view mercurial/httppeer.py @ 48687:f8f2ecdde4b5

branchmap: skip obsolete revisions while computing heads

It's time to make this part of core Mercurial obsolescence-aware.

Not considering obsolete revisions when computing heads is clearly what
Mercurial should do. But there are a couple of small issues:

- Let's say tip of the repo is obsolete. There are two ways of finding tiprev
  for branchcache (both are in use): looking at input data for update() and
  looking at computed heads after update(). Previously, repo tip would be
  tiprev of the branchcache. With this patch, an obsolete revision can no
  longer be tiprev. And depending on what way we use for finding tiprev (input
  data vs computed heads) we'll get a different result. This is relevant when
  recomputing cache key from cache contents, and may lead to updating cache for
  obsolete revisions multiple times (not from scratch, because it still would
  be considered valid for a subset of revisions in the repo).

- If all commits on a branch are obsolete, the branchcache will include that
  branch, but the list of heads will be empty (that's why there's now `if not
  heads` when recomputing tiprev/tipnode from cache contents). Having an entry
  for every branch is currently required for notify extension (and
  test-notify.t to pass), because notify doesn't handle revsets in its
  subscription config very well and will throw an error if e.g. a branch
  doesn't exist.

- Cloning static HTTP repos may try to stat() a non-existent obsstore file. The
  issue is that we now care about obsolescence during clone, but statichttpvfs
  doesn't implement a stat method, so a regular vfs.stat() is used, and it
  assumes that file is local and calls os.stat().  During a clone, we're trying
  to stat() .hg/store/obsstore, but in static HTTP case we provide a literal
  URL to the obsstore file on the remote as if it were a local file path. On
  windows it actually results in a failure in test-static-http.t.

The first issue is going to be addressed in a series dedicated to making sure
branchcache is properly and timely written on disk (it wasn't perfect even
before this patch, but there aren't enough tests to demonstrate that). The
second issue will be addressed in a future patch for notify extension that will
make it not raise an exception if a branch doesn't exist. And the third one was
partially addressed in the previous patch in this series and will be properly
fixed in a future patch when this series is accepted.

filteredhash() grows a keyword argument to make sure that branchcache is also
invalidated when there are new obsolete revisions in its repo view. This way
the on-disk cache format is unchanged and compatible between versions (although
it will obviously be recomputed when switching versions before/after this patch
and the repo has obsolete revisions).

There's one test that uses plain `hg up` without arguments while updated to a
pruned commit. To make this test pass, simply return current working directory
parent. Later in this series this code will be replaced by what prune command
does: updating to the closest non-obsolete ancestor.

Test changes:

test-branch-change.t: update branch head and cache update message. The head of
default listed in hg heads is changed because revision 2 was rewritten as 7,
and 1 is the closest ancestor on the same branch, so it's the head of default
now.

The cache invalidation message appears now because of the cache hash change,
since we're now accounting for obsolete revisions. Here's some context:

"served.hidden" repo filter means everything is visible (no filtered
revisions), so before this series branch2-served.hidden file would not contain
any cache hash, only revnum and node. Now it also has a hash when there are
obsolete changesets in the repo. The command that the message appears for is
changing branch of 5 and 6, which are now obsolete, so the cache hash changes.

In general, when cache is simply out-of-date, it can be updated using the old
version as a base. But if cache hash differs, then the cache for that
particular repo filter is recomputed (at least with the current
implementation). This is what happens here.

test-obsmarker-template.t: the pull reports 2 heads changed, but after that the
repo correctly sees only 1. The new message could be better, but it's still an
improvement over the previous one where hg pull suggested merging with an
obsolete revision.

test-obsolete.t: we can see these revisions in hg log --hidden, but they
shouldn't be considered heads even with --hidden.

test-rebase-obsolete{,2}.t: there were new heads created previously after
making new orphan changesets, but they weren't detected. Now we are properly
detecting and reporting them.

test-rebase-obsolete4.t: there's only one head now because the other head is
pruned and was falsely reported before.

test-static-http.t: add obsstore to the list of requested files. This file
doesn't exist on the remotes, but clients want it anyway (they get 404). This
is fine, because there are other nonexistent files that clients request, like
.hg/bookmarks or .hg/cache/tags2-served.

