serving_chat.py 48.9 KB
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# SPDX-License-Identifier: Apache-2.0

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import asyncio
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import json
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import time
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from collections.abc import AsyncGenerator, AsyncIterator
from collections.abc import Sequence as GenericSequence
from typing import Callable, Final, Optional, Union
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import jinja2
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from fastapi import Request
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from vllm.config import ModelConfig
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from vllm.engine.protocol import EngineClient
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from vllm.entrypoints.chat_utils import (ChatTemplateContentFormatOption,
                                         ConversationMessage)
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from vllm.entrypoints.logger import RequestLogger
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from vllm.entrypoints.openai.protocol import (
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    ChatCompletionLogProb, ChatCompletionLogProbs,
    ChatCompletionLogProbsContent, ChatCompletionNamedToolChoiceParam,
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    ChatCompletionRequest, ChatCompletionResponse,
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    ChatCompletionResponseChoice, ChatCompletionResponseStreamChoice,
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    ChatCompletionStreamResponse, ChatMessage, DeltaFunctionCall, DeltaMessage,
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    DeltaToolCall, ErrorResponse, FunctionCall, PromptTokenUsageInfo,
    RequestResponseMetadata, ToolCall, UsageInfo)
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from vllm.entrypoints.openai.reasoning_parsers import (ReasoningParser,
                                                       ReasoningParserManager)
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from vllm.entrypoints.openai.serving_engine import (OpenAIServing,
                                                    clamp_prompt_logprobs)
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from vllm.entrypoints.openai.serving_models import OpenAIServingModels
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from vllm.entrypoints.openai.tool_parsers import ToolParser, ToolParserManager
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from vllm.entrypoints.openai.tool_parsers.mistral_tool_parser import (
    MistralToolCall)
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from vllm.logger import init_logger
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from vllm.outputs import CompletionOutput, RequestOutput
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from vllm.sampling_params import BeamSearchParams, SamplingParams
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from vllm.sequence import Logprob
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from vllm.transformers_utils.tokenizer import AnyTokenizer, MistralTokenizer
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from vllm.transformers_utils.tokenizers import (maybe_serialize_tool_calls,
                                                truncate_tool_call_ids)
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logger = init_logger(__name__)


class OpenAIServingChat(OpenAIServing):

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    def __init__(
        self,
        engine_client: EngineClient,
        model_config: ModelConfig,
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        models: OpenAIServingModels,
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        response_role: str,
        *,
        request_logger: Optional[RequestLogger],
        chat_template: Optional[str],
        chat_template_content_format: ChatTemplateContentFormatOption,
        return_tokens_as_token_ids: bool = False,
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        enable_reasoning: bool = False,
        reasoning_parser: Optional[str] = None,
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        enable_auto_tools: bool = False,
        tool_parser: Optional[str] = None,
        enable_prompt_tokens_details: bool = False,
    ) -> None:
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        super().__init__(engine_client=engine_client,
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                         model_config=model_config,
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                         models=models,
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                         request_logger=request_logger,
                         return_tokens_as_token_ids=return_tokens_as_token_ids)
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        self.response_role = response_role
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        self.chat_template = chat_template
        self.chat_template_content_format: Final = chat_template_content_format
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        # set up tool use
        self.enable_auto_tools: bool = enable_auto_tools
        if self.enable_auto_tools:
            logger.info(
                "\"auto\" tool choice has been enabled please note that while"
                " the parallel_tool_calls client option is preset for "
                "compatibility reasons, it will be ignored.")

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        self.enable_reasoning: bool = enable_reasoning
        self.reasoning_parser: Optional[Callable[[AnyTokenizer],
                                                 ReasoningParser]] = None
        if self.enable_reasoning:
            try:
                self.reasoning_parser = (
                    ReasoningParserManager.get_reasoning_parser(
                        reasoning_parser))
            except Exception as e:
                raise TypeError("Error: --enable-reasoning requires "
                                f"reasoning_parser:'{reasoning_parser}' "
                                "which has not been registered") from e
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        self.tool_parser: Optional[Callable[[AnyTokenizer], ToolParser]] = None
        if self.enable_auto_tools:
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            try:
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                if (tool_parser == "pythonic" and
                        model_config.model.startswith("meta-llama/Llama-3.2")):
                    logger.warning(
                        "Llama3.2 models may struggle to emit valid pythonic"
                        " tool calls")
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                self.tool_parser = ToolParserManager.get_tool_parser(
                    tool_parser)
            except Exception as e:
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                raise TypeError("Error: --enable-auto-tool-choice requires "
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                                f"tool_parser:'{tool_parser}' which has not "
                                "been registered") from e
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        self.enable_prompt_tokens_details = enable_prompt_tokens_details
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        self.default_sampling_params = (
            self.model_config.get_diff_sampling_param())
        if self.default_sampling_params:
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            source = self.model_config.generation_config
            source = "model" if source == "auto" else source
            logger.info("Using default chat sampling params from %s: %s",
                        source, self.default_sampling_params)
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    async def create_chat_completion(
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        self,
        request: ChatCompletionRequest,
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        raw_request: Optional[Request] = None,
    ) -> Union[AsyncGenerator[str, None], ChatCompletionResponse,
               ErrorResponse]:
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        """
        Chat Completion API similar to OpenAI's API.
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        See https://platform.openai.com/docs/api-reference/chat/create
        for the API specification. This API mimics the OpenAI
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        Chat Completion API.
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        """
        error_check_ret = await self._check_model(request)
        if error_check_ret is not None:
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            logger.error("Error with model %s", error_check_ret)
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            return error_check_ret

