storageutil: implement file identifier resolution method (BC) revlog.lookup() has a number of advanced features, including partial node matching. These advanced features aren't needed for file id lookup because file identifiers are almost always from internal sources. (An exception to this is hgweb, which appears to have some code paths that attempt to resolve a user-supplied string to a node.) This commit implements a new function for resolving file identifiers to nodes. It behaves like revlog.lookup() but without the advanced features. Tests reveal behavior changes: * Partial hex nodes are no longer resolved to nodes. * "-1" now returns nullid instead of raising LookupError. * "0" on an empty store now raises LookupError instead of returning nullid. I'm not sure why "-1" wasn't recognized before. But it seems reasonable to accept it as a value since integer -1 resolves to nullid. These changes all seem reasonable to me. And with the exception of partial hex node matching, we may want to consider changing revlog.lookup() as well. Differential Revision: https://phab.mercurial-scm.org/D4797

testing: add more testing for ifileindex.lookup() The tests demonstrate some... questionable behavior of revlog.lookup(). Differential Revision: https://phab.mercurial-scm.org/D4796

dagop: extract DAG local heads functionality from revlog As part of implementing an alternate storage backend, I found myself having to reimplement this function. The DAG traversal logic is generic and can be factored out into a standalone function. We could probably combine this with headrevs(). But I'll leave that for another time. Differential Revision: https://phab.mercurial-scm.org/D4795

dagop: extract descendants() from revlog module This method needs to be implemented in other storage backends and is generic if we parameterize the functions for retrieving revision numbers and parent revision numbers. Let's extract it to dagop so backends don't need to reinvent the wheel. I'm not too worried about performance overhead of the extra function call because I don't expect anyone to be calling descendants() in a tight loop. Differential Revision: https://phab.mercurial-scm.org/D4794

filelog: remove checkhash() (API) It is unused. While a caller may want to ask the store to validate the hash of some provided text, since there are no in-core consumers of this method, let's drop it for now. Differential Revision: https://phab.mercurial-scm.org/D4793

filelog: remove revdiff() (API) This proxy method is no longer used. While it might be useful to query a storage backend for the delta between any 2 revisions because the store could have a delta cached and could compute it more efficiently than the caller calling revision() twice in order to compute a delta, since nothing in core is using this API now, I feel comfortable nuking it. Differential Revision: https://phab.mercurial-scm.org/D4792

localrepo: define storage backend in creation options (API) We add an experimental config option to define the storage backend for new repositories. By default, it uses "revlogv1," which maps to the current and only modern supported repository format. We add a "backend" creation option to control which backend to use. It defaults to using the value from the config option. newreporequirements() will now barf if it sees a "backend" value that isn't "revlogv1." This forces extensions to monkeypatch the function to handle requirements derivation for custom backends. In order for this to "just work," we factored out obtaining the default creation options into its own function and made callers of newreporequirements() responsible for passing in valid data. Without this, direct callers of newreporequirements() wouldn't get the proper results. Differential Revision: https://phab.mercurial-scm.org/D4791

wireprotov2: derive "required" from presence of default value If we define a default value for all optional arguments, we no longer need to explicitly declare whether the argument is required. Instead, we can derive it from the presence of a default value callable. Differential Revision: https://phab.mercurial-scm.org/D4790

localrepo: capture repo interface factory functions as lambas Previously, the list would hold a reference to the original function and attempting to wrap the module function via extension wouldn't result in the wrapped function being called, completely undermining the expected behavior. Differential Revision: https://phab.mercurial-scm.org/D4821

extensions: new closehead module for closing arbitrary heads ``hg close-head`` allows closing arbitrary heads. It is equivalent to checking out the given revisions and commit an empty change with ``hg commit --close-branch``. Differential Revision: https://phab.mercurial-scm.org/D3557

cext: use modern buffer protocol in mpatch_flist() Differential Revision: https://phab.mercurial-scm.org/D4841

cext: use modern buffer protocol in patches() PyObject_AsCharBuffer() is part of the "Old Buffer Protocol," which has been deprecated for years. Let's port away from it. PyBuffer_GetBuffer() must be paired with PyBuffer_Release(), hence the added "goto cleanup" in a failure case. We don't bump the extension version because the API has not changed. Differential Revision: https://phab.mercurial-scm.org/D4840

identify: when using -T, avoid unnecessary remote bookmarks query Differential Revision: https://phab.mercurial-scm.org/D4839