Differential Revision: https://phab.mercurial-scm.org/D12097

# httppeer.py - HTTP repository proxy classes for mercurial
#
# Copyright 2005, 2006 Olivia 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 __future__ import absolute_import

import errno
import io
import os
import socket
import struct

from .i18n import _
from .pycompat import getattr
from . import (
    bundle2,
    error,
    httpconnection,
    pycompat,
    statichttprepo,
    url as urlmod,
    util,
    wireprotov1peer,
)
from .utils import urlutil

httplib = util.httplib
urlerr = util.urlerr
urlreq = util.urlreq


def encodevalueinheaders(value, header, limit):
    """Encode a string value into multiple HTTP headers.

    ``value`` will be encoded into 1 or more HTTP headers with the names
    ``header-<N>`` where ``<N>`` is an integer starting at 1. Each header
    name + value will be at most ``limit`` bytes long.

    Returns an iterable of 2-tuples consisting of header names and
    values as native strings.
    """
    # HTTP Headers are ASCII. Python 3 requires them to be unicodes,
    # not bytes. This function always takes bytes in as arguments.
    fmt = pycompat.strurl(header) + r'-%s'
    # Note: it is *NOT* a bug that the last bit here is a bytestring
    # and not a unicode: we're just getting the encoded length anyway,
    # and using an r-string to make it portable between Python 2 and 3
    # doesn't work because then the \r is a literal backslash-r
    # instead of a carriage return.
    valuelen = limit - len(fmt % '000') - len(b': \r\n')
    result = []

    n = 0
    for i in pycompat.xrange(0, len(value), valuelen):
        n += 1
        result.append((fmt % str(n), pycompat.strurl(value[i : i + valuelen])))

    return result


class _multifile(object):
    def __init__(self, *fileobjs):
        for f in fileobjs:
            if not util.safehasattr(f, b'length'):
                raise ValueError(
                    b'_multifile only supports file objects that '
                    b'have a length but this one does not:',
                    type(f),
                    f,
                )
        self._fileobjs = fileobjs
        self._index = 0

    @property
    def length(self):
        return sum(f.length for f in self._fileobjs)

    def read(self, amt=None):
        if amt <= 0:
            return b''.join(f.read() for f in self._fileobjs)
        parts = []
        while amt and self._index < len(self._fileobjs):
            parts.append(self._fileobjs[self._index].read(amt))
            got = len(parts[-1])
            if got < amt:
                self._index += 1
            amt -= got
        return b''.join(parts)

    def seek(self, offset, whence=os.SEEK_SET):
        if whence != os.SEEK_SET:
            raise NotImplementedError(
                b'_multifile does not support anything other'
                b' than os.SEEK_SET for whence on seek()'
            )
        if offset != 0:
            raise NotImplementedError(
                b'_multifile only supports seeking to start, but that '
                b'could be fixed if you need it'
            )
        for f in self._fileobjs:
            f.seek(0)
        self._index = 0


def makev1commandrequest(
    ui, requestbuilder, caps, capablefn, repobaseurl, cmd, args
):
    """Make an HTTP request to run a command for a version 1 client.

    ``caps`` is a set of known server capabilities. The value may be
    None if capabilities are not yet known.

    ``capablefn`` is a function to evaluate a capability.

