debian: support building a single deb for multiple py3 versions
Around transitions from one python minor version to another (such as 3.7 to
3.8), the current packaging can be slightly problematic - it produces a
`control` file that requires that the version of `python3` that's installed be
exactly the one that was used on the build machine for the `mercurial` package,
by containing a line like:
Depends: sensible-utils, libc6 (>= 2.14), python3 (<< 3.8), python3 (>= 3.7~), python3:any (>= 3.5~)
This is because it "knows" we only built for v3.7, which is the current default
on my system. By building the native components for multiple versions, we can
make it produce a line like this, which is compatible with 3.7 AND 3.8:
Depends: sensible-utils, libc6 (>= 2.14), python3 (<< 3.9), python3 (>= 3.7~), python3:any (>= 3.5~)
This isn't *normally* required, so I'm not making it the default. For those that
receive their python3 and mercurial packages from their distro, and/or don't
have to worry about a situation where the team that manages the python3
installation isn't the same as the team that manages the mercurial installation,
this is probably not necessary.
I chose the names `DEB_HG_*` because `DEB_*` is passed through `debuild`
automatically (otherwise we'd have to explicitly allow the options through,
which is a nuisance), and the `HG` part is to make it clear that this isn't a
"standard" debian option that other packages might respect.
Test Plan:
1. "nothing changed":
- built a deb without these changes
- built a deb with these changes but everything at the default
- used diffoscope to compare, all differences were due to timestamps
2. "explicit is the same as implicit" (single version)
- built a deb with everything at the default
- built a deb with DEB_HG_PYTHON_VERSIONS=3.7
- used diffoscope to compare, all differences were due to timestamps
3. "explicit is the same as implicit" (multi version)
- built a deb with DEB_HG_MULTI_VERSION=1
- built a deb with DEB_HG_PYTHON_VERSIONS=3.7
- used diffoscope to compare, all differences were due to timestamps
4. (single version, 3.7) doesn't work with python3.8
- `/usr/bin/python3.7 /usr/bin/hg debuginstall` works
- `/usr/bin/python3.8 /usr/bin/hg debuginstall` crashes
5. (multi version, 3.7 + 3.8)
- `/usr/bin/python3.7 /usr/bin/hg debuginstall` works
- `/usr/bin/python3.8 /usr/bin/hg debuginstall` works
Differential Revision: https://phab.mercurial-scm.org/D8642
# commandserver.py - communicate with Mercurial's API over a pipe
#
# Copyright Matt Mackall <mpm@selenic.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 gc
import os
import random
import signal
import socket
import struct
import traceback
try:
import selectors
selectors.BaseSelector
except ImportError:
from .thirdparty import selectors2 as selectors
from .i18n import _
from .pycompat import getattr
from . import (
encoding,
error,
loggingutil,
pycompat,
repocache,
util,
vfs as vfsmod,
)
from .utils import (
cborutil,
procutil,
)
class channeledoutput(object):
"""
Write data to out in the following format:
data length (unsigned int),
data
"""
def __init__(self, out, channel):
self.out = out
self.channel = channel
@property
def name(self):
return b'<%c-channel>' % self.channel
def write(self, data):
if not data:
return
# single write() to guarantee the same atomicity as the underlying file
self.out.write(struct.pack(b'>cI', self.channel, len(data)) + data)
self.out.flush()
def __getattr__(self, attr):
if attr in ('isatty', 'fileno', 'tell', 'seek'):
raise AttributeError(attr)
return getattr(self.out, attr)
class channeledmessage(object):
"""
Write encoded message and metadata to out in the following format:
data length (unsigned int),
encoded message and metadata, as a flat key-value dict.
Each message should have 'type' attribute. Messages of unknown type
should be ignored.
"""
# teach ui that write() can take **opts
structured = True
def __init__(self, out, channel, encodename, encodefn):
self._cout = channeledoutput(out, channel)
self.encoding = encodename
self._encodefn = encodefn
def write(self, data, **opts):
opts = pycompat.byteskwargs(opts)
if data is not None:
opts[b'data'] = data
self._cout.write(self._encodefn(opts))
def __getattr__(self, attr):
return getattr(self._cout, attr)
class channeledinput(object):
"""
Read data from in_.
