sparse: vendor Facebook-developed extension

Facebook has developed an extension to enable "sparse" checkouts -
a working directory with a subset of files. This feature is a critical
component in enabling repositories to scale to infinite number of
files while retaining reasonable performance. It's worth noting
that sparse checkout is only one possible solution to this problem:
another is virtual filesystems that realize files on first access.
But given that virtual filesystems may not be accessible to all
users, sparse checkout is necessary as a fallback.

Per mailing list discussion at
https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-March/095868.html
we want to add sparse checkout to the Mercurial distribution via
roughly the following mechanism:

1. Vendor extension as-is with minimal modifications (this patch)
2. Refactor extension so it is more clearly experimental and inline
   with Mercurial practices
3. Move code from extension into core where possible
4. Drop experimental labeling and/or move feature into core
   after sign-off from narrow clone feature owners

This commit essentially copies the sparse extension and tests
from revision 71e0a2aeca92a4078fe1b8c76e32c88ff1929737 of the
https://bitbucket.org/facebook/hg-experimental repository.

A list of modifications made as part of vendoring is as follows:

* "EXPERIMENTAL" added to module docstring
* Imports were changed to match Mercurial style conventions
* "testedwith" value was updated to core Mercurial special value and
  comment boilerplate was inserted
* A "clone_sparse" function was renamed to "clonesparse" to appease
  the style checker
* Paths to the sparse extension in tests reflect built-in location
* test-sparse-extensions.t was renamed to test-sparse-fsmonitor.t
  and references to "simplecache" were removed. The test always skips
  because it isn't trivial to run it given the way we currently run
  fsmonitor tests
* A double empty line was removed from test-sparse-profiles.t

There are aspects of the added code that are obviously not ideal.
The goal is to make a minimal number of modifications as part of
the vendoring to make it easier to track changes from the original
implementation. Refactoring will occur in subsequent patches.