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        # If the engine is dead, raise the engine's DEAD_ERROR.
        # This is required for the streaming case, where we return a
        # success status before we actually start generating text :).
        if self.engine_client.errored:
            raise self.engine_client.dead_error

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        try:
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            (
                lora_request,
                prompt_adapter_request,
            ) = self._maybe_get_adapters(request)

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            model_name = self._get_model_name(request.model, lora_request)
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            tokenizer = await self.engine_client.get_tokenizer(lora_request)
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            tool_parser = self.tool_parser

            # validation for OpenAI tools
            # tool_choice = "required" is not supported
            if request.tool_choice == "required":
                return self.create_error_response(
                    "tool_choice = \"required\" is not supported!")

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            if isinstance(tokenizer, MistralTokenizer):
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                # because of issues with pydantic we need to potentially
                # re-serialize the tool_calls field of the request
                # for more info: see comment in `maybe_serialize_tool_calls`
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                maybe_serialize_tool_calls(request)
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                truncate_tool_call_ids(request)
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            if (request.tool_choice == "auto" and
                    not (self.enable_auto_tools and tool_parser is not None)
                    and not isinstance(tokenizer, MistralTokenizer)):
                # for hf tokenizers, "auto" tools requires
                # --enable-auto-tool-choice and --tool-call-parser
                return self.create_error_response(
                    "\"auto\" tool choice requires "
                    "--enable-auto-tool-choice and --tool-call-parser to be set"
                )
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            tool_dicts = None if request.tools is None else [
                tool.model_dump() for tool in request.tools
            ]

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            (
                conversation,
                request_prompts,
                engine_prompts,
            ) = await self._preprocess_chat(
                request,
                tokenizer,
                request.messages,
                chat_template=request.chat_template or self.chat_template,
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                chat_template_content_format=self.chat_template_content_format,
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                add_generation_prompt=request.add_generation_prompt,
                continue_final_message=request.continue_final_message,
                tool_dicts=tool_dicts,
                documents=request.documents,
                chat_template_kwargs=request.chat_template_kwargs,
                tool_parser=tool_parser,
                truncate_prompt_tokens=request.truncate_prompt_tokens,
                add_special_tokens=request.add_special_tokens,
            )
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        except (ValueError, TypeError, RuntimeError,
                jinja2.TemplateError) as e:
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            logger.exception("Error in preprocessing prompt inputs")
            return self.create_error_response(str(e))
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        request_id = "chatcmpl-" \
                     f"{self._base_request_id(raw_request, request.request_id)}"
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        request_metadata = RequestResponseMetadata(request_id=request_id)
        if raw_request:
            raw_request.state.request_metadata = request_metadata

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        # Schedule the request and get the result generator.
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        generators: list[AsyncGenerator[RequestOutput, None]] = []
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        try:
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            for i, engine_prompt in enumerate(engine_prompts):
                sampling_params: Union[SamplingParams, BeamSearchParams]
                default_max_tokens = self.max_model_len - len(
                    engine_prompt["prompt_token_ids"])
                if request.use_beam_search:
                    sampling_params = request.to_beam_search_params(
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                        default_max_tokens, self.default_sampling_params)
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                else:
                    sampling_params = request.to_sampling_params(
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                        default_max_tokens,
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                        self.model_config.logits_processor_pattern,
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                        self.default_sampling_params)
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                self._log_inputs(request_id,
                                 request_prompts[i],
                                 params=sampling_params,
                                 lora_request=lora_request,
                                 prompt_adapter_request=prompt_adapter_request)

                trace_headers = (None if raw_request is None else await
                                 self._get_trace_headers(raw_request.headers))

                if isinstance(sampling_params, BeamSearchParams):
                    generator = self.engine_client.beam_search(
                        prompt=engine_prompt,
                        request_id=request_id,
                        params=sampling_params,
                    )
                else:
                    generator = self.engine_client.generate(
                        engine_prompt,
                        sampling_params,
                        request_id,
                        lora_request=lora_request,
                        trace_headers=trace_headers,
                        prompt_adapter_request=prompt_adapter_request,
                        priority=request.priority,
                    )

                generators.append(generator)
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        except ValueError as e:
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            # TODO: Use a vllm-specific Validation Error
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            return self.create_error_response(str(e))

