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102 lines
3.3 KiB
C++
102 lines
3.3 KiB
C++
/**
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* Copyright (c) 2014, Timothy Stack
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or otherlist materials provided with the distribution.
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* * Neither the name of Timothy Stack nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* @file log_accel.hh
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*/
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#ifndef log_accel_h
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#define log_accel_h
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#include <cmath>
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#include <stdint.h>
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#include "base/lnav_log.hh"
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/**
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* Helper class for figuring out changes in the log message rate.
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*/
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class log_accel {
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public:
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/*< The direction of the message rate: steady, accelerating, or decelerating
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*/
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enum direction_t {
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A_STEADY,
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A_DECEL,
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A_ACCEL,
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};
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/**
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* Add a time point that will be used to compute velocity and then
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* acceleration. Points should be added in reverse order, from most
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* recent to oldest.
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*
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* @param point The point in time.
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* @return True if more points can be added.
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*/
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bool add_point(int64_t point);
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/**
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* Get the average acceleration based on the time points we've received.
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*
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* @return The average message acceleration.
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*/
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double get_avg_accel() const;
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/**
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* Compute the message rate direction. If the average acceleration is less
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* than a certain threshold, then we consider the rate to be steady.
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* Otherwise, the message rate is increasing or decreasing.
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*
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* @return The direction of the message rate.
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*/
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direction_t get_direction() const;
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private:
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/**
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* The amount of historical data to include in the average acceleration
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* computation.
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*/
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static const int HISTORY_SIZE = 8;
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/**
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* The minimum range of velocities seen. This value should limit false-
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* positives for small millisecond level fluctuations.
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*/
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static const double MIN_RANGE;
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static const double THRESHOLD;
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int64_t la_last_point{0};
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bool la_last_point_set{false};
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int64_t la_min_velocity{INT64_MAX};
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int64_t la_max_velocity{INT64_MIN};
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int64_t la_velocity[HISTORY_SIZE];
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int la_velocity_size{0};
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};
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#endif
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