mercurial/pathutil.py

revset: improve head revset performance

Previously the head() revset would iterate over every item in the subset and
check if it was a head.  Since the subset is often the entire repo, this was
slow on large repos. Now we iterate over each item in the head list and check if
it's in the subset, which results in much less work.

hg log -r 'head()' on a large repo:
Before: 0.95s
After: 0.28s

import os, errno, stat

import util
from i18n import _

class pathauditor(object):
    '''ensure that a filesystem path contains no banned components.
    the following properties of a path are checked:

    - ends with a directory separator
    - under top-level .hg
    - starts at the root of a windows drive
    - contains ".."
    - traverses a symlink (e.g. a/symlink_here/b)
    - inside a nested repository (a callback can be used to approve
      some nested repositories, e.g., subrepositories)
    '''

    def __init__(self, root, callback=None):
        self.audited = set()
        self.auditeddir = set()
        self.root = root
        self.callback = callback
        if os.path.lexists(root) and not util.checkcase(root):
            self.normcase = util.normcase
        else:
            self.normcase = lambda x: x

    def __call__(self, path):
        '''Check the relative path.
        path may contain a pattern (e.g. foodir/**.txt)'''

        path = util.localpath(path)
        normpath = self.normcase(path)
        if normpath in self.audited:
            return
        # AIX ignores "/" at end of path, others raise EISDIR.
        if util.endswithsep(path):
            raise util.Abort(_("path ends in directory separator: %s") % path)
        parts = util.splitpath(path)
        if (os.path.splitdrive(path)[0]
            or parts[0].lower() in ('.hg', '.hg.', '')
            or os.pardir in parts):
            raise util.Abort(_("path contains illegal component: %s") % path)
        if '.hg' in path.lower():
            lparts = [p.lower() for p in parts]
            for p in '.hg', '.hg.':
                if p in lparts[1:]:
                    pos = lparts.index(p)
                    base = os.path.join(*parts[:pos])
                    raise util.Abort(_("path '%s' is inside nested repo %r")
                                     % (path, base))

        normparts = util.splitpath(normpath)
        assert len(parts) == len(normparts)

        parts.pop()
        normparts.pop()
        prefixes = []
        while parts:
            prefix = os.sep.join(parts)
            normprefix = os.sep.join(normparts)
            if normprefix in self.auditeddir:
                break
            curpath = os.path.join(self.root, prefix)
            try:
                st = os.lstat(curpath)
            except OSError, err:
                # EINVAL can be raised as invalid path syntax under win32.
                # They must be ignored for patterns can be checked too.
                if err.errno not in (errno.ENOENT, errno.ENOTDIR, errno.EINVAL):
                    raise
            else:
                if stat.S_ISLNK(st.st_mode):
                    raise util.Abort(
                        _('path %r traverses symbolic link %r')
                        % (path, prefix))
                elif (stat.S_ISDIR(st.st_mode) and
                      os.path.isdir(os.path.join(curpath, '.hg'))):
                    if not self.callback or not self.callback(curpath):
                        raise util.Abort(_("path '%s' is inside nested "
                                           "repo %r")
                                         % (path, prefix))
            prefixes.append(normprefix)
            parts.pop()
            normparts.pop()

        self.audited.add(normpath)
        # only add prefixes to the cache after checking everything: we don't
        # want to add "foo/bar/baz" before checking if there's a "foo/.hg"
        self.auditeddir.update(prefixes)

    def check(self, path):
        try:
            self(path)
            return True
        except (OSError, util.Abort):
            return False

def canonpath(root, cwd, myname, auditor=None):
    '''return the canonical path of myname, given cwd and root'''
    if util.endswithsep(root):
        rootsep = root
    else:
        rootsep = root + os.sep
    name = myname
    if not os.path.isabs(name):
        name = os.path.join(root, cwd, name)
    name = os.path.normpath(name)
    if auditor is None:
        auditor = pathauditor(root)
    if name != rootsep and name.startswith(rootsep):
        name = name[len(rootsep):]
        auditor(name)
        return util.pconvert(name)
    elif name == root:
        return ''
    else:
        # Determine whether `name' is in the hierarchy at or beneath `root',
        # by iterating name=dirname(name) until that causes no change (can't
        # check name == '/', because that doesn't work on windows). The list
        # `rel' holds the reversed list of components making up the relative
        # file name we want.
        rel = []
        while True:
            try:
                s = util.samefile(name, root)
            except OSError:
                s = False
            if s:
                if not rel:
                    # name was actually the same as root (maybe a symlink)
                    return ''
                rel.reverse()
                name = os.path.join(*rel)
                auditor(name)
                return util.pconvert(name)
            dirname, basename = util.split(name)
            rel.append(basename)
            if dirname == name:
                break
            name = dirname

        raise util.Abort(_("%s not under root '%s'") % (myname, root))