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https://github.com/langchain-ai/langgraph.git
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Nuno Campos
52b2c755d7
- this avoids conflicts if multiple processes creating checkpoints in same thread at same time - uuid6 with a monotically increasing clock_seq is sortable by creation time at ms precision (plus clock_seq for ties, plus 48 bits of randomness for further ties)
49 lines
1.3 KiB
Python
49 lines
1.3 KiB
Python
from collections import defaultdict
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from typing import Any, Optional
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from langgraph.checkpoint.base import (
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Checkpoint,
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CheckpointMetadata,
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SerializerProtocol,
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copy_checkpoint,
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)
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from langgraph.checkpoint.memory import MemorySaver
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class NoopSerializer(SerializerProtocol):
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def loads(self, data: bytes) -> Any:
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return data
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def dumps(self, obj: Any) -> bytes:
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return obj
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class MemorySaverAssertImmutable(MemorySaver):
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serde = NoopSerializer()
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storage_for_copies: defaultdict[str, dict[str, Checkpoint]]
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def __init__(
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self,
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*,
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serde: Optional[SerializerProtocol] = None,
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) -> None:
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super().__init__(serde=serde)
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self.storage_for_copies = defaultdict(dict)
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def put(
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self,
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config: dict,
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checkpoint: Checkpoint,
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metadata: Optional[CheckpointMetadata] = None,
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) -> None:
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# assert checkpoint hasn't been modified since last written
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thread_id = config["configurable"]["thread_id"]
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if saved := super().get(config):
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assert self.storage_for_copies[thread_id][saved["id"]] == saved
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self.storage_for_copies[thread_id][checkpoint["id"]] = copy_checkpoint(
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checkpoint
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)
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# call super to write checkpoint
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return super().put(config, checkpoint, metadata)
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