view mercurial/color.py @ 40022:33eb670e2834

wireprotov2: define semantics for content redirects

When I implemented the clonebundles feature and deployed it on
hg.mozilla.org using Amazon S3 as a content server, server-side CPU
and bandwidth usage dropped off a cliff and a ton of server scaling
headaches went away pretty much the instant clients with support for
clonebundles were rolled out to Firefox CI.

An obvious takeaway from that experience was that offloading server
load to scalable file servers - potentially backed by a CDN - is a
really good idea. Another takeaway was that Mercurial's wire protocol
wasn't in a good position to support data offload generally.

In wire protocol version 1, there isn't a mechanism in the protocol to
say "grab the data from over here instead." For HTTP, we could teach
the client to follow HTTP redirects. Or we could invent a media type
that encoded redirects inline. But for SSH, we were pretty much out of
luck because that protocol wasn't very flexible.

Wire protocol version 2 offers the opportunity to do something better.

The recent generic server-side content caching layer in the wire
protocol version 2 server demonstrated that it is possible to have
drop-in caching of responses to command requests. This by itself
adds tons of value and already makes the built-in server much more
scalable. But I don't want to stop there.

The existing server-side caching implementation has a big weakness:
it requires the server to send data to the client. This means that
the Mercurial server is potentially sending gigabytes of data to
thousands of clients. This is problematic because compared to scaling
static file servers, scaling dynamic servers is *hard*.

A solution to this is to "offload" serving of content to something
that isn't the Mercurial server. By offloading content serving, you
turn the Mercurial server from a centralized monolithic service to
a distributed mostly-indexing service. Assuming high rates of content
offload, this should drastically reduce the total work performed by
the Mercurial server, both in terms of CPU and data transfer. This
will make Mercurial servers vastly easier to scale.

This commit defines the semantics for "content redirects" in wire
protocol version 2. Essentially:

* Servers advertise the set of locations a response could be served
  from.
* When making requests, clients advertise the set of locations they
  are willing to fetch content from.
* Servers can then replace the inline response with one that says
  "get the response from over here instead."

This feature - when fully implemented - will allow extending the
server-side caching layer to facilitate such things as integrating
your server-side cache with a scalable blob store (such as S3 or
a CDN) and offloading most data transfer to that external service.

This feature could also be leveraged for load balancing. e.g.
requests could come into a central server and then get redirected
to an available mirror depending on server availability or locality.
There's tons of potential :)

Differential Revision: https://phab.mercurial-scm.org/D4774

# utility for color output for Mercurial commands
#
# Copyright (C) 2007 Kevin Christen <[e-mail]> and other
#
# 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 re

from .i18n import _

from . import (
    encoding,
    pycompat,
)

from .utils import (
    stringutil,
)

try:
    import curses
    # Mapping from effect name to terminfo attribute name (or raw code) or
    # color number.  This will also force-load the curses module.
    _baseterminfoparams = {
        'none': (True, 'sgr0', ''),
        'standout': (True, 'smso', ''),
        'underline': (True, 'smul', ''),
        'reverse': (True, 'rev', ''),
        'inverse': (True, 'rev', ''),
        'blink': (True, 'blink', ''),
        'dim': (True, 'dim', ''),
        'bold': (True, 'bold', ''),
        'invisible': (True, 'invis', ''),
        'italic': (True, 'sitm', ''),
        'black': (False, curses.COLOR_BLACK, ''),
        'red': (False, curses.COLOR_RED, ''),
        'green': (False, curses.COLOR_GREEN, ''),
        'yellow': (False, curses.COLOR_YELLOW, ''),
        'blue': (False, curses.COLOR_BLUE, ''),
        'magenta': (False, curses.COLOR_MAGENTA, ''),
        'cyan': (False, curses.COLOR_CYAN, ''),
        'white': (False, curses.COLOR_WHITE, ''),
    }
except ImportError:
    curses = None
    _baseterminfoparams = {}

# start and stop parameters for effects
_effects = {
    'none': 0,
    'black': 30,
    'red': 31,
    'green': 32,
    'yellow': 33,
    'blue': 34,
    'magenta': 35,
    'cyan': 36,
    'white': 37,
    'bold': 1,
    'italic': 3,
    'underline': 4,
    'inverse': 7,
    'dim': 2,
    'black_background': 40,
    'red_background': 41,
    'green_background': 42,
    'yellow_background': 43,
    'blue_background': 44,
    'purple_background': 45,
    'cyan_background': 46,
    'white_background': 47,
    }

