view mercurial/statichttprepo.py @ 14093:ce99d887585f

httprepo: long arguments support (issue2126)

Send the command arguments in the HTTP headers. The command is still part
of the URL. If the server does not have the 'httpheader' capability, the
client will send the command arguments in the URL as it did previously.

Web servers typically allow more data to be placed within the headers than
in the URL, so this approach will:
- Avoid HTTP errors due to using a URL that is too large.
- Allow Mercurial to implement a more efficient wire protocol.

An alternate approach is to send the arguments as part of the request body.
This approach has been rejected because it requires the use of POST
requests, so it would break any existing configuration that relies on the
request type for authentication or caching.

Extensibility:
- The header size is provided by the server, which makes it possible to
  introduce an hgrc setting for it.
- The client ignores the capability value after the first comma, which
  allows more information to be included in the future.

# statichttprepo.py - simple http repository class for mercurial
#
# This provides read-only repo access to repositories exported via static http
#
# Copyright 2005-2007 Matt Mackall <[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 i18n import _
import changelog, byterange, url, error
import localrepo, manifest, util, scmutil, store
import urllib, urllib2, errno

class httprangereader(object):
    def __init__(self, url, opener):
        # we assume opener has HTTPRangeHandler
        self.url = url
        self.pos = 0
        self.opener = opener
        self.name = url
    def seek(self, pos):
        self.pos = pos
    def read(self, bytes=None):
        req = urllib2.Request(self.url)
        end = ''
        if bytes:
            end = self.pos + bytes - 1
        req.add_header('Range', 'bytes=%d-%s' % (self.pos, end))

        try:
            f = self.opener.open(req)
            data = f.read()
            if hasattr(f, 'getcode'):
                # python 2.6+
                code = f.getcode()
            elif hasattr(f, 'code'):
                # undocumented attribute, seems to be set in 2.4 and 2.5
                code = f.code
            else:
                # Don't know how to check, hope for the best.
                code = 206
        except urllib2.HTTPError, inst:
            num = inst.code == 404 and errno.ENOENT or None
            raise IOError(num, inst)
        except urllib2.URLError, inst:
            raise IOError(None, inst.reason[1])

        if code == 200:
            # HTTPRangeHandler does nothing if remote does not support
            # Range headers and returns the full entity. Let's slice it.
            if bytes:
                data = data[self.pos:self.pos + bytes]
            else:
                data = data[self.pos:]
        elif bytes:
            data = data[:bytes]
        self.pos += len(data)
        return data
    def __iter__(self):
        return iter(self.read().splitlines(1))
    def close(self):
        pass

def build_opener(ui, authinfo):
    # urllib cannot handle URLs with embedded user or passwd
    urlopener = url.opener(ui, authinfo)
    urlopener.add_handler(byterange.HTTPRangeHandler())

    class statichttpopener(scmutil.abstractopener):
        def __init__(self, base):
            self.base = base

        def __call__(self, path, mode="r", atomictemp=None):
            if mode not in ('r', 'rb'):
                raise IOError('Permission denied')
            f = "/".join((self.base, urllib.quote(path)))
            return httprangereader(f, urlopener)

    return statichttpopener

class statichttprepository(localrepo.localrepository):
    def __init__(self, ui, path):
        self._url = path
        self.ui = ui

        self.root = path
        u = util.url(path.rstrip('/') + "/.hg")
        self.path, authinfo = u.authinfo()

        opener = build_opener(ui, authinfo)
        self.opener = opener(self.path)

        # find requirements
        try:
            requirements = self.opener("requires").read().splitlines()
        except IOError, inst:
            if inst.errno != errno.ENOENT:
                raise
            # check if it is a non-empty old-style repository
            try:
                fp = self.opener("00changelog.i")
                fp.read(1)
                fp.close()
            except IOError, inst:
                if inst.errno != errno.ENOENT:
                    raise
                # we do not care about empty old-style repositories here
                msg = _("'%s' does not appear to be an hg repository") % path
                raise error.RepoError(msg)
            requirements = []

        # check them
        for r in requirements:
            if r not in self.supported:
                raise error.RequirementError(
                        _("requirement '%s' not supported") % r)

        # setup store
        self.store = store.store(requirements, self.path, opener)
        self.spath = self.store.path
        self.sopener = self.store.opener
        self.sjoin = self.store.join

        self.manifest = manifest.manifest(self.sopener)
        self.changelog = changelog.changelog(self.sopener)
        self._tags = None
        self.nodetagscache = None
        self._branchcache = None
        self._branchcachetip = None
        self.encodepats = None
        self.decodepats = None
        self.capabilities = self.capabilities.difference(["pushkey"])

    def url(self):
        return self._url

    def local(self):
        return False

    def lock(self, wait=True):
        raise util.Abort(_('cannot lock static-http repository'))

def instance(ui, path, create):
    if create:
        raise util.Abort(_('cannot create new static-http repository'))
    return statichttprepository(ui, path[7:])