MCP Wikipedia Server
by kaman05010
main.py•129 kB
from __future__ import annotations
import asyncio
import concurrent
import concurrent.futures
import queue
import warnings
import weakref
from collections import defaultdict, deque
from collections.abc import AsyncIterator, Iterator, Mapping, Sequence
from dataclasses import is_dataclass
from functools import partial
from inspect import isclass
from typing import Any, Callable, Generic, Optional, Union, cast, get_type_hints
from uuid import UUID, uuid5
from langchain_core.globals import get_debug
from langchain_core.runnables import (
RunnableSequence,
)
from langchain_core.runnables.base import Input, Output
from langchain_core.runnables.config import (
RunnableConfig,
get_async_callback_manager_for_config,
get_callback_manager_for_config,
)
from langchain_core.runnables.graph import Graph
from pydantic import BaseModel, TypeAdapter
from typing_extensions import Self, Unpack, deprecated, is_typeddict
from langgraph._internal._config import (
ensure_config,
merge_configs,
patch_checkpoint_map,
patch_config,
patch_configurable,
recast_checkpoint_ns,
)
from langgraph._internal._constants import (
CACHE_NS_WRITES,
CONF,
CONFIG_KEY_CACHE,
CONFIG_KEY_CHECKPOINT_ID,
CONFIG_KEY_CHECKPOINT_NS,
CONFIG_KEY_CHECKPOINTER,
CONFIG_KEY_DURABILITY,
CONFIG_KEY_NODE_FINISHED,
CONFIG_KEY_READ,
CONFIG_KEY_RUNNER_SUBMIT,
CONFIG_KEY_RUNTIME,
CONFIG_KEY_SEND,
CONFIG_KEY_STREAM,
CONFIG_KEY_TASK_ID,
CONFIG_KEY_THREAD_ID,
ERROR,
INPUT,
INTERRUPT,
NS_END,
NS_SEP,
NULL_TASK_ID,
PUSH,
TASKS,
)
from langgraph._internal._pydantic import create_model
from langgraph._internal._queue import ( # type: ignore[attr-defined]
AsyncQueue,
SyncQueue,
)
from langgraph._internal._runnable import (
Runnable,
RunnableLike,
RunnableSeq,
coerce_to_runnable,
)
from langgraph._internal._typing import MISSING, DeprecatedKwargs
from langgraph.cache.base import BaseCache
from langgraph.channels.base import BaseChannel
from langgraph.channels.topic import Topic
from langgraph.checkpoint.base import (
BaseCheckpointSaver,
Checkpoint,
CheckpointTuple,
)
from langgraph.config import get_config
from langgraph.constants import END
from langgraph.errors import (
ErrorCode,
GraphRecursionError,
InvalidUpdateError,
create_error_message,
)
from langgraph.managed.base import ManagedValueSpec
from langgraph.pregel._algo import (
PregelTaskWrites,
_scratchpad,
apply_writes,
local_read,
prepare_next_tasks,
)
from langgraph.pregel._call import identifier
from langgraph.pregel._checkpoint import (
channels_from_checkpoint,
copy_checkpoint,
create_checkpoint,
empty_checkpoint,
)
from langgraph.pregel._draw import draw_graph
from langgraph.pregel._io import map_input, read_channels
from langgraph.pregel._loop import AsyncPregelLoop, SyncPregelLoop
from langgraph.pregel._messages import StreamMessagesHandler
from langgraph.pregel._read import DEFAULT_BOUND, PregelNode
from langgraph.pregel._retry import RetryPolicy
from langgraph.pregel._runner import PregelRunner
from langgraph.pregel._utils import get_new_channel_versions
from langgraph.pregel._validate import validate_graph, validate_keys
from langgraph.pregel._write import ChannelWrite, ChannelWriteEntry
from langgraph.pregel.debug import get_bolded_text, get_colored_text, tasks_w_writes
from langgraph.pregel.protocol import PregelProtocol, StreamChunk, StreamProtocol
from langgraph.runtime import DEFAULT_RUNTIME, Runtime
from langgraph.store.base import BaseStore
from langgraph.types import (
All,
CachePolicy,
Checkpointer,
Command,
Durability,
Interrupt,
Send,
StateSnapshot,
StateUpdate,
StreamMode,
)
from langgraph.typing import ContextT, InputT, OutputT, StateT
from langgraph.warnings import LangGraphDeprecatedSinceV10
try:
from langchain_core.tracers._streaming import _StreamingCallbackHandler
except ImportError:
_StreamingCallbackHandler = None # type: ignore
__all__ = ("NodeBuilder", "Pregel")
_WriteValue = Union[Callable[[Input], Output], Any]
class NodeBuilder:
__slots__ = (
"_channels",
"_triggers",
"_tags",
"_metadata",
"_writes",
"_bound",
"_retry_policy",
"_cache_policy",
)
_channels: str | list[str]
_triggers: list[str]
_tags: list[str]
_metadata: dict[str, Any]
_writes: list[ChannelWriteEntry]
_bound: Runnable
_retry_policy: list[RetryPolicy]
_cache_policy: CachePolicy | None
def __init__(
self,
) -> None:
self._channels = []
self._triggers = []
self._tags = []
self._metadata = {}
self._writes = []
self._bound = DEFAULT_BOUND
self._retry_policy = []
self._cache_policy = None
def subscribe_only(
self,
channel: str,
) -> Self:
"""Subscribe to a single channel."""
if not self._channels:
self._channels = channel
else:
raise ValueError(
"Cannot subscribe to single channels when other channels are already subscribed to"
)
self._triggers.append(channel)
return self
def subscribe_to(
self,
*channels: str,
read: bool = True,
) -> Self:
"""Add channels to subscribe to. Node will be invoked when any of these
channels are updated, with a dict of the channel values as input.
Args:
channels: Channel name(s) to subscribe to
read: If True, the channels will be included in the input to the node.
Otherwise, they will trigger the node without being sent in input.
Returns:
Self for chaining
"""
if isinstance(self._channels, str):
raise ValueError(
"Cannot subscribe to channels when subscribed to a single channel"
)
if read:
if not self._channels:
self._channels = list(channels)
else:
self._channels.extend(channels)
if isinstance(channels, str):
self._triggers.append(channels)
else:
self._triggers.extend(channels)
return self
def read_from(
self,
*channels: str,
) -> Self:
"""Adds the specified channels to read from, without subscribing to them."""
assert isinstance(self._channels, list), (
"Cannot read additional channels when subscribed to single channels"
)
self._channels.extend(channels)
return self
def do(
self,
node: RunnableLike,
) -> Self:
"""Adds the specified node."""
if self._bound is not DEFAULT_BOUND:
self._bound = RunnableSeq(
self._bound, coerce_to_runnable(node, name=None, trace=True)
)
else:
self._bound = coerce_to_runnable(node, name=None, trace=True)
return self
def write_to(
self,
*channels: str | ChannelWriteEntry,
**kwargs: _WriteValue,
) -> Self:
"""Add channel writes.
Args:
*channels: Channel names to write to
**kwargs: Channel name and value mappings
Returns:
Self for chaining
"""
self._writes.extend(
ChannelWriteEntry(c) if isinstance(c, str) else c for c in channels
)
self._writes.extend(
ChannelWriteEntry(k, mapper=v)
if callable(v)
else ChannelWriteEntry(k, value=v)
for k, v in kwargs.items()
)
return self
def meta(self, *tags: str, **metadata: Any) -> Self:
"""Add tags or metadata to the node."""
self._tags.extend(tags)
self._metadata.update(metadata)
return self
def add_retry_policies(self, *policies: RetryPolicy) -> Self:
"""Adds retry policies to the node."""
self._retry_policy.extend(policies)
return self
def add_cache_policy(self, policy: CachePolicy) -> Self:
"""Adds cache policies to the node."""
self._cache_policy = policy
return self
def build(self) -> PregelNode:
"""Builds the node."""
return PregelNode(
channels=self._channels,
triggers=self._triggers,
tags=self._tags,
metadata=self._metadata,
writers=[ChannelWrite(self._writes)],
bound=self._bound,
retry_policy=self._retry_policy,
cache_policy=self._cache_policy,
)
class Pregel(
PregelProtocol[StateT, ContextT, InputT, OutputT],
Generic[StateT, ContextT, InputT, OutputT],
):
"""Pregel manages the runtime behavior for LangGraph applications.
## Overview
Pregel combines [**actors**](https://en.wikipedia.org/wiki/Actor_model)
and **channels** into a single application.
**Actors** read data from channels and write data to channels.
Pregel organizes the execution of the application into multiple steps,
following the **Pregel Algorithm**/**Bulk Synchronous Parallel** model.
Each step consists of three phases:
- **Plan**: Determine which **actors** to execute in this step. For example,
in the first step, select the **actors** that subscribe to the special
**input** channels; in subsequent steps,
select the **actors** that subscribe to channels updated in the previous step.
- **Execution**: Execute all selected **actors** in parallel,
until all complete, or one fails, or a timeout is reached. During this
phase, channel updates are invisible to actors until the next step.
- **Update**: Update the channels with the values written by the **actors**
in this step.
Repeat until no **actors** are selected for execution, or a maximum number of
steps is reached.
## Actors
An **actor** is a `PregelNode`.
It subscribes to channels, reads data from them, and writes data to them.
It can be thought of as an **actor** in the Pregel algorithm.
`PregelNodes` implement LangChain's
Runnable interface.
## Channels
Channels are used to communicate between actors (`PregelNodes`).
Each channel has a value type, an update type, and an update function – which
takes a sequence of updates and
modifies the stored value. Channels can be used to send data from one chain to
another, or to send data from a chain to itself in a future step. LangGraph
provides a number of built-in channels:
### Basic channels: LastValue and Topic
- `LastValue`: The default channel, stores the last value sent to the channel,
useful for input and output values, or for sending data from one step to the next
- `Topic`: A configurable PubSub Topic, useful for sending multiple values
between *actors*, or for accumulating output. Can be configured to deduplicate
values, and/or to accumulate values over the course of multiple steps.
### Advanced channels: Context and BinaryOperatorAggregate
- `Context`: exposes the value of a context manager, managing its lifecycle.
Useful for accessing external resources that require setup and/or teardown. eg.
`client = Context(httpx.Client)`
- `BinaryOperatorAggregate`: stores a persistent value, updated by applying
a binary operator to the current value and each update
sent to the channel, useful for computing aggregates over multiple steps. eg.
`total = BinaryOperatorAggregate(int, operator.add)`
## Examples
Most users will interact with Pregel via a
[StateGraph (Graph API)][langgraph.graph.StateGraph] or via an
[entrypoint (Functional API)][langgraph.func.entrypoint].
However, for **advanced** use cases, Pregel can be used directly. If you're
not sure whether you need to use Pregel directly, then the answer is probably no
– you should use the Graph API or Functional API instead. These are higher-level
interfaces that will compile down to Pregel under the hood.