_defaultstyles = {
    'grep.match': 'red bold',
    'grep.linenumber': 'green',
    'grep.rev': 'green',
    'grep.change': 'green',
    'grep.sep': 'cyan',
    'grep.filename': 'magenta',
    'grep.user': 'magenta',
    'grep.date': 'magenta',
    'addremove.added': 'green',
    'addremove.removed': 'red',
    'bookmarks.active': 'green',
    'branches.active': 'none',
    'branches.closed': 'black bold',
    'branches.current': 'green',
    'branches.inactive': 'none',
    'diff.changed': 'white',
    'diff.deleted': 'red',
    'diff.deleted.changed': 'red bold underline',
    'diff.deleted.unchanged': 'red',
    'diff.diffline': 'bold',
    'diff.extended': 'cyan bold',
    'diff.file_a': 'red bold',
    'diff.file_b': 'green bold',
    'diff.hunk': 'magenta',
    'diff.inserted': 'green',
    'diff.inserted.changed': 'green bold underline',
    'diff.inserted.unchanged': 'green',
    'diff.tab': '',
    'diff.trailingwhitespace': 'bold red_background',
    'changeset.public': '',
    'changeset.draft': '',
    'changeset.secret': '',
    'diffstat.deleted': 'red',
    'diffstat.inserted': 'green',
    'formatvariant.name.mismatchconfig': 'red',
    'formatvariant.name.mismatchdefault': 'yellow',
    'formatvariant.name.uptodate': 'green',
    'formatvariant.repo.mismatchconfig': 'red',
    'formatvariant.repo.mismatchdefault': 'yellow',
    'formatvariant.repo.uptodate': 'green',
    'formatvariant.config.special': 'yellow',
    'formatvariant.config.default': 'green',
    'formatvariant.default': '',
    'histedit.remaining': 'red bold',
    'ui.error': 'red',
    'ui.prompt': 'yellow',
    'log.changeset': 'yellow',
    'patchbomb.finalsummary': '',
    'patchbomb.from': 'magenta',
    'patchbomb.to': 'cyan',
    'patchbomb.subject': 'green',
    'patchbomb.diffstats': '',
    'rebase.rebased': 'blue',
    'rebase.remaining': 'red bold',
    'resolve.resolved': 'green bold',
    'resolve.unresolved': 'red bold',
    'shelve.age': 'cyan',
    'shelve.newest': 'green bold',
    'shelve.name': 'blue bold',
    'status.added': 'green bold',
    'status.clean': 'none',
    'status.copied': 'none',
    'status.deleted': 'cyan bold underline',
    'status.ignored': 'black bold',
    'status.modified': 'blue bold',
    'status.removed': 'red bold',
    'status.unknown': 'magenta bold underline',
    'tags.normal': 'green',
    'tags.local': 'black bold',
}

def loadcolortable(ui, extname, colortable):
    _defaultstyles.update(colortable)

def _terminfosetup(ui, mode, formatted):
    '''Initialize terminfo data and the terminal if we're in terminfo mode.'''

    # If we failed to load curses, we go ahead and return.
    if curses is None:
        return
    # Otherwise, see what the config file says.
    if mode not in ('auto', 'terminfo'):
        return
    ui._terminfoparams.update(_baseterminfoparams)

    for key, val in ui.configitems('color'):
        if key.startswith('color.'):
            newval = (False, int(val), '')
            ui._terminfoparams[key[6:]] = newval
        elif key.startswith('terminfo.'):
            newval = (True, '', val.replace('\\E', '\x1b'))
            ui._terminfoparams[key[9:]] = newval
    try:
        curses.setupterm()
    except curses.error as e:
        ui._terminfoparams.clear()
        return

