63 lines
2.4 KiB
C++
63 lines
2.4 KiB
C++
/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2022-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#pragma once
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#include <maxscale/ccdefs.hh>
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#include <maxbase/stopwatch.hh>
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#include <maxbase/average.hh>
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/** This could arguably be a utility, but is written specifically for rwsplit
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* so it stays here at least for now.
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*/
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namespace maxscale
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{
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/**
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* Query response statistics. Uses median of N samples to filter noise, then
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* uses those medians to calculate the average response time.
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* The class makes an average of the durations between calls to query_started()
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* and query_ended(). Once the stats are good, sync_time_reached(int max) returns true,
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* based on the average containing at least max samples (or medians), or the time
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* sync_duration (constructor arg) has passed since the last reset().
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*/
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class ResponseStat
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{
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public:
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/*
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* @param num_filter_samples - collect num samples, use median
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* @param num_synch_medians - this many medians before the average should be synced, or
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* @param sync_duration - this much time between syncs.
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*/
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ResponseStat(int num_filter_samples = 5,
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int num_synch_medians = 500,
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maxbase::Duration sync_duration = std::chrono::seconds(5));
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void query_started();
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void query_ended();// ok to call without a query_started
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bool make_valid(); // make valid even if there are too few filter_samples
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bool is_valid() const;
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int num_samples() const;
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maxbase::Duration average() const;
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bool sync_time_reached(); // is it time to apply the average?
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void reset();
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private:
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const int m_num_filter_samples;
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const int m_num_synch_medians;
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const maxbase::Duration m_sync_duration;
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int m_sample_count;
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std::vector<maxbase::Duration> m_samples; // N sampels from which median is used
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maxbase::CumulativeAverage m_average;
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maxbase::TimePoint m_last_start;
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maxbase::TimePoint m_next_sync;
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};
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}
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