Here are some examples to give you a sense of how it works:
Example: Single node application
```python
from langgraph.channels import EphemeralValue
from langgraph.pregel import Pregel, NodeBuilder
node1 = (
NodeBuilder().subscribe_only("a")
.do(lambda x: x + x)
.write_to("b")
)
app = Pregel(
nodes={"node1": node1},
channels={
"a": EphemeralValue(str),
"b": EphemeralValue(str),
},
input_channels=["a"],
output_channels=["b"],
)
app.invoke({"a": "foo"})
```
```con
{'b': 'foofoo'}
```
Example: Using multiple nodes and multiple output channels
```python
from langgraph.channels import LastValue, EphemeralValue
from langgraph.pregel import Pregel, NodeBuilder
node1 = (
NodeBuilder().subscribe_only("a")
.do(lambda x: x + x)
.write_to("b")
)
node2 = (
NodeBuilder().subscribe_to("b")
.do(lambda x: x["b"] + x["b"])
.write_to("c")
)
app = Pregel(
nodes={"node1": node1, "node2": node2},
channels={
"a": EphemeralValue(str),
"b": LastValue(str),
"c": EphemeralValue(str),
},
input_channels=["a"],
output_channels=["b", "c"],
)
app.invoke({"a": "foo"})
```
```con
{'b': 'foofoo', 'c': 'foofoofoofoo'}
```
Example: Using a Topic channel
```python
from langgraph.channels import LastValue, EphemeralValue, Topic
from langgraph.pregel import Pregel, NodeBuilder
node1 = (
NodeBuilder().subscribe_only("a")
.do(lambda x: x + x)
.write_to("b", "c")
)
node2 = (
NodeBuilder().subscribe_only("b")
.do(lambda x: x + x)
.write_to("c")
)
app = Pregel(
nodes={"node1": node1, "node2": node2},
channels={
"a": EphemeralValue(str),
"b": EphemeralValue(str),
"c": Topic(str, accumulate=True),
},
input_channels=["a"],
output_channels=["c"],
)
app.invoke({"a": "foo"})
```
```pycon
{'c': ['foofoo', 'foofoofoofoo']}
```
Example: Using a BinaryOperatorAggregate channel
```python
from langgraph.channels import EphemeralValue, BinaryOperatorAggregate
from langgraph.pregel import Pregel, NodeBuilder
node1 = (
NodeBuilder().subscribe_only("a")
.do(lambda x: x + x)
.write_to("b", "c")
)
node2 = (
NodeBuilder().subscribe_only("b")
.do(lambda x: x + x)
.write_to("c")
)
def reducer(current, update):
if current:
return current + " | " + update
else:
return update
app = Pregel(
nodes={"node1": node1, "node2": node2},
channels={
"a": EphemeralValue(str),
"b": EphemeralValue(str),
"c": BinaryOperatorAggregate(str, operator=reducer),
},
input_channels=["a"],
output_channels=["c"]
)
app.invoke({"a": "foo"})
```
```con
{'c': 'foofoo | foofoofoofoo'}
```
Example: Introducing a cycle
This example demonstrates how to introduce a cycle in the graph, by having
a chain write to a channel it subscribes to. Execution will continue
until a None value is written to the channel.
```python
from langgraph.channels import EphemeralValue
from langgraph.pregel import Pregel, NodeBuilder, ChannelWriteEntry
example_node = (
NodeBuilder().subscribe_only("value")
.do(lambda x: x + x if len(x) < 10 else None)
.write_to(ChannelWriteEntry(channel="value", skip_none=True))
)
app = Pregel(
nodes={"example_node": example_node},
channels={
"value": EphemeralValue(str),
},
input_channels=["value"],
output_channels=["value"]
)
app.invoke({"value": "a"})
```
```con
{'value': 'aaaaaaaaaaaaaaaa'}
```
"""
nodes: dict[str, PregelNode]
channels: dict[str, BaseChannel | ManagedValueSpec]
stream_mode: StreamMode = "values"
"""Mode to stream output, defaults to 'values'."""
stream_eager: bool = False
"""Whether to force emitting stream events eagerly, automatically turned on
for stream_mode "messages" and "custom"."""
output_channels: str | Sequence[str]
stream_channels: str | Sequence[str] | None = None
"""Channels to stream, defaults to all channels not in reserved channels"""
interrupt_after_nodes: All | Sequence[str]
interrupt_before_nodes: All | Sequence[str]
input_channels: str | Sequence[str]
step_timeout: float | None = None
"""Maximum time to wait for a step to complete, in seconds. Defaults to None."""
debug: bool
"""Whether to print debug information during execution. Defaults to False."""
checkpointer: Checkpointer = None
"""Checkpointer used to save and load graph state. Defaults to None."""
store: BaseStore | None = None
"""Memory store to use for SharedValues. Defaults to None."""
cache: BaseCache | None = None
"""Cache to use for storing node results. Defaults to None."""
retry_policy: Sequence[RetryPolicy] = ()
"""Retry policies to use when running tasks. Empty set disables retries."""
cache_policy: CachePolicy | None = None
"""Cache policy to use for all nodes. Can be overridden by individual nodes.
Defaults to None."""
context_schema: type[ContextT] | None = None
"""Specifies the schema for the context object that will be passed to the workflow."""
config: RunnableConfig | None = None
name: str = "LangGraph"
trigger_to_nodes: Mapping[str, Sequence[str]]
def __init__(
self,
*,
nodes: dict[str, PregelNode | NodeBuilder],
channels: dict[str, BaseChannel | ManagedValueSpec] | None,
auto_validate: bool = True,
stream_mode: StreamMode = "values",
stream_eager: bool = False,
output_channels: str | Sequence[str],
stream_channels: str | Sequence[str] | None = None,
interrupt_after_nodes: All | Sequence[str] = (),
interrupt_before_nodes: All | Sequence[str] = (),
input_channels: str | Sequence[str],
step_timeout: float | None = None,
debug: bool | None = None,
checkpointer: BaseCheckpointSaver | None = None,
store: BaseStore | None = None,
cache: BaseCache | None = None,
retry_policy: RetryPolicy | Sequence[RetryPolicy] = (),
cache_policy: CachePolicy | None = None,
context_schema: type[ContextT] | None = None,
config: RunnableConfig | None = None,
trigger_to_nodes: Mapping[str, Sequence[str]] | None = None,
name: str = "LangGraph",
**deprecated_kwargs: Unpack[DeprecatedKwargs],
) -> None:
if (
config_type := deprecated_kwargs.get("config_type"),
MISSING,
) is not MISSING:
warnings.warn(
"`config_type` is deprecated and will be removed. Please use `context_schema` instead.",
category=LangGraphDeprecatedSinceV10,
stacklevel=2,
)
if context_schema is None:
context_schema = cast(type[ContextT], config_type)
self.nodes = {
k: v.build() if isinstance(v, NodeBuilder) else v for k, v in nodes.items()
}
self.channels = channels or {}
if TASKS in self.channels and not isinstance(self.channels[TASKS], Topic):
raise ValueError(
f"Channel '{TASKS}' is reserved and cannot be used in the graph."
)
else:
self.channels[TASKS] = Topic(Send, accumulate=False)
self.stream_mode = stream_mode
self.stream_eager = stream_eager
self.output_channels = output_channels
self.stream_channels = stream_channels
self.interrupt_after_nodes = interrupt_after_nodes
self.interrupt_before_nodes = interrupt_before_nodes
self.input_channels = input_channels
self.step_timeout = step_timeout
self.debug = debug if debug is not None else get_debug()
self.checkpointer = checkpointer
self.store = store
self.cache = cache
self.retry_policy = (
(retry_policy,) if isinstance(retry_policy, RetryPolicy) else retry_policy
)
self.cache_policy = cache_policy
self.context_schema = context_schema
self.config = config
self.trigger_to_nodes = trigger_to_nodes or {}
self.name = name
if auto_validate:
self.validate()
def get_graph(
self, config: RunnableConfig | None = None, *, xray: int | bool = False
) -> Graph:
"""Return a drawable representation of the computation graph."""
# gather subgraphs
if xray:
subgraphs = {
k: v.get_graph(
config,
xray=xray if isinstance(xray, bool) or xray <= 0 else xray - 1,
)
for k, v in self.get_subgraphs()
}
else:
subgraphs = {}
return draw_graph(
merge_configs(self.config, config),
nodes=self.nodes,
specs=self.channels,
input_channels=self.input_channels,
interrupt_after_nodes=self.interrupt_after_nodes,
interrupt_before_nodes=self.interrupt_before_nodes,
trigger_to_nodes=self.trigger_to_nodes,
checkpointer=self.checkpointer,
subgraphs=subgraphs,
)
async def aget_graph(
self, config: RunnableConfig | None = None, *, xray: int | bool = False
) -> Graph:
"""Return a drawable representation of the computation graph."""
# gather subgraphs
if xray:
subpregels: dict[str, PregelProtocol] = {
k: v async for k, v in self.aget_subgraphs()
}
subgraphs = {
k: v
for k, v in zip(
subpregels,
await asyncio.gather(
*(
p.aget_graph(
config,
xray=xray
if isinstance(xray, bool) or xray <= 0
else xray - 1,
)
for p in subpregels.values()
)
),
)
}
else:
subgraphs = {}
return draw_graph(
merge_configs(self.config, config),
nodes=self.nodes,
specs=self.channels,
input_channels=self.input_channels,
interrupt_after_nodes=self.interrupt_after_nodes,
interrupt_before_nodes=self.interrupt_before_nodes,
trigger_to_nodes=self.trigger_to_nodes,
checkpointer=self.checkpointer,
subgraphs=subgraphs,
)
def _repr_mimebundle_(self, **kwargs: Any) -> dict[str, Any]:
"""Mime bundle used by Jupyter to display the graph"""
return {
"text/plain": repr(self),
"image/png": self.get_graph().draw_mermaid_png(),
}
def copy(self, update: dict[str, Any] | None = None) -> Self:
attrs = {k: v for k, v in self.__dict__.items() if k != "__orig_class__"}
attrs.update(update or {})
return self.__class__(**attrs)
def with_config(self, config: RunnableConfig | None = None, **kwargs: Any) -> Self:
"""Create a copy of the Pregel object with an updated config."""
return self.copy(
{"config": merge_configs(self.config, config, cast(RunnableConfig, kwargs))}
)
def validate(self) -> Self:
validate_graph(
self.nodes,
{k: v for k, v in self.channels.items() if isinstance(v, BaseChannel)},
{k: v for k, v in self.channels.items() if not isinstance(v, BaseChannel)},
self.input_channels,
self.output_channels,
self.stream_channels,
self.interrupt_after_nodes,
self.interrupt_before_nodes,
)
self.trigger_to_nodes = _trigger_to_nodes(self.nodes)
return self
@deprecated(
"`config_schema` is deprecated. Use `get_context_jsonschema` for the relevant schema instead."
)
def config_schema(self, *, include: Sequence[str] | None = None) -> type[BaseModel]:
warnings.warn(
"`config_schema` is deprecated. Use `get_context_jsonschema` for the relevant schema instead.",
category=LangGraphDeprecatedSinceV10,
stacklevel=2,
)
include = include or []
fields = {
**(
{"configurable": (self.context_schema, None)}
if self.context_schema
else {}
),
**{
field_name: (field_type, None)
for field_name, field_type in get_type_hints(RunnableConfig).items()
if field_name in [i for i in include if i != "configurable"]
},
}
return create_model(self.get_name("Config"), field_definitions=fields)
@deprecated(
"`get_config_jsonschema` is deprecated. Use `get_context_jsonschema` instead."
)
def get_config_jsonschema(
self, *, include: Sequence[str] | None = None
) -> dict[str, Any]:
warnings.warn(
"`get_config_jsonschema` is deprecated. Use `get_context_jsonschema` instead.",
category=LangGraphDeprecatedSinceV10,
stacklevel=2,
)
with warnings.catch_warnings():
warnings.filterwarnings("ignore", category=LangGraphDeprecatedSinceV10)
schema = self.config_schema(include=include)
return schema.model_json_schema()
def get_context_jsonschema(self) -> dict[str, Any] | None:
if (context_schema := self.context_schema) is None:
return None
if isclass(context_schema) and issubclass(context_schema, BaseModel):
return context_schema.model_json_schema()
elif is_typeddict(context_schema) or is_dataclass(context_schema):
return TypeAdapter(context_schema).json_schema()
else:
raise ValueError(
f"Invalid context schema type: {context_schema}. Must be a BaseModel, TypedDict or dataclass."
