langgraph/libs/scheduler-kafka/tests/test_push.py

import operator
from typing import (
    Annotated,
    Literal,
    Union,
)

import pytest
from aiokafka import AIOKafkaProducer

from langgraph.checkpoint.base import BaseCheckpointSaver
from langgraph.constants import FF_SEND_V2, START
from langgraph.errors import NodeInterrupt
from langgraph.graph.state import CompiledStateGraph, StateGraph
from langgraph.scheduler.kafka import serde
from langgraph.scheduler.kafka.types import MessageToOrchestrator, Topics
from langgraph.types import Command, Send
from tests.any import AnyDict
from tests.drain import drain_topics_async

pytestmark = pytest.mark.anyio


def mk_push_graph(
    checkpointer: BaseCheckpointSaver,
) -> CompiledStateGraph:
    # copied from test_send_dedupe_on_resume

    class InterruptOnce:
        ticks: int = 0

        def __call__(self, state):
            self.ticks += 1
            if self.ticks == 1:
                raise NodeInterrupt("Bahh")
            return ["|".join(("flaky", str(state)))]

    class Node:
        def __init__(self, name: str):
            self.name = name
            self.ticks = 0
            self.__name__ = name

        def __call__(self, state):
            self.ticks += 1
            update = (
                [self.name]
                if isinstance(state, list)
                else ["|".join((self.name, str(state)))]
            )
            if isinstance(state, Command):
                return state.copy(update=update)
            else:
                return update

    def send_for_fun(state):
        return [
            Send("2", Command(goto=Send("2", 3))),
            Send("2", Command(goto=Send("flaky", 4))),
            "3.1",
        ]

    def route_to_three(state) -> Literal["3"]:
        return "3"

    builder = StateGraph(Annotated[list, operator.add])
    builder.add_node(Node("1"))
    builder.add_node(Node("2"))
    builder.add_node(Node("3"))
    builder.add_node(Node("3.1"))
    builder.add_node("flaky", InterruptOnce())
    builder.add_edge(START, "1")
    builder.add_conditional_edges("1", send_for_fun)
    builder.add_conditional_edges("2", route_to_three)

    return builder.compile(checkpointer=checkpointer)


async def test_push_graph(topics: Topics, acheckpointer: BaseCheckpointSaver) -> None:
    if not FF_SEND_V2:
        pytest.skip("Test requires FF_SEND_V2")

    input = ["0"]
    config = {"configurable": {"thread_id": "1"}}
    graph = mk_push_graph(acheckpointer)
    graph_compare = mk_push_graph(acheckpointer)

    # start a new run
    async with AIOKafkaProducer(value_serializer=serde.dumps) as producer:
        await producer.send_and_wait(
            topics.orchestrator,
            MessageToOrchestrator(input=input, config=config),
        )

    # drain topics
    orch_msgs, exec_msgs = await drain_topics_async(topics, graph)

    # check state
    state = await graph.aget_state(config)
    assert all(not t.error for t in state.tasks)
    assert state.next == ("flaky",)
    assert (
        state.values
        == await graph_compare.ainvoke(input, {"configurable": {"thread_id": "2"}})
        == [
            "0",
            "1",
            "2|Control(goto=Send(node='2', arg=3))",
            "2|Control(goto=Send(node='flaky', arg=4))",
            "2|3",
        ]
    )

    # check history
    history = [c async for c in graph.aget_state_history(config)]
    assert len(history) == 2

    # check messages
    assert orch_msgs == [MessageToOrchestrator(input=input, config=config)] + [
        {
            "config": {
                "callbacks": None,
                "configurable": {
                    "__pregel_ensure_latest": True,
                    "__pregel_dedupe_tasks": True,
                    "__pregel_resuming": False,
                    "checkpoint_id": c.config["configurable"]["checkpoint_id"],
                    "checkpoint_ns": "",
                    "thread_id": "1",
                },
                "metadata": AnyDict(),
                "recursion_limit": 25,
                "tags": [],
            },
            "input": None,
            "finally_send": None,
        }
        for c in reversed(history)
        for _ in c.tasks
    ]
    assert exec_msgs == [
        {
            "config": {
                "callbacks": None,
                "configurable": {
                    "__pregel_ensure_latest": True,
                    "__pregel_dedupe_tasks": True,
                    "__pregel_resuming": False,
                    "checkpoint_id": c.config["configurable"]["checkpoint_id"],
                    "checkpoint_ns": "",
                    "thread_id": "1",
                },
                "metadata": AnyDict(),
                "recursion_limit": 25,
                "tags": [],
            },
            "task": {
                "id": t.id,
                "path": _convert_path(t.path),
            },
            "finally_send": None,
        }
        for c in reversed(history)
        for t in c.tasks
    ]

    # resume the thread
    async with AIOKafkaProducer(value_serializer=serde.dumps) as producer:
        await producer.send_and_wait(
            topics.orchestrator,
            MessageToOrchestrator(input=None, config=config),
        )

    orch_msgs, exec_msgs = await drain_topics_async(topics, graph)

    # check final state
    state = await graph.aget_state(config)
    assert state.next == ()
    assert (
        state.values
        == await graph_compare.ainvoke(None, {"configurable": {"thread_id": "2"}})
        == [
            "0",
            "1",
            "2|Control(goto=Send(node='2', arg=3))",
            "2|Control(goto=Send(node='flaky', arg=4))",
            "2|3",
            "flaky|4",
            "3",
            "3.1",
        ]
    )

    # check history
    history = [c async for c in graph.aget_state_history(config)]
    assert len(history) == 4

    # check executions
    # node "2" doesn't get called again, as we recover writes saved before
    assert graph.builder.nodes["2"].runnable.func.ticks == 3
    # node "flaky" gets called again, as it was interrupted
    assert graph.builder.nodes["flaky"].runnable.func.ticks == 2


def _convert_path(
    path: tuple[Union[str, int, tuple], ...],
) -> list[Union[str, int, list]]:
    return list(_convert_path(p) if isinstance(p, tuple) else p for p in path)