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        assert len(generators) == 1
        result_generator, = generators

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        # Streaming response
        if request.stream:
            return self.chat_completion_stream_generator(
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                request, result_generator, request_id, model_name,
                conversation, tokenizer, request_metadata)
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        try:
            return await self.chat_completion_full_generator(
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                request, result_generator, request_id, model_name,
                conversation, tokenizer, request_metadata)
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        except ValueError as e:
            # TODO: Use a vllm-specific Validation Error
            return self.create_error_response(str(e))
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    def get_chat_request_role(self, request: ChatCompletionRequest) -> str:
        if request.add_generation_prompt:
            return self.response_role
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        return request.messages[-1]["role"]
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    async def chat_completion_stream_generator(
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        self,
        request: ChatCompletionRequest,
        result_generator: AsyncIterator[RequestOutput],
        request_id: str,
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        model_name: str,
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        conversation: list[ConversationMessage],
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        tokenizer: AnyTokenizer,
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        request_metadata: RequestResponseMetadata,
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    ) -> AsyncGenerator[str, None]:
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        created_time = int(time.time())
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        chunk_object_type: Final = "chat.completion.chunk"
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        first_iteration = True
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        # Send response for each token for each request.n (index)
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        num_choices = 1 if request.n is None else request.n
        previous_num_tokens = [0] * num_choices
        finish_reason_sent = [False] * num_choices
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        num_prompt_tokens = 0
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        num_cached_tokens = None
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        if isinstance(request.tool_choice, ChatCompletionNamedToolChoiceParam):
            tool_choice_function_name = request.tool_choice.function.name
        else:
            tool_choice_function_name = None

        # Determine whether tools are in use with "auto" tool choice
        tool_choice_auto = (
            not tool_choice_function_name
            and self._should_stream_with_auto_tool_parsing(request))

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        should_stream_with_reasoning_parsing = (
            self._should_stream_with_reasoning_parsing(request))

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        all_previous_token_ids: Optional[list[list[int]]]
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        # Only one of these will be used, thus previous_texts and
        # all_previous_token_ids will not be used twice in the same iteration.
        if tool_choice_auto or should_stream_with_reasoning_parsing:
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            # These are only required in "auto" tool choice case
            previous_texts = [""] * num_choices
            all_previous_token_ids = [[]] * num_choices
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            # For reasoning parser and tool call all enabled
            added_content_delta_arr = [False] * num_choices
            reasoning_end_arr = [False] * num_choices
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        else:
            previous_texts, all_previous_token_ids = None, None

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        try:
            # There is no need to check if the reasoning_parser is None
            # because the should_stream_with_reasoning_parsing check
            # already ensures that the reasoning_parser is not None.
            # but the pre-commit hook requires it.
            if should_stream_with_reasoning_parsing and \
                self.reasoning_parser is not None:
                reasoning_parser = self.reasoning_parser(tokenizer)
        except RuntimeError as e:
            logger.exception("Error in reasoning parser creation.")
            data = self.create_streaming_error_response(str(e))
            yield f"data: {data}\n\n"
            yield "data: [DONE]\n\n"
            return

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        # Prepare the tool parser if it's needed
        try:
            if tool_choice_auto and self.tool_parser:
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                tool_parsers: list[Optional[ToolParser]] = [
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                    self.tool_parser(tokenizer)
                ] * num_choices
            else:
                tool_parsers = [None] * num_choices
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        except Exception as e:
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            logger.exception("Error in tool parser creation.")
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            data = self.create_streaming_error_response(str(e))
            yield f"data: {data}\n\n"
            yield "data: [DONE]\n\n"
            return

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        stream_options = request.stream_options
        if stream_options:
            include_usage = stream_options.include_usage
            include_continuous_usage = include_usage and \
                                       stream_options.continuous_usage_stats
        else:
            include_usage, include_continuous_usage = False, False

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        try:
            async for res in result_generator:
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                if res.prompt_token_ids is not None:
                    num_prompt_tokens = len(res.prompt_token_ids)
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                    if res.encoder_prompt_token_ids is not None:
                        num_prompt_tokens += len(res.encoder_prompt_token_ids)
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                # We need to do it here, because if there are exceptions in
                # the result_generator, it needs to be sent as the FIRST
                # response (by the try...catch).
                if first_iteration:
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                    num_cached_tokens = res.num_cached_tokens
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                    # Send first response for each request.n (index) with
                    # the role
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                    role = self.get_chat_request_role(request)
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                    # NOTE num_choices defaults to 1 so this usually executes
                    # once per request
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                    for i in range(num_choices):
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                        choice_data = ChatCompletionResponseStreamChoice(
                            index=i,
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                            delta=DeltaMessage(
                                role=role,
                                content="",
                            ),
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                            logprobs=None,
                            finish_reason=None)
                        chunk = ChatCompletionStreamResponse(
                            id=request_id,
                            object=chunk_object_type,
                            created=created_time,
                            choices=[choice_data],
                            model=model_name)
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                        # if continuous usage stats are requested, add it
                        if include_continuous_usage:
                            chunk.usage = UsageInfo(
                                prompt_tokens=num_prompt_tokens,
                                completion_tokens=0,
                                total_tokens=num_prompt_tokens)
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                        data = chunk.model_dump_json(exclude_unset=True)
                        yield f"data: {data}\n\n"