)
@property
def InputType(self) -> Any:
if isinstance(self.input_channels, str):
channel = self.channels[self.input_channels]
if isinstance(channel, BaseChannel):
return channel.UpdateType
def get_input_schema(self, config: RunnableConfig | None = None) -> type[BaseModel]:
config = merge_configs(self.config, config)
if isinstance(self.input_channels, str):
return super().get_input_schema(config)
else:
return create_model(
self.get_name("Input"),
field_definitions={
k: (c.UpdateType, None)
for k in self.input_channels or self.channels.keys()
if (c := self.channels[k]) and isinstance(c, BaseChannel)
},
)
def get_input_jsonschema(
self, config: RunnableConfig | None = None
) -> dict[str, Any]:
schema = self.get_input_schema(config)
return schema.model_json_schema()
@property
def OutputType(self) -> Any:
if isinstance(self.output_channels, str):
channel = self.channels[self.output_channels]
if isinstance(channel, BaseChannel):
return channel.ValueType
def get_output_schema(
self, config: RunnableConfig | None = None
) -> type[BaseModel]:
config = merge_configs(self.config, config)
if isinstance(self.output_channels, str):
return super().get_output_schema(config)
else:
return create_model(
self.get_name("Output"),
field_definitions={
k: (c.ValueType, None)
for k in self.output_channels
if (c := self.channels[k]) and isinstance(c, BaseChannel)
},
)
def get_output_jsonschema(
self, config: RunnableConfig | None = None
) -> dict[str, Any]:
schema = self.get_output_schema(config)
return schema.model_json_schema()
@property
def stream_channels_list(self) -> Sequence[str]:
stream_channels = self.stream_channels_asis
return (
[stream_channels] if isinstance(stream_channels, str) else stream_channels
)
@property
def stream_channels_asis(self) -> str | Sequence[str]:
return self.stream_channels or [
k for k in self.channels if isinstance(self.channels[k], BaseChannel)
]
def get_subgraphs(
self, *, namespace: str | None = None, recurse: bool = False
) -> Iterator[tuple[str, PregelProtocol]]:
"""Get the subgraphs of the graph.
Args:
namespace: The namespace to filter the subgraphs by.
recurse: Whether to recurse into the subgraphs.
If False, only the immediate subgraphs will be returned.
Returns:
Iterator[tuple[str, PregelProtocol]]: An iterator of the (namespace, subgraph) pairs.
"""
for name, node in self.nodes.items():
# filter by prefix
if namespace is not None:
if not namespace.startswith(name):
continue
# find the subgraph, if any
graph = node.subgraphs[0] if node.subgraphs else None
# if found, yield recursively
if graph:
if name == namespace:
yield name, graph
return # we found it, stop searching
if namespace is None:
yield name, graph
if recurse and isinstance(graph, Pregel):
if namespace is not None:
namespace = namespace[len(name) + 1 :]
yield from (
(f"{name}{NS_SEP}{n}", s)
for n, s in graph.get_subgraphs(
namespace=namespace, recurse=recurse
)
)
async def aget_subgraphs(
self, *, namespace: str | None = None, recurse: bool = False
) -> AsyncIterator[tuple[str, PregelProtocol]]:
"""Get the subgraphs of the graph.
Args:
namespace: The namespace to filter the subgraphs by.
recurse: Whether to recurse into the subgraphs.
If False, only the immediate subgraphs will be returned.
Returns:
AsyncIterator[tuple[str, PregelProtocol]]: An iterator of the (namespace, subgraph) pairs.
"""
for name, node in self.get_subgraphs(namespace=namespace, recurse=recurse):
yield name, node
def _migrate_checkpoint(self, checkpoint: Checkpoint) -> None:
"""Migrate a saved checkpoint to new channel layout."""
if checkpoint["v"] < 4 and checkpoint.get("pending_sends"):
pending_sends: list[Send] = checkpoint.pop("pending_sends")
checkpoint["channel_values"][TASKS] = pending_sends
checkpoint["channel_versions"][TASKS] = max(
checkpoint["channel_versions"].values()
)
def _prepare_state_snapshot(
self,
config: RunnableConfig,
saved: CheckpointTuple | None,
recurse: BaseCheckpointSaver | None = None,
apply_pending_writes: bool = False,
) -> StateSnapshot:
if not saved:
return StateSnapshot(
values={},
next=(),
config=config,
metadata=None,
created_at=None,
parent_config=None,
tasks=(),
interrupts=(),
)
# migrate checkpoint if needed
self._migrate_checkpoint(saved.checkpoint)
step = saved.metadata.get("step", -1) + 1
stop = step + 2
channels, managed = channels_from_checkpoint(
self.channels,
saved.checkpoint,
)
# tasks for this checkpoint
next_tasks = prepare_next_tasks(
saved.checkpoint,
saved.pending_writes or [],
self.nodes,
channels,
managed,
saved.config,
step,
stop,
for_execution=True,
store=self.store,
checkpointer=(
self.checkpointer
if isinstance(self.checkpointer, BaseCheckpointSaver)
else None
),
manager=None,
)
# get the subgraphs
subgraphs = dict(self.get_subgraphs())
parent_ns = saved.config[CONF].get(CONFIG_KEY_CHECKPOINT_NS, "")
task_states: dict[str, RunnableConfig | StateSnapshot] = {}
for task in next_tasks.values():
if task.name not in subgraphs:
continue
# assemble checkpoint_ns for this task
task_ns = f"{task.name}{NS_END}{task.id}"
if parent_ns:
task_ns = f"{parent_ns}{NS_SEP}{task_ns}"
if not recurse:
# set config as signal that subgraph checkpoints exist
config = {
CONF: {
"thread_id": saved.config[CONF]["thread_id"],
CONFIG_KEY_CHECKPOINT_NS: task_ns,
}
}
task_states[task.id] = config
else:
# get the state of the subgraph
config = {
CONF: {
CONFIG_KEY_CHECKPOINTER: recurse,
"thread_id": saved.config[CONF]["thread_id"],
CONFIG_KEY_CHECKPOINT_NS: task_ns,
}
}
task_states[task.id] = subgraphs[task.name].get_state(
config, subgraphs=True
)
# apply pending writes
if null_writes := [
w[1:] for w in saved.pending_writes or [] if w[0] == NULL_TASK_ID
]:
apply_writes(
saved.checkpoint,
channels,
[PregelTaskWrites((), INPUT, null_writes, [])],
None,
self.trigger_to_nodes,
)
if apply_pending_writes and saved.pending_writes:
for tid, k, v in saved.pending_writes:
if k in (ERROR, INTERRUPT):
continue
if tid not in next_tasks:
continue
next_tasks[tid].writes.append((k, v))
if tasks := [t for t in next_tasks.values() if t.writes]:
apply_writes(
saved.checkpoint, channels, tasks, None, self.trigger_to_nodes
)
tasks_with_writes = tasks_w_writes(
next_tasks.values(),
saved.pending_writes,
task_states,
self.stream_channels_asis,
)
# assemble the state snapshot
return StateSnapshot(
read_channels(channels, self.stream_channels_asis),
tuple(t.name for t in next_tasks.values() if not t.writes),
patch_checkpoint_map(saved.config, saved.metadata),
saved.metadata,
saved.checkpoint["ts"],
patch_checkpoint_map(saved.parent_config, saved.metadata),
tasks_with_writes,
tuple([i for task in tasks_with_writes for i in task.interrupts]),
)
async def _aprepare_state_snapshot(
self,
config: RunnableConfig,
saved: CheckpointTuple | None,
recurse: BaseCheckpointSaver | None = None,
apply_pending_writes: bool = False,
) -> StateSnapshot:
if not saved:
return StateSnapshot(
values={},
next=(),
config=config,
metadata=None,
created_at=None,
parent_config=None,
tasks=(),
interrupts=(),
)
# migrate checkpoint if needed
self._migrate_checkpoint(saved.checkpoint)
step = saved.metadata.get("step", -1) + 1
stop = step + 2
channels, managed = channels_from_checkpoint(
self.channels,
saved.checkpoint,
)
# tasks for this checkpoint
next_tasks = prepare_next_tasks(
saved.checkpoint,
saved.pending_writes or [],
self.nodes,
channels,
managed,
saved.config,
step,
stop,
for_execution=True,
store=self.store,
checkpointer=(
self.checkpointer
if isinstance(self.checkpointer, BaseCheckpointSaver)
else None
),
manager=None,
)
# get the subgraphs
subgraphs = {n: g async for n, g in self.aget_subgraphs()}
parent_ns = saved.config[CONF].get(CONFIG_KEY_CHECKPOINT_NS, "")
task_states: dict[str, RunnableConfig | StateSnapshot] = {}
for task in next_tasks.values():
if task.name not in subgraphs:
continue
# assemble checkpoint_ns for this task
task_ns = f"{task.name}{NS_END}{task.id}"
if parent_ns:
task_ns = f"{parent_ns}{NS_SEP}{task_ns}"
if not recurse:
# set config as signal that subgraph checkpoints exist
config = {
CONF: {
"thread_id": saved.config[CONF]["thread_id"],
CONFIG_KEY_CHECKPOINT_NS: task_ns,
}
}
task_states[task.id] = config
else:
# get the state of the subgraph
config = {
CONF: {
CONFIG_KEY_CHECKPOINTER: recurse,
"thread_id": saved.config[CONF]["thread_id"],
CONFIG_KEY_CHECKPOINT_NS: task_ns,
}
}
task_states[task.id] = await subgraphs[task.name].aget_state(
config, subgraphs=True
)
# apply pending writes
if null_writes := [
w[1:] for w in saved.pending_writes or [] if w[0] == NULL_TASK_ID
]:
apply_writes(
saved.checkpoint,
channels,
[PregelTaskWrites((), INPUT, null_writes, [])],
None,
self.trigger_to_nodes,
)
if apply_pending_writes and saved.pending_writes:
for tid, k, v in saved.pending_writes:
if k in (ERROR, INTERRUPT):
continue
if tid not in next_tasks:
continue
next_tasks[tid].writes.append((k, v))
if tasks := [t for t in next_tasks.values() if t.writes]:
apply_writes(
saved.checkpoint, channels, tasks, None, self.trigger_to_nodes
)
tasks_with_writes = tasks_w_writes(
next_tasks.values(),
saved.pending_writes,
task_states,
self.stream_channels_asis,
)
# assemble the state snapshot
return StateSnapshot(
read_channels(channels, self.stream_channels_asis),
tuple(t.name for t in next_tasks.values() if not t.writes),
patch_checkpoint_map(saved.config, saved.metadata),
saved.metadata,
saved.checkpoint["ts"],
patch_checkpoint_map(saved.parent_config, saved.metadata),
tasks_with_writes,
tuple([i for task in tasks_with_writes for i in task.interrupts]),
)
def get_state(
self, config: RunnableConfig, *, subgraphs: bool = False
) -> StateSnapshot:
"""Get the current state of the graph."""
checkpointer: BaseCheckpointSaver | None = ensure_config(config)[CONF].get(
CONFIG_KEY_CHECKPOINTER, self.checkpointer
)
if not checkpointer:
raise ValueError("No checkpointer set")
if (
checkpoint_ns := config[CONF].get(CONFIG_KEY_CHECKPOINT_NS, "")
) and CONFIG_KEY_CHECKPOINTER not in config[CONF]:
# remove task_ids from checkpoint_ns
recast = recast_checkpoint_ns(checkpoint_ns)
# find the subgraph with the matching name
for _, pregel in self.get_subgraphs(namespace=recast, recurse=True):
return pregel.get_state(
patch_configurable(config, {CONFIG_KEY_CHECKPOINTER: checkpointer}),
subgraphs=subgraphs,
)
else:
raise ValueError(f"Subgraph {recast} not found")
config = merge_configs(self.config, config) if self.config else config
if self.checkpointer is True:
ns = cast(str, config[CONF][CONFIG_KEY_CHECKPOINT_NS])
config = merge_configs(
config, {CONF: {CONFIG_KEY_CHECKPOINT_NS: recast_checkpoint_ns(ns)}}
)
thread_id = config[CONF][CONFIG_KEY_THREAD_ID]
if not isinstance(thread_id, str):
config[CONF][CONFIG_KEY_THREAD_ID] = str(thread_id)
saved = checkpointer.get_tuple(config)
return self._prepare_state_snapshot(
config,
saved,
recurse=checkpointer if subgraphs else None,
apply_pending_writes=CONFIG_KEY_CHECKPOINT_ID not in config[CONF],
)
async def aget_state(
self, config: RunnableConfig, *, subgraphs: bool = False
) -> StateSnapshot:
"""Get the current state of the graph."""
