mercurial/templatekw.py

protocol: send application/mercurial-0.2 responses to capable clients

With this commit, the HTTP transport now parses the X-HgProto-<N>
header to determine what media type and compression engine to use for
responses. So far, we only compress responses that are already being
compressed with zlib today (stream response types to specific
commands). We can expand things to cover additional response types
later.

The practical side-effect of this commit is that non-zlib compression
engines will be used if both ends support them. This means if both
ends have zstd support, zstd - not zlib - will be used to compress
data!

When cloning the mozilla-unified repository between a local HTTP
server and client, the benefits of non-zlib compression are quite
noticeable:

  engine     server CPU (s)   client CPU (s)    bundle size
zlib (l=6)      174.1            283.2         1,148,547,026
zstd (l=1)       99.2            267.3         1,127,513,841
zstd (l=3)      103.1            266.9         1,018,861,363
zstd (l=7)      128.3            269.7           919,190,278
zstd (l=10)     162.0               -            894,547,179
none             95.3            277.2         4,097,566,064

The default zstd compression level is 3. So if you deploy zstd
capable Mercurial to your clients and servers and CPU time on
your server is dominated by "getbundle" requests (clients cloning
and pulling) - and my experience at Mozilla tells me this is often
the case - this commit could drastically reduce your server-side
CPU usage *and* save on bandwidth costs!

Another benefit of this change is that server operators can install
*any* compression engine. While it isn't enabled by default, the
"none" compression engine can now be used to disable wire protocol
compression completely. Previously, commands like "getbundle" always
zlib compressed output, adding considerable overhead to generating
responses. If you are on a high speed network and your server is under
high load, it might be advantageous to trade bandwidth for CPU.
Although, zstd at level 1 doesn't use that much CPU, so I'm not
convinced that disabling compression wholesale is worthwhile. And, my
data seems to indicate a slow down on the client without compression.
I suspect this is due to a lack of buffering resulting in an increase
in socket read() calls and/or the fact we're transferring an extra 3 GB
of data (parsing HTTP chunked transfer and processing extra TCP packets
can add up). This is definitely worth investigating and optimizing. But
since the "none" compressor isn't enabled by default, I'm inclined to
punt on this issue.

This commit introduces tons of tests. Some of these should arguably
have been implemented on previous commits. But it was difficult to
test without the server functionality in place.

# templatekw.py - common changeset template keywords
#
# Copyright 2005-2009 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

from .node import hex, nullid
from . import (
    encoding,
    error,
    hbisect,
    patch,
    registrar,
    scmutil,
    util,
)

# This helper class allows us to handle both:
#  "{files}" (legacy command-line-specific list hack) and
#  "{files % '{file}\n'}" (hgweb-style with inlining and function support)
# and to access raw values:
#  "{ifcontains(file, files, ...)}", "{ifcontains(key, extras, ...)}"
#  "{get(extras, key)}"

class _hybrid(object):
    def __init__(self, gen, values, makemap, joinfmt):
        self.gen = gen
        self.values = values
        self._makemap = makemap
        self.joinfmt = joinfmt
    def __iter__(self):
        return self.gen
    def itermaps(self):
        makemap = self._makemap
        for x in self.values:
            yield makemap(x)
    def __contains__(self, x):
        return x in self.values
    def __len__(self):
        return len(self.values)
    def __getattr__(self, name):
        if name != 'get':
            raise AttributeError(name)
        return getattr(self.values, name)

def showlist(name, values, plural=None, element=None, separator=' ', **args):
    if not element:
        element = name
    f = _showlist(name, values, plural, separator, **args)
    return _hybrid(f, values, lambda x: {element: x}, lambda d: d[element])

def _showlist(name, values, plural=None, separator=' ', **args):
    '''expand set of values.
    name is name of key in template map.
    values is list of strings or dicts.
    plural is plural of name, if not simply name + 's'.
    separator is used to join values as a string

    expansion works like this, given name 'foo'.

    if values is empty, expand 'no_foos'.

    if 'foo' not in template map, return values as a string,
    joined by 'separator'.

    expand 'start_foos'.

    for each value, expand 'foo'. if 'last_foo' in template
    map, expand it instead of 'foo' for last key.

