Mercurial > hg
view mercurial/commandserver.py @ 47072:4c041c71ec01
revlog: introduce an explicit tracking of what the revlog is about
Since the dawn of time, people have been forced to rely to lossy introspection
of the index filename to determine what the purpose and role of the revlog they
encounter is. This is hacky, error prone, inflexible, abstraction-leaky,
<insert-your-own-complaints-here>.
In f63299ee7e4d Raphaël introduced a new attribute to track this information:
`revlog_kind`. However it is initialized in an odd place and various instances
end up not having it set. In addition is only tracking some of the information
we end up having to introspect in various pieces of code.
So we add a new attribute that holds more data and is more strictly enforced.
This work is done in collaboration with Raphaël.
The `revlog_kind` one will be removed/adapted in the next changeset. We expect
to be able to clean up various existing piece of code and to simplify coming
work around the newer revlog format.
Differential Revision: https://phab.mercurial-scm.org/D10352
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Tue, 06 Apr 2021 05:20:24 +0200 |
parents | d4ba4d51f85f |
children | f38bf44e077f |
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# commandserver.py - communicate with Mercurial's API over a pipe # # Copyright Olivia Mackall <olivia@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): 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) 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 # If shutdown-on-interrupt is off, the default SIGINT handler is # removed so that client-server communication wouldn't be interrupted. # For example, 'runcommand' handler will issue three short read()s. # If one of the first two read()s were interrupted, the communication # channel would be left at dirty state and the subsequent request # wouldn't be parsed. So catching KeyboardInterrupt isn't enough. self._shutdown_on_interrupt = ui.configbool( b'cmdserver', b'shutdown-on-interrupt' ) self._old_inthandler = None if not self._shutdown_on_interrupt: self._old_inthandler = signal.signal(signal.SIGINT, signal.SIG_IGN) def cleanup(self): """release and restore resources taken during server session""" if not self._shutdown_on_interrupt: signal.signal(signal.SIGINT, self._old_inthandler) 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 _dispatchcommand(self, req): from . import dispatch # avoid cycle if self._shutdown_on_interrupt: # no need to restore SIGINT handler as it is unmodified. return dispatch.dispatch(req) try: signal.signal(signal.SIGINT, self._old_inthandler) return dispatch.dispatch(req) except error.SignalInterrupt: # propagate SIGBREAK, SIGHUP, or SIGTERM. raise except KeyboardInterrupt: # SIGINT may be received out of the try-except block of dispatch(), # so catch it as last ditch. Another KeyboardInterrupt may be # raised while handling exceptions here, but there's no way to # avoid that except for doing everything in C. pass finally: signal.signal(signal.SIGINT, signal.SIG_IGN) # On KeyboardInterrupt, print error message and exit *after* SIGINT # handler removed. req.ui.error(_(b'interrupted!\n')) return -1 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 = self._dispatchcommand(req) & 255 # If shutdown-on-interrupt is off, it's important to write the # result code *after* SIGINT handler removed. If the result code # were lost, the client wouldn't be able to continue processing. 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.message) 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)