Requests for input are written to out in the following format:
channel identifier - 'I' for plain input, 'L' line based (1 byte)
how many bytes to send at most (unsigned int),
The client replies with:
data length (unsigned int), 0 meaning EOF
data
"""
maxchunksize = 4 * 1024
def __init__(self, in_, out, channel):
self.in_ = in_
self.out = out
self.channel = channel
@property
def name(self):
return b'<%c-channel>' % self.channel
def read(self, size=-1):
if size < 0:
# if we need to consume all the clients input, ask for 4k chunks
# so the pipe doesn't fill up risking a deadlock
size = self.maxchunksize
s = self._read(size, self.channel)
buf = s
while s:
s = self._read(size, self.channel)
buf += s
return buf
else:
return self._read(size, self.channel)
def _read(self, size, channel):
if not size:
return b''
assert size > 0
# tell the client we need at most size bytes
self.out.write(struct.pack(b'>cI', channel, size))
self.out.flush()
length = self.in_.read(4)
length = struct.unpack(b'>I', length)[0]
if not length:
return b''
else:
return self.in_.read(length)
def readline(self, size=-1):
if size < 0:
size = self.maxchunksize
s = self._read(size, b'L')
buf = s
# keep asking for more until there's either no more or
# we got a full line
while s and not s.endswith(b'\n'):
s = self._read(size, b'L')
buf += s
return buf
else:
return self._read(size, b'L')
def __iter__(self):
return self
def next(self):
l = self.readline()
if not l:
raise StopIteration
return l
__next__ = next
def __getattr__(self, attr):
if attr in ('isatty', 'fileno', 'tell', 'seek'):
raise AttributeError(attr)
return getattr(self.in_, attr)
_messageencoders = {
b'cbor': lambda v: b''.join(cborutil.streamencode(v)),
}
def _selectmessageencoder(ui):
# experimental config: cmdserver.message-encodings
encnames = ui.configlist(b'cmdserver', b'message-encodings')
for n in encnames:
f = _messageencoders.get(n)
if f:
return n, f
raise error.Abort(
b'no supported message encodings: %s' % b' '.join(encnames)
)
class server(object):
"""
Listens for commands on fin, runs them and writes the output on a channel
based stream to fout.
"""
def __init__(self, ui, repo, fin, fout, prereposetups=None):
self.cwd = encoding.getcwd()
if repo:
# the ui here is really the repo ui so take its baseui so we don't
# end up with its local configuration
self.ui = repo.baseui
self.repo = repo
self.repoui = repo.ui
else:
self.ui = ui
self.repo = self.repoui = None
self._prereposetups = prereposetups
self.cdebug = channeledoutput(fout, b'd')
self.cerr = channeledoutput(fout, b'e')
self.cout = channeledoutput(fout, b'o')
self.cin = channeledinput(fin, fout, b'I')
self.cresult = channeledoutput(fout, b'r')
if self.ui.config(b'cmdserver', b'log') == b'-':
# switch log stream of server's ui to the 'd' (debug) channel
# (don't touch repo.ui as its lifetime is longer than the server)
self.ui = self.ui.copy()
setuplogging(self.ui, repo=None, fp=self.cdebug)
# TODO: add this to help/config.txt when stabilized
# ``channel``
# Use separate channel for structured output. (Command-server only)
self.cmsg = None
if ui.config(b'ui', b'message-output') == b'channel':
encname, encfn = _selectmessageencoder(ui)
self.cmsg = channeledmessage(fout, b'm', encname, encfn)
self.client = fin
def cleanup(self):
"""release and restore resources taken during server session"""
def _read(self, size):
if not size:
return b''
data = self.client.read(size)
# is the other end closed?
if not data:
raise EOFError
return data
def _readstr(self):
"""read a string from the channel
format:
data length (uint32), data
"""
length = struct.unpack(b'>I', self._read(4))[0]
if not length:
return b''
return self._read(length)
def _readlist(self):
"""read a list of NULL separated strings from the channel"""
s = self._readstr()
if s:
return s.split(b'\0')
else:
return []
def runcommand(self):
""" reads a list of \0 terminated arguments, executes
and writes the return code to the result channel """
from . import dispatch # avoid cycle
args = self._readlist()
# copy the uis so changes (e.g. --config or --verbose) don't
# persist between requests
copiedui = self.ui.copy()
uis = [copiedui]
if self.repo:
self.repo.baseui = copiedui
# clone ui without using ui.copy because this is protected
repoui = self.repoui.__class__(self.repoui)
repoui.copy = copiedui.copy # redo copy protection
uis.append(repoui)
self.repo.ui = self.repo.dirstate._ui = repoui
self.repo.invalidateall()
for ui in uis:
ui.resetstate()
