Mercurial > public > mercurial-scm > hg
comparison mercurial/revlogutils/deltas.py @ 39336:1c6ff52fe9cf
revlogdeltas: split candidate groups selection from the filtering logic
The group iteration has two main components:
* walking candidates, the logic that we are about to extend to build
intermediate snapshots,
* Making sure we test diffs against interesting bases. No duplicated tests,
skipping empty revisions, etc.
We split `_candidategroups` to separate the two components. This achieves two
goals:
* It will be simpler to update the walking logic for intermediate snapshots,
* We can gather the filtering logic from `finddeltainfo` into
`_candidategroups` to centralize it.
| author | Boris Feld <boris.feld@octobus.net> |
|---|---|
| date | Wed, 29 Aug 2018 09:55:11 -0700 |
| parents | 1441eb38849f |
| children | 37957e07138c |
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| 39335:1441eb38849f | 39336:1c6ff52fe9cf |
|---|---|
| 567 return False | 567 return False |
| 568 | 568 |
| 569 return True | 569 return True |
| 570 | 570 |
| 571 def _candidategroups(revlog, p1, p2, cachedelta): | 571 def _candidategroups(revlog, p1, p2, cachedelta): |
| 572 """Provides group of revision to be tested as delta base | |
| 573 | |
| 574 This top level function focus on emitting groups with unique and worthwhile | |
| 575 content. See _raw_candidate_groups for details about the group order. | |
| 572 """ | 576 """ |
| 573 Provides revisions that present an interest to be diffed against, | 577 # should we try to build a delta? |
| 574 grouped by level of easiness. | 578 if not (len(revlog) and revlog._storedeltachains): |
| 579 return | |
| 580 | |
| 581 tested = set([nullrev]) | |
| 582 for group in _rawgroups(revlog, p1, p2, cachedelta): | |
| 583 group = tuple(r for r in group if r not in tested) | |
| 584 tested.update(group) | |
| 585 if group: | |
| 586 yield group | |
| 587 | |
| 588 def _rawgroups(revlog, p1, p2, cachedelta): | |
| 589 """Provides group of revision to be tested as delta base | |
| 590 | |
| 591 This lower level function focus on emitting delta theorically interresting | |
| 592 without looking it any practical details. | |
| 593 | |
| 594 The group order aims at providing fast or small candidates first. | |
| 575 """ | 595 """ |
| 576 gdelta = revlog._generaldelta | 596 gdelta = revlog._generaldelta |
| 577 curr = len(revlog) | 597 curr = len(revlog) |
| 578 prev = curr - 1 | 598 prev = curr - 1 |
| 579 | 599 |
| 588 # Assume what we received from the server is a good choice | 608 # Assume what we received from the server is a good choice |
| 589 # build delta will reuse the cache | 609 # build delta will reuse the cache |
| 590 yield (cachedelta[0],) | 610 yield (cachedelta[0],) |
| 591 tested.add(cachedelta[0]) | 611 tested.add(cachedelta[0]) |
| 592 | 612 |
| 593 if gdelta: | 613 # This condition is true most of the time when processing |
| 594 # exclude already lazy tested base if any | 614 # changegroup data into a generaldelta repo. The only time it |
| 595 parents = [p for p in (p1, p2) | 615 # isn't true is if this is the first revision in a delta chain |
| 596 if p != nullrev and p not in tested] | 616 # or if ``format.generaldelta=true`` disabled ``lazydeltabase``. |
| 597 | 617 if cachedelta and gdelta and revlog._lazydeltabase: |
| 598 if not revlog._deltabothparents and len(parents) == 2: | 618 # Assume what we received from the server is a good choice |
| 599 parents.sort() | 619 # build delta will reuse the cache |
| 600 # To minimize the chance of having to build a fulltext, | 620 yield (cachedelta[0],) |
| 601 # pick first whichever parent is closest to us (max rev) | 621 |
| 602 yield (parents[1],) | 622 if gdelta: |
| 603 # then the other one (min rev) if the first did not fit | 623 # exclude already lazy tested base if any |
| 604 yield (parents[0],) | 624 parents = [p for p in (p1, p2) if p != nullrev] |
| 605 tested.update(parents) | 625 |
| 606 elif len(parents) > 0: | 626 if not revlog._deltabothparents and len(parents) == 2: |
| 607 # Test all parents (1 or 2), and keep the best candidate | 627 parents.sort() |
| 608 yield parents | 628 # To minimize the chance of having to build a fulltext, |
| 609 tested.update(parents) | 629 # pick first whichever parent is closest to us (max rev) |
| 610 | 630 yield (parents[1],) |
| 611 if prev not in tested: | 631 # then the other one (min rev) if the first did not fit |
| 612 # other approach failed try against prev to hopefully save us a | 632 yield (parents[0],) |
| 613 # fulltext. | 633 elif len(parents) > 0: |
| 614 yield (prev,) | 634 # Test all parents (1 or 2), and keep the best candidate |
| 615 tested.add(prev) | 635 yield parents |
| 636 | |
| 637 # other approach failed try against prev to hopefully save us a | |
| 638 # fulltext. | |
| 639 yield (prev,) | |
| 616 | 640 |
| 617 class deltacomputer(object): | 641 class deltacomputer(object): |
| 618 def __init__(self, revlog): | 642 def __init__(self, revlog): |
| 619 self.revlog = revlog | 643 self.revlog = revlog |
| 620 | 644 |