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076156e | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 | """
UI-agnostic retry / failure-state logic.
`stream_with_retries` turns a stream (or its failure) into a sequence of
Events. A UI only has to render events; it never catches exceptions.
"""
import math
import random
import time
from dataclasses import dataclass
from typing import Callable, Iterator, Optional
from providers import (ProviderError, RateLimitError, RefusalError,
RequestTimeoutError, StallError, with_watchdog)
@dataclass
class Event:
kind: str # start | chunk | retry_wait | done | stalled | refused | error
text: str = "" # accumulated response text so far
message: str = ""
seconds: int = 0 # for retry_wait: seconds remaining
attempt: int = 0
status_code: Optional[int] = None
def backoff_seconds(attempt: int, retry_after: Optional[float] = None,
base: float = 2.0, cap: float = 30.0) -> int:
"""Honor the server's Retry-After if present; otherwise exponential
backoff with jitter (so many clients don't retry in lockstep)."""
if retry_after:
return math.ceil(retry_after)
return math.ceil(min(cap, base * 2 ** (attempt - 1)) * random.uniform(0.75, 1.25))
def stream_with_retries(make_stream: Callable[[], Iterator[str]], *,
max_retries: int = 3,
stall_seconds: Optional[float] = None,
sleep: Callable[[float], None] = time.sleep) -> Iterator[Event]:
attempt = 0
while True:
attempt += 1
text = ""
yield Event("start", attempt=attempt)
try:
stream = make_stream()
if stall_seconds:
stream = with_watchdog(stream, stall_seconds)
for chunk in stream:
text += chunk
yield Event("chunk", text=text, attempt=attempt)
yield Event("done", text=text, attempt=attempt)
return
except RateLimitError as e:
if attempt > max_retries:
yield Event("error", text=text, attempt=attempt, status_code=429,
message=f"Still rate limited after {attempt} attempts. Giving up.")
return
wait = backoff_seconds(attempt, e.retry_after)
source = "Retry-After header" if e.retry_after else "exponential backoff + jitter"
yield Event("retry_wait", text=text, attempt=attempt, seconds=wait, status_code=429,
message=f"429 on attempt {attempt}. Waiting {wait}s ({source}).")
for left in range(wait, 0, -1):
yield Event("retry_wait", text=text, attempt=attempt, seconds=left,
status_code=429, message="")
sleep(1)
except StallError as e:
yield Event("stalled", text=text, attempt=attempt, message=str(e))
return
except RefusalError as e:
yield Event("refused", text=text, attempt=attempt, message=str(e))
return
except RequestTimeoutError as e:
yield Event("error", text=text, attempt=attempt,
message=f"No response from the API: {e}")
return
except ProviderError as e:
yield Event("error", text=text, attempt=attempt,
status_code=e.status_code, message=str(e))
return
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