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vllm-omni/vllm_omni/distributed/omni_connectors/utils/serialization.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from dataclasses import asdict, is_dataclass
from typing import Any
import msgspec
import numpy as np
import torch
from msgspec import msgpack
from PIL import Image
from vllm.outputs import CompletionOutput, RequestOutput
# Type markers for custom serialization
_TENSOR_MARKER = "__tensor__"
_NDARRAY_MARKER = "__ndarray__"
_PIL_IMAGE_MARKER = "__pil_image__"
# Keys that identify a RequestOutput dict (for reconstruction)
_REQUEST_OUTPUT_KEYS = frozenset({"request_id", "prompt", "prompt_token_ids", "outputs", "finished"})
# Keys that identify a CompletionOutput dict (for reconstruction)
_COMPLETION_OUTPUT_KEYS = frozenset({"index", "text", "token_ids", "finish_reason"})
class OmniMsgpackEncoder:
"""
This implementation is adapted from vLLM’s MsgpackEncoder.
However, zero-copy support has not been implemented yet.
Handles torch.Tensor, numpy.ndarray, PIL.Image, RequestOutput and
CompletionOutput by converting them to serializable dict representations.
TODO: Enable zero-copy support.
"""
def __init__(self):
self.encoder = msgpack.Encoder(enc_hook=self._enc_hook)
def encode(self, obj: Any) -> bytes:
"""Encode an object to bytes."""
return self.encoder.encode(obj)
def _enc_hook(self, obj: Any) -> Any:
"""Custom encoding hook for non-standard types."""
# torch.Tensor
if isinstance(obj, torch.Tensor):
return self._encode_tensor(obj)
# numpy.ndarray (exclude object/void dtypes)
if isinstance(obj, np.ndarray) and obj.dtype.kind not in ("O", "V"):
return self._encode_ndarray(obj)
# PIL.Image
if isinstance(obj, Image.Image):
return self._encode_pil_image(obj)
# RequestOutput (not a dataclass, needs special handling)
if isinstance(obj, RequestOutput):
return self._encode_request_output(obj)
# CompletionOutput (dataclass)
if isinstance(obj, CompletionOutput):
return self._encode_completion_output(obj)
# Other dataclasses
if is_dataclass(obj) and not isinstance(obj, type):
return asdict(obj)
# slice
if isinstance(obj, slice):
return (obj.start, obj.stop, obj.step)
raise TypeError(
f"Object of type {type(obj).__name__} is not serializable. "
"Supported types: torch.Tensor, np.ndarray, PIL.Image, dataclass, "
"RequestOutput, and standard Python types (dict, list, str, int, float, bool, None, bytes)."
)
def _encode_tensor(self, tensor: torch.Tensor) -> dict[str, Any]:
"""Encode torch.Tensor to dict."""
t = tensor.detach().contiguous().cpu().view(torch.uint8)
return {
_TENSOR_MARKER: True,
"dtype": str(tensor.dtype).removeprefix("torch."),
"shape": list(tensor.shape),
"data": t.numpy().tobytes(),
}
def _encode_ndarray(self, arr: np.ndarray) -> dict[str, Any]:
"""Encode numpy.ndarray to dict."""
if not arr.flags.c_contiguous:
arr = np.ascontiguousarray(arr)
return {
_NDARRAY_MARKER: True,
"dtype": arr.dtype.str,
"shape": list(arr.shape),
"data": arr.tobytes(),
}
def _encode_pil_image(self, img: Image.Image) -> dict[str, Any]:
"""Encode PIL.Image to dict."""
arr = np.asarray(img, dtype=np.uint8)
if not arr.flags.c_contiguous:
arr = np.ascontiguousarray(arr)
return {
_PIL_IMAGE_MARKER: True,
"mode": img.mode,
"shape": list(arr.shape),
"data": arr.tobytes(),
}
def _encode_request_output(self, obj: RequestOutput) -> dict[str, Any]:
"""Encode RequestOutput to dict.
RequestOutput is not a dataclass, so we manually extract its attributes.
Also handles dynamically added 'multimodal_output' attribute.
"""
# msgspec can serialize CompletionOutput dataclasses directly, but it
# drops dynamic fields such as multimodal_output. Encode them manually
# to preserve multimodal payloads across IPC.
encoded_outputs = []
for o in obj.outputs:
if isinstance(o, CompletionOutput):
encoded_outputs.append(self._encode_completion_output(o))
else:
encoded_outputs.append(o)
result = {
"request_id": obj.request_id,
"prompt": obj.prompt,
"prompt_token_ids": obj.prompt_token_ids,
"prompt_logprobs": obj.prompt_logprobs,
"outputs": encoded_outputs,
"finished": obj.finished,
"metrics": obj.metrics,
"lora_request": obj.lora_request,
"encoder_prompt": obj.encoder_prompt,
"encoder_prompt_token_ids": obj.encoder_prompt_token_ids,
"num_cached_tokens": obj.num_cached_tokens,
"multi_modal_placeholders": obj.multi_modal_placeholders,
"kv_transfer_params": obj.kv_transfer_params,
}
# Handle dynamically added multimodal_output attribute
mm_output = getattr(obj, "multimodal_output", None)
if mm_output is not None:
result["multimodal_output"] = mm_output
return result
def _encode_completion_output(self, obj: CompletionOutput) -> dict[str, Any]:
"""Encode CompletionOutput to dict, preserving multimodal payloads."""
