mirror of
https://github.com/BerriAI/litellm.git
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30c6241e3a
Every OpenAI Responses body carries `error: null` at the top level, and the completeness check tested the key's presence rather than its value, so it rejected every single one. The cost was silent: nothing failed, the endpoint simply never cached, which is exactly the outcome the endpoint was added for. Found by driving the edge against the real providers rather than the synthetic fixtures, which carried no error key at all. Reading the value instead of the key is also more accurate for chat completions and messages, where a real error body carries a populated error object.
448 lines
18 KiB
Python
448 lines
18 KiB
Python
from __future__ import annotations
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import base64
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import hashlib
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import hmac
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import io
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import threading
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import time
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from collections.abc import Callable, Generator, Mapping
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from contextlib import closing
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from dataclasses import dataclass, field
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from types import MappingProxyType
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from typing import Final, Literal, Protocol
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from urllib.parse import urlsplit
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from e2e_http import (
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NetworkError,
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StreamChunk,
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StreamHead,
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StreamStep,
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StreamTruncation,
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forward_prepared_stream,
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forward_stream,
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prepare_forward,
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primed_steps,
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)
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from fixture_canonical import MARKER_PATTERN, MARKER_PLACEHOLDER
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from fixture_mode import SESSION_TEST_KEY, current_test_key
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from pydantic import BaseModel, ConfigDict, JsonValue, TypeAdapter, ValidationError
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LIFETIME_SECONDS: Final = 86_400
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MAX_REQUEST_BYTES: Final = 256 * 1024
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MAX_RESPONSE_BYTES: Final = 8 * 1024 * 1024
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UNRECORDED_RESPONSE_HEADERS: Final = frozenset({"set-cookie"})
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SIGNATURE_HEADERS: Final = frozenset(
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{"authorization", "x-amz-date", "x-amz-security-token", "x-amz-content-sha256"}
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)
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BEDROCK_MOUNT_PREFIX: Final = "bedrock"
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OPENAI_JSON_PATHS: Final = frozenset({"/v1/chat/completions", "/v1/messages", "/v1/embeddings", "/v1/responses"})
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JSON_VALUE: Final[TypeAdapter[JsonValue]] = TypeAdapter(JsonValue)
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@dataclass(frozen=True, slots=True)
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class CacheHit:
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payload: bytes
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valid_until: float
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@dataclass(frozen=True, slots=True)
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class CaptureLease:
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token: str
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captured_at_ms: int
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expires_at_ms: int
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@dataclass(frozen=True, slots=True)
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class CacheBusy:
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pass
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@dataclass(frozen=True, slots=True)
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class CacheUnavailable:
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pass
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type CacheLookup = CacheHit | CaptureLease | CacheBusy | CacheUnavailable
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type RequestSigner = Callable[[str, str, Mapping[str, str], bytes | None], dict[str, str]]
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@dataclass(frozen=True, slots=True)
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class MountPolicy:
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"""What a mount needs beyond plain forwarding.
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``sign`` mints a fresh credential over the upstream URL, for providers whose
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auth covers the Host the edge rewrote. ``unkeyed_headers`` names headers that
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must stay out of the cache key because they change on every call and would
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otherwise make the mount a permanent miss: a minted signature, or an OAuth
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token the provider rotates. Naming one costs the guarantee that a recording
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can never cross credentials, so a mount with a rotating token relies on the
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environment holding one identity for that provider. Mounts with a static API
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key name nothing here and keep the guarantee whole."""
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sign: RequestSigner | None = None
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unkeyed_headers: frozenset[str] = frozenset()
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class ResponseStore(Protocol):
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def lookup(self, key: str) -> CacheLookup: ...
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def publish(self, key: str, lease: CaptureLease, payload: bytes) -> bool: ...
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def release(self, key: str, lease: CaptureLease) -> bool: ...
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def discard(self, key: str, payload: bytes) -> bool: ...
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class CachedResponse(BaseModel):
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model_config = ConfigDict(frozen=True, extra="forbid", strict=True)
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format_version: Literal[1] = 1
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request_key: str
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status_code: int
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headers: dict[str, str]
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chunks: tuple[str, ...]