    ``cmd``, ``args``, and ``data`` define the command, its arguments, and
    raw data to pass to it.
    """
    if cmd == b'pushkey':
        args[b'data'] = b''
    data = args.pop(b'data', None)
    headers = args.pop(b'headers', {})

    ui.debug(b"sending %s command\n" % cmd)
    q = [(b'cmd', cmd)]
    headersize = 0
    # Important: don't use self.capable() here or else you end up
    # with infinite recursion when trying to look up capabilities
    # for the first time.
    postargsok = caps is not None and b'httppostargs' in caps

    # Send arguments via POST.
    if postargsok and args:
        strargs = urlreq.urlencode(sorted(args.items()))
        if not data:
            data = strargs
        else:
            if isinstance(data, bytes):
                i = io.BytesIO(data)
                i.length = len(data)
                data = i
            argsio = io.BytesIO(strargs)
            argsio.length = len(strargs)
            data = _multifile(argsio, data)
        headers['X-HgArgs-Post'] = len(strargs)
    elif args:
        # Calling self.capable() can infinite loop if we are calling
        # "capabilities". But that command should never accept wire
        # protocol arguments. So this should never happen.
        assert cmd != b'capabilities'
        httpheader = capablefn(b'httpheader')
        if httpheader:
            headersize = int(httpheader.split(b',', 1)[0])

        # Send arguments via HTTP headers.
        if headersize > 0:
            # The headers can typically carry more data than the URL.
            encoded_args = urlreq.urlencode(sorted(args.items()))
            for header, value in encodevalueinheaders(
                encoded_args, b'X-HgArg', headersize
            ):
                headers[header] = value
        # Send arguments via query string (Mercurial <1.9).
        else:
            q += sorted(args.items())

    qs = b'?%s' % urlreq.urlencode(q)
    cu = b"%s%s" % (repobaseurl, qs)
    size = 0
    if util.safehasattr(data, b'length'):
        size = data.length
    elif data is not None:
        size = len(data)
    if data is not None and 'Content-Type' not in headers:
        headers['Content-Type'] = 'application/mercurial-0.1'

    # Tell the server we accept application/mercurial-0.2 and multiple
    # compression formats if the server is capable of emitting those
    # payloads.
    # Note: Keep this set empty by default, as client advertisement of
    # protocol parameters should only occur after the handshake.
    protoparams = set()

    mediatypes = set()
    if caps is not None:
        mt = capablefn(b'httpmediatype')
        if mt:
            protoparams.add(b'0.1')
            mediatypes = set(mt.split(b','))

        protoparams.add(b'partial-pull')

    if b'0.2tx' in mediatypes:
        protoparams.add(b'0.2')

    if b'0.2tx' in mediatypes and capablefn(b'compression'):
        # We /could/ compare supported compression formats and prune
        # non-mutually supported or error if nothing is mutually supported.
        # For now, send the full list to the server and have it error.
        comps = [
            e.wireprotosupport().name
            for e in util.compengines.supportedwireengines(util.CLIENTROLE)
        ]
        protoparams.add(b'comp=%s' % b','.join(comps))

    if protoparams:
        protoheaders = encodevalueinheaders(
            b' '.join(sorted(protoparams)), b'X-HgProto', headersize or 1024
        )
        for header, value in protoheaders:
            headers[header] = value

    varyheaders = []
    for header in headers:
        if header.lower().startswith('x-hg'):
            varyheaders.append(header)

    if varyheaders:
        headers['Vary'] = ','.join(sorted(varyheaders))

    req = requestbuilder(pycompat.strurl(cu), data, headers)

    if data is not None:
        ui.debug(b"sending %d bytes\n" % size)
        req.add_unredirected_header('Content-Length', '%d' % size)

    return req, cu, qs


def _reqdata(req):
    """Get request data, if any. If no data, returns None."""
    if pycompat.ispy3:
        return req.data
    if not req.has_data():
        return None
    return req.get_data()


def sendrequest(ui, opener, req):
    """Send a prepared HTTP request.

