Commits on Sep 17, 2022

1. Avoid potentially quadratic runtime when updating selections after mo… …

   …dification
   
   LineRangeSet::add_range() calls Vector::erase() in a loop over the
   same vector. This could cause performance problems when there are many
   selections. Fix this by only calling Vector::erase() once.  I didn't
   measure anything because my benchmark is dominated by another issue
   (see next commit).
   
   LineRangeSet::remove_range() also has a suspicious call to erase()
   but that one is only used in test code, so it doesn't matter.

   

   krobelus committed Sep 17, 2022
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2. Fix quadratic runtime when updating region highlighter matches …

   Running %sYeti<ret>casdf on file
   [example.journal.txt](mawww#4685 (comment))
   can cause noticeable lag.  This is because we insert text at 6000
   selections, which means we need to update highlighters in those lines.
   The runtime for updating range highlighters is quadratic in the
   number of selections: for each selection, we call on_new_range(),
   which calls add_matches(), which calls std::rotate(), which needs
   needs linear time.
   
   Fix the quadratic runtime by calling std::inplace_merge() once instead
   of repeatedly calling std::rotate().  This is works because ranges
   are already sorted.
   
   I used this script to benchmark the improvements.
   (In hindsight I could have just used "-ui json" instead of tmux).
   
   	#!/bin/sh
   	set -ex
   	N=${1:-100}
   	kak=${2:-./kak.opt}
   	for i in $(seq "$N")
   	do
   		echo -n "\
   	2022-02-06 * Earth
   	    expense:electronics:audio    116.7 USD
   	    liability:card              -116.7 USD
   
   	2022-02-06 * Blue Yeti USB Microphone
   	    expense:electronics:audio    116.7 USD
   	    liability:card              -116.7 USD
   
   	"
   	done > big-journal.ledger
   	echo > .empty-tmux.conf 'set -sg escape-time 5'
   	test_tmux() {
   		tmux -S .tmux-socket -f .empty-tmux.conf "$@"
   	}
   	test_tmux new-session -d "$kak" big-journal.ledger
   	test_tmux send-keys '%sYeti' Enter c 1234567890
   	sleep .2
   	test_tmux send-keys Escape
   	while ! test_tmux capture-pane -p | grep 123
   	do
   		sleep .1
   	done
   	test_tmux send-keys ':wq' Enter
   	while test_tmux ls
   	do
   		sleep .1
   	done
   	rm -f .tmux-socket .empty-tmux.conf
   
   This script's runtime used to grow super-linearly but now it grows
   linearly:
   
   	         kak.old  kak.new
   	N=10000    1.142    0.897
   	N=20000    2.879    1.400
   
   Detailed results:
   
   	$ hyperfine -w 1 './bench.sh 10000 ./kak.opt.'{old,new}
   	Benchmark 1: ./bench.sh 10000 ./kak.opt.old
   	  Time (mean ± σ):      1.142 s ±  0.072 s    [User: 0.252 s, System: 0.059 s]
   	  Range (min … max):    1.060 s …  1.242 s    10 runs
   
   	Benchmark 2: ./bench.sh 10000 ./kak.opt.new
   	  Time (mean ± σ):     897.2 ms ±  19.3 ms    [User: 241.6 ms, System: 57.4 ms]
   	  Range (min … max):   853.9 ms … 923.6 ms    10 runs
   
   	Summary
   	  './bench.sh 10000 ./kak.opt.new' ran
   	    1.27 ± 0.09 times faster than './bench.sh 10000 ./kak.opt.old'
   	$ hyperfine -w 1 './bench.sh 20000 ./kak.opt.'{old,new}
   	Benchmark 1: ./bench.sh 20000 ./kak.opt.old
   	  Time (mean ± σ):      2.879 s ±  0.065 s    [User: 0.553 s, System: 0.126 s]
   	  Range (min … max):    2.768 s …  2.963 s    10 runs
   
   	Benchmark 2: ./bench.sh 20000 ./kak.opt.new
   	  Time (mean ± σ):      1.400 s ±  0.018 s    [User: 0.428 s, System: 0.083 s]
   	  Range (min … max):    1.374 s …  1.429 s    10 runs
   
   	Summary
   	  './bench.sh 20000 ./kak.opt.new' ran
   	    2.06 ± 0.05 times faster than '../repro.sh 20000 ./kak.opt.old'

   

   krobelus committed Sep 17, 2022
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