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b345b36620
Summary: If the user specified a small enough value for the rate limiter's bytes per second, the calculation for the number of refill bytes per period could become zero which would effectively cause the server to hang forever. Test Plan: Existing tests Reviewers: sdong, yhchiang, igor Reviewed By: igor Subscribers: leveldb, andrewkr, dhruba Differential Revision: https://reviews.facebook.net/D56631
96 lines
2.9 KiB
C++
96 lines
2.9 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include <algorithm>
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#include <atomic>
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#include <deque>
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#include "port/port.h"
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#include "util/mutexlock.h"
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#include "util/random.h"
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#include "rocksdb/env.h"
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#include "rocksdb/rate_limiter.h"
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namespace rocksdb {
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class GenericRateLimiter : public RateLimiter {
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public:
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GenericRateLimiter(int64_t refill_bytes,
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int64_t refill_period_us, int32_t fairness);
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virtual ~GenericRateLimiter();
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// This API allows user to dynamically change rate limiter's bytes per second.
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virtual void SetBytesPerSecond(int64_t bytes_per_second) override;
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// Request for token to write bytes. If this request can not be satisfied,
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// the call is blocked. Caller is responsible to make sure
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// bytes <= GetSingleBurstBytes()
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virtual void Request(const int64_t bytes, const Env::IOPriority pri) override;
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virtual int64_t GetSingleBurstBytes() const override {
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return refill_bytes_per_period_.load(std::memory_order_relaxed);
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}
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virtual int64_t GetTotalBytesThrough(
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const Env::IOPriority pri = Env::IO_TOTAL) const override {
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MutexLock g(&request_mutex_);
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if (pri == Env::IO_TOTAL) {
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return total_bytes_through_[Env::IO_LOW] +
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total_bytes_through_[Env::IO_HIGH];
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}
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return total_bytes_through_[pri];
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}
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virtual int64_t GetTotalRequests(
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const Env::IOPriority pri = Env::IO_TOTAL) const override {
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MutexLock g(&request_mutex_);
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if (pri == Env::IO_TOTAL) {
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return total_requests_[Env::IO_LOW] + total_requests_[Env::IO_HIGH];
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}
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return total_requests_[pri];
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}
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private:
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void Refill();
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int64_t CalculateRefillBytesPerPeriod(int64_t rate_bytes_per_sec) {
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return std::max(kMinRefillBytesPerPeriod,
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rate_bytes_per_sec * refill_period_us_ / 1000000);
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}
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// This mutex guard all internal states
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mutable port::Mutex request_mutex_;
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const int64_t kMinRefillBytesPerPeriod = 100;
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const int64_t refill_period_us_;
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// This variable can be changed dynamically.
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std::atomic<int64_t> refill_bytes_per_period_;
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Env* const env_;
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bool stop_;
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port::CondVar exit_cv_;
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int32_t requests_to_wait_;
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int64_t total_requests_[Env::IO_TOTAL];
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int64_t total_bytes_through_[Env::IO_TOTAL];
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int64_t available_bytes_;
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int64_t next_refill_us_;
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int32_t fairness_;
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Random rnd_;
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struct Req;
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Req* leader_;
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std::deque<Req*> queue_[Env::IO_TOTAL];
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};
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} // namespace rocksdb
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