remotefilelog: drop some compatibility cruft for finding the hg exeutable

branchmap: build the revbranchcache._namesreverse() only when required On big repositories with a lot of named branches and that also increasing over time, building of this dict can be expensive and shows up in profile. For our internal repository, this saves ~0.05 seconds. Thanks to Yuya for suggesting using util.propertycache() and util.clearcachedproperty(). Differential Revision: https://phab.mercurial-scm.org/D5291

sparse-revlog: put the native implementation of slicechunktodensity to use When possible, the C implementation of delta chain slicing will be used. providing a large boost in performance for this operation. To take a practical example of restoring manifest revision '59547c40bc4c' for a reference NetBeans repository (using sparse-revlog). The media time of the step `slice-sparse-chain` of `perfrevlogrevision` improve from 0.660 ms to 0.098 ms; The full series move delta chain slicing from 1.120 ms to 0.098 ms; Implementing _slicechunktosize into C would yield further improvements. However, the performance seems good enough for now.

cext: increment the `parsers` module version We introduced a new `slicechunktodensity` method to the index.

sparse-revlog: introduce native (C) implementation of slicechunktodensity This is a C implementation of `_slicechunktodensity` in the `mercurial/revlogutils/deltas.py` file. The algorithm involves a lot of integer manipulation and low-level access to index data. Having a C implementation of it raises a large performance improvement. See later changeset in this series for details.

sparse-revlog: add a `trim_endidx` function in C We are about to implement a native version of `slicechunktodensity`. For clarity, we introduce the helper functions first. This function implement a subpart of the python function `_trimchunk` in `mercurial/revlogutils/deltas.py`. Handling of actual Python objects is left to the caller function.

sparse-revlog: add a `index_segment_span` function in C We are about to implement a native version of `slicechunktodensity`. For clarity, we introduce the helper functions first. This new function provides an efficient way to retrieve some of the information needed by `slicechunktodensity`.

sparse-revlog: add a `index_get_length` function in C We are about to implement a native version of `slicechunktodensity`. For clarity, we introduce the helper functions first. This new function provides an efficient way to retrieve some of the information needed by `slicechunktodensity`.

sparse-revlog: add a `index_get_start` function in C We are about to implement a native version of `slicechunktodensity`. For clarity, we introduce the helper functions first. This new function provides an efficient way to retrieve some of the information needed by `slicechunktodensity`.

perf: add --clear-revlog flag to branchmapload Having the changelog index already loaded when loading the branchmap can have a large impact on performance. Example runs (large private repository): hg perfbranchmapload -f base ! wall 0.116722 comb 0.120000 user 0.110000 sys 0.010000 (best of 59) hg perfbranchmapload -f base --clear-revlogs ! wall 0.258246 comb 0.230000 user 0.220000 sys 0.010000 (best of 31)

perf: introduce a function to fully "unload" a changelog The function remove various attributes and caches related to changelog. This is getting a common requirement.

perf: use an explicit function in perfbranchmapload This make things clearer.

perf: update function name to match `perfbranchmapload` command Having function with the same name as the command is simpler.

perf: fix a minor typo in perfbranchmapload

context: floor adjustlinkrev graph walk during copy tracing The `_adjustlinkrev` method gains an optional "stoprev" argument. The linkrev adjustment will give up once this floor is reached. The relevant functions using `_adjustlinkrev` are updated to pass an appropriate value in the copy tracing code. In some private repository, about 10% of the status call triggered the pathological case addressed by this change. The speedup varies from one call to another, the best-observed win is moving from 170s to 11s. The effect of this change can be seen in the public pypy repository, running the following command: hg perftracecopies --source 83c9ff0c0206 --destination 59c79103d5b0 before: 3.401753 seconds after: 2.634897 seconds (-23%)

context: small refactoring of `isintroducedafter` This make the next change clearer.

context: split `introrev` logic in a sub function We want to add a mechanism to stop iteration early associated to intro rev early in some case. However, it does not make sense to expose it in the public `filectx` API. So we split the code into an internal method instead.

