[V1][Misc] Shorten `FinishReason` enum and use constant strings (#12760)

vllm/v1/engine/__init__.py

@@ -14,11 +14,17 @@ if TYPE_CHECKING:
     from vllm.multimodal.inputs import PlaceholderRange
     from vllm.sampling_params import SamplingParams
 
+# These are possible values of RequestOutput.finish_reason,
+# so form part of the external API.
+FINISH_REASON_STRINGS = ("stop", "length", "abort")
 
-class RequestFinishedReason(enum.IntEnum):
+
+class FinishReason(enum.IntEnum):
     """
     Reason a request finished - stop, length, or abort.
 
+    Int rather than Str for more compact serialization.
+
     stop - a stop string was emitted
     length - max_tokens was consumed, or max_model_len was reached
     abort - aborted for another reason
@@ -29,7 +35,7 @@ class RequestFinishedReason(enum.IntEnum):
     ABORT = 2
 
     def __str__(self):
-        return self.name.lower()
+        return FINISH_REASON_STRINGS[self.value]
 
 
 @dataclass
@@ -62,7 +68,7 @@ class EngineCoreOutput(
     request_id: str
     new_token_ids: List[int]
     finished: bool
-    finish_reason: Optional[RequestFinishedReason] = None
+    finish_reason: Optional[FinishReason] = None
     stop_reason: Union[int, str, None] = None
 
 

vllm/v1/engine/detokenizer.py

@@ -8,8 +8,7 @@ from vllm.logger import init_logger
 from vllm.sampling_params import RequestOutputKind
 from vllm.transformers_utils.detokenizer_utils import (
     AnyTokenizer, convert_prompt_ids_to_tokens, detokenize_incrementally)
-from vllm.v1.engine import (EngineCoreOutput, EngineCoreRequest,
-                            RequestFinishedReason)
+from vllm.v1.engine import EngineCoreOutput, EngineCoreRequest, FinishReason
 
 logger = init_logger(__name__)
 
@@ -19,7 +18,7 @@ class DetokenizerOutput:
     output_text: str
     token_ids: List[int]
     finished: bool
-    finish_reason: Optional[RequestFinishedReason] = None
+    finish_reason: Optional[FinishReason] = None
     stop_reason: Union[int, str, None] = None
 
 
@@ -148,7 +147,7 @@ class IncrementalDetokenizer:
                 stop_str, truncate_to = stop
                 if truncate_to != -1:
                     self.output_text = self.output_text[:truncate_to]
-                finish_reason = RequestFinishedReason.STOP
+                finish_reason = FinishReason.STOP
                 stop_reason = stop_str
 
         # TODO: handle stop_token_ids here too?

vllm/v1/metrics/loggers.py

@@ -9,7 +9,7 @@ import prometheus_client
 
 from vllm.config import ModelConfig
 from vllm.logger import init_logger
-from vllm.v1.engine import RequestFinishedReason
+from vllm.v1.engine import FinishReason
 from vllm.v1.metrics.stats import IterationStats, SchedulerStats
 
 logger = init_logger(__name__)
@@ -117,13 +117,13 @@ class PrometheusStatLogger(StatLoggerBase):
             documentation="Number of generation tokens processed.",
             labelnames=labelnames).labels(*labelvalues)
 
-        self.counter_request_success: Dict[RequestFinishedReason,
+        self.counter_request_success: Dict[FinishReason,
                                            prometheus_client.Counter] = {}
         counter_request_success_base = prometheus_client.Counter(
             name="vllm:request_success_total",
             documentation="Count of successfully processed requests.",
             labelnames=labelnames + ["finished_reason"])
-        for reason in RequestFinishedReason:
+        for reason in FinishReason:
             self.counter_request_success[
                 reason] = counter_request_success_base.labels(*(labelvalues +
                                                                 [str(reason)]))

vllm/v1/metrics/stats.py

@@ -6,7 +6,7 @@ from typing import TYPE_CHECKING, List
 
 if TYPE_CHECKING:
     from vllm.outputs import RequestOutput
-    from vllm.v1.engine import EngineCoreOutput, RequestFinishedReason
+    from vllm.v1.engine import EngineCoreOutput, FinishReason
 
 
 @dataclass
@@ -32,7 +32,7 @@ class RequestStateStats:
 class FinishedRequestStats:
     """Stats associated with a finished request."""
 
-    finish_reason: "RequestFinishedReason"
+    finish_reason: "FinishReason"
     num_prompt_tokens: int = 0
     num_generation_tokens: int = 0
 
@@ -74,8 +74,7 @@ class IterationStats:
         request_state_stats.num_generation_tokens += num_new_generation_tokens
         request_state_stats.last_token_time = now
 
-    def update_from_finished_request(self,
-                                     finish_reason: "RequestFinishedReason",
+    def update_from_finished_request(self, finish_reason: "FinishReason",
                                      request_output: "RequestOutput",
                                      request_state_stats: RequestStateStats):
         self.finished_requests.append(

vllm/v1/request.py

@@ -6,7 +6,7 @@ from typing import TYPE_CHECKING, List, Optional, Union
 from vllm.lora.request import LoRARequest
 from vllm.sampling_params import SamplingParams
 from vllm.sequence import RequestMetrics
-from vllm.v1.engine import EngineCoreRequest, RequestFinishedReason
+from vllm.v1.engine import EngineCoreRequest, FinishReason
 from vllm.v1.utils import ConstantList
 
 if TYPE_CHECKING:
@@ -109,7 +109,7 @@ class Request:
     def is_finished(self) -> bool:
         return RequestStatus.is_finished(self.status)
 
-    def get_finished_reason(self) -> Union[RequestFinishedReason, None]:
+    def get_finished_reason(self) -> Union[FinishReason, None]:
         return RequestStatus.get_finished_reason(self.status)
 
     def has_encoder_inputs(self) -> bool:
@@ -150,7 +150,7 @@ class RequestStatus(enum.IntEnum):
 
     @staticmethod
     def get_finished_reason(
-            status: "RequestStatus") -> Union[RequestFinishedReason, None]:
+            status: "RequestStatus") -> Union[FinishReason, None]:
         return _FINISHED_REASON_MAP.get(status)
 
 
@@ -159,8 +159,8 @@ class RequestStatus(enum.IntEnum):
 # are longer than the model's length cap. Therefore, the stop
 # reason should also be "length" as in OpenAI API.
 _FINISHED_REASON_MAP = {
-    RequestStatus.FINISHED_STOPPED: RequestFinishedReason.STOP,
-    RequestStatus.FINISHED_LENGTH_CAPPED: RequestFinishedReason.LENGTH,
-    RequestStatus.FINISHED_ABORTED: RequestFinishedReason.ABORT,
-    RequestStatus.FINISHED_IGNORED: RequestFinishedReason.LENGTH,
+    RequestStatus.FINISHED_STOPPED: FinishReason.STOP,
+    RequestStatus.FINISHED_LENGTH_CAPPED: FinishReason.LENGTH,
+    RequestStatus.FINISHED_ABORTED: FinishReason.ABORT,
+    RequestStatus.FINISHED_IGNORED: FinishReason.LENGTH,
 }