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chat_backend/llm_be/chat_backend/utils.py
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westfarn cc45ae5808
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Persist Ollama token usage from streamed LLM responses (#16) (#38)
## Summary
- Fixes token tracking for [#16](#16): streaming chat never persisted `PromptMetric.tokens_in` / `tokens_out` (admin + account usage showed `—`).
- Drop `StrOutputParser` on async LLM/RAG/data-analysis chains so Ollama `generation_info` (`prompt_eval_count` / `eval_count`) survives; collect usage while streaming via `TokenUsageCollector`.
- Stop calling `self.close()` in `disconnect` (fixes Grafana `Unexpected ASGI message 'websocket.close'`).

## Test plan
- [x] Unit tests: `test_utils`, consumers, LLM/RAG/data-analysis services, finance quotas
- [ ] Deploy / local: send a chat prompt, confirm admin Prompt Metrics shows Tokens In/Out
- [ ] Reload Account usage card — in/out no longer `—` for new turns
- [ ] Confirm WS disconnect no longer raises double-close in logsReviewed-on: #38
2026-07-31 10:46:57 -07:00

133 lines
4.4 KiB
Python

import datetime
def is_heartbeat_payload(data) -> bool:
"""True for app-level WS keepalive frames (see FE buildHeartbeatPayload)."""
return isinstance(data, dict) and data.get("type") == "ping"
def normalize_user_message(message):
"""Return stripped message text, or None if missing/blank."""
if message is None:
return None
if not isinstance(message, str):
message = str(message)
stripped = message.strip()
return stripped or None
def has_usable_user_prompt(message, file=None) -> bool:
"""Reject empty/whitespace chat text. ``file`` kept for call-site clarity."""
return normalize_user_message(message) is not None
def last_day_of_month(any_day):
# The day 28 exists in every month. 4 days later, it's always next month
next_month = any_day.replace(day=28) + datetime.timedelta(days=4)
# subtracting the number of the current day brings us back one month
return next_month - datetime.timedelta(days=next_month.day)
# Keys different providers use for input/output token counts. We only ever read
# real usage the provider reports; we never estimate, so absence maps to None.
_TOKENS_IN_KEYS = ("input_tokens", "prompt_tokens", "prompt_eval_count")
_TOKENS_OUT_KEYS = ("output_tokens", "completion_tokens", "eval_count")
def _first_int(mapping, keys):
for key in keys:
value = mapping.get(key)
if isinstance(value, bool):
continue
if isinstance(value, int):
return value
if isinstance(value, float) and value.is_integer():
return int(value)
return None
def _as_usage_mapping(source):
"""Best-effort pull of a usage dict out of a provider response.
Accepts a raw dict, a LangChain message (``usage_metadata`` /
``response_metadata``), an Ollama ``GenerationChunk`` (``generation_info``),
or any object exposing those attributes.
"""
if source is None:
return None
if isinstance(source, dict):
for nested_key in ("usage_metadata", "usage", "token_usage"):
nested = source.get(nested_key)
if isinstance(nested, dict):
return nested
return source
for attr in ("usage_metadata", "response_metadata", "generation_info"):
nested = getattr(source, attr, None)
if isinstance(nested, dict):
mapping = _as_usage_mapping(nested)
if mapping:
return mapping
return None
def extract_token_usage(source):
"""Return ``(tokens_in, tokens_out)`` from a provider usage payload.
Values are only returned when the provider actually reports them; anything
missing comes back as ``None`` so callers never persist estimated counts.
"""
mapping = _as_usage_mapping(source)
if not mapping:
return None, None
return _first_int(mapping, _TOKENS_IN_KEYS), _first_int(mapping, _TOKENS_OUT_KEYS)
def chunk_text(chunk) -> str:
"""Pull display text out of a stream chunk (str, GenerationChunk, message)."""
if chunk is None:
return ""
if isinstance(chunk, str):
return chunk
text = getattr(chunk, "text", None)
if isinstance(text, str) and text:
return text
content = getattr(chunk, "content", None)
if isinstance(content, str):
return content
return ""
class TokenUsageCollector:
"""Accumulate provider-reported token counts while streaming LLM chunks."""
def __init__(self):
self.tokens_in = None
self.tokens_out = None
def observe(self, source) -> None:
tin, tout = extract_token_usage(source)
if tin is not None:
self.tokens_in = tin
if tout is not None:
self.tokens_out = tout
@property
def pair(self):
return self.tokens_in, self.tokens_out
async def aiter_text_chunks(stream, collector: TokenUsageCollector | None = None):
"""Yield text from a provider stream, optionally capturing token usage.
Ollama reports ``prompt_eval_count`` / ``eval_count`` on the final
``GenerationChunk.generation_info`` when ``done`` is true. ``StrOutputParser``
strips that metadata, so callers must stream the raw LLM chain and use this
helper (or equivalent) to persist real usage.
"""
async for chunk in stream:
if collector is not None:
collector.observe(chunk)
text = chunk_text(chunk)
if text:
yield text