checkpointer: BaseCheckpointSaver | None = ensure_config(config)[CONF].get(
CONFIG_KEY_CHECKPOINTER, self.checkpointer
)
if not checkpointer:
raise ValueError("No checkpointer set")
if (
checkpoint_ns := config[CONF].get(CONFIG_KEY_CHECKPOINT_NS, "")
) and CONFIG_KEY_CHECKPOINTER not in config[CONF]:
# remove task_ids from checkpoint_ns
recast = recast_checkpoint_ns(checkpoint_ns)
# find the subgraph with the matching name
async for _, pregel in self.aget_subgraphs(namespace=recast, recurse=True):
return await pregel.aget_state(
patch_configurable(config, {CONFIG_KEY_CHECKPOINTER: checkpointer}),
subgraphs=subgraphs,
)
else:
raise ValueError(f"Subgraph {recast} not found")
config = merge_configs(self.config, config) if self.config else config
if self.checkpointer is True:
ns = cast(str, config[CONF][CONFIG_KEY_CHECKPOINT_NS])
config = merge_configs(
config, {CONF: {CONFIG_KEY_CHECKPOINT_NS: recast_checkpoint_ns(ns)}}
)
thread_id = config[CONF][CONFIG_KEY_THREAD_ID]
if not isinstance(thread_id, str):
config[CONF][CONFIG_KEY_THREAD_ID] = str(thread_id)
saved = await checkpointer.aget_tuple(config)
return await self._aprepare_state_snapshot(
config,
saved,
recurse=checkpointer if subgraphs else None,
apply_pending_writes=CONFIG_KEY_CHECKPOINT_ID not in config[CONF],
)
def get_state_history(
self,
config: RunnableConfig,
*,
filter: dict[str, Any] | None = None,
before: RunnableConfig | None = None,
limit: int | None = None,
) -> Iterator[StateSnapshot]:
"""Get the history of the state of the graph."""
config = ensure_config(config)
checkpointer: BaseCheckpointSaver | None = ensure_config(config)[CONF].get(
CONFIG_KEY_CHECKPOINTER, self.checkpointer
)
if not checkpointer:
raise ValueError("No checkpointer set")
if (
checkpoint_ns := config[CONF].get(CONFIG_KEY_CHECKPOINT_NS, "")
) and CONFIG_KEY_CHECKPOINTER not in config[CONF]:
# remove task_ids from checkpoint_ns
recast = recast_checkpoint_ns(checkpoint_ns)
# find the subgraph with the matching name
for _, pregel in self.get_subgraphs(namespace=recast, recurse=True):
yield from pregel.get_state_history(
patch_configurable(config, {CONFIG_KEY_CHECKPOINTER: checkpointer}),
filter=filter,
before=before,
limit=limit,
)
return
else:
raise ValueError(f"Subgraph {recast} not found")
config = merge_configs(
self.config,
config,
{
CONF: {
CONFIG_KEY_CHECKPOINT_NS: checkpoint_ns,
CONFIG_KEY_THREAD_ID: str(config[CONF][CONFIG_KEY_THREAD_ID]),
}
},
)
# eagerly consume list() to avoid holding up the db cursor
for checkpoint_tuple in list(
checkpointer.list(config, before=before, limit=limit, filter=filter)
):
yield self._prepare_state_snapshot(
checkpoint_tuple.config, checkpoint_tuple
)
async def aget_state_history(
self,
config: RunnableConfig,
*,
filter: dict[str, Any] | None = None,
before: RunnableConfig | None = None,
limit: int | None = None,
) -> AsyncIterator[StateSnapshot]:
"""Asynchronously get the history of the state of the graph."""
config = ensure_config(config)
checkpointer: BaseCheckpointSaver | None = ensure_config(config)[CONF].get(
CONFIG_KEY_CHECKPOINTER, self.checkpointer
)
if not checkpointer:
raise ValueError("No checkpointer set")
if (
checkpoint_ns := config[CONF].get(CONFIG_KEY_CHECKPOINT_NS, "")
) and CONFIG_KEY_CHECKPOINTER not in config[CONF]:
# remove task_ids from checkpoint_ns
recast = recast_checkpoint_ns(checkpoint_ns)
# find the subgraph with the matching name
async for _, pregel in self.aget_subgraphs(namespace=recast, recurse=True):
async for state in pregel.aget_state_history(
patch_configurable(config, {CONFIG_KEY_CHECKPOINTER: checkpointer}),
filter=filter,
before=before,
limit=limit,
):
yield state
return
else:
raise ValueError(f"Subgraph {recast} not found")
config = merge_configs(
self.config,
config,
{
CONF: {
CONFIG_KEY_CHECKPOINT_NS: checkpoint_ns,
CONFIG_KEY_THREAD_ID: str(config[CONF][CONFIG_KEY_THREAD_ID]),
}
},
)
# eagerly consume list() to avoid holding up the db cursor
for checkpoint_tuple in [
c
async for c in checkpointer.alist(
config, before=before, limit=limit, filter=filter
)
]:
yield await self._aprepare_state_snapshot(
checkpoint_tuple.config, checkpoint_tuple
)
def bulk_update_state(
self,
config: RunnableConfig,
supersteps: Sequence[Sequence[StateUpdate]],
) -> RunnableConfig:
"""Apply updates to the graph state in bulk. Requires a checkpointer to be set.
Args:
config: The config to apply the updates to.
supersteps: A list of supersteps, each including a list of updates to apply sequentially to a graph state.
Each update is a tuple of the form `(values, as_node, task_id)` where task_id is optional.
Raises:
ValueError: If no checkpointer is set or no updates are provided.
InvalidUpdateError: If an invalid update is provided.
Returns:
RunnableConfig: The updated config.
"""
checkpointer: BaseCheckpointSaver | None = ensure_config(config)[CONF].get(
CONFIG_KEY_CHECKPOINTER, self.checkpointer
)
if not checkpointer:
raise ValueError("No checkpointer set")
if len(supersteps) == 0:
raise ValueError("No supersteps provided")
if any(len(u) == 0 for u in supersteps):
raise ValueError("No updates provided")
# delegate to subgraph
if (
checkpoint_ns := config[CONF].get(CONFIG_KEY_CHECKPOINT_NS, "")
) and CONFIG_KEY_CHECKPOINTER not in config[CONF]:
# remove task_ids from checkpoint_ns
recast = recast_checkpoint_ns(checkpoint_ns)
# find the subgraph with the matching name
for _, pregel in self.get_subgraphs(namespace=recast, recurse=True):
return pregel.bulk_update_state(
patch_configurable(config, {CONFIG_KEY_CHECKPOINTER: checkpointer}),
supersteps,
)
else:
raise ValueError(f"Subgraph {recast} not found")
def perform_superstep(
input_config: RunnableConfig, updates: Sequence[StateUpdate]
) -> RunnableConfig:
# get last checkpoint
config = ensure_config(self.config, input_config)
saved = checkpointer.get_tuple(config)
if saved is not None:
self._migrate_checkpoint(saved.checkpoint)
checkpoint = (
copy_checkpoint(saved.checkpoint) if saved else empty_checkpoint()
)
checkpoint_previous_versions = (
saved.checkpoint["channel_versions"].copy() if saved else {}
)
step = saved.metadata.get("step", -1) if saved else -1
# merge configurable fields with previous checkpoint config
checkpoint_config = patch_configurable(
config,
{
CONFIG_KEY_CHECKPOINT_NS: config[CONF].get(
CONFIG_KEY_CHECKPOINT_NS, ""
)
},
)
if saved:
checkpoint_config = patch_configurable(config, saved.config[CONF])
channels, managed = channels_from_checkpoint(
self.channels,
checkpoint,
)
values, as_node = updates[0][:2]
# no values as END, just clear all tasks
if values is None and as_node == END:
if len(updates) > 1:
raise InvalidUpdateError(
"Cannot apply multiple updates when clearing state"
)
if saved is not None:
# tasks for this checkpoint
next_tasks = prepare_next_tasks(
checkpoint,
saved.pending_writes or [],
self.nodes,
channels,
managed,
saved.config,
step + 1,
step + 3,
for_execution=True,
store=self.store,
checkpointer=checkpointer,
manager=None,
)
# apply null writes
if null_writes := [
w[1:]
for w in saved.pending_writes or []
if w[0] == NULL_TASK_ID
]:
apply_writes(
checkpoint,
channels,
[PregelTaskWrites((), INPUT, null_writes, [])],
checkpointer.get_next_version,
self.trigger_to_nodes,
)
# apply writes from tasks that already ran
for tid, k, v in saved.pending_writes or []:
if k in (ERROR, INTERRUPT):
continue
if tid not in next_tasks:
continue
next_tasks[tid].writes.append((k, v))
# clear all current tasks
apply_writes(
checkpoint,
channels,
next_tasks.values(),
checkpointer.get_next_version,
self.trigger_to_nodes,
)
# save checkpoint
next_config = checkpointer.put(
checkpoint_config,
create_checkpoint(checkpoint, channels, step),
{
"source": "update",
"step": step + 1,
"parents": saved.metadata.get("parents", {}) if saved else {},
},
get_new_channel_versions(
checkpoint_previous_versions,
checkpoint["channel_versions"],
),
)
return patch_checkpoint_map(
next_config, saved.metadata if saved else None
)
# act as an input
if as_node == INPUT:
if len(updates) > 1:
raise InvalidUpdateError(
"Cannot apply multiple updates when updating as input"
)
if input_writes := deque(map_input(self.input_channels, values)):
apply_writes(
checkpoint,
channels,
[PregelTaskWrites((), INPUT, input_writes, [])],
checkpointer.get_next_version,
self.trigger_to_nodes,
)
# apply input write to channels
next_step = (
step + 1
if saved and saved.metadata.get("step") is not None
else -1
)
next_config = checkpointer.put(
checkpoint_config,
create_checkpoint(checkpoint, channels, next_step),
{
"source": "input",
"step": next_step,
"parents": saved.metadata.get("parents", {})
if saved
else {},
},
get_new_channel_versions(
checkpoint_previous_versions,
checkpoint["channel_versions"],
),
)
# store the writes
checkpointer.put_writes(
next_config,
input_writes,
str(uuid5(UUID(checkpoint["id"]), INPUT)),
)
return patch_checkpoint_map(
next_config, saved.metadata if saved else None
)
else:
raise InvalidUpdateError(
f"Received no input writes for {self.input_channels}"
)
# copy checkpoint
if as_node == "__copy__":
if len(updates) > 1:
raise InvalidUpdateError(
"Cannot copy checkpoint with multiple updates"
)
if saved is None:
raise InvalidUpdateError("Cannot copy a non-existent checkpoint")
next_checkpoint = create_checkpoint(checkpoint, None, step)
# copy checkpoint
next_config = checkpointer.put(
saved.parent_config
or patch_configurable(
saved.config, {CONFIG_KEY_CHECKPOINT_ID: None}
),
next_checkpoint,
{
"source": "fork",
"step": step + 1,
"parents": saved.metadata.get("parents", {}),
},
{},
)
