view mercurial/commandserver.py @ 33390:32331f54930c

hgweb: re-implement followlines UI selection using buttons

This changeset attempts to solve two issues with the "followlines" UI in
hgweb. First the "followlines" action is currently not easily discoverable
(one has to hover on a line for some time, wait for the invite message to
appear and then perform some action). Second, it gets in the way of natural
line selection, especially in filerevision view.

This changeset introduces an additional markup element (a <button
class="btn-followlines">) alongside each content line of the view. This button
now holds events for line selection that were previously plugged onto content
lines directly. Consequently, there's no more action on content lines, hence
restoring the "natural line selection" behavior (solving the second problem).
These buttons are hidden by default and get displayed upon hover of content
lines; then upon hover of a button itself, a text inviting followlines section
shows up. This solves the first problem (discoverability) as we now have a
clear visual element indicating that "some action could be perform" (i.e. a
button) and that is self-documented.

In followlines.js, all event listeners are now attached to these <button>
elements. The custom "floating tooltip" element is dropped as <button>
elements are now self-documented through a "title" attribute that changes
depending on preceding actions (selection started or not, in particular).

The new <button> element is inserted in followlines.js script (thus only
visible if JavaScript is activated); it contains a "+" and "-" with a
"diff-semantics" style; upon hover, it scales up.

To find the parent element under which to insert the <button> we either rely
on the "data-selectabletag" attribute (which defines the HTML tag of children
of class="sourcelines" element e.g. <span> for filerevision view and <tr> for
annotate view) or use a child of the latter elements if we find an element
with class="followlines-btn-parent" (useful for annotate view, for which we
have to find the <td> in which to insert the <button>).

On noticeable change in CSS concerns the "margin-left" of span:before
pseudo-elements in filelog view that has been increased a bit in order to
leave space for the new button to appear between line number column and
line content one.
Also note the "z-index" addition for "annotate-info" box so that the latter
appears on top of new buttons (instead of getting hidden).

In some respect, the UI similar to line commenting feature that is implemented
in popular code hosting site like GitHub, BitBucket or Kallithea.

# commandserver.py - communicate with Mercurial's API over a pipe
#
#  Copyright 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 __future__ import absolute_import

import errno
import gc
import os
import random
import select
import signal
import socket
import struct
import traceback

from .i18n import _
from . import (
    encoding,
    error,
    pycompat,
    util,
)

logfile = None

def log(*args):
    if not logfile:
        return

    for a in args:
        logfile.write(str(a))

    logfile.flush()

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 '<%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('>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 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 '<%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 ''
        assert size > 0

        # tell the client we need at most size bytes
        self.out.write(struct.pack('>cI', channel, size))
        self.out.flush()

        length = self.in_.read(4)
        length = struct.unpack('>I', length)[0]
        if not length:
            return ''
        else:
            return self.in_.read(length)

    def readline(self, size=-1):
        if size < 0:
            size = self.maxchunksize
            s = self._read(size, 'L')
            buf = s
            # keep asking for more until there's either no more or
            # we got a full line
            while s and s[-1] != '\n':
                s = self._read(size, 'L')
                buf += s

            return buf
        else:
            return self._read(size, 'L')

    def __iter__(self):
        return self

    def next(self):
        l = self.readline()
        if not l:
            raise StopIteration
        return l

    def __getattr__(self, attr):
        if attr in ('isatty', 'fileno', 'tell', 'seek'):
            raise AttributeError(attr)
        return getattr(self.in_, attr)

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):
        self.cwd = pycompat.getcwd()

        # developer config: cmdserver.log
        logpath = ui.config("cmdserver", "log", None)
        if logpath:
            global logfile
            if logpath == '-':
                # write log on a special 'd' (debug) channel
                logfile = channeledoutput(fout, 'd')
            else:
                logfile = open(logpath, 'a')

        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.cerr = channeledoutput(fout, 'e')
        self.cout = channeledoutput(fout, 'o')
        self.cin = channeledinput(fin, fout, 'I')
        self.cresult = channeledoutput(fout, 'r')

        self.client = fin

    def cleanup(self):
        """release and restore resources taken during server session"""
        pass

    def _read(self, size):
        if not size:
            return ''

