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sglang/python/sglang/srt/managers/tokenizer_manager_multiitem_mixin.py

312 lines
13 KiB
Python

import logging
import math
from typing import Any, Dict, List, Optional, Union
from sglang.srt.managers.io_struct import GenerateReqInput
logger = logging.getLogger(__name__)
class TokenizerManagerMultiItemMixin:
def _initialize_multi_item_delimiter_text(self):
"""Initialize multi-item delimiter text from token ID after tokenizer is loaded."""
if (
hasattr(self.server_args, "multi_item_scoring_delimiter")
and self.server_args.multi_item_scoring_delimiter is not None
and self.tokenizer is not None
):
try:
self.multi_item_delimiter_text = self.tokenizer.decode(
[self.server_args.multi_item_scoring_delimiter],
skip_special_tokens=False,
)
except Exception as e:
logger.warning(
f"Failed to decode delimiter token {self.server_args.multi_item_scoring_delimiter}: {e}"
)
self.multi_item_delimiter_text = None
def _build_multi_item_token_sequence(
self, query: List[int], items: List[List[int]], delimiter_token_id: int
) -> List[int]:
"""
Build a single token sequence for multi-item scoring.
Format: query<delimiter>item1<delimiter>item2<delimiter>item3<delimiter>
Args:
query: Query token IDs
items: List of item token ID sequences
delimiter_token_id: Token ID to use as delimiter
Returns:
Combined token sequence
"""
combined_sequence = query[:] # Start with query
for item in items:
combined_sequence.append(delimiter_token_id) # Add delimiter
combined_sequence.extend(item) # Add item tokens
# Add final delimiter after the last item for logprob extraction
combined_sequence.append(delimiter_token_id)
return combined_sequence
def _process_multi_item_scoring_results(
self,
results: Any,
items: List,
label_token_ids: List[int],
apply_softmax: bool,
batch_request=None,
) -> List[List[float]]:
"""
Process results from multi-item scoring request.
Extracts logprobs at delimiter positions from input_token_ids_logprobs.
Args:
results: Results from generate_request
items: List of items being scored
label_token_ids: Token IDs to extract scores for
apply_softmax: Whether to apply softmax normalization
batch_request: The original batch request containing input sequence
Returns:
List of score lists, one for each item
"""
single_result = results[0] if isinstance(results, list) else results
# For multi-item scoring, logprobs are in input_token_ids_logprobs
input_logprobs = single_result["meta_info"].get("input_token_ids_logprobs", [])
if not input_logprobs:
raise RuntimeError(
f"input_token_ids_logprobs is empty for multi-item scoring request {single_result['meta_info'].get('id', '<unknown>')}. "
"This indicates token_ids_logprobs were not computed properly for Mutil Item Scoring."
)
scores = []
num_items = len(items) if isinstance(items, list) else 1
# Check if we have the expected number of logprobs
expected_logprobs_count = num_items + 1
if len(input_logprobs) != expected_logprobs_count:
raise RuntimeError(
f"Expected {expected_logprobs_count} input_token_ids_logprobs for multi-item scoring "
f"with {num_items} items, but got {len(input_logprobs)}. "
f"Request ID: {single_result['meta_info'].get('id', '<unknown>')}"
)
# Skip the first delimiter (between query and first item) and process remaining delimiter positions
# We want to exclude the first one since it represents the boundary between query and first item, not an item boundary
start_idx = 1 if len(input_logprobs) > 1 else 0
# Process logprobs for each item position (excluding first delimiter)
for item_idx in range(num_items):
logprob_idx = start_idx + item_idx
item_logprobs_data = input_logprobs[logprob_idx]
logprobs = self._extract_logprobs_for_tokens(
item_logprobs_data, label_token_ids
)
score_list = self._convert_logprobs_to_scores(
logprobs, label_token_ids, apply_softmax
)
scores.append(score_list)
return scores
def _process_single_item_scoring_results(
self, results: Any, label_token_ids: List[int], apply_softmax: bool
) -> List[List[float]]:
"""
Process results from single-item scoring request.
Single-item scoring results are stored in output_token_ids_logprobs.
Args:
results: Results from generate_request
label_token_ids: Token IDs to extract scores for
apply_softmax: Whether to apply softmax normalization
Returns:
List of score lists, one for each result
"""
scores = []
for result in results:
# For single-item scoring, logprobs are in output_token_ids_logprobs
output_logprobs = result["meta_info"].get("output_token_ids_logprobs", [])
if not output_logprobs or len(output_logprobs) == 0:
raise RuntimeError(
f"output_logprobs is empty for request {result['meta_info'].get('id', '<unknown>')}."
)
# Extract logprobs for the first (and only) position
logprobs = self._extract_logprobs_for_tokens(
output_logprobs[0], label_token_ids
)
score_list = self._convert_logprobs_to_scores(
logprobs, label_token_ids, apply_softmax
)
scores.append(score_list)
return scores
async def score_request(
self,
query: Optional[Union[str, List[int]]] = None,
items: Optional[Union[str, List[str], List[List[int]]]] = None,
label_token_ids: Optional[List[int]] = None,
apply_softmax: bool = False,
item_first: bool = False,
request: Optional[Any] = None,
) -> List[List[float]]:
"""
Score the probability of specified token IDs appearing after the given (query + item) pair.