# we want to both clone a checkpoint and update state in one go.
# reuse the same task ID if possible.
if isinstance(values, list) and len(values) > 0:
# figure out the task IDs for the next update checkpoint
next_tasks = prepare_next_tasks(
next_checkpoint,
saved.pending_writes or [],
self.nodes,
channels,
managed,
next_config,
step + 2,
step + 4,
for_execution=True,
store=self.store,
checkpointer=checkpointer,
manager=None,
)
tasks_group_by = defaultdict(list)
user_group_by: dict[str, list[StateUpdate]] = defaultdict(list)
for task in next_tasks.values():
tasks_group_by[task.name].append(task.id)
for item in values:
if not isinstance(item, Sequence):
raise InvalidUpdateError(
f"Invalid update item: {item} when copying checkpoint"
)
values, as_node = item[:2]
user_group = user_group_by[as_node]
tasks_group = tasks_group_by[as_node]
target_idx = len(user_group)
task_id = (
tasks_group[target_idx]
if target_idx < len(tasks_group)
else None
)
user_group_by[as_node].append(
StateUpdate(values=values, as_node=as_node, task_id=task_id)
)
return perform_superstep(
patch_checkpoint_map(next_config, saved.metadata),
[item for lst in user_group_by.values() for item in lst],
)
return patch_checkpoint_map(next_config, saved.metadata)
# apply pending writes, if not on specific checkpoint
if (
CONFIG_KEY_CHECKPOINT_ID not in config[CONF]
and saved is not None
and saved.pending_writes
):
# tasks for this checkpoint
next_tasks = prepare_next_tasks(
checkpoint,
saved.pending_writes,
self.nodes,
channels,
managed,
saved.config,
step + 1,
step + 3,
for_execution=True,
store=self.store,
checkpointer=checkpointer,
manager=None,
)
# apply null writes
if null_writes := [
w[1:] for w in saved.pending_writes or [] if w[0] == NULL_TASK_ID
]:
apply_writes(
checkpoint,
channels,
[PregelTaskWrites((), INPUT, null_writes, [])],
checkpointer.get_next_version,
self.trigger_to_nodes,
)
# apply writes
for tid, k, v in saved.pending_writes:
if k in (ERROR, INTERRUPT):
continue
if tid not in next_tasks:
continue
next_tasks[tid].writes.append((k, v))
if tasks := [t for t in next_tasks.values() if t.writes]:
apply_writes(
checkpoint,
channels,
tasks,
checkpointer.get_next_version,
self.trigger_to_nodes,
)
valid_updates: list[tuple[str, dict[str, Any] | None, str | None]] = []
if len(updates) == 1:
values, as_node, task_id = updates[0]
# find last node that updated the state, if not provided
if as_node is None and len(self.nodes) == 1:
as_node = tuple(self.nodes)[0]
elif as_node is None and not any(
v
for vv in checkpoint["versions_seen"].values()
for v in vv.values()
):
if (
isinstance(self.input_channels, str)
and self.input_channels in self.nodes
):
as_node = self.input_channels
elif as_node is None:
last_seen_by_node = sorted(
(v, n)
for n, seen in checkpoint["versions_seen"].items()
if n in self.nodes
for v in seen.values()
)
# if two nodes updated the state at the same time, it's ambiguous
if last_seen_by_node:
if len(last_seen_by_node) == 1:
as_node = last_seen_by_node[0][1]
elif last_seen_by_node[-1][0] != last_seen_by_node[-2][0]:
as_node = last_seen_by_node[-1][1]
if as_node is None:
raise InvalidUpdateError("Ambiguous update, specify as_node")
if as_node not in self.nodes:
raise InvalidUpdateError(f"Node {as_node} does not exist")
valid_updates.append((as_node, values, task_id))
else:
for values, as_node, task_id in updates:
if as_node is None:
raise InvalidUpdateError(
"as_node is required when applying multiple updates"
)
if as_node not in self.nodes:
raise InvalidUpdateError(f"Node {as_node} does not exist")
valid_updates.append((as_node, values, task_id))
run_tasks: list[PregelTaskWrites] = []
run_task_ids: list[str] = []
for as_node, values, provided_task_id in valid_updates:
# create task to run all writers of the chosen node
writers = self.nodes[as_node].flat_writers
if not writers:
raise InvalidUpdateError(f"Node {as_node} has no writers")
writes: deque[tuple[str, Any]] = deque()
task = PregelTaskWrites((), as_node, writes, [INTERRUPT])
task_id = provided_task_id or str(
uuid5(UUID(checkpoint["id"]), INTERRUPT)
)
run_tasks.append(task)
run_task_ids.append(task_id)
run = RunnableSequence(*writers) if len(writers) > 1 else writers[0]
# execute task
run.invoke(
values,
patch_config(
config,
run_name=self.name + "UpdateState",
configurable={
# deque.extend is thread-safe
CONFIG_KEY_SEND: writes.extend,
CONFIG_KEY_TASK_ID: task_id,
CONFIG_KEY_READ: partial(
local_read,
_scratchpad(
None,
[],
task_id,
"",
None,
step,
step + 2,
),
channels,
managed,
task,
),
},
),
)
# save task writes
for task_id, task in zip(run_task_ids, run_tasks):
# channel writes are saved to current checkpoint
channel_writes = [w for w in task.writes if w[0] != PUSH]
if saved and channel_writes:
checkpointer.put_writes(checkpoint_config, channel_writes, task_id)
# apply to checkpoint and save
apply_writes(
checkpoint,
channels,
run_tasks,
checkpointer.get_next_version,
self.trigger_to_nodes,
)
checkpoint = create_checkpoint(checkpoint, channels, step + 1)
next_config = checkpointer.put(
checkpoint_config,
checkpoint,
{
"source": "update",
"step": step + 1,
"parents": saved.metadata.get("parents", {}) if saved else {},
},
get_new_channel_versions(
checkpoint_previous_versions, checkpoint["channel_versions"]
),
)
for task_id, task in zip(run_task_ids, run_tasks):
# save push writes
if push_writes := [w for w in task.writes if w[0] == PUSH]:
checkpointer.put_writes(next_config, push_writes, task_id)
return patch_checkpoint_map(next_config, saved.metadata if saved else None)
current_config = patch_configurable(
config, {CONFIG_KEY_THREAD_ID: str(config[CONF][CONFIG_KEY_THREAD_ID])}
)
for superstep in supersteps:
current_config = perform_superstep(current_config, superstep)
return current_config
async def abulk_update_state(
self,
config: RunnableConfig,
supersteps: Sequence[Sequence[StateUpdate]],
) -> RunnableConfig:
"""Asynchronously apply updates to the graph state in bulk. Requires a checkpointer to be set.
Args:
config: The config to apply the updates to.
supersteps: A list of supersteps, each including a list of updates to apply sequentially to a graph state.
Each update is a tuple of the form `(values, as_node, task_id)` where task_id is optional.
Raises:
ValueError: If no checkpointer is set or no updates are provided.
InvalidUpdateError: If an invalid update is provided.
Returns:
RunnableConfig: The updated config.
"""
checkpointer: BaseCheckpointSaver | None = ensure_config(config)[CONF].get(
CONFIG_KEY_CHECKPOINTER, self.checkpointer
)
if not checkpointer:
raise ValueError("No checkpointer set")
if len(supersteps) == 0:
raise ValueError("No supersteps provided")
if any(len(u) == 0 for u in supersteps):
raise ValueError("No updates provided")
# delegate to subgraph
if (
checkpoint_ns := config[CONF].get(CONFIG_KEY_CHECKPOINT_NS, "")
) and CONFIG_KEY_CHECKPOINTER not in config[CONF]:
# remove task_ids from checkpoint_ns
recast = recast_checkpoint_ns(checkpoint_ns)
# find the subgraph with the matching name
async for _, pregel in self.aget_subgraphs(namespace=recast, recurse=True):
return await pregel.abulk_update_state(
patch_configurable(config, {CONFIG_KEY_CHECKPOINTER: checkpointer}),
supersteps,
)
else:
raise ValueError(f"Subgraph {recast} not found")
async def aperform_superstep(
input_config: RunnableConfig, updates: Sequence[StateUpdate]
) -> RunnableConfig:
# get last checkpoint
config = ensure_config(self.config, input_config)
saved = await checkpointer.aget_tuple(config)
if saved is not None:
self._migrate_checkpoint(saved.checkpoint)
checkpoint = (
copy_checkpoint(saved.checkpoint) if saved else empty_checkpoint()
)
checkpoint_previous_versions = (
saved.checkpoint["channel_versions"].copy() if saved else {}
)
step = saved.metadata.get("step", -1) if saved else -1
# merge configurable fields with previous checkpoint config
checkpoint_config = patch_configurable(
config,
{
CONFIG_KEY_CHECKPOINT_NS: config[CONF].get(
CONFIG_KEY_CHECKPOINT_NS, ""
)
},
)
if saved:
checkpoint_config = patch_configurable(config, saved.config[CONF])
channels, managed = channels_from_checkpoint(
self.channels,
checkpoint,
)
values, as_node = updates[0][:2]
# no values, just clear all tasks
if values is None and as_node == END:
if len(updates) > 1:
raise InvalidUpdateError(
"Cannot apply multiple updates when clearing state"
)
if saved is not None:
# tasks for this checkpoint
next_tasks = prepare_next_tasks(
checkpoint,
saved.pending_writes or [],
self.nodes,
channels,
managed,
saved.config,
step + 1,
step + 3,
for_execution=True,
store=self.store,
checkpointer=checkpointer,
manager=None,
)
# apply null writes
if null_writes := [
w[1:]
for w in saved.pending_writes or []
if w[0] == NULL_TASK_ID
]:
apply_writes(
checkpoint,
channels,
[PregelTaskWrites((), INPUT, null_writes, [])],
checkpointer.get_next_version,
self.trigger_to_nodes,
)
# apply writes from tasks that already ran
for tid, k, v in saved.pending_writes or []:
if k in (ERROR, INTERRUPT):
continue
if tid not in next_tasks:
continue
next_tasks[tid].writes.append((k, v))
# clear all current tasks
apply_writes(
checkpoint,
channels,
next_tasks.values(),
checkpointer.get_next_version,
self.trigger_to_nodes,
)
# save checkpoint
next_config = await checkpointer.aput(
checkpoint_config,
create_checkpoint(checkpoint, channels, step),
{
"source": "update",
"step": step + 1,
"parents": saved.metadata.get("parents", {}) if saved else {},
},
get_new_channel_versions(
checkpoint_previous_versions, checkpoint["channel_versions"]
),
)
return patch_checkpoint_map(
next_config, saved.metadata if saved else None
)
# act as an input
if as_node == INPUT:
if len(updates) > 1:
raise InvalidUpdateError(
"Cannot apply multiple updates when updating as input"
)
if input_writes := deque(map_input(self.input_channels, values)):
apply_writes(
checkpoint,
channels,
[PregelTaskWrites((), INPUT, input_writes, [])],
checkpointer.get_next_version,
self.trigger_to_nodes,
)
# apply input write to channels
next_step = (
step + 1
if saved and saved.metadata.get("step") is not None
else -1
)
next_config = await checkpointer.aput(
checkpoint_config,
create_checkpoint(checkpoint, channels, next_step),
{
"source": "input",
"step": next_step,
"parents": saved.metadata.get("parents", {})
if saved
else {},
},
get_new_channel_versions(
checkpoint_previous_versions,
checkpoint["channel_versions"],
),
)
# store the writes
await checkpointer.aput_writes(
next_config,
input_writes,
str(uuid5(UUID(checkpoint["id"]), INPUT)),
)
return patch_checkpoint_map(
next_config, saved.metadata if saved else None
)
else:
raise InvalidUpdateError(
f"Received no input writes for {self.input_channels}"
)
# no values, copy checkpoint
if as_node == "__copy__":
if len(updates) > 1:
raise InvalidUpdateError(
"Cannot copy checkpoint with multiple updates"
)
if saved is None:
raise InvalidUpdateError("Cannot copy a non-existent checkpoint")
next_checkpoint = create_checkpoint(checkpoint, None, step)
# copy checkpoint
next_config = await checkpointer.aput(
saved.parent_config
or patch_configurable(
saved.config, {CONFIG_KEY_CHECKPOINT_ID: None}
),
next_checkpoint,
{
"source": "fork",
"step": step + 1,
"parents": saved.metadata.get("parents", {}),
},
{},
)
