fix(core): avoid inspect.getsource in RunnableLambda.deps

libs/core/langchain_core/runnables/utils.py

@@ -4,13 +4,15 @@
 
 import ast
 import asyncio
+import dis
 import inspect
 import sys
 import textwrap
 
 # Cannot move to TYPE_CHECKING as Mapping and Sequence are needed at runtime by
 # RunnableConfigurableFields.
 from collections.abc import Mapping, Sequence  # noqa: TC003
+from contextlib import suppress
 from functools import lru_cache
 from inspect import signature
 from itertools import groupby
@@ -38,6 +40,7 @@
         Iterable,
     )
     from contextvars import Context
+    from types import CodeType
 
     from langchain_core.runnables.schema import StreamEvent
 
@@ -404,6 +407,63 @@ def get_lambda_source(func: Callable) -> str | None:
     return visitor.source if visitor.count == 1 else name
 
 
+@lru_cache(maxsize=256)
+def _nonlocal_access_plan(
+    code: CodeType,
+) -> tuple[tuple[str, ...], tuple[tuple[str, tuple[str, ...]], ...]]:
+    """Compute a nonlocal access plan from bytecode.
+
+    Args:
+        code: Code object to scan.
+
+    Returns:
+        A tuple ``(plain_roots, chains)``, where:
+        - plain_roots: Names loaded without any attribute access.
+        - chains: ``(root, path)`` pairs for attribute-access chains.
+    """
+    root_ops = {"LOAD_GLOBAL", "LOAD_DEREF", "LOAD_NAME"}
+    attr_ops = {"LOAD_ATTR", "LOAD_METHOD"}
+
+    plain_roots: set[str] = set()
+    chains: list[tuple[str, tuple[str, ...]]] = []
+
+    base: str | None = None
+    attrs: list[str] = []
+
+    def flush() -> None:
+        nonlocal base, attrs
+        if base is not None:
+            if attrs:
+                chains.append((base, tuple(attrs)))
+            else:
+                plain_roots.add(base)
+        base = None
+        attrs = []
+
+    for ins in dis.get_instructions(code):
+        op = ins.opname
+        if op in root_ops and isinstance(ins.argval, str):
+            flush()
+            base = ins.argval
+            continue
+        if op in attr_ops and isinstance(ins.argval, str):
+            if base is not None:
+                attrs.append(ins.argval)
+            continue
+        flush()
+
+    flush()
+
+    deduped = []
+    seen = set()
+    for c in chains:
+        if c not in seen:
+            seen.add(c)
+            deduped.append(c)
+
+    return tuple(sorted(plain_roots)), tuple(deduped)
+
+
 @lru_cache(maxsize=256)
 def get_function_nonlocals(func: Callable) -> list[Any]:
     """Get the nonlocal variables accessed by a function.
@@ -414,37 +474,83 @@ def get_function_nonlocals(func: Callable) -> list[Any]:
     Returns:
         The nonlocal variables accessed by the function.
     """
-    try:
-        code = inspect.getsource(func)
-        tree = ast.parse(textwrap.dedent(code))
-        visitor = FunctionNonLocals()
-        visitor.visit(tree)
-        values: list[Any] = []
-        closure = (
-            inspect.getclosurevars(func.__wrapped__)
-            if hasattr(func, "__wrapped__") and callable(func.__wrapped__)
-            else inspect.getclosurevars(func)
-        )
-        candidates = {**closure.globals, **closure.nonlocals}
-        for k, v in candidates.items():
-            if k in visitor.nonlocals:
-                values.append(v)
-            for kk in visitor.nonlocals:
-                if "." in kk and kk.startswith(k):
-                    vv = v
-                    for part in kk.split(".")[1:]:
-                        if vv is None:
-                            break
-                        try:
-                            vv = getattr(vv, part)
-                        except AttributeError:
-                            break
-                    else:
-                        values.append(vv)
-    except (SyntaxError, TypeError, OSError, SystemError):
+    terminal_methods = {
+        "invoke",
+        "ainvoke",
+        "batch",
+        "abatch",
+        "stream",
+        "astream",
+        "transform",
+        "atransform",
+    }
+
+    target = func
+    seen_wrapped = set()
+    while True:
+        w = getattr(target, "__wrapped__", None)
+        if not callable(w):
+            break
+        wid = id(w)
+        if wid in seen_wrapped:
+            break
+        seen_wrapped.add(wid)
+        target = w
+
+    if getattr(target, "__code__", None) is None:
+        target = getattr(target, "__func__", target)
+
+    code = getattr(target, "__code__", None)
+    if code is None:
         return []
 
-    return values
+    nonlocals_dict = {}
+    freevars = code.co_freevars
+    closure = getattr(target, "__closure__", None)
+    if closure and freevars:
+        for name, cell in zip(freevars, closure, strict=False):
+            with suppress(ValueError):
+                nonlocals_dict[name] = cell.cell_contents
+
+    globals_dict = getattr(target, "__globals__", {})
+
+    plain_roots, chains = _nonlocal_access_plan(code)
+
+    out = []
+    seen_ids = set()
+
+    def add(v: Any) -> None:
+        vid = id(v)
+        if vid not in seen_ids:
+            seen_ids.add(vid)
+            out.append(v)
+
+    def resolve_root(name: str) -> Any | None:
+        if name in nonlocals_dict:
+            return nonlocals_dict[name]
+        return globals_dict.get(name)
+
+    for name in plain_roots:
+        v = resolve_root(name)
+        if v is not None:
+            add(v)
+
+    for base, attrs in chains:
+        if not attrs or attrs[-1] not in terminal_methods:
+            continue
+        v = resolve_root(base)
+        if v is None:
+            continue
+        for a in attrs:
+            try:
+                v = getattr(v, a)
+            except Exception:
+                break
+        else:
+            if v is not None:
+                add(v)
+
+    return out
 
 
 def indent_lines_after_first(text: str, prefix: str) -> str:

libs/core/tests/unit_tests/runnables/test_utils.py

@@ -1,5 +1,6 @@
+import inspect
 from collections.abc import Callable
-from typing import Any
+from typing import Any, NoReturn
 
 import pytest
 
@@ -73,3 +74,35 @@ def my_func6(value: str) -> str:
     assert RunnableLambda(my_func3).deps == [agent]
     assert RunnableLambda(my_func4).deps == [global_agent]
     assert RunnableLambda(func).deps == [nl]
+
+
+def test_deps_does_not_call_inspect_getsource() -> None:
+    original = inspect.getsource
+    error_message = "inspect.getsource was called while computing deps"
+
+    def explode(*_args: Any, **_kwargs: Any) -> NoReturn:
+        raise AssertionError(error_message)
+
+    inspect.getsource = explode
+    try:
+        agent: RunnableLambda[str, str] = RunnableLambda(lambda x: x)
+
+        class Box:
+            def __init__(self, a: RunnableLambda[str, str]) -> None:
+                self.agent: RunnableLambda[str, str] = a
+
+        box = Box(agent)
+
+        def my_func(x: str) -> str:
+            return box.agent.invoke(x)
+
+        r: RunnableLambda[str, str] = RunnableLambda(my_func)
+        _ = r.deps
+    finally:
+        inspect.getsource = original
+
+
+def test_deps_is_cached_on_instance() -> None:
+    r = RunnableLambda(lambda x: x)
+    _ = r.deps
+    assert "deps" in r.__dict__