mercurial/templatefilters.py

sparse-read: move from a recursive-based approach to a heap-based one

The previous recursive approach was trying to optimise each read slice to have
a good density. It had the tendency to over-optimize smaller slices while
leaving larger hole in others.

The new approach focuses on improving the combined density of all the reads,
instead of the individual slices. It slices at the largest gaps first, as they
reduce the total amount of read data the most efficiently.

Another benefit of this approach is that we iterate over the delta chain only
once, reducing the overhead of slicing long delta chains.

On the repository we use for tests, the new approach shows similar or faster
performance than the current default linear full read.

The repository contains about 450,000 revisions with many concurrent
topological branches. Tests have been run on two versions of the repository:
one built with the current delta constraint, and the other with an unlimited
delta span (using 'experimental.maxdeltachainspan=0')

Below are timings for building 1% of all the revision in the manifest log using
'hg perfrevlogrevisions -m'. Times are given in seconds. They include the new
couple of follow-up changeset in this series.

delta-span  standard    unlimited
linear-read     922s         632s
sparse-read     814s         566s

# templatefilters.py - common template expansion filters
#
# Copyright 2005-2008 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 os
import re
import time

from . import (
    encoding,
    error,
    hbisect,
    node,
    pycompat,
    registrar,
    templatekw,
    url,
    util,
)

urlerr = util.urlerr
urlreq = util.urlreq

if pycompat.ispy3:
    long = int

# filters are callables like:
#   fn(obj)
# with:
#   obj - object to be filtered (text, date, list and so on)
filters = {}

templatefilter = registrar.templatefilter(filters)

@templatefilter('addbreaks')
def addbreaks(text):
    """Any text. Add an XHTML "<br />" tag before the end of
    every line except the last.
    """
    return text.replace('\n', '<br/>\n')

agescales = [("year", 3600 * 24 * 365, 'Y'),
             ("month", 3600 * 24 * 30, 'M'),
             ("week", 3600 * 24 * 7, 'W'),
             ("day", 3600 * 24, 'd'),
             ("hour", 3600, 'h'),
             ("minute", 60, 'm'),
             ("second", 1, 's')]

@templatefilter('age')
def age(date, abbrev=False):
    """Date. Returns a human-readable date/time difference between the
    given date/time and the current date/time.
    """

    def plural(t, c):
        if c == 1:
            return t
        return t + "s"
    def fmt(t, c, a):
        if abbrev:
            return "%d%s" % (c, a)
        return "%d %s" % (c, plural(t, c))

    now = time.time()
    then = date[0]
    future = False
    if then > now:
        future = True
        delta = max(1, int(then - now))
        if delta > agescales[0][1] * 30:
            return 'in the distant future'
    else:
        delta = max(1, int(now - then))
        if delta > agescales[0][1] * 2:
            return util.shortdate(date)

    for t, s, a in agescales:
        n = delta // s
        if n >= 2 or s == 1:
            if future:
                return '%s from now' % fmt(t, n, a)
            return '%s ago' % fmt(t, n, a)

@templatefilter('basename')
def basename(path):
    """Any text. Treats the text as a path, and returns the last
    component of the path after splitting by the path separator
    (ignoring trailing separators). For example, "foo/bar/baz" becomes
    "baz" and "foo/bar//" becomes "bar".
    """
    return os.path.basename(path)

@templatefilter('count')
def count(i):
    """List or text. Returns the length as an integer."""
    return len(i)

@templatefilter('domain')
def domain(author):
    """Any text. Finds the first string that looks like an email
    address, and extracts just the domain component. Example: ``User
    <[e-mail]>`` becomes ``example.com``.
    """
    f = author.find('@')
    if f == -1:
        return ''
    author = author[f + 1:]
    f = author.find('>')
    if f >= 0:
        author = author[:f]
    return author

@templatefilter('email')
def email(text):
    """Any text. Extracts the first string that looks like an email
    address. Example: ``User <[e-mail]>`` becomes
    ``[e-mail]``.
    """
    return util.email(text)

@templatefilter('escape')
def escape(text):
    """Any text. Replaces the special XML/XHTML characters "&", "<"
    and ">" with XML entities, and filters out NUL characters.
    """
    return url.escape(text.replace('\0', ''), True)

para_re = None
space_re = None

def fill(text, width, initindent='', hangindent=''):
    '''fill many paragraphs with optional indentation.'''
    global para_re, space_re
    if para_re is None:
        para_re = re.compile('(\n\n|\n\\s*[-*]\\s*)', re.M)
        space_re = re.compile(r'  +')

    def findparas():
        start = 0
        while True:
            m = para_re.search(text, start)
            if not m:
                uctext = unicode(text[start:], encoding.encoding)
                w = len(uctext)
                while 0 < w and uctext[w - 1].isspace():
                    w -= 1
                yield (uctext[:w].encode(encoding.encoding),
                       uctext[w:].encode(encoding.encoding))
                break
            yield text[start:m.start(0)], m.group(1)
            start = m.end(1)

    return "".join([util.wrap(space_re.sub(' ', util.wrap(para, width)),
                              width, initindent, hangindent) + rest
                    for para, rest in findparas()])

