Bug: Async rate limiting fails with 'async call made without an async bucket'

[dgunning]

Description

When using async_http_client() for async HTTP requests, the rate limiter fails with:

async call made without an async bucket

This occurs because create_rate_limiter() in ratelimiter.py creates an InMemoryBucket, which doesn't support async operations in pyrate-limiter 3.x.

Steps to Reproduce

from httpxthrottlecache import HttpxThrottleCache
import asyncio

mgr = HttpxThrottleCache(request_per_sec_limit=9)

async def test():
    async with mgr.async_http_client() as client:
        response = await client.get("https://httpbin.org/get")
        print(response.status_code)

asyncio.run(test())

Output:

async call made without an async bucket.

Root Cause

In ratelimiter.py:14-24:

def create_rate_limiter(requests_per_second: int, max_delay: Duration | int = Duration.DAY) -> Limiter:
    rate = Rate(requests_per_second, Duration.SECOND)
    rate_limits = [rate]
    base_bucket = InMemoryBucket(rate_limits)  # <-- sync-only bucket
    bucket = base_bucket
    limiter = Limiter(bucket, max_delay=max_delay, raise_when_fail=False, retry_until_max_delay=True)
    return limiter

InMemoryBucket from pyrate-limiter 3.x doesn't have async support. When AsyncRateLimitingTransport.handle_async_request() calls limiter.try_acquire_async(), it fails.

Suggested Fix

Use BucketAsyncWrapper to wrap the bucket for async support:

from pyrate_limiter import InMemoryBucket, BucketAsyncWrapper, Limiter, Rate, Duration

def create_rate_limiter(requests_per_second: int, max_delay: Duration | int = Duration.DAY) -> Limiter:
    rate = Rate(requests_per_second, Duration.SECOND)
    base_bucket = InMemoryBucket([rate])
    async_bucket = BucketAsyncWrapper(base_bucket)
    return Limiter(async_bucket, max_delay=max_delay, raise_when_fail=False, retry_until_max_delay=True)

Note: BucketAsyncWrapper requires a running event loop when created, so this may need to be lazily initialized or created differently.

Environment

• httpxthrottlecache: 0.3.0
• pyrate-limiter: 3.9.0
• Python: 3.11

Impact

This bug prevents using httpxthrottlecache for any async HTTP operations, which is a significant limitation for libraries that need both sync and async support.