    for key, (b, e, c) in ui._terminfoparams.copy().items():
        if not b:
            continue
        if not c and not curses.tigetstr(pycompat.sysstr(e)):
            # Most terminals don't support dim, invis, etc, so don't be
            # noisy and use ui.debug().
            ui.debug("no terminfo entry for %s\n" % e)
            del ui._terminfoparams[key]
    if not curses.tigetstr(r'setaf') or not curses.tigetstr(r'setab'):
        # Only warn about missing terminfo entries if we explicitly asked for
        # terminfo mode and we're in a formatted terminal.
        if mode == "terminfo" and formatted:
            ui.warn(_("no terminfo entry for setab/setaf: reverting to "
              "ECMA-48 color\n"))
        ui._terminfoparams.clear()

def setup(ui):
    """configure color on a ui

    That function both set the colormode for the ui object and read
    the configuration looking for custom colors and effect definitions."""
    mode = _modesetup(ui)
    ui._colormode = mode
    if mode and mode != 'debug':
        configstyles(ui)

def _modesetup(ui):
    if ui.plain('color'):
        return None
    config = ui.config('ui', 'color')
    if config == 'debug':
        return 'debug'

    auto = (config == 'auto')
    always = False
    if not auto and stringutil.parsebool(config):
        # We want the config to behave like a boolean, "on" is actually auto,
        # but "always" value is treated as a special case to reduce confusion.
        if ui.configsource('ui', 'color') == '--color' or config == 'always':
            always = True
        else:
            auto = True

    if not always and not auto:
        return None

    formatted = (always or (encoding.environ.get('TERM') != 'dumb'
                 and ui.formatted()))

    mode = ui.config('color', 'mode')

    # If pager is active, color.pagermode overrides color.mode.
    if getattr(ui, 'pageractive', False):
        mode = ui.config('color', 'pagermode', mode)

    realmode = mode
    if pycompat.iswindows:
        from . import win32

        term = encoding.environ.get('TERM')
        # TERM won't be defined in a vanilla cmd.exe environment.

        # UNIX-like environments on Windows such as Cygwin and MSYS will
        # set TERM. They appear to make a best effort attempt at setting it
        # to something appropriate. However, not all environments with TERM
        # defined support ANSI.
        ansienviron = term and 'xterm' in term

        if mode == 'auto':
            # Since "ansi" could result in terminal gibberish, we error on the
            # side of selecting "win32". However, if w32effects is not defined,
            # we almost certainly don't support "win32", so don't even try.
            # w32ffects is not populated when stdout is redirected, so checking
            # it first avoids win32 calls in a state known to error out.
            if ansienviron or not w32effects or win32.enablevtmode():
                realmode = 'ansi'
            else:
                realmode = 'win32'
        # An empty w32effects is a clue that stdout is redirected, and thus
        # cannot enable VT mode.
        elif mode == 'ansi' and w32effects and not ansienviron:
            win32.enablevtmode()
    elif mode == 'auto':
        realmode = 'ansi'

    def modewarn():
        # only warn if color.mode was explicitly set and we're in
        # a formatted terminal
        if mode == realmode and formatted:
            ui.warn(_('warning: failed to set color mode to %s\n') % mode)

    if realmode == 'win32':
        ui._terminfoparams.clear()
        if not w32effects:
            modewarn()
            return None
    elif realmode == 'ansi':
        ui._terminfoparams.clear()
    elif realmode == 'terminfo':
        _terminfosetup(ui, mode, formatted)
        if not ui._terminfoparams:
            ## FIXME Shouldn't we return None in this case too?
            modewarn()
            realmode = 'ansi'
    else:
        return None

    if always or (auto and formatted):
        return realmode
    return None

def configstyles(ui):
    ui._styles.update(_defaultstyles)
    for status, cfgeffects in ui.configitems('color'):
        if '.' not in status or status.startswith(('color.', 'terminfo.')):
            continue
        cfgeffects = ui.configlist('color', status)
        if cfgeffects:
            good = []
            for e in cfgeffects:
                if valideffect(ui, e):
                    good.append(e)
                else:
                    ui.warn(_("ignoring unknown color/effect %r "
                              "(configured in color.%s)\n")
                            % (e, status))
            ui._styles[status] = ' '.join(good)

def _activeeffects(ui):
    '''Return the effects map for the color mode set on the ui.'''
    if ui._colormode == 'win32':
        return w32effects
    elif ui._colormode is not None:
        return _effects
    return {}

def valideffect(ui, effect):
    'Determine if the effect is valid or not.'
    return ((not ui._terminfoparams and effect in _activeeffects(ui))
             or (effect in ui._terminfoparams
                 or effect[:-11] in ui._terminfoparams))

def _effect_str(ui, effect):
    '''Helper function for render_effects().'''

