n0mad1k
93 lines
3.1 KiB
Python
93 lines
3.1 KiB
Python
"""Exponential backoff rate limiter with circuit breaker for Anthropic API."""
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import time
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import random
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import threading
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import logging
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from typing import Optional
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logger = logging.getLogger(__name__)
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class CircuitBreakerOpen(Exception):
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"""Raised when circuit breaker is open (too many consecutive failures)."""
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pass
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class APIRateLimiter:
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"""Exponential backoff with jitter and circuit breaker for API calls."""
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def __init__(self, base_delay: float = 1.0, max_delay: float = 60.0,
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circuit_threshold: int = 5):
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"""
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Args:
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base_delay: Initial backoff delay in seconds
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max_delay: Maximum backoff delay in seconds
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circuit_threshold: Consecutive failures before circuit opens
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"""
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self.base_delay = base_delay
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self.max_delay = max_delay
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self.circuit_threshold = circuit_threshold
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self._consecutive_failures = 0
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self._current_delay = 0.0
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self._lock = threading.Lock()
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@property
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def is_circuit_open(self) -> bool:
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return self._consecutive_failures >= self.circuit_threshold
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def record_success(self):
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"""Record a successful API call — reset backoff."""
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with self._lock:
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self._consecutive_failures = 0
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self._current_delay = 0.0
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def record_failure(self, error: Optional[str] = None):
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"""Record a failed API call — increase backoff."""
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with self._lock:
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self._consecutive_failures += 1
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logger.warning(
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"API failure #%d/%d: %s",
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self._consecutive_failures,
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self.circuit_threshold,
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error or "unknown"
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)
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if self.is_circuit_open:
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logger.error(
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"Circuit breaker OPEN: %d consecutive failures. "
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"Halting API calls until manual reset.",
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self._consecutive_failures
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)
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def wait_if_needed(self):
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"""Wait with exponential backoff if there have been failures. Raises CircuitBreakerOpen."""
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with self._lock:
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if self.is_circuit_open:
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raise CircuitBreakerOpen(
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f"Circuit breaker open after {self._consecutive_failures} consecutive failures. "
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f"Call reset() to retry."
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)
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if self._consecutive_failures == 0:
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return
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delay = min(
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self.base_delay * (2 ** (self._consecutive_failures - 1)),
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self.max_delay
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)
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# Add jitter (±25%)
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jitter = delay * random.uniform(-0.25, 0.25)
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actual_delay = max(0, delay + jitter)
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logger.info("API backoff: waiting %.1fs (attempt %d)",
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actual_delay, self._consecutive_failures + 1)
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# Sleep outside the lock
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time.sleep(actual_delay)
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def reset(self):
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"""Manually reset the circuit breaker."""
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with self._lock:
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self._consecutive_failures = 0
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self._current_delay = 0.0
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logger.info("Circuit breaker reset")
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