hgext/sparse.py

@@ -0,0 +1,1081 b''
+# sparse.py - allow sparse checkouts of the working directory
+#
+# Copyright 2014 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.
+
+"""allow sparse checkouts of the working directory (EXPERIMENTAL)
+"""
+
+from __future__ import absolute_import
+
+import collections
+import hashlib
+import os
+
+from mercurial.i18n import _
+from mercurial.node import nullid
+from mercurial import (
+    cmdutil,
+    commands,
+    context,
+    dirstate,
+    error,
+    extensions,
+    hg,
+    localrepo,
+    match as matchmod,
+    merge as mergemod,
+    registrar,
+    util,
+)
+
+# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
+# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
+# be specifying the version(s) of Mercurial they are tested with, or
+# leave the attribute unspecified.
+testedwith = 'ships-with-hg-core'
+
+cmdtable = {}
+command = registrar.command(cmdtable)
+
+def uisetup(ui):
+    _setupupdates(ui)
+    _setupcommit(ui)
+
+def extsetup(ui):
+    _setupclone(ui)
+    _setuplog(ui)
+    _setupadd(ui)
+    _setupdirstate(ui)
+    # if fsmonitor is enabled, tell it to use our hash function
+    try:
+        fsmonitor = extensions.find('fsmonitor')
+        def _hashignore(orig, ignore):
+            return _hashmatcher(ignore)
+        extensions.wrapfunction(fsmonitor, '_hashignore', _hashignore)
+    except KeyError:
+        pass
+    # do the same for hgwatchman, old name
+    try:
+        hgwatchman = extensions.find('hgwatchman')
+        def _hashignore(orig, ignore):
+            return _hashmatcher(ignore)
+        extensions.wrapfunction(hgwatchman, '_hashignore', _hashignore)
+    except KeyError:
+        pass
+
+def reposetup(ui, repo):
+    if not util.safehasattr(repo, 'dirstate'):
+        return
+
+    _wraprepo(ui, repo)
+
+def replacefilecache(cls, propname, replacement):
+    """Replace a filecache property with a new class. This allows changing the
+    cache invalidation condition."""
+    origcls = cls
+    assert callable(replacement)
+    while cls is not object:
+        if propname in cls.__dict__:
+            orig = cls.__dict__[propname]
+            setattr(cls, propname, replacement(orig))
+            break
+        cls = cls.__bases__[0]
+
+    if cls is object:
+        raise AttributeError(_("type '%s' has no property '%s'") % (origcls,
+                             propname))
+
+def _setupupdates(ui):
+    def _calculateupdates(orig, repo, wctx, mctx, ancestors, branchmerge, *arg,
+                          **kwargs):
+        """Filter updates to only lay out files that match the sparse rules.
+        """
+        actions, diverge, renamedelete = orig(repo, wctx, mctx, ancestors,
+                                              branchmerge, *arg, **kwargs)
+
+        if not util.safehasattr(repo, 'sparsematch'):
+            return actions, diverge, renamedelete
+
+        files = set()
+        prunedactions = {}
+        oldrevs = [pctx.rev() for pctx in wctx.parents()]
+        oldsparsematch = repo.sparsematch(*oldrevs)
+
+        if branchmerge:
+            # If we're merging, use the wctx filter, since we're merging into
+            # the wctx.
+            sparsematch = repo.sparsematch(wctx.parents()[0].rev())
+        else:
+            # If we're updating, use the target context's filter, since we're
+            # moving to the target context.
+            sparsematch = repo.sparsematch(mctx.rev())
+
+        temporaryfiles = []
+        for file, action in actions.iteritems():
+            type, args, msg = action
+            files.add(file)
+            if sparsematch(file):
+                prunedactions[file] = action
+            elif type == 'm':
+                temporaryfiles.append(file)
+                prunedactions[file] = action
+            elif branchmerge:
+                if type != 'k':
+                    temporaryfiles.append(file)
+                    prunedactions[file] = action
+            elif type == 'f':
+                prunedactions[file] = action
+            elif file in wctx:
+                prunedactions[file] = ('r', args, msg)
+
+        if len(temporaryfiles) > 0:
+            ui.status(_("temporarily included %d file(s) in the sparse checkout"
+                " for merging\n") % len(temporaryfiles))
+            repo.addtemporaryincludes(temporaryfiles)
+
+            # Add the new files to the working copy so they can be merged, etc
+            actions = []
+            message = 'temporarily adding to sparse checkout'
+            wctxmanifest = repo[None].manifest()
+            for file in temporaryfiles:
+                if file in wctxmanifest:
+                    fctx = repo[None][file]
+                    actions.append((file, (fctx.flags(), False), message))
+
+            typeactions = collections.defaultdict(list)
+            typeactions['g'] = actions
+            mergemod.applyupdates(repo, typeactions, repo[None], repo['.'],
+                                  False)
+
+            dirstate = repo.dirstate
+            for file, flags, msg in actions:
+                dirstate.normal(file)
+
+        profiles = repo.getactiveprofiles()
+        changedprofiles = profiles & files
+        # If an active profile changed during the update, refresh the checkout.
+        # Don't do this during a branch merge, since all incoming changes should
+        # have been handled by the temporary includes above.
+        if changedprofiles and not branchmerge:
+            mf = mctx.manifest()
+            for file in mf:
+                old = oldsparsematch(file)
+                new = sparsematch(file)
+                if not old and new:
+                    flags = mf.flags(file)
+                    prunedactions[file] = ('g', (flags, False), '')
+                elif old and not new:
+                    prunedactions[file] = ('r', [], '')
+
+        return prunedactions, diverge, renamedelete
+
+    extensions.wrapfunction(mergemod, 'calculateupdates', _calculateupdates)
+
+    def _update(orig, repo, node, branchmerge, *args, **kwargs):
+        results = orig(repo, node, branchmerge, *args, **kwargs)
+
+        # If we're updating to a location, clean up any stale temporary includes
+        # (ex: this happens during hg rebase --abort).
+        if not branchmerge and util.safehasattr(repo, 'sparsematch'):
+            repo.prunetemporaryincludes()
+        return results
+
+    extensions.wrapfunction(mergemod, 'update', _update)
+
+def _setupcommit(ui):
+    def _refreshoncommit(orig, self, node):
+        """Refresh the checkout when commits touch .hgsparse
+        """
+        orig(self, node)
+        repo = self._repo
+        if util.safehasattr(repo, 'getsparsepatterns'):
+            ctx = repo[node]
+            _, _, profiles = repo.getsparsepatterns(ctx.rev())
+            if set(profiles) & set(ctx.files()):
+                origstatus = repo.status()
+                origsparsematch = repo.sparsematch()
+                _refresh(repo.ui, repo, origstatus, origsparsematch, True)
+
+            repo.prunetemporaryincludes()
+
+    extensions.wrapfunction(context.committablectx, 'markcommitted',
+        _refreshoncommit)
+
+def _setuplog(ui):
+    entry = commands.table['^log|history']
+    entry[1].append(('', 'sparse', None,
+        "limit to changesets affecting the sparse checkout"))
+
+    def _logrevs(orig, repo, opts):
+        revs = orig(repo, opts)
+        if opts.get('sparse'):
+            sparsematch = repo.sparsematch()
+            def ctxmatch(rev):
+                ctx = repo[rev]
+                return any(f for f in ctx.files() if sparsematch(f))
+            revs = revs.filter(ctxmatch)
+        return revs
+    extensions.wrapfunction(cmdutil, '_logrevs', _logrevs)
+
+def _clonesparsecmd(orig, ui, repo, *args, **opts):
+    include_pat = opts.get('include')
+    exclude_pat = opts.get('exclude')
+    enableprofile_pat = opts.get('enable_profile')
+    include = exclude = enableprofile = False
+    if include_pat:
+        pat = include_pat
+        include = True
+    if exclude_pat:
+        pat = exclude_pat
+        exclude = True
+    if enableprofile_pat:
+        pat = enableprofile_pat
+        enableprofile = True
+    if sum([include, exclude, enableprofile]) > 1:
+        raise error.Abort(_("too many flags specified."))
+    if include or exclude or enableprofile:
+        def clonesparse(orig, self, node, overwrite, *args, **kwargs):
+            _config(self.ui, self.unfiltered(), pat, {}, include=include,
+                    exclude=exclude, enableprofile=enableprofile)
+            return orig(self, node, overwrite, *args, **kwargs)
+        extensions.wrapfunction(hg, 'updaterepo', clonesparse)
+    return orig(ui, repo, *args, **opts)
+
+def _setupclone(ui):
+    entry = commands.table['^clone']
+    entry[1].append(('', 'enable-profile', [],
+                    'enable a sparse profile'))
+    entry[1].append(('', 'include', [],
+                    'include sparse pattern'))
+    entry[1].append(('', 'exclude', [],
+                    'exclude sparse pattern'))
+    extensions.wrapcommand(commands.table, 'clone', _clonesparsecmd)
+
+def _setupadd(ui):
+    entry = commands.table['^add']
+    entry[1].append(('s', 'sparse', None,
+                    'also include directories of added files in sparse config'))
+
+    def _add(orig, ui, repo, *pats, **opts):
+        if opts.get('sparse'):
+            dirs = set()
+            for pat in pats:
+                dirname, basename = util.split(pat)
+                dirs.add(dirname)
+            _config(ui, repo, list(dirs), opts, include=True)
+        return orig(ui, repo, *pats, **opts)
+
+    extensions.wrapcommand(commands.table, 'add', _add)
+
+def _setupdirstate(ui):
+    """Modify the dirstate to prevent stat'ing excluded files,
+    and to prevent modifications to files outside the checkout.
+    """
+
+    def _dirstate(orig, repo):
+        dirstate = orig(repo)
+        dirstate.repo = repo
+        return dirstate
+    extensions.wrapfunction(
+        localrepo.localrepository.dirstate, 'func', _dirstate)
+
+    # The atrocity below is needed to wrap dirstate._ignore. It is a cached
+    # property, which means normal function wrapping doesn't work.
+    class ignorewrapper(object):
+        def __init__(self, orig):
+            self.orig = orig
+            self.origignore = None
+            self.func = None
+            self.sparsematch = None
+
+        def __get__(self, obj, type=None):
+            repo = obj.repo
+            origignore = self.orig.__get__(obj)
+            if not util.safehasattr(repo, 'sparsematch'):
+                return origignore
+
+            sparsematch = repo.sparsematch()
+            if self.sparsematch != sparsematch or self.origignore != origignore:
+                self.func = unionmatcher([origignore,
+                                          negatematcher(sparsematch)])
+                self.sparsematch = sparsematch
+                self.origignore = origignore
+            return self.func
+
+        def __set__(self, obj, value):
+            return self.orig.__set__(obj, value)
+
+        def __delete__(self, obj):
+            return self.orig.__delete__(obj)
+
+    replacefilecache(dirstate.dirstate, '_ignore', ignorewrapper)
+
+    # dirstate.rebuild should not add non-matching files
+    def _rebuild(orig, self, parent, allfiles, changedfiles=None):
+        if util.safehasattr(self.repo, 'sparsematch'):
+            matcher = self.repo.sparsematch()
+            allfiles = allfiles.matches(matcher)
+            if changedfiles:
+                changedfiles = [f for f in changedfiles if matcher(f)]
+
+            if changedfiles is not None:
+                # In _rebuild, these files will be deleted from the dirstate
+                # when they are not found to be in allfiles
+                dirstatefilestoremove = set(f for f in self if not matcher(f))
+                changedfiles = dirstatefilestoremove.union(changedfiles)
+
+        return orig(self, parent, allfiles, changedfiles)
+    extensions.wrapfunction(dirstate.dirstate, 'rebuild', _rebuild)
+
+    # Prevent adding files that are outside the sparse checkout
+    editfuncs = ['normal', 'add', 'normallookup', 'copy', 'remove', 'merge']
+    hint = _('include file with `hg sparse --include <pattern>` or use ' +
+             '`hg add -s <file>` to include file directory while adding')
+    for func in editfuncs:
+        def _wrapper(orig, self, *args):
+            repo = self.repo
+            if util.safehasattr(repo, 'sparsematch'):
+                dirstate = repo.dirstate
+                sparsematch = repo.sparsematch()
+                for f in args:
+                    if (f is not None and not sparsematch(f) and
+                        f not in dirstate):
+                        raise error.Abort(_("cannot add '%s' - it is outside "
+                                            "the sparse checkout") % f,
+                                          hint=hint)
+            return orig(self, *args)
+        extensions.wrapfunction(dirstate.dirstate, func, _wrapper)
+
+def _wraprepo(ui, repo):
+    class SparseRepo(repo.__class__):
+        def readsparseconfig(self, raw):
+            """Takes a string sparse config and returns the includes,
+            excludes, and profiles it specified.
+            """
+            includes = set()
+            excludes = set()
+            current = includes
+            profiles = []
+            for line in raw.split('\n'):
+                line = line.strip()
+                if not line or line.startswith('#'):
+                    # empty or comment line, skip
+                    continue
