671d15cbdd
Summary: This PR continues the work in https://github.com/facebook/rocksdb/pull/4748 and https://github.com/facebook/rocksdb/pull/4535 by adding a new DBOption `persist_stats_to_disk` which instructs RocksDB to persist stats history to RocksDB itself. When statistics is enabled, and both options `stats_persist_period_sec` and `persist_stats_to_disk` are set, RocksDB will periodically write stats to a built-in column family in the following form: key -> (timestamp in microseconds)#(stats name), value -> stats value. The existing API `GetStatsHistory` will detect the current value of `persist_stats_to_disk` and either read from in-memory data structure or from the hidden column family on disk. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5046 Differential Revision: D15863138 Pulled By: miasantreble fbshipit-source-id: bb82abdb3f2ca581aa42531734ac799f113e931b
75 lines
2.9 KiB
C++
75 lines
2.9 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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// 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 "rocksdb/stats_history.h"
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namespace rocksdb {
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// InMemoryStatsHistoryIterator can be used to access stats history that was
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// stored by an in-memory two level std::map(DBImpl::stats_history_). It keeps
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// a copy of the stats snapshot (in stats_map_) that is currently being pointed
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// to, which allows the iterator to access the stats snapshot even when
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// the background garbage collecting thread purges it from the source of truth
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// (`DBImpl::stats_history_`). In that case, the iterator will continue to be
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// valid until a call to `Next()` returns no result and invalidates it. In
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// some extreme cases, the iterator may also return fragmented segments of
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// stats snapshots due to long gaps between `Next()` calls and interleaved
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// garbage collection.
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class InMemoryStatsHistoryIterator final : public StatsHistoryIterator {
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public:
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// Setup InMemoryStatsHistoryIterator to return stats snapshots between
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// seconds timestamps [start_time, end_time)
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InMemoryStatsHistoryIterator(uint64_t start_time, uint64_t end_time,
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DBImpl* db_impl)
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: start_time_(start_time),
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end_time_(end_time),
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valid_(true),
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db_impl_(db_impl) {
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AdvanceIteratorByTime(start_time_, end_time_);
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}
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~InMemoryStatsHistoryIterator() override;
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bool Valid() const override;
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Status status() const override;
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// Move to the next stats snapshot currently available
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// This function may invalidate the iterator
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// REQUIRES: Valid()
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void Next() override;
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// REQUIRES: Valid()
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uint64_t GetStatsTime() const override;
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// This function is idempotent
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// REQUIRES: Valid()
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const std::map<std::string, uint64_t>& GetStatsMap() const override;
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private:
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// advance the iterator to the next stats history record with timestamp
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// between [start_time, end_time)
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void AdvanceIteratorByTime(uint64_t start_time, uint64_t end_time);
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// No copying allowed
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InMemoryStatsHistoryIterator(const InMemoryStatsHistoryIterator&) = delete;
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void operator=(const InMemoryStatsHistoryIterator&) = delete;
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InMemoryStatsHistoryIterator(InMemoryStatsHistoryIterator&&) = delete;
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InMemoryStatsHistoryIterator& operator=(InMemoryStatsHistoryIterator&&) =
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delete;
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uint64_t time_;
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uint64_t start_time_;
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uint64_t end_time_;
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std::map<std::string, uint64_t> stats_map_;
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Status status_;
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bool valid_;
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DBImpl* db_impl_;
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};
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} // namespace rocksdb
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