init

vllm/engine/output_processor/interfaces.py

@@ -0,0 +1,76 @@
+from abc import ABC, abstractmethod
+from typing import Callable, List
+
+from transformers import PreTrainedTokenizer
+
+from vllm.config import SchedulerConfig
+from vllm.core.scheduler import Scheduler
+from vllm.engine.output_processor.stop_checker import StopChecker
+from vllm.sequence import Sequence, SequenceGroup, SequenceGroupOutput
+from vllm.transformers_utils.detokenizer import Detokenizer
+from vllm.utils import Counter
+
+
+class SequenceGroupOutputProcessor(ABC):
+    """Interface for logic that processes new token ids in sequence groups,
+    managing detokenization, stop checking, and freeing/forking sequences with
+    the scheduler.
+
+    This is highly coupled with the LLMEngine and should be seen as an extension
+    of it. The logic is separated to simplify the LLMEngine class and allow
+    separate implementations for single-step decoding (which supports beam
+    search sequence forking) and multi-step decoding (which does not support
+    beam search, but does support speculative decoding).
+    """
+
+    @staticmethod
+    def create_output_processor(
+        scheduler_config: SchedulerConfig,
+        detokenizer: Detokenizer,
+        scheduler: Scheduler,
+        seq_counter: Counter,
+        get_tokenizer_for_seq: Callable[[Sequence], PreTrainedTokenizer],
+        stop_checker: "StopChecker",
+    ):
+        """Create an output processor.
+
+        This returns a single-step output processor if num_lookahead_slots is
+        zero, else returns a multi-step output processor.
+        """
+        if scheduler_config.num_lookahead_slots == 0:
+            # Importing here to avoid cycle.
+            from vllm.engine.output_processor.single_step import (
+                SingleStepOutputProcessor)
+            return SingleStepOutputProcessor(
+                scheduler_config,
+                detokenizer,
+                scheduler,
+                seq_counter,
+                stop_checker,
+            )
+        else:
+            # Importing here to avoid cycle.
+            from vllm.engine.output_processor.multi_step import (
+                MultiStepOutputProcessor)
+            return MultiStepOutputProcessor(
+                detokenizer,
+                scheduler,
+                seq_counter,
+                get_tokenizer_for_seq,
+                stop_checker,
+            )
+
+    @abstractmethod
+    def process_outputs(self, sequence_group: SequenceGroup,
+                        outputs: List[SequenceGroupOutput]) -> None:
+        """Process new token ids for the sequence group. Handles logic such as
+        detokenization, stop checking, and freeing/forking sequences in the
+        scheduler.
+        """
+        pass
+
+    @abstractmethod
+    def process_prompt_logprob(self, seq_group: SequenceGroup,
+                               outputs: List[SequenceGroupOutput]) -> None:
+        """Update prompt logprobs received from outputs to seq_group."""
+        pass