Mercurial > hg
view mercurial/templatefilters.py @ 26623:5a95fe44121d
clonebundles: support for seeding clones from pre-generated bundles
Cloning can be an expensive operation for servers because the server
generates a bundle from existing repository data at request time. For
a large repository like mozilla-central, this consumes 4+ minutes
of CPU time on the server. It also results in significant network
utilization. Multiplied by hundreds or even thousands of clients and
the ensuing load can result in difficulties scaling the Mercurial server.
Despite generation of bundles being deterministic until the next
changeset is added, the generation of bundles to service a clone request
is not cached. Each clone thus performs redundant work. This is
wasteful.
This patch introduces the "clonebundles" extension and related
client-side functionality to help alleviate this deficiency. The
client-side feature is behind an experimental flag and is not enabled by
default.
It works as follows:
1) Server operator generates a bundle and makes it available on a
server (likely HTTP).
2) Server operator defines the URL of a bundle file in a
.hg/clonebundles.manifest file.
3) Client `hg clone`ing sees the server is advertising bundle URLs.
4) Client fetches and applies the advertised bundle.
5) Client performs equivalent of `hg pull` to fetch changes made since
the bundle was created.
Essentially, the server performs the expensive work of generating a
bundle once and all subsequent clones fetch a static file from
somewhere. Scaling static file serving is a much more manageable
problem than scaling a Python application like Mercurial. Assuming your
repository grows less than 1% per day, the end result is 99+% of CPU
and network load from clones is eliminated, allowing Mercurial servers
to scale more easily. Serving static files also means data can be
transferred to clients as fast as they can consume it, rather than as
fast as servers can generate it. This makes clones faster.
Mozilla has implemented similar functionality of this patch on
hg.mozilla.org using a custom extension. We are hosting bundle files in
Amazon S3 and CloudFront (a CDN) and have successfully offloaded
>1 TB/day in data transfer from hg.mozilla.org, freeing up significant
bandwidth and CPU resources. The positive impact has been stellar and
I believe it has proved its value to be included in Mercurial core. I
feel it is important for the client-side support to be enabled in core
by default because it means that clients will get faster, more reliable
clones and will enable server operators to reduce load without
requiring any client-side configuration changes (assuming clients are
up to date, of course).
The scope of this feature is narrowly and specifically tailored to
cloning, despite "serve pulls from pre-generated bundles" being a valid
and useful feature. I would eventually like for Mercurial servers to
support transferring *all* repository data via statically hosted files.
You could imagine a server that siphons all pushed data to bundle files
and instructs clients to apply a stream of bundles to reconstruct all
repository data. This feature, while useful and powerful, is
significantly more work to implement because it requires the server
component have awareness of discovery and a mapping of which changesets
are in which files. Full, clone bundles, by contrast, are much simpler.
The wire protocol command is named "clonebundles" instead of something
more generic like "staticbundles" to leave the door open for a new, more
powerful and more generic server-side component with minimal backwards
compatibility implications. The name "bundleclone" is used by Mozilla's
extension and would cause problems since there are subtle differences
in Mozilla's extension.
Mozilla's experience with this idea has taught us that some form of
"content negotiation" is required. Not all clients will support all
bundle formats or even URLs (advanced TLS requirements, etc). To ensure
the highest uptake possible, a server needs to advertise multiple
versions of bundles and clients need to be able to choose the most
appropriate from that list one. The "attributes" in each
server-advertised entry facilitate this filtering and sorting. Their
use will become apparent in subsequent patches.
Initial inspiration and credit for the idea of cloning from static files
belongs to Augie Fackler and his "lookaside clone" extension proof of
concept.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 09 Oct 2015 11:22:01 -0700 |
parents | 7012be5ab5bd |
children | f580c78ea667 baa77652be68 |
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# template-filters.py - common template expansion filters # # Copyright 2005-2008 Matt Mackall <mpm@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 cgi import os import re import time import urllib from . import ( encoding, hbisect, node, templatekw, util, ) def addbreaks(text): """:addbreaks: 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')] def age(date, abbrev=False): """:age: 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) def basename(path): """:basename: 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) def count(i): """:count: List or text. Returns the length as an integer.""" return len(i) def domain(author): """:domain: Any text. Finds the first string that looks like an email address, and extracts just the domain component. Example: ``User <user@example.com>`` 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 def email(text): """:email: Any text. Extracts the first string that looks like an email address. Example: ``User <user@example.com>`` becomes ``user@example.com``. """ return util.email(text) def escape(text): """:escape: Any text. Replaces the special XML/XHTML characters "&", "<" and ">" with XML entities, and filters out NUL characters. """ return cgi.