    expand 'end_foos'.
    '''
    templ = args['templ']
    if plural:
        names = plural
    else: names = name + 's'
    if not values:
        noname = 'no_' + names
        if noname in templ:
            yield templ(noname, **args)
        return
    if name not in templ:
        if isinstance(values[0], str):
            yield separator.join(values)
        else:
            for v in values:
                yield dict(v, **args)
        return
    startname = 'start_' + names
    if startname in templ:
        yield templ(startname, **args)
    vargs = args.copy()
    def one(v, tag=name):
        try:
            vargs.update(v)
        except (AttributeError, ValueError):
            try:
                for a, b in v:
                    vargs[a] = b
            except ValueError:
                vargs[name] = v
        return templ(tag, **vargs)
    lastname = 'last_' + name
    if lastname in templ:
        last = values.pop()
    else:
        last = None
    for v in values:
        yield one(v)
    if last is not None:
        yield one(last, tag=lastname)
    endname = 'end_' + names
    if endname in templ:
        yield templ(endname, **args)

def _formatrevnode(ctx):
    """Format changeset as '{rev}:{node|formatnode}', which is the default
    template provided by cmdutil.changeset_templater"""
    repo = ctx.repo()
    if repo.ui.debugflag:
        hexnode = ctx.hex()
    else:
        hexnode = ctx.hex()[:12]
    return '%d:%s' % (scmutil.intrev(ctx.rev()), hexnode)

def getfiles(repo, ctx, revcache):
    if 'files' not in revcache:
        revcache['files'] = repo.status(ctx.p1(), ctx)[:3]
    return revcache['files']

def getlatesttags(repo, ctx, cache, pattern=None):
    '''return date, distance and name for the latest tag of rev'''

    cachename = 'latesttags'
    if pattern is not None:
        cachename += '-' + pattern
        match = util.stringmatcher(pattern)[2]
    else:
        match = util.always

    if cachename not in cache:
        # Cache mapping from rev to a tuple with tag date, tag
        # distance and tag name
        cache[cachename] = {-1: (0, 0, ['null'])}
    latesttags = cache[cachename]

    rev = ctx.rev()
    todo = [rev]
    while todo:
        rev = todo.pop()
        if rev in latesttags:
            continue
        ctx = repo[rev]
        tags = [t for t in ctx.tags()
                if (repo.tagtype(t) and repo.tagtype(t) != 'local'
                    and match(t))]
        if tags:
            latesttags[rev] = ctx.date()[0], 0, [t for t in sorted(tags)]
            continue
        try:
            # The tuples are laid out so the right one can be found by
            # comparison.
            pdate, pdist, ptag = max(
                latesttags[p.rev()] for p in ctx.parents())
        except KeyError:
            # Cache miss - recurse
            todo.append(rev)
            todo.extend(p.rev() for p in ctx.parents())
            continue
        latesttags[rev] = pdate, pdist + 1, ptag
    return latesttags[rev]

def getrenamedfn(repo, endrev=None):
    rcache = {}
    if endrev is None:
        endrev = len(repo)

    def getrenamed(fn, rev):
        '''looks up all renames for a file (up to endrev) the first
        time the file is given. It indexes on the changerev and only
        parses the manifest if linkrev != changerev.
        Returns rename info for fn at changerev rev.'''
        if fn not in rcache:
            rcache[fn] = {}
            fl = repo.file(fn)
            for i in fl:
                lr = fl.linkrev(i)
                renamed = fl.renamed(fl.node(i))
                rcache[fn][lr] = renamed
                if lr >= endrev:
                    break
        if rev in rcache[fn]:
            return rcache[fn][rev]

        # If linkrev != rev (i.e. rev not found in rcache) fallback to
        # filectx logic.
        try:
            return repo[rev][fn].renamed()
        except error.LookupError:
            return None

    return getrenamed

# keywords are callables like:
# fn(repo, ctx, templ, cache, revcache, **args)
# with:
# repo - current repository instance
# ctx - the changectx being displayed
# templ - the templater instance
# cache - a cache dictionary for the whole templater run
# revcache - a cache dictionary for the current revision
keywords = {}

templatekeyword = registrar.templatekeyword(keywords)

@templatekeyword('author')
def showauthor(repo, ctx, templ, **args):
    """String. The unmodified author of the changeset."""
    return ctx.user()

@templatekeyword('bisect')
def showbisect(repo, ctx, templ, **args):
    """String. The changeset bisection status."""
    return hbisect.label(repo, ctx.node())

@templatekeyword('branch')
def showbranch(**args):
    """String. The name of the branch on which the changeset was
    committed.
    """
    return args['ctx'].branch()

@templatekeyword('branches')
def showbranches(**args):
    """List of strings. The name of the branch on which the
    changeset was committed. Will be empty if the branch name was
    default. (DEPRECATED)
    """
    branch = args['ctx'].branch()
    if branch != 'default':
        return showlist('branch', [branch], plural='branches', **args)
    return showlist('branch', [], plural='branches', **args)

