mercurial/httprepo.py

rebase: allow collapsing branches in place (issue3111)

We allow rebase plus collapse, but not collapse only? I imagine people would
rebase first then collapse once they are sure the rebase is correct and it is
the right time to finish it.

I was reluctant to submit this patch for reasons detailed below, but it
improves rebase --collapse usefulness so much it is worth the ugliness.

The fix is ugly because we should be fixing the collapse code path rather than
the merge. Collapsing by merging changesets repeatedly is inefficient compared
to what commit --amend does: commitctx(), update, strip. The problem with the
latter is, to generate the synthetic changeset, copy records are gathered with
copies.pathcopies(). copies.pathcopies() is still implemented with merging in
mind and discards information like file replaced by the copy of another,
criss-cross copies and so forth. I believe this information should not be lost,
even if we decide not to interpret it fully later, at merge time.

The second issue with improving rebase --collapse is the option should not be
there to begin with. Rebasing and collapsing are orthogonal and a dedicated
command would probably enable a better, simpler ui. We should avoid advertizing
rebase --collapse, but with this fix it becomes the best shipped solution to
collapse changesets.

And for the record, available techniques are:
- revert + commit + strip: lose copies
- mq/qfold: repeated patching() (mostly correct, fragile)
- rebase: repeated merges (mostly correct, fragile)
- collapse: revert + tag rewriting wizardry, lose copies
- histedit: repeated patching() (mostly correct, fragile)
- amend: copies.pathcopies() + commitctx() + update + strip

# httprepo.py - HTTP repository proxy classes for mercurial
#
# Copyright 2005, 2006 Matt Mackall <[e-mail]>
# Copyright 2006 Vadim Gelfer <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from node import nullid
from i18n import _
import changegroup, statichttprepo, error, httpconnection, url, util, wireproto
import os, urllib, urllib2, zlib, httplib
import errno, socket

def zgenerator(f):
    zd = zlib.decompressobj()
    try:
        for chunk in util.filechunkiter(f):
            while chunk:
                yield zd.decompress(chunk, 2**18)
                chunk = zd.unconsumed_tail
    except httplib.HTTPException:
        raise IOError(None, _('connection ended unexpectedly'))
    yield zd.flush()

class httprepository(wireproto.wirerepository):
    def __init__(self, ui, path):
        self.path = path
        self.caps = None
        self.handler = None
        self.urlopener = None
        u = util.url(path)
        if u.query or u.fragment:
            raise util.Abort(_('unsupported URL component: "%s"') %
                             (u.query or u.fragment))

        # urllib cannot handle URLs with embedded user or passwd
        self._url, authinfo = u.authinfo()

        self.ui = ui
        self.ui.debug('using %s\n' % self._url)

        self.urlopener = url.opener(ui, authinfo)

    def __del__(self):
        if self.urlopener:
            for h in self.urlopener.handlers:
                h.close()
                getattr(h, "close_all", lambda : None)()

    def url(self):
        return self.path

    # look up capabilities only when needed

    def _fetchcaps(self):
        self.caps = set(self._call('capabilities').split())

    def get_caps(self):
        if self.caps is None:
            try:
                self._fetchcaps()
            except error.RepoError:
                self.caps = set()
            self.ui.debug('capabilities: %s\n' %
                          (' '.join(self.caps or ['none'])))
        return self.caps

    capabilities = property(get_caps)

    def lock(self):
        raise util.Abort(_('operation not supported over http'))

    def _callstream(self, cmd, **args):
        if cmd == 'pushkey':
            args['data'] = ''
        data = args.pop('data', None)
        size = 0
        if util.safehasattr(data, 'length'):
            size = data.length
        elif data is not None:
            size = len(data)
        headers = args.pop('headers', {})

        if size and self.ui.configbool('ui', 'usehttp2', False):
            headers['Expect'] = '100-Continue'
            headers['X-HgHttp2'] = '1'