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class SignedResponse(BaseModel):
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model_config = ConfigDict(frozen=True, extra="forbid", strict=True)
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response: str
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signature: str
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def canonical_text(value: str) -> str:
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return MARKER_PATTERN.sub(MARKER_PLACEHOLDER, value)
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def canonical_body(body: bytes) -> bytes:
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try:
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return canonical_text(body.decode("utf-8")).encode("utf-8")
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except UnicodeDecodeError:
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return body
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def request_identity(
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secret: bytes, test_key: str, method: str, url: str, headers: Mapping[str, str], body: bytes | None,
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) -> str:
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fields: Final = (
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b"provider-cache-canonical-v2", test_key.encode(), method.encode(), canonical_text(url).encode(),
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*(part.encode() for pair in sorted(headers.items()) for part in pair),
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b"no-body" if body is None else b"body", b"" if body is None else canonical_body(body),
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)
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encoded: Final = b"".join(len(part).to_bytes(8, "big") + part for part in fields)
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return hmac.new(secret, encoded, hashlib.sha256).hexdigest()
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def slotted_key(secret: bytes, identity: str, slot: int) -> str:
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return hmac.new(secret, f"{identity}:{slot}".encode(), hashlib.sha256).hexdigest()
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def is_bedrock(mount: str) -> bool:
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return mount.partition("/")[0] == BEDROCK_MOUNT_PREFIX
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def cacheable_endpoint(mount: str, method: str, url: str, body: bytes | None) -> bool:
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if method != "POST" or body is None or len(body) > MAX_REQUEST_BYTES:
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return False
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path: Final = urlsplit(url).path
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if is_bedrock(mount):
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return path.startswith("/model/") and path.endswith(("/converse", "/invoke"))
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return path in OPENAI_JSON_PATHS
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def successful_response(mount: str, url: str, status: int, headers: Mapping[str, str], body: bytes) -> bool:
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if not 200 <= status < 300 or len(body) > MAX_RESPONSE_BYTES:
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return False
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if is_bedrock(mount):
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return complete_bedrock_response(url, body)
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streaming: Final = "text/event-stream" in headers.get("content-type", "").lower()
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if streaming:
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try:
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text: Final = body.decode("utf-8").replace("\r\n", "\n")
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if not text.endswith("\n\n"):
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return False
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events: Final = tuple(
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"\n".join(line[5:].removeprefix(" ") for line in event.split("\n") if line.startswith("data:"))
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for event in text.split("\n\n") if any(line.startswith("data:") for line in event.split("\n"))
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)
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values: Final = tuple(JSON_VALUE.validate_json(event) for event in events if event != "[DONE]")
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except (UnicodeDecodeError, ValidationError):
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return False
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if not values or any(
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not isinstance(value, dict) or value.get("error") is not None or value.get("type") == "error"
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for value in values
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):
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return False
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if urlsplit(url).path == "/v1/responses":
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return complete_responses_stream(values)
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if urlsplit(url).path == "/v1/chat/completions":
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return events[-1] == "[DONE]" and "[DONE]" not in events[:-1] and complete_chat_stream(values)
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return (
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"[DONE]" not in events
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and isinstance(values[0], dict) and values[0].get("type") == "message_start"
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and isinstance(values[-1], dict) and values[-1].get("type") == "message_stop"
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and any(
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isinstance(value, dict) and value.get("type") == "message_delta"
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and isinstance(delta := value.get("delta"), dict) and isinstance(delta.get("stop_reason"), str)
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for value in values
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)
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)
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try:
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value: Final = JSON_VALUE.validate_json(body)
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except ValidationError:
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return False
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if not isinstance(value, dict) or value.get("error") is not None:
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return False
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path: Final = urlsplit(url).path
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if path == "/v1/messages":
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return value.get("type") == "message" and isinstance(value.get("content"), list) and isinstance(value.get("stop_reason"), str)
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if path == "/v1/embeddings":
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data: Final = value.get("data")
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return isinstance(data, list) and bool(data) and isinstance(value.get("usage"), dict) and all(
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isinstance(item, dict) and isinstance(item.get("embedding"), list) and bool(item["embedding"])
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for item in data
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)
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if path == "/v1/responses":
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return value.get("object") == "response" and value.get("status") == "completed"
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choices: Final = value.get("choices")
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return isinstance(choices, list) and bool(choices) and all(
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isinstance(choice, dict) and isinstance(choice.get("message"), dict) and isinstance(choice.get("finish_reason"), str)
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for choice in choices
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)
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def complete_bedrock_response(url: str, body: bytes) -> bool:
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"""Converse answers with ``output`` plus a ``stopReason``; InvokeModel on an
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Anthropic model answers the Anthropic message shape. Either way a truncated
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or error body is missing the terminator field, which is what makes it safe to
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record. The streaming variants never reach here: they are not cacheable."""
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try:
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value: Final = JSON_VALUE.validate_json(body)
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except ValidationError:
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return False
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if not isinstance(value, dict) or "message" in value:
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return False
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if urlsplit(url).path.endswith("/converse"):
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return isinstance(value.get("output"), dict) and isinstance(value.get("stopReason"), str)
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return (
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value.get("type") == "message"
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and isinstance(value.get("content"), list)
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and isinstance(value.get("stop_reason"), str)
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)
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def complete_responses_stream(values: tuple[JsonValue, ...]) -> bool:
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"""The Responses API streams typed events and ends with ``response.completed``.