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                    # Send response to echo the input portion of the
                    # last message
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                    if request.echo:
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                        last_msg_content: Union[str, list[dict[str, str]]] = ""
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                        if conversation and "content" in conversation[
                                -1] and conversation[-1].get("role") == role:
                            last_msg_content = conversation[-1]["content"] or ""
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                        if last_msg_content:
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                            for i in range(num_choices):
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                                choice_data = (
                                    ChatCompletionResponseStreamChoice(
                                        index=i,
                                        delta=DeltaMessage(
                                            content=last_msg_content),
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                                        logprobs=None,
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                                        finish_reason=None))
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                                chunk = ChatCompletionStreamResponse(
                                    id=request_id,
                                    object=chunk_object_type,
                                    created=created_time,
                                    choices=[choice_data],
                                    model=model_name)
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                                if include_continuous_usage:
                                    chunk.usage = UsageInfo(
                                        prompt_tokens=num_prompt_tokens,
                                        completion_tokens=0,
                                        total_tokens=num_prompt_tokens)
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                                data = chunk.model_dump_json(
                                    exclude_unset=True)
                                yield f"data: {data}\n\n"
                    first_iteration = False

                for output in res.outputs:
                    i = output.index
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                    tool_parser = tool_parsers[i]
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                    if finish_reason_sent[i]:
                        continue

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                    if request.logprobs and request.top_logprobs is not None:
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                        assert output.logprobs is not None, (
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                            "Did not output logprobs")
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                        logprobs = self._create_chat_logprobs(
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                            token_ids=output.token_ids,
                            top_logprobs=output.logprobs,
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                            tokenizer=tokenizer,
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                            num_output_top_logprobs=request.top_logprobs,
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                            return_as_token_id=request.
                            return_tokens_as_token_ids,
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                        )
                    else:
                        logprobs = None

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                    delta_text = output.text
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                    if not delta_text and not output.token_ids and \
                        not previous_num_tokens[i]:
                        # Chunked prefill case, don't return empty chunks
                        continue

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                    delta_message: Optional[DeltaMessage]
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                    # just update previous_texts and previous_token_ids
                    if tool_choice_auto or should_stream_with_reasoning_parsing:
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                        assert previous_texts is not None
                        assert all_previous_token_ids is not None
                        previous_text = previous_texts[i]
                        previous_token_ids = all_previous_token_ids[i]
                        current_text = previous_text + delta_text
                        current_token_ids = previous_token_ids + list(
                            output.token_ids)

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                    # handle streaming deltas for tools with named tool_choice
                    if tool_choice_function_name:
                        if (self.enable_reasoning
                                and not reasoning_parser.is_reasoning_end(
                                    previous_token_ids)):
                            assert reasoning_parser is not None
                            delta_message = (
                                reasoning_parser.
                                extract_reasoning_content_streaming(
                                    previous_text,
                                    current_text,
                                    delta_text,
                                    previous_token_ids,
                                    current_token_ids,
                                    output.token_ids,
                                ))
                            # When encountering think end id in delta_token_ids,
                            # process the `content`. Only keep 'content',
                            # remove 'reasoning_content'
                            if reasoning_parser.is_reasoning_end(
                                    list(output.token_ids)):
                                if delta_message and delta_message.content:
                                    # This need to be added to next `delta_text`
                                    current_text = delta_message.content
                                    delta_message.content = None
                                else:
                                    current_text = ""
                        else:
                            # Just to add remaining `content`
                            if self.enable_reasoning:
                                delta_text = previous_text + delta_text
                                current_text = ""

                            delta_message = DeltaMessage(tool_calls=[
                                DeltaToolCall(function=DeltaFunctionCall(
                                    name=tool_choice_function_name,
                                    arguments=delta_text),
                                              index=i)
                            ])

                    # handle streaming deltas for tools with "auto" tool choice
                    # and reasoning parser
                    elif tool_choice_auto and self.enable_reasoning:
                        assert tool_parser is not None
                        assert reasoning_parser is not None
                        assert added_content_delta_arr is not None
                        assert reasoning_end_arr is not None
                        if not reasoning_end_arr[i]:
                            delta_message = (
                                reasoning_parser.
                                extract_reasoning_content_streaming(
                                    previous_text,
                                    current_text,
                                    delta_text,
                                    previous_token_ids,
                                    current_token_ids,
                                    output.token_ids,
                                ))

