chore: import upstream snapshot with attribution

vllm/model_executor/model_loader/modelexpress_loader.py

@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+from __future__ import annotations
+
+import importlib
+
+from torch import nn
+
+from vllm.config import ModelConfig, VllmConfig
+from vllm.config.load import LoadConfig
+from vllm.model_executor.model_loader.base_loader import BaseModelLoader
+from vllm.tracing import instrument
+
+_MODELEXPRESS_LOADER_MODULE = "modelexpress.engines.vllm.loader"
+_MISSING_MODELEXPRESS_MODULES = frozenset(
+    {
+        "modelexpress",
+        "modelexpress.engines",
+        "modelexpress.engines.vllm",
+        _MODELEXPRESS_LOADER_MODULE,
+    }
+)
+
+
+def _missing_modelexpress_error() -> ImportError:
+    return ImportError(
+        "The 'modelexpress' load format requires the ModelExpress Python package. "
+        "Install it with `pip install modelexpress`."
+    )
+
+
+class ModelExpressModelLoader(BaseModelLoader):
+    """Thin vLLM loader wrapper for ModelExpress."""
+
+    def __init__(self, load_config: LoadConfig):
+        super().__init__(load_config)
+        self._loader = self._load_modelexpress_loader(load_config)
+
+    @staticmethod
+    def _load_modelexpress_loader(load_config: LoadConfig) -> BaseModelLoader:
+        try:
+            module = importlib.import_module(_MODELEXPRESS_LOADER_MODULE)
+        except ModuleNotFoundError as exc:
+            if exc.name not in _MISSING_MODELEXPRESS_MODULES:
+                raise
+            raise _missing_modelexpress_error() from exc
+
+        ModelExpressVllmLoader = module.MxModelLoader
+        return ModelExpressVllmLoader(load_config)
+
+    def download_model(self, model_config: ModelConfig) -> None:
+        self._loader.download_model(model_config)
+
+    def load_weights(self, model: nn.Module, model_config: ModelConfig) -> None:
+        self._loader.load_weights(model, model_config)
+
+    @instrument(span_name="Load model")
+    def load_model(
+        self,
+        vllm_config: VllmConfig,
+        model_config: ModelConfig,
+        prefix: str = "",
+    ) -> nn.Module:
+        model = self._loader.load_model(
+            vllm_config=vllm_config,
+            model_config=model_config,
+            prefix=prefix,
+        )
+        return model.eval()