+                elif line.startswith('%include '):
+                    line = line[9:].strip()
+                    if line:
+                        profiles.append(line)
+                elif line == '[include]':
+                    if current != includes:
+                        raise error.Abort(_('.hg/sparse cannot have includes ' +
+                            'after excludes'))
+                    continue
+                elif line == '[exclude]':
+                    current = excludes
+                elif line:
+                    if line.strip().startswith('/'):
+                        self.ui.warn(_('warning: sparse profile cannot use' +
+                                       ' paths starting with /, ignoring %s\n')
+                                       % line)
+                        continue
+                    current.add(line)
+
+            return includes, excludes, profiles
+
+        def getsparsepatterns(self, rev):
+            """Returns the include/exclude patterns specified by the
+            given rev.
+            """
+            if not self.vfs.exists('sparse'):
+                return set(), set(), []
+            if rev is None:
+                raise error.Abort(_("cannot parse sparse patterns from " +
+                    "working copy"))
+
+            raw = self.vfs.read('sparse')
+            includes, excludes, profiles = self.readsparseconfig(raw)
+
+            ctx = self[rev]
+            if profiles:
+                visited = set()
+                while profiles:
+                    profile = profiles.pop()
+                    if profile in visited:
+                        continue
+                    visited.add(profile)
+
+                    try:
+                        raw = self.getrawprofile(profile, rev)
+                    except error.ManifestLookupError:
+                        msg = (
+                            "warning: sparse profile '%s' not found "
+                            "in rev %s - ignoring it\n" % (profile, ctx))
+                        if self.ui.configbool(
+                                'sparse', 'missingwarning', True):
+                            self.ui.warn(msg)
+                        else:
+                            self.ui.debug(msg)
+                        continue
+                    pincludes, pexcludes, subprofs = \
+                        self.readsparseconfig(raw)
+                    includes.update(pincludes)
+                    excludes.update(pexcludes)
+                    for subprofile in subprofs:
+                        profiles.append(subprofile)
+
+                profiles = visited
+
+            if includes:
+                includes.add('.hg*')
+            return includes, excludes, profiles
+
+        def getrawprofile(self, profile, changeid):
+            try:
+                simplecache = extensions.find('simplecache')
+                node = self[changeid].hex()
+                def func():
+                    return self.filectx(profile, changeid=changeid).data()
+                key = 'sparseprofile:%s:%s' % (profile.replace('/', '__'), node)
+                return simplecache.memoize(func, key,
+                        simplecache.stringserializer, self.ui)
+            except KeyError:
+                return self.filectx(profile, changeid=changeid).data()
+
+        def sparsechecksum(self, filepath):
+            fh = open(filepath)
+            return hashlib.sha1(fh.read()).hexdigest()
+
+        def _sparsesignature(self, includetemp=True):
+            """Returns the signature string representing the contents of the
+            current project sparse configuration. This can be used to cache the
+            sparse matcher for a given set of revs."""
+            signaturecache = self.signaturecache
+            signature = signaturecache.get('signature')
+            if includetemp:
+                tempsignature = signaturecache.get('tempsignature')
+            else:
+                tempsignature = 0
+
+            if signature is None or (includetemp and tempsignature is None):
+                signature = 0
+                try:
+                    sparsepath = self.vfs.join('sparse')
+                    signature = self.sparsechecksum(sparsepath)
+                except (OSError, IOError):
+                    pass
+                signaturecache['signature'] = signature
+
+                tempsignature = 0
+                if includetemp:
+                    try:
+                        tempsparsepath = self.vfs.join('tempsparse')
+                        tempsignature = self.sparsechecksum(tempsparsepath)
+                    except (OSError, IOError):
+                        pass
+                    signaturecache['tempsignature'] = tempsignature
+            return '%s %s' % (str(signature), str(tempsignature))
+
+        def invalidatecaches(self):
+            self.invalidatesignaturecache()
+            return super(SparseRepo, self).invalidatecaches()
+
+        def invalidatesignaturecache(self):
+            self.signaturecache.clear()
+
+        def sparsematch(self, *revs, **kwargs):
+            """Returns the sparse match function for the given revs.
+
+            If multiple revs are specified, the match function is the union
+            of all the revs.
+
+            `includetemp` is used to indicate if the temporarily included file
+            should be part of the matcher.
+            """
+            if not revs or revs == (None,):
+                revs = [self.changelog.rev(node) for node in
+                    self.dirstate.parents() if node != nullid]
+
+            includetemp = kwargs.get('includetemp', True)
+            signature = self._sparsesignature(includetemp=includetemp)
+
+            key = '%s %s' % (str(signature), ' '.join([str(r) for r in revs]))
+
+            result = self.sparsecache.get(key, None)
+            if result:
+                return result
+
+            matchers = []
+            for rev in revs:
+                try:
+                    includes, excludes, profiles = self.getsparsepatterns(rev)
+
+                    if includes or excludes:
+                        # Explicitly include subdirectories of includes so
+                        # status will walk them down to the actual include.
+                        subdirs = set()
+                        for include in includes:
+                            dirname = os.path.dirname(include)
+                            # basename is used to avoid issues with absolute
+                            # paths (which on Windows can include the drive).
+                            while os.path.basename(dirname):
+                                subdirs.add(dirname)
+                                dirname = os.path.dirname(dirname)
+
+                        matcher = matchmod.match(self.root, '', [],
+                            include=includes, exclude=excludes,
+                            default='relpath')
+                        if subdirs:
+                            matcher = forceincludematcher(matcher, subdirs)
+                        matchers.append(matcher)
+                except IOError:
+                    pass
+
+            result = None
+            if not matchers:
+                result = matchmod.always(self.root, '')
+            elif len(matchers) == 1:
+                result = matchers[0]
+            else:
+                result = unionmatcher(matchers)
+
+            if kwargs.get('includetemp', True):
+                tempincludes = self.gettemporaryincludes()
+                result = forceincludematcher(result, tempincludes)
+
+            self.sparsecache[key] = result
+
+            return result
+
+        def getactiveprofiles(self):
+            revs = [self.changelog.rev(node) for node in
+                    self.dirstate.parents() if node != nullid]
+
+            activeprofiles = set()
+            for rev in revs:
+                _, _, profiles = self.getsparsepatterns(rev)
+                activeprofiles.update(profiles)
+
+            return activeprofiles
+
+        def writesparseconfig(self, include, exclude, profiles):
+            raw = '%s[include]\n%s\n[exclude]\n%s\n' % (
+                ''.join(['%%include %s\n' % p for p in sorted(profiles)]),
+                '\n'.join(sorted(include)),
+                '\n'.join(sorted(exclude)))
+            self.vfs.write("sparse", raw)
+            self.invalidatesignaturecache()
+
+        def addtemporaryincludes(self, files):
+            includes = self.gettemporaryincludes()
+            for file in files:
+                includes.add(file)
+            self._writetemporaryincludes(includes)
+
+        def gettemporaryincludes(self):
+            existingtemp = set()
+            if self.vfs.exists('tempsparse'):
+                raw = self.vfs.read('tempsparse')
+                existingtemp.update(raw.split('\n'))
+            return existingtemp
+
+        def _writetemporaryincludes(self, includes):
+            raw = '\n'.join(sorted(includes))
+            self.vfs.write('tempsparse', raw)
+            self.invalidatesignaturecache()
+
+        def prunetemporaryincludes(self):
+            if repo.vfs.exists('tempsparse'):
+                origstatus = self.status()
+                modified, added, removed, deleted, a, b, c = origstatus
+                if modified or added or removed or deleted:
+                    # Still have pending changes. Don't bother trying to prune.
+                    return
+
+                sparsematch = self.sparsematch(includetemp=False)
+                dirstate = self.dirstate
+                actions = []
+                dropped = []
+                tempincludes = self.gettemporaryincludes()
+                for file in tempincludes:
+                    if file in dirstate and not sparsematch(file):
+                        message = 'dropping temporarily included sparse files'
+                        actions.append((file, None, message))
+                        dropped.append(file)
+
+                typeactions = collections.defaultdict(list)
+                typeactions['r'] = actions
+                mergemod.applyupdates(self, typeactions, self[None], self['.'],
+                                      False)
+
+                # Fix dirstate
+                for file in dropped:
+                    dirstate.drop(file)
+
+                self.vfs.unlink('tempsparse')
+                self.invalidatesignaturecache()
+                msg = _("cleaned up %d temporarily added file(s) from the "
+                        "sparse checkout\n")
+                ui.status(msg % len(tempincludes))
+
+    if 'dirstate' in repo._filecache:
+        repo.dirstate.repo = repo
+    repo.sparsecache = {}
+    repo.signaturecache = {}
+    repo.__class__ = SparseRepo
+
+@command('^sparse', [
+    ('I', 'include', False, _('include files in the sparse checkout')),
+    ('X', 'exclude', False, _('exclude files in the sparse checkout')),
+    ('d', 'delete', False, _('delete an include/exclude rule')),
+    ('f', 'force', False, _('allow changing rules even with pending changes')),
+    ('', 'enable-profile', False, _('enables the specified profile')),
+    ('', 'disable-profile', False, _('disables the specified profile')),
+    ('', 'import-rules', False, _('imports rules from a file')),
+    ('', 'clear-rules', False, _('clears local include/exclude rules')),
+    ('', 'refresh', False, _('updates the working after sparseness changes')),
+    ('', 'reset', False, _('makes the repo full again')),
+    ] + commands.templateopts,
+    _('[--OPTION] PATTERN...'))
+def sparse(ui, repo, *pats, **opts):
+    """make the current checkout sparse, or edit the existing checkout
+
+    The sparse command is used to make the current checkout sparse.
+    This means files that don't meet the sparse condition will not be
+    written to disk, or show up in any working copy operations. It does
+    not affect files in history in any way.
+
+    Passing no arguments prints the currently applied sparse rules.
+
+    --include and --exclude are used to add and remove files from the sparse
+    checkout. The effects of adding an include or exclude rule are applied
+    immediately. If applying the new rule would cause a file with pending
+    changes to be added or removed, the command will fail. Pass --force to
+    force a rule change even with pending changes (the changes on disk will
+    be preserved).
+
+    --delete removes an existing include/exclude rule. The effects are
+    immediate.
+
+    --refresh refreshes the files on disk based on the sparse rules. This is
+    only necessary if .hg/sparse was changed by hand.
+
+    --enable-profile and --disable-profile accept a path to a .hgsparse file.
+    This allows defining sparse checkouts and tracking them inside the
+    repository. This is useful for defining commonly used sparse checkouts for
+    many people to use. As the profile definition changes over time, the sparse
+    checkout will automatically be updated appropriately, depending on which
+    changeset is checked out. Changes to .hgsparse are not applied until they
+    have been committed.
+
+    --import-rules accepts a path to a file containing rules in the .hgsparse
+    format, allowing you to add --include, --exclude and --enable-profile rules
+    in bulk. Like the --include, --exclude and --enable-profile switches, the
+    changes are applied immediately.
+
+    --clear-rules removes all local include and exclude rules, while leaving
+    any enabled profiles in place.
+
+    Returns 0 if editing the sparse checkout succeeds.
+    """
+    include = opts.get('include')
+    exclude = opts.get('exclude')
