Mercurial > hg
view mercurial/hbisect.py @ 35569:964212780daf
rust: implementation of `hg`
This commit provides a mostly-working implementation of the
`hg` script in Rust along with scaffolding to support Rust in
the repository.
If you are familiar with Rust, the contents of the added rust/
directory should be pretty straightforward. We create an "hgcli"
package that implements a binary application to run Mercurial.
The output of this package is an "hg" binary.
Our Rust `hg` (henceforth "rhg") essentially is a port of the existing
`hg` Python script. The main difference is the creation of the embedded
CPython interpreter is handled by the binary itself instead of relying
on the shebang. In that sense, rhg is more similar to the "exe wrapper"
we currently use on Windows. However, unlike the exe wrapper, rhg does
not call the `hg` Python script. Instead, it uses the CPython APIs to
import mercurial modules and call appropriate functions. The amount of
code here is surprisingly small.
It is my intent to replace the existing C-based exe wrapper with rhg.
Preferably in the next Mercurial release. This should be achievable -
at least for some Mercurial distributions. The future/timeline for
rhg on other platforms is less clear. We already ship a hg.exe on
Windows. So if we get the quirks with Rust worked out, shipping a
Rust-based hg.exe should hopefully not be too contentious.
Now onto the implementation.
We're using python27-sys and the cpython crates for talking to the
CPython API. We currently don't use too much functionality of the
cpython crate and could have probably cut it out. However, it does
provide a reasonable abstraction over unsafe {} CPython function
calls. While we still have our fair share of those, at least we're
not dealing with too much refcounting, error checking, etc. So I
think the use of the cpython crate is justified. Plus, there is
not-yet-implemented functionality that could benefit from cpython. I
see our use of this crate only increasing.
The cpython and python27-sys crates are not without their issues.
The cpython crate didn't seem to account for the embedding use case
in its design. Instead, it seems to assume that you are building
a Python extension. It is making some questionable decisions around
certain CPython APIs. For example, it insists that
PyEval_ThreadsInitialized() is called and that the Python code
likely isn't the main thread in the underlying application. It
is also missing some functionality that is important for embedded
use cases (such as exporting the path to the Python interpreter
from its build script). After spending several hours trying to
wrangle python27-sys and cpython, I gave up and forked the project
on GitHub. Our Cargo.toml tracks this fork. I'm optimistic that
the upstream project will accept our contributions and we can
eventually unfork.
There is a non-trivial amount of code in our custom Cargo build
script. Our build.rs (which is called as part of building the hgcli
crate):
* Validates that the Python interpreter that was detected by the
python27-sys crate provides a shared library (we only support
shared library linking at this time - although this restriction
could be loosened).
* Validates that the Python is built with UCS-4 support. This ensures
maximum Unicode compatibility.
* Exports variables to the crate build allowing the built crate to e.g.
find the path to the Python interpreter.
The produced rhg should be considered alpha quality. There are several
known deficiencies. Many of these are documented with inline TODOs.
Probably the biggest limitation of rhg is that it assumes it is
running from the ./rust/target/<target> directory of a source
distribution. So, rhg is currently not very practical for real-world
use. But, if you can `cargo build` it, running the binary *should*
yield a working Mercurial CLI.
In order to support using rhg with the test harness, we needed to hack
up run-tests.py so the path to Mercurial's Python files is set properly.
The change is extremely hacky and is only intended to be a stop-gap
until the test harness gains first-class support for installing rhg.
This will likely occur after we support running rhg outside the
source directory.
Despite its officially alpha quality, rhg copes extremely well with
the test harness (at least on Linux). Using
`run-tests.py --with-hg ../rust/target/debug/hg`, I only encounter
the following failures:
* test-run-tests.t -- Warnings emitted about using an unexpected
Mercurial library. This is due to the hacky nature of setting the
Python directory when run-tests.py detected rhg.
* test-devel-warnings.t -- Expected stack trace missing frame for `hg`
(This is expected since we no longer have an `hg` script!)
* test-convert.t -- Test running `$PYTHON "$BINDIR"/hg`, which obviously
assumes `hg` is a Python script.
* test-merge-tools.t -- Same assumption about `hg` being executable with
Python.
* test-http-bad-server.t -- Seeing exit code 255 instead of 1 around
line 358.
* test-blackbox.t -- Exit code 255 instead of 1.
* test-basic.t -- Exit code 255 instead of 1.