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()]) def fill68(text): """:fill68: Any text. Wraps the text to fit in 68 columns.""" return fill(text, 68) def fill76(text): """:fill76: Any text. Wraps the text to fit in 76 columns.""" return fill(text, 76) def firstline(text): """:firstline: Any text. Returns the first line of text.""" try: return text.splitlines(True)[0].rstrip('\r\n') except IndexError: return '' def hexfilter(text): """:hex: Any text. Convert a binary Mercurial node identifier into its long hexadecimal representation. """ return node.hex(text) def hgdate(text): """:hgdate: Date. Returns the date as a pair of numbers: "1157407993 25200" (Unix timestamp, timezone offset). """ return "%d %d" % text def isodate(text): """:isodate: 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') def isodatesec(text): """:isodatesec: 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()) def json(obj): if obj is None or obj is False or obj is True: return {None: 'null', False: 'false', True: 'true'}[obj] elif isinstance(obj, int) or isinstance(obj, float): return str(obj) elif isinstance(obj, str): u = unicode(obj, encoding.encoding, 'replace') return '"%s"' % jsonescape(u) elif isinstance(obj, unicode): return '"%s"' % jsonescape(obj) elif util.safehasattr(obj, 'keys'): out = [] for k, v in sorted(obj.iteritems()): s = '%s: %s' % (json(k), json(v)) out.append(s) return '{' + ', '.join(out) + '}' elif util.safehasattr(obj, '__iter__'): out = [] for i in obj: out.append(json(i)) return '[' + ', '.join(out) + ']' elif util.safehasattr(obj, '__call__'): return json(obj()) else: raise TypeError('cannot encode type %s' % obj.__class__.__name__) def _uescape(c): if ord(c) < 0x80: return c else: return '\\u%04x' % ord(c) _escapes = [ ('\\', '\\\\'), ('"', '\\"'), ('\t', '\\t'), ('\n', '\\n'), ('\r', '\\r'), ('\f', '\\f'), ('\b', '\\b'), ('<', '\\u003c'), ('>', '\\u003e'), ('\0', '\\u0000') ] def jsonescape(s): for k, v in _escapes: s = s.replace(k, v) return ''.join(_uescape(c) for c in s) def lower(text): """:lower: Any text. Converts the text to lowercase.""" return encoding.lower(text) def nonempty(str): """:nonempty: Any text. Returns '(none)' if the string is empty.""" return str or "(none)" def obfuscate(text): """:obfuscate: 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]) def permissions(flags): if "l" in flags: return "lrwxrwxrwx" if "x" in flags: return "-rwxr-xr-x" return "-rw-r--r--" def person(author): """:person: Any text. Returns the name before an email address, interpreting it as per RFC 5322. >>> person('foo@bar') 'foo' >>> person('Foo Bar <foo@bar>') 'Foo Bar' >>> person('"Foo Bar" <foo@bar>') 'Foo Bar' >>> person('"Foo \"buz\" Bar" <foo@bar>') 'Foo "buz" Bar' >>> # The following are invalid, but do exist in real-life ... >>> person('Foo "buz" Bar <foo@bar>') 'Foo "buz" Bar' >>> person('"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('.', ' ') def revescape(text): """:revescape: 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 urllib.quote(text, safe='/@').replace('/', '%252F') def rfc3339date(text): """:rfc3339date: 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") def rfc822date(text): """:rfc822date: 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") def short(text): """:short: Changeset hash. Returns the short form of a changeset hash, i.e. a 12 hexadecimal digit string. """ return text[:12] def shortbisect(text): """:shortbisect: 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 ' ' def shortdate(text): """:shortdate: Date. Returns a date like "2006-09-18".""" return util.shortdate(text) def splitlines(text): """:splitlines: Any text. Split text into a list of lines.""" return templatekw.showlist('line', text.splitlines(), 'lines') def stringescape(text): return text.encode('string_escape') def stringify(thing): """:stringify: Any type. Turns the value into text by converting values into text and concatenating them. """ if util.safehasattr(thing, '__iter__') and not isinstance(thing, str): return "".join([stringify(t) for t in thing if t is not None]) if thing is None: return "" return str(thing) def stripdir(text): """:stripdir: 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 def tabindent(text): """:tabindent: Any text. Returns the text, with every non-empty line except the first starting with a tab character. """ return indent(text, '\t') def upper(text): """:upper: Any text. Converts the text to uppercase.""" return encoding.upper(text) def urlescape(text): """:urlescape: Any text. Escapes all "special" characters. For example, "foo bar" becomes "foo%20bar". """ return urllib.quote(text) def userfilter(text): """:user: Any text. Returns a short representation of a user name or email address.""" return util.shortuser(text) def emailuser(text): """:emailuser: Any text. Returns the user portion of an email address.""" return util.emailuser(text) def xmlescape(text): text = (text .replace('&', '&') .replace('<', '<') .replace('>', '>') .replace('"', '"') .replace("'", ''')) # ' invalid in HTML return re.sub('[\x00-\x08\x0B\x0C\x0E-\x1F]', ' ', text) filters = { "addbreaks": addbreaks, "age": age, "basename": basename, "count": count, "domain": domain, "email": email, "escape": escape, "fill68": fill68, "fill76": fill76, "firstline": firstline, "hex": hexfilter, "hgdate": hgdate, "isodate": isodate, "isodatesec": isodatesec, "json": json, "jsonescape": jsonescape, "lower": lower, "nonempty": nonempty, "obfuscate": obfuscate, "permissions": permissions, "person": person, "revescape": revescape, "rfc3339date": rfc3339date, "rfc822date": rfc822date, "short": short, "shortbisect": shortbisect, "shortdate": shortdate, "splitlines": splitlines, "stringescape": stringescape, "stringify": stringify, "stripdir": stripdir, "tabindent": tabindent, "upper": upper, "urlescape": urlescape, "user": userfilter, "emailuser": emailuser, "xmlescape": xmlescape, } 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 # tell hggettext to extract docstrings from these functions: i18nfunctions = filters.values()