        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('>I', self._read(4))[0]
        if not length:
            return ''
        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('\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, 'fileno'):
                ui.setconfig('ui', 'nontty', 'true', 'commandserver')

        req = dispatch.request(args[:], copiedui, self.repo, self.cin,
                               self.cout, self.cerr)

        ret = (dispatch.dispatch(req) or 0) & 255 # might return None

        # restore old cwd
        if '--cwd' in args:
            os.chdir(self.cwd)

        self.cresult.write(struct.pack('>i', int(ret)))

    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(_('unknown command %s') % cmd)

        return cmd != ''

    capabilities = {'runcommand'  : runcommand,
                    'getencoding' : getencoding}

    def serve(self):
        hellomsg = 'capabilities: ' + ' '.join(sorted(self.capabilities))
        hellomsg += '\n'
        hellomsg += 'encoding: ' + encoding.encoding
        hellomsg += '\n'
        hellomsg += 'pid: %d' % util.getpid()
        if util.safehasattr(os, 'getpgid'):
            hellomsg += '\n'
            hellomsg += '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 _protectio(ui):
    """ duplicates streams and redirect original to null if ui uses stdio """
    ui.flush()
    newfiles = []
    nullfd = os.open(os.devnull, os.O_RDWR)
    for f, sysf, mode in [(ui.fin, util.stdin, pycompat.sysstr('rb')),
                          (ui.fout, util.stdout, pycompat.sysstr('wb'))]:
        if f is sysf:
            newfd = os.dup(f.fileno())
            os.dup2(nullfd, f.fileno())
            f = os.fdopen(newfd, mode)
        newfiles.append(f)
    os.close(nullfd)
    return tuple(newfiles)

def _restoreio(ui, fin, fout):
    """ restores streams from duplicated ones """
    ui.flush()
    for f, uif in [(fin, ui.fin), (fout, ui.fout)]:
        if f is not uif:
            os.dup2(f.fileno(), uif.fileno())
            f.close()

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.
        fin, fout = _protectio(ui)
        try:
            sv = server(ui, self.repo, fin, fout)
            return sv.serve()
        finally:
            sv.cleanup()
            _restoreio(ui, fin, fout)

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):
    fin = conn.makefile('rb')
    fout = conn.makefile('wb')
    sv = None
    try:
        sv = createcmdserver(repo, conn, fin, fout)
        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.warn(_('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, 'e')
        traceback.print_exc(file=cerr)
        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(_('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"""
        pass

    def createcmdserver(self, repo, conn, fin, fout):
        """Create new command server instance; called in the process that
        serves for the current connection"""
        return server(self.ui, repo, fin, fout)

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['address']
        if not util.safehasattr(socket, 'AF_UNIX'):
            raise error.Abort(_('unsupported platform'))
        if not self.address:
            raise error.Abort(_('no socket path specified with --address'))
        self._servicehandler = handler or unixservicehandler(ui)
        self._sock = None
        self._oldsigchldhandler = None
        self._workerpids = set()  # updated by signal handler; do not iterate
        self._socketunlinked = None

    def init(self):
        self._sock = socket.socket(socket.AF_UNIX)
        self._servicehandler.bindsocket(self._sock, self.address)
        o = signal.signal(signal.SIGCHLD, self._sigchldhandler)
        self._oldsigchldhandler = o
        self._socketunlinked = False

    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._unlinksocket()
        # 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
        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:
                ready = select.select([self._sock], [], [], h.pollinterval)[0]
                if not ready:
                    # only exit if we completed all queued requests
                    if exiting:
                        break
                    continue
                conn, _addr = self._sock.accept()
            except (select.error, socket.error) as inst:
                if inst.args[0] == errno.EINTR:
                    continue
                raise

            pid = os.fork()
            if pid:
                try:
                    self.ui.debug('forked worker process (pid=%d)\n' % pid)
                    self._workerpids.add(pid)
                    h.newconnection()
                finally:
                    conn.close()  # release handle in parent process
            else:
                try:
                    self._runworker(conn)
                    conn.close()
                    os._exit(0)
                except:  # never return, hence no re-raises
                    try:
                        self.ui.traceback(force=True)
                    finally:
                        os._exit(255)

    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.debug('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)
        finally:
            gc.collect()  # trigger __del__ since worker process uses os._exit