de6ad542c4
This commit refactors slave selection. The compare is still pair-wise but isolated into a small run_comparison() function. The function get_slave_candidate() is used when new connections are created, which I both moved and modified (had to move due to scoping), so diff is off. The slave selection for routing: get_slave_backend() now has the filtering logic from old get_slave_backend() and compare_backends(), the latter of which is removed. Backend functions mostly take shared_ptr<SRWBackend> in various forms (as is, const ref, in a container). Ideally the shared_ptr would be used only to where it is really needed, and either naked ptrs or references to RWBackend would be used. This refactor does not address that issue, but compounds it by using even deeper shared_ptr structures. Fixing that in a future commit.
61 lines
2.4 KiB
C++
61 lines
2.4 KiB
C++
/*
|
|
* Copyright (c) 2016 MariaDB Corporation Ab
|
|
*
|
|
* Use of this software is governed by the Business Source License included
|
|
* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
|
|
*
|
|
* Change Date: 2022-01-01
|
|
*
|
|
* On the date above, in accordance with the Business Source License, use
|
|
* of this software will be governed by version 2 or later of the General
|
|
* Public License.
|
|
*/
|
|
#pragma once
|
|
|
|
#include <maxscale/ccdefs.hh>
|
|
#include <maxbase/stopwatch.hh>
|
|
#include <maxbase/average.hh>
|
|
|
|
/** This could arguably be a utility, but is written specifically for rwsplit
|
|
* so it stays here at least for now.
|
|
*/
|
|
namespace maxscale
|
|
{
|
|
/**
|
|
* Query response statistics. Uses median of N samples to filter noise, then
|
|
* uses those medians to calculate the average response time.
|
|
* The class makes an average of the durations between calls to query_started()
|
|
* and query_ended(). Once the stats are good, sync_time_reached(int max) returns true,
|
|
* based on the average containing at least max samples (or medians), or the time
|
|
* sync_duration (constructor arg) has passed since the last reset().
|
|
*/
|
|
class ResponseStat
|
|
{
|
|
public:
|
|
/* @param ignore_first_n - the first few queries tend to have more overhead
|
|
* @param n_filter_samples - collect num samples, use median
|
|
* @param num_synch_samples - this many medians before the average should be synced, or
|
|
* @param sync_duration - this much time between syncs.
|
|
*/
|
|
ResponseStat(int ignore_first_n = 5,
|
|
int num_filter_samples = 3,
|
|
maxbase::Duration sync_duration = std::chrono::seconds(5));
|
|
void query_started();
|
|
void query_ended();// ok to call without a query_started
|
|
bool is_valid() const;
|
|
int num_samples() const;
|
|
maxbase::Duration average() const;
|
|
bool sync_time_reached(int num_synch_medians); // is it time to apply the average?
|
|
void reset();
|
|
private:
|
|
int m_ignore_first_n;
|
|
const int m_num_filter_samples;
|
|
const maxbase::Duration m_sync_duration;
|
|
int m_sample_count;
|
|
std::vector<maxbase::Duration> m_samples; // N sampels from which median is used
|
|
maxbase::CumulativeAverage m_average;
|
|
maxbase::TimePoint m_last_start;
|
|
maxbase::TimePoint m_next_sync;
|
|
};
|
|
}
|