+    force = opts.get('force')
+    enableprofile = opts.get('enable_profile')
+    disableprofile = opts.get('disable_profile')
+    importrules = opts.get('import_rules')
+    clearrules = opts.get('clear_rules')
+    delete = opts.get('delete')
+    refresh = opts.get('refresh')
+    reset = opts.get('reset')
+    count = sum([include, exclude, enableprofile, disableprofile, delete,
+                 importrules, refresh, clearrules, reset])
+    if count > 1:
+        raise error.Abort(_("too many flags specified"))
+
+    if count == 0:
+        if repo.vfs.exists('sparse'):
+            ui.status(repo.vfs.read("sparse") + "\n")
+            temporaryincludes = repo.gettemporaryincludes()
+            if temporaryincludes:
+                ui.status(_("Temporarily Included Files (for merge/rebase):\n"))
+                ui.status(("\n".join(temporaryincludes) + "\n"))
+        else:
+            ui.status(_('repo is not sparse\n'))
+        return
+
+    if include or exclude or delete or reset or enableprofile or disableprofile:
+        _config(ui, repo, pats, opts, include=include, exclude=exclude,
+                reset=reset, delete=delete, enableprofile=enableprofile,
+                disableprofile=disableprofile, force=force)
+
+    if importrules:
+        _import(ui, repo, pats, opts, force=force)
+
+    if clearrules:
+        _clear(ui, repo, pats, force=force)
+
+    if refresh:
+        try:
+            wlock = repo.wlock()
+            fcounts = map(
+                len,
+                _refresh(ui, repo, repo.status(), repo.sparsematch(), force))
+            _verbose_output(ui, opts, 0, 0, 0, *fcounts)
+        finally:
+            wlock.release()
+
+def _config(ui, repo, pats, opts, include=False, exclude=False, reset=False,
+            delete=False, enableprofile=False, disableprofile=False,
+            force=False):
+    """
+    Perform a sparse config update. Only one of the kwargs may be specified.
+    """
+    wlock = repo.wlock()
+    try:
+        oldsparsematch = repo.sparsematch()
+
+        if repo.vfs.exists('sparse'):
+            raw = repo.vfs.read('sparse')
+            oldinclude, oldexclude, oldprofiles = map(
+                set, repo.readsparseconfig(raw))
+        else:
+            oldinclude = set()
+            oldexclude = set()
+            oldprofiles = set()
+
+        try:
+            if reset:
+                newinclude = set()
+                newexclude = set()
+                newprofiles = set()
+            else:
+                newinclude = set(oldinclude)
+                newexclude = set(oldexclude)
+                newprofiles = set(oldprofiles)
+
+            oldstatus = repo.status()
+
+            if any(pat.startswith('/') for pat in pats):
+                ui.warn(_('warning: paths cannot start with /, ignoring: %s\n')
+                          % ([pat for pat in pats if pat.startswith('/')]))
+            elif include:
+                newinclude.update(pats)
+            elif exclude:
+                newexclude.update(pats)
+            elif enableprofile:
+                newprofiles.update(pats)
+            elif disableprofile:
+                newprofiles.difference_update(pats)
+            elif delete:
+                newinclude.difference_update(pats)
+                newexclude.difference_update(pats)
+
+            repo.writesparseconfig(newinclude, newexclude, newprofiles)
+            fcounts = map(
+                len, _refresh(ui, repo, oldstatus, oldsparsematch, force))
+
+            profilecount = (len(newprofiles - oldprofiles) -
+                            len(oldprofiles - newprofiles))
+            includecount = (len(newinclude - oldinclude) -
+                            len(oldinclude - newinclude))
+            excludecount = (len(newexclude - oldexclude) -
+                            len(oldexclude - newexclude))
+            _verbose_output(
+                ui, opts, profilecount, includecount, excludecount, *fcounts)
+        except Exception:
+            repo.writesparseconfig(oldinclude, oldexclude, oldprofiles)
+            raise
+    finally:
+        wlock.release()
+
+def _import(ui, repo, files, opts, force=False):
+    with repo.wlock():
+        # load union of current active profile
+        revs = [repo.changelog.rev(node) for node in
+                repo.dirstate.parents() if node != nullid]
+
+        # read current configuration
+        raw = ''
+        if repo.vfs.exists('sparse'):
+            raw = repo.vfs.read('sparse')
+        oincludes, oexcludes, oprofiles = repo.readsparseconfig(raw)
+        includes, excludes, profiles = map(
+                set, (oincludes, oexcludes, oprofiles))
+
+        # all active rules
+        aincludes, aexcludes, aprofiles = set(), set(), set()
+        for rev in revs:
+            rincludes, rexcludes, rprofiles = repo.getsparsepatterns(rev)
+            aincludes.update(rincludes)
+            aexcludes.update(rexcludes)
+            aprofiles.update(rprofiles)
+
+        # import rules on top; only take in rules that are not yet
+        # part of the active rules.
+        changed = False
+        for file in files:
+            with util.posixfile(util.expandpath(file)) as importfile:
+                iincludes, iexcludes, iprofiles = repo.readsparseconfig(
+                    importfile.read())
+                oldsize = len(includes) + len(excludes) + len(profiles)
+                includes.update(iincludes - aincludes)
+                excludes.update(iexcludes - aexcludes)
+                profiles.update(set(iprofiles) - aprofiles)
+                if len(includes) + len(excludes) + len(profiles) > oldsize:
+                    changed = True
+
+        profilecount = includecount = excludecount = 0
+        fcounts = (0, 0, 0)
+
+        if changed:
+            profilecount = len(profiles - aprofiles)
+            includecount = len(includes - aincludes)
+            excludecount = len(excludes - aexcludes)
+
+            oldstatus = repo.status()
+            oldsparsematch = repo.sparsematch()
+            repo.writesparseconfig(includes, excludes, profiles)
+
+            try:
+                fcounts = map(
+                    len, _refresh(ui, repo, oldstatus, oldsparsematch, force))
+            except Exception:
+                repo.writesparseconfig(oincludes, oexcludes, oprofiles)
+                raise
+
+        _verbose_output(ui, opts, profilecount, includecount, excludecount,
+                        *fcounts)
+
+def _clear(ui, repo, files, force=False):
+    with repo.wlock():
+        raw = ''
+        if repo.vfs.exists('sparse'):
+            raw = repo.vfs.read('sparse')
+        includes, excludes, profiles = repo.readsparseconfig(raw)
+
+        if includes or excludes:
+            oldstatus = repo.status()
+            oldsparsematch = repo.sparsematch()
+            repo.writesparseconfig(set(), set(), profiles)
+            _refresh(ui, repo, oldstatus, oldsparsematch, force)
+
+def _refresh(ui, repo, origstatus, origsparsematch, force):
+    """Refreshes which files are on disk by comparing the old status and
+    sparsematch with the new sparsematch.
+
+    Will raise an exception if a file with pending changes is being excluded
+    or included (unless force=True).
+    """
+    modified, added, removed, deleted, unknown, ignored, clean = origstatus
+
+    # Verify there are no pending changes
+    pending = set()
+    pending.update(modified)
+    pending.update(added)
+    pending.update(removed)
+    sparsematch = repo.sparsematch()
+    abort = False
+    for file in pending:
+        if not sparsematch(file):
+            ui.warn(_("pending changes to '%s'\n") % file)
+            abort = not force
+    if abort:
+        raise error.Abort(_("could not update sparseness due to " +
+            "pending changes"))
+
+    # Calculate actions
+    dirstate = repo.dirstate
+    ctx = repo['.']
+    added = []
+    lookup = []
+    dropped = []
+    mf = ctx.manifest()
+    files = set(mf)
+
+    actions = {}
+
+    for file in files:
+        old = origsparsematch(file)
+        new = sparsematch(file)
+        # Add files that are newly included, or that don't exist in
+        # the dirstate yet.
+        if (new and not old) or (old and new and not file in dirstate):
+            fl = mf.flags(file)
+            if repo.wvfs.exists(file):
+                actions[file] = ('e', (fl,), '')
+                lookup.append(file)
+            else:
+                actions[file] = ('g', (fl, False), '')
+                added.append(file)
+        # Drop files that are newly excluded, or that still exist in
+        # the dirstate.
+        elif (old and not new) or (not old and not new and file in dirstate):
+            dropped.append(file)
+            if file not in pending:
+                actions[file] = ('r', [], '')
+
+    # Verify there are no pending changes in newly included files
+    abort = False
+    for file in lookup:
+        ui.warn(_("pending changes to '%s'\n") % file)
+        abort = not force
+    if abort:
+        raise error.Abort(_("cannot change sparseness due to " +
+            "pending changes (delete the files or use --force " +
+            "to bring them back dirty)"))
+
+    # Check for files that were only in the dirstate.
+    for file, state in dirstate.iteritems():
+        if not file in files:
+            old = origsparsematch(file)
+            new = sparsematch(file)
+            if old and not new:
+                dropped.append(file)
+
+    # Apply changes to disk
+    typeactions = dict((m, []) for m in 'a f g am cd dc r dm dg m e k'.split())
+    for f, (m, args, msg) in actions.iteritems():
+        if m not in typeactions:
+            typeactions[m] = []
+        typeactions[m].append((f, args, msg))
+    mergemod.applyupdates(repo, typeactions, repo[None], repo['.'], False)
+
+    # Fix dirstate
+    for file in added:
+        dirstate.normal(file)
+
+    for file in dropped:
+        dirstate.drop(file)
+
+    for file in lookup:
+        # File exists on disk, and we're bringing it back in an unknown state.
+        dirstate.normallookup(file)
+
+    return added, dropped, lookup
+
+def _verbose_output(ui, opts, profilecount, includecount, excludecount, added,
+                    dropped, lookup):
+    """Produce --verbose and templatable output
+
+    This specifically enables -Tjson, providing machine-readable stats on how
+    the sparse profile changed.
+
+    """
+    with ui.formatter('sparse', opts) as fm:
+        fm.startitem()
+        fm.condwrite(ui.verbose, 'profiles_added', 'Profile # change: %d\n',
+                     profilecount)
+        fm.condwrite(ui.verbose, 'include_rules_added',
+                     'Include rule # change: %d\n', includecount)
+        fm.condwrite(ui.verbose, 'exclude_rules_added',
+                     'Exclude rule # change: %d\n', excludecount)
+        # In 'plain' verbose mode, mergemod.applyupdates already outputs what
+        # files are added or removed outside of the templating formatter
+        # framework. No point in repeating ourselves in that case.
+        if not fm.isplain():
+            fm.condwrite(ui.verbose, 'files_added', 'Files added: %d\n',
+                         added)
+            fm.condwrite(ui.verbose, 'files_dropped', 'Files dropped: %d\n',
+                         dropped)
+            fm.condwrite(ui.verbose, 'files_conflicting',
+                         'Files conflicting: %d\n', lookup)
+
+class forceincludematcher(object):
+    """A matcher that returns true for any of the forced includes before testing
+    against the actual matcher."""
+    def __init__(self, matcher, includes):
+        self._matcher = matcher
+        self._includes = includes
+
+    def __call__(self, value):
+        return value in self._includes or self._matcher(value)
+
+    def always(self):
+        return False
+
+    def files(self):
+        return []
+
+    def isexact(self):
+        return False
+
+    def anypats(self):
+        return True
+
+    def prefix(self):
+        return False
+
+    def hash(self):
+        sha1 = hashlib.sha1()
+        sha1.update(_hashmatcher(self._matcher))
+        for include in sorted(self._includes):
+            sha1.update(include + '\0')
+        return sha1.hexdigest()
+
+class unionmatcher(object):
+    """A matcher that is the union of several matchers."""
+    def __init__(self, matchers):
+        self._matchers = matchers
+
+    def __call__(self, value):
+        for match in self._matchers:
+            if match(value):
+                return True
+        return False
+
+    def always(self):
+        return False
+
+    def files(self):
+        return []
+
+    def isexact(self):
+        return False
+
+    def anypats(self):
+        return True
+
+    def prefix(self):
+        return False
+
+    def hash(self):
+        sha1 = hashlib.sha1()
+        for m in self._matchers:
+            sha1.update(_hashmatcher(m))
+        return sha1.hexdigest()
+
+class negatematcher(object):
+    def __init__(self, matcher):
+        self._matcher = matcher
+
+    def __call__(self, value):
+        return not self._matcher(value)
+
+    def always(self):
+        return False
+
+    def files(self):
+        return []
+
+    def isexact(self):
+        return False
+
+    def anypats(self):
+        return True
+
+    def hash(self):
+        sha1 = hashlib.sha1()
+        sha1.update('negate')
+        sha1.update(_hashmatcher(self._matcher))
+        return sha1.hexdigest()
+
+def _hashmatcher(matcher):
+    if util.safehasattr(matcher, 'hash'):
+        return matcher.hash()
+
+    sha1 = hashlib.sha1()
+    sha1.update(repr(matcher))
+    return sha1.hexdigest()