It certainly looks like we have a bug around exit code handling. I
don't think it is severe enough to hold up review and landing of this
initial implementation. Perfect is the enemy of good.
Differential Revision: https://phab.mercurial-scm.org/D1581
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 10 Jan 2018 08:53:22 -0800 |
parents | 8287df8b7be5 |
children | 80da79b6fbe4 |
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# changelog bisection for mercurial # # Copyright 2007 Matt Mackall # Copyright 2005, 2006 Benoit Boissinot <benoit.boissinot@ens-lyon.org> # # Inspired by git bisect, extension skeleton taken from mq.py. # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import collections from .i18n import _ from .node import ( hex, short, ) from . import ( error, ) def bisect(repo, state): """find the next node (if any) for testing during a bisect search. returns a (nodes, number, good) tuple. 'nodes' is the final result of the bisect if 'number' is 0. Otherwise 'number' indicates the remaining possible candidates for the search and 'nodes' contains the next bisect target. 'good' is True if bisect is searching for a first good changeset, False if searching for a first bad one. """ changelog = repo.changelog clparents = changelog.parentrevs skip = set([changelog.rev(n) for n in state['skip']]) def buildancestors(bad, good): badrev = min([changelog.rev(n) for n in bad]) ancestors = collections.defaultdict(lambda: None) for rev in repo.revs("descendants(%ln) - ancestors(%ln)", good, good): ancestors[rev] = [] if ancestors[badrev] is None: return badrev, None return badrev, ancestors good = False badrev, ancestors = buildancestors(state['bad'], state['good']) if not ancestors: # looking for bad to good transition? good = True badrev, ancestors = buildancestors(state['good'], state['bad']) bad = changelog.node(badrev) if not ancestors: # now we're confused if (len(state['bad']) == 1 and len(state['good']) == 1 and state['bad'] != state['good']): raise error.Abort(_("starting revisions are not directly related")) raise error.Abort(_("inconsistent state, %s:%s is good and bad") % (badrev, short(bad))) # build children dict children = {} visit = collections.deque([badrev]) candidates = [] while visit: rev = visit.popleft() if ancestors[rev] == []: candidates.append(rev) for prev in clparents(rev): if prev != -1: if prev in children: children[prev].append(rev) else: children[prev] = [rev] visit.append(prev) candidates.sort() # have we narrowed it down to one entry? # or have all other possible candidates besides 'bad' have been skipped? tot = len(candidates) unskipped = [c for c in candidates if (c not in skip) and (c != badrev)] if tot == 1 or not unskipped: return ([changelog.node(c) for c in candidates], 0, good) perfect = tot // 2 # find the best node to test best_rev = None best_len = -1 poison = set() for rev in candidates: if rev in poison: # poison children poison.update(children.get(rev, [])) continue a = ancestors[rev] or [rev] ancestors[rev] = None x = len(a) # number of ancestors y = tot - x # number of non-ancestors value = min(x, y) # how good is this test? if value > best_len and rev not in skip: best_len = value best_rev = rev if value == perfect: # found a perfect candidate? quit early break if y < perfect and rev not in skip: # all downhill from here? # poison children poison.update(children.get(rev, [])) continue for c in children.get(rev, []): if ancestors[c]: ancestors[c] = list(set(ancestors[c] + a)) else: ancestors[c] = a + [c] assert best_rev is not None best_node = changelog.node(best_rev) return ([best_node], tot, good) def extendrange(repo, state, nodes, good): # bisect is incomplete when it ends on a merge node and # one of the parent was not checked. parents = repo[nodes[0]].parents() if len(parents) > 1: if good: side = state['bad'] else: side = state['good'] num = len(set(i.node() for i in parents) & set(side)) if num == 1: return parents[0].ancestor(parents[1]) return None def load_state(repo): state = {'current': [], 'good': [], 'bad': [], 'skip': []} for l in repo.vfs.tryreadlines("bisect.state"): kind, node = l[:-1].split() node = repo.lookup(node) if kind not in state: raise error.Abort(_("unknown bisect kind %s") % kind) state[kind].append(node) return state def save_state(repo, state): f = repo.vfs("bisect.state", "w", atomictemp=True) with repo.wlock(): for kind in sorted(state): for node in state[kind]: f.write("%s %s\n" % (kind, hex(node))) f.close() def