[Core]: Option To Use Prompt Token Ids Inside Logits Processor (#4985)

Co-authored-by: Elisei Smirnov <el.smirnov@innopolis.university>

vllm/model_executor/layers/logits_processor.py

 """A layer that compute logits from hidden_stats."""
+import inspect
 from typing import Optional
 
 import torch
@@ -95,15 +96,25 @@ def _apply_logits_processors(
         seq_ids = seq_group.seq_ids
         sampling_params = seq_group.sampling_params
         logits_processors = sampling_params.logits_processors
-
         if logits_processors:
             found_logits_processors = True
+
             for seq_id, logits_row_idx in zip(seq_ids,
                                               seq_group.sample_indices):
                 logits_row = logits[logits_row_idx]
-                token_ids = seq_group.seq_data[seq_id].output_token_ids
+                past_tokens_ids = seq_group.seq_data[seq_id].output_token_ids
+                prompt_tokens_ids = seq_group.seq_data[seq_id].prompt_token_ids
+
                 for logits_processor in logits_processors:
-                    logits_row = logits_processor(token_ids, logits_row)
+                    parameters = inspect.signature(logits_processor).parameters
+                    if len(parameters) == 3:
+                        logits_row = logits_processor(prompt_tokens_ids,
+                                                      past_tokens_ids,
+                                                      logits_row)
+                    else:
+                        logits_row = logits_processor(past_tokens_ids,
+                                                      logits_row)
+
                 logits[logits_row_idx] = logits_row
 
         logits_processed += len(seq_group.sample_indices) + len(

vllm/sampling_params.py

@@ -18,10 +18,14 @@ class SamplingType(IntEnum):
     BEAM = 3
 
 
-LogitsProcessor = Callable[[List[int], torch.Tensor], torch.Tensor]
-"""LogitsProcessor is a function that takes a list of previously generated
-tokens and a tensor of the logits for the next token, and returns a modified
-tensor of logits to sample from."""
+LogitsProcessor = Union[Callable[[List[int], torch.Tensor], torch.Tensor],
+                        Callable[[List[int], List[int], torch.Tensor],
+                                 torch.Tensor]]
+"""LogitsProcessor is a function that takes a list
+of previously generated tokens, the logits tensor
+for the next token and, optionally, prompt tokens as a
+first argument, and returns a modified tensor of logits
+to sample from."""
 
 
 class SamplingParams:
@@ -95,7 +99,8 @@ class SamplingParams:
         spaces_between_special_tokens: Whether to add spaces between special
             tokens in the output.  Defaults to True.
         logits_processors: List of functions that modify logits based on
-            previously generated tokens.
+            previously generated tokens, and optionally prompt tokens as
+            a first argument.
         truncate_prompt_tokens: If set to an integer k, will use only the last k
             tokens from the prompt (i.e., left truncation). Defaults to None
             (i.e., no truncation).