55 lines
1.8 KiB
Go
55 lines
1.8 KiB
Go
// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package eventchannel
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import (
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"github.com/golang/protobuf/proto"
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"golang.org/x/time/rate"
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)
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// rateLimitedEmitter wraps an emitter and limits events to the given limits.
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// Events that would exceed the limit are discarded.
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type rateLimitedEmitter struct {
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inner Emitter
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limiter *rate.Limiter
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}
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// RateLimitedEmitterFrom creates a new event channel emitter that wraps the
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// existing emitter and enforces rate limits. The limits are imposed via a
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// token bucket, with `maxRate` events per second, with burst size of `burst`
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// events. See the golang.org/x/time/rate package and
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// https://en.wikipedia.org/wiki/Token_bucket for more information about token
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// buckets generally.
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func RateLimitedEmitterFrom(inner Emitter, maxRate float64, burst int) Emitter {
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return &rateLimitedEmitter{
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inner: inner,
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limiter: rate.NewLimiter(rate.Limit(maxRate), burst),
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}
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}
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// Emit implements EventEmitter.Emit.
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func (rle *rateLimitedEmitter) Emit(msg proto.Message) (bool, error) {
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if !rle.limiter.Allow() {
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// Drop event.
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return false, nil
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}
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return rle.inner.Emit(msg)
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}
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// Close implements EventEmitter.Close.
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func (rle *rateLimitedEmitter) Close() error {
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return rle.inner.Close()
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}
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