d394a6bb48
Summary: This diff adds a new ticker stat, NUMBER_ITER_SKIP, to count the number of internal keys skipped during iteration. Keys can be skipped due to deletes, or lower sequence number, or higher sequence number than the one requested. Also, fix the issue when StatisticsData is naturally aligned on cacheline boundary, padding becomes a zero size array, which the Windows compiler doesn't like. So add a cacheline worth of padding in that case to keep it happy. We cannot conditionally add padding as gcc doesn't allow using sizeof in preprocessor directives. Closes https://github.com/facebook/rocksdb/pull/3177 Differential Revision: D6353897 Pulled By: anand1976 fbshipit-source-id: 441d5a09af9c4e22e7355242dfc0c7b27aa0a6c2
115 lines
3.8 KiB
C++
115 lines
3.8 KiB
C++
// 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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#pragma once
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#include "rocksdb/statistics.h"
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#include <vector>
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#include <atomic>
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#include <string>
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#include "monitoring/histogram.h"
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#include "port/likely.h"
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#include "port/port.h"
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#include "util/core_local.h"
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#include "util/mutexlock.h"
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#ifdef __clang__
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#define ROCKSDB_FIELD_UNUSED __attribute__((__unused__))
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#else
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#define ROCKSDB_FIELD_UNUSED
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#endif // __clang__
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namespace rocksdb {
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enum TickersInternal : uint32_t {
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INTERNAL_TICKER_ENUM_START = TICKER_ENUM_MAX,
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INTERNAL_TICKER_ENUM_MAX
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};
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enum HistogramsInternal : uint32_t {
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INTERNAL_HISTOGRAM_START = HISTOGRAM_ENUM_MAX,
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INTERNAL_HISTOGRAM_ENUM_MAX
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};
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class StatisticsImpl : public Statistics {
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public:
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StatisticsImpl(std::shared_ptr<Statistics> stats,
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bool enable_internal_stats);
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virtual ~StatisticsImpl();
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virtual uint64_t getTickerCount(uint32_t ticker_type) const override;
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virtual void histogramData(uint32_t histogram_type,
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HistogramData* const data) const override;
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std::string getHistogramString(uint32_t histogram_type) const override;
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virtual void setTickerCount(uint32_t ticker_type, uint64_t count) override;
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virtual uint64_t getAndResetTickerCount(uint32_t ticker_type) override;
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virtual void recordTick(uint32_t ticker_type, uint64_t count) override;
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virtual void measureTime(uint32_t histogram_type, uint64_t value) override;
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virtual Status Reset() override;
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virtual std::string ToString() const override;
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virtual bool HistEnabledForType(uint32_t type) const override;
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private:
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// If non-nullptr, forwards updates to the object pointed to by `stats_`.
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std::shared_ptr<Statistics> stats_;
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// TODO(ajkr): clean this up since there are no internal stats anymore
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bool enable_internal_stats_;
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// Synchronizes anything that operates across other cores' local data,
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// such that operations like Reset() can be performed atomically.
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mutable port::Mutex aggregate_lock_;
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// The ticker/histogram data are stored in this structure, which we will store
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// per-core. It is cache-aligned, so tickers/histograms belonging to different
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// cores can never share the same cache line.
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//
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// Alignment attributes expand to nothing depending on the platform
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struct StatisticsData {
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std::atomic_uint_fast64_t tickers_[INTERNAL_TICKER_ENUM_MAX] = {{0}};
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HistogramImpl histograms_[INTERNAL_HISTOGRAM_ENUM_MAX];
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char
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padding[(CACHE_LINE_SIZE -
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(INTERNAL_TICKER_ENUM_MAX * sizeof(std::atomic_uint_fast64_t) +
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INTERNAL_HISTOGRAM_ENUM_MAX * sizeof(HistogramImpl)) %
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CACHE_LINE_SIZE)] ROCKSDB_FIELD_UNUSED;
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};
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static_assert(sizeof(StatisticsData) % 64 == 0, "Expected 64-byte aligned");
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CoreLocalArray<StatisticsData> per_core_stats_;
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uint64_t getTickerCountLocked(uint32_t ticker_type) const;
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std::unique_ptr<HistogramImpl> getHistogramImplLocked(
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uint32_t histogram_type) const;
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void setTickerCountLocked(uint32_t ticker_type, uint64_t count);
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};
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// Utility functions
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inline void MeasureTime(Statistics* statistics, uint32_t histogram_type,
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uint64_t value) {
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if (statistics) {
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statistics->measureTime(histogram_type, value);
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}
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}
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inline void RecordTick(Statistics* statistics, uint32_t ticker_type,
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uint64_t count = 1) {
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if (statistics) {
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statistics->recordTick(ticker_type, count);
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}
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}
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inline void SetTickerCount(Statistics* statistics, uint32_t ticker_type,
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uint64_t count) {
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if (statistics) {
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statistics->setTickerCount(ticker_type, count);
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}
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}
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}
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