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rocksdb/include/rocksdb/stats_history.h

69 lines
2.5 KiB

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <map>
#include <string>
#include "rocksdb/statistics.h"
#include "rocksdb/status.h"
namespace ROCKSDB_NAMESPACE {
class DBImpl;
// StatsHistoryIterator is the main interface for users to programmatically
// access statistics snapshots that was automatically stored by RocksDB.
// Depending on options, the stats can be in memory or on disk.
// The stats snapshots are indexed by time that they were recorded, and each
// stats snapshot contains individual stat name and value at the time of
// recording.
// Example:
// std::unique_ptr<StatsHistoryIterator> stats_iter;
// Status s = db->GetStatsHistory(0 /* start_time */,
// env->NowMicros() /* end_time*/,
// &stats_iter);
// if (s.ok) {
// for (; stats_iter->Valid(); stats_iter->Next()) {
// uint64_t stats_time = stats_iter->GetStatsTime();
// const std::map<std::string, uint64_t>& stats_map =
// stats_iter->GetStatsMap();
// process(stats_time, stats_map);
// }
// }
class StatsHistoryIterator {
public:
StatsHistoryIterator() {}
virtual ~StatsHistoryIterator() {}
virtual bool Valid() const = 0;
// Moves to the next stats history record. After this call, Valid() is
// true iff the iterator was not positioned at the last entry in the source.
// REQUIRES: Valid()
virtual void Next() = 0;
// Return the time stamp (in seconds) when stats history is recorded.
// REQUIRES: Valid()
virtual uint64_t GetStatsTime() const = 0;
virtual int GetFormatVersion() const { return -1; }
// Return the current stats history as an std::map which specifies the
// mapping from stats name to stats value . The underlying storage
// for the returned map is valid only until the next modification of
// the iterator.
// REQUIRES: Valid()
virtual const std::map<std::string, uint64_t>& GetStatsMap() const = 0;
// If an error has occurred, return it. Else return an ok status.
virtual Status status() const = 0;
};
} // namespace ROCKSDB_NAMESPACE