@templatekeyword('bookmarks')
def showbookmarks(**args):
    """List of strings. Any bookmarks associated with the
    changeset. Also sets 'active', the name of the active bookmark.
    """
    repo = args['ctx']._repo
    bookmarks = args['ctx'].bookmarks()
    active = repo._activebookmark
    makemap = lambda v: {'bookmark': v, 'active': active, 'current': active}
    f = _showlist('bookmark', bookmarks, **args)
    return _hybrid(f, bookmarks, makemap, lambda x: x['bookmark'])

@templatekeyword('children')
def showchildren(**args):
    """List of strings. The children of the changeset."""
    ctx = args['ctx']
    childrevs = ['%d:%s' % (cctx, cctx) for cctx in ctx.children()]
    return showlist('children', childrevs, element='child', **args)

# Deprecated, but kept alive for help generation a purpose.
@templatekeyword('currentbookmark')
def showcurrentbookmark(**args):
    """String. The active bookmark, if it is
    associated with the changeset (DEPRECATED)"""
    return showactivebookmark(**args)

@templatekeyword('activebookmark')
def showactivebookmark(**args):
    """String. The active bookmark, if it is
    associated with the changeset"""
    active = args['repo']._activebookmark
    if active and active in args['ctx'].bookmarks():
        return active
    return ''

@templatekeyword('date')
def showdate(repo, ctx, templ, **args):
    """Date information. The date when the changeset was committed."""
    return ctx.date()

@templatekeyword('desc')
def showdescription(repo, ctx, templ, **args):
    """String. The text of the changeset description."""
    s = ctx.description()
    if isinstance(s, encoding.localstr):
        # try hard to preserve utf-8 bytes
        return encoding.tolocal(encoding.fromlocal(s).strip())
    else:
        return s.strip()

@templatekeyword('diffstat')
def showdiffstat(repo, ctx, templ, **args):
    """String. Statistics of changes with the following format:
    "modified files: +added/-removed lines"
    """
    stats = patch.diffstatdata(util.iterlines(ctx.diff()))
    maxname, maxtotal, adds, removes, binary = patch.diffstatsum(stats)
    return '%s: +%s/-%s' % (len(stats), adds, removes)

@templatekeyword('extras')
def showextras(**args):
    """List of dicts with key, value entries of the 'extras'
    field of this changeset."""
    extras = args['ctx'].extra()
    extras = util.sortdict((k, extras[k]) for k in sorted(extras))
    makemap = lambda k: {'key': k, 'value': extras[k]}
    c = [makemap(k) for k in extras]
    f = _showlist('extra', c, plural='extras', **args)
    return _hybrid(f, extras, makemap,
                   lambda x: '%s=%s' % (x['key'], x['value']))

@templatekeyword('file_adds')
def showfileadds(**args):
    """List of strings. Files added by this changeset."""
    repo, ctx, revcache = args['repo'], args['ctx'], args['revcache']
    return showlist('file_add', getfiles(repo, ctx, revcache)[1],
                    element='file', **args)

@templatekeyword('file_copies')
def showfilecopies(**args):
    """List of strings. Files copied in this changeset with
    their sources.
    """
    cache, ctx = args['cache'], args['ctx']
    copies = args['revcache'].get('copies')
    if copies is None:
        if 'getrenamed' not in cache:
            cache['getrenamed'] = getrenamedfn(args['repo'])
        copies = []
        getrenamed = cache['getrenamed']
        for fn in ctx.files():
            rename = getrenamed(fn, ctx.rev())
            if rename:
                copies.append((fn, rename[0]))

    copies = util.sortdict(copies)
    makemap = lambda k: {'name': k, 'source': copies[k]}
    c = [makemap(k) for k in copies]
    f = _showlist('file_copy', c, plural='file_copies', **args)
    return _hybrid(f, copies, makemap,
                   lambda x: '%s (%s)' % (x['name'], x['source']))

# showfilecopiesswitch() displays file copies only if copy records are
# provided before calling the templater, usually with a --copies
# command line switch.
@templatekeyword('file_copies_switch')
def showfilecopiesswitch(**args):
    """List of strings. Like "file_copies" but displayed
    only if the --copied switch is set.
    """
    copies = args['revcache'].get('copies') or []
    copies = util.sortdict(copies)
    makemap = lambda k: {'name': k, 'source': copies[k]}
    c = [makemap(k) for k in copies]
    f = _showlist('file_copy', c, plural='file_copies', **args)
    return _hybrid(f, copies, makemap,
                   lambda x: '%s (%s)' % (x['name'], x['source']))

