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/**
* Copyright (C) 2016 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects
* for all of the code used other than as permitted herein. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you do not
* wish to do so, delete this exception statement from your version. If you
* delete this exception statement from all source files in the program,
* then also delete it in the license file.
*/
#pragma once
#include <array>
#include "mongo/db/commands.h"
namespace mongo {
class BSONObjBuilder;
/**
* Stores statistics for latencies of read, write, and command operations.
*
* Note: This class is not thread-safe.
*/
class OperationLatencyHistogram {
public:
static const int kMaxBuckets = 51;
// Inclusive lower bounds of the histogram buckets.
static const std::array<uint64_t, kMaxBuckets> kLowerBounds;
/**
* Increments the bucket of the histogram based on the operation type.
*/
void increment(uint64_t latency, Command::ReadWriteType type);
/**
* Appends the three histograms with latency totals and operation counts.
*/
void append(bool includeHistograms, BSONObjBuilder* builder) const;
private:
struct HistogramData {
std::array<uint64_t, kMaxBuckets> buckets{};
uint64_t entryCount = 0;
uint64_t sum = 0;
};
static int _getBucket(uint64_t latency);
static uint64_t _getBucketMicros(int bucket);
void _append(const HistogramData& data,
const char* key,
bool includeHistograms,
BSONObjBuilder* builder) const;
void _incrementData(uint64_t latency, int bucket, HistogramData* data);
HistogramData _reads, _writes, _commands;
};
} // namespace mongo
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