@templatefilter('fill68')
def fill68(text):
    """Any text. Wraps the text to fit in 68 columns."""
    return fill(text, 68)

@templatefilter('fill76')
def fill76(text):
    """Any text. Wraps the text to fit in 76 columns."""
    return fill(text, 76)

@templatefilter('firstline')
def firstline(text):
    """Any text. Returns the first line of text."""
    try:
        return text.splitlines(True)[0].rstrip('\r\n')
    except IndexError:
        return ''

@templatefilter('hex')
def hexfilter(text):
    """Any text. Convert a binary Mercurial node identifier into
    its long hexadecimal representation.
    """
    return node.hex(text)

@templatefilter('hgdate')
def hgdate(text):
    """Date. Returns the date as a pair of numbers: "1157407993
    25200" (Unix timestamp, timezone offset).
    """
    return "%d %d" % text

@templatefilter('isodate')
def isodate(text):
    """Date. Returns the date in ISO 8601 format: "2009-08-18 13:00
    +0200".
    """
    return util.datestr(text, '%Y-%m-%d %H:%M %1%2')

@templatefilter('isodatesec')
def isodatesec(text):
    """Date. Returns the date in ISO 8601 format, including
    seconds: "2009-08-18 13:00:13 +0200". See also the rfc3339date
    filter.
    """
    return util.datestr(text, '%Y-%m-%d %H:%M:%S %1%2')

def indent(text, prefix):
    '''indent each non-empty line of text after first with prefix.'''
    lines = text.splitlines()
    num_lines = len(lines)
    endswithnewline = text[-1:] == '\n'
    def indenter():
        for i in xrange(num_lines):
            l = lines[i]
            if i and l.strip():
                yield prefix
            yield l
            if i < num_lines - 1 or endswithnewline:
                yield '\n'
    return "".join(indenter())

@templatefilter('json')
def json(obj, paranoid=True):
    if obj is None:
        return 'null'
    elif obj is False:
        return 'false'
    elif obj is True:
        return 'true'
    elif isinstance(obj, (int, long, float)):
        return pycompat.bytestr(obj)
    elif isinstance(obj, bytes):
        return '"%s"' % encoding.jsonescape(obj, paranoid=paranoid)
    elif isinstance(obj, str):
        # This branch is unreachable on Python 2, because bytes == str
        # and we'll return in the next-earlier block in the elif
        # ladder. On Python 3, this helps us catch bugs before they
        # hurt someone.
        raise error.ProgrammingError(
            'Mercurial only does output with bytes on Python 3: %r' % obj)
    elif util.safehasattr(obj, 'keys'):
        out = ['"%s": %s' % (encoding.jsonescape(k, paranoid=paranoid),
                             json(v, paranoid))
               for k, v in sorted(obj.iteritems())]
        return '{' + ', '.join(out) + '}'
    elif util.safehasattr(obj, '__iter__'):
        out = [json(i, paranoid) for i in obj]
        return '[' + ', '.join(out) + ']'
    else:
        raise TypeError('cannot encode type %s' % obj.__class__.__name__)

@templatefilter('lower')
def lower(text):
    """Any text. Converts the text to lowercase."""
    return encoding.lower(text)

@templatefilter('nonempty')
def nonempty(str):
    """Any text. Returns '(none)' if the string is empty."""
    return str or "(none)"

@templatefilter('obfuscate')
def obfuscate(text):
    """Any text. Returns the input text rendered as a sequence of
    XML entities.
    """
    text = unicode(text, encoding.encoding, 'replace')
    return ''.join(['&#%d;' % ord(c) for c in text])

@templatefilter('permissions')
def permissions(flags):
    if "l" in flags:
        return "lrwxrwxrwx"
    if "x" in flags:
        return "-rwxr-xr-x"
    return "-rw-r--r--"

@templatefilter('person')
def person(author):
    """Any text. Returns the name before an email address,
    interpreting it as per RFC 5322.