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A run that failed, was cancelled, or ran out of tokens ends with a different
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terminal event, so requiring that one keeps a half-finished response out."""
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last: Final = values[-1]
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return isinstance(last, dict) and last.get("type") == "response.completed"
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def complete_chat_stream(values: tuple[JsonValue, ...]) -> bool:
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if any(not isinstance(value, dict) or not isinstance(value.get("choices"), list) for value in values):
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return False
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choices: Final = tuple(
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choice for value in values if isinstance(value, dict)
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if isinstance(items := value.get("choices"), list) for choice in items
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)
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if not choices or any(
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not isinstance(choice, dict) or type(choice.get("index")) is not int
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or not isinstance(choice.get("delta"), dict)
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for choice in choices
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):
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return False
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indices: Final = frozenset(choice["index"] for choice in choices if isinstance(choice, dict))
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return all(
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isinstance(tuple(choice for choice in choices if isinstance(choice, dict) and choice["index"] == index)[-1].get("finish_reason"), str)
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for index in indices
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)
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def encode_response(secret: bytes, response: CachedResponse) -> bytes:
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raw: Final = response.model_dump_json()
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return SignedResponse(response=raw, signature=hmac.new(secret, raw.encode(), hashlib.sha256).hexdigest()).model_dump_json().encode()
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def decode_response(secret: bytes, key: str, payload: bytes, mount: str, url: str) -> CachedResponse | None:
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if len(payload) > 2 * MAX_RESPONSE_BYTES:
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return None
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try:
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signed: Final = SignedResponse.model_validate_json(payload)
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if not hmac.compare_digest(signed.signature.encode(), hmac.new(secret, signed.response.encode(), hashlib.sha256).hexdigest().encode()):
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return None
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response: Final = CachedResponse.model_validate_json(signed.response)
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chunks: Final = tuple(base64.b64decode(chunk, validate=True) for chunk in response.chunks)
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except (ValidationError, ValueError):
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return None
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if response.request_key != key or not successful_response(
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mount, url, response.status_code, response.headers, b"".join(chunks)
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):
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return None
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return response
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@dataclass(slots=True)
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class CacheCounters:
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counts: tuple[tuple[str, int], ...] = ()
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lock: threading.Lock = field(default_factory=threading.Lock)
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def increment(self, name: str) -> None:
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with self.lock:
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current: Final = dict(self.counts)
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self.counts = tuple((current | {name: current.get(name, 0) + 1}).items())
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@dataclass(slots=True)
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class SlotCounter:
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"""FIFO position of a request among the canonically identical ones its test
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has already sent. Two calls in one test that differ only by ``unique_marker``
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canonicalize the same, so without this they would share one recording and the
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second would replay the first's provider response id."""
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counts: tuple[tuple[str, int], ...] = ()
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lock: threading.Lock = field(default_factory=threading.Lock)
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def take(self, identity: str) -> int:
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with self.lock:
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current: Final = dict(self.counts)
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taken: Final = current.get(identity, 0)
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self.counts = tuple((current | {identity: taken + 1}).items())
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return taken
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@dataclass(slots=True)
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class ResponseCapture:
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buffer: io.BytesIO = field(default_factory=io.BytesIO)
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size: int = 0
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eligible: bool = True
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def observe(self, step: StreamStep) -> None:
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if not self.eligible:
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return
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if isinstance(step, StreamTruncation) or self.size + len(step.data) + 8 > MAX_RESPONSE_BYTES:
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self.eligible = False
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self.buffer.close()
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return
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self.buffer.write(len(step.data).to_bytes(8, "big"))
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self.buffer.write(step.data)
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self.size += len(step.data) + 8
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def chunks(self) -> tuple[bytes, ...]:
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self.buffer.seek(0)
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return tuple(self.buffer.read(int.from_bytes(size, "big")) for size in iter(lambda: self.buffer.read(8), b""))
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def response_steps(response: CachedResponse) -> Generator[StreamStep, None, None]:
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for chunk in response.chunks:
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yield StreamChunk(base64.b64decode(chunk, validate=True))
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NO_POLICIES: Final[Mapping[str, MountPolicy]] = MappingProxyType({})
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@dataclass(frozen=True, slots=True)
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class CacheEdge:
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store: ResponseStore
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secret: bytes = field(repr=False)
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counters: CacheCounters = field(default_factory=CacheCounters)
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slots: SlotCounter = field(default_factory=SlotCounter)
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policies: Mapping[str, MountPolicy] = NO_POLICIES
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wait_seconds: float = 2.0
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clock: Callable[[], float] = time.monotonic
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sleep: Callable[[float], None] = time.sleep
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test_key: Callable[[], str] = current_test_key
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def lookup(self, key: str) -> CacheLookup:
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deadline: Final = self.clock() + self.wait_seconds
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while isinstance(result := self.store.lookup(key), CacheBusy) and self.clock() < deadline:
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self.sleep(min(0.05, max(0, deadline - self.clock())))
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return result
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def count(self, mount: str, name: str) -> None:
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self.counters.increment(name)
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self.counters.increment(f"mount:{mount}:{name}")
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def outbound(self, mount: str, method: str, url: str, headers: dict[str, str], body: bytes | None) -> dict[str, str]:
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"""The headers actually sent upstream. A signing mount gets a signature
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minted over the upstream URL, because the edge rewrote the Host the proxy
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signed and the provider verifies it."""