                            # When encountering think end id in delta_token_ids,
                            # set reasoning status to end.
                            # Remove the text and token ids related
                            # to 'reasoning_content'.
                            if reasoning_parser.is_reasoning_end(
                                    list(output.token_ids)):
                                reasoning_end_arr[i] = True
                                current_token_ids =  \
                                    reasoning_parser.extract_content_ids(
                                        list(output.token_ids))
                                if delta_message and delta_message.content:
                                    current_text = delta_message.content
                                    delta_message.content = None
                                else:
                                    current_text = ""

                        # handle tool calls only after reasoning is done,
                        else:
                            delta_token_ids = list(output.token_ids)
                            # First time to tool call,
                            # add the remaining text and token ids
                            # to delta from previous
                            if not added_content_delta_arr[i]:
                                added_content_delta_arr[i] = True
                                previous_text = ""
                                previous_token_ids = []
                                delta_text = current_text
                                delta_token_ids = current_token_ids

                            delta_message = (
                                tool_parser.extract_tool_calls_streaming(
                                    previous_text=previous_text,
                                    current_text=current_text,
                                    delta_text=delta_text,
                                    previous_token_ids=previous_token_ids,
                                    current_token_ids=current_token_ids,
                                    delta_token_ids=delta_token_ids,
                                    request=request))
                    # when only tool calls
                    elif tool_choice_auto:
                        assert tool_parser is not None
585
586
                        delta_message = (
                            tool_parser.extract_tool_calls_streaming(
587
588
                                previous_text=previous_text,
                                current_text=current_text,
589
                                delta_text=delta_text,
590
591
                                previous_token_ids=previous_token_ids,
                                current_token_ids=current_token_ids,
592
593
                                delta_token_ids=output.token_ids,
                                request=request))
594
                    # when only reasoning
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604
605
                    elif self.enable_reasoning:
                        assert reasoning_parser is not None
                        delta_message = (reasoning_parser.
                                         extract_reasoning_content_streaming(
                                             previous_text,
                                             current_text,
                                             delta_text,
                                             previous_token_ids,
                                             current_token_ids,
                                             output.token_ids,
                                         ))
606
                    # handle streaming just a content delta
607
608
609
                    else:
                        delta_message = DeltaMessage(content=delta_text)

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612
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615
616
                    # update the previous values for the next iteration
                    if tool_choice_auto or should_stream_with_reasoning_parsing:
                        assert previous_texts is not None
                        assert all_previous_token_ids is not None
                        previous_texts[i] = current_text
                        all_previous_token_ids[i] = current_token_ids

617
                    # set the previous values for the next iteration
618
                    previous_num_tokens[i] += len(output.token_ids)
619
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621
622
623
624
625
626

                    # if the message delta is None (e.g. because it was a
                    # "control token" for tool calls or the parser otherwise
                    # wasn't ready to send a token, then
                    #   get the next token without streaming a chunk
                    if delta_message is None:
                        continue

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629
630
                    if output.finish_reason is None:
                        # Send token-by-token response for each request.n
                        choice_data = ChatCompletionResponseStreamChoice(
                            index=i,
631
                            delta=delta_message,
632
633
                            logprobs=logprobs,
                            finish_reason=None)
634
635

                    # if the model is finished generating
636
                    else:
637
638
639
640
                        # check to make sure we haven't "forgotten" to stream
                        #   any tokens that were generated but previously
                        #   matched by partial json parsing
                        # only happens if we are NOT using guided decoding
641
                        auto_tools_called = False
642
                        if tool_parser:
643
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645
646
                            auto_tools_called = len(
                                tool_parser.prev_tool_call_arr) > 0
                            index = len(tool_parser.prev_tool_call_arr
                                        ) - 1 if auto_tools_called else 0
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649
650
651
                        else:
                            index = 0

                        if self._should_check_for_unstreamed_tool_arg_tokens(
                                delta_message, output) and tool_parser:
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656
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660
661
                            latest_delta_len = 0
                            if ((isinstance(
                                    delta_message.tool_calls[0].function,
                                    DeltaFunctionCall)) and isinstance(
                                        delta_message.tool_calls[0].function.
                                        arguments, str)):
                                latest_delta_len = len(
                                    delta_message.tool_calls[0].function.
                                    arguments)

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664
665
                            # get the expected call based on partial JSON
                            # parsing which "autocompletes" the JSON
                            expected_call = json.dumps(
                                tool_parser.prev_tool_call_arr[index].get(
666
667
                                    "arguments", {}),
                                ensure_ascii=False)
668

669
                            # get what we've streamed so far for arguments
670
671
672
                            # for the current tool
                            actual_call = tool_parser.streamed_args_for_tool[
                                index]
673
674
                            if (latest_delta_len > 0):
                                actual_call = actual_call[:-latest_delta_len]
675
676
677
678
679
680
681
682
683
684
685
686

                            # check to see if there's anything left to stream
                            remaining_call = expected_call.replace(
                                actual_call, "", 1)
                            # set that as a delta message
                            delta_message = DeltaMessage(tool_calls=[
                                DeltaToolCall(index=index,
                                              function=DeltaFunctionCall(
                                                  arguments=remaining_call).
                                              model_dump(exclude_none=True))
                            ])

