[PluggableLayer][MM] Add PluggableLayer for CustomQwen2Decoder (vllm-project#37293)

Signed-off-by: Wangbei25 <wangbei41@huawie.com>
Signed-off-by: Wangbei25 <wangbei41@huawei.com>
Co-authored-by: Wangbei25 <wangbei41@huawie.com>

Author: Wangbei25

docs/design/custom_op.md

@@ -51,11 +51,8 @@ For example:
 **1. Attention:**
 
 ```python
---8<-- "vllm/model_executor/layers/attention/mm_encoder_attention.py:mm_encoder_attn"
-
 --8<-- "vllm/model_executor/layers/mla.py:multi_head_latent_attention"
 
---8<-- "vllm/model_executor/models/deepencoder.py:rel_pos_attention"
 ```
 
 **2. Activation:**
@@ -170,6 +167,16 @@ For example:
 --8<-- "vllm/model_executor/layers/rotary_embedding/common.py:apply_rotary_emb"
 ```
 
+**12. Encoder:**
+
+```python
+--8<-- "vllm/model_executor/models/deepencoder2.py:qwen2_decoder"
+
+--8<-- "vllm/model_executor/layers/attention/mm_encoder_attention.py:mm_encoder_attn"
+
+--8<-- "vllm/model_executor/models/deepencoder.py:rel_pos_attention"
+```
+
 ## Guidelines for Implementing a New CustomOp
 
 ### Implement a New CustomOp in vLLM

vllm/model_executor/models/deepencoder2.py

@@ -14,14 +14,20 @@
 import torch.nn as nn
 import transformers
 
+from vllm.model_executor.custom_op import PluggableLayer
 
-class CustomQwen2Decoder(nn.Module):
+
+# --8<-- [start:qwen2_decoder]
+@PluggableLayer.register("qwen2_decoder")
+class CustomQwen2Decoder(PluggableLayer):
     """
     Qwen2 visual encoder
     non-causal attention + causal attention
     token_type_ids ：0=non-causal, 1=causal
     """
 
+    # --8<-- [end:qwen2_decoder]
+
     def __init__(
         self,
         decoder_layer: int = 24,