filemerge: add support for partial conflict resolution by external tool
A common class of merge conflicts is in imports/#includes/etc. It's
relatively easy to write a tool that can resolve these conflicts,
perhaps by naively just unioning the statements and leaving any
cleanup to other tools to do later [1]. Such specialized tools cannot
generally resolve all conflicts in a file, of course. Let's therefore
call them "partial merge tools". Note that the internal simplemerge
algorithm is such a partial merge tool - one that only resolves
trivial "conflicts" where one side is unchanged or both sides change
in the same way.
One can also imagine having smarter language-aware partial tools that
merge the AST. It may be useful for such tools to interactively let
the user resolve any conflicts it can't resolve itself. However,
having the option of implementing it as a partial merge tool means
that the developer doesn't *need* to create a UI for it. Instead, the
user can resolve any remaining conflicts with their regular merge tool
(e.g. `:merge3` or `meld).
We don't currently have a way to let the user define such partial
merge tools. That's what this patch addresses. It lets the user
configure partial merge tools to run. Each tool can be configured to
run only on files matching certain patterns (e.g. "*.py"). The tool
takes three inputs (local, base, other) and resolves conflicts by
updating these in place. For example, let's say the inputs are these:
base:
```
import sys
def main():
print('Hello')
```
local:
```
import os
import sys
def main():
print('Hi')
```
other:
```
import re
import sys
def main():
print('Howdy')
```
A partial merge tool could now resolve the conflicting imports by
replacing the import statements in *all* files by the following
snippet, while leaving the remainder of the files unchanged.
```
import os
import re
import sys
```
As a result, simplemerge and any regular merge tool that runs after
the partial merge tool(s) will consider the imports to be
non-conflicting and will only present the conflict in `main()` to the
user.
Differential Revision: https://phab.mercurial-scm.org/D12356
# upgrade.py - functions for in place upgrade of Mercurial repository
#
# Copyright (c) 2016-present, Gregory Szorc
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from .i18n import _
from . import (
error,
hg,
localrepo,
lock as lockmod,
pycompat,
requirements as requirementsmod,
scmutil,
)
from .upgrade_utils import (
actions as upgrade_actions,
engine as upgrade_engine,
)
from .utils import (
stringutil,
)
allformatvariant = upgrade_actions.allformatvariant
def upgraderepo(
ui,
repo,
run=False,
optimize=None,
backup=True,
manifest=None,
changelog=None,
filelogs=None,
):
"""Upgrade a repository in place."""
if optimize is None:
optimize = set()
repo = repo.unfiltered()
specified_revlogs = {}
if changelog is not None:
specified_revlogs[upgrade_engine.UPGRADE_CHANGELOG] = changelog
if manifest is not None:
specified_revlogs[upgrade_engine.UPGRADE_MANIFEST] = manifest
if filelogs is not None:
specified_revlogs[upgrade_engine.UPGRADE_FILELOGS] = filelogs
# Ensure the repository can be upgraded.
upgrade_actions.check_source_requirements(repo)
default_options = localrepo.defaultcreateopts(repo.ui)
newreqs = localrepo.newreporequirements(repo.ui, default_options)
newreqs.update(upgrade_actions.preservedrequirements(repo))
upgrade_actions.check_requirements_changes(repo, newreqs)
# Find and validate all improvements that can be made.
alloptimizations = upgrade_actions.findoptimizations(repo)
# Apply and Validate arguments.
optimizations = []
for o in alloptimizations:
if o.name in optimize:
optimizations.append(o)
optimize.discard(o.name)
if optimize: # anything left is unknown
raise error.Abort(
_(b'unknown optimization action requested: %s')
% b', '.join(sorted(optimize)),
hint=_(b'run without arguments to see valid optimizations'),
)
format_upgrades = upgrade_actions.find_format_upgrades(repo)
up_actions = upgrade_actions.determine_upgrade_actions(
repo, format_upgrades, optimizations, repo.requirements, newreqs
)
removed_actions = upgrade_actions.find_format_downgrades(repo)
# check if we need to touch revlog and if so, which ones
touched_revlogs = set()
overwrite_msg = _(b'warning: ignoring %14s, as upgrade is changing: %s\n')
select_msg = _(b'note: selecting %s for processing to change: %s\n')
msg_issued = 0
FL = upgrade_engine.UPGRADE_FILELOGS
MN = upgrade_engine.UPGRADE_MANIFEST
CL = upgrade_engine.UPGRADE_CHANGELOG
if optimizations:
if any(specified_revlogs.values()):
# we have some limitation on revlogs to be recloned
for rl, enabled in specified_revlogs.items():
if enabled:
touched_revlogs.add(rl)
else:
touched_revlogs = set(upgrade_engine.UPGRADE_ALL_REVLOGS)
for rl, enabled in specified_revlogs.items():
if not enabled:
touched_revlogs.discard(rl)
if repo.shared():
unsafe_actions = set()
unsafe_actions.update(up_actions)
unsafe_actions.update(removed_actions)
unsafe_actions.update(optimizations)
unsafe_actions = [
a for a in unsafe_actions if not a.compatible_with_share
]
unsafe_actions.sort(key=lambda a: a.name)
if unsafe_actions:
m = _(b'cannot use these actions on a share repository: %s')
h = _(b'upgrade the main repository directly')
actions = b', '.join(a.name for a in unsafe_actions)
m %= actions
raise error.Abort(m, hint=h)
for action in sorted(up_actions + removed_actions, key=lambda a: a.name):