687
688
689
                        # Send the finish response for each request.n only once
                        choice_data = ChatCompletionResponseStreamChoice(
                            index=i,
690
                            delta=delta_message,
691
                            logprobs=logprobs,
692
                            finish_reason=output.finish_reason
693
                            if not auto_tools_called else "tool_calls",
694
                            stop_reason=output.stop_reason)
695

696
                        finish_reason_sent[i] = True
697

698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
                    chunk = ChatCompletionStreamResponse(
                        id=request_id,
                        object=chunk_object_type,
                        created=created_time,
                        choices=[choice_data],
                        model=model_name)

                    # handle usage stats if requested & if continuous
                    if include_continuous_usage:
                        completion_tokens = previous_num_tokens[i]
                        chunk.usage = UsageInfo(
                            prompt_tokens=num_prompt_tokens,
                            completion_tokens=completion_tokens,
                            total_tokens=num_prompt_tokens + completion_tokens,
                        )

                    data = chunk.model_dump_json(exclude_unset=True)
                    yield f"data: {data}\n\n"

717
718
            # once the final token is handled, if stream_options.include_usage
            # is sent, send the usage
719
720
            if include_usage:
                completion_tokens = sum(previous_num_tokens)
721
722
723
724
725
726
727
                final_usage = UsageInfo(prompt_tokens=num_prompt_tokens,
                                        completion_tokens=completion_tokens,
                                        total_tokens=num_prompt_tokens +
                                        completion_tokens)
                if self.enable_prompt_tokens_details and num_cached_tokens:
                    final_usage.prompt_tokens_details = PromptTokenUsageInfo(
                        cached_tokens=num_cached_tokens)
728
729
730
731
732
733
734
735
736
737
738

                final_usage_chunk = ChatCompletionStreamResponse(
                    id=request_id,
                    object=chunk_object_type,
                    created=created_time,
                    choices=[],
                    model=model_name,
                    usage=final_usage)
                final_usage_data = (final_usage_chunk.model_dump_json(
                    exclude_unset=True, exclude_none=True))
                yield f"data: {final_usage_data}\n\n"
739

740
741
742
743
744
745
746
            # report to FastAPI middleware aggregate usage across all choices
            num_completion_tokens = sum(previous_num_tokens)
            request_metadata.final_usage_info = UsageInfo(
                prompt_tokens=num_prompt_tokens,
                completion_tokens=num_completion_tokens,
                total_tokens=num_prompt_tokens + num_completion_tokens)

747
        except Exception as e:
748
            # TODO: Use a vllm-specific Validation Error
749
            logger.exception("Error in chat completion stream generator.")
750
751
            data = self.create_streaming_error_response(str(e))
            yield f"data: {data}\n\n"
752
753
754
755
        # Send the final done message after all response.n are finished
        yield "data: [DONE]\n\n"

    async def chat_completion_full_generator(
756
757
758
759
        self,
        request: ChatCompletionRequest,
        result_generator: AsyncIterator[RequestOutput],
        request_id: str,
760
        model_name: str,
761
        conversation: list[ConversationMessage],
762
        tokenizer: AnyTokenizer,
763
        request_metadata: RequestResponseMetadata,
764
    ) -> Union[ErrorResponse, ChatCompletionResponse]:
765

766
        created_time = int(time.time())
767
        final_res: Optional[RequestOutput] = None
768

769
770
771
772
773
        try:
            async for res in result_generator:
                final_res = res
        except asyncio.CancelledError:
            return self.create_error_response("Client disconnected")
774
775
776
        except ValueError as e:
            # TODO: Use a vllm-specific Validation Error
            return self.create_error_response(str(e))
777

778
779
        assert final_res is not None

780
        choices: list[ChatCompletionResponseChoice] = []
781

782
783
        role = self.get_chat_request_role(request)
        for output in final_res.outputs:
784
            token_ids = output.token_ids
785
            out_logprobs = output.logprobs
786

787
788
            if request.logprobs and request.top_logprobs is not None:
                assert out_logprobs is not None, "Did not output logprobs"
789
                logprobs = self._create_chat_logprobs(
790
                    token_ids=token_ids,
791
                    top_logprobs=out_logprobs,
792
                    num_output_top_logprobs=request.top_logprobs,
793
                    tokenizer=tokenizer,
794
                    return_as_token_id=request.return_tokens_as_token_ids,
795
796
797
798
                )
            else:
                logprobs = None

799
800
801
            should_stream_with_reasoning_parsing = (
                self._should_stream_with_reasoning_parsing(request))

802
803
804
805
            # In the OpenAI API the finish_reason is "tools_called"
            # if the tool choice is auto and the model produced a tool
            # call. The same is not true for named function calls
            auto_tools_called = False
806

