478 lines
22 KiB
Python
478 lines
22 KiB
Python
# SPDX-License-Identifier: Apache-2.0
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# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
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import itertools
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import multiprocessing
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from collections.abc import Iterable, Sequence
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from concurrent.futures import Future, ThreadPoolExecutor
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from typing import TYPE_CHECKING
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from vllm.config import VllmConfig
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from vllm.logger import init_logger
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from vllm.reasoning import ReasoningParserManager
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from vllm.tokenizers import cached_tokenizer_from_config
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from vllm.utils.import_utils import LazyLoader
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from vllm.v1.structured_output.backend_guidance import GuidanceBackend
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from vllm.v1.structured_output.backend_types import (
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StructuredOutputBackend,
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StructuredOutputGrammar,
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StructuredOutputOptions,
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)
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from vllm.v1.structured_output.backend_xgrammar import XgrammarBackend
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if TYPE_CHECKING:
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import numpy as np
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import numpy.typing as npt
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import torch
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from vllm.reasoning import ReasoningParser
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from vllm.v1.request import Request
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else:
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torch = LazyLoader("torch", globals(), "torch")
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logger = init_logger(__name__)
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class StructuredOutputManager:
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"""Engine-level manager for structured output requests."""
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def __init__(self, vllm_config: VllmConfig):
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self.backend: StructuredOutputBackend | None = None
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# We only store the class of the reasoner in the manager.
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# The parser instance is request-scoped because some reasoning parsers
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# depend on per-request chat-template kwargs.
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self.reasoner_cls: type[ReasoningParser] | None = None
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self.vllm_config = vllm_config
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# When in external_launcher mode, async grammar compilation causes deadlocks
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# due to external_launcher mode having a scheduler for each TP rank.
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# Async grammar compilation causes the
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# WAITING_FOR_STRUCTURED_OUTPUT_GRAMMAR → WAITING transition to
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# happen at different times on different TP ranks,
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# breaking the determinism assumption that external_launcher relies on.
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self._use_async_grammar_compilation = (
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vllm_config.parallel_config.distributed_executor_backend
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!= "external_launcher"
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)
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self._grammar_bitmask: torch.Tensor | None = None
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self._full_mask = torch.tensor(-1, dtype=torch.int32)
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max_batch_size = self.vllm_config.scheduler_config.max_num_seqs
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self.fill_bitmask_parallel_threshold = 128
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if self.fill_bitmask_parallel_threshold < max_batch_size:
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self.fill_bitmask_parallel_batch_size = 16
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# Use:
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# - at least 1 CPU
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# - at most half the number of CPUs or 8, whichever is less
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max_workers = max(1, min(multiprocessing.cpu_count() // 2, 8))
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self.executor_for_fillmask = ThreadPoolExecutor(max_workers=max_workers)
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if not self.vllm_config.model_config.skip_tokenizer_init:
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# The default max_workers if not specified is the number of
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# CPUs * 5, which is way too high since these tasks are CPU-bound,
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# not I/O bound. We also know we would never dominate CPU usage
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# with just grammar compilation, so we set it to half the number
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# of CPUs.
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max_workers = max(1, (multiprocessing.cpu_count() + 1) // 2)
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self.executor = ThreadPoolExecutor(max_workers=max_workers)
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self.tokenizer = cached_tokenizer_from_config(
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model_config=self.vllm_config.model_config
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)
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reasoning_parser_plugin = (
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self.vllm_config.structured_outputs_config.reasoning_parser_plugin
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)
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if reasoning_parser_plugin and len(reasoning_parser_plugin) > 3:
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ReasoningParserManager.import_reasoning_parser(reasoning_parser_plugin)
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reasoning_parser = (
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self.vllm_config.structured_outputs_config.reasoning_parser
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)
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if reasoning_parser:
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self.reasoner_cls = ReasoningParserManager.get_reasoning_parser(
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reasoning_parser
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)
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self.enable_in_reasoning = (
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self.vllm_config.structured_outputs_config.enable_in_reasoning
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)
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def _get_reasoner(self, request: "Request") -> "ReasoningParser | None":
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structured_req = request.structured_output_request
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if structured_req is None or self.reasoner_cls is None:
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return None
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if structured_req.reasoner is None:
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# Lazily build the request-local parser so the structured-output
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# gate observes the same template kwargs used by the frontend.
