| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| #ifndef PERF_RATELIMITER_H_ |
| #define PERF_RATELIMITER_H_ |
| |
| #include <chrono> |
| #include <thread> |
| #include <mutex> |
| |
| namespace pulsar { |
| |
| class RateLimiter { |
| public: |
| RateLimiter(double rate); |
| |
| void acquire(); |
| |
| void acquire(int permits); |
| |
| private: |
| RateLimiter(const RateLimiter&); |
| RateLimiter& operator=(const RateLimiter&); |
| typedef std::chrono::high_resolution_clock Clock; |
| Clock::duration interval_; |
| |
| long storedPermits_; |
| double maxPermits_; |
| Clock::time_point nextFree_; |
| std::mutex mutex_; |
| typedef std::unique_lock<std::mutex> Lock; |
| }; |
| |
| RateLimiter::RateLimiter(double rate) |
| : interval_(std::chrono::microseconds((long)(1e6 / rate))), |
| storedPermits_(0.0), |
| maxPermits_(rate), |
| nextFree_(Clock::now()) { |
| assert(rate < 1e6 && "Exceeded maximum rate"); |
| } |
| |
| void RateLimiter::acquire() { acquire(1); } |
| |
| void RateLimiter::acquire(int permits) { |
| Clock::time_point now = Clock::now(); |
| |
| Lock lock(mutex_); |
| |
| if (now > nextFree_) { |
| storedPermits_ = std::min<long>(maxPermits_, storedPermits_ + (now - nextFree_) / interval_); |
| nextFree_ = now; |
| } |
| |
| Clock::duration wait = nextFree_ - now; |
| |
| // Determine how many stored and fresh permits to consume |
| long stored = std::min<long>(permits, storedPermits_); |
| long fresh = permits - stored; |
| |
| // In the general RateLimiter, stored permits have no wait time, |
| // and thus we only have to wait for however many fresh permits we consume |
| Clock::duration next = fresh * interval_; |
| nextFree_ += next; |
| storedPermits_ -= stored; |
| |
| lock.unlock(); |
| |
| if (wait != Clock::duration::zero()) { |
| std::this_thread::sleep_for(wait); |
| } |
| } |
| |
| } // namespace pulsar |
| |
| #endif /* PERF_RATELIMITER_H_ */ |