset=utf-8"}},
 			Body:   io.NopCloser(strings.NewReader(body)),
 		}
 
@@ -352,7 +357,7 @@ func TestJSONDownloadAndImportCensus(t *testing.T) {
 		http.DefaultTransport = roundTripperFunc(func(r *http.Request) (*http.Response, error) {
 			return &http.Response{
 				StatusCode: http.StatusOK,
-				Header:     http.Header{"Content-Type": []string{"application/json"}},
+				Header:     http.Header{contentTypeHeader: []string{"application/json"}},
 				Body: &testReadCloser{
 					Reader:   bytes.NewReader(dumpJSON),
 					closeErr: fmt.Errorf("close error"),
@@ -382,7 +387,7 @@ func TestJSONDownloadAndImportCensus(t *testing.T) {
 		c.Cleanup(func() { http.DefaultTransport = oldTransport })
 
 		_, err := ji.ImportCensus(c.Context(), censusDB, 0, &types.Census{
-			CensusURI:  "https://example.invalid/dump",
+			CensusURI:  testCensusURI2,
 			CensusRoot: expectedRoot,
 		}, 0)
 		c.Assert(err, qt.Not(qt.IsNil))
@@ -402,7 +407,7 @@ func TestJSONDownloadAndImportCensus(t *testing.T) {
 		c.Cleanup(func() { http.DefaultTransport = oldTransport })
 
 		_, err := ji.ImportCensus(c.Context(), censusDB, 0, &types.Census{
-			CensusURI:  "https://example.invalid/dump",
+			CensusURI:  testCensusURI2,
 			CensusRoot: expectedRoot,
 		}, 0)
 		c.Assert(err, qt.Not(qt.IsNil))
@@ -414,7 +419,7 @@ func TestJSONDownloadAndImportCensus(t *testing.T) {
 		http.DefaultTransport = roundTripperFunc(func(r *http.Request) (*http.Response, error) {
 			return &http.Response{
 				StatusCode: http.StatusOK,
-				Header:     http.Header{"Content-Type": []string{"application/x-ndjson"}},
+				Header:     http.Header{contentTypeHeader: []string{testContentTypeNDJSON}},
 				Body:       io.NopCloser(strings.NewReader("not json\n")),
 				Request:    r,
 			}, nil
@@ -435,7 +440,7 @@ func TestJSONDownloadAndImportCensus(t *testing.T) {
 		http.DefaultTransport = roundTripperFunc(func(r *http.Request) (*http.Response, error) {
 			return &http.Response{
 				StatusCode: http.StatusOK,
-				Header:     http.Header{"Content-Type": []string{"application/json"}},
+				Header:     http.Header{contentTypeHeader: []string{"application/json"}},
 				Body:       io.NopCloser(bytes.NewReader(dumpJSON)),
 				Request:    r,
 			}, nil

census/test/graphql.go

@@ -13,11 +13,16 @@ import (
 	"github.com/vocdoni/davinci-node/types"
 )
 
+const (
+	testAccountID1 = "0xdeb8699659be5d41a0e57e179d6cb42e00b9200c"
+	testAccountID2 = "0xb1f05b11ba3d892edd00f2e7689779e2b8841827"
+)
+
 var (
 	DefaultExpectedRoot  = types.HexStringToHexBytesMustUnmarshal("0x0b3600e19a4f5017dea4f91f03d8aa0dd6f4c797795e7a5aa542e81b2c5a9485")
 	DefaultGraphQLEvents = []TestWeightChangeEvent{
 		{
-			AccountID:      "0xdeb8699659be5d41a0e57e179d6cb42e00b9200c",
+			AccountID:      testAccountID1,
 			PreviousWeight: "0",
 			NewWeight:      "1",
 		},
@@ -27,7 +32,7 @@ var (
 			NewWeight:      "1",
 		},
 		{
-			AccountID:      "0xb1f05b11ba3d892edd00f2e7689779e2b8841827",
+			AccountID:      testAccountID2,
 			PreviousWeight: "0",
 			NewWeight:      "1",
 		},
@@ -47,12 +52,12 @@ var (
 			NewWeight:      "0",
 		},
 		{
-			AccountID:      "0xdeb8699659be5d41a0e57e179d6cb42e00b9200c",
+			AccountID:      testAccountID1,
 			PreviousWeight: "1",
 			NewWeight:      "0",
 		},
 		{
-			AccountID:      "0xb1f05b11ba3d892edd00f2e7689779e2b8841827",
+			AccountID:      testAccountID2,
 			PreviousWeight: "1",
 			NewWeight:      "2",
 		},
@@ -62,12 +67,12 @@ var (
 			NewWeight:      "1",
 		},
 		{
-			AccountID:      "0xb1f05b11ba3d892edd00f2e7689779e2b8841827",
+			AccountID:      testAccountID2,
 			PreviousWeight: "2",
 			NewWeight:      "1",
 		},
 		{
-			AccountID:      "0xdeb8699659be5d41a0e57e179d6cb42e00b9200c",
+			AccountID:      testAccountID1,
 			PreviousWeight: "0",
 			NewWeight:      "1",
 		},

circuits/test/statetransition/statetransition_test.go

@@ -37,11 +37,14 @@ import (
 	"github.com/vocdoni/davinci-node/util"
 )
 
