sglang quant module remove vllm dependency (#4507)

python/sglang/srt/layers/quantization/gptq.py

@@ -3,11 +3,21 @@ from fractions import Fraction
 from typing import Any, Dict, List, Optional, Union
 
 import torch
-from vllm.scalar_type import scalar_types
 
 from sglang.srt.layers.linear import LinearBase
 from sglang.srt.layers.quantization.base_config import QuantizationConfig
+from sglang.srt.layers.quantization.utils import scalar_types
 from sglang.srt.layers.vocab_parallel_embedding import ParallelLMHead
+from sglang.srt.utils import is_cuda
+
+_is_cuda = is_cuda()
+
+try:
+    import vllm
+
+    VLLM_AVAILABLE = True
+except ImportError:
+    VLLM_AVAILABLE = False
 
 logger = logging.getLogger(__name__)
 
@@ -110,6 +120,9 @@ class GPTQConfig(QuantizationConfig):
     def get_quant_method(
         self, layer: torch.nn.Module, prefix: str
     ) -> Optional["GPTQLinearMethod"]:
+        if not VLLM_AVAILABLE:
+            raise ImportError("vllm is not installed")
+
         from vllm.model_executor.layers.quantization.gptq import GPTQLinearMethod
 
         from sglang.srt.layers.quantization import get_linear_quant_method
@@ -263,6 +276,9 @@ class GPTQMarlinConfig(QuantizationConfig):
     def get_quant_method(
         self, layer: torch.nn.Module, prefix: str
     ) -> Optional["QuantizeMethodBase"]:
+        if not VLLM_AVAILABLE:
+            raise ImportError("vllm is not installed")
+
         from vllm.model_executor.layers.quantization.gptq_marlin import (
             GPTQMarlinLinearMethod,
             GPTQMarlinMoEMethod,
@@ -285,6 +301,9 @@ class GPTQMarlinConfig(QuantizationConfig):
 
     @classmethod
     def is_gptq_marlin_compatible(cls, quant_config: Dict[str, Any]):
+        if not VLLM_AVAILABLE:
+            return False
+
         quant_method = quant_config.get("quant_method", "").lower()
         num_bits = quant_config.get("bits")
         group_size = quant_config.get("group_size")
@@ -294,9 +313,8 @@ class GPTQMarlinConfig(QuantizationConfig):
         from vllm.model_executor.layers.quantization.utils.marlin_utils import (
             check_marlin_supported,
         )
-        from vllm.platforms import current_platform
 
-        if not current_platform.is_cuda():
+        if not _is_cuda:
             return False
 
         if quant_method != "gptq":
@@ -407,6 +425,9 @@ class MarlinConfig(QuantizationConfig):
     def get_quant_method(
         self, layer: torch.nn.Module, prefix: str
     ) -> Optional["MarlinLinearMethod"]:
+        if not VLLM_AVAILABLE:
+            raise ImportError("vllm is not installed")
+
         from vllm.model_executor.layers.quantization.marlin import MarlinLinearMethod
 
         if isinstance(layer, LinearBase) or (