# any kind of interaction must use server channels, but chg may
# replace channels by fully functional tty files. so nontty is
# enforced only if cin is a channel.
if not util.safehasattr(self.cin, b'fileno'):
ui.setconfig(b'ui', b'nontty', b'true', b'commandserver')
req = dispatch.request(
args[:],
copiedui,
self.repo,
self.cin,
self.cout,
self.cerr,
self.cmsg,
prereposetups=self._prereposetups,
)
try:
ret = dispatch.dispatch(req) & 255
self.cresult.write(struct.pack(b'>i', int(ret)))
finally:
# restore old cwd
if b'--cwd' in args:
os.chdir(self.cwd)
def getencoding(self):
""" writes the current encoding to the result channel """
self.cresult.write(encoding.encoding)
def serveone(self):
cmd = self.client.readline()[:-1]
if cmd:
handler = self.capabilities.get(cmd)
if handler:
handler(self)
else:
# clients are expected to check what commands are supported by
# looking at the servers capabilities
raise error.Abort(_(b'unknown command %s') % cmd)
return cmd != b''
capabilities = {b'runcommand': runcommand, b'getencoding': getencoding}
def serve(self):
hellomsg = b'capabilities: ' + b' '.join(sorted(self.capabilities))
hellomsg += b'\n'
hellomsg += b'encoding: ' + encoding.encoding
hellomsg += b'\n'
if self.cmsg:
hellomsg += b'message-encoding: %s\n' % self.cmsg.encoding
hellomsg += b'pid: %d' % procutil.getpid()
if util.safehasattr(os, b'getpgid'):
hellomsg += b'\n'
hellomsg += b'pgid: %d' % os.getpgid(0)
# write the hello msg in -one- chunk
self.cout.write(hellomsg)
try:
while self.serveone():
pass
except EOFError:
# we'll get here if the client disconnected while we were reading
# its request
return 1
return 0
def setuplogging(ui, repo=None, fp=None):
"""Set up server logging facility
If cmdserver.log is '-', log messages will be sent to the given fp.
It should be the 'd' channel while a client is connected, and otherwise
is the stderr of the server process.
"""
# developer config: cmdserver.log
logpath = ui.config(b'cmdserver', b'log')
if not logpath:
return
# developer config: cmdserver.track-log
tracked = set(ui.configlist(b'cmdserver', b'track-log'))
if logpath == b'-' and fp:
logger = loggingutil.fileobjectlogger(fp, tracked)
elif logpath == b'-':
logger = loggingutil.fileobjectlogger(ui.ferr, tracked)
else:
logpath = os.path.abspath(util.expandpath(logpath))
# developer config: cmdserver.max-log-files
maxfiles = ui.configint(b'cmdserver', b'max-log-files')
# developer config: cmdserver.max-log-size
maxsize = ui.configbytes(b'cmdserver', b'max-log-size')
vfs = vfsmod.vfs(os.path.dirname(logpath))
logger = loggingutil.filelogger(
vfs,
os.path.basename(logpath),
tracked,
maxfiles=maxfiles,
maxsize=maxsize,
)
targetuis = {ui}
if repo:
targetuis.add(repo.baseui)
targetuis.add(repo.ui)
for u in targetuis:
u.setlogger(b'cmdserver', logger)
class pipeservice(object):
def __init__(self, ui, repo, opts):
self.ui = ui
self.repo = repo
def init(self):
pass
def run(self):
ui = self.ui
# redirect stdio to null device so that broken extensions or in-process
# hooks will never cause corruption of channel protocol.
with ui.protectedfinout() as (fin, fout):
sv = server(ui, self.repo, fin, fout)
try:
return sv.serve()
finally:
sv.cleanup()
def _initworkerprocess():