tests/test-sparse-clear.t

@@ -0,0 +1,73 b''
+test sparse
+
+  $ hg init myrepo
+  $ cd myrepo
+  $ cat >> $HGRCPATH <<EOF
+  > [extensions]
+  > sparse=
+  > purge=
+  > strip=
+  > rebase=
+  > EOF
+
+  $ echo a > index.html
+  $ echo x > data.py
+  $ echo z > readme.txt
+  $ cat > base.sparse <<EOF
+  > [include]
+  > *.sparse
+  > EOF
+  $ hg ci -Aqm 'initial'
+  $ cat > webpage.sparse <<EOF
+  > %include base.sparse
+  > [include]
+  > *.html
+  > EOF
+  $ hg ci -Aqm 'initial'
+
+Clear rules when there are includes
+
+  $ hg sparse --include *.py
+  $ ls
+  data.py
+  $ hg sparse --clear-rules
+  $ ls
+  base.sparse
+  data.py
+  index.html
+  readme.txt
+  webpage.sparse
+
+Clear rules when there are excludes
+
+  $ hg sparse --exclude *.sparse
+  $ ls
+  data.py
+  index.html
+  readme.txt
+  $ hg sparse --clear-rules
+  $ ls
+  base.sparse
+  data.py
+  index.html
+  readme.txt
+  webpage.sparse
+
+Clearing rules should not alter profiles
+
+  $ hg sparse --enable-profile webpage.sparse
+  $ ls
+  base.sparse
+  index.html
+  webpage.sparse
+  $ hg sparse --include *.py
+  $ ls
+  base.sparse
+  data.py
+  index.html
+  webpage.sparse
+  $ hg sparse --clear-rules
+  $ ls
+  base.sparse
+  index.html
+  webpage.sparse

tests/test-sparse-clone.t

@@ -0,0 +1,72 b''
+test sparse
+
+  $ cat >> $HGRCPATH << EOF
+  > [ui]
+  > ssh = python "$RUNTESTDIR/dummyssh"
+  > username = nobody <[e-mail]>
+  > [extensions]
+  > sparse=
+  > purge=
+  > strip=
+  > rebase=
+  > EOF
+
+  $ hg init myrepo
+  $ cd myrepo
+  $ echo a > index.html
+  $ echo x > data.py
+  $ echo z > readme.txt
+  $ cat > webpage.sparse <<EOF
+  > [include]
+  > *.html
+  > EOF
+  $ cat > backend.sparse <<EOF
+  > [include]
+  > *.py
+  > EOF
+  $ hg ci -Aqm 'initial'
+  $ cd ..
+
+Verify local clone with a sparse profile works
+
+  $ hg clone --enable-profile webpage.sparse myrepo clone1
+  updating to branch default
+  warning: sparse profile 'webpage.sparse' not found in rev 000000000000 - ignoring it
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ cd clone1
+  $ ls
+  index.html
+  $ cd ..
+
+Verify local clone with include works
+
+  $ hg clone --include *.sparse myrepo clone2
+  updating to branch default
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ cd clone2
+  $ ls
+  backend.sparse
+  webpage.sparse
+  $ cd ..
+
+Verify local clone with exclude works
+
+  $ hg clone --exclude data.py myrepo clone3
+  updating to branch default
+  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ cd clone3
+  $ ls
+  backend.sparse
+  index.html
+  readme.txt
+  webpage.sparse
+  $ cd ..
+
+Verify sparse clone profile over ssh works
+
+  $ hg clone -q --enable-profile webpage.sparse ssh://user@dummy/myrepo clone4
+  warning: sparse profile 'webpage.sparse' not found in rev 000000000000 - ignoring it
+  $ cd clone4
+  $ ls
+  index.html
+  $ cd ..

tests/test-sparse-fsmonitor.t

@@ -0,0 +1,44 b''
+This test doesn't yet work due to the way fsmonitor is integrated with test runner
+
+  $ exit 80
+
+test sparse interaction with other extensions
+
+  $ hg init myrepo
+  $ cd myrepo
+  $ cat > .hg/hgrc <<EOF
+  > [extensions]
+  > sparse=
+  > strip=
+  > EOF
+
+Test fsmonitor integration (if available)
+TODO: make fully isolated integration test a'la https://github.com/facebook/watchman/blob/master/tests/integration/WatchmanInstance.py
+(this one is using the systemwide watchman instance)
+
+  $ touch .watchmanconfig
+  $ echo "ignoredir1/" >> .hgignore
+  $ hg commit -Am ignoredir1
+  adding .hgignore
+  $ echo "ignoredir2/" >> .hgignore
+  $ hg commit -m ignoredir2
+
+  $ hg sparse --reset
+  $ hg sparse -I ignoredir1 -I ignoredir2 -I dir1
+
+  $ mkdir ignoredir1 ignoredir2 dir1
+  $ touch ignoredir1/file ignoredir2/file dir1/file
+
+Run status twice to compensate for a condition in fsmonitor where it will check
+ignored files the second time it runs, regardless of previous state (ask @sid0)
+  $ hg status --config extensions.fsmonitor=
+  ? dir1/file
+  $ hg status --config extensions.fsmonitor=
+  ? dir1/file
+
+Test that fsmonitor ignore hash check updates when .hgignore changes
+
+  $ hg up -q ".^"
+  $ hg status --config extensions.fsmonitor=
+  ? dir1/file
+  ? ignoredir2/file

