fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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494 lines
18 KiB
494 lines
18 KiB
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root 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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#include "util/rate_limiter.h"
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#include <algorithm>
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#include "monitoring/statistics.h"
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#include "port/port.h"
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#include "rocksdb/convenience.h"
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#include "rocksdb/system_clock.h"
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#include "rocksdb/utilities/customizable_util.h"
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#include "rocksdb/utilities/object_registry.h"
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#include "rocksdb/utilities/options_type.h"
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#include "test_util/sync_point.h"
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#include "util/aligned_buffer.h"
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#include "util/string_util.h"
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namespace ROCKSDB_NAMESPACE {
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size_t RateLimiter::RequestToken(size_t bytes, size_t alignment,
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Env::IOPriority io_priority, Statistics* stats,
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RateLimiter::OpType op_type) {
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if (io_priority < Env::IO_TOTAL && IsRateLimited(op_type)) {
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bytes = std::min(bytes, static_cast<size_t>(GetSingleBurstBytes()));
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if (alignment > 0) {
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// Here we may actually require more than burst and block
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// but we can not write less than one page at a time on direct I/O
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// thus we may want not to use ratelimiter
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bytes = std::max(alignment, TruncateToPageBoundary(alignment, bytes));
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}
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Request(bytes, io_priority, stats, op_type);
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}
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return bytes;
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}
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// Pending request
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struct GenericRateLimiter::Req {
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explicit Req(int64_t _bytes, port::Mutex* _mu)
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: request_bytes(_bytes), bytes(_bytes), cv(_mu), granted(false) {}
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int64_t request_bytes;
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int64_t bytes;
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port::CondVar cv;
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bool granted;
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};
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static std::unordered_map<std::string, OptionTypeInfo>
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generic_rate_limiter_type_info = {
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#ifndef ROCKSDB_LITE
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{"rate_bytes_per_sec",
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{offsetof(struct GenericRateLimiter::GenericRateLimiterOptions,
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max_bytes_per_sec),
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OptionType::kInt64T}},
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{"refill_period_us",
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{offsetof(struct GenericRateLimiter::GenericRateLimiterOptions,
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refill_period_us),
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OptionType::kInt64T}},
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{"fairness",
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{offsetof(struct GenericRateLimiter::GenericRateLimiterOptions,
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fairness),
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OptionType::kInt32T}},
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{"auto_tuned",
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{offsetof(struct GenericRateLimiter::GenericRateLimiterOptions,
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auto_tuned),
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OptionType::kBoolean}},
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{"clock",
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OptionTypeInfo::AsCustomSharedPtr<SystemClock>(
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offsetof(struct GenericRateLimiter::GenericRateLimiterOptions,
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clock),
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OptionVerificationType::kByNameAllowFromNull,
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OptionTypeFlags::kAllowNull)},
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#endif // ROCKSDB_LITE
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};
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GenericRateLimiter::GenericRateLimiter(
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int64_t rate_bytes_per_sec, int64_t refill_period_us, int32_t fairness,
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RateLimiter::Mode mode, const std::shared_ptr<SystemClock>& clock,
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bool auto_tuned)
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: RateLimiter(mode),
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options_(rate_bytes_per_sec, refill_period_us, fairness, clock,
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auto_tuned),
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stop_(false),
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exit_cv_(&request_mutex_),
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requests_to_wait_(0),
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available_bytes_(0),
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rnd_((uint32_t)time(nullptr)),
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wait_until_refill_pending_(false),
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num_drains_(0) {
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RegisterOptions(&options_, &generic_rate_limiter_type_info);
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for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
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total_requests_[i] = 0;
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total_bytes_through_[i] = 0;
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}
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Initialize();
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}
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void GenericRateLimiter::Initialize() {
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if (options_.clock == nullptr) {
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options_.clock = SystemClock::Default();
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}
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options_.fairness = std::min(options_.fairness, 100);
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next_refill_us_ = NowMicrosMonotonic();
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tuned_time_ = std::chrono::microseconds(NowMicrosMonotonic());
