Mercurial > hg
view mercurial/httppeer.py @ 35569:964212780daf
rust: implementation of `hg`
This commit provides a mostly-working implementation of the
`hg` script in Rust along with scaffolding to support Rust in
the repository.
If you are familiar with Rust, the contents of the added rust/
directory should be pretty straightforward. We create an "hgcli"
package that implements a binary application to run Mercurial.
The output of this package is an "hg" binary.
Our Rust `hg` (henceforth "rhg") essentially is a port of the existing
`hg` Python script. The main difference is the creation of the embedded
CPython interpreter is handled by the binary itself instead of relying
on the shebang. In that sense, rhg is more similar to the "exe wrapper"
we currently use on Windows. However, unlike the exe wrapper, rhg does
not call the `hg` Python script. Instead, it uses the CPython APIs to
import mercurial modules and call appropriate functions. The amount of
code here is surprisingly small.
It is my intent to replace the existing C-based exe wrapper with rhg.
Preferably in the next Mercurial release. This should be achievable -
at least for some Mercurial distributions. The future/timeline for
rhg on other platforms is less clear. We already ship a hg.exe on
Windows. So if we get the quirks with Rust worked out, shipping a
Rust-based hg.exe should hopefully not be too contentious.
Now onto the implementation.
We're using python27-sys and the cpython crates for talking to the
CPython API. We currently don't use too much functionality of the
cpython crate and could have probably cut it out. However, it does
provide a reasonable abstraction over unsafe {} CPython function
calls. While we still have our fair share of those, at least we're
not dealing with too much refcounting, error checking, etc. So I
think the use of the cpython crate is justified. Plus, there is
not-yet-implemented functionality that could benefit from cpython. I
see our use of this crate only increasing.
The cpython and python27-sys crates are not without their issues.
The cpython crate didn't seem to account for the embedding use case
in its design. Instead, it seems to assume that you are building
a Python extension. It is making some questionable decisions around
certain CPython APIs. For example, it insists that
PyEval_ThreadsInitialized() is called and that the Python code
likely isn't the main thread in the underlying application. It
is also missing some functionality that is important for embedded
use cases (such as exporting the path to the Python interpreter
from its build script). After spending several hours trying to
wrangle python27-sys and cpython, I gave up and forked the project
on GitHub. Our Cargo.toml tracks this fork. I'm optimistic that
the upstream project will accept our contributions and we can
eventually unfork.
There is a non-trivial amount of code in our custom Cargo build
script. Our build.rs (which is called as part of building the hgcli
crate):
* Validates that the Python interpreter that was detected by the
python27-sys crate provides a shared library (we only support
shared library linking at this time - although this restriction
could be loosened).
* Validates that the Python is built with UCS-4 support. This ensures
maximum Unicode compatibility.
* Exports variables to the crate build allowing the built crate to e.g.
find the path to the Python interpreter.
The produced rhg should be considered alpha quality. There are several
known deficiencies. Many of these are documented with inline TODOs.
Probably the biggest limitation of rhg is that it assumes it is
running from the ./rust/target/<target> directory of a source
distribution. So, rhg is currently not very practical for real-world
use. But, if you can `cargo build` it, running the binary *should*
yield a working Mercurial CLI.
In order to support using rhg with the test harness, we needed to hack
up run-tests.py so the path to Mercurial's Python files is set properly.
The change is extremely hacky and is only intended to be a stop-gap
until the test harness gains first-class support for installing rhg.
This will likely occur after we support running rhg outside the
source directory.
Despite its officially alpha quality, rhg copes extremely well with
the test harness (at least on Linux). Using
`run-tests.py --with-hg ../rust/target/debug/hg`, I only encounter
the following failures:
* test-run-tests.t -- Warnings emitted about using an unexpected
Mercurial library. This is due to the hacky nature of setting the
Python directory when run-tests.py detected rhg.
* test-devel-warnings.t -- Expected stack trace missing frame for `hg`
(This is expected since we no longer have an `hg` script!)
* test-convert.t -- Test running `$PYTHON "$BINDIR"/hg`, which obviously
assumes `hg` is a Python script.
* test-merge-tools.t -- Same assumption about `hg` being executable with
Python.