@templatekeyword('file_dels')
def showfiledels(**args):
    """List of strings. Files removed by this changeset."""
    repo, ctx, revcache = args['repo'], args['ctx'], args['revcache']
    return showlist('file_del', getfiles(repo, ctx, revcache)[2],
                    element='file', **args)

@templatekeyword('file_mods')
def showfilemods(**args):
    """List of strings. Files modified by this changeset."""
    repo, ctx, revcache = args['repo'], args['ctx'], args['revcache']
    return showlist('file_mod', getfiles(repo, ctx, revcache)[0],
                    element='file', **args)

@templatekeyword('files')
def showfiles(**args):
    """List of strings. All files modified, added, or removed by this
    changeset.
    """
    return showlist('file', args['ctx'].files(), **args)

@templatekeyword('graphnode')
def showgraphnode(repo, ctx, **args):
    """String. The character representing the changeset node in
    an ASCII revision graph"""
    wpnodes = repo.dirstate.parents()
    if wpnodes[1] == nullid:
        wpnodes = wpnodes[:1]
    if ctx.node() in wpnodes:
        return '@'
    elif ctx.obsolete():
        return 'x'
    elif ctx.closesbranch():
        return '_'
    else:
        return 'o'

@templatekeyword('latesttag')
def showlatesttag(**args):
    """List of strings. The global tags on the most recent globally
    tagged ancestor of this changeset.
    """
    return showlatesttags(None, **args)

def showlatesttags(pattern, **args):
    """helper method for the latesttag keyword and function"""
    repo, ctx = args['repo'], args['ctx']
    cache = args['cache']
    latesttags = getlatesttags(repo, ctx, cache, pattern)

    # latesttag[0] is an implementation detail for sorting csets on different
    # branches in a stable manner- it is the date the tagged cset was created,
    # not the date the tag was created.  Therefore it isn't made visible here.
    makemap = lambda v: {
        'changes': _showchangessincetag,
        'distance': latesttags[1],
        'latesttag': v,   # BC with {latesttag % '{latesttag}'}
        'tag': v
    }

    tags = latesttags[2]
    f = _showlist('latesttag', tags, separator=':', **args)
    return _hybrid(f, tags, makemap, lambda x: x['latesttag'])

@templatekeyword('latesttagdistance')
def showlatesttagdistance(repo, ctx, templ, cache, **args):
    """Integer. Longest path to the latest tag."""
    return getlatesttags(repo, ctx, cache)[1]

@templatekeyword('changessincelatesttag')
def showchangessincelatesttag(repo, ctx, templ, cache, **args):
    """Integer. All ancestors not in the latest tag."""
    latesttag = getlatesttags(repo, ctx, cache)[2][0]

    return _showchangessincetag(repo, ctx, tag=latesttag, **args)

def _showchangessincetag(repo, ctx, **args):
    offset = 0
    revs = [ctx.rev()]
    tag = args['tag']

    # The only() revset doesn't currently support wdir()
    if ctx.rev() is None:
        offset = 1
        revs = [p.rev() for p in ctx.parents()]

    return len(repo.revs('only(%ld, %s)', revs, tag)) + offset

@templatekeyword('manifest')
def showmanifest(**args):
    repo, ctx, templ = args['repo'], args['ctx'], args['templ']
    mnode = ctx.manifestnode()
    if mnode is None:
        # just avoid crash, we might want to use the 'ff...' hash in future
        return
    args = args.copy()
    args.update({'rev': repo.manifestlog._revlog.rev(mnode),
                 'node': hex(mnode)})
    return templ('manifest', **args)

def shownames(namespace, **args):
    """helper method to generate a template keyword for a namespace"""
    ctx = args['ctx']
    repo = ctx.repo()
    ns = repo.names[namespace]
    names = ns.names(repo, ctx.node())
    return showlist(ns.templatename, names, plural=namespace, **args)

@templatekeyword('namespaces')
def shownamespaces(**args):
    """Dict of lists. Names attached to this changeset per
    namespace."""
    ctx = args['ctx']
    repo = ctx.repo()
    namespaces = util.sortdict((k, showlist('name', ns.names(repo, ctx.node()),
                                            **args))
                               for k, ns in repo.names.iteritems())
    f = _showlist('namespace', list(namespaces), **args)
    return _hybrid(f, namespaces,
                   lambda k: {'namespace': k, 'names': namespaces[k]},
                   lambda x: x['namespace'])