# optimisation does not "requires anything, they just needs it.
if action.type != upgrade_actions.FORMAT_VARIANT:
continue
if action.touches_filelogs and FL not in touched_revlogs:
if FL in specified_revlogs:
if not specified_revlogs[FL]:
msg = overwrite_msg % (b'--no-filelogs', action.name)
ui.warn(msg)
msg_issued = 2
else:
msg = select_msg % (b'all-filelogs', action.name)
ui.status(msg)
if not ui.quiet:
msg_issued = 1
touched_revlogs.add(FL)
if action.touches_manifests and MN not in touched_revlogs:
if MN in specified_revlogs:
if not specified_revlogs[MN]:
msg = overwrite_msg % (b'--no-manifest', action.name)
ui.warn(msg)
msg_issued = 2
else:
msg = select_msg % (b'all-manifestlogs', action.name)
ui.status(msg)
if not ui.quiet:
msg_issued = 1
touched_revlogs.add(MN)
if action.touches_changelog and CL not in touched_revlogs:
if CL in specified_revlogs:
if not specified_revlogs[CL]:
msg = overwrite_msg % (b'--no-changelog', action.name)
ui.warn(msg)
msg_issued = True
else:
msg = select_msg % (b'changelog', action.name)
ui.status(msg)
if not ui.quiet:
msg_issued = 1
touched_revlogs.add(CL)
if msg_issued >= 2:
ui.warn((b"\n"))
elif msg_issued >= 1:
ui.status((b"\n"))
upgrade_op = upgrade_actions.UpgradeOperation(
ui,
newreqs,
repo.requirements,
up_actions,
removed_actions,
touched_revlogs,
backup,
)
if not run:
fromconfig = []
onlydefault = []
for d in format_upgrades:
if d.fromconfig(repo):
fromconfig.append(d)
elif d.default:
onlydefault.append(d)
if fromconfig or onlydefault:
if fromconfig:
ui.status(
_(
b'repository lacks features recommended by '
b'current config options:\n\n'
)
)
for i in fromconfig:
ui.status(b'%s\n %s\n\n' % (i.name, i.description))
if onlydefault:
ui.status(
_(
b'repository lacks features used by the default '
b'config options:\n\n'
)
)
for i in onlydefault:
ui.status(b'%s\n %s\n\n' % (i.name, i.description))
ui.status(b'\n')
else:
ui.status(_(b'(no format upgrades found in existing repository)\n'))
ui.status(
_(
b'performing an upgrade with "--run" will make the following '
b'changes:\n\n'
)
)
upgrade_op.print_requirements()
upgrade_op.print_optimisations()
upgrade_op.print_upgrade_actions()
upgrade_op.print_affected_revlogs()
if upgrade_op.unused_optimizations:
ui.status(
_(
b'additional optimizations are available by specifying '
b'"--optimize <name>":\n\n'
)
)
upgrade_op.print_unused_optimizations()
return
if not (upgrade_op.upgrade_actions or upgrade_op.removed_actions):
ui.status(_(b'nothing to do\n'))
return
# Else we're in the run=true case.
ui.write(_(b'upgrade will perform the following actions:\n\n'))
upgrade_op.print_requirements()
upgrade_op.print_optimisations()
upgrade_op.print_upgrade_actions()
upgrade_op.print_affected_revlogs()
ui.status(_(b'beginning upgrade...\n'))
with repo.wlock(), repo.lock():
ui.status(_(b'repository locked and read-only\n'))