tests/test-sparse-import.t

@@ -0,0 +1,186 b''
+test sparse
+
+  $ hg init myrepo
+  $ cd myrepo
+  $ cat >> $HGRCPATH <<EOF
+  > [extensions]
+  > sparse=
+  > purge=
+  > strip=
+  > rebase=
+  > EOF
+
+  $ echo a > index.html
+  $ echo x > data.py
+  $ echo z > readme.txt
+  $ cat > base.sparse <<EOF
+  > [include]
+  > *.sparse
+  > EOF
+  $ hg ci -Aqm 'initial'
+  $ cat > webpage.sparse <<EOF
+  > %include base.sparse
+  > [include]
+  > *.html
+  > EOF
+  $ hg ci -Aqm 'initial'
+
+Import a rules file against a 'blank' sparse profile
+
+  $ cat > $TESTTMP/rules_to_import <<EOF
+  > [include]
+  > *.py
+  > EOF
+  $ hg sparse --import-rules $TESTTMP/rules_to_import
+  $ ls
+  data.py
+
+  $ hg sparse --reset
+  $ rm .hg/sparse
+
+  $ cat > $TESTTMP/rules_to_import <<EOF
+  > %include base.sparse
+  > [include]
+  > *.py
+  > EOF
+  $ hg sparse --import-rules $TESTTMP/rules_to_import
+  $ ls
+  base.sparse
+  data.py
+  webpage.sparse
+
+  $ hg sparse --reset
+  $ rm .hg/sparse
+
+Start against an existing profile; rules *already active* should be ignored
+
+  $ hg sparse --enable-profile webpage.sparse
+  $ hg sparse --include *.py
+  $ cat > $TESTTMP/rules_to_import <<EOF
+  > %include base.sparse
+  > [include]
+  > *.html
+  > *.txt
+  > [exclude]
+  > *.py
+  > EOF
+  $ hg sparse --import-rules $TESTTMP/rules_to_import
+  $ ls
+  base.sparse
+  index.html
+  readme.txt
+  webpage.sparse
+  $ cat .hg/sparse
+  %include webpage.sparse
+  [include]
+  *.py
+  *.txt
+  [exclude]
+  *.py
+
+  $ hg sparse --reset
+  $ rm .hg/sparse
+
+Same tests, with -Tjson enabled to output summaries
+
+  $ cat > $TESTTMP/rules_to_import <<EOF
+  > [include]
+  > *.py
+  > EOF
+  $ hg sparse --import-rules $TESTTMP/rules_to_import -Tjson
+  [
+   {
+    "exclude_rules_added": 0,
+    "files_added": 0,
+    "files_conflicting": 0,
+    "files_dropped": 4,
+    "include_rules_added": 1,
+    "profiles_added": 0
+   }
+  ]
+
+  $ hg sparse --reset
+  $ rm .hg/sparse
+
+  $ cat > $TESTTMP/rules_to_import <<EOF
+  > %include base.sparse
+  > [include]
+  > *.py
+  > EOF
+  $ hg sparse --import-rules $TESTTMP/rules_to_import -Tjson
+  [
+   {
+    "exclude_rules_added": 0,
+    "files_added": 0,
+    "files_conflicting": 0,
+    "files_dropped": 2,
+    "include_rules_added": 1,
+    "profiles_added": 1
+   }
+  ]
+
+  $ hg sparse --reset
+  $ rm .hg/sparse
+
+  $ hg sparse --enable-profile webpage.sparse
+  $ hg sparse --include *.py
+  $ cat > $TESTTMP/rules_to_import <<EOF
+  > %include base.sparse
+  > [include]
+  > *.html
+  > *.txt
+  > [exclude]
+  > *.py
+  > EOF
+  $ hg sparse --import-rules $TESTTMP/rules_to_import -Tjson
+  [
+   {
+    "exclude_rules_added": 1,
+    "files_added": 1,
+    "files_conflicting": 0,
+    "files_dropped": 1,
+    "include_rules_added": 1,
+    "profiles_added": 0
+   }
+  ]
+
+If importing results in no new rules being added, no refresh should take place!
+
+  $ cat > $TESTTMP/trap_sparse_refresh.py <<EOF
+  > from mercurial import error, extensions
+  > def extsetup(ui):
+  >     def abort_refresh(ui, *args):
+  >         raise error.Abort('sparse._refresh called!')
+  >     def sparseloaded(loaded):
+  >         if not loaded:
+  >             return
+  >         sparse = extensions.find('sparse')
+  >         sparse._refresh = abort_refresh
+  >     extensions.afterloaded('sparse', sparseloaded)
+  > EOF
+  $ cat >> $HGRCPATH <<EOF
+  > [extensions]
+  > trap_sparse_refresh=$TESTTMP/trap_sparse_refresh.py
+  > EOF
+  $ cat > $TESTTMP/rules_to_import <<EOF
+  > [include]
+  > *.py
+  > EOF
+  $ hg sparse --import-rules $TESTTMP/rules_to_import
+
+If an exception is raised during refresh, restore the existing rules again.
+
+  $ cat > $TESTTMP/rules_to_import <<EOF
+  > [exclude]
+  > *.html
+  > EOF
+  $ hg sparse --import-rules $TESTTMP/rules_to_import
+  abort: sparse._refresh called!
+  [255]
+  $ cat .hg/sparse
+  %include webpage.sparse
+  [include]
+  *.py
+  *.txt
+  [exclude]
+  *.py

tests/test-sparse-merges.t

@@ -0,0 +1,62 b''
+test merging things outside of the sparse checkout
+
+  $ hg init myrepo
+  $ cd myrepo
+  $ cat > .hg/hgrc <<EOF
+  > [extensions]
+  > sparse=
+  > EOF
+
+  $ echo foo > foo
+  $ echo bar > bar
+  $ hg add foo bar
+  $ hg commit -m initial
+
+  $ hg branch feature
+  marked working directory as branch feature
+  (branches are permanent and global, did you want a bookmark?)
+  $ echo bar2 >> bar
+  $ hg commit -m 'feature - bar2'
+
+  $ hg update -q default
+  $ hg sparse --exclude 'bar**'
+
+  $ hg merge feature
+  temporarily included 1 file(s) in the sparse checkout for merging
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+
+Verify bar was merged temporarily
+
+  $ ls
+  bar
+  foo
+  $ hg status
+  M bar
+
+Verify bar disappears automatically when the working copy becomes clean
+
+  $ hg commit -m "merged"
+  cleaned up 1 temporarily added file(s) from the sparse checkout
+  $ hg status
+  $ ls
+  foo
+
+  $ hg cat -r . bar
+  bar
+  bar2
+
+Test merging things outside of the sparse checkout that are not in the working
+copy
+
+  $ hg strip -q -r . --config extensions.strip=
+  $ hg up -q feature
+  $ touch branchonly
+  $ hg ci -Aqm 'add branchonly'
+
+  $ hg up -q default
+  $ hg sparse -X branchonly
+  $ hg merge feature
+  temporarily included 2 file(s) in the sparse checkout for merging
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)

