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
70 lines
2.5 KiB
C++
70 lines
2.5 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 <map>
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#include <string>
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#include "rocksdb/statistics.h"
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#include "rocksdb/status.h"
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namespace rocksdb {
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class DBImpl;
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// StatsHistoryIterator is the main interface for users to programmatically
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// access statistics snapshots that was automatically stored by RocksDB.
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// Depending on options, the stats can be in memory or on disk.
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// The stats snapshots are indexed by time that they were recorded, and each
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// stats snapshot contains individual stat name and value at the time of
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// recording.
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// Example:
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// std::unique_ptr<StatsHistoryIterator> stats_iter;
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// Status s = db->GetStatsHistory(0 /* start_time */,
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// env->NowMicros() /* end_time*/,
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// &stats_iter);
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// if (s.ok) {
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// for (; stats_iter->Valid(); stats_iter->Next()) {
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// uint64_t stats_time = stats_iter->GetStatsTime();
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// const std::map<std::string, uint64_t>& stats_map =
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// stats_iter->GetStatsMap();
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// process(stats_time, stats_map);
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// }
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// }
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class StatsHistoryIterator {
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public:
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StatsHistoryIterator() {}
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virtual ~StatsHistoryIterator() {}
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virtual bool Valid() const = 0;
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// Moves to the next stats history record. After this call, Valid() is
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// true iff the iterator was not positioned at the last entry in the source.
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// REQUIRES: Valid()
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virtual void Next() = 0;
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// Return the time stamp (in seconds) when stats history is recorded.
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// REQUIRES: Valid()
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virtual uint64_t GetStatsTime() const = 0;
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virtual int GetFormatVersion() const { return -1; }
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// Return the current stats history as an std::map which specifies the
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// mapping from stats name to stats value . The underlying storage
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// for the returned map is valid only until the next modification of
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// the iterator.
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// REQUIRES: Valid()
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virtual const std::map<std::string, uint64_t>& GetStatsMap() const = 0;
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// If an error has occurred, return it. Else return an ok status.
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virtual Status status() const = 0;
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};
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} // namespace rocksdb
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