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parser_kwargs = structured_req.reasoning_parser_kwargs or {}
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structured_req.reasoner = self.reasoner_cls(
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tokenizer=self.tokenizer,
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**parser_kwargs,
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)
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return structured_req.reasoner
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def grammar_init(self, request: "Request") -> None:
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if request.structured_output_request is None:
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return
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if TYPE_CHECKING:
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assert (
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request.sampling_params is not None
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and request.sampling_params.structured_outputs is not None
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)
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# Initialize the backend the first time it is needed.
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#
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# NOTE: We only support a single backend. We do NOT support different
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# backends on a per-request basis in V1 (for now, anyway...).
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# _backend is set in Processor._validate_structured_output
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if self.backend is None:
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assert request.sampling_params is not None
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backend = request.sampling_params.structured_outputs._backend
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vocab_size = self.vllm_config.model_config.get_vocab_size()
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if backend == "xgrammar":
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self.backend = XgrammarBackend(
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self.vllm_config,
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tokenizer=self.tokenizer,
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vocab_size=vocab_size,
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)
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elif backend == "guidance":
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self.backend = GuidanceBackend(
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self.vllm_config,
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tokenizer=self.tokenizer,
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vocab_size=vocab_size,
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)
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elif backend == "outlines":
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from vllm.v1.structured_output.backend_outlines import OutlinesBackend
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self.backend = OutlinesBackend(
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self.vllm_config,
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tokenizer=self.tokenizer,
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vocab_size=vocab_size,
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)
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elif backend == "lm-format-enforcer":
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from vllm.v1.structured_output.backend_lm_format_enforcer import ( # noqa: E501
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LMFormatEnforcerBackend,
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)
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self.backend = LMFormatEnforcerBackend(
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self.vllm_config,
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tokenizer=self.tokenizer,
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vocab_size=vocab_size,
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)
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else:
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raise ValueError(f"Unsupported structured output backend: {backend}")
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if self._use_async_grammar_compilation:
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grammar = self.executor.submit(self._create_grammar, request)
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else:
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grammar = self._create_grammar(request) # type: ignore[assignment]
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request.structured_output_request.grammar = grammar # type: ignore[assignment]
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def _create_grammar(self, request: "Request") -> StructuredOutputGrammar:
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key = request.structured_output_request.structured_output_key # type: ignore[union-attr]
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# Note that the request was validated in the engine core client,
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# so at this point we know it is a supported type of request.
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#
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# TODO: we still need to handle xgrammar compilation failures,
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# though it should be unlikely as we test that up front as well.
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request_type, grammar_spec = key
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assert self.backend is not None
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return self.backend.compile_grammar(request_type, grammar_spec)
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def _fill_bitmasks(
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self, batch: Iterable[tuple[StructuredOutputGrammar, int, bool]]
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) -> None:
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assert self._grammar_bitmask is not None
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for grammar, index, apply_bitmask in batch:
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if apply_bitmask and not grammar.is_terminated():
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grammar.fill_bitmask(self._grammar_bitmask, index)
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else:
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# Note that for thinking support, we will need to
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# reset the relevant part of the bitmask for consequent
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# requests here.
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self._grammar_bitmask[index].fill_(self._full_mask)
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def _async_submit_fill_bitmask(
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self, batch: list[tuple[StructuredOutputGrammar, int, bool]]
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) -> Future:
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return self.executor_for_fillmask.submit(self._fill_bitmasks, batch)
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def grammar_bitmask(
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self,
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requests: dict[str, "Request"],
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structured_output_request_ids: list[str],
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scheduled_spec_decode_tokens: dict[str, list[int]],
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) -> "npt.NDArray[np.int32] | None":
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# Prepare the structured output bitmask for this batch.
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if not structured_output_request_ids:
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return None
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# Covers both speculative decoding and diffusion LLMs (canvas_length).
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max_num_spec_tokens = self.vllm_config.num_speculative_tokens
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if self._grammar_bitmask is None:
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assert self.backend is not None
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max_batch_size = self.vllm_config.scheduler_config.max_num_seqs
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# Allocate a bitmask for each token needing to be checked:
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# one for each speculative position, and one more for the
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# bonus token / non-speculative token.
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self._grammar_bitmask = self.backend.allocate_token_bitmask(
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max_batch_size * (1 + max_num_spec_tokens)
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)
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# Generate a batched bitmask for all structured output requests.
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# When speculative decoding is enabled, we need to include multiple
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# masks for each request, one for each possible bonus token position.
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# These are stored inline in the tensor and unpacked by the gpu runner.
