risingwave_stream/common/
rate_limit.rs

1// Copyright 2024 RisingWave Labs
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use futures_async_stream::stream;
16use risingwave_common::array::StreamChunk;
17use risingwave_common_rate_limit::{RateLimit, RateLimiter};
18
19/// Get the rate-limited max chunk size.
20pub(crate) fn limited_chunk_size(rate_limit_burst: Option<u32>) -> usize {
21    let config_chunk_size = crate::config::chunk_size();
22    rate_limit_burst
23        .map(|burst| config_chunk_size.min(burst as usize))
24        .unwrap_or(config_chunk_size)
25}
26
27/// Yield `chunk` under the limiter's current policy, split into pieces no larger than the rate
28/// so that a policy update takes effect within about a second.
29#[stream(item = StreamChunk)]
30pub(crate) async fn rate_limited_pieces(limiter: &RateLimiter, chunk: StreamChunk) {
31    if chunk.capacity() == 0 {
32        yield chunk;
33        return;
34    }
35    let rate_limit = loop {
36        match limiter.rate_limit() {
37            RateLimit::Pause => limiter.wait(0).await,
38            limit => break limit,
39        }
40    };
41    match rate_limit {
42        RateLimit::Pause => unreachable!(),
43        RateLimit::Disabled => yield chunk,
44        RateLimit::Fixed(limit) => {
45            let max_permits = limit.get();
46            if chunk.rate_limit_permits() <= max_permits {
47                limiter.wait(chunk.rate_limit_permits()).await;
48                yield chunk;
49            } else {
50                for piece in chunk.split(max_permits as _) {
51                    limiter.wait_chunk(&piece).await;
52                    yield piece;
53                }
54            }
55        }
56    }
57}
risingwave_stream/common/rate_limit.rs

risingwave_stream/common/
rate_limit.rs