This method supports two scoring approaches:
1. Single-Item scoring (default): Process each query+item pair independently
2. Multi-Item scoring: When multi_item_scoring_delimiter is set, combine query and
multiple items into a single sequence using delimiter for efficient processing.
Note: item_first parameter is ignored in multi-item scoring mode since it uses
a fixed format: query<delimiter>item1<delimiter>item2<delimiter>item3<delimiter>
Multi-item scoring works with both text and pre-tokenized inputs:
- Text: query<delimiter_text>item1<delimiter_text>item2<delimiter_text>item3<delimiter_text>
- Tokens: query<delimiter_token_id>item1<delimiter_token_id>item2<delimiter_token_id>item3<delimiter_token_id>
Args:
query: The query text or pre-tokenized query token IDs
items: The item text(s) or pre-tokenized item token IDs
label_token_ids: List of token IDs to compute probabilities for
apply_softmax: Whether to normalize probabilities using softmax
item_first: If True, prepend items to query. Ignored for multi-item scoring.
request: Optional FastAPI request object
Returns:
List of lists containing probabilities for each item and each label token
"""
if label_token_ids is None:
raise ValueError("label_token_ids must be provided")
if self.tokenizer is not None:
vocab_size = self.tokenizer.vocab_size
for token_id in label_token_ids:
if token_id >= vocab_size:
raise ValueError(
f"Token ID {token_id} is out of vocabulary (vocab size: {vocab_size})"
)
# Check if multi-item scoring is enabled by presence of delimiter
use_multi_item_scoring = (
self.server_args.multi_item_scoring_delimiter is not None
and self.multi_item_delimiter_text is not None
)
batch_request = GenerateReqInput(
token_ids_logprob=label_token_ids,
return_logprob=True,
# Set logprob_start_len=0 for multi-item scoring since we want logprobs at all delimiter positions
logprob_start_len=0 if use_multi_item_scoring else -1,
stream=False,
sampling_params={"max_new_tokens": 0},
)
# Handle string or tokenized query/items
if isinstance(query, str) and (
isinstance(items, str)
or (isinstance(items, list) and (not items or isinstance(items[0], str)))
):
# Both query and items are text
items_list = [items] if isinstance(items, str) else items
if use_multi_item_scoring:
# Multi-item scoring: create single prompt with delimiter text
# Always use format: query<delimiter>item1<delimiter>item2<delimiter>item3<delimiter>
# (item_first is ignored for multi-item scoring)
delimiter = self.multi_item_delimiter_text
combined_items = delimiter.join(items_list)
# Add final delimiter after the last item for logprob extraction
single_prompt = f"{query}{delimiter}{combined_items}{delimiter}"
batch_request.text = [single_prompt]
else:
# Single-item scoring: create separate prompts for each item
if item_first:
prompts = [f"{item}{query}" for item in items_list]
else:
prompts = [f"{query}{item}" for item in items_list]
batch_request.text = prompts
elif (
isinstance(query, list)
and isinstance(items, list)
and items
and isinstance(items[0], list)
):
# Both query and items are token IDs
if use_multi_item_scoring:
# Multi-item scoring: concatenate with delimiter token ID
# Format: query<delimiter_token_id>item1<delimiter_token_id>item2<delimiter_token_id>item3<delimiter_token_id>
delimiter_token_id = self.server_args.multi_item_scoring_delimiter
combined_input_ids = self._build_multi_item_token_sequence(
query, items, delimiter_token_id
)
batch_request.input_ids = [combined_input_ids]
else:
# Single-item scoring: process each item separately
if item_first:
input_ids_list = [item + query for item in items]
else:
input_ids_list = [query + item for item in items]
batch_request.input_ids = input_ids_list
else:
raise ValueError(
"Invalid combination of query/items types for score_request."
)
results = await self.generate_request(batch_request, request).__anext__()
if use_multi_item_scoring:
# Multi-item scoring: extract scores from input_token_ids_logprobs
return self._process_multi_item_scoring_results(
results, items, label_token_ids, apply_softmax, batch_request
)
else:
# Single-item scoring: process each result separately
return self._process_single_item_scoring_results(
results, label_token_ids, apply_softmax
)
def _convert_logprobs_to_scores(
self,
logprobs: Dict[int, float],
label_token_ids: List[int],
apply_softmax: bool,
) -> List[float]:
"""
Convert logprobs dictionary to ordered score list.
Args:
logprobs: Dictionary mapping token_id to logprob
label_token_ids: Token IDs in desired order
apply_softmax: Whether to apply softmax normalization
Returns:
List of scores in the same order as label_token_ids
"""
import torch
score_list = [
logprobs.get(token_id, float("-inf")) for token_id in label_token_ids
]
if apply_softmax:
score_list = torch.softmax(torch.tensor(score_list), dim=0).tolist()
else:
# Convert logprobs to probabilities if not using softmax
score_list = [
math.exp(x) if x != float("-inf") else 0.0 for x in score_list
]
return score_list