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signer: Final = self.policies.get(mount, MountPolicy()).sign
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return headers if signer is None else signer(method, url, headers, body)
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def keyed(self, mount: str, headers: Mapping[str, str]) -> Mapping[str, str]:
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"""Headers the cache key is built from. A mount keeps its credentials in
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the key unless its policy names them unkeyed, so by default one account
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can never read another's recording."""
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unkeyed: Final = self.policies.get(mount, MountPolicy()).unkeyed_headers
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if not unkeyed:
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return headers
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return {name: value for name, value in headers.items() if name.lower() not in unkeyed}
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def forward(
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self, mount: str, method: str, url: str, headers: dict[str, str], body: bytes | None, timeout: float,
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) -> StreamHead | NetworkError:
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test_key: Final = self.test_key()
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if test_key == SESSION_TEST_KEY or not cacheable_endpoint(mount, method, url, body):
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self.count(mount, "bypass")
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self.count(mount, "upstream_attempts")
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return forward_stream(
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method, url, headers=self.outbound(mount, method, url, headers, body), body=body, timeout=timeout,
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)
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prepared: Final = prepare_forward(method, url, self.outbound(mount, method, url, headers, body), body)
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if isinstance(prepared, NetworkError):
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self.count(mount, "rejected")
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return prepared
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identity: Final = request_identity(
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self.secret, test_key, method, url, self.keyed(mount, prepared.headers), body,
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)
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key: Final = slotted_key(self.secret, identity, self.slots.take(identity))
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found: Final = self.lookup(key)
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if isinstance(found, CacheHit):
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response: Final = decode_response(self.secret, key, found.payload, mount, url)
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if response is not None and self.clock() < found.valid_until:
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self.count(mount, "hits")
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return StreamHead(response.status_code, response.headers, response_steps(response))
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self.count(mount, "corrupt" if response is None else "expired")
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self.store.discard(key, found.payload)
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capture_slot: Final = self.lookup(key) if isinstance(found, CacheHit) else found
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self.count(mount, "misses")
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if isinstance(capture_slot, CacheUnavailable):
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self.count(mount, "cache_errors")
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self.count(mount, "upstream_attempts")
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head: Final = forward_prepared_stream(prepared, timeout)
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if not isinstance(capture_slot, CaptureLease):
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return head
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if isinstance(head, NetworkError):
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self.store.release(key, capture_slot)
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self.count(mount, "rejected")
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return head
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return StreamHead(
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head.status_code, head.headers, primed_steps(self.capture(mount, key, capture_slot, url, head)),
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)
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def capture(
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self, mount: str, key: str, lease: CaptureLease, url: str, head: StreamHead,
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) -> Generator[StreamStep, None, None]:
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capture: Final = ResponseCapture()
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try:
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with closing(head.steps):
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yield StreamChunk(b"")
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for step in head.steps:
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yield step
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capture.observe(step)
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chunks: Final = capture.chunks() if capture.eligible else ()
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headers: Final = {
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name: value for name, value in head.headers.items() if name.lower() not in UNRECORDED_RESPONSE_HEADERS
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}
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if not capture.eligible or not successful_response(mount, url, head.status_code, headers, b"".join(chunks)):
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self.count(mount, "rejected")
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return
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response: Final = CachedResponse(
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request_key=key, status_code=head.status_code, headers=headers,
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chunks=tuple(base64.b64encode(chunk).decode("ascii") for chunk in chunks),
|
|
)
|
|
published: Final = self.store.publish(key, lease, encode_response(self.secret, response))
|
|
self.count(mount, "writes" if published else "write_failures")
|
|
finally:
|
|
self.store.release(key, lease)
|
|
capture.buffer.close()
|