# Our strategy for upgrading the repository is to create a new,
# temporary repository, write data to it, then do a swap of the
# data. There are less heavyweight ways to do this, but it is easier
# to create a new repo object than to instantiate all the components
# (like the store) separately.
tmppath = pycompat.mkdtemp(prefix=b'upgrade.', dir=repo.path)
backuppath = None
try:
ui.status(
_(
b'creating temporary repository to stage upgraded '
b'data: %s\n'
)
% tmppath
)
# clone ui without using ui.copy because repo.ui is protected
repoui = repo.ui.__class__(repo.ui)
dstrepo = hg.repository(repoui, path=tmppath, create=True)
with dstrepo.wlock(), dstrepo.lock():
backuppath = upgrade_engine.upgrade(
ui, repo, dstrepo, upgrade_op
)
finally:
ui.status(_(b'removing temporary repository %s\n') % tmppath)
repo.vfs.rmtree(tmppath, forcibly=True)
if backuppath and not ui.quiet:
ui.warn(
_(b'copy of old repository backed up at %s\n') % backuppath
)
ui.warn(
_(
b'the old repository will not be deleted; remove '
b'it to free up disk space once the upgraded '
b'repository is verified\n'
)
)
upgrade_op.print_post_op_messages()
def upgrade_share_to_safe(
ui,
hgvfs,
storevfs,
current_requirements,
mismatch_config,
mismatch_warn,
):
"""Upgrades a share to use share-safe mechanism"""
wlock = None
store_requirements = localrepo._readrequires(storevfs, False)
original_crequirements = current_requirements.copy()
# after upgrade, store requires will be shared, so lets find
# the requirements which are not present in store and
# write them to share's .hg/requires
diffrequires = current_requirements - store_requirements
# add share-safe requirement as it will mark the share as share-safe
diffrequires.add(requirementsmod.SHARESAFE_REQUIREMENT)
current_requirements.add(requirementsmod.SHARESAFE_REQUIREMENT)
# in `allow` case, we don't try to upgrade, we just respect the source
# state, update requirements and continue
if mismatch_config == b'allow':
return
try:
wlock = lockmod.trylock(ui, hgvfs, b'wlock', 0, 0)
# some process might change the requirement in between, re-read
# and update current_requirements
locked_requirements = localrepo._readrequires(hgvfs, True)
if locked_requirements != original_crequirements:
removed = current_requirements - locked_requirements
# update current_requirements in place because it's passed
# as reference
current_requirements -= removed
current_requirements |= locked_requirements
diffrequires = current_requirements - store_requirements
# add share-safe requirement as it will mark the share as share-safe
diffrequires.add(requirementsmod.SHARESAFE_REQUIREMENT)
current_requirements.add(requirementsmod.SHARESAFE_REQUIREMENT)
scmutil.writerequires(hgvfs, diffrequires)
ui.warn(_(b'repository upgraded to use share-safe mode\n'))
except error.LockError as e:
hint = _(
b"see `hg help config.format.use-share-safe` for more information"
)
if mismatch_config == b'upgrade-abort':
raise error.Abort(
_(b'failed to upgrade share, got error: %s')
% stringutil.forcebytestr(e.strerror),
hint=hint,
)
elif mismatch_warn:
ui.warn(
_(b'failed to upgrade share, got error: %s\n')
% stringutil.forcebytestr(e.strerror),
hint=hint,
)
finally:
if wlock:
wlock.release()
def downgrade_share_to_non_safe(
ui,
hgvfs,
sharedvfs,
current_requirements,
mismatch_config,
mismatch_warn,
):
"""Downgrades a share which use share-safe to not use it"""
wlock = None
source_requirements = localrepo._readrequires(sharedvfs, True)
original_crequirements = current_requirements.copy()
# we cannot be 100% sure on which requirements were present in store when
# the source supported share-safe. However, we do know that working
# directory requirements were not there. Hence we remove them
source_requirements -= requirementsmod.WORKING_DIR_REQUIREMENTS
current_requirements |= source_requirements
current_requirements.remove(requirementsmod.SHARESAFE_REQUIREMENT)
if mismatch_config == b'allow':
return
try:
wlock = lockmod.trylock(ui, hgvfs, b'wlock', 0, 0)
# some process might change the requirement in between, re-read
# and update current_requirements
locked_requirements = localrepo._readrequires(hgvfs, True)
if locked_requirements != original_crequirements:
removed = current_requirements - locked_requirements
# update current_requirements in place because it's passed
# as reference
current_requirements -= removed
current_requirements |= locked_requirements
current_requirements |= source_requirements
current_requirements -= set(requirementsmod.SHARESAFE_REQUIREMENT)
scmutil.writerequires(hgvfs, current_requirements)
ui.warn(_(b'repository downgraded to not use share-safe mode\n'))
except error.LockError as e:
hint = _(
b"see `hg help config.format.use-share-safe` for more information"
)
# If upgrade-abort is set, abort when upgrade fails, else let the
# process continue as `upgrade-allow` is set
if mismatch_config == b'downgrade-abort':
raise error.Abort(
_(b'failed to downgrade share, got error: %s')
% stringutil.forcebytestr(e.strerror),
hint=hint,
)
elif mismatch_warn:
ui.warn(
_(b'failed to downgrade share, got error: %s\n')
% stringutil.forcebytestr(e.strerror),
hint=hint,
)
finally:
if wlock:
wlock.release()