807
808
809
810
811
812
813
            if should_stream_with_reasoning_parsing and \
                self.reasoning_parser is not None:
                try:
                    reasoning_parser = self.reasoning_parser(tokenizer)
                except RuntimeError as e:
                    logger.exception("Error in reasoning parser creation.")
                    return self.create_error_response(str(e))
814
815
                # If the reasoning parser is enabled,
                # tool calls are extracted exclusively from the content.
816
817
818
                reasoning_content, content = (
                    reasoning_parser.extract_reasoning_content(
                        output.text, request=request))
819
820
821
            else:
                reasoning_content = None
                content = output.text
822

823
824
            # if auto tools are not enabled, and a named tool choice using
            #   outlines is not being used
825
826
827
828
829
830
831
            if (not self.enable_auto_tools
                    or not self.tool_parser) and not isinstance(
                        request.tool_choice,
                        ChatCompletionNamedToolChoiceParam):
                message = ChatMessage(role=role,
                                      reasoning_content=reasoning_content,
                                      content=content)
832
833
834

            # if the request uses tools and specified a tool choice
            elif request.tool_choice and type(
835
                    request.tool_choice) is ChatCompletionNamedToolChoiceParam:
836

837
838
                tool_call_class = MistralToolCall if isinstance(
                    tokenizer, MistralTokenizer) else ToolCall
839
840
                message = ChatMessage(
                    role=role,
841
                    reasoning_content=reasoning_content,
842
843
                    content="",
                    tool_calls=[
844
                        tool_call_class(function=FunctionCall(
845
                            name=request.tool_choice.function.name,
846
                            arguments=content))
847
                    ])
848
849
850

            # if the request doesn't use tool choice
            # OR specifies to not use a tool
851
            elif not request.tool_choice or request.tool_choice == "none":
852

853
854
855
                message = ChatMessage(role=role,
                                      reasoning_content=reasoning_content,
                                      content=content)
856
857
858
859
860
861
862

            # handle when there are tools and tool choice is auto
            elif request.tools and (
                    request.tool_choice == "auto"
                    or request.tool_choice is None) and self.enable_auto_tools \
                    and self.tool_parser:

863
864
865
                try:
                    tool_parser = self.tool_parser(tokenizer)
                except RuntimeError as e:
866
                    logger.exception("Error in tool parser creation.")
867
868
                    return self.create_error_response(str(e))

869
                tool_call_info = tool_parser.extract_tool_calls(
870
                    content if content is not None else "", request=request)
871
872
873
874
                # In the OpenAI API the finish_reason is "tools_called"
                # if the tool choice is auto and the model produced a tool
                # call. The same is not true for named function calls
                auto_tools_called = tool_call_info.tools_called
875
876
                if tool_call_info.tools_called:
                    message = ChatMessage(role=role,
877
                                          reasoning_content=reasoning_content,
878
879
880
881
882
883
                                          content=tool_call_info.content,
                                          tool_calls=tool_call_info.tool_calls)

                else:
                    # FOR NOW make it a chat message; we will have to detect
                    # the type to make it later.
884
885
886
                    message = ChatMessage(role=role,
                                          reasoning_content=reasoning_content,
                                          content=content)
887
888
889
890
891
892
893

            # undetermined case that is still important to handle
            else:
                logger.error(
                    "Error in chat_completion_full_generator - cannot determine"
                    " if tools should be extracted. Returning a standard chat "
                    "completion.")
894
895
896
                message = ChatMessage(role=role,
                                      reasoning_content=reasoning_content,
                                      content=content)
897

898
899
            choice_data = ChatCompletionResponseChoice(
                index=output.index,
900
                message=message,
901
                logprobs=logprobs,
902
                finish_reason="tool_calls" if auto_tools_called else
903
                output.finish_reason if output.finish_reason else "stop",
904
                stop_reason=output.stop_reason)
905
906
            choices.append(choice_data)

907
        if request.echo:
908
            last_msg_content: Union[str, list[dict[str, str]]] = ""
909
910
            if conversation and "content" in conversation[-1] and conversation[
                    -1].get("role") == role:
911
                last_msg_content = conversation[-1]["content"] or ""
912
913
914
            if isinstance(last_msg_content, list):
                last_msg_content = "\n".join(msg['text']
                                             for msg in last_msg_content)
915
916

            for choice in choices:
917
918
                full_message = last_msg_content + (choice.message.content
                                                   or "")
919
920
                choice.message.content = full_message

921
        assert final_res.prompt_token_ids is not None
922
        num_prompt_tokens = len(final_res.prompt_token_ids)
923
924
        if final_res.encoder_prompt_token_ids is not None:
            num_prompt_tokens += len(final_res.encoder_prompt_token_ids)
925
926
        num_generated_tokens = sum(
            len(output.token_ids) for output in final_res.outputs)
927
928
929
930
931
932
933
        usage = UsageInfo(prompt_tokens=num_prompt_tokens,
                          completion_tokens=num_generated_tokens,
                          total_tokens=num_prompt_tokens +
                          num_generated_tokens)
        if self.enable_prompt_tokens_details and final_res.num_cached_tokens:
            usage.prompt_tokens_details = PromptTokenUsageInfo(
                cached_tokens=final_res.num_cached_tokens)
934
935
936

        request_metadata.final_usage_info = usage

937
938
939
940
941
942
        response = ChatCompletionResponse(
            id=request_id,
            created=created_time,
            model=model_name,
            choices=choices,
            usage=usage,
943
            prompt_logprobs=clamp_prompt_logprobs(final_res.prompt_logprobs),
944
945
        )