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if (options_.auto_tuned) {
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rate_bytes_per_sec_ = options_.max_bytes_per_sec / 2;
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} else {
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rate_bytes_per_sec_ = options_.max_bytes_per_sec;
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}
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refill_bytes_per_period_ = CalculateRefillBytesPerPeriod(rate_bytes_per_sec_);
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}
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GenericRateLimiter::~GenericRateLimiter() {
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MutexLock g(&request_mutex_);
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stop_ = true;
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std::deque<Req*>::size_type queues_size_sum = 0;
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for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
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queues_size_sum += queue_[i].size();
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}
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requests_to_wait_ = static_cast<int32_t>(queues_size_sum);
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for (int i = Env::IO_TOTAL - 1; i >= Env::IO_LOW; --i) {
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std::deque<Req*> queue = queue_[i];
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for (auto& r : queue) {
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r->cv.Signal();
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}
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}
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while (requests_to_wait_ > 0) {
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exit_cv_.Wait();
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}
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}
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Status GenericRateLimiter::PrepareOptions(const ConfigOptions& options) {
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if (options_.fairness <= 0) {
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return Status::InvalidArgument("Fairness must be > 0");
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} else if (options_.max_bytes_per_sec <= 0) {
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return Status::InvalidArgument("max_bytes_per_sec must be > 0");
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} else if (options_.refill_period_us <= 0) {
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return Status::InvalidArgument("Refill_period_us must be > 0");
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}
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Initialize();
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return RateLimiter::PrepareOptions(options);
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}
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// This API allows user to dynamically change rate limiter's bytes per second.
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void GenericRateLimiter::SetBytesPerSecond(int64_t bytes_per_second) {
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assert(bytes_per_second > 0);
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rate_bytes_per_sec_ = bytes_per_second;
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refill_bytes_per_period_.store(
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CalculateRefillBytesPerPeriod(bytes_per_second),
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std::memory_order_relaxed);
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}
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void GenericRateLimiter::Request(int64_t bytes, const Env::IOPriority pri,
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Statistics* stats) {
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assert(bytes <= refill_bytes_per_period_.load(std::memory_order_relaxed));
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bytes = std::max(static_cast<int64_t>(0), bytes);
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TEST_SYNC_POINT("GenericRateLimiter::Request");
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TEST_SYNC_POINT_CALLBACK("GenericRateLimiter::Request:1",
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&rate_bytes_per_sec_);
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MutexLock g(&request_mutex_);
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if (options_.auto_tuned) {
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static const int kRefillsPerTune = 100;
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std::chrono::microseconds now(NowMicrosMonotonic());
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if (now - tuned_time_ >= kRefillsPerTune * std::chrono::microseconds(
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options_.refill_period_us)) {
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Status s = Tune();
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s.PermitUncheckedError(); //**TODO: What to do on error?
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}
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}
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if (stop_) {
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// It is now in the clean-up of ~GenericRateLimiter().
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// Therefore any new incoming request will exit from here
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// and not get satiesfied.
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return;
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}
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++total_requests_[pri];
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if (available_bytes_ >= bytes) {
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// Refill thread assigns quota and notifies requests waiting on
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// the queue under mutex. So if we get here, that means nobody
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// is waiting?
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available_bytes_ -= bytes;
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total_bytes_through_[pri] += bytes;
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return;
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}
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// Request cannot be satisfied at this moment, enqueue
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Req r(bytes, &request_mutex_);
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queue_[pri].push_back(&r);
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TEST_SYNC_POINT_CALLBACK("GenericRateLimiter::Request:PostEnqueueRequest",
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&request_mutex_);
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// A thread representing a queued request coordinates with other such threads.
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// There are two main duties.
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//
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// (1) Waiting for the next refill time.
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// (2) Refilling the bytes and granting requests.
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do {
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int64_t time_until_refill_us = next_refill_us_ - NowMicrosMonotonic();
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if (time_until_refill_us > 0) {
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if (wait_until_refill_pending_) {
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// Somebody is performing (1). Trust we'll be woken up when our request
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// is granted or we are needed for future duties.
