OPIK-672 [SDK] Fix cyclic reference/recursion issue in json_encoder (#…

…964)

* OPIK-672 [SDK] Fix cyclic reference/recursion issue in json_encoder

* avoid infinite recursion in cyclic structures

sdks/python/src/opik/jsonable_encoder.py

@@ -1,12 +1,11 @@
-import logging
 import dataclasses
 import datetime as dt
-
-from typing import Callable, Any, Type, Set, Tuple
-
+import logging
 from enum import Enum
 from pathlib import PurePath
 from types import GeneratorType
+from typing import Any, Callable, Optional, Set, Tuple, Type
+
 import pydantic
 
 import opik.rest_api.core.datetime_utils as datetime_utils
@@ -25,18 +24,29 @@ def register_encoder_extension(obj_type: Type, encoder: Callable[[Any], Any]) ->
     _ENCODER_EXTENSIONS.add((obj_type, encoder))
 
 
-def jsonable_encoder(obj: Any) -> Any:
+def jsonable_encoder(obj: Any, seen: Optional[Set[int]] = None) -> Any:
     """
     This is a modified version of the serializer generated by Fern in rest_api.core.jsonable_encoder.
     The code is simplified to serialize complex objects into a textual representation.
+    It also handles cyclic references to avoid infinite recursion.
     """
+    if seen is None:
+        seen = set()
+
+    if hasattr(obj, "__dict__"):
+        obj_id = id(obj)
+        if obj_id in seen:
+            LOGGER.debug(f"Found cyclic reference to {type(obj).__name__} id={obj_id}")
+            return f"<Cyclic reference to {type(obj).__name__} id={obj_id}>"
+        seen.add(obj_id)
+
     try:
         if dataclasses.is_dataclass(obj) or isinstance(obj, pydantic.BaseModel):
             obj_dict = obj.__dict__
-            return jsonable_encoder(obj_dict)
+            return jsonable_encoder(obj_dict, seen)
 
         if isinstance(obj, Enum):
-            return jsonable_encoder(obj.value)
+            return jsonable_encoder(obj.value, seen)
         if isinstance(obj, PurePath):
             return str(obj)
         if isinstance(obj, (str, int, float, type(None))):
@@ -50,26 +60,33 @@ def jsonable_encoder(obj: Any) -> Any:
             allowed_keys = set(obj.keys())
             for key, value in obj.items():
                 if key in allowed_keys:
-                    encoded_key = jsonable_encoder(key)
-                    encoded_value = jsonable_encoder(value)
+                    encoded_key = jsonable_encoder(key, seen)
+                    encoded_value = jsonable_encoder(value, seen)
                     encoded_dict[encoded_key] = encoded_value
             return encoded_dict
         if isinstance(obj, (list, set, frozenset, GeneratorType, tuple)):
             encoded_list = []
             for item in obj:
-                encoded_list.append(jsonable_encoder(item))
+                encoded_list.append(jsonable_encoder(item, seen))
             return encoded_list
 
         for type_, encoder in _ENCODER_EXTENSIONS:
             if isinstance(obj, type_):
-                return jsonable_encoder(encoder(obj))
+                return jsonable_encoder(encoder(obj), seen)
 
         if np is not None and isinstance(obj, np.ndarray):
-            return jsonable_encoder(obj.tolist())
+            return jsonable_encoder(obj.tolist(), seen)
 
     except Exception:
         LOGGER.debug("Failed to serialize object.", exc_info=True)
 
+    finally:
+        # Once done encoding this object, remove from `seen`,
+        # so the same object can appear again at a sibling branch.
+        if hasattr(obj, "__dict__"):
+            obj_id = id(obj)
+            seen.remove(obj_id)
+
     data = str(obj)
 
     return data

sdks/python/tests/unit/message_processing/test_jsonable_encoder.py

@@ -1,14 +1,83 @@
-from typing import Any
+import dataclasses
 from datetime import date, datetime, timezone
 from threading import Lock
+from typing import Any, Optional
 
 import numpy as np
 import pytest
-import dataclasses
 
 import opik.jsonable_encoder as jsonable_encoder
 
 
+@dataclasses.dataclass
+class Node:
+    value: int
+    child: Optional["Node"] = None
+
+
+def test_jsonable_encoder__cyclic_reference():
+    """
+    Test that the encoder detects cyclic references and does not infinitely recurse.
+    """
+    # Create a simple two-node cycle: A -> B -> A
+    node_a = Node(value=1)
+    node_b = Node(value=2)
+    node_a.child = node_b
+    node_b.child = node_a
+
+    encoded = jsonable_encoder.jsonable_encoder(node_a)
+    # The exact format of the cycle marker can vary; we check that:
+    # 1. We get some structure for node_a (like a dict).
+    # 2. Inside node_a, there's a reference to node_b (a dict).
+    # 3. Inside node_b, there's a "cyclic reference" marker instead of a full node_a object.
+    print("=" * 150)
+    print(encoded)
+    assert isinstance(encoded, dict)
+    assert "value" in encoded
+    assert "child" in encoded
+
+    # node_a.child (which is node_b) should be a dict
+    assert isinstance(encoded["child"], dict)
+    assert "value" in encoded["child"]
+    assert "child" in encoded["child"]
+
+    # node_b.child should be the cycle marker
+    cycle_marker = encoded["child"]["child"]
+    print("=" * 150)
+    print(cycle_marker)
+    assert isinstance(
+        cycle_marker, str
+    ), "Expected a string marker for cyclic reference"
+    assert (
+        "<Cyclic reference to " in cycle_marker
+    ), "Should contain 'Cyclic reference' text"
+
+
+def test_jsonable_encoder__repeated_objects_in_list():
+    """
+    Test that the encoder handles a list of the same object repeated multiple times
+    without marking it as a cycle (because it isn't a cycle—just repeated references).
+    """
+    node = Node(value=42)
+
+    # Put the same node object in a list multiple times
+    repeated_list = [node, node, node]
+
+    encoded = jsonable_encoder.jsonable_encoder(repeated_list)
+    # We expect a list of three items, each being a dict with `value` = 42, `child` = None
+    assert isinstance(encoded, list)
+    assert len(encoded) == 3
+
+    for item in encoded:
+        assert isinstance(item, dict)
+        assert item.get("value") == 42
+        assert item.get("child") is None
+
+    # They are distinct dictionary objects, but there is no cycle reference marker
+    # because there's no actual cycle. It's just repeated references of the same object.
+    assert all("Cyclic reference" not in str(item) for item in encoded)
+
+
 @pytest.mark.parametrize(
     "obj",
     [