Mercurial > hg
view tests/drawdag.py @ 49000:dd6b67d5c256 stable
rust: fix unsound `OwningDirstateMap`
As per the previous patch, `OwningDirstateMap` is unsound. Self-referential
structs are difficult to implement correctly in Rust since the compiler is
free to move structs around as much as it wants to. They are also very rarely
needed in practice, so the state-of-the-art on how they should be done within
the Rust rules is still a bit new.
The crate `ouroboros` is an attempt at providing a safe way (in the Rust sense)
of declaring self-referential structs. It is getting a lot attention and was
improved very quickly when soundness issues were found in the past: rather than
relying on our own (limited) review circle, we might as well use the de-facto
common crate to fix this problem. This will give us a much better chance of
finding issues should any new ones be discovered as well as the benefit of
fewer `unsafe` APIs of our own.
I was starting to think about how I would present a safe API to the old struct
but soon realized that the callback-based approach was already done in
`ouroboros`, along with a lot more care towards refusing incorrect structs.
In short: we don't return a mutable reference to the `DirstateMap` anymore, we
expect users of its API to pass a `FnOnce` that takes the map as an argument.
This allows our `OwningDirstateMap` to control the input and output lifetimes
of the code that modifies it to prevent such issues.
Changing to `ouroboros` meant changing every API with it, but it is relatively
low churn in the end. It correctly identified the example buggy modification of
`copy_map_insert` outlined in the previous patch as violating the borrow rules.
Differential Revision: https://phab.mercurial-scm.org/D12429
author | Raphaël Gomès <rgomes@octobus.net> |
---|---|
date | Tue, 05 Apr 2022 10:55:28 +0200 |
parents | d55b71393907 |
children | 6000f5b25c9b |
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# drawdag.py - convert ASCII revision DAG to actual changesets # # Copyright 2016 Facebook, Inc. # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. """ create changesets from an ASCII graph for testing purpose. For example, given the following input:: c d |/ b | a 4 changesets and 4 local tags will be created. `hg log -G -T "{rev} {desc} (tag: {tags})"` will output:: o 3 d (tag: d tip) | | o 2 c (tag: c) |/ o 1 b (tag: b) | o 0 a (tag: a) For root nodes (nodes without parents) in the graph, they can be revsets pointing to existing nodes. The ASCII graph could also have disconnected components with same names referring to the same changeset. Therefore, given the repo having the 4 changesets (and tags) above, with the following ASCII graph as input:: foo bar bar foo | / | | ancestor(c,d) a baz The result (`hg log -G -T "{desc}"`) will look like:: o foo |\ +---o bar | | | | o | baz | / +---o d | | +---o c | | o | b |/ o a Note that if you take the above `hg log` output directly as input. It will work as expected - the result would be an isomorphic graph:: o foo |\ | | o d | |/ | | o c | |/ | | o bar | |/| | o | b | |/ o / baz / o a This is because 'o' is specially handled in the input: instead of using 'o' as the node name, the word to the right will be used. Some special comments could have side effects: - Create obsmarkers # replace: A -> B -> C -> D # chained 1 to 1 replacements # split: A -> B, C # 1 to many # prune: A, B, C # many to nothing """ from __future__ import absolute_import, print_function import collections import itertools import re from mercurial.i18n import _ from mercurial import ( context, error, obsolete, pycompat, registrar, scmutil, tags as tagsmod, ) cmdtable = {} command = registrar.command(cmdtable) _pipechars = b'\\/+-|' _nonpipechars = b''.join( pycompat.bytechr(i) for i in range(33, 127) if pycompat.bytechr(i) not in _pipechars ) def _isname(ch): """char -> bool. return True if ch looks like part of a name, False otherwise""" return ch in _nonpipechars def _parseasciigraph(text): r"""str -> {str : [str]}. convert the ASCII graph to edges >>> import pprint >>> pprint.pprint({pycompat.sysstr(k): [pycompat.sysstr(vv) for vv in v] ... for k, v in _parseasciigraph(br''' ... G ... | ... I D C F # split: B -> E, F, G ... \ \| | # replace: C -> D -> H ... H B E # prune: F, I ... \|/ ... A ... ''').items()}) {'A': [], 'B': ['A'], 'C': ['B'], 'D': ['B'], 'E': ['A'], 'F': ['E'], 'G': ['F'], 'H': ['A'], 'I': ['H']} >>> pprint.pprint({pycompat.sysstr(k): [pycompat.sysstr(vv) for vv in v] ... for k, v in _parseasciigraph(br''' ... o foo ... |\ ... +---o bar ... | | | ... | o | baz ... | / ... +---o d ... | | ... +---o c ... | | ... o | b ... |/ ... o a ... ''').items()}) {'a': [], 'b': ['a'], 'bar': ['b', 'a'], 'baz': [], 'c': ['b'], 'd': ['b'], 'foo': ['baz', 'b']} """ lines = text.splitlines() edges = collections.defaultdict(list) # {node: []} def get(y, x): """(int, int) -> char. give a coordinate, return the char. return a space for anything out of range""" if x < 0 or y < 0: return b' ' try: return lines[y][x : x + 1] or b' ' except IndexError: return b' ' def getname(y, x): """(int, int) -> str. like get(y, x) but concatenate left and right parts. if name is an 'o', try to replace it to the right""" result = b'' for i in itertools.count(0): ch = get(y, x - i) if not _isname(ch): break result = ch + result for i in itertools.count(1): ch = get(y, x + i) if not _isname(ch): break result += ch if result == b'o': # special handling, find the name to the right result = b'' for i in itertools.count(2): ch = get(y, x + i) if ch == b' ' or ch in _pipechars: if result or x + i >= len(lines[y]): break else: result += ch return result or b'o' return result def parents(y, x): """(int, int) -> [str]. follow the ASCII edges at given position, return a list of parents""" visited = {(y, x)} visit = [] result = [] def follow(y, x, expected): """conditionally append (y, x) to visit array, if it's a char in excepted. 'o' in expected means an '_isname' test. if '-' (or '+') is not in excepted, and get(y, x) is '-' (or '+'), the next line (y + 1, x) will be checked instead.""" ch = get(y, x) if any(ch == c and c not in expected for c in (b'-', b'+')): y += 1 return follow(y + 1, x, expected) if ch in expected or (b'o' in expected and _isname(ch)): visit.append((y, x)) # -o- # starting point: # /|\ # follow '-' (horizontally), and '/|\' (to the bottom) follow(y + 1, x, b'|') follow(y + 1, x - 1, b'/') follow(y + 1, x + 1, b'\\') follow(y, x - 1, b'-') follow(y, x + 1, b'-') while visit: y, x = visit.pop() if (y, x) in visited: continue visited.add((y, x)) ch = get(y, x) if _isname(ch): result.append(getname(y, x)) continue elif ch == b'|': follow(y + 1, x, b'/|o') follow(y + 1, x - 1, b'/') follow(y + 1, x + 1, b'\\') elif ch == b'+': follow(y, x - 1, b'-') follow(y, x + 1, b'-') follow(y + 1, x - 1, b'/') follow(y + 1, x + 1, b'\\') follow(y + 1, x, b'|') elif ch == b'\\': follow(y + 1, x + 1, b'\\|o') elif ch == b'/': follow(y + 1, x - 1, b'/|o') elif ch == b'-': follow(y, x - 1, b'-+o') follow(y, x + 1, b'-+o') return result for y, line in enumerate(lines): for x, ch in enumerate(pycompat.bytestr(line)): if ch == b'#': # comment break if _isname(ch): edges[getname(y, x)] += parents(y, x) return dict(edges) class simplefilectx(object): def __init__(self, path, data): self._data = data self._path = path def data(self): return self._data def filenode(self): return None def path(self): return self._path def copysource(self): return None def flags(self): return b'' class simplecommitctx(context.committablectx): def __init__(self, repo, name, parentctxs, added): opts = { 'changes': scmutil.status([], list(added), [], [], [], [], []), 'date': b'0 0', 'extra': {b'branch': b'default'}, } super(simplecommitctx, self).