rocksdb/util/rate_limiter.h
Hui Xiao b25f2afeff Return Status::NotSupported() in RateLimiter::GetTotalPendingRequests default impl (#8950)
Summary:
Context:
After more discussion, a fix in https://github.com/facebook/rocksdb/issues/8938 might turn out to be too restrictive for the case where `GetTotalPendingRequests` might be invoked on RateLimiter classes that does not support the recently added API `RateLimiter::GetTotalPendingRequests` (https://github.com/facebook/rocksdb/issues/8890) due to the `assert(false)` in https://github.com/facebook/rocksdb/issues/8938. Furthermore, sentinel value like `-1` proposed in https://github.com/facebook/rocksdb/issues/8938 is easy to be ignored and unchecked. Therefore we decided to adopt `Status::NotSupported()`, which is also a convention of adding new API to public header in RocksDB.
- Changed return value type of  `RateLimiter::GetTotalPendingRequests` in related declaration/definition
- Passed in pointer argument to hold the output instead of returning it as before
- Adapted to the changes above in calling `RateLimiter::GetTotalPendingRequests` in test
- Minor improvement to `TEST_F(RateLimiterTest, GetTotalPendingRequests)`:  added failure message for assertion and replaced repetitive statements with a loop

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8950

Reviewed By: ajkr, pdillinger

Differential Revision: D31128450

Pulled By: hx235

fbshipit-source-id: 282ac9c4f3dacaa0aec6d0a993161f77ad47a040
2021-09-22 19:36:06 -07:00

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4.3 KiB
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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root 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 <algorithm>
#include <atomic>
#include <chrono>
#include <deque>
#include "port/port.h"
#include "rocksdb/env.h"
#include "rocksdb/rate_limiter.h"
#include "rocksdb/status.h"
#include "rocksdb/system_clock.h"
#include "util/mutexlock.h"
#include "util/random.h"
namespace ROCKSDB_NAMESPACE {
class GenericRateLimiter : public RateLimiter {
public:
GenericRateLimiter(int64_t refill_bytes, int64_t refill_period_us,
int32_t fairness, RateLimiter::Mode mode,
const std::shared_ptr<SystemClock>& clock,
bool auto_tuned);
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()
using RateLimiter::Request;
virtual void Request(const int64_t bytes, const Env::IOPriority pri,
Statistics* stats) 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) {
int64_t total_bytes_through_sum = 0;
for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
total_bytes_through_sum += total_bytes_through_[i];
}
return total_bytes_through_sum;
}
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) {
int64_t total_requests_sum = 0;
for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
total_requests_sum += total_requests_[i];
}
return total_requests_sum;
}
return total_requests_[pri];
}
virtual Status GetTotalPendingRequests(
int64_t* total_pending_requests,
const Env::IOPriority pri = Env::IO_TOTAL) const override {
assert(total_pending_requests != nullptr);
MutexLock g(&request_mutex_);
if (pri == Env::IO_TOTAL) {
int64_t total_pending_requests_sum = 0;
for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
total_pending_requests_sum += static_cast<int64_t>(queue_[i].size());
}
*total_pending_requests = total_pending_requests_sum;
} else {
*total_pending_requests = static_cast<int64_t>(queue_[pri].size());
}
return Status::OK();
}
virtual int64_t GetBytesPerSecond() const override {
return rate_bytes_per_sec_;
}
private:
void RefillBytesAndGrantRequests();
std::vector<Env::IOPriority> GeneratePriorityIterationOrder();
int64_t CalculateRefillBytesPerPeriod(int64_t rate_bytes_per_sec);
Status Tune();
uint64_t NowMicrosMonotonic() { return clock_->NowNanos() / std::milli::den; }
// This mutex guard all internal states
mutable port::Mutex request_mutex_;
const int64_t kMinRefillBytesPerPeriod = 100;
const int64_t refill_period_us_;
int64_t rate_bytes_per_sec_;
// This variable can be changed dynamically.
std::atomic<int64_t> refill_bytes_per_period_;
std::shared_ptr<SystemClock> clock_;
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;
std::deque<Req*> queue_[Env::IO_TOTAL];
bool wait_until_refill_pending_;
bool auto_tuned_;
int64_t num_drains_;
int64_t prev_num_drains_;
const int64_t max_bytes_per_sec_;
std::chrono::microseconds tuned_time_;
};
} // namespace ROCKSDB_NAMESPACE