rocksdb/util/rate_limiter.h
2016-02-09 15:12:00 -08:00

92 lines
2.7 KiB
C++

// 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.
//
// 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 "port/port.h"
#include "util/mutexlock.h"
#include "util/random.h"
#include "rocksdb/env.h"
#include "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