YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under the BSD-style license found in the

//  LICENSE file in the root directory of this source tree. An additional grant

//  of patent rights can be found in the PATENTS file in the same directory.

//

// The following only applies to changes made to this file as part of YugaByte development.

//

// Portions Copyright (c) YugaByte, Inc.

//

// Licensed 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.

//

// Copyright (c) 2011 The LevelDB Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file. See the AUTHORS file for names of contributors.

#pragma once

#include <atomic>

#include <deque>

#include "yb/rocksdb/port/port.h"

#include "yb/rocksdb/util/mutexlock.h"

#include "yb/rocksdb/util/random.h"

#include "yb/rocksdb/env.h"

#include "yb/rocksdb/rate_limiter.h"

namespace rocksdb {

class GenericRateLimiter : public RateLimiter {

 public:

  GenericRateLimiter(int64_t refill_bytes,

      int64_t refill_period_us, int32_t fairness);

  virtual ~GenericRateLimiter();

  // This API allows user to dynamically change rate limiter's bytes per second.

  virtual void SetBytesPerSecond(int64_t bytes_per_second) override;

  // Request for token to write bytes. If this request can not be satisfied,

  // the call is blocked. Caller is responsible to make sure

  // bytes <= GetSingleBurstBytes()

  virtual void Request(const int64_t bytes, const Env::IOPriority pri) override;

  virtual int64_t GetSingleBurstBytes() const override {

    return refill_bytes_per_period_.load(std::memory_order_relaxed);

  }

  virtual int64_t GetTotalBytesThrough(

      const Env::IOPriority pri = Env::IO_TOTAL) const override {

    MutexLock g(&request_mutex_);

    if (pri == Env::IO_TOTAL) {

      return total_bytes_through_[Env::IO_LOW] +

             total_bytes_through_[Env::IO_HIGH];

    }

    return total_bytes_through_[pri];

  }

  virtual int64_t GetTotalRequests(

      const Env::IOPriority pri = Env::IO_TOTAL) const override {

    MutexLock g(&request_mutex_);

    if (pri == Env::IO_TOTAL) {

      return total_requests_[Env::IO_LOW] + total_requests_[Env::IO_HIGH];

    }

    return total_requests_[pri];

  }

 private:

  void Refill();

  int64_t CalculateRefillBytesPerPeriod(int64_t rate_bytes_per_sec) {

    return rate_bytes_per_sec * refill_period_us_ / 1000000;

  }

  // This mutex guard all internal states

  mutable port::Mutex request_mutex_;

  const int64_t refill_period_us_;

  // This variable can be changed dynamically.

  std::atomic<int64_t> refill_bytes_per_period_;

  Env* const env_;

  bool stop_;

  port::CondVar exit_cv_;

  int32_t requests_to_wait_;

  int64_t total_requests_[Env::IO_TOTAL];

  int64_t total_bytes_through_[Env::IO_TOTAL];

  int64_t available_bytes_;

  int64_t next_refill_us_;

  int32_t fairness_;

  Random rnd_;

  struct Req;

  Req* leader_;

  std::deque<Req*> queue_[Env::IO_TOTAL];

};

}  // namespace rocksdb