    Returns the response object.
    """
    dbg = ui.debug
    if ui.debugflag and ui.configbool(b'devel', b'debug.peer-request'):
        line = b'devel-peer-request: %s\n'
        dbg(
            line
            % b'%s %s'
            % (
                pycompat.bytesurl(req.get_method()),
                pycompat.bytesurl(req.get_full_url()),
            )
        )
        hgargssize = None

        for header, value in sorted(req.header_items()):
            header = pycompat.bytesurl(header)
            value = pycompat.bytesurl(value)
            if header.startswith(b'X-hgarg-'):
                if hgargssize is None:
                    hgargssize = 0
                hgargssize += len(value)
            else:
                dbg(line % b'  %s %s' % (header, value))

        if hgargssize is not None:
            dbg(
                line
                % b'  %d bytes of commands arguments in headers'
                % hgargssize
            )
        data = _reqdata(req)
        if data is not None:
            length = getattr(data, 'length', None)
            if length is None:
                length = len(data)
            dbg(line % b'  %d bytes of data' % length)

        start = util.timer()

    res = None
    try:
        res = opener.open(req)
    except urlerr.httperror as inst:
        if inst.code == 401:
            raise error.Abort(_(b'authorization failed'))
        raise
    except httplib.HTTPException as inst:
        ui.debug(
            b'http error requesting %s\n'
            % urlutil.hidepassword(req.get_full_url())
        )
        ui.traceback()
        raise IOError(None, inst)
    finally:
        if ui.debugflag and ui.configbool(b'devel', b'debug.peer-request'):
            code = res.code if res else -1
            dbg(
                line
                % b'  finished in %.4f seconds (%d)'
                % (util.timer() - start, code)
            )

    # Insert error handlers for common I/O failures.
    urlmod.wrapresponse(res)

    return res


class RedirectedRepoError(error.RepoError):
    def __init__(self, msg, respurl):
        super(RedirectedRepoError, self).__init__(msg)
        self.respurl = respurl


def parsev1commandresponse(ui, baseurl, requrl, qs, resp, compressible):
    # record the url we got redirected to
    redirected = False
    respurl = pycompat.bytesurl(resp.geturl())
    if respurl.endswith(qs):
        respurl = respurl[: -len(qs)]
        qsdropped = False
    else:
        qsdropped = True

    if baseurl.rstrip(b'/') != respurl.rstrip(b'/'):
        redirected = True
        if not ui.quiet:
            ui.warn(_(b'real URL is %s\n') % respurl)

    try:
        proto = pycompat.bytesurl(resp.getheader('content-type', ''))
    except AttributeError:
        proto = pycompat.bytesurl(resp.headers.get('content-type', ''))

    safeurl = urlutil.hidepassword(baseurl)
    if proto.startswith(b'application/hg-error'):
        raise error.OutOfBandError(resp.read())

    # Pre 1.0 versions of Mercurial used text/plain and
    # application/hg-changegroup. We don't support such old servers.
    if not proto.startswith(b'application/mercurial-'):
        ui.debug(b"requested URL: '%s'\n" % urlutil.hidepassword(requrl))
        msg = _(
            b"'%s' does not appear to be an hg repository:\n"
            b"---%%<--- (%s)\n%s\n---%%<---\n"
        ) % (safeurl, proto or b'no content-type', resp.read(1024))

        # Some servers may strip the query string from the redirect. We
        # raise a special error type so callers can react to this specially.
        if redirected and qsdropped:
            raise RedirectedRepoError(msg, respurl)
        else:
            raise error.RepoError(msg)

    try:
        subtype = proto.split(b'-', 1)[1]

        version_info = tuple([int(n) for n in subtype.split(b'.')])
    except ValueError:
        raise error.RepoError(
            _(b"'%s' sent a broken Content-Type header (%s)") % (safeurl, proto)
        )

