revlog: make isdescendantrev(a, b) check if a < b This check was taken from rebase.py. It seems to make sense to move it here, but I haven't done any measurements. Differential Revision: https://phab.mercurial-scm.org/D3930

revlog: replace descendant(b, a) by isdescendantrev(a, b) (API) The "is" is to match "isancestor" and to make it clear that it doesn't return a descendant. The "rev" is to make it clear that it's not about nodeids (unlike e.g. isancestor()). The argument order change is just seems more natural (and makes isancestor() less confusing). Differential Revision: https://phab.mercurial-scm.org/D3929

revlog: move comment about commonancestorsheads where it's used Differential Revision: https://phab.mercurial-scm.org/D3928

removeemptydirs: add test for `hg split` inside a disappearing directory Differential Revision: https://phab.mercurial-scm.org/D3927

fncache: avoid loading the filename cache when not actually modifying it With time, fncache can become very large. The mozilla-central repo for example, has a 31M and growing fncache file. Loading this file takes time (280ms for the mozilla-central repository). In many scenarios, we don't need to load fncache at all. For example, when committing changes to existing files, or pushing such commits to another clone. This patch detects when a name is added via store.vfs(), and only loads the cache if a) the data metadata file doesn't already exist, or b) when opening for appending, the data or metadata file exists but has size (a transaction rollback leaves behind such files). Benchmarks (run on Macos 10.13 on a 2017-model Macbook Pro with Core i7 2.9GHz and flash drive), each test without and with patch run 5 times: * committing to an existing file, against the mozilla-central repository. Baseline real time average 2.3736, with patch 1.9884. * unbundling a large changeset consisting *only* of existing-file modifications (159 revisions, 1050 modifications, mozilla-central 4a250a0e4f29:beea9ac7d823), into a clone limited to the ancestor revision of that revset). Baseline real time average 1.5048, with patch 1.3108.

tests: add diff color trailing whitespace test

scmutil: fix shortesthexnodeidprefix on Python 3 for 0-prefixed nodes This fixes test-bookmarks.t on Python 3 (which had regressed.) Differential Revision: https://phab.mercurial-scm.org/D3926

tests: add missing b prefix in test-context.py # skip-blame just a b prefix Differential Revision: https://phab.mercurial-scm.org/D3925

manifest: just duplicate the definition of items as iteritems The forwarding trick was failing test-check-interfaces on Python 3. Duplicating a line of code is easy enough I'm doing that rather than try and figure out what's going on in any kind of detail. Differential Revision: https://phab.mercurial-scm.org/D3924

tests: properly sort imports in test-nointerrupt.t Somehow this was only detected in Python 3. Differential Revision: https://phab.mercurial-scm.org/D3923

revlog: adjust doctest examples to be portable to Python 3 The range() builtin returns a special object rather than a list, but we really wanted a list in these examples. Differential Revision: https://phab.mercurial-scm.org/D3922

py3: whitelist 3 more passing tests caught with the ratchet Differential Revision: https://phab.mercurial-scm.org/D3921

grep: hide cryptic revision number by default I believe nobody would want to see the "2147483647:" prefix while grepping working directory files. The wdir revision is still visible if "-r wdir()" is specified since a revset may point to more than one revisions, and it seems confusing to change the visibility dynamically by the number of the matched revisions. Differential Revision: https://phab.mercurial-scm.org/D3920

grep: restore pre-9ef10437bb88 behavior, enable wdir search by tweakdefaults Unfortunately, python-hglib relies on the original grep behavior and is documented as such. Even though we agreed to introduce the BC, we shouldn't break existing libraries. So this patch flips the default again and move the new default to ui.tweakdefaults. We could instead use HGPLAIN to turn this flag off, but that would be rather confusing as the old/new behaviors are quite different. Differential Revision: https://phab.mercurial-scm.org/D3919

grep: add config knob to enable/disable the default wdir search This allows us to conditionally enable the new behavior to unbreak python-hglib. See the next patch. The config option is undocumented since the --all-files is still experimental and isn't fully implemented. It can be moved to [experimental] if that's preferred. Differential Revision: https://phab.mercurial-scm.org/D3918

grep: search working directory files by default if --all-files is specified The default was -rtip:0 before, but "--all-files -rtip:0" would be the most useless combination, and it isn't supported yet. Let's change the default to something useful. This isn't flagged as BC since --all-files isn't released. Differential Revision: https://phab.mercurial-scm.org/D3917

grep: reject --diff --all-files This combination doesn't make any sense since --diff is the flag to search change history, whereas --all-files is to include unmodified contents. Differential Revision: https://phab.mercurial-scm.org/D3916

grep: rename --allfiles to --all-files This matches the config name to be added. Note that we don't have to keep the old flag since it isn't released yet. Differential Revision: https://phab.mercurial-scm.org/D3915

debugdeltachain: protect against 0 readsize If you don't read any data, read density should be 1.

debugdeltachain: avoid division by zero when a chain is empty The two ratios chainratio and extraratio are computed using dividers that may be zero when the file is empty. As the denominators are integers, the limit of the ratio "just before zero" is the numerator value itself. If the numerator itself is zero, the ratio value is still meaningful: in both cases, a "good" value is a low ratio, and a size of zero is the optimal case.

tests: prevent conflict markers in test case from triggering warnings Broadly, having lines that begin with several '<' tends to trigger tools that try to warn you about unresolved conflicts. It will save some headaches to tweak this string literal to avoid that. Differential Revision: https://phab.mercurial-scm.org/D3897

revlog: enforce chunk slicing down to a certain size Limit maximum chunk size to 4x final size when reading a revision from a revlog. We only apply this logic when the target size is known from the revlog. Ideally, revlog's delta chain would be written in a way that does not trigger this extra slicing often. However, having this second guarantee that we won't read unexpectedly large amounts of memory in all cases is important for the future. Future delta chain building algorithms might have good reason to create delta chain with such characteristics. Including this code in core as soon as possible will make Mercurial 4.7 forward-compatible with such improvement.

revlog: postprocess chunk to slice them down to a certain size After the density slicing is done, we enforce a maximum chunk size to avoid memory consumption issue.

revlog: add function to slice chunk down to a given size It is possible to encounter situations where the slicing based on density did not achieve chunk smaller than the 4*textlength limit. To avoid extra memory consumption in those cases, we need to be able to break down chunk to a given size. Actual caller comes in the next changesets.

revlog: extract density based slicing into its own function We are going to introduce another slicing step. We start by extracting the existing one into its own function.

revlog: document and test _slicechunk

revlog: add a doctest for _segmentspan

revlog: add a doctest to _trimchunk

revlog: introduce a tiny mock of a revlog class This will be used in various function doctest added in the next changesets. The class seems small enough to live in the module directly.

revlog: _segmentspan computes the byte span of a segment Refactor out this code to be used somewhere else in a next changeset