tests/test-sparse-profiles.t

@@ -0,0 +1,272 b''
+test sparse
+
+  $ hg init myrepo
+  $ cd myrepo
+  $ cat > .hg/hgrc <<EOF
+  > [extensions]
+  > sparse=
+  > purge=
+  > strip=
+  > rebase=
+  > EOF
+
+  $ echo a > index.html
+  $ echo x > data.py
+  $ echo z > readme.txt
+  $ cat > webpage.sparse <<EOF
+  > # frontend sparse profile
+  > [include]
+  > *.html
+  > EOF
+  $ cat > backend.sparse <<EOF
+  > # backend sparse profile
+  > [include]
+  > *.py
+  > EOF
+  $ hg ci -Aqm 'initial'
+
+  $ hg sparse --include '*.sparse'
+
+Verify enabling a single profile works
+
+  $ hg sparse --enable-profile webpage.sparse
+  $ ls
+  backend.sparse
+  index.html
+  webpage.sparse
+
+Verify enabling two profiles works
+
+  $ hg sparse --enable-profile backend.sparse
+  $ ls
+  backend.sparse
+  data.py
+  index.html
+  webpage.sparse
+
+Verify disabling a profile works
+
+  $ hg sparse --disable-profile webpage.sparse
+  $ ls
+  backend.sparse
+  data.py
+  webpage.sparse
+
+Verify that a profile is updated across multiple commits
+
+  $ cat > webpage.sparse <<EOF
+  > # frontend sparse profile
+  > [include]
+  > *.html
+  > EOF
+  $ cat > backend.sparse <<EOF
+  > # backend sparse profile
+  > [include]
+  > *.py
+  > *.txt
+  > EOF
+
+  $ echo foo >> data.py
+
+  $ hg ci -m 'edit profile'
+  $ ls
+  backend.sparse
+  data.py
+  readme.txt
+  webpage.sparse
+
+  $ hg up -q 0
+  $ ls
+  backend.sparse
+  data.py
+  webpage.sparse
+
+  $ hg up -q 1
+  $ ls
+  backend.sparse
+  data.py
+  readme.txt
+  webpage.sparse
+
+Introduce a conflicting .hgsparse change
+
+  $ hg up -q 0
+  $ cat > backend.sparse <<EOF
+  > # Different backend sparse profile
+  > [include]
+  > *.html
+  > EOF
+  $ echo bar >> data.py
+
+  $ hg ci -qAm "edit profile other"
+  $ ls
+  backend.sparse
+  index.html
+  webpage.sparse
+
+Verify conflicting merge pulls in the conflicting changes
+
+  $ hg merge 1
+  temporarily included 1 file(s) in the sparse checkout for merging
+  merging backend.sparse
+  merging data.py
+  warning: conflicts while merging backend.sparse! (edit, then use 'hg resolve --mark')
+  warning: conflicts while merging data.py! (edit, then use 'hg resolve --mark')
+  0 files updated, 0 files merged, 0 files removed, 2 files unresolved
+  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
+  [1]
+
+  $ rm *.orig
+  $ ls
+  backend.sparse
+  data.py
+  index.html
+  webpage.sparse
+
+Verify resolving the merge removes the temporarily unioned files
+
+  $ cat > backend.sparse <<EOF
+  > # backend sparse profile
+  > [include]
+  > *.html
+  > *.txt
+  > EOF
+  $ hg resolve -m backend.sparse
+
+  $ cat > data.py <<EOF
+  > x
+  > foo
+  > bar
+  > EOF
+  $ hg resolve -m data.py
+  (no more unresolved files)
+
+  $ hg ci -qAm "merge profiles"
+  $ ls
+  backend.sparse
+  index.html
+  readme.txt
+  webpage.sparse
+
+  $ hg cat -r . data.py
+  x
+  foo
+  bar
+
+Verify stripping refreshes dirstate
+
+  $ hg strip -q -r .
+  $ ls
+  backend.sparse
+  index.html
+  webpage.sparse
+
+Verify rebase conflicts pulls in the conflicting changes
+
+  $ hg up -q 1
+  $ ls
+  backend.sparse
+  data.py
+  readme.txt
+  webpage.sparse
+
+  $ hg rebase -d 2
+  rebasing 1:a2b1de640a62 "edit profile"
+  temporarily included 1 file(s) in the sparse checkout for merging
+  merging backend.sparse
+  merging data.py
+  warning: conflicts while merging backend.sparse! (edit, then use 'hg resolve --mark')
+  warning: conflicts while merging data.py! (edit, then use 'hg resolve --mark')
+  unresolved conflicts (see hg resolve, then hg rebase --continue)
+  [1]
+  $ rm *.orig
+  $ ls
+  backend.sparse
+  data.py
+  index.html
+  webpage.sparse
+
+Verify resolving conflict removes the temporary files
+
+  $ cat > backend.sparse <<EOF
+  > [include]
+  > *.html
+  > *.txt
+  > EOF
+  $ hg resolve -m backend.sparse
+
+  $ cat > data.py <<EOF
+  > x
+  > foo
+  > bar
+  > EOF
+  $ hg resolve -m data.py
+  (no more unresolved files)
+  continue: hg rebase --continue
+
+  $ hg rebase -q --continue
+  $ ls
+  backend.sparse
+  index.html
+  readme.txt
+  webpage.sparse
+
+  $ hg cat -r . data.py
+  x
+  foo
+  bar
+
+Test checking out a commit that does not contain the sparse profile. The
+warning message can be suppressed by setting missingwarning = false in
+[sparse] section of your config:
+
+  $ hg sparse --reset
+  $ hg rm *.sparse
+  $ hg commit -m "delete profiles"
+  $ hg up -q ".^"
+  $ hg sparse --enable-profile backend.sparse
+  $ ls
+  index.html
+  readme.txt
+  $ hg up tip | grep warning
+  warning: sparse profile 'backend.sparse' not found in rev bfcb76de99cc - ignoring it
+  [1]
+  $ ls
+  data.py
+  index.html
+  readme.txt
+  $ hg sparse --disable-profile backend.sparse | grep warning
+  warning: sparse profile 'backend.sparse' not found in rev bfcb76de99cc - ignoring it
+  [1]
+  $ cat >> .hg/hgrc <<EOF
+  > [sparse]
+  > missingwarning = false
+  > EOF
+  $ hg sparse --enable-profile backend.sparse
+
+  $ cd ..
+
+Test file permissions changing across a sparse profile change
+  $ hg init sparseperm
+  $ cd sparseperm
+  $ cat > .hg/hgrc <<EOF
+  > [extensions]
+  > sparse=
+  > EOF
+  $ touch a b
+  $ cat > .hgsparse <<EOF
+  > a
+  > EOF
+  $ hg commit -Aqm 'initial'
+  $ chmod a+x b
+  $ hg commit -qm 'make executable'
+  $ cat >> .hgsparse <<EOF
+  > b
+  > EOF
+  $ hg commit -qm 'update profile'
+  $ hg up -q 0
+  $ hg sparse --enable-profile .hgsparse
+  $ hg up -q 2
+  $ ls -l b
+  -rwxr-xr-x* b (glob)
+

tests/test-sparse-verbose-json.t

@@ -0,0 +1,82 b''
+test sparse with --verbose and -T json
+
+  $ hg init myrepo
+  $ cd myrepo
+  $ cat > .hg/hgrc <<EOF
+  > [extensions]
+  > sparse=
+  > strip=
+  > EOF
+
+  $ echo a > show
+  $ echo x > hide
+  $ hg ci -Aqm 'initial'
+
+  $ echo b > show
+  $ echo y > hide
+  $ echo aa > show2
+  $ echo xx > hide2
+  $ hg ci -Aqm 'two'
+
+Verify basic --include and --reset
+
+  $ hg up -q 0
+  $ hg sparse --include 'hide' -Tjson
+  [
+   {
+    "exclude_rules_added": 0,
+    "files_added": 0,
+    "files_conflicting": 0,
+    "files_dropped": 1,
+    "include_rules_added": 1,
+    "profiles_added": 0
+   }
+  ]
+  $ hg sparse --clear-rules
+  $ hg sparse --include 'hide' --verbose
+  removing show
+  Profile # change: 0
+  Include rule # change: 1
+  Exclude rule # change: 0
+
+  $ hg sparse --reset -Tjson
+  [
+   {
+    "exclude_rules_added": 0,
+    "files_added": 1,
+    "files_conflicting": 0,
+    "files_dropped": 0,
+    "include_rules_added": -1,
+    "profiles_added": 0
+   }
+  ]
+  $ hg sparse --include 'hide'
+  $ hg sparse --reset --verbose
+  getting show
+  Profile # change: 0
+  Include rule # change: -1
+  Exclude rule # change: 0
+
+Verifying that problematic files still allow us to see the deltas when forcing:
+
+  $ hg sparse --include 'show*'
+  $ touch hide
+  $ hg sparse --delete 'show*' --force -Tjson
+  pending changes to 'hide'
+  [
+   {
+    "exclude_rules_added": 0,
+    "files_added": 0,
+    "files_conflicting": 1,
+    "files_dropped": 0,
+    "include_rules_added": -1,
+    "profiles_added": 0
+   }
+  ]
+  $ hg sparse --include 'show*' --force
+  pending changes to 'hide'
+  $ hg sparse --delete 'show*' --force --verbose
+  pending changes to 'hide'
+  Profile # change: 0
+  Include rule # change: -1
+  Exclude rule # change: 0