    >>> person(b'foo@bar')
    'foo'
    >>> person(b'Foo Bar <foo@bar>')
    'Foo Bar'
    >>> person(b'"Foo Bar" <foo@bar>')
    'Foo Bar'
    >>> person(b'"Foo \"buz\" Bar" <foo@bar>')
    'Foo "buz" Bar'
    >>> # The following are invalid, but do exist in real-life
    ...
    >>> person(b'Foo "buz" Bar <foo@bar>')
    'Foo "buz" Bar'
    >>> person(b'"Foo Bar <foo@bar>')
    'Foo Bar'
    """
    if '@' not in author:
        return author
    f = author.find('<')
    if f != -1:
        return author[:f].strip(' "').replace('\\"', '"')
    f = author.find('@')
    return author[:f].replace('.', ' ')

@templatefilter('revescape')
def revescape(text):
    """Any text. Escapes all "special" characters, except @.
    Forward slashes are escaped twice to prevent web servers from prematurely
    unescaping them. For example, "@foo bar/baz" becomes "@foo%20bar%252Fbaz".
    """
    return urlreq.quote(text, safe='/@').replace('/', '%252F')

@templatefilter('rfc3339date')
def rfc3339date(text):
    """Date. Returns a date using the Internet date format
    specified in RFC 3339: "2009-08-18T13:00:13+02:00".
    """
    return util.datestr(text, "%Y-%m-%dT%H:%M:%S%1:%2")

@templatefilter('rfc822date')
def rfc822date(text):
    """Date. Returns a date using the same format used in email
    headers: "Tue, 18 Aug 2009 13:00:13 +0200".
    """
    return util.datestr(text, "%a, %d %b %Y %H:%M:%S %1%2")

@templatefilter('short')
def short(text):
    """Changeset hash. Returns the short form of a changeset hash,
    i.e. a 12 hexadecimal digit string.
    """
    return text[:12]

@templatefilter('shortbisect')
def shortbisect(text):
    """Any text. Treats `text` as a bisection status, and
    returns a single-character representing the status (G: good, B: bad,
    S: skipped, U: untested, I: ignored). Returns single space if `text`
    is not a valid bisection status.
    """
    return hbisect.shortlabel(text) or ' '

@templatefilter('shortdate')
def shortdate(text):
    """Date. Returns a date like "2006-09-18"."""
    return util.shortdate(text)

@templatefilter('splitlines')
def splitlines(text):
    """Any text. Split text into a list of lines."""
    return templatekw.hybridlist(text.splitlines(), name='line')

@templatefilter('stringescape')
def stringescape(text):
    return util.escapestr(text)

@templatefilter('stringify')
def stringify(thing):
    """Any type. Turns the value into text by converting values into
    text and concatenating them.
    """
    thing = templatekw.unwraphybrid(thing)
    if util.safehasattr(thing, '__iter__') and not isinstance(thing, bytes):
        return "".join([stringify(t) for t in thing if t is not None])
    if thing is None:
        return ""
    return pycompat.bytestr(thing)

@templatefilter('stripdir')
def stripdir(text):
    """Treat the text as path and strip a directory level, if
    possible. For example, "foo" and "foo/bar" becomes "foo".
    """
    dir = os.path.dirname(text)
    if dir == "":
        return os.path.basename(text)
    else:
        return dir

@templatefilter('tabindent')
def tabindent(text):
    """Any text. Returns the text, with every non-empty line
    except the first starting with a tab character.
    """
    return indent(text, '\t')

@templatefilter('upper')
def upper(text):
    """Any text. Converts the text to uppercase."""
    return encoding.upper(text)

@templatefilter('urlescape')
def urlescape(text):
    """Any text. Escapes all "special" characters. For example,
    "foo bar" becomes "foo%20bar".
    """
    return urlreq.quote(text)

@templatefilter('user')
def userfilter(text):
    """Any text. Returns a short representation of a user name or email
    address."""
    return util.shortuser(text)

@templatefilter('emailuser')
def emailuser(text):
    """Any text. Returns the user portion of an email address."""
    return util.emailuser(text)

@templatefilter('utf8')
def utf8(text):
    """Any text. Converts from the local character encoding to UTF-8."""
    return encoding.fromlocal(text)

@templatefilter('xmlescape')
def xmlescape(text):
    text = (text
            .replace('&', '&amp;')
            .replace('<', '&lt;')
            .replace('>', '&gt;')
            .replace('"', '&quot;')
            .replace("'", '&#39;')) # &apos; invalid in HTML
    return re.sub('[\x00-\x08\x0B\x0C\x0E-\x1F]', ' ', text)

def websub(text, websubtable):
    """:websub: Any text. Only applies to hgweb. Applies the regular
    expression replacements defined in the websub section.
    """
    if websubtable:
        for regexp, format in websubtable:
            text = regexp.sub(format, text)
    return text

def loadfilter(ui, extname, registrarobj):
    """Load template filter from specified registrarobj
    """
    for name, func in registrarobj._table.iteritems():
        filters[name] = func

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