MXS-1777 Create new utility library
The purpose of this library is to create a utility library that is not dependent on maxscale for use in both maxscale and system test, and possibly other apps. As time permits general purpose utilities from maxscale-common can be moved to the new library. Here are answers to questions you may have: - A top level directory "maxutils" contains the libraries. The current structure is simply maxutils/maxbase. Each library has an 'include' and a 'scr' directory where public headers exist in 'include' - Code is in a namespace with the same name as the directory. - Headers are included like this: `#include <maxbase/stopwatch.hh>` - In case the library is published on its own, the include directives stay the same (headers would be in /usr/include/maxutil, for example). - I am not advocating many small libraries. But if some larger library is written, say a general purpose statemachine, it would not pollute util/maxutil but go to util/maxsm. Another example: Worker. It is a larger concept, but used so widely in code that it could very well live in maxutil. NOTE: this was previously Review Request #6245.
This commit is contained in:
Niclas Antti
290
maxutils/maxbase/src/eventcount.cc
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290
maxutils/maxbase/src/eventcount.cc
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/*
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* Copyright (c) 2018 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: 2020-01-01
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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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#include <maxbase/eventcount.hh>
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#include <algorithm>
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#include <iostream>
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#include <iomanip>
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#include <sstream>
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#include <map>
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namespace maxbase
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{
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EventCount::EventCount(const std::string& event_id, Duration time_window, Duration granularity) :
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m_event_id(event_id),
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m_time_window(time_window),
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m_granularity(granularity.count())
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{
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increment();
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}
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void EventCount::increment()
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{
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using namespace std::chrono;
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auto ticks = time_point_cast<nanoseconds>(Clock::now()).time_since_epoch().count();
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if (m_granularity)
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{
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ticks = ticks / m_granularity * m_granularity;
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}
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if (m_timestamps.empty()
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|| m_timestamps.back().time_point.time_since_epoch().count() != ticks)
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{
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m_timestamps.emplace_back(TimePoint(ticks), 1);
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}
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else
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{
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++m_timestamps.back().count;
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}
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}
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namespace
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{
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struct TimePointLessEqual
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{
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TimePoint lhs;
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TimePointLessEqual(TimePoint tp) : lhs(tp) {}
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bool operator()(const EventCount::Timestamp& rhs) const
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{
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return lhs <= rhs.time_point;
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}
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bool operator()(TimePoint rhs) const
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{
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return lhs <= rhs;
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}
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};
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}
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void EventCount::purge() const
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{
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StopWatch sw;
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auto windowBegin = Clock::now() - m_time_window;
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auto ite = std::find_if(m_timestamps.begin(), m_timestamps.end(),
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TimePointLessEqual(windowBegin));
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m_timestamps.erase(m_timestamps.begin(), ite);
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}
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int EventCount::count() const
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{
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purge();
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int count {0};
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for (auto ite = m_timestamps.begin(); ite != m_timestamps.end(); ++ite)
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{
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count += ite->count;
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}
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return count;
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}
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void EventCount::dump(std::ostream &os) const
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{
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os << m_event_id << ": " << count() << " " << m_timestamps.size();
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}
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std::ostream& operator<<(std::ostream& os, const EventCount& EventCount)
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{
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EventCount.dump(os);
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return os;
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}
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// Force a purge once in awhile, could be configurable. This is needed if
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// a client generates lots of events but rarely reads them back (purges).
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const int CleanupCountdown = 10000;
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SessionCount::SessionCount(const std::string& sess_id, Duration time_window,
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Duration granularity) :
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m_sess_id(sess_id), m_time_window(time_window), m_granularity(granularity),
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m_cleanup_countdown(CleanupCountdown)
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{
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}
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const std::vector<EventCount> &SessionCount::event_counts() const
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{
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purge();
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return m_event_counts;
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}
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bool SessionCount::empty() const
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{
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purge();
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return m_event_counts.empty();
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}
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namespace
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{
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struct MatchEventId
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{
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std::string event_id;
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MatchEventId(const std::string& id) : event_id(id) {};
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bool operator()(const EventCount& stats) const
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{
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return event_id == stats.event_id();
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}
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};
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}
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void SessionCount::increment(const std::string& event_id)
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{
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// Always put the incremented entry (latest timestamp) last in the vector (using
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// rotate). This means the vector is ordered so that expired entries are always first.