# we want to both clone a checkpoint and update state in one go.
# reuse the same task ID if possible.
if isinstance(values, list) and len(values) > 0:
# figure out the task IDs for the next update checkpoint
next_tasks = prepare_next_tasks(
next_checkpoint,
saved.pending_writes or [],
self.nodes,
channels,
managed,
next_config,
step + 2,
step + 4,
for_execution=True,
store=self.store,
checkpointer=checkpointer,
manager=None,
)
tasks_group_by = defaultdict(list)
user_group_by: dict[str, list[StateUpdate]] = defaultdict(list)
for task in next_tasks.values():
tasks_group_by[task.name].append(task.id)
for item in values:
if not isinstance(item, Sequence):
raise InvalidUpdateError(
f"Invalid update item: {item} when copying checkpoint"
)
values, as_node = item[:2]
user_group = user_group_by[as_node]
tasks_group = tasks_group_by[as_node]
target_idx = len(user_group)
task_id = (
tasks_group[target_idx]
if target_idx < len(tasks_group)
else None
)
user_group_by[as_node].append(
StateUpdate(values=values, as_node=as_node, task_id=task_id)
)
return await aperform_superstep(
patch_checkpoint_map(next_config, saved.metadata),
[item for lst in user_group_by.values() for item in lst],
)
return patch_checkpoint_map(
next_config, saved.metadata if saved else None
)
# apply pending writes, if not on specific checkpoint
if (
CONFIG_KEY_CHECKPOINT_ID not in config[CONF]
and saved is not None
and saved.pending_writes
):
# tasks for this checkpoint
next_tasks = prepare_next_tasks(
checkpoint,
saved.pending_writes,
self.nodes,
channels,
managed,
saved.config,
step + 1,
step + 3,
for_execution=True,
store=self.store,
checkpointer=checkpointer,
manager=None,
)
# apply null writes
if null_writes := [
w[1:] for w in saved.pending_writes or [] if w[0] == NULL_TASK_ID
]:
apply_writes(
checkpoint,
channels,
[PregelTaskWrites((), INPUT, null_writes, [])],
checkpointer.get_next_version,
self.trigger_to_nodes,
)
for tid, k, v in saved.pending_writes:
if k in (ERROR, INTERRUPT):
continue
if tid not in next_tasks:
continue
next_tasks[tid].writes.append((k, v))
if tasks := [t for t in next_tasks.values() if t.writes]:
apply_writes(
checkpoint,
channels,
tasks,
checkpointer.get_next_version,
self.trigger_to_nodes,
)
valid_updates: list[tuple[str, dict[str, Any] | None, str | None]] = []
if len(updates) == 1:
values, as_node, task_id = updates[0]
# find last node that updated the state, if not provided
if as_node is None and len(self.nodes) == 1:
as_node = tuple(self.nodes)[0]
elif as_node is None and not saved:
if (
isinstance(self.input_channels, str)
and self.input_channels in self.nodes
):
as_node = self.input_channels
elif as_node is None:
last_seen_by_node = sorted(
(v, n)
for n, seen in checkpoint["versions_seen"].items()
if n in self.nodes
for v in seen.values()
)
# if two nodes updated the state at the same time, it's ambiguous
if last_seen_by_node:
if len(last_seen_by_node) == 1:
as_node = last_seen_by_node[0][1]
elif last_seen_by_node[-1][0] != last_seen_by_node[-2][0]:
as_node = last_seen_by_node[-1][1]
if as_node is None:
raise InvalidUpdateError("Ambiguous update, specify as_node")
if as_node not in self.nodes:
raise InvalidUpdateError(f"Node {as_node} does not exist")
valid_updates.append((as_node, values, task_id))
else:
for values, as_node, task_id in updates:
if as_node is None:
raise InvalidUpdateError(
"as_node is required when applying multiple updates"
)
if as_node not in self.nodes:
raise InvalidUpdateError(f"Node {as_node} does not exist")
valid_updates.append((as_node, values, task_id))
run_tasks: list[PregelTaskWrites] = []
run_task_ids: list[str] = []
for as_node, values, provided_task_id in valid_updates:
# create task to run all writers of the chosen node
writers = self.nodes[as_node].flat_writers
if not writers:
raise InvalidUpdateError(f"Node {as_node} has no writers")
writes: deque[tuple[str, Any]] = deque()
task = PregelTaskWrites((), as_node, writes, [INTERRUPT])
task_id = provided_task_id or str(
uuid5(UUID(checkpoint["id"]), INTERRUPT)
)
run_tasks.append(task)
run_task_ids.append(task_id)
run = RunnableSequence(*writers) if len(writers) > 1 else writers[0]
# execute task
await run.ainvoke(
values,
patch_config(
config,
run_name=self.name + "UpdateState",
configurable={
# deque.extend is thread-safe
CONFIG_KEY_SEND: writes.extend,
CONFIG_KEY_TASK_ID: task_id,
CONFIG_KEY_READ: partial(
local_read,
_scratchpad(
None,
[],
task_id,
"",
None,
step,
step + 2,
),
channels,
managed,
task,
),
},
),
)
# save task writes
for task_id, task in zip(run_task_ids, run_tasks):
# channel writes are saved to current checkpoint
channel_writes = [w for w in task.writes if w[0] != PUSH]
if saved and channel_writes:
await checkpointer.aput_writes(
checkpoint_config, channel_writes, task_id
)
# apply to checkpoint and save
apply_writes(
checkpoint,
channels,
run_tasks,
checkpointer.get_next_version,
self.trigger_to_nodes,
)
checkpoint = create_checkpoint(checkpoint, channels, step + 1)
# save checkpoint, after applying writes
next_config = await checkpointer.aput(
checkpoint_config,
checkpoint,
{
"source": "update",
"step": step + 1,
"parents": saved.metadata.get("parents", {}) if saved else {},
},
get_new_channel_versions(
checkpoint_previous_versions, checkpoint["channel_versions"]
),
)
for task_id, task in zip(run_task_ids, run_tasks):
# save push writes
if push_writes := [w for w in task.writes if w[0] == PUSH]:
await checkpointer.aput_writes(next_config, push_writes, task_id)
return patch_checkpoint_map(next_config, saved.metadata if saved else None)
current_config = patch_configurable(
config, {CONFIG_KEY_THREAD_ID: str(config[CONF][CONFIG_KEY_THREAD_ID])}
)
for superstep in supersteps:
current_config = await aperform_superstep(current_config, superstep)
return current_config
def update_state(
self,
config: RunnableConfig,
values: dict[str, Any] | Any | None,
as_node: str | None = None,
task_id: str | None = None,
) -> RunnableConfig:
"""Update the state of the graph with the given values, as if they came from
node `as_node`. If `as_node` is not provided, it will be set to the last node
that updated the state, if not ambiguous.
"""
return self.bulk_update_state(config, [[StateUpdate(values, as_node, task_id)]])
async def aupdate_state(
self,
config: RunnableConfig,
values: dict[str, Any] | Any,
as_node: str | None = None,
task_id: str | None = None,
) -> RunnableConfig:
"""Asynchronously update the state of the graph with the given values, as if they came from
node `as_node`. If `as_node` is not provided, it will be set to the last node
that updated the state, if not ambiguous.
"""
return await self.abulk_update_state(
config, [[StateUpdate(values, as_node, task_id)]]
)
def _defaults(
self,
config: RunnableConfig,
*,
stream_mode: StreamMode | Sequence[StreamMode],
print_mode: StreamMode | Sequence[StreamMode],
output_keys: str | Sequence[str] | None,
interrupt_before: All | Sequence[str] | None,
interrupt_after: All | Sequence[str] | None,
durability: Durability | None = None,
checkpoint_during: bool | None = None,
) -> tuple[
set[StreamMode],
str | Sequence[str],
All | Sequence[str],
All | Sequence[str],
BaseCheckpointSaver | None,
BaseStore | None,
BaseCache | None,
Durability,
]:
if config["recursion_limit"] < 1:
raise ValueError("recursion_limit must be at least 1")
if output_keys is None:
output_keys = self.stream_channels_asis
else:
validate_keys(output_keys, self.channels)
interrupt_before = interrupt_before or self.interrupt_before_nodes
interrupt_after = interrupt_after or self.interrupt_after_nodes
if not isinstance(stream_mode, list):
stream_modes = {stream_mode}
else:
stream_modes = set(stream_mode)
if isinstance(print_mode, str):
stream_modes.add(print_mode)
else:
stream_modes.update(print_mode)
if self.checkpointer is False:
checkpointer: BaseCheckpointSaver | None = None
elif CONFIG_KEY_CHECKPOINTER in config.get(CONF, {}):
checkpointer = config[CONF][CONFIG_KEY_CHECKPOINTER]
elif self.checkpointer is True:
raise RuntimeError("checkpointer=True cannot be used for root graphs.")
else:
checkpointer = self.checkpointer
if checkpointer and not config.get(CONF):
raise ValueError(
"Checkpointer requires one or more of the following 'configurable' "
"keys: thread_id, checkpoint_ns, checkpoint_id"
)
if CONFIG_KEY_RUNTIME in config.get(CONF, {}):
store: BaseStore | None = config[CONF][CONFIG_KEY_RUNTIME].store
else:
store = self.store
if CONFIG_KEY_CACHE in config.get(CONF, {}):
cache: BaseCache | None = config[CONF][CONFIG_KEY_CACHE]
else:
cache = self.cache
if checkpoint_during is not None:
if durability is not None:
raise ValueError(
"Cannot use both `checkpoint_during` and `durability` parameters."
)
elif checkpoint_during:
durability = "async"
else:
durability = "exit"
if durability is None:
durability = config.get(CONF, {}).get(CONFIG_KEY_DURABILITY, "async")
return (
stream_modes,
output_keys,
interrupt_before,
interrupt_after,
checkpointer,
store,
cache,
durability,
)
def stream(
self,
input: InputT | Command | None,
config: RunnableConfig | None = None,
*,
context: ContextT | None = None,
stream_mode: StreamMode | Sequence[StreamMode] | None = None,
print_mode: StreamMode | Sequence[StreamMode] = (),
output_keys: str | Sequence[str] | None = None,
interrupt_before: All | Sequence[str] | None = None,
interrupt_after: All | Sequence[str] | None = None,
durability: Durability | None = None,
subgraphs: bool = False,
debug: bool | None = None,
**kwargs: Unpack[DeprecatedKwargs],
) -> Iterator[dict[str, Any] | Any]:
"""Stream graph steps for a single input.
Args:
input: The input to the graph.
config: The configuration to use for the run.
context: The static context to use for the run.
!!! version-added "Added in version 0.6.0."
stream_mode: The mode to stream output, defaults to `self.stream_mode`.
Options are:
- `"values"`: Emit all values in the state after each step, including interrupts.
When used with functional API, values are emitted once at the end of the workflow.
- `"updates"`: Emit only the node or task names and updates returned by the nodes or tasks after each step.
If multiple updates are made in the same step (e.g. multiple nodes are run) then those updates are emitted separately.
- `"custom"`: Emit custom data from inside nodes or tasks using `StreamWriter`.
- `"messages"`: Emit LLM messages token-by-token together with metadata for any LLM invocations inside nodes or tasks.
Will be emitted as 2-tuples `(LLM token, metadata)`.
- `"checkpoints"`: Emit an event when a checkpoint is created, in the same format as returned by get_state().
- `"tasks"`: Emit events when tasks start and finish, including their results and errors.
You can pass a list as the `stream_mode` parameter to stream multiple modes at once.
The streamed outputs will be tuples of `(mode, data)`.
See [LangGraph streaming guide](https://langchain-ai.github.io/langgraph/how-tos/streaming/) for more details.
print_mode: Accepts the same values as `stream_mode`, but only prints the output to the console, for debugging purposes. Does not affect the output of the graph in any way.
output_keys: The keys to stream, defaults to all non-context channels.
interrupt_before: Nodes to interrupt before, defaults to all nodes in the graph.
interrupt_after: Nodes to interrupt after, defaults to all nodes in the graph.
durability: The durability mode for the graph execution, defaults to "async". Options are:
- `"sync"`: Changes are persisted synchronously before the next step starts.
- `"async"`: Changes are persisted asynchronously while the next step executes.
- `"exit"`: Changes are persisted only when the graph exits.
subgraphs: Whether to stream events from inside subgraphs, defaults to False.
If True, the events will be emitted as tuples `(namespace, data)`,
or `(namespace, mode, data)` if `stream_mode` is a list,
where `namespace` is a tuple with the path to the node where a subgraph is invoked,
e.g. `("parent_node:<task_id>", "child_node:<task_id>")`.