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cumulative_index = 0
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# Optimized parallel filling of bitmasks for
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# non-spec, large-batch-size cases
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if (
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len(structured_output_request_ids) > self.fill_bitmask_parallel_threshold
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and max_num_spec_tokens == 0
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):
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promises = []
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batch = []
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for req_id in structured_output_request_ids:
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request = requests[req_id]
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structured_output_request = request.structured_output_request
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if TYPE_CHECKING:
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assert structured_output_request is not None
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assert structured_output_request.grammar is not None
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grammar = structured_output_request.grammar
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apply_bitmask = self.should_fill_bitmask(request)
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batch.append((grammar, cumulative_index, apply_bitmask))
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if len(batch) == self.fill_bitmask_parallel_batch_size:
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promises.append(self._async_submit_fill_bitmask(batch))
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batch = []
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cumulative_index += 1
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if batch:
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promises.append(self._async_submit_fill_bitmask(batch))
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# Wait for all bitmask filling tasks to complete.
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for promise in promises:
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promise.result()
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else:
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# Fallback to serial filling of bitmasks for small-batch-size cases
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for req_id in structured_output_request_ids:
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request = requests[req_id]
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structured_output_request = request.structured_output_request
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if TYPE_CHECKING:
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assert structured_output_request is not None
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assert structured_output_request.grammar is not None
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grammar = structured_output_request.grammar
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apply_bitmask = self.should_fill_bitmask(request)
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reasoner = self._get_reasoner(request)
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detect_reasoning_end = (
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not apply_bitmask
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and reasoner is not None
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and not self.enable_in_reasoning
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)
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simulated_buf: list[int] | None = None
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history_len = 0
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state_advancements = 0
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post_reasoning_end_in_window = False
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req_tokens = scheduled_spec_decode_tokens.get(req_id, ())
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for i, token in enumerate(req_tokens):
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self._fill_bitmasks(((grammar, cumulative_index, apply_bitmask),))
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advance_grammar = apply_bitmask
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if token == -1:
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apply_bitmask = False
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advance_grammar = False
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elif (
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detect_reasoning_end
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and reasoner is not None
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and not apply_bitmask
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):
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if simulated_buf is None:
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history = list(request.all_token_ids)
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history_len = len(history)
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simulated_buf = history + list(req_tokens)
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simulated = simulated_buf[: history_len + i + 1]
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if reasoner.is_reasoning_end_streaming(simulated, [token]):
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# Reasoning ended mid-window. Constrain the rest
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# of the window via bitmask. Skip grammar advance
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# through the marker (it is reasoning content);
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# try to advance through subsequent drafts so the
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# next bitmask row reflects the post-advance state,
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# but tolerate rejection since those drafts predate
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# the bitmask and are not guaranteed valid.
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apply_bitmask = True
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advance_grammar = False
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post_reasoning_end_in_window = True
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if advance_grammar and not grammar.is_terminated():
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accepted = grammar.accept_tokens(req_id, [token])
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if accepted:
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state_advancements += 1
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elif not post_reasoning_end_in_window:
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raise AssertionError(
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(token, req_id, scheduled_spec_decode_tokens)
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)
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cumulative_index += 1
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# Diffusion LLMs don't sample a bonus token after the
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# scheduled positions, so skip its bitmask in that case.
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if not (self.vllm_config.model_config.is_diffusion and req_tokens):
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# bonus_apply must be True when the bonus-row position
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# should be grammar-constrained. Two triggers:
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# - should_fill_bitmask(request): reasoning was already
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# over at step start (or no reasoner /
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# enable_in_reasoning).
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# - apply_bitmask: reasoning ended mid-window in this
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# call and was flipped True after the marker;
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# should_fill_bitmask still returns False here because
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# reasoning_ended is only persisted later by
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# should_advance.
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bonus_apply = self.should_fill_bitmask(request) or apply_bitmask
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self._fill_bitmasks(((grammar, cumulative_index, bonus_apply),))
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cumulative_index += 1
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if state_advancements > 0:
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grammar.rollback(state_advancements)
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bitmask_tensor = self._grammar_bitmask
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if cumulative_index < bitmask_tensor.shape[0]:
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bitmask_tensor = bitmask_tensor[:cumulative_index]
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# After finishing with the xgrammar operations, we convert to
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# np.ndarray, because that is much more efficient for serialization
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# and deserialization when sending this to the GPU workers.
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return bitmask_tensor.numpy()
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def should_fill_bitmask(self, request: "Request") -> bool:
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# NOTE (Hanchen) if enable_in_reasoning is True, it means that
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# the model needs to be constrained in reasoning. So we should always
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# enable the bitmask filling.
