[feature] chunkprefill support pcp&dcp (#3801)

### What this PR does / why we need it?
ChunkPrefill now can support Long Sequence Feature Pcp&Dcp

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
CI tests passed with self-test


- vLLM version: v0.11.0
- vLLM main:
83f478bb19

---------

Signed-off-by: Apocalypse990923-qshi <qiushixu@usc.edu>
Signed-off-by: Delphine-Nic <tanwenqin@huawei.com>
Co-authored-by: Delphine-Nic <tanwenqin@huawei.com>
Co-authored-by: Delphine-Nic <3834144971@qq.com>

vllm_ascend/worker/npu_input_batch.py

@@ -73,6 +73,12 @@ class CachedRequestState:
     lora_request: Optional[LoRARequest] = None
     prompt_embeds: Optional[torch.Tensor] = None
 
+    # pcp/dcp param
+    local_chunked_kv_lens: Optional[list[Optional[list[Optional[
+        list[int]]]]]] = None  # Records computed tokens for each chunk
+    next_pcp_dcp_start_rank: int = 0  # Tracks next starting rank for round-robin distribution
+    token_blank_in_last_blk: int = 0  # if the last block is not full, how many future tokens can be stored
+
     def __post_init__(self):
         self.num_prompt_tokens = length_from_prompt_token_ids_or_embeds(
             self.prompt_token_ids, self.prompt_embeds)
@@ -313,6 +319,10 @@ class InputBatch:
         self.prev_sampled_token_ids_invalid_indices: Optional[set[int]] = None
         self.prev_req_id_to_index: Optional[dict[str, int]] = None
 
+        # pcp/dcp parameters
+        self.local_chunked_kv_lens: list[Optional[list[Optional[list[Optional[
+            list[int]]]]]]] = [None] * max_num_reqs
+
     @property
     def req_ids(self) -> list[str]:
         # None elements should only be present transiently
@@ -385,6 +395,9 @@ class InputBatch:
         self.num_computed_tokens_cpu[req_index] = request.num_computed_tokens
         self.block_table.add_row(request.block_ids, req_index)
 
+        # Add PCP/DCP tracking fields
+        self.local_chunked_kv_lens[req_index] = request.local_chunked_kv_lens
+
         if sampling_params := request.sampling_params:
             if (self.is_spec_decode
                     and is_spec_decode_unsupported(sampling_params)):
@@ -680,6 +693,8 @@ class InputBatch:
                 last_req_index]
             self.num_computed_tokens_cpu[
                 empty_index] = self.num_computed_tokens_cpu[last_req_index]
+            self.local_chunked_kv_lens[
+                empty_index] = self.local_chunked_kv_lens[last_req_index]
             self.block_table.move_row(last_req_index, empty_index)
             self.temperature_cpu[empty_index] = self.temperature_cpu[
                 last_req_index]