415c7fa2d7
Fix comments. Fix a bug in make_valid(). Change sync time (when the average should be pushed to the server EMA) to only depend on time, not use sample_max. This decreases the amount of sync calls, and allows for a much shorter sync time. Testing shows this to be more stabel and allows to make sample_max adaptive .
54 lines
1.8 KiB
C++
54 lines
1.8 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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namespace maxscale
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{
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/**
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* Query response time average for a backend. Uses median of N samples to filter noise,
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* then uses those medians to calculate the average response time.
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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 (digital filter)
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* @param sync_duration - this much time between synchronize to server stats.
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*/
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ResponseStat(int num_filter_samples = 9,
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maxbase::Duration sync_duration = std::chrono::milliseconds(250));
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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 only 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 to the server?
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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 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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