    bg = False
    if effect.endswith('_background'):
        bg = True
        effect = effect[:-11]
    try:
        attr, val, termcode = ui._terminfoparams[effect]
    except KeyError:
        return ''
    if attr:
        if termcode:
            return termcode
        else:
            return curses.tigetstr(pycompat.sysstr(val))
    elif bg:
        return curses.tparm(curses.tigetstr(r'setab'), val)
    else:
        return curses.tparm(curses.tigetstr(r'setaf'), val)

def _mergeeffects(text, start, stop):
    """Insert start sequence at every occurrence of stop sequence

    >>> s = _mergeeffects(b'cyan', b'[C]', b'|')
    >>> s = _mergeeffects(s + b'yellow', b'[Y]', b'|')
    >>> s = _mergeeffects(b'ma' + s + b'genta', b'[M]', b'|')
    >>> s = _mergeeffects(b'red' + s, b'[R]', b'|')
    >>> s
    '[R]red[M]ma[Y][C]cyan|[R][M][Y]yellow|[R][M]genta|'
    """
    parts = []
    for t in text.split(stop):
        if not t:
            continue
        parts.extend([start, t, stop])
    return ''.join(parts)

def _render_effects(ui, text, effects):
    'Wrap text in commands to turn on each effect.'
    if not text:
        return text
    if ui._terminfoparams:
        start = ''.join(_effect_str(ui, effect)
                        for effect in ['none'] + effects.split())
        stop = _effect_str(ui, 'none')
    else:
        activeeffects = _activeeffects(ui)
        start = [pycompat.bytestr(activeeffects[e])
                 for e in ['none'] + effects.split()]
        start = '\033[' + ';'.join(start) + 'm'
        stop = '\033[' + pycompat.bytestr(activeeffects['none']) + 'm'
    return _mergeeffects(text, start, stop)

_ansieffectre = re.compile(br'\x1b\[[0-9;]*m')

def stripeffects(text):
    """Strip ANSI control codes which could be inserted by colorlabel()"""
    return _ansieffectre.sub('', text)

def colorlabel(ui, msg, label):
    """add color control code according to the mode"""
    if ui._colormode == 'debug':
        if label and msg:
            if msg.endswith('\n'):
                msg = "[%s|%s]\n" % (label, msg[:-1])
            else:
                msg = "[%s|%s]" % (label, msg)
    elif ui._colormode is not None:
        effects = []
        for l in label.split():
            s = ui._styles.get(l, '')
            if s:
                effects.append(s)
            elif valideffect(ui, l):
                effects.append(l)
        effects = ' '.join(effects)
        if effects:
            msg = '\n'.join([_render_effects(ui, line, effects)
                             for line in msg.split('\n')])
    return msg

w32effects = None
if pycompat.iswindows:
    import ctypes

    _kernel32 = ctypes.windll.kernel32

    _WORD = ctypes.c_ushort

    _INVALID_HANDLE_VALUE = -1

    class _COORD(ctypes.Structure):
        _fields_ = [(r'X', ctypes.c_short),
                    (r'Y', ctypes.c_short)]

    class _SMALL_RECT(ctypes.Structure):
        _fields_ = [(r'Left', ctypes.c_short),
                    (r'Top', ctypes.c_short),
                    (r'Right', ctypes.c_short),
                    (r'Bottom', ctypes.c_short)]

    class _CONSOLE_SCREEN_BUFFER_INFO(ctypes.Structure):
        _fields_ = [(r'dwSize', _COORD),
                    (r'dwCursorPosition', _COORD),
                    (r'wAttributes', _WORD),
                    (r'srWindow', _SMALL_RECT),
                    (r'dwMaximumWindowSize', _COORD)]

    _STD_OUTPUT_HANDLE = 0xfffffff5 # (DWORD)-11
    _STD_ERROR_HANDLE = 0xfffffff4  # (DWORD)-12