identify: only query remote bookmarks if needed Instead of all the time when operating on a remote repo. This perf regression was introduced in 15a79ac823e8, in 4.3. This datahint method returns nothing for -Tjson, -Tpickle, -Tdebug --config ui.formatdebug=true and --config ui.formatjson, so the bookmarks won't show up. I don't know what these formatters are for. plainformatter and templateformatter work properly, and the few other uses of datahint should have the same kind of problem. There is further weirdness where "--template '{node}'" is not enough to avoid querying the bookmarks, you also need to pass --id or -q. Differential Revision: https://phab.mercurial-scm.org/D4819

py3: whitelist another passing tests caught by buildbot I this indygreg recent patches made this test pass on Python 3. So thanks to him! Differential Revision: https://phab.mercurial-scm.org/D4848

manifest: remove an unused variable caught by pyflakes Uses of todel were removed in D4843 (19103e68a698). This patch will make buildbots green again. Differential Revision: https://phab.mercurial-scm.org/D4847

setup: ignore message about disabling 3rd party extensions because of version I started getting into a bind recently when switching between py2 and py3 because switching requires a `make clean`, which kills __version__.py. But then when running `make local`, it picks up the local hg.exe (MSYS seems to prefix $PATH with '.'), which doesn't know its version. That causes it to emit a warning about needing at least 4.3 to load evolve, which caused setup.py to fail saying there is no working hg executable to figure out the version. If we can ignore general extension import failures, we should be able to ignore this too.

narrow: avoid overwriting a variable I don't like to overwrite variables, especially not with a different type (because it makes it harder to explain what the variable is for, and, therefore, to name it well). Differential Revision: https://phab.mercurial-scm.org/D4846

treemanifests: remove _loadalllazy in _diff() The benchmarks below use a similar setup as in ee7ee0c516ca and my other recent commits. Yes, in some cases this runs in literally 5% of the time it previously took. before = a6f8ab53 diff --git: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 1.301 s +- 0.004 s | 1.309 s +- 0.012 s | 100.6% m-u | | x | 1.303 s +- 0.009 s | 1.302 s +- 0.006 s | 99.9% m-u | x | | 1.308 s +- 0.006 s | 1.309 s +- 0.007 s | 100.1% m-u | x | x | 85.7 ms +- 0.6 ms | 86.0 ms +- 0.3 ms | 100.4% l-d-r | | | 197.5 ms +- 0.7 ms | 197.8 ms +- 2.2 ms | 100.2% l-d-r | | x | 199.4 ms +- 0.6 ms | 199.3 ms +- 0.9 ms | 99.9% l-d-r | x | | 86.1 ms +- 0.5 ms | 85.8 ms +- 0.9 ms | 99.7% l-d-r | x | x | 64.4 ms +- 0.4 ms | 64.4 ms +- 0.3 ms | 100.0% diff -c . --git: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 236.7 ms +- 1.1 ms | 236.5 ms +- 1.3 ms | 99.9% m-u | | x | 158.7 ms +- 1.0 ms | 128.0 ms +- 1.0 ms | 80.7% <-- m-u | x | | 239.7 ms +- 1.8 ms | 238.1 ms +- 1.5 ms | 99.3% m-u | x | x | 132.4 ms +- 0.9 ms | 132.3 ms +- 0.6 ms | 99.9% l-d-r | | | 81.8 ms +- 0.4 ms | 81.8 ms +- 0.3 ms | 100.0% l-d-r | | x | 3.894 s +- 0.017 s | 193.6 ms +- 0.4 ms | 5.0% <-- l-d-r | x | | 106.9 ms +- 0.4 ms | 106.6 ms +- 0.3 ms | 99.7% l-d-r | x | x | 182.7 ms +- 0.8 ms | 183.3 ms +- 0.9 ms | 100.3% rebase -r . --keep -d .^^: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 5.615 s +- 0.109 s | 5.562 s +- 0.015 s | 99.1% m-u | | x | 5.701 s +- 0.027 s | 5.715 s +- 0.023 s | 100.2% m-u | x | | 5.572 s +- 0.128 s | 5.613 s +- 0.182 s | 100.7% m-u | x | x | 633.3 ms +- 28.7 ms | 636.2 ms +- 13.8 ms | 100.5% l-d-r | | | 666.4 ms +- 17.0 ms | 658.5 ms +- 9.3 ms | 98.8% l-d-r | | x | 6.520 s +- 0.070 s | 6.505 s +- 0.026 s | 99.8% l-d-r | x | | 279.0 ms +- 13.0 ms | 276.5 ms +- 4.7 ms | 99.1% l-d-r | x | x | 1.636 s +- 0.058 s | 1.657 s +- 0.014 s | 101.3% status --change . --copies: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 218.6 ms +- 1.4 ms | 217.9 ms +- 1.5 ms | 99.7% m-u | | x | 138.5 ms +- 0.4 ms | 108.4 ms +- 0.2 ms | 78.3% <-- m-u | x | | 220.1 ms +- 1.3 ms | 219.7 ms +- 1.5 ms | 99.8% m-u | x | x | 113.2 ms +- 0.4 ms | 112.4 ms +- 0.8 ms | 99.3% l-d-r | | | 80.2 ms +- 0.3 ms | 80.6 ms +- 0.6 ms | 100.5% l-d-r | | x | 3.899 s +- 0.020 s | 194.8 ms +- 4.0 ms | 5.0% <-- l-d-r | x | | 83.4 ms +- 0.8 ms | 83.2 ms +- 0.2 ms | 99.8% l-d-r | x | x | 732.2 ms +- 4.3 ms | 194.9 ms +- 1.0 ms | 26.6% <-- status --copies: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 1.917 s +- 0.005 s | 1.914 s +- 0.004 s | 99.8% m-u | | x | 1.909 s +- 0.012 s | 1.934 s +- 0.004 s | 101.3% m-u | x | | 1.915 s +- 0.005 s | 1.904 s +- 0.004 s | 99.4% m-u | x | x | 94.8 ms +- 0.3 ms | 94.7 ms +- 0.2 ms | 99.9% l-d-r | | | 593.9 ms +- 1.2 ms | 594.6 ms +- 9.4 ms | 100.1% l-d-r | | x | 595.2 ms +- 3.8 ms | 597.2 ms +- 2.6 ms | 100.3% l-d-r | x | | 182.5 ms +- 1.6 ms | 182.1 ms +- 0.6 ms | 99.8% l-d-r | x | x | 149.6 ms +- 0.9 ms | 149.1 ms +- 0.8 ms | 99.7% update $rev^; ~/src/hg/hg{hg}/hg update $rev: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 3.121 s +- 0.007 s | 3.129 s +- 0.012 s | 100.3% m-u | | x | 2.972 s +- 0.011 s | 2.981 s +- 0.012 s | 100.3% m-u | x | | 3.144 s +- 0.014 s | 3.141 s +- 0.011 s | 99.9% m-u | x | x | 312.2 ms +- 2.4 ms | 312.3 ms +- 2.1 ms | 100.0% l-d-r | | | 444.4 ms +- 4.3 ms | 446.9 ms +- 5.3 ms | 100.6% l-d-r | | x | 9.159 s +- 0.069 s | 9.182 s +- 0.040 s | 100.3% l-d-r | x | | 254.6 ms +- 1.6 ms | 255.2 ms +- 1.6 ms | 100.2% l-d-r | x | x | 1.525 s +- 0.007 s | 1.577 s +- 0.007 s | 103.4% <--? Differential Revision: https://phab.mercurial-scm.org/D4845