# use a different process group from the master process, in order to:
# 1. make the current process group no longer "orphaned" (because the
# parent of this process is in a different process group while
# remains in a same session)
# according to POSIX 2.2.2.52, orphaned process group will ignore
# terminal-generated stop signals like SIGTSTP (Ctrl+Z), which will
# cause trouble for things like ncurses.
# 2. the client can use kill(-pgid, sig) to simulate terminal-generated
# SIGINT (Ctrl+C) and process-exit-generated SIGHUP. our child
# processes like ssh will be killed properly, without affecting
# unrelated processes.
os.setpgid(0, 0)
# change random state otherwise forked request handlers would have a
# same state inherited from parent.
random.seed()
def _serverequest(ui, repo, conn, createcmdserver, prereposetups):
fin = conn.makefile('rb')
fout = conn.makefile('wb')
sv = None
try:
sv = createcmdserver(repo, conn, fin, fout, prereposetups)
try:
sv.serve()
# handle exceptions that may be raised by command server. most of
# known exceptions are caught by dispatch.
except error.Abort as inst:
ui.error(_(b'abort: %s\n') % inst)
except IOError as inst:
if inst.errno != errno.EPIPE:
raise
except KeyboardInterrupt:
pass
finally:
sv.cleanup()
except: # re-raises
# also write traceback to error channel. otherwise client cannot
# see it because it is written to server's stderr by default.
if sv:
cerr = sv.cerr
else:
cerr = channeledoutput(fout, b'e')
cerr.write(encoding.strtolocal(traceback.format_exc()))
raise
finally:
fin.close()
try:
fout.close() # implicit flush() may cause another EPIPE
except IOError as inst:
if inst.errno != errno.EPIPE:
raise
class unixservicehandler(object):
"""Set of pluggable operations for unix-mode services
Almost all methods except for createcmdserver() are called in the main
process. You can't pass mutable resource back from createcmdserver().
"""
pollinterval = None
def __init__(self, ui):
self.ui = ui
def bindsocket(self, sock, address):
util.bindunixsocket(sock, address)
sock.listen(socket.SOMAXCONN)
self.ui.status(_(b'listening at %s\n') % address)
self.ui.flush() # avoid buffering of status message
def unlinksocket(self, address):
os.unlink(address)
def shouldexit(self):
"""True if server should shut down; checked per pollinterval"""
return False
def newconnection(self):
"""Called when main process notices new connection"""
def createcmdserver(self, repo, conn, fin, fout, prereposetups):
"""Create new command server instance; called in the process that
serves for the current connection"""
return server(self.ui, repo, fin, fout, prereposetups)
class unixforkingservice(object):
"""
Listens on unix domain socket and forks server per connection
"""
def __init__(self, ui, repo, opts, handler=None):
self.ui = ui
self.repo = repo
self.address = opts[b'address']
if not util.safehasattr(socket, b'AF_UNIX'):
raise error.Abort(_(b'unsupported platform'))
if not self.address:
raise error.Abort(_(b'no socket path specified with --address'))
self._servicehandler = handler or unixservicehandler(ui)
self._sock = None
self._mainipc = None
self._workeripc = None
self._oldsigchldhandler = None
self._workerpids = set() # updated by signal handler; do not iterate
self._socketunlinked = None
# experimental config: cmdserver.max-repo-cache
maxlen = ui.configint(b'cmdserver', b'max-repo-cache')
if maxlen < 0:
raise error.Abort(_(b'negative max-repo-cache size not allowed'))
self._repoloader = repocache.repoloader(ui, maxlen)
# attempt to avoid crash in CoreFoundation when using chg after fix in
# a89381e04c58
if pycompat.isdarwin:
procutil.gui()
def init(self):
self._sock = socket.socket(socket.AF_UNIX)