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// Find in reverse, the entry is more likely to be towards the end. Actually no,
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// for some reason the normal search is slightly faster when measured.
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auto ite = find_if(m_event_counts.begin(), m_event_counts.end(),
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MatchEventId(event_id));
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if (ite == m_event_counts.end())
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{
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m_event_counts.emplace_back(event_id, m_time_window, m_granularity);
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}
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else
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{
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ite->increment();
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// rotate so that the entry becomes the last one
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auto next = std::next(ite);
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std::rotate(ite, next, m_event_counts.end());
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}
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if (!--m_cleanup_countdown)
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{
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purge();
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}
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}
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namespace
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{
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struct NonZeroEntry
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{
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bool operator()(const EventCount& stats)
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{
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return stats.count() != 0;
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}
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};
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}
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void SessionCount::purge() const
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{
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StopWatch sw;
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m_cleanup_countdown = CleanupCountdown;
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// erase entries up to the first non-zero one
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auto ite = find_if(m_event_counts.begin(), m_event_counts.end(), NonZeroEntry());
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// The gcc 4.4 vector::erase bug only happens if iterators are the same.
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if (ite != m_event_counts.begin())
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{
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m_event_counts.erase(m_event_counts.begin(), ite);
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}
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}
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void SessionCount::dump(std::ostream& os) const
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{
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purge();
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if (!m_event_counts.empty())
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{
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os << " Session: " << m_sess_id << '\n';
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for (auto ite = m_event_counts.begin(); ite != m_event_counts.end(); ++ite)
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{
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os << " " << *ite << '\n';
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}
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}
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}
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void dumpHeader(std::ostream& os, const SessionCount& stats, const std::string& type)
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{
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TimePoint tp = Clock::now();
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os << type << ": Time:" << tp
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<< " Time Window: " << stats.time_window() << '\n';
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}
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void dump(std::ostream& os, const std::vector<SessionCount>& sessions)
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{
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if (sessions.empty())
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{
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return;
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}
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dumpHeader(os, sessions[0], "Count");
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for (auto session = sessions.begin(); session != sessions.end(); ++session)
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{
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session->dump(os);
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}
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}
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void dumpTotals(std::ostream& os, const std::vector<SessionCount> &sessions)
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{
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if (sessions.empty())
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{
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return;
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}
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std::map<std::string, int> counts;
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for (auto session = sessions.begin(); session != sessions.end(); ++session)
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{
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const auto& events = session->event_counts();
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for (auto event = events.begin(); event != events.end(); ++event)
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{
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counts[event->event_id()] += event->count();
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}
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}
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if (!counts.empty())
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{
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dumpHeader(os, sessions[0], "Count Totals");
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for (auto ite = counts.begin(); ite != counts.end(); ++ite)
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{
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os << " " << ite->first << ": " << ite->second << '\n';
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}
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}
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}
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// EXTRA
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// This section needed for gcc 4.4, to use move semantics and variadics.
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EventCount::EventCount(EventCount && ss) :
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m_event_id(std::move(ss.m_event_id)),
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m_time_window(std::move(ss.m_time_window)),
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m_granularity(std::move(ss.m_granularity)),
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m_timestamps(std::move(ss.m_timestamps))
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{
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}
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EventCount &EventCount::operator=(EventCount && ss)
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{
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m_event_id = std::move(ss.m_event_id);
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m_time_window = std::move(ss.m_time_window);
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m_granularity = std::move(ss.m_granularity);
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m_timestamps = std::move(ss.m_timestamps);
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return *this;
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}
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SessionCount::SessionCount(SessionCount&& ss) :
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m_sess_id(std::move(ss.m_sess_id)),
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m_time_window(std::move(ss.m_time_window)),
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m_granularity(std::move(ss.m_granularity)),
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m_cleanup_countdown(std::move(ss.m_cleanup_countdown)),
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m_event_counts(std::move(ss.m_event_counts))
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{
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}
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SessionCount & SessionCount::operator=(SessionCount&& ss)
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{
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m_sess_id = std::move(ss.m_sess_id);
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m_time_window = std::move(ss.m_time_window);
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m_granularity = std::move(ss.m_granularity);
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m_cleanup_countdown = std::move(ss.m_cleanup_countdown);
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m_event_counts = std::move(ss.m_event_counts);
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return *this;
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}
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} // maxbase
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