revset: use changelog's `headrevs` method to compute heads Instead of implementing our own algorithm, we reuse a more generic one. This previous algorithm did not leave much room for laziness so we do not really regress in that regards. A small impact is visible for first/last value in some of the simpler cases. The time needed to compute all values improves overall. Small optimization in the dagop.headrevs function will help to buy this back in the next changesets. There is room to introduce actual laziness in this algorithm, but this is out of scope for this series. This has no visible effect on expensive cases: revset: heads(matching(tip, "author")) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 7.574666 7.545950 7.570743 7.578697 7.525725 7.509929 7.443854 7.488442 7.452880 7.445411 7.689107 1) 7.549390 7.389162 7.529790 7.536297 7.450467 7.555347 7.404586 7.514948 7.542794 7.524787 7.536918 revset: heads(matching(tip, "author")) and -10000:-1 plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 7.512533 7.605877 7.382894 7.462109 7.420086 7.575034 7.448452 7.549374 7.457880 7.450308 7.515019 1) 7.548677 7.551832 7.629598 7.494857 7.550554 7.521838 7.451794 error 7.321781 7.546885 7.557523 revset: (-10000:-1) and heads(matching(tip, "author")) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 7.465419 7.570089 7.439594 7.521221 7.498716 7.492922 7.479108 7.552397 7.407888 error 7.468264 1) 7.539866 7.548045 7.491761 7.517170 7.469824 7.501990 7.579102 7.502568 7.578102 7.555754 7.567622 In simpler cases, we see a 10-15% impact when retrieving a single value, the full computation time is equivalent or improved: revset: (-5000:-1000) and heads(-10000:-1) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 0.004244 0.003368 0.003313 0.003367 0.003327 0.004325 0.003401 0.003379 0.004310 0.003359 0.003396 1) 0.003969 93% 0.003862 114% 0.003834 115% 0.003810 113% 0.003822 114% 0.003940 91% 0.003908 114% 0.003814 112% 0.003986 92% 0.003954 117% 0.003816 112% revset: heads(all()) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 0.036503 0.032564 0.030024 0.032378 0.030887 0.036367 0.031713 0.032205 0.036467 0.032286 0.030300 1) 0.036668 0.035347 108% 0.035611 118% 0.035358 109% 0.035726 115% 0.036411 0.035261 111% 0.036096 112% 0.036052 0.035095 108% 0.035792 118% revset: heads(-10000:-1) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 0.003936 0.003218 0.003227 0.003302 0.003328 0.003848 0.003305 0.003252 0.003839 0.003306 0.003279 1) 0.003870 0.003785 117% 0.003821 118% 0.003780 114% 0.003769 113% 0.003776 0.003792 114% 0.003805 117% 0.003810 0.003798 114% 0.003840 117%

revlog: accept a revs argument in `headrevs` Computing the heads of an arbitrary set of revision is useful, we make it possible to do so through the `headrevs` method of the revlog. Right now, this is just calling dagop's implementation. However, we expect to plug a native implementation soon.

revset: inline parents computation to reuse the input argument Before this change, using `heads(xxx)` would compute `xxx` multiple time. Once to select the possible candidates, and once to compute the parent set. The code used to compute parents is a direct copy past from the `parents` revset. We expect to replace it quickly in a later changeset. So we did not bother with extracting a function. In case where the input set is expensive to compute this provides a significant performance boost. (output are from contrib/revsetbenchmarks.py) revset: heads(matching(tip, "author")) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 15.06746 14.92766 7.335694 15.03092 7.635580 15.04133 7.454806 15.27565 14.97796 14.87607 7.480900 1) 7.529300 49% 7.592152 50% 7.480548 7.544528 50% 7.421248 7.522279 50% 7.484876 7.613154 49% 7.599553 50% 7.561410 50% 7.508990 In other cases, with a faster input set, we still see a (smaller) performance boost. revset: heads(all()) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 0.038994 0.035981 0.033345 0.035751 0.033569 0.039833 0.033653 0.035428 0.039483 0.035750 0.033657 1) 0.036359 93% 0.032613 90% 0.031479 94% 0.032790 91% 0.030681 91% 0.036456 91% 0.031128 92% 0.032461 91% 0.036276 91% 0.032721 91% 0.031024 92% revset: heads(-10000:-1) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 0.004184 0.003576 0.003593 0.003628 0.003569 0.004277 0.003590 0.003719 0.004194 0.003659 0.003690 1) 0.003850 92% 0.003267 91% 0.003256 90% 0.003261 89% 0.003204 89% 0.003855 90% 0.003294 91% 0.003164 85% 0.003848 91% 0.003302 90% 0.003296 89% revset: (-5000:-1000) and heads(-10000:-1) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 0.004730 0.003429 0.003359 0.003391 0.003369 0.004787 0.003418 0.003469 0.004772 0.003445 0.003454 1) 0.004277 90% 0.003430 0.003423 0.003353 0.003340 0.004250 88% 0.003387 0.003385 0.004325 90% 0.003413 0.003373 revset: heads(matching(tip, "author")) and -10000:-1 plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 8.250275 8.231453 7.508579 8.230028 7.529777 8.358590 7.531636 8.301830 8.137196 8.421402 7.540355 1) 7.474707 90% 7.587345 92% 7.486192 7.548340 91% 7.485288 7.659108 91% 7.485307 7.628890 91% 7.523479 92% 7.558384 89% 7.467524 revset: (-10000:-1) and heads(matching(tip, "author")) plain min max first last reverse rev..rst rev..ast sort sor..rst sor..ast 0) 8.341504 8.315248 7.489414 8.320746 7.548816 8.244137 7.514663 8.281701 8.218862 8.412644 7.456793 1) 7.553704 90% 7.570679 91% 7.391438 7.724237 92% 7.527400 7.570637 91% 7.580622 7.450912 89% 7.556154 91% 7.514726 89% 7.494328

revsetbenchmarks: add various examples around the 'heads()' revset We are about to work on the performance of this revset. Before doing so we defines various ways to use it.

revsetbenchmarks: support revset starting with a "-" Before this change, there was no strict separation between arguments and the benchmarked revset. This is easy to fix.

py3: two more passing tests from the ratchet Differential Revision: https://phab.mercurial-scm.org/D5627

py3: test*gendoc*.t passes on Python 3 The buildbot didn't notice because docutils isn't installed in Python 3 there yet. I verified this locally. Differential Revision: https://phab.mercurial-scm.org/D5617