* test-http-bad-server.t -- Seeing exit code 255 instead of 1 around
line 358.
* test-blackbox.t -- Exit code 255 instead of 1.
* test-basic.t -- Exit code 255 instead of 1.
It certainly looks like we have a bug around exit code handling. I
don't think it is severe enough to hold up review and landing of this
initial implementation. Perfect is the enemy of good.
Differential Revision: https://phab.mercurial-scm.org/D1581
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 10 Jan 2018 08:53:22 -0800 |
parents | 98bc4c43f570 |
children | 5a7906ed78d4 |
line wrap: on
line source
# httppeer.py - HTTP repository proxy classes for mercurial # # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> # Copyright 2006 Vadim Gelfer <vadim.gelfer@gmail.com> # # 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 import tempfile from .i18n import _ from .node import nullid from . import ( bundle2, error, httpconnection, pycompat, statichttprepo, url, util, wireproto, ) 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 % r'000') - len(': \r\n') result = [] n = 0 for i in xrange(0, len(value), valuelen): n += 1 result.append((fmt % str(n), pycompat.strurl(value[i:i + valuelen]))) return result def _wraphttpresponse(resp): """Wrap an HTTPResponse with common error handlers. This ensures that any I/O from any consumer raises the appropriate error and messaging. """ origread = resp.read class readerproxy(resp.__class__): def read(self, size=None): try: return origread(size) except httplib.IncompleteRead as e: # e.expected is an integer if length known or None otherwise. if e.expected: msg = _('HTTP request error (incomplete response; ' 'expected %d bytes got %d)') % (e.expected, len(e.partial)) else: msg = _('HTTP request error (incomplete response)') raise error.PeerTransportError( msg, hint=_('this may be an intermittent network failure; ' 'if the error persists, consider contacting the ' 'network or server operator')) except httplib.HTTPException as e: raise error.PeerTransportError( _('HTTP request error (%s)') % e, hint=_('this may be an intermittent network failure; ' 'if the error persists, consider contacting the ' 'network or server operator')) resp.__class__ = readerproxy class _multifile(object): def __init__(self, *fileobjs): for f in fileobjs: if not util.safehasattr(f, 'length'): raise ValueError( '_multifile only supports file objects that ' '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 ''.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 ''.join(parts) def seek(self, offset, whence=os.SEEK_SET): if whence != os.SEEK_SET: raise NotImplementedError( '_multifile does not support anything other' ' than os.SEEK_SET for whence on seek()') if offset != 0: raise NotImplementedError( '_multifile only supports seeking to start, but that ' 'could be fixed if you need it') for f in self._fileobjs: f.seek(0) self._index = 0 class httppeer(wireproto.wirepeer): def __init__(self, ui, path): self._path = path self._caps = None self._urlopener = None self._requestbuilder = None u = util.url(path) if u.query or u.fragment: raise error.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 ui.debug('using %s\n' % self._url) self._urlopener = url.opener(ui, authinfo) self._requestbuilder = urlreq.request def __del__(self): urlopener = getattr(self, '_urlopener', None) if urlopener: for h in urlopener.handlers: h.close() getattr(h, "close_all", lambda: None)() # Begin of _basepeer interface. @util.propertycache def ui(self): return self._ui def url(self): return self._path def local(self): return None def peer(self): return self def canpush(self): return True def close(self): pass # End of _basepeer interface. # Begin of _basewirepeer interface. def capabilities(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 # End of _basewirepeer interface. # look up capabilities only when needed def _fetchcaps(self): self._caps = set(self._call('capabilities').split()) def _callstream(self, cmd, _compressible=False, **args): args = pycompat.byteskwargs(args) if cmd == 'pushkey': args['data'] = '' data = args.pop('data', None) headers = args.pop('headers', {}) self.ui.debug("sending %s command\n" % cmd) q = [('cmd', cmd)] headersize = 0 varyheaders = [] # 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 = self._caps is not None and 'httppostargs' in self._caps 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[r'X-HgArgs-Post'] = len(strargs) else: if len(args) > 0: httpheader = self.capable('httpheader') if httpheader: headersize = int(httpheader.split(',', 1)[0]) if headersize > 0: # The headers can typically carry more data than the URL. encargs = urlreq.urlencode(sorted(args.items())) for header, value in encodevalueinheaders(encargs, 'X-HgArg', headersize): headers[header] = value varyheaders.append(header) else: q += sorted(args.items()) qs = '?