    # TODO consider switching to a decompression reader that uses
    # generators.
    if version_info == (0, 1):
        if compressible:
            resp = util.compengines[b'zlib'].decompressorreader(resp)

    elif version_info == (0, 2):
        # application/mercurial-0.2 always identifies the compression
        # engine in the payload header.
        elen = struct.unpack(b'B', util.readexactly(resp, 1))[0]
        ename = util.readexactly(resp, elen)
        engine = util.compengines.forwiretype(ename)

        resp = engine.decompressorreader(resp)
    else:
        raise error.RepoError(
            _(b"'%s' uses newer protocol %s") % (safeurl, subtype)
        )

    return respurl, proto, resp


class httppeer(wireprotov1peer.wirepeer):
    def __init__(self, ui, path, url, opener, requestbuilder, caps):
        self.ui = ui
        self._path = path
        self._url = url
        self._caps = caps
        self.limitedarguments = caps is not None and b'httppostargs' not in caps
        self._urlopener = opener
        self._requestbuilder = requestbuilder

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

    # Begin of ipeerconnection interface.

    def url(self):
        return self._path

    def local(self):
        return None

    def peer(self):
        return self

    def canpush(self):
        return True

    def close(self):
        try:
            reqs, sent, recv = (
                self._urlopener.requestscount,
                self._urlopener.sentbytescount,
                self._urlopener.receivedbytescount,
            )
        except AttributeError:
            return
        self.ui.note(
            _(
                b'(sent %d HTTP requests and %d bytes; '
                b'received %d bytes in responses)\n'
            )
            % (reqs, sent, recv)
        )

    # End of ipeerconnection interface.

    # Begin of ipeercommands interface.

    def capabilities(self):
        return self._caps

    # End of ipeercommands interface.

    def _callstream(self, cmd, _compressible=False, **args):
        args = pycompat.byteskwargs(args)

        req, cu, qs = makev1commandrequest(
            self.ui,
            self._requestbuilder,
            self._caps,
            self.capable,
            self._url,
            cmd,
            args,
        )

        resp = sendrequest(self.ui, self._urlopener, req)

        self._url, ct, resp = parsev1commandresponse(
            self.ui, self._url, cu, qs, resp, _compressible
        )

        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(b'unbundle')
        try:
            types = types.split(b',')
        except AttributeError:
            # servers older than d1b16a746db6 will send 'unbundle' as a
            # boolean capability. They only support headerless/uncompressed
            # bundles.
            types = [b""]
        for x in types:
            if x in bundle2.bundletypes:
                type = x
                break

        tempname = bundle2.writebundle(self.ui, cg, None, type)
        fp = httpconnection.httpsendfile(self.ui, tempname, b"rb")
        headers = {'Content-Type': 'application/mercurial-0.1'}

        try:
            r = self._call(cmd, data=fp, headers=headers, **args)
            vals = r.split(b'\n', 1)
            if len(vals) < 2:
                raise error.ResponseError(_(b"unexpected response:"), r)
            return vals
        except urlerr.httperror:
            # Catch and re-raise these so we don't try and treat them
            # like generic socket errors. They lack any values in
            # .args on Python 3 which breaks our socket.error block.
            raise
        except socket.error as err:
            if err.args[0] in (errno.ECONNRESET, errno.EPIPE):
                raise error.Abort(_(b'push failed: %s') % err.args[1])
            raise error.Abort(err.args[1])
        finally:
            fp.close()
            os.unlink(tempname)

    def _calltwowaystream(self, cmd, fp, **args):
        filename = None
        try:
            # dump bundle to disk
            fd, filename = pycompat.mkstemp(prefix=b"hg-bundle-", suffix=b".hg")
            with os.fdopen(fd, "wb") as fh:
                d = fp.read(4096)
                while d:
                    fh.write(d)
                    d = fp.read(4096)
            # start http push
            with httpconnection.httpsendfile(self.ui, filename, b"rb") as fp_:
                headers = {'Content-Type': 'application/mercurial-0.1'}
                return self._callstream(cmd, data=fp_, headers=headers, **args)
        finally:
            if filename is not None:
                os.unlink(filename)

    def _callcompressable(self, cmd, **args):
        return self._callstream(cmd, _compressible=True, **args)

    def _abort(self, exception):
        raise exception


class queuedcommandfuture(pycompat.futures.Future):
    """Wraps result() on command futures to trigger submission on call."""