See [LangGraph streaming guide](https://langchain-ai.github.io/langgraph/how-tos/streaming/) for more details.
Yields:
The output of each step in the graph. The output shape depends on the stream_mode.
"""
if stream_mode is None:
# if being called as a node in another graph, default to values mode
# but don't overwrite stream_mode arg if provided
stream_mode = (
"values"
if config is not None and CONFIG_KEY_TASK_ID in config.get(CONF, {})
else self.stream_mode
)
if debug or self.debug:
print_mode = ["updates", "values"]
stream = SyncQueue()
config = ensure_config(self.config, config)
callback_manager = get_callback_manager_for_config(config)
run_manager = callback_manager.on_chain_start(
None,
input,
name=config.get("run_name", self.get_name()),
run_id=config.get("run_id"),
)
try:
deprecated_checkpoint_during = cast(
Optional[bool], kwargs.get("checkpoint_during")
)
if deprecated_checkpoint_during is not None:
warnings.warn(
"`checkpoint_during` is deprecated and will be removed. Please use `durability` instead.",
category=LangGraphDeprecatedSinceV10,
)
# assign defaults
(
stream_modes,
output_keys,
interrupt_before_,
interrupt_after_,
checkpointer,
store,
cache,
durability_,
) = self._defaults(
config,
stream_mode=stream_mode,
print_mode=print_mode,
output_keys=output_keys,
interrupt_before=interrupt_before,
interrupt_after=interrupt_after,
durability=durability,
checkpoint_during=deprecated_checkpoint_during,
)
if checkpointer is None and (
durability is not None or deprecated_checkpoint_during is not None
):
warnings.warn(
"`durability` has no effect when no checkpointer is present.",
)
# set up subgraph checkpointing
if self.checkpointer is True:
ns = cast(str, config[CONF][CONFIG_KEY_CHECKPOINT_NS])
config[CONF][CONFIG_KEY_CHECKPOINT_NS] = recast_checkpoint_ns(ns)
# set up messages stream mode
if "messages" in stream_modes:
run_manager.inheritable_handlers.append(
StreamMessagesHandler(stream.put, subgraphs)
)
# set up custom stream mode
if "custom" in stream_modes:
def stream_writer(c: Any) -> None:
stream.put(
(
tuple(
get_config()[CONF][CONFIG_KEY_CHECKPOINT_NS].split(
NS_SEP
)[:-1]
),
"custom",
c,
)
)
elif CONFIG_KEY_STREAM in config[CONF]:
stream_writer = config[CONF][CONFIG_KEY_RUNTIME].stream_writer
else:
def stream_writer(c: Any) -> None:
pass
# set durability mode for subgraphs
if durability is not None or deprecated_checkpoint_during is not None:
config[CONF][CONFIG_KEY_DURABILITY] = durability_
runtime = Runtime(
context=_coerce_context(self.context_schema, context),
store=store,
stream_writer=stream_writer,
previous=None,
)
parent_runtime = config[CONF].get(CONFIG_KEY_RUNTIME, DEFAULT_RUNTIME)
runtime = parent_runtime.merge(runtime)
config[CONF][CONFIG_KEY_RUNTIME] = runtime
with SyncPregelLoop(
input,
stream=StreamProtocol(stream.put, stream_modes),
config=config,
store=store,
cache=cache,
checkpointer=checkpointer,
nodes=self.nodes,
specs=self.channels,
output_keys=output_keys,
input_keys=self.input_channels,
stream_keys=self.stream_channels_asis,
interrupt_before=interrupt_before_,
interrupt_after=interrupt_after_,
manager=run_manager,
durability=durability_,
trigger_to_nodes=self.trigger_to_nodes,
migrate_checkpoint=self._migrate_checkpoint,
retry_policy=self.retry_policy,
cache_policy=self.cache_policy,
) as loop:
# create runner
runner = PregelRunner(
submit=config[CONF].get(
CONFIG_KEY_RUNNER_SUBMIT, weakref.WeakMethod(loop.submit)
),
put_writes=weakref.WeakMethod(loop.put_writes),
node_finished=config[CONF].get(CONFIG_KEY_NODE_FINISHED),
)
# enable subgraph streaming
if subgraphs:
loop.config[CONF][CONFIG_KEY_STREAM] = loop.stream
# enable concurrent streaming
if (
self.stream_eager
or subgraphs
or "messages" in stream_modes
or "custom" in stream_modes
):
# we are careful to have a single waiter live at any one time
# because on exit we increment semaphore count by exactly 1
waiter: concurrent.futures.Future | None = None
# because sync futures cannot be cancelled, we instead
# release the stream semaphore on exit, which will cause
# a pending waiter to return immediately
loop.stack.callback(stream._count.release)
def get_waiter() -> concurrent.futures.Future[None]:
nonlocal waiter
if waiter is None or waiter.done():
waiter = loop.submit(stream.wait)
return waiter
else:
return waiter
else:
get_waiter = None # type: ignore[assignment]
# Similarly to Bulk Synchronous Parallel / Pregel model
# computation proceeds in steps, while there are channel updates.
# Channel updates from step N are only visible in step N+1
# channels are guaranteed to be immutable for the duration of the step,
# with channel updates applied only at the transition between steps.
while loop.tick():
for task in loop.match_cached_writes():
loop.output_writes(task.id, task.writes, cached=True)
for _ in runner.tick(
[t for t in loop.tasks.values() if not t.writes],
timeout=self.step_timeout,
get_waiter=get_waiter,
schedule_task=loop.accept_push,
):
# emit output
yield from _output(
stream_mode, print_mode, subgraphs, stream.get, queue.Empty
)
loop.after_tick()
# wait for checkpoint
if durability_ == "sync":
loop._put_checkpoint_fut.result()
# emit output
yield from _output(
stream_mode, print_mode, subgraphs, stream.get, queue.Empty
)
# handle exit
if loop.status == "out_of_steps":
msg = create_error_message(
message=(
f"Recursion limit of {config['recursion_limit']} reached "
"without hitting a stop condition. You can increase the "
"limit by setting the `recursion_limit` config key."
),
error_code=ErrorCode.GRAPH_RECURSION_LIMIT,
)
raise GraphRecursionError(msg)
# set final channel values as run output
run_manager.on_chain_end(loop.output)
except BaseException as e:
run_manager.on_chain_error(e)
raise
async def astream(
self,
input: InputT | Command | None,
config: RunnableConfig | None = None,
*,
context: ContextT | None = None,
stream_mode: StreamMode | Sequence[StreamMode] | None = None,
print_mode: StreamMode | Sequence[StreamMode] = (),
output_keys: str | Sequence[str] | None = None,
interrupt_before: All | Sequence[str] | None = None,
interrupt_after: All | Sequence[str] | None = None,
durability: Durability | None = None,
subgraphs: bool = False,
debug: bool | None = None,
**kwargs: Unpack[DeprecatedKwargs],
) -> AsyncIterator[dict[str, Any] | Any]:
"""Asynchronously stream graph steps for a single input.
Args:
input: The input to the graph.
config: The configuration to use for the run.
context: The static context to use for the run.
!!! version-added "Added in version 0.6.0."
stream_mode: The mode to stream output, defaults to `self.stream_mode`.
Options are:
- `"values"`: Emit all values in the state after each step, including interrupts.
When used with functional API, values are emitted once at the end of the workflow.
- `"updates"`: Emit only the node or task names and updates returned by the nodes or tasks after each step.
If multiple updates are made in the same step (e.g. multiple nodes are run) then those updates are emitted separately.
- `"custom"`: Emit custom data from inside nodes or tasks using `StreamWriter`.
- `"messages"`: Emit LLM messages token-by-token together with metadata for any LLM invocations inside nodes or tasks.
Will be emitted as 2-tuples `(LLM token, metadata)`.
- `"debug"`: Emit debug events with as much information as possible for each step.
You can pass a list as the `stream_mode` parameter to stream multiple modes at once.
The streamed outputs will be tuples of `(mode, data)`.
See [LangGraph streaming guide](https://langchain-ai.github.io/langgraph/how-tos/streaming/) for more details.
print_mode: Accepts the same values as `stream_mode`, but only prints the output to the console, for debugging purposes. Does not affect the output of the graph in any way.
output_keys: The keys to stream, defaults to all non-context channels.
interrupt_before: Nodes to interrupt before, defaults to all nodes in the graph.
interrupt_after: Nodes to interrupt after, defaults to all nodes in the graph.
durability: The durability mode for the graph execution, defaults to "async". Options are:
- `"sync"`: Changes are persisted synchronously before the next step starts.
- `"async"`: Changes are persisted asynchronously while the next step executes.
- `"exit"`: Changes are persisted only when the graph exits.
subgraphs: Whether to stream events from inside subgraphs, defaults to False.
If True, the events will be emitted as tuples `(namespace, data)`,
or `(namespace, mode, data)` if `stream_mode` is a list,
where `namespace` is a tuple with the path to the node where a subgraph is invoked,
e.g. `("parent_node:<task_id>", "child_node:<task_id>")`.
See [LangGraph streaming guide](https://langchain-ai.github.io/langgraph/how-tos/streaming/) for more details.
Yields:
The output of each step in the graph. The output shape depends on the stream_mode.