        self.ui.debug("sending %s command\n" % cmd)
        q = [('cmd', cmd)]
        headersize = 0
        if len(args) > 0:
            httpheader = self.capable('httpheader')
            if httpheader:
                headersize = int(httpheader.split(',')[0])
        if headersize > 0:
            # The headers can typically carry more data than the URL.
            encargs = urllib.urlencode(sorted(args.items()))
            headerfmt = 'X-HgArg-%s'
            contentlen = headersize - len(headerfmt % '000' + ': \r\n')
            headernum = 0
            for i in xrange(0, len(encargs), contentlen):
                headernum += 1
                header = headerfmt % str(headernum)
                headers[header] = encargs[i:i + contentlen]
            varyheaders = [headerfmt % str(h) for h in range(1, headernum + 1)]
            headers['Vary'] = ','.join(varyheaders)
        else:
            q += sorted(args.items())
        qs = '?%s' % urllib.urlencode(q)
        cu = "%s%s" % (self._url, qs)
        req = urllib2.Request(cu, data, headers)
        if data is not None:
            self.ui.debug("sending %s bytes\n" % size)
            req.add_unredirected_header('Content-Length', '%d' % size)
        try:
            resp = self.urlopener.open(req)
        except urllib2.HTTPError, inst:
            if inst.code == 401:
                raise util.Abort(_('authorization failed'))
            raise
        except httplib.HTTPException, inst:
            self.ui.debug('http error while sending %s command\n' % cmd)
            self.ui.traceback()
            raise IOError(None, inst)
        except IndexError:
            # this only happens with Python 2.3, later versions raise URLError
            raise util.Abort(_('http error, possibly caused by proxy setting'))
        # record the url we got redirected to
        resp_url = resp.geturl()
        if resp_url.endswith(qs):
            resp_url = resp_url[:-len(qs)]
        if self._url.rstrip('/') != resp_url.rstrip('/'):
            if not self.ui.quiet:
                self.ui.warn(_('real URL is %s\n') % resp_url)
        self._url = resp_url
        try:
            proto = resp.getheader('content-type')
        except AttributeError:
            proto = resp.headers.get('content-type', '')

        safeurl = util.hidepassword(self._url)
        if proto.startswith('application/hg-error'):
            raise error.OutOfBandError(resp.read())
        # accept old "text/plain" and "application/hg-changegroup" for now
        if not (proto.startswith('application/mercurial-') or
                proto.startswith('text/plain') or
                proto.startswith('application/hg-changegroup')):
            self.ui.debug("requested URL: '%s'\n" % util.hidepassword(cu))
            raise error.RepoError(
                _("'%s' does not appear to be an hg repository:\n"
                  "---%%<--- (%s)\n%s\n---%%<---\n")
                % (safeurl, proto or 'no content-type', resp.read()))

        if proto.startswith('application/mercurial-'):
            try:
                version = proto.split('-', 1)[1]
                version_info = tuple([int(n) for n in version.split('.')])
            except ValueError:
                raise error.RepoError(_("'%s' sent a broken Content-Type "
                                        "header (%s)") % (safeurl, proto))
            if version_info > (0, 1):
                raise error.RepoError(_("'%s' uses newer protocol %s") %
                                      (safeurl, version))

        return resp

    def _call(self, cmd, **args):
        fp = self._callstream(cmd, **args)
        try:
            return fp.read()
        finally:
            # if using keepalive, allow connection to be reused
            fp.close()

    def _callpush(self, cmd, cg, **args):
        # have to stream bundle to a temp file because we do not have
        # http 1.1 chunked transfer.

        types = self.capable('unbundle')
        try:
            types = types.split(',')
        except AttributeError:
            # servers older than d1b16a746db6 will send 'unbundle' as a
            # boolean capability. They only support headerless/uncompressed
            # bundles.
            types = [""]
        for x in types:
            if x in changegroup.bundletypes:
                type = x
                break

        tempname = changegroup.writebundle(cg, None, type)
        fp = httpconnection.httpsendfile(self.ui, tempname, "rb")
        headers = {'Content-Type': 'application/mercurial-0.1'}

        try:
            try:
                r = self._call(cmd, data=fp, headers=headers, **args)
                vals = r.split('\n', 1)
                if len(vals) < 2:
                    raise error.ResponseError(_("unexpected response:"), r)
                return vals
            except socket.error, err:
                if err.args[0] in (errno.ECONNRESET, errno.EPIPE):
                    raise util.Abort(_('push failed: %s') % err.args[1])
                raise util.Abort(err.args[1])
        finally:
            fp.close()
            os.unlink(tempname)

    def _abort(self, exception):
        raise exception

    def _decompress(self, stream):
        return util.chunkbuffer(zgenerator(stream))

class httpsrepository(httprepository):
    def __init__(self, ui, path):
        if not url.has_https:
            raise util.Abort(_('Python support for SSL and HTTPS '
                               'is not installed'))
        httprepository.__init__(self, ui, path)

def instance(ui, path, create):
    if create:
        raise util.Abort(_('cannot create new http repository'))
    try:
        if path.startswith('https:'):
            inst = httpsrepository(ui, path)
        else:
            inst = httprepository(ui, path)
        try:
            # Try to do useful work when checking compatibility.
            # Usually saves a roundtrip since we want the caps anyway.
            inst._fetchcaps()
        except error.RepoError:
            # No luck, try older compatibility check.
            inst.between([(nullid, nullid)])
        return inst
    except error.RepoError, httpexception:
        try:
            r = statichttprepo.instance(ui, "static-" + path, create)
            ui.note('(falling back to static-http)\n')
            return r
        except error.RepoError:
            raise httpexception # use the original http RepoError instead