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reasoner = self._get_reasoner(request)
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if reasoner is not None:
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if self.enable_in_reasoning:
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return True
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assert request.structured_output_request is not None
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if request.structured_output_request.reasoning_ended is None:
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# This should be removed here, but since `openai_gptoss`
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# is an independent code path, it is kept for now.
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# After unifying the `openai_gptoss` and non-`openai_gptoss` styles,
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# it can be removed.
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request.structured_output_request.reasoning_ended = (
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reasoner.is_reasoning_end(request.prompt_token_ids or [])
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)
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return request.structured_output_request.reasoning_ended
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return True
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def should_advance(self, request: "Request") -> bool:
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if not request.use_structured_output:
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return False
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# To determine whether we can advance the FSM.
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# Supports thinking usage where we skip the reasoning components.
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if TYPE_CHECKING:
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assert request.structured_output_request is not None
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assert request.structured_output_request.grammar is not None
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# by default, we should always advance
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# for cases that don't use thinking mode.
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reasoner = self._get_reasoner(request)
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if reasoner is None:
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return True
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# if the model needs structured in reasoning, we should advance
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if self.enable_in_reasoning:
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return True
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structured_req = request.structured_output_request
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if structured_req.reasoning_ended:
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return True
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# Check if reasoning ends in *this* step
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delta_from = request.num_computed_tokens - request.num_output_placeholders
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all_token_ids = request.all_token_ids
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start = (
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delta_from if delta_from >= 0 else max(len(all_token_ids) + delta_from, 0)
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)
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if reasoner.is_reasoning_end_streaming(
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all_token_ids, itertools.islice(all_token_ids, start, None)
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):
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structured_req.reasoning_ended = True
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# Reasoning just ended this step. Defer FSM advance until the next
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# pass (see reasoning_ended check above) for JSON/regex/choice/grammar:
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# advancing on the closing boundary token can accept tokens that still
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# belong to the reasoning stream. Structural tags are the only safe
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# same-step exception: they model phased output (e.g. thinking tag ->
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# answer tag), and speculative decoding must run grammar.validate_tokens
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# on draft tokens produced immediately after that transition.
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if (
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self.vllm_config.speculative_config is not None
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and structured_req.structured_output_key[0]
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== StructuredOutputOptions.STRUCTURAL_TAG
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):
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# The scheduler will advance the grammar with this step's
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# tokens right away, but the step still contains reasoning
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# content up to and including the end marker. Record where
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# it ends so trim_reasoning_for_advance() can drop it.
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structured_req.reasoning_end_token_index = (
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self._find_reasoning_end_index(reasoner, all_token_ids, start)
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)
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return True
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return False
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@staticmethod
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def _find_reasoning_end_index(
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reasoner: "ReasoningParser", all_token_ids: Sequence[int], start: int
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) -> int:
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"""Locates the last reasoning token within ``all_token_ids[start:]``.
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Returns:
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The absolute index of the token at which
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``is_reasoning_end_streaming`` first fires. Falls back to the
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final index when no single token triggers the detection (e.g.
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a multi-token marker only recognized on the full delta), which
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conservatively treats the whole step as reasoning content.
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"""
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prefix = list(itertools.islice(all_token_ids, start))
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for idx in range(start, len(all_token_ids)):
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token = all_token_ids[idx]
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prefix.append(token)
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if reasoner.is_reasoning_end_streaming(prefix, [token]):
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return idx
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return len(all_token_ids) - 1
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def trim_reasoning_for_advance(
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self, request: "Request", new_token_ids: list[int]
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) -> list[int]:
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"""Drops reasoning content from tokens about to advance the grammar.
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When reasoning ends mid-step (see should_advance), the step's output
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still contains reasoning tokens up to and including the end marker.
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Those are not grammar content: feeding them to accept_tokens makes
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the grammar reject the marker and kills the request (#44006).
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Returns:
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The suffix of ``new_token_ids`` that follows the reasoning-end
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marker. Steps fully after the boundary are returned unchanged.
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"""
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structured_req = request.structured_output_request
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if structured_req is None:
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return new_token_ids
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end_idx = structured_req.reasoning_end_token_index
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if end_idx is None:
|
|
return new_token_ids
|
|
first_idx = len(request.all_token_ids) - len(new_token_ids)
|
|
num_reasoning = end_idx + 1 - first_idx
|
|
if num_reasoning <= 0:
|
|
return new_token_ids
|
|
return new_token_ids[num_reasoning:]
|
|
|
|
def clear_backend(self) -> None:
|
|
if self.backend is not None:
|
|
self.backend.destroy()
|