@templatekeyword('node')
def shownode(repo, ctx, templ, **args):
    """String. The changeset identification hash, as a 40 hexadecimal
    digit string.
    """
    return ctx.hex()

@templatekeyword('p1rev')
def showp1rev(repo, ctx, templ, **args):
    """Integer. The repository-local revision number of the changeset's
    first parent, or -1 if the changeset has no parents."""
    return ctx.p1().rev()

@templatekeyword('p2rev')
def showp2rev(repo, ctx, templ, **args):
    """Integer. The repository-local revision number of the changeset's
    second parent, or -1 if the changeset has no second parent."""
    return ctx.p2().rev()

@templatekeyword('p1node')
def showp1node(repo, ctx, templ, **args):
    """String. The identification hash of the changeset's first parent,
    as a 40 digit hexadecimal string. If the changeset has no parents, all
    digits are 0."""
    return ctx.p1().hex()

@templatekeyword('p2node')
def showp2node(repo, ctx, templ, **args):
    """String. The identification hash of the changeset's second
    parent, as a 40 digit hexadecimal string. If the changeset has no second
    parent, all digits are 0."""
    return ctx.p2().hex()

@templatekeyword('parents')
def showparents(**args):
    """List of strings. The parents of the changeset in "rev:node"
    format. If the changeset has only one "natural" parent (the predecessor
    revision) nothing is shown."""
    repo = args['repo']
    ctx = args['ctx']
    pctxs = scmutil.meaningfulparents(repo, ctx)
    prevs = [str(p.rev()) for p in pctxs]  # ifcontains() needs a list of str
    parents = [[('rev', p.rev()),
                ('node', p.hex()),
                ('phase', p.phasestr())]
               for p in pctxs]
    f = _showlist('parent', parents, **args)
    return _hybrid(f, prevs, lambda x: {'ctx': repo[int(x)], 'revcache': {}},
                   lambda d: _formatrevnode(d['ctx']))

@templatekeyword('phase')
def showphase(repo, ctx, templ, **args):
    """String. The changeset phase name."""
    return ctx.phasestr()

@templatekeyword('phaseidx')
def showphaseidx(repo, ctx, templ, **args):
    """Integer. The changeset phase index."""
    return ctx.phase()

@templatekeyword('rev')
def showrev(repo, ctx, templ, **args):
    """Integer. The repository-local changeset revision number."""
    return scmutil.intrev(ctx.rev())

def showrevslist(name, revs, **args):
    """helper to generate a list of revisions in which a mapped template will
    be evaluated"""
    repo = args['ctx'].repo()
    revs = [str(r) for r in revs]  # ifcontains() needs a list of str
    f = _showlist(name, revs, **args)
    return _hybrid(f, revs,
                   lambda x: {name: x, 'ctx': repo[int(x)], 'revcache': {}},
                   lambda d: d[name])

@templatekeyword('subrepos')
def showsubrepos(**args):
    """List of strings. Updated subrepositories in the changeset."""
    ctx = args['ctx']
    substate = ctx.substate
    if not substate:
        return showlist('subrepo', [], **args)
    psubstate = ctx.parents()[0].substate or {}
    subrepos = []
    for sub in substate:
        if sub not in psubstate or substate[sub] != psubstate[sub]:
            subrepos.append(sub) # modified or newly added in ctx
    for sub in psubstate:
        if sub not in substate:
            subrepos.append(sub) # removed in ctx
    return showlist('subrepo', sorted(subrepos), **args)

# don't remove "showtags" definition, even though namespaces will put
# a helper function for "tags" keyword into "keywords" map automatically,
# because online help text is built without namespaces initialization
@templatekeyword('tags')
def showtags(**args):
    """List of strings. Any tags associated with the changeset."""
    return shownames('tags', **args)

def loadkeyword(ui, extname, registrarobj):
    """Load template keyword from specified registrarobj
    """
    for name, func in registrarobj._table.iteritems():
        keywords[name] = func

@templatekeyword('termwidth')
def termwidth(repo, ctx, templ, **args):
    """Integer. The width of the current terminal."""
    return repo.ui.termwidth()

@templatekeyword('troubles')
def showtroubles(**args):
    """List of strings. Evolution troubles affecting the changeset.

    (EXPERIMENTAL)
    """
    return showlist('trouble', args['ctx'].troubles(), **args)

# tell hggettext to extract docstrings from these functions:
i18nfunctions = keywords.values()