__init__(repo, name, **opts) self._added = added self._parents = parentctxs while len(self._parents) < 2: self._parents.append(repo[repo.nullid]) def filectx(self, key): return simplefilectx(key, self._added[key]) def commit(self): return self._repo.commitctx(self) def p1copies(self): return {} def p2copies(self): return {} def _walkgraph(edges): """yield node, parents in topologically order""" visible = set(edges.keys()) remaining = {} # {str: [str]} for k, vs in edges.items(): for v in vs: if v not in remaining: remaining[v] = [] remaining[k] = vs[:] while remaining: leafs = [k for k, v in remaining.items() if not v] if not leafs: raise error.Abort(_('the graph has cycles')) for leaf in sorted(leafs): if leaf in visible: yield leaf, edges[leaf] del remaining[leaf] for k, v in remaining.items(): if leaf in v: v.remove(leaf) def _getcomments(text): r""" >>> [pycompat.sysstr(s) for s in _getcomments(br''' ... G ... | ... I D C F # split: B -> E, F, G ... \ \| | # replace: C -> D -> H ... H B E # prune: F, I ... \|/ ... A ... ''')] ['split: B -> E, F, G', 'replace: C -> D -> H', 'prune: F, I'] """ for line in text.splitlines(): if b' # ' not in line: continue yield line.split(b' # ', 1)[1].split(b' # ')[0].strip() @command(b'debugdrawdag', []) def debugdrawdag(ui, repo, **opts): r"""read an ASCII graph from stdin and create changesets The ASCII graph is like what :hg:`log -G` outputs, with each `o` replaced to the name of the node. The command will create dummy changesets and local tags with those names to make the dummy changesets easier to be referred to. If the name of a node is a single character 'o', It will be replaced by the word to the right. This makes it easier to reuse :hg:`log -G -T '{desc}'` outputs. For root (no parents) nodes, revset can be used to query existing repo. Note that the revset cannot have confusing characters which can be seen as the part of the graph edges, like `|/+-\`. """ text = ui.fin.read() # parse the graph and make sure len(parents) <= 2 for each node edges = _parseasciigraph(text) for k, v in edges.items(): if len(v) > 2: raise error.Abort(_('%s: too many parents: %s') % (k, b' '.join(v))) # parse comments to get extra file content instructions files = collections.defaultdict(dict) # {(name, path): content} comments = list(_getcomments(text)) filere = re.compile(br'^(\w+)/([\w/]+)\s*=\s*(.*)$', re.M) for name, path, content in filere.findall(b'\n'.join(comments)): content = content.replace(br'\n', b'\n').replace(br'\1', b'\1') files[name][path] = content committed = {None: repo.nullid} # {name: node} # for leaf nodes, try to find existing nodes in repo for name, parents in edges.items(): if len(parents) == 0: try: committed[name] = scmutil.revsingle(repo, name) except error.RepoLookupError: pass # commit in topological order for name, parents in _walkgraph(edges): if name in committed: continue pctxs = [repo[committed[n]] for n in parents] pctxs.sort(key=lambda c: c.node()) added = {} if len(parents) > 1: # If it's a merge, take the files and contents from the parents for f in pctxs[1].manifest(): if f not in pctxs[0].manifest(): added[f] = pctxs[1][f].data() else: # If it's not a merge, add a single file added[name] = name # add extra file contents in comments for path, content in files.get(name, {}).items(): added[path] = content ctx = simplecommitctx(repo, name, pctxs, added) n = ctx.commit() committed[name] = n tagsmod.tag( repo, [name], n, message=None, user=None, date=None, local=True ) # handle special comments with repo.wlock(), repo.lock(), repo.transaction(b'drawdag'): getctx = lambda x: repo.unfiltered()[committed[x.strip()]] for comment in comments: rels = [] # obsolete relationships args = comment.split(b':', 1) if len(args) <= 1: continue cmd = args[0].strip() arg = args[1].strip() if cmd in (b'replace', b'rebase', b'amend'): nodes = [getctx(m) for m in arg.split(b'->')] for i in range(len(nodes) - 1): rels.append(((nodes[i],), (nodes[i + 1],))) elif cmd in (b'split',): pre, succs = arg.split(b'->') succs = succs.split(b',') rels.append(((getctx(pre),), (getctx(s) for s in succs))) elif cmd in (b'prune',): for n in arg.split(b','): rels.append(((getctx(n),), ())) if rels: obsolete.createmarkers(repo, rels, date=(0, 0), operation=cmd)