Roland Conybeare
28b6d457c0
git-subtree-dir: xo-reactor git-subtree-mainline:dd1a6b1afcgit-subtree-split:e3a53d10e6
72 lines
2.6 KiB
C++
72 lines
2.6 KiB
C++
/* @file HeapReducer.hpp */
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#pragma once
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#include "Reducer.hpp"
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namespace xo {
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namespace reactor {
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/* collect incoming events in a heap,
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* ordered by timestamp.
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* output events in increasing timestamp order.
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* Information preserving in all other respects
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*
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* Require:
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* - Event is null-constructible
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* - Event is copyable
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* - EventTimeFn :: Event -> utc_nanos
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*/
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template<typename Event, typename EventTimeFn = StructEventTimeFn<Event>>
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class HeapReducer : public ReducerBase<Event, EventTimeFn> {
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public:
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using utc_nanos = xo::time::utc_nanos;
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public:
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HeapReducer() = default;
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HeapReducer(EventTimeFn const & evtfn) : ReducerBase<Event, EventTimeFn>(evtfn) {}
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bool is_empty() const { return this->event_heap_.empty(); }
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/* require: .is_empty() = false */
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utc_nanos next_tm() const { return this->event_tm(this->event_heap_.front()); }
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/* #of events stored in this reducer */
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uint32_t n_event() const { return this->event_heap_.size(); }
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Event const & last_annexed_ev() const { return this->annexed_ev_; }
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void include_event(Event const & ev) {
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this->event_heap_.push_back(ev);
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std::push_heap(this->event_heap_.begin(),
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this->event_heap_.end(),
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std::greater<Event>());
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} /*include_event*/
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void include_event(Event && ev) {
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this->event_heap_.push_back(std::move(ev));
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std::push_heap(this->event_heap_.begin(),
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this->event_heap_.end(),
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std::greater<Event>());
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} /*include_event*/
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Event & annex_one() {
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this->annexed_ev_ = this->event_heap_.front();
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std::pop_heap(this->event_heap_.begin(),
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this->event_heap_.end(),
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std::greater<Event>());
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this->event_heap_.pop_back();
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return this->annexed_ev_;
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} /*annex_one*/
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// ----- Inherited from ReducerBase -----
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// utc_nanos event_tm(Event const & x);
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private:
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/* queued Events, in increasing timestamp order */
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std::vector<Event> event_heap_;
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/* annexed event, removed from .event_heap */
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Event annexed_ev_;
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}; /*HeapReducer*/
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} /*namespace reactor*/
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} /*namespace xo*/
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/* end HeapReducer.hpp */
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