# IPC channel from many workers to one main process; this is actually
# a uni-directional pipe, but is backed by a DGRAM socket so each
# message can be easily separated.
o = socket.socketpair(socket.AF_UNIX, socket.SOCK_DGRAM)
self._mainipc, self._workeripc = o
self._servicehandler.bindsocket(self._sock, self.address)
if util.safehasattr(procutil, b'unblocksignal'):
procutil.unblocksignal(signal.SIGCHLD)
o = signal.signal(signal.SIGCHLD, self._sigchldhandler)
self._oldsigchldhandler = o
self._socketunlinked = False
self._repoloader.start()
def _unlinksocket(self):
if not self._socketunlinked:
self._servicehandler.unlinksocket(self.address)
self._socketunlinked = True
def _cleanup(self):
signal.signal(signal.SIGCHLD, self._oldsigchldhandler)
self._sock.close()
self._mainipc.close()
self._workeripc.close()
self._unlinksocket()
self._repoloader.stop()
# don't kill child processes as they have active clients, just wait
self._reapworkers(0)
def run(self):
try:
self._mainloop()
finally:
self._cleanup()
def _mainloop(self):
exiting = False
h = self._servicehandler
selector = selectors.DefaultSelector()
selector.register(
self._sock, selectors.EVENT_READ, self._acceptnewconnection
)
selector.register(
self._mainipc, selectors.EVENT_READ, self._handlemainipc
)
while True:
if not exiting and h.shouldexit():
# clients can no longer connect() to the domain socket, so
# we stop queuing new requests.
# for requests that are queued (connect()-ed, but haven't been
# accept()-ed), handle them before exit. otherwise, clients
# waiting for recv() will receive ECONNRESET.
self._unlinksocket()
exiting = True
try:
events = selector.select(timeout=h.pollinterval)
except OSError as inst:
# selectors2 raises ETIMEDOUT if timeout exceeded while
# handling signal interrupt. That's probably wrong, but
# we can easily get around it.
if inst.errno != errno.ETIMEDOUT:
raise
events = []
if not events:
# only exit if we completed all queued requests
if exiting:
break
continue
for key, _mask in events:
key.data(key.fileobj, selector)
selector.close()
def _acceptnewconnection(self, sock, selector):
h = self._servicehandler
try:
conn, _addr = sock.accept()
except socket.error as inst:
if inst.args[0] == errno.EINTR:
return
raise
# Future improvement: On Python 3.7, maybe gc.freeze() can be used
# to prevent COW memory from being touched by GC.
# https://instagram-engineering.com/
# copy-on-write-friendly-python-garbage-collection-ad6ed5233ddf
pid = os.fork()
if pid:
try:
self.ui.log(
b'cmdserver', b'forked worker process (pid=%d)\n', pid
)
self._workerpids.add(pid)
h.newconnection()
finally:
conn.close() # release handle in parent process
else:
try:
selector.close()
sock.close()
self._mainipc.close()
self._runworker(conn)
conn.close()
self._workeripc.close()
os._exit(0)
except: # never return, hence no re-raises
try:
self.ui.traceback(force=True)
finally:
os._exit(255)
def _handlemainipc(self, sock, selector):
"""Process messages sent from a worker"""
try:
path = sock.recv(32768) # large enough to receive path
except socket.error as inst:
if inst.args[0] == errno.EINTR:
return
raise
self._repoloader.load(path)
def _sigchldhandler(self, signal, frame):
self._reapworkers(os.WNOHANG)
def _reapworkers(self, options):
while self._workerpids:
try:
pid, _status = os.waitpid(-1, options)
except OSError as inst:
if inst.errno == errno.EINTR:
continue
if inst.errno != errno.ECHILD:
raise
# no child processes at all (reaped by other waitpid()?)
self._workerpids.clear()
return
if pid == 0:
# no waitable child processes
return
self.ui.log(b'cmdserver', b'worker process exited (pid=%d)\n', pid)
self._workerpids.discard(pid)
def _runworker(self, conn):
signal.signal(signal.SIGCHLD, self._oldsigchldhandler)
_initworkerprocess()
h = self._servicehandler
try:
_serverequest(
self.ui,
self.repo,
conn,
h.createcmdserver,
prereposetups=[self._reposetup],
)
finally:
gc.collect() # trigger __del__ since worker process uses os._exit
def _reposetup(self, ui, repo):
if not repo.local():
return
class unixcmdserverrepo(repo.__class__):
def close(self):
super(unixcmdserverrepo, self).close()
try:
self._cmdserveripc.send(self.root)
except socket.error:
self.ui.log(
b'cmdserver', b'failed to send repo root to master\n'
)
repo.__class__ = unixcmdserverrepo
repo._cmdserveripc = self._workeripc
cachedrepo = self._repoloader.get(repo.root)
if cachedrepo is None:
return
repo.ui.log(b'repocache', b'repo from cache: %s\n', repo.root)
repocache.copycache(cachedrepo, repo)