"""
if stream_mode is None:
# if being called as a node in another graph, default to values mode
# but don't overwrite stream_mode arg if provided
stream_mode = (
"values"
if config is not None and CONFIG_KEY_TASK_ID in config.get(CONF, {})
else self.stream_mode
)
if debug or self.debug:
print_mode = ["updates", "values"]
stream = AsyncQueue()
aioloop = asyncio.get_running_loop()
stream_put = cast(
Callable[[StreamChunk], None],
partial(aioloop.call_soon_threadsafe, stream.put_nowait),
)
config = ensure_config(self.config, config)
callback_manager = get_async_callback_manager_for_config(config)
run_manager = await callback_manager.on_chain_start(
None,
input,
name=config.get("run_name", self.get_name()),
run_id=config.get("run_id"),
)
# if running from astream_log() run each proc with streaming
do_stream = (
next(
(
True
for h in run_manager.handlers
if isinstance(h, _StreamingCallbackHandler)
and not isinstance(h, StreamMessagesHandler)
),
False,
)
if _StreamingCallbackHandler is not None
else False
)
try:
deprecated_checkpoint_during = cast(
Optional[bool], kwargs.get("checkpoint_during")
)
if deprecated_checkpoint_during is not None:
warnings.warn(
"`checkpoint_during` is deprecated and will be removed. Please use `durability` instead.",
category=LangGraphDeprecatedSinceV10,
)
# assign defaults
(
stream_modes,
output_keys,
interrupt_before_,
interrupt_after_,
checkpointer,
store,
cache,
durability_,
) = self._defaults(
config,
stream_mode=stream_mode,
print_mode=print_mode,
output_keys=output_keys,
interrupt_before=interrupt_before,
interrupt_after=interrupt_after,
durability=durability,
checkpoint_during=deprecated_checkpoint_during,
)
if checkpointer is None and (
durability is not None or deprecated_checkpoint_during is not None
):
warnings.warn(
"`durability` has no effect when no checkpointer is present.",
)
# set up subgraph checkpointing
if self.checkpointer is True:
ns = cast(str, config[CONF][CONFIG_KEY_CHECKPOINT_NS])
config[CONF][CONFIG_KEY_CHECKPOINT_NS] = recast_checkpoint_ns(ns)
# set up messages stream mode
if "messages" in stream_modes:
run_manager.inheritable_handlers.append(
StreamMessagesHandler(stream_put, subgraphs)
)
# set up custom stream mode
def stream_writer(c: Any) -> None:
aioloop.call_soon_threadsafe(
stream.put_nowait,
(
tuple(
get_config()[CONF][CONFIG_KEY_CHECKPOINT_NS].split(NS_SEP)[
:-1
]
),
"custom",
c,
),
)
if "custom" in stream_modes:
def stream_writer(c: Any) -> None:
aioloop.call_soon_threadsafe(
stream.put_nowait,
(
tuple(
get_config()[CONF][CONFIG_KEY_CHECKPOINT_NS].split(
NS_SEP
)[:-1]
),
"custom",
c,
),
)
elif CONFIG_KEY_STREAM in config[CONF]:
stream_writer = config[CONF][CONFIG_KEY_RUNTIME].stream_writer
else:
def stream_writer(c: Any) -> None:
pass
# set durability mode for subgraphs
if durability is not None or deprecated_checkpoint_during is not None:
config[CONF][CONFIG_KEY_DURABILITY] = durability_
runtime = Runtime(
context=_coerce_context(self.context_schema, context),
store=store,
stream_writer=stream_writer,
previous=None,
)
parent_runtime = config[CONF].get(CONFIG_KEY_RUNTIME, DEFAULT_RUNTIME)
runtime = parent_runtime.merge(runtime)
config[CONF][CONFIG_KEY_RUNTIME] = runtime
async with AsyncPregelLoop(
input,
stream=StreamProtocol(stream.put_nowait, stream_modes),
config=config,
store=store,
cache=cache,
checkpointer=checkpointer,
nodes=self.nodes,
specs=self.channels,
output_keys=output_keys,
input_keys=self.input_channels,
stream_keys=self.stream_channels_asis,
interrupt_before=interrupt_before_,
interrupt_after=interrupt_after_,
manager=run_manager,
durability=durability_,
trigger_to_nodes=self.trigger_to_nodes,
migrate_checkpoint=self._migrate_checkpoint,
retry_policy=self.retry_policy,
cache_policy=self.cache_policy,
) as loop:
# create runner
runner = PregelRunner(
submit=config[CONF].get(
CONFIG_KEY_RUNNER_SUBMIT, weakref.WeakMethod(loop.submit)
),
put_writes=weakref.WeakMethod(loop.put_writes),
use_astream=do_stream,
node_finished=config[CONF].get(CONFIG_KEY_NODE_FINISHED),
)
# enable subgraph streaming
if subgraphs:
loop.config[CONF][CONFIG_KEY_STREAM] = StreamProtocol(
stream_put, stream_modes
)
# enable concurrent streaming
if (
self.stream_eager
or subgraphs
or "messages" in stream_modes
or "custom" in stream_modes
):
def get_waiter() -> asyncio.Task[None]:
return aioloop.create_task(stream.wait())
else:
get_waiter = None # type: ignore[assignment]
# Similarly to Bulk Synchronous Parallel / Pregel model
# computation proceeds in steps, while there are channel updates
# channel updates from step N are only visible in step N+1
# channels are guaranteed to be immutable for the duration of the step,
# with channel updates applied only at the transition between steps
while loop.tick():
for task in await loop.amatch_cached_writes():
loop.output_writes(task.id, task.writes, cached=True)
async for _ in runner.atick(
[t for t in loop.tasks.values() if not t.writes],
timeout=self.step_timeout,
get_waiter=get_waiter,
schedule_task=loop.aaccept_push,
):
# emit output
for o in _output(
stream_mode,
print_mode,
subgraphs,
stream.get_nowait,
asyncio.QueueEmpty,
):
yield o
loop.after_tick()
# wait for checkpoint
if durability_ == "sync":
await cast(asyncio.Future, loop._put_checkpoint_fut)
# emit output
for o in _output(
stream_mode,
print_mode,
subgraphs,
stream.get_nowait,
asyncio.QueueEmpty,
):
yield o
# handle exit
if loop.status == "out_of_steps":
msg = create_error_message(
message=(
f"Recursion limit of {config['recursion_limit']} reached "
"without hitting a stop condition. You can increase the "
"limit by setting the `recursion_limit` config key."
),
error_code=ErrorCode.GRAPH_RECURSION_LIMIT,
)
raise GraphRecursionError(msg)
# set final channel values as run output
await run_manager.on_chain_end(loop.output)
except BaseException as e:
await asyncio.shield(run_manager.on_chain_error(e))
raise
def invoke(
self,
input: InputT | Command | None,
config: RunnableConfig | None = None,
*,
context: ContextT | None = None,
stream_mode: StreamMode = "values",
print_mode: StreamMode | Sequence[StreamMode] = (),
output_keys: str | Sequence[str] | None = None,
interrupt_before: All | Sequence[str] | None = None,
interrupt_after: All | Sequence[str] | None = None,
**kwargs: Any,
) -> dict[str, Any] | Any:
"""Run the graph with a single input and config.
Args:
input: The input data for the graph. It can be a dictionary or any other type.
config: Optional. The configuration for the graph run.
context: The static context to use for the run.
!!! version-added "Added in version 0.6.0."
stream_mode: Optional[str]. The stream mode for the graph run. Default is "values".
print_mode: Accepts the same values as `stream_mode`, but only prints the output to the console, for debugging purposes. Does not affect the output of the graph in any way.
output_keys: Optional. The output keys to retrieve from the graph run.
interrupt_before: Optional. The nodes to interrupt the graph run before.
interrupt_after: Optional. The nodes to interrupt the graph run after.
**kwargs: Additional keyword arguments to pass to the graph run.
Returns:
The output of the graph run. If stream_mode is "values", it returns the latest output.
If stream_mode is not "values", it returns a list of output chunks.
"""
output_keys = output_keys if output_keys is not None else self.output_channels
latest: dict[str, Any] | Any = None
chunks: list[dict[str, Any] | Any] = []
interrupts: list[Interrupt] = []
for chunk in self.stream(
input,
config,
context=context,
stream_mode=["updates", "values"]
if stream_mode == "values"
else stream_mode,
print_mode=print_mode,
output_keys=output_keys,
interrupt_before=interrupt_before,
interrupt_after=interrupt_after,
**kwargs,
):
if stream_mode == "values":
if len(chunk) == 2:
mode, payload = cast(tuple[StreamMode, Any], chunk)
else:
_, mode, payload = cast(
tuple[tuple[str, ...], StreamMode, Any], chunk
)
if (
mode == "updates"
and isinstance(payload, dict)
and (ints := payload.get(INTERRUPT)) is not None
):
interrupts.extend(ints)
elif mode == "values":
latest = payload
else:
chunks.append(chunk)
if stream_mode == "values":
if interrupts:
return (
{**latest, INTERRUPT: interrupts}
if isinstance(latest, dict)
else {INTERRUPT: interrupts}
)
return latest
else:
return chunks
async def ainvoke(
self,
input: InputT | Command | None,
config: RunnableConfig | None = None,
*,
context: ContextT | None = None,
stream_mode: StreamMode = "values",
print_mode: StreamMode | Sequence[StreamMode] = (),
output_keys: str | Sequence[str] | None = None,
interrupt_before: All | Sequence[str] | None = None,
interrupt_after: All | Sequence[str] | None = None,
**kwargs: Any,
) -> dict[str, Any] | Any:
"""Asynchronously invoke the graph on a single input.
Args:
input: The input data for the computation. It can be a dictionary or any other type.
config: Optional. The configuration for the computation.
context: The static context to use for the run.
!!! version-added "Added in version 0.6.0."
stream_mode: Optional. The stream mode for the computation. Default is "values".
print_mode: Accepts the same values as `stream_mode`, but only prints the output to the console, for debugging purposes. Does not affect the output of the graph in any way.
output_keys: Optional. The output keys to include in the result. Default is None.
interrupt_before: Optional. The nodes to interrupt before. Default is None.
interrupt_after: Optional. The nodes to interrupt after. Default is None.
**kwargs: Additional keyword arguments.
Returns:
The result of the computation. If stream_mode is "values", it returns the latest value.
If stream_mode is "chunks", it returns a list of chunks.
"""
output_keys = output_keys if output_keys is not None else self.output_channels
latest: dict[str, Any] | Any = None
chunks: list[dict[str, Any] | Any] = []
interrupts: list[Interrupt] = []
async for chunk in self.astream(
input,
config,
context=context,
stream_mode=["updates", "values"]
if stream_mode == "values"
else stream_mode,
print_mode=print_mode,
output_keys=output_keys,
interrupt_before=interrupt_before,
interrupt_after=interrupt_after,
**kwargs,
):
if stream_mode == "values":
if len(chunk) == 2:
mode, payload = cast(tuple[StreamMode, Any], chunk)
else:
_, mode, payload = cast(
tuple[tuple[str, ...], StreamMode, Any], chunk
)
if (
mode == "updates"
and isinstance(payload, dict)
and (ints := payload.get(INTERRUPT)) is not None
):
interrupts.extend(ints)
elif mode == "values":
latest = payload
else:
chunks.append(chunk)
if stream_mode == "values":
if interrupts:
return (
{**latest, INTERRUPT: interrupts}
if isinstance(latest, dict)
else {INTERRUPT: interrupts}
)
return latest
else:
return chunks
def clear_cache(self, nodes: Sequence[str] | None = None) -> None:
"""Clear the cache for the given nodes."""
if not self.cache:
raise ValueError("No cache is set for this graph. Cannot clear cache.")
nodes = nodes or self.nodes.keys()
# collect namespaces to clear
namespaces: list[tuple[str, ...]] = []
for node in nodes:
if node in self.nodes:
namespaces.append(
(
CACHE_NS_WRITES,
(identifier(self.nodes[node]) or "__dynamic__"),
node,
),
)
# clear cache
self.cache.clear(namespaces)
async def aclear_cache(self, nodes: Sequence[str] | None = None) -> None:
"""Asynchronously clear the cache for the given nodes."""
if not self.cache:
raise ValueError("No cache is set for this graph. Cannot clear cache.")
nodes = nodes or self.nodes.keys()
# collect namespaces to clear
namespaces: list[tuple[str, ...]] = []
for node in nodes:
if node in self.nodes:
namespaces.append(
(
CACHE_NS_WRITES,
(identifier(self.nodes[node]) or "__dynamic__"),
node,
),
)
# clear cache
await self.cache.aclear(namespaces)
def _trigger_to_nodes(nodes: dict[str, PregelNode]) -> Mapping[str, Sequence[str]]:
"""Index from a trigger to nodes that depend on it."""
trigger_to_nodes: defaultdict[str, list[str]] = defaultdict(list)
for name, node in nodes.items():
for trigger in node.triggers:
trigger_to_nodes[trigger].append(name)
return dict(trigger_to_nodes)
def _output(
stream_mode: StreamMode | Sequence[StreamMode],
print_mode: StreamMode | Sequence[StreamMode],
stream_subgraphs: bool,
getter: Callable[[], tuple[tuple[str, ...], str, Any]],
empty_exc: type[Exception],
) -> Iterator:
while True:
try:
ns, mode, payload = getter()
except empty_exc:
break
if mode in print_mode:
if stream_subgraphs and ns:
print(
" ".join(
(
get_bolded_text(f"[{mode}]"),
get_colored_text(f"[graph={ns}]", color="yellow"),
repr(payload),
)
)
)
else:
print(
" ".join(
(
get_bolded_text(f"[{mode}]"),
repr(payload),
)
)
)
if mode in stream_mode:
if stream_subgraphs and isinstance(stream_mode, list):
yield (ns, mode, payload)
elif isinstance(stream_mode, list):
yield (mode, payload)
elif stream_subgraphs:
yield (ns, payload)
else:
yield payload
def _coerce_context(
context_schema: type[ContextT] | None, context: Any
) -> ContextT | None:
"""Coerce context input to the appropriate schema type.
If context is a dict and context_schema is a dataclass or pydantic model, we coerce.
Else, we return the context as-is.
Args:
context_schema: The schema type to coerce to (BaseModel, dataclass, or TypedDict)
context: The context value to coerce
Returns:
The coerced context value or None if context is None
"""
if context is None:
return None
if context_schema is None:
return context
schema_is_class = issubclass(context_schema, BaseModel) or is_dataclass(
context_schema
)
if isinstance(context, dict) and schema_is_class:
return context_schema(**context) # type: ignore[misc]
return cast(ContextT, context)
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