    def result(self, timeout=None):
        if self.done():
            return pycompat.futures.Future.result(self, timeout)

        self._peerexecutor.sendcommands()

        # sendcommands() will restore the original __class__ and self.result
        # will resolve to Future.result.
        return self.result(timeout)


def performhandshake(ui, url, opener, requestbuilder):
    # The handshake is a request to the capabilities command.

    caps = None

    def capable(x):
        raise error.ProgrammingError(b'should not be called')

    args = {}

    req, requrl, qs = makev1commandrequest(
        ui, requestbuilder, caps, capable, url, b'capabilities', args
    )
    resp = sendrequest(ui, opener, req)

    # The server may redirect us to the repo root, stripping the
    # ?cmd=capabilities query string from the URL. The server would likely
    # return HTML in this case and ``parsev1commandresponse()`` would raise.
    # We catch this special case and re-issue the capabilities request against
    # the new URL.
    #
    # We should ideally not do this, as a redirect that drops the query
    # string from the URL is arguably a server bug. (Garbage in, garbage out).
    # However,  Mercurial clients for several years appeared to handle this
    # issue without behavior degradation. And according to issue 5860, it may
    # be a longstanding bug in some server implementations. So we allow a
    # redirect that drops the query string to "just work."
    try:
        respurl, ct, resp = parsev1commandresponse(
            ui, url, requrl, qs, resp, compressible=False
        )
    except RedirectedRepoError as e:
        req, requrl, qs = makev1commandrequest(
            ui, requestbuilder, caps, capable, e.respurl, b'capabilities', args
        )
        resp = sendrequest(ui, opener, req)
        respurl, ct, resp = parsev1commandresponse(
            ui, url, requrl, qs, resp, compressible=False
        )

    try:
        rawdata = resp.read()
    finally:
        resp.close()

    if not ct.startswith(b'application/mercurial-'):
        raise error.ProgrammingError(b'unexpected content-type: %s' % ct)

    info = {b'v1capabilities': set(rawdata.split())}

    return respurl, info


def makepeer(ui, path, opener=None, requestbuilder=urlreq.request):
    """Construct an appropriate HTTP peer instance.

    ``opener`` is an ``url.opener`` that should be used to establish
    connections, perform HTTP requests.

    ``requestbuilder`` is the type used for constructing HTTP requests.
    It exists as an argument so extensions can override the default.
    """
    u = urlutil.url(path)
    if u.query or u.fragment:
        raise error.Abort(
            _(b'unsupported URL component: "%s"') % (u.query or u.fragment)
        )

    # urllib cannot handle URLs with embedded user or passwd.
    url, authinfo = u.authinfo()
    ui.debug(b'using %s\n' % url)

    opener = opener or urlmod.opener(ui, authinfo)

    respurl, info = performhandshake(ui, url, opener, requestbuilder)

    return httppeer(
        ui, path, respurl, opener, requestbuilder, info[b'v1capabilities']
    )


def instance(ui, path, create, intents=None, createopts=None):
    if create:
        raise error.Abort(_(b'cannot create new http repository'))
    try:
        if path.startswith(b'https:') and not urlmod.has_https:
            raise error.Abort(
                _(b'Python support for SSL and HTTPS is not installed')
            )

        inst = makepeer(ui, path)

        return inst
    except error.RepoError as httpexception:
        try:
            r = statichttprepo.instance(ui, b"static-" + path, create)
            ui.note(_(b'(falling back to static-http)\n'))
            return r
        except error.RepoError:
            raise httpexception  # use the original http RepoError instead