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r.cv.Wait();
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} else {
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// Whichever thread reaches here first performs duty (1) as described
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// above.
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int64_t wait_until = options_.clock->NowMicros() + time_until_refill_us;
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RecordTick(stats, NUMBER_RATE_LIMITER_DRAINS);
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++num_drains_;
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wait_until_refill_pending_ = true;
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r.cv.TimedWait(wait_until);
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TEST_SYNC_POINT_CALLBACK("GenericRateLimiter::Request:PostTimedWait",
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&time_until_refill_us);
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wait_until_refill_pending_ = false;
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}
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} else {
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// Whichever thread reaches here first performs duty (2) as described
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// above.
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RefillBytesAndGrantRequests();
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if (r.granted) {
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// If there is any remaining requests, make sure there exists at least
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// one candidate is awake for future duties by signaling a front request
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// of a queue.
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for (int i = Env::IO_TOTAL - 1; i >= Env::IO_LOW; --i) {
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std::deque<Req*> queue = queue_[i];
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if (!queue.empty()) {
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queue.front()->cv.Signal();
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break;
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}
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}
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}
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}
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// Invariant: non-granted request is always in one queue, and granted
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// request is always in zero queues.
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#ifndef NDEBUG
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int num_found = 0;
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for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
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if (std::find(queue_[i].begin(), queue_[i].end(), &r) !=
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queue_[i].end()) {
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++num_found;
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}
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}
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if (r.granted) {
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assert(num_found == 0);
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} else {
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assert(num_found == 1);
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}
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#endif // NDEBUG
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} while (!stop_ && !r.granted);
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if (stop_) {
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// It is now in the clean-up of ~GenericRateLimiter().
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// Therefore any woken-up request will have come out of the loop and then
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// exit here. It might or might not have been satisfied.
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--requests_to_wait_;
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exit_cv_.Signal();
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}
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}
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std::vector<Env::IOPriority>
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GenericRateLimiter::GeneratePriorityIterationOrder() {
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std::vector<Env::IOPriority> pri_iteration_order(Env::IO_TOTAL /* 4 */);
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// We make Env::IO_USER a superior priority by always iterating its queue
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// first
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pri_iteration_order[0] = Env::IO_USER;
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bool high_pri_iterated_after_mid_low_pri = rnd_.OneIn(options_.fairness);
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TEST_SYNC_POINT_CALLBACK(
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"GenericRateLimiter::GeneratePriorityIterationOrder::"
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"PostRandomOneInFairnessForHighPri",
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&high_pri_iterated_after_mid_low_pri);
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bool mid_pri_itereated_after_low_pri = rnd_.OneIn(options_.fairness);
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TEST_SYNC_POINT_CALLBACK(
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"GenericRateLimiter::GeneratePriorityIterationOrder::"
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"PostRandomOneInFairnessForMidPri",
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&mid_pri_itereated_after_low_pri);
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if (high_pri_iterated_after_mid_low_pri) {
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pri_iteration_order[3] = Env::IO_HIGH;
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pri_iteration_order[2] =
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mid_pri_itereated_after_low_pri ? Env::IO_MID : Env::IO_LOW;
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pri_iteration_order[1] =
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(pri_iteration_order[2] == Env::IO_MID) ? Env::IO_LOW : Env::IO_MID;
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} else {
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pri_iteration_order[1] = Env::IO_HIGH;
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pri_iteration_order[3] =
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mid_pri_itereated_after_low_pri ? Env::IO_MID : Env::IO_LOW;
