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 "yb/rocksdb/env.h"

namespace rocksdb {

class RateLimiter {

 public:

  virtual ~RateLimiter() {}

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

  // REQUIRED: bytes_per_second > 0

  virtual void SetBytesPerSecond(int64_t bytes_per_second) = 0;

  // 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) = 0;

  // Max bytes can be granted in a single burst

  virtual int64_t GetSingleBurstBytes() const = 0;

  // Total bytes that go though rate limiter

  virtual int64_t GetTotalBytesThrough(

      const Env::IOPriority pri = Env::IO_TOTAL) const = 0;

  // Total # of requests that go though rate limiter

  virtual int64_t GetTotalRequests(

      const Env::IOPriority pri = Env::IO_TOTAL) const = 0;

};

// Create a RateLimiter object, which can be shared among RocksDB instances to

// control write rate of flush and compaction.

// @rate_bytes_per_sec: this is the only parameter you want to set most of the

// time. It controls the total write rate of compaction and flush in bytes per

// second. Currently, RocksDB does not enforce rate limit for anything other

// than flush and compaction, e.g. write to WAL.

// @refill_period_us: this controls how often tokens are refilled. For example,

// when rate_bytes_per_sec is set to 10MB/s and refill_period_us is set to

// 100ms, then 1MB is refilled every 100ms internally. Larger value can lead to

// burstier writes while smaller value introduces more CPU overhead.

// The default should work for most cases.

// @fairness: RateLimiter accepts high-pri requests and low-pri requests.

// A low-pri request is usually blocked in favor of hi-pri request. Currently,

// RocksDB assigns low-pri to request from compaciton and high-pri to request

// from flush. Low-pri requests can get blocked if flush requests come in

// continuouly. This fairness parameter grants low-pri requests permission by

// 1/fairness chance even though high-pri requests exist to avoid starvation.

// You should be good by leaving it at default 10.

extern RateLimiter* NewGenericRateLimiter(

    int64_t rate_bytes_per_sec,

    int64_t refill_period_us = 100 * 1000,

    int32_t fairness = 10);

}  // namespace rocksdb