946
        return response
947
948

    def _get_top_logprobs(
949
            self, logprobs: dict[int, Logprob], top_logprobs: Optional[int],
950
951
            tokenizer: AnyTokenizer,
            should_return_as_token_id: bool) -> list[ChatCompletionLogProb]:
952
        return [
953
954
955
956
            ChatCompletionLogProb(token=(token := self._get_decoded_token(
                p[1],
                p[0],
                tokenizer,
957
                return_as_token_id=should_return_as_token_id)),
958
959
960
                                  logprob=max(p[1].logprob, -9999.0),
                                  bytes=list(
                                      token.encode("utf-8", errors="replace")))
961
962
963
964
965
966
967
            for i, p in enumerate(logprobs.items())
            if top_logprobs and i < top_logprobs
        ]

    def _create_chat_logprobs(
        self,
        token_ids: GenericSequence[int],
968
        top_logprobs: GenericSequence[Optional[dict[int, Logprob]]],
969
        tokenizer: AnyTokenizer,
970
        num_output_top_logprobs: Optional[int] = None,
971
        return_as_token_id: Optional[bool] = None,
972
973
    ) -> ChatCompletionLogProbs:
        """Create OpenAI-style logprobs."""
974
        logprobs_content: list[ChatCompletionLogProbsContent] = []
975

976
977
        should_return_as_token_id = return_as_token_id if \
            return_as_token_id is not None else self.return_tokens_as_token_ids
978
979
980
        for i, token_id in enumerate(token_ids):
            step_top_logprobs = top_logprobs[i]
            if step_top_logprobs is None:
981
                token = tokenizer.decode(token_id)
982
                if should_return_as_token_id:
983
                    token = f"token_id:{token_id}"
984

985
986
                logprobs_content.append(
                    ChatCompletionLogProbsContent(
987
                        token=token,
988
989
                        bytes=list(token.encode("utf-8", errors="replace")),
                    ))
990
            else:
991
992
993
                step_token = step_top_logprobs[token_id]
                step_decoded = step_token.decoded_token

994
995
                logprobs_content.append(
                    ChatCompletionLogProbsContent(
996
                        token=self._get_decoded_token(
997
998
999
                            step_token,
                            token_id,
                            tokenizer,
1000
                            should_return_as_token_id,
1001
1002
1003
1004
                        ),
                        logprob=max(step_token.logprob, -9999.0),
                        bytes=None if step_decoded is None else list(
                            step_decoded.encode("utf-8", errors="replace")),
1005
                        top_logprobs=self._get_top_logprobs(
1006
1007
                            step_top_logprobs, num_output_top_logprobs,
                            tokenizer, should_return_as_token_id),
1008
                    ))
1009
1010

        return ChatCompletionLogProbs(content=logprobs_content)
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024

    def _should_stream_with_auto_tool_parsing(self,
                                              request: ChatCompletionRequest):
        """
        Utility function to check if streamed tokens should go through the tool
        call parser that was configured.

        We only want to do this IF user-provided tools are set, a tool parser
        is configured, "auto" tool choice is enabled, and the request's tool
        choice field indicates that "auto" tool choice should be used.
        """
        return (request.tools and self.tool_parser and self.enable_auto_tools
                and request.tool_choice in ['auto', None])

1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
    def _should_stream_with_reasoning_parsing(self,
                                              request: ChatCompletionRequest):
        """
            Utility function to check if streamed tokens should go through the
            reasoning parser that was configured.
    
            We only want to do this IF reasoning is enabled and a reasoning 
            parser is configured.
            """
        return self.enable_reasoning and self.reasoning_parser is not None

1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
    def _should_check_for_unstreamed_tool_arg_tokens(
        self,
        delta_message: Optional[DeltaMessage],
        output: CompletionOutput,
    ) -> bool:
        """
        Check to see if we should check for unstreamed tool arguments tokens.
        This is only applicable when auto tool parsing is enabled, the delta
        is a tool call with arguments.
        """

        # yapf: disable
        return bool(
            # if there is a delta message that includes tool calls which
            # include a function that has arguments
1051
1052
            output.finish_reason is not None
            and self.enable_auto_tools and self.tool_parser and delta_message
1053
1054
1055
1056
            and delta_message.tool_calls and delta_message.tool_calls[0]
            and delta_message.tool_calls[0].function
            and delta_message.tool_calls[0].function.arguments is not None
        )