%s' % urlreq.urlencode(q) cu = "%s%s" % (self._url, qs) size = 0 if util.safehasattr(data, 'length'): size = data.length elif data is not None: size = len(data) if size and self.ui.configbool('ui', 'usehttp2'): headers[r'Expect'] = r'100-Continue' headers[r'X-HgHttp2'] = r'1' if data is not None and r'Content-Type' not in headers: headers[r'Content-Type'] = r'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. protoparams = [] mediatypes = set() if self._caps is not None: mt = self.capable('httpmediatype') if mt: protoparams.append('0.1') mediatypes = set(mt.split(',')) if '0.2tx' in mediatypes: protoparams.append('0.2') if '0.2tx' in mediatypes and self.capable('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.append('comp=%s' % ','.join(comps)) if protoparams: protoheaders = encodevalueinheaders(' '.join(protoparams), 'X-HgProto', headersize or 1024) for header, value in protoheaders: headers[header] = value varyheaders.append(header) if varyheaders: headers[r'Vary'] = r','.join(varyheaders) req = self._requestbuilder(pycompat.strurl(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 urlerr.httperror as inst: if inst.code == 401: raise error.Abort(_('authorization failed')) raise except httplib.HTTPException as inst: self.ui.debug('http error while sending %s command\n' % cmd) self.ui.traceback() raise IOError(None, inst) # Insert error handlers for common I/O failures. _wraphttpresponse(resp) # record the url we got redirected to resp_url = pycompat.bytesurl(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 = pycompat.bytesurl(resp.getheader(r'content-type', r'')) except AttributeError: proto = pycompat.bytesurl(resp.headers.get(r'content-type', r'')) 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') and not resp.headers.get('content-length')) 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(1024))) 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)) # TODO consider switching to a decompression reader that uses # generators. if version_info == (0, 1): if _compressible: return util.compengines['zlib'].decompressorreader(resp) return resp elif version_info == (0, 2): # application/mercurial-0.2 always identifies the compression # engine in the payload header. elen = struct.unpack('B', resp.read(1))[0] ename = resp.read(elen) engine = util.compengines.forwiretype(ename) return engine.decompressorreader(resp) else: raise error.RepoError(_("'%s' uses newer protocol %s") % (safeurl, version)) if _compressible: return util.compengines['zlib'].decompressorreader(resp) 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 bundle2.bundletypes: type = x break tempname = bundle2.writebundle(self.ui, cg, None, type) fp = httpconnection.httpsendfile(self.ui, tempname, "rb") headers = {'Content-Type': 'application/mercurial-0.1'} 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 as err: if err.args[0] in (errno.ECONNRESET, errno.EPIPE): raise error.Abort(_('push failed: %s') % err.args[1]) raise error.Abort(err.args[1]) finally: fp.close() os.unlink(tempname) def _calltwowaystream(self, cmd, fp, **args): fh = None fp_ = None filename = None try: # dump bundle to disk fd, filename = tempfile.mkstemp(prefix="hg-bundle-", suffix=".hg") fh = os.fdopen(fd, pycompat.sysstr("wb")) d = fp.read(4096) while d: fh.write(d) d = fp.read(4096) fh.close() # start http push fp_ = httpconnection.httpsendfile(self.ui, filename, "rb") headers = {'Content-Type': 'application/mercurial-0.1'} return self._callstream(cmd, data=fp_, headers=headers, **args) finally: if fp_ is not None: fp_.close() if fh is not None: fh.close() os.unlink(filename) def _callcompressable(self, cmd, **args): return self._callstream(cmd, _compressible=True, **args) def _abort(self, exception): raise exception class httpspeer(httppeer): def __init__(self, ui, path): if not url.has_https: raise error.Abort(_('Python support for SSL and HTTPS ' 'is not installed')) httppeer.__init__(self, ui, path) def instance(ui, path, create): if create: raise error.Abort(_('cannot create new http repository')) try: if path.startswith('https:'): inst = httpspeer(ui, path) else: inst = httppeer(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 as 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