-const falseString = "false"
+const (
+	falseString    = "false"
+	testTimeFormat = "15:04:05"
+)
 
 func TestMain(m *testing.M) {
 	// enable log to see nbConstraints
-	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: "15:04:05"}).With().Timestamp().Logger())
+	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: testTimeFormat}).With().Timestamp().Logger())
 	m.Run()
 }
 
@@ -50,7 +53,7 @@ func testCircuitCompile(t *testing.T, c frontend.Circuit) {
 		t.Skip("skipping circuit tests...")
 	}
 	// enable log to see nbConstraints
-	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: "15:04:05"}).With().Timestamp().Logger())
+	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: testTimeFormat}).With().Timestamp().Logger())
 	if _, err := frontend.Compile(params.StateTransitionCurve.ScalarField(), r1cs.NewBuilder, c); err != nil {
 		panic(err)
 	}
@@ -69,7 +72,7 @@ func testCircuitProve(t *testing.T, circuit, assignment frontend.Circuit) {
 }
 
 func TestStateTransitionCircuit(t *testing.T) {
-	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: "15:04:05"}).With().Timestamp().Logger())
+	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: testTimeFormat}).With().Timestamp().Logger())
 	if os.Getenv("RUN_CIRCUIT_TESTS") == "" || os.Getenv("RUN_CIRCUIT_TESTS") == falseString {
 		t.Skip("skipping circuit tests...")
 	}
@@ -87,7 +90,7 @@ func TestStateTransitionCircuit(t *testing.T) {
 }
 
 func TestStateTransitionFullProvingCircuit(t *testing.T) {
-	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: "15:04:05"}).With().Timestamp().Logger())
+	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: testTimeFormat}).With().Timestamp().Logger())
 	if os.Getenv("RUN_CIRCUIT_TESTS") == "" || os.Getenv("RUN_CIRCUIT_TESTS") == falseString {
 		t.Skip("skipping circuit tests...")
 	}

circuits/test/voteverifier/vote_verifier_test.go

@@ -21,8 +21,10 @@ import (
 	"github.com/vocdoni/davinci-node/types"
 )
 
+const testTimeFormat = "15:04:05"
+
 func TestVerifyMerkletreeVoteCircuit(t *testing.T) {
-	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: "15:04:05"}).With().Timestamp().Logger())
+	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: testTimeFormat}).With().Timestamp().Logger())
 	c := qt.New(t)
 	// Generate a deterministic voter account for reproducible test data.
 	s, err := ballottest.GenDeterministicECDSAaccountForTest(0)
@@ -45,7 +47,7 @@ func TestVerifyMerkletreeVoteCircuit(t *testing.T) {
 }
 
 func TestVerifyCSPVoteCircuit(t *testing.T) {
-	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: "15:04:05"}).With().Timestamp().Logger())
+	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: testTimeFormat}).With().Timestamp().Logger())
 	c := qt.New(t)
 	// Generate a deterministic voter account for reproducible test data.
 	s, err := ballottest.GenDeterministicECDSAaccountForTest(0)
@@ -81,7 +83,7 @@ func TestVerifyNoValidVoteCircuit(t *testing.T) {
 }
 
 func TestVerifyMultipleVotesCircuit(t *testing.T) {
-	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: "15:04:05"}).With().Timestamp().Logger())
+	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: testTimeFormat}).With().Timestamp().Logger())
 	if os.Getenv("RUN_CIRCUIT_TESTS") == "" || os.Getenv("RUN_CIRCUIT_TESTS") == "false" {
 		t.Skip("skipping circuit tests...")
 	}
@@ -109,7 +111,7 @@ func TestCompileAndPrintConstraints(t *testing.T) {
 	if os.Getenv("RUN_CIRCUIT_TESTS") == "" || os.Getenv("RUN_CIRCUIT_TESTS") == "false" {
 		t.Skip("skipping circuit tests...")
 	}
-	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: "15:04:05"}).With().Timestamp().Logger())
+	logger.Set(zerolog.New(zerolog.ConsoleWriter{Out: os.Stdout, TimeFormat: testTimeFormat}).With().Timestamp().Logger())
 	c := qt.New(t)
 	// generate vote verifier circuit and inputs with deterministic ProcessID
 	vvPlaceholder, err := voteverifier.DummyPlaceholder()