[Refactor] cache cos/sin in mla & remove parameter model in builder. (#5277)

RFC: https://github.com/vllm-project/vllm-ascend/issues/4629

1. Cache cos/sin in mla
2. AttentionBuilder inherits from the original class of vllm.



version: release/v0.13.0
- vLLM main:
ad32e3e19c

---------

Signed-off-by: weijinqian_v1 <weijinqian@huawei.com>
Co-authored-by: weijinqian_v1 <weijinqian@huawei.com>

tests/ut/attention/test_sfa_v1.py

@@ -1,5 +1,5 @@
 import sys
-from unittest.mock import MagicMock
+from unittest.mock import MagicMock, patch
 
 import torch
 from vllm.v1.attention.backends.utils import AttentionCGSupport
@@ -102,7 +102,8 @@ class TestAscendSFAMetadataBuilder(TestBase):
         assert builder.device == device
         assert builder.vllm_config == vllm_config
 
-    def test_ascend_sfa_metadata_builder_build(self):
+    @patch("vllm_ascend.attention.sfa_v1.get_cos_and_sin_mla")
+    def test_ascend_sfa_metadata_builder_build(self, mock_get_cos_and_sin_mla):
         kv_cache_spec = MagicMock()
         layer_names = ["layer1", "layer2"]
         vllm_config = MagicMock()
@@ -133,21 +134,21 @@ class TestAscendSFAMetadataBuilder(TestBase):
         common_attn_metadata.sin = None
         common_attn_metadata.num_input_tokens = 100
 
-        model = MagicMock()
-        model.model.layers = [MagicMock() for _ in range(10)]
-        model.model.start_layer = 0
+        mock_get_cos_and_sin_mla.return_value = (torch.randn(100),
+                                                 torch.randn(100))
 
         metadata = builder.build(
             common_prefix_len=10,
             common_attn_metadata=common_attn_metadata,
-            model=model,
         )
 
         assert isinstance(metadata, AscendSFAMetadata)
         assert metadata.num_actual_tokens == common_attn_metadata.num_actual_tokens
         assert metadata.slot_mapping.shape == (100, 4, 1024)
 
-    def test_ascend_sfa_metadata_builder_build_for_graph_capture(self):
+    @patch("vllm_ascend.attention.sfa_v1.get_cos_and_sin_mla")
+    def test_ascend_sfa_metadata_builder_build_for_graph_capture(
+            self, mock_get_cos_and_sin_mla):
         kv_cache_spec = MagicMock()
         layer_names = ["layer1", "layer2"]
         vllm_config = MagicMock()
@@ -178,14 +179,12 @@ class TestAscendSFAMetadataBuilder(TestBase):
         common_attn_metadata.sin = None
         common_attn_metadata.num_input_tokens = 100
 
-        model = MagicMock()
-        model.model.layers = [MagicMock() for _ in range(10)]
-        model.model.start_layer = 0
+        mock_get_cos_and_sin_mla.return_value = (torch.randn(100),
+                                                 torch.randn(100))
 
         attn_metadata = builder.build_for_graph_capture(
             common_attn_metadata=common_attn_metadata,
             attn_state=AscendAttentionState.DecodeOnly,
-            model=model,
         )
 
         assert isinstance(attn_metadata, AscendSFAMetadata)