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pri_iteration_order[2] =
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(pri_iteration_order[3] == Env::IO_MID) ? Env::IO_LOW : Env::IO_MID;
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}
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TEST_SYNC_POINT_CALLBACK(
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"GenericRateLimiter::GeneratePriorityIterationOrder::"
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"PreReturnPriIterationOrder",
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&pri_iteration_order);
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return pri_iteration_order;
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}
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void GenericRateLimiter::RefillBytesAndGrantRequests() {
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TEST_SYNC_POINT("GenericRateLimiter::RefillBytesAndGrantRequests");
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next_refill_us_ = NowMicrosMonotonic() + options_.refill_period_us;
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// Carry over the left over quota from the last period
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auto refill_bytes_per_period =
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refill_bytes_per_period_.load(std::memory_order_relaxed);
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if (available_bytes_ < refill_bytes_per_period) {
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available_bytes_ += refill_bytes_per_period;
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}
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std::vector<Env::IOPriority> pri_iteration_order =
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GeneratePriorityIterationOrder();
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for (int i = Env::IO_LOW; i < Env::IO_TOTAL; ++i) {
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assert(!pri_iteration_order.empty());
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Env::IOPriority current_pri = pri_iteration_order[i];
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auto* queue = &queue_[current_pri];
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while (!queue->empty()) {
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auto* next_req = queue->front();
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if (available_bytes_ < next_req->request_bytes) {
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// Grant partial request_bytes to avoid starvation of requests
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// that become asking for more bytes than available_bytes_
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// due to dynamically reduced rate limiter's bytes_per_second that
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// leads to reduced refill_bytes_per_period hence available_bytes_
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next_req->request_bytes -= available_bytes_;
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available_bytes_ = 0;
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break;
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}
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available_bytes_ -= next_req->request_bytes;
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next_req->request_bytes = 0;
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total_bytes_through_[current_pri] += next_req->bytes;
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queue->pop_front();
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next_req->granted = true;
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// Quota granted, signal the thread to exit
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next_req->cv.Signal();
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}
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}
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}
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int64_t GenericRateLimiter::CalculateRefillBytesPerPeriod(
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int64_t rate_bytes_per_sec) {
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if (port::kMaxInt64 / rate_bytes_per_sec < options_.refill_period_us) {
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// Avoid unexpected result in the overflow case. The result now is still
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// inaccurate but is a number that is large enough.
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return port::kMaxInt64 / 1000000;
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} else {
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return rate_bytes_per_sec * options_.refill_period_us / 1000000;
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}
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}
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Status GenericRateLimiter::Tune() {
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const int kLowWatermarkPct = 50;
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const int kHighWatermarkPct = 90;
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const int kAdjustFactorPct = 5;
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// computed rate limit will be in
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// `[max_bytes_per_sec_ / kAllowedRangeFactor, max_bytes_per_sec_]`.
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const int kAllowedRangeFactor = 20;
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std::chrono::microseconds prev_tuned_time = tuned_time_;
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tuned_time_ = std::chrono::microseconds(NowMicrosMonotonic());
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int64_t elapsed_intervals =
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(tuned_time_ - prev_tuned_time +
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std::chrono::microseconds(options_.refill_period_us) -
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std::chrono::microseconds(1)) /
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std::chrono::microseconds(options_.refill_period_us);
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// We tune every kRefillsPerTune intervals, so the overflow and division-by-
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// zero conditions should never happen.
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assert(num_drains_ <= port::kMaxInt64 / 100);
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assert(elapsed_intervals > 0);
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int64_t drained_pct = num_drains_ * 100 / elapsed_intervals;
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int64_t prev_bytes_per_sec = GetBytesPerSecond();
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int64_t new_bytes_per_sec;