treemanifests: skip extraneous check for item before calling _loadlazy Differential Revision: https://phab.mercurial-scm.org/D4844

treemanifests: make _loadchildrensetlazy just call _loadlazy This was suggested on the original review for _loadchildrensetlazy (D4370), it's taken me a while to get to it though. Differential Revision: https://phab.mercurial-scm.org/D4843

treemanifests: make _loadlazy tolerate item not on _lazydirs I'd like to clean up a few cases where we check for an item in _lazydirs before calling _loadlazy - this will remove an extraneous dict lookup and make it slightly more versatile. Differential Revision: https://phab.mercurial-scm.org/D4842

debugcommands: add a debugindexstats command Someone went through the trouble of recording these stats, so let's make them accessible. Differential Revision: https://phab.mercurial-scm.org/D4832

rust-chg: add main program It can at least connect to a *running* command server, and execute Mercurial command. No signal handling nor daemon management is implemented yet.

rust-chg: add interface to chdir the server

rust-chg: add Client extensions to run cHg-specific requests This just provides a nicer way to issue command-server requests.

rust-chg: port basic socket path handling from cHg of C This is basically modeled after setcmdserveropts() of chg.c.

rust-chg: add state machine to handle "runcommand" request with cHg extension This is modeled after tokio-hglib's RunCommand state to support the "S" channel message.

rust-chg: add callback to handle pager and shell command requests This could be inlined into the ChgRunCommand state to be introduced by the next patch, but it seemed good to separate any user interactions from the IPC code.

rust-chg: add low-level function to set pager fd blocking This is necessary because the server expects stdout/stderr to be blocking, whereas we'll use async library to spawn pager, which makes pipes unblocking.