tests/test-sparse.t

@@ -0,0 +1,369 b''
+test sparse
+
+  $ hg init myrepo
+  $ cd myrepo
+  $ cat > .hg/hgrc <<EOF
+  > [extensions]
+  > sparse=
+  > strip=
+  > EOF
+
+  $ echo a > show
+  $ echo x > hide
+  $ hg ci -Aqm 'initial'
+
+  $ echo b > show
+  $ echo y > hide
+  $ echo aa > show2
+  $ echo xx > hide2
+  $ hg ci -Aqm 'two'
+
+Verify basic --include
+
+  $ hg up -q 0
+  $ hg sparse --include 'hide'
+  $ ls
+  hide
+
+Absolute paths outside the repo should just be rejected
+
+  $ hg sparse --include /foo/bar
+  warning: paths cannot start with /, ignoring: ['/foo/bar']
+  $ hg sparse --include '$TESTTMP/myrepo/hide'
+
+  $ hg sparse --include '/root'
+  warning: paths cannot start with /, ignoring: ['/root']
+
+Verify commiting while sparse includes other files
+
+  $ echo z > hide
+  $ hg ci -Aqm 'edit hide'
+  $ ls
+  hide
+  $ hg manifest
+  hide
+  show
+
+Verify --reset brings files back
+
+  $ hg sparse --reset
+  $ ls
+  hide
+  show
+  $ cat hide
+  z
+  $ cat show
+  a
+
+Verify 'hg sparse' default output
+
+  $ hg up -q null
+  $ hg sparse --include 'show*'
+
+  $ hg sparse
+  [include]
+  show*
+  [exclude]
+  
+  
+Verify update only writes included files
+
+  $ hg up -q 0
+  $ ls
+  show
+
+  $ hg up -q 1
+  $ ls
+  show
+  show2
+
+Verify status only shows included files
+
+  $ touch hide
+  $ touch hide3
+  $ echo c > show
+  $ hg status
+  M show
+
+Adding an excluded file should fail
+
+  $ hg add hide3
+  abort: cannot add 'hide3' - it is outside the sparse checkout
+  (include file with `hg sparse --include <pattern>` or use `hg add -s <file>` to include file directory while adding)
+  [255]
+
+Verify deleting sparseness while a file has changes fails
+
+  $ hg sparse --delete 'show*'
+  pending changes to 'hide'
+  abort: cannot change sparseness due to pending changes (delete the files or use --force to bring them back dirty)
+  [255]
+
+Verify deleting sparseness with --force brings back files
+
+  $ hg sparse --delete -f 'show*'
+  pending changes to 'hide'
+  $ ls
+  hide
+  hide2
+  hide3
+  show
+  show2
+  $ hg st
+  M hide
+  M show
+  ? hide3
+
+Verify editing sparseness fails if pending changes
+
+  $ hg sparse --include 'show*'
+  pending changes to 'hide'
+  abort: could not update sparseness due to pending changes
+  [255]
+
+Verify adding sparseness hides files
+
+  $ hg sparse --exclude -f 'hide*'
+  pending changes to 'hide'
+  $ ls
+  hide
+  hide3
+  show
+  show2
+  $ hg st
+  M show
+
+  $ hg up -qC .
+  $ hg purge --all --config extensions.purge=
+  $ ls
+  show
+  show2
+
+Verify rebase temporarily includes excluded files
+
+  $ hg rebase -d 1 -r 2 --config extensions.rebase=
+  rebasing 2:b91df4f39e75 "edit hide" (tip)
+  temporarily included 1 file(s) in the sparse checkout for merging
+  merging hide
+  warning: conflicts while merging hide! (edit, then use 'hg resolve --mark')
+  unresolved conflicts (see hg resolve, then hg rebase --continue)
+  [1]
+
+  $ hg sparse
+  [include]
+  
+  [exclude]
+  hide*
+  
+  Temporarily Included Files (for merge/rebase):
+  hide
+
+  $ cat hide
+  <<<<<<< dest:   39278f7c08a9 - test: two
+  y
+  =======
+  z
+  >>>>>>> source: b91df4f39e75 - test: edit hide
+
+Verify aborting a rebase cleans up temporary files
+
+  $ hg rebase --abort --config extensions.rebase=
+  cleaned up 1 temporarily added file(s) from the sparse checkout
+  rebase aborted
+  $ rm hide.orig
+
+  $ ls
+  show
+  show2
+
+Verify merge fails if merging excluded files
+
+  $ hg up -q 1
+  $ hg merge -r 2
+  temporarily included 1 file(s) in the sparse checkout for merging
+  merging hide
+  warning: conflicts while merging hide! (edit, then use 'hg resolve --mark')
+  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
+  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
+  [1]
+  $ hg sparse
+  [include]
+  
+  [exclude]
+  hide*
+  
+  Temporarily Included Files (for merge/rebase):
+  hide
+
+  $ hg up -C .
+  cleaned up 1 temporarily added file(s) from the sparse checkout
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg sparse
+  [include]
+  
+  [exclude]
+  hide*
+  
+
+Verify strip -k resets dirstate correctly
+
+  $ hg status
+  $ hg sparse
+  [include]
+  
+  [exclude]
+  hide*
+  
+  $ hg log -r . -T '{rev}\n' --stat
+  1
+   hide  |  2 +-
+   hide2 |  1 +
+   show  |  2 +-
+   show2 |  1 +
+   4 files changed, 4 insertions(+), 2 deletions(-)
+  
+  $ hg strip -r . -k
+  saved backup bundle to $TESTTMP/myrepo/.hg/strip-backup/39278f7c08a9-ce59e002-backup.hg (glob)
+  $ hg status
+  M show
+  ? show2
+
+Verify rebase succeeds if all changed files are in sparse checkout
+
+  $ hg commit -Aqm "add show2"
+  $ hg rebase -d 1 --config extensions.rebase=
+  rebasing 2:bdde55290160 "add show2" (tip)
+  saved backup bundle to $TESTTMP/myrepo/.hg/strip-backup/bdde55290160-216ed9c6-backup.hg (glob)
+
+Verify log --sparse only shows commits that affect the sparse checkout
+
+  $ hg log -T '{rev} '
+  2 1 0  (no-eol)
+  $ hg log --sparse -T '{rev} '
+  2 0  (no-eol)
+
+Test status on a file in a subdir
+
+  $ mkdir -p dir1/dir2
+  $ touch dir1/dir2/file
+  $ hg sparse -I dir1/dir2
+  $ hg status
+  ? dir1/dir2/file
+
+Test that add -s adds dirs to sparse profile
+
+  $ hg sparse --reset
+  $ hg sparse --include empty
+  $ hg sparse
+  [include]
+  empty
+  [exclude]
+  
+  
+
+  $ mkdir add
+  $ touch add/foo
+  $ touch add/bar
+  $ hg add add/foo
+  abort: cannot add 'add/foo' - it is outside the sparse checkout
+  (include file with `hg sparse --include <pattern>` or use `hg add -s <file>` to include file directory while adding)
+  [255]
+  $ hg add -s add/foo
+  $ hg st
+  A add/foo
+  ? add/bar
+  $ hg sparse
+  [include]
+  add
+  empty
+  [exclude]
+  
+  
+  $ hg add -s add/*
+  add/foo already tracked!
+  $ hg st
+  A add/bar
+  A add/foo
+  $ hg sparse
+  [include]
+  add
+  empty
+  [exclude]
+  
+  
+
+  $ cd ..
+
+Test non-sparse repos work while sparse is loaded
+  $ hg init sparserepo
+  $ hg init nonsparserepo
+  $ cd sparserepo
+  $ cat > .hg/hgrc <<EOF
+  > [extensions]
+  > sparse=
+  > EOF
+  $ cd ../nonsparserepo
+  $ echo x > x && hg add x && hg commit -qAm x
+  $ cd ../sparserepo
+  $ hg clone ../nonsparserepo ../nonsparserepo2
+  updating to branch default
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+Test debugrebuilddirstate
+  $ cd ../sparserepo
+  $ touch included
+  $ touch excluded
+  $ hg add included excluded
+  $ hg commit -m 'a commit' -q
+  $ cp .hg/dirstate ../dirstateboth
+  $ hg sparse -X excluded
+  $ cp ../dirstateboth .hg/dirstate
+  $ hg debugrebuilddirstate
+  $ hg debugdirstate
+  n   0         -1 unset               included
+
+Test debugdirstate --minimal where file is in the parent manifest but not the
+dirstate
+  $ hg sparse -X included
+  $ hg debugdirstate
+  $ cp .hg/dirstate ../dirstateallexcluded
+  $ hg sparse --reset
+  $ hg sparse -X excluded
+  $ cp ../dirstateallexcluded .hg/dirstate
+  $ touch includedadded
+  $ hg add includedadded
+  $ hg debugdirstate --nodates
+  a   0         -1 unset               includedadded
+  $ hg debugrebuilddirstate --minimal
+  $ hg debugdirstate --nodates
+  n   0         -1 unset               included
+  a   0         -1 * includedadded (glob)
+
+Test debugdirstate --minimal where a file is not in parent manifest
+but in the dirstate. This should take into account excluded files in the
+manifest
+  $ cp ../dirstateboth .hg/dirstate
+  $ touch includedadded
+  $ hg add includedadded
+  $ touch excludednomanifest
+  $ hg add excludednomanifest
+  $ cp .hg/dirstate ../moreexcluded
+  $ hg forget excludednomanifest
+  $ rm excludednomanifest
+  $ hg sparse -X excludednomanifest
+  $ cp ../moreexcluded .hg/dirstate
+  $ hg manifest
+  excluded
+  included
+We have files in the dirstate that are included and excluded. Some are in the
+manifest and some are not.
+  $ hg debugdirstate --nodates
+  n 644          0 * excluded (glob)
+  a   0         -1 * excludednomanifest (glob)
+  n 644          0 * included (glob)
+  a   0         -1 * includedadded (glob)
+  $ hg debugrebuilddirstate --minimal
+  $ hg debugdirstate --nodates
+  n 644          0 * included (glob)
+  a   0         -1 * includedadded (glob)
+