result = asdict(obj)
mm_output = getattr(obj, "multimodal_output", None)
if mm_output is not None:
result["multimodal_output"] = mm_output
return result
class OmniMsgpackDecoder:
"""
This implementation is adapted from vLLM’s MsgpackDecoder.
However, zero-copy support has not been implemented yet.
Automatically reconstructs torch.Tensor, numpy.ndarray, PIL.Image,
RequestOutput and CompletionOutput from their dict representations.
TODO: Enable zero-copy support.
"""
def __init__(self):
self.decoder = msgpack.Decoder()
def decode(self, data: bytes | bytearray | memoryview) -> Any:
"""Decode bytes to object."""
result = self.decoder.decode(data)
return self._post_process(result)
def _post_process(self, obj: Any) -> Any:
"""Recursively restore tensor/ndarray/image/RequestOutput from their dict representations."""
if isinstance(obj, dict):
# Check for type markers first
if obj.get(_TENSOR_MARKER):
return self._decode_tensor(obj)
if obj.get(_NDARRAY_MARKER):
return self._decode_ndarray(obj)
if obj.get(_PIL_IMAGE_MARKER):
return self._decode_pil_image(obj)
# Process values recursively first
processed = {k: self._post_process(v) for k, v in obj.items()}
# Check if this looks like a RequestOutput
if _REQUEST_OUTPUT_KEYS.issubset(processed.keys()):
return self._decode_request_output(processed)
# Check if this looks like a CompletionOutput
if _COMPLETION_OUTPUT_KEYS.issubset(processed.keys()):
return self._decode_completion_output(processed)
return processed
if isinstance(obj, list):
return [self._post_process(item) for item in obj]
if isinstance(obj, tuple):
return tuple(self._post_process(item) for item in obj)
return obj
def _decode_tensor(self, obj: dict[str, Any]) -> torch.Tensor:
"""Decode dict to torch.Tensor."""
dtype_str = obj["dtype"]
shape = obj["shape"]
data = obj["data"]
torch_dtype = getattr(torch, dtype_str)
if not data:
return torch.empty(shape, dtype=torch_dtype)
buffer = bytearray(data) if isinstance(data, (bytes, memoryview)) else data
arr = torch.frombuffer(buffer, dtype=torch.uint8)
return arr.view(torch_dtype).reshape(shape)
def _decode_ndarray(self, obj: dict[str, Any]) -> np.ndarray:
"""Decode dict to numpy.ndarray."""
dtype = obj["dtype"]
shape = obj["shape"]
data = obj["data"]
return np.frombuffer(data, dtype=dtype).reshape(shape)
def _decode_pil_image(self, obj: dict[str, Any]) -> Image.Image:
"""Decode dict to PIL.Image."""
mode = obj["mode"]
shape = obj["shape"]
data = obj["data"]
arr = np.frombuffer(data, dtype=np.uint8).reshape(shape)
return Image.fromarray(arr, mode=mode)
def _decode_completion_output(self, obj: dict[str, Any]) -> CompletionOutput:
"""Decode dict to CompletionOutput using msgspec.convert."""
mm_output = obj.pop("multimodal_output", None)
co = msgspec.convert(obj, CompletionOutput)
if mm_output is not None:
setattr(co, "multimodal_output", mm_output)
return co
def _decode_request_output(self, obj: dict[str, Any]) -> RequestOutput:
"""Decode dict to RequestOutput.
RequestOutput is not a dataclass, so msgspec.convert doesn't work.
We construct it manually, passing all known fields via **kwargs.
"""
# Extract multimodal_output before constructing (it's dynamically added)
mm_output = obj.pop("multimodal_output", None)
# RequestOutput.__init__ accepts **kwargs for forward compatibility
ro = RequestOutput(**obj)
# Restore dynamically added multimodal_output attribute
if mm_output is not None:
setattr(ro, "multimodal_output", mm_output)
return ro
class OmniSerde:
"""Serialization/deserialization handler for Omni IPC."""
def __init__(self):
self.encoder = OmniMsgpackEncoder()
self.decoder = OmniMsgpackDecoder()
def serialize(self, obj: Any) -> bytes:
"""Serialize an object to bytes."""
return self.encoder.encode(obj)
def deserialize(self, data: bytes | bytearray | memoryview) -> Any:
"""Deserialize bytes to an object."""
return self.decoder.decode(data)
# Global instance for simple interface
OmniSerializer = OmniSerde()