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if (drained_pct == 0) {
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new_bytes_per_sec = options_.max_bytes_per_sec / kAllowedRangeFactor;
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} else if (drained_pct < kLowWatermarkPct) {
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// sanitize to prevent overflow
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int64_t sanitized_prev_bytes_per_sec =
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std::min(prev_bytes_per_sec, port::kMaxInt64 / 100);
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new_bytes_per_sec =
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std::max(options_.max_bytes_per_sec / kAllowedRangeFactor,
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sanitized_prev_bytes_per_sec * 100 / (100 + kAdjustFactorPct));
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} else if (drained_pct > kHighWatermarkPct) {
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// sanitize to prevent overflow
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int64_t sanitized_prev_bytes_per_sec = std::min(
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prev_bytes_per_sec, port::kMaxInt64 / (100 + kAdjustFactorPct));
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new_bytes_per_sec =
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std::min(options_.max_bytes_per_sec,
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sanitized_prev_bytes_per_sec * (100 + kAdjustFactorPct) / 100);
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} else {
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new_bytes_per_sec = prev_bytes_per_sec;
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}
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if (new_bytes_per_sec != prev_bytes_per_sec) {
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SetBytesPerSecond(new_bytes_per_sec);
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}
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num_drains_ = 0;
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return Status::OK();
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}
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RateLimiter* NewGenericRateLimiter(
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int64_t rate_bytes_per_sec, int64_t refill_period_us /* = 100 * 1000 */,
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int32_t fairness /* = 10 */,
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RateLimiter::Mode mode /* = RateLimiter::Mode::kWritesOnly */,
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bool auto_tuned /* = false */) {
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assert(rate_bytes_per_sec > 0);
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assert(refill_period_us > 0);
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assert(fairness > 0);
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std::unique_ptr<RateLimiter> limiter(
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new GenericRateLimiter(rate_bytes_per_sec, refill_period_us, fairness,
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mode, SystemClock::Default(), auto_tuned));
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Status s = limiter->PrepareOptions(ConfigOptions());
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if (s.ok()) {
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return limiter.release();
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} else {
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assert(false);
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return nullptr;
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}
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}
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namespace {
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#ifndef ROCKSDB_LITE
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static int RegisterBuiltinRateLimiters(ObjectLibrary& library,
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const std::string& /*arg*/) {
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library.AddFactory<RateLimiter>(
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GenericRateLimiter::kClassName(),
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[](const std::string& /*uri*/, std::unique_ptr<RateLimiter>* guard,
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std::string* /*errmsg*/) {
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guard->reset(new GenericRateLimiter(port::kMaxInt64));
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return guard->get();
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});
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size_t num_types;
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return static_cast<int>(library.GetFactoryCount(&num_types));
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}
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static std::unordered_map<std::string, RateLimiter::Mode>
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rate_limiter_mode_map = {
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{"kReadsOnly", RateLimiter::Mode::kReadsOnly},
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{"kWritesOnly", RateLimiter::Mode::kWritesOnly},
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|
{"kAllIo", RateLimiter::Mode::kAllIo},
|
|
};
|
|
#endif // ROCKSDB_LITE
|
|
static bool LoadRateLimiter(const std::string& name,
|
|
std::shared_ptr<RateLimiter>* limiter) {
|
|
auto plen = strlen(GenericRateLimiter::kClassName());
|
|
if (name.size() > plen + 2 && name[plen] == ':' &&
|
|
StartsWith(name, GenericRateLimiter::kClassName())) {
|
|
auto rate = ParseInt64(name.substr(plen + 1));
|
|
limiter->reset(new GenericRateLimiter(rate));
|
|
return true;
|
|
} else {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
static std::unordered_map<std::string, OptionTypeInfo> rate_limiter_type_info =
|
|
{
|
|
#ifndef ROCKSDB_LITE
|
|
{"mode",
|
|
OptionTypeInfo::Enum<RateLimiter::Mode>(0, &rate_limiter_mode_map)},
|
|
#endif // ROCKSDB_LITE
|
|
};
|
|
} // namespace
|
|
|
|
RateLimiter::RateLimiter(Mode mode) : mode_(mode) {
|
|
RegisterOptions("", &mode_, &rate_limiter_type_info);
|
|
}
|
|
|
|
Status RateLimiter::CreateFromString(const ConfigOptions& config_options,
|
|
const std::string& value,
|
|
std::shared_ptr<RateLimiter>* result) {
|
|
if (value.empty()) {
|
|
result->reset();
|
|
return Status::OK();
|
|
} else {
|
|
#ifndef ROCKSDB_LITE
|
|
static std::once_flag once;
|
|
std::call_once(once, [&]() {
|
|
RegisterBuiltinRateLimiters(*(ObjectLibrary::Default().get()), "");
|
|
});
|
|
#endif // ROCKSDB_LITE
|
|
return LoadSharedObject<RateLimiter>(config_options, value, LoadRateLimiter,
|
|
result);
|
|
}
|
|
}
|
|
|
|
} // namespace ROCKSDB_NAMESPACE
|
|
|