    _FOREGROUND_BLUE = 0x0001
    _FOREGROUND_GREEN = 0x0002
    _FOREGROUND_RED = 0x0004
    _FOREGROUND_INTENSITY = 0x0008

    _BACKGROUND_BLUE = 0x0010
    _BACKGROUND_GREEN = 0x0020
    _BACKGROUND_RED = 0x0040
    _BACKGROUND_INTENSITY = 0x0080

    _COMMON_LVB_REVERSE_VIDEO = 0x4000
    _COMMON_LVB_UNDERSCORE = 0x8000

    # http://msdn.microsoft.com/en-us/library/ms682088%28VS.85%29.aspx
    w32effects = {
        'none': -1,
        'black': 0,
        'red': _FOREGROUND_RED,
        'green': _FOREGROUND_GREEN,
        'yellow': _FOREGROUND_RED | _FOREGROUND_GREEN,
        'blue': _FOREGROUND_BLUE,
        'magenta': _FOREGROUND_BLUE | _FOREGROUND_RED,
        'cyan': _FOREGROUND_BLUE | _FOREGROUND_GREEN,
        'white': _FOREGROUND_RED | _FOREGROUND_GREEN | _FOREGROUND_BLUE,
        'bold': _FOREGROUND_INTENSITY,
        'black_background': 0x100,                  # unused value > 0x0f
        'red_background': _BACKGROUND_RED,
        'green_background': _BACKGROUND_GREEN,
        'yellow_background': _BACKGROUND_RED | _BACKGROUND_GREEN,
        'blue_background': _BACKGROUND_BLUE,
        'purple_background': _BACKGROUND_BLUE | _BACKGROUND_RED,
        'cyan_background': _BACKGROUND_BLUE | _BACKGROUND_GREEN,
        'white_background': (_BACKGROUND_RED | _BACKGROUND_GREEN |
                             _BACKGROUND_BLUE),
        'bold_background': _BACKGROUND_INTENSITY,
        'underline': _COMMON_LVB_UNDERSCORE,  # double-byte charsets only
        'inverse': _COMMON_LVB_REVERSE_VIDEO, # double-byte charsets only
    }

    passthrough = {_FOREGROUND_INTENSITY,
                   _BACKGROUND_INTENSITY,
                   _COMMON_LVB_UNDERSCORE,
                   _COMMON_LVB_REVERSE_VIDEO}

    stdout = _kernel32.GetStdHandle(
                  _STD_OUTPUT_HANDLE)  # don't close the handle returned
    if stdout is None or stdout == _INVALID_HANDLE_VALUE:
        w32effects = None
    else:
        csbi = _CONSOLE_SCREEN_BUFFER_INFO()
        if not _kernel32.GetConsoleScreenBufferInfo(
                    stdout, ctypes.byref(csbi)):
            # stdout may not support GetConsoleScreenBufferInfo()
            # when called from subprocess or redirected
            w32effects = None
        else:
            origattr = csbi.wAttributes
            ansire = re.compile(b'\033\[([^m]*)m([^\033]*)(.*)',
                                re.MULTILINE | re.DOTALL)

    def win32print(ui, writefunc, *msgs, **opts):
        for text in msgs:
            _win32print(ui, text, writefunc, **opts)

    def _win32print(ui, text, writefunc, **opts):
        label = opts.get(r'label', '')
        attr = origattr

        def mapcolor(val, attr):
            if val == -1:
                return origattr
            elif val in passthrough:
                return attr | val
            elif val > 0x0f:
                return (val & 0x70) | (attr & 0x8f)
            else:
                return (val & 0x07) | (attr & 0xf8)

        # determine console attributes based on labels
        for l in label.split():
            style = ui._styles.get(l, '')
            for effect in style.split():
                try:
                    attr = mapcolor(w32effects[effect], attr)
                except KeyError:
                    # w32effects could not have certain attributes so we skip
                    # them if not found
                    pass
        # hack to ensure regexp finds data
        if not text.startswith(b'\033['):
            text = b'\033[m' + text

        # Look for ANSI-like codes embedded in text
        m = re.match(ansire, text)

        try:
            while m:
                for sattr in m.group(1).split(b';'):
                    if sattr:
                        attr = mapcolor(int(sattr), attr)
                ui.flush()
                _kernel32.SetConsoleTextAttribute(stdout, attr)
                writefunc(m.group(2), **opts)
                m = re.match(ansire, m.group(3))
        finally:
            # Explicitly reset original attributes
            ui.flush()
            _kernel32.SetConsoleTextAttribute(stdout, origattr)