resetstate(repo): """remove any bisect state from the repository""" if repo.vfs.exists("bisect.state"): repo.vfs.unlink("bisect.state") def checkstate(state): """check we have both 'good' and 'bad' to define a range Raise Abort exception otherwise.""" if state['good'] and state['bad']: return True if not state['good']: raise error.Abort(_('cannot bisect (no known good revisions)')) else: raise error.Abort(_('cannot bisect (no known bad revisions)')) def get(repo, status): """ Return a list of revision(s) that match the given status: - ``good``, ``bad``, ``skip``: csets explicitly marked as good/bad/skip - ``goods``, ``bads`` : csets topologically good/bad - ``range`` : csets taking part in the bisection - ``pruned`` : csets that are goods, bads or skipped - ``untested`` : csets whose fate is yet unknown - ``ignored`` : csets ignored due to DAG topology - ``current`` : the cset currently being bisected """ state = load_state(repo) if status in ('good', 'bad', 'skip', 'current'): return map(repo.changelog.rev, state[status]) else: # In the following sets, we do *not* call 'bisect()' with more # than one level of recursion, because that can be very, very # time consuming. Instead, we always develop the expression as # much as possible. # 'range' is all csets that make the bisection: # - have a good ancestor and a bad descendant, or conversely # that's because the bisection can go either way range = '( bisect(bad)::bisect(good) | bisect(good)::bisect(bad) )' _t = repo.revs('bisect(good)::bisect(bad)') # The sets of topologically good or bad csets if len(_t) == 0: # Goods are topologically after bads goods = 'bisect(good)::' # Pruned good csets bads = '::bisect(bad)' # Pruned bad csets else: # Goods are topologically before bads goods = '::bisect(good)' # Pruned good csets bads = 'bisect(bad)::' # Pruned bad csets # 'pruned' is all csets whose fate is already known: good, bad, skip skips = 'bisect(skip)' # Pruned skipped csets pruned = '( (%s) | (%s) | (%s) )' % (goods, bads, skips) # 'untested' is all cset that are- in 'range', but not in 'pruned' untested = '( (%s) - (%s) )' % (range, pruned) # 'ignored' is all csets that were not used during the bisection # due to DAG topology, but may however have had an impact. # E.g., a branch merged between bads and goods, but whose branch- # point is out-side of the range. iba = '::bisect(bad) - ::bisect(good)' # Ignored bads' ancestors iga = '::bisect(good) - ::bisect(bad)' # Ignored goods' ancestors ignored = '( ( (%s) | (%s) ) - (%s) )' % (iba, iga, range) if status == 'range': return repo.revs(range) elif status == 'pruned': return repo.revs(pruned) elif status == 'untested': return repo.revs(untested) elif status == 'ignored': return repo.revs(ignored) elif status == "goods": return repo.revs(goods) elif status == "bads": return repo.revs(bads) else: raise error.ParseError(_('invalid bisect state')) def label(repo, node): rev = repo.changelog.rev(node) # Try explicit sets if rev in get(repo, 'good'): # i18n: bisect changeset status return _('good') if rev in get(repo, 'bad'): # i18n: bisect changeset status return _('bad') if rev in get(repo, 'skip'): # i18n: bisect changeset status return _('skipped') if rev in get(repo, 'untested') or rev in get(repo, 'current'): # i18n: bisect changeset status return _('untested') if rev in get(repo, 'ignored'): # i18n: bisect changeset status return _('ignored') # Try implicit sets if rev in get(repo, 'goods'): # i18n: bisect changeset status return _('good (implicit)') if rev in get(repo, 'bads'): # i18n: bisect changeset status return _('bad (implicit)') return None def shortlabel(label): if label: return label[0].upper() return None def printresult(ui, repo, state, displayer, nodes, good): if len(nodes) == 1: # narrowed it down to a single revision if good: ui.write(_("The first good revision is:\n")) else: ui.write(_("The first bad revision is:\n")) displayer.show(repo[nodes[0]]) extendnode = extendrange(repo, state, nodes, good) if extendnode is not None: ui.write(_('Not all ancestors of this changeset have been' ' checked.\nUse bisect --extend to continue the ' 'bisection from\nthe common ancestor, %s.\n') % extendnode) else: # multiple possible revisions if good: ui.write(_("Due to skipped revisions, the first " "good revision could be any of:\n")) else: ui.write(_("Due to skipped revisions, the first " "bad revision could be any of:\n")) for n in nodes: displayer.show(repo[n]) displayer.close()