/usr/include/rocksdb/rate_limiter.h is in librocksdb-dev 4.5.1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// 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.
//
// 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 "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
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