context: introduce an `isintroducedafter` method and use it in copies Right now, copy tracing make effort to not traverse the graph too much to save performance. It uses a "limit" acting as a floor revision past which data are no longer relevant to the current copy tracing. However, to enforce this limit, it does a call to `filectx.rev()` and that call can trigger a graph traversal on its own. That extra graph traversal is unaware of the current limit and can become very expensive. That cost is increased by the nature of work done in adjust link rev, we are not only walking down the graph, we are also checking the affected file for each revision we walk through. Something significantly more expensive than the walk itself. To work around this we need to make the `filectx` operation aware of the current limit. The first step is to introduce a dedicated method: `isintroducedafter`. We'll then rework that method logic to stop traversal as soon as possible.

context: take advantage of `_descendantrev` in introrev if available Before this changeset, `_descendantrev` was ignored and `introrev` could return a "wrong" result. I was previously fine because there seems to be no existing code using both `introrev` and `_descendantrev` at the same time. However, we would like to change that.

context: spell out the logic around linkrev adjustement starting point We make the intent of the `_changeid` and `_changectx` checks explicit. The same logic was previously performed by the `self.rev()` call. The new code is a bit redundant, but much clearer.

perf: add a new `perfhelper-tracecopies` command The command is not measuring performance itself, it digs interesting statistic to help pick good arguments for the `perfcopytrace` command.

narrow: extract helper for parsing narrowspec file This will be used for parsing a file that's stored in a different location. Differential Revision: https://phab.mercurial-scm.org/D5277

py3: cast attribute name to sysstr in clearcachedproperty()

py3: whitelist three more passing test caught by buildbot The number of failing test is back to two digits. Differential Revision: https://phab.mercurial-scm.org/D5293

tests: make test-check-module-imports more robust It failed for me without this in this way: tests/test-commandserver.t:19: relative import of stdlib module tests/test-lfs-serve.t:108: relative import of stdlib module tests/test-lfs-serve.t:255: relative import of stdlib module tests/test-lfs-serve.t:362: relative import of stdlib module tests/test-lfs-serve.t:406: relative import of stdlib module tests/test-lock.py:9: imports not lexically sorted: silenttestrunner < unittest, True, True tests/test-lrucachedict.py:5: imports not lexically sorted: silenttestrunner < unittest, True, True tests/test-match.py:5: imports not lexically sorted: silenttestrunner < unittest, True, True tests/test-remotefilelog-datapack.py:15: imports not lexically sorted: silenttestrunner < unittest, True, True tests/test-remotefilelog-histpack.py:14: imports not lexically sorted: silenttestrunner < unittest, True, True tests/test-simplekeyvaluefile.py:4: imports not lexically sorted: silenttestrunner < unittest, True, True tests/test-sshserver.py:6: imports not lexically sorted: silenttestrunner < unittest, True, True This is because every module is considered a stdlib module, because the stdlib_prefixes is /usr, and my repo is in /usr/local/home, which means that sys.path contains a couple of /usr/local/home/../hg/.. entries that count as "in the stdlib". Fix this by preventing any path in sys.path that's inside the mercurial source from being considered "in the stdlib". Differential Revision: https://phab.mercurial-scm.org/D5294

push: add --publish flag to change phase of pushed changesets This flag is copied from topic extension, where it proved to be useful. It makes all pushed changesets public on both ends if the push succeeds. Doesn't currently work for any subrepos that are implicitly pushed together with their owner repo.

match: reformat `syntaxes` dictionary for better maintainability

match: provide and use a quick way to escape a single byte The previous function has a lot of overhead (including being a function). In the `_globre` case, we always escape a single byte. So we provide a dictionary dedicated to this use case. We directly use the dictionary to avoid a function call, these are expensive in Python. Again, this raise a very significant performance gain: Before: ! wall 0.059793 comb 0.060000 user 0.060000 sys 0.000000 (median of 100) After: ! wall 0.020390 comb 0.020000 user 0.020000 sys 0.000000 (median of 146) Total improvement for the full series: Before: ! wall 0.153153 comb 0.150000 user 0.150000 sys 0.000000 (median of 66) After: ! wall 0.020390 comb 0.020000 user 0.020000 sys 0.000000 (median of 146)