view hgext/gpg.py @ 26380:56a640b0f656

revlog: don't flush data file after every added revision

The current behavior of revlogs is to flush the data file when writing
data to it. Tracing system calls revealed that changegroup processing
incurred numerous write(2) calls for values much smaller than the
default buffer size (Python defaults to 4096, but it can be adjusted
based on detected block size at run time by CPython).

The reason we flush revlogs is so readers have all data available.
For example, the current code in revlog.py will re-open the revlog
file (instead of seeking an existing file handle) to read the text
of a revision. This happens when starting a new delta chain when
adding several revisions from changegroups, for example. Yes, this
is likely sub-optimal (we should probably be sharing file descriptors
between readers and writers to avoid the flushing and associated
overhead of re-opening files).

While flushing revlogs is necessary, it appears all callers are
diligent about flushing files before a read is performed (see
buildtext() in _addrevision()), making the flush in
_writeentry() redundant and unncessary. So, we remove it. In practice,
this means we incur a write(2) a) when the buffer is full (typically
4096 bytes) b) when a new delta chain is created rather than after
every added revision. This applies to every revlog, but by volume
it mostly impacts filelogs.

Removing the redundant flush from _writeentry() significantly
reduces the number of write(2) calls during changegroup processing on
my Linux machine. When applying a changegroup of the hg repo based on
my local repo, the total number of write(2) calls during application
of the mercurial/localrepo.py revlogs dropped from 1,320 to 217 with
this patch applied. Total I/O related system calls dropped from 1,577
to 474.

When unbundling a mozilla-central gzipped bundle (264,403 changesets
with 1,492,215 changes to 222,507 files), total write(2) calls
dropped from 1,252,881 to 827,106 and total system calls dropped from
3,601,259 to 3,178,636 - a reduction of 425,775!

While the system call reduction is significant, it appears
to have no impact on wall time on my Linux and Windows machines. Still,
fewer syscalls is fewer syscalls. Surely this can't hurt. If nothing
else, it makes examining remaining system call usage simpler and opens
the door to experimenting with the performance impact of different
buffer sizes.

# Copyright 2005, 2006 Benoit Boissinot <[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.

'''commands to sign and verify changesets'''

import os, tempfile, binascii
from mercurial import util, commands, match, cmdutil
from mercurial import node as hgnode
from mercurial.i18n import _

cmdtable = {}
command = cmdutil.command(cmdtable)
# Note for extension authors: ONLY specify testedwith = 'internal' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'internal'

class gpg(object):
    def __init__(self, path, key=None):
        self.path = path
        self.key = (key and " --local-user \"%s\"" % key) or ""

    def sign(self, data):
        gpgcmd = "%s --sign --detach-sign%s" % (self.path, self.key)
        return util.filter(data, gpgcmd)

    def verify(self, data, sig):
        """ returns of the good and bad signatures"""
        sigfile = datafile = None
        try:
            # create temporary files
            fd, sigfile = tempfile.mkstemp(prefix="hg-gpg-", suffix=".sig")
            fp = os.fdopen(fd, 'wb')
            fp.write(sig)
            fp.close()
            fd, datafile = tempfile.mkstemp(prefix="hg-gpg-", suffix=".txt")
            fp = os.fdopen(fd, 'wb')
            fp.write(data)
            fp.close()
            gpgcmd = ("%s --logger-fd 1 --status-fd 1 --verify "
                      "\"%s\" \"%s\"" % (self.path, sigfile, datafile))
            ret = util.filter("", gpgcmd)
        finally:
            for f in (sigfile, datafile):
                try:
                    if f:
                        os.unlink(f)
                except OSError:
                    pass
        keys = []
        key, fingerprint = None, None
        for l in ret.splitlines():
            # see DETAILS in the gnupg documentation
            # filter the logger output
            if not l.startswith("[GNUPG:]"):
                continue
            l = l[9:]
            if l.startswith("VALIDSIG"):
                # fingerprint of the primary key
                fingerprint = l.split()[10]
            elif l.startswith("ERRSIG"):
                key = l.split(" ", 3)[:2]
                key.append("")
                fingerprint = None
            elif (l.startswith("GOODSIG") or
                  l.startswith("EXPSIG") or
                  l.startswith("EXPKEYSIG") or
                  l.startswith("BADSIG")):
                if key is not None:
                    keys.append(key + [fingerprint])
                key = l.split(" ", 2)
                fingerprint = None
        if key is not None:
            keys.append(key + [fingerprint])
        return keys

def newgpg(ui, **opts):
    """create a new gpg instance"""
    gpgpath = ui.config("gpg", "cmd", "gpg")
    gpgkey = opts.get('key')
    if not gpgkey:
        gpgkey = ui.config("gpg", "key", None)
    return gpg(gpgpath, gpgkey)

def sigwalk(repo):
    """
    walk over every sigs, yields a couple
    ((node, version, sig), (filename, linenumber))
    """
    def parsefile(fileiter, context):
        ln = 1
        for l in fileiter:
            if not l:
                continue
            yield (l.split(" ", 2), (context, ln))
            ln += 1

    # read the heads
    fl = repo.file(".hgsigs")
    for r in reversed(fl.heads()):
        fn = ".hgsigs|%s" % hgnode.short(r)
        for item in parsefile(fl.read(r).splitlines(), fn):
            yield item
    try:
        # read local signatures
        fn = "localsigs"
        for item in parsefile(repo.vfs(fn), fn):
            yield item
    except IOError:
        pass

def getkeys(ui, repo, mygpg, sigdata, context):
    """get the keys who signed a data"""
    fn, ln = context
    node, version, sig = sigdata
    prefix = "%s:%d" % (fn, ln)
    node = hgnode.bin(node)

    data = node2txt(repo, node, version)
    sig = binascii.a2b_base64(sig)
    keys = mygpg.verify(data, sig)

    validkeys = []
    # warn for expired key and/or sigs
    for key in keys:
        if key[0] == "ERRSIG":
            ui.write(_("%s Unknown key ID \"%s\"\n")
                     % (prefix, shortkey(ui, key[1][:15])))
            continue
        if key[0] == "BADSIG":
            ui.write(_("%s Bad signature from \"%s\"\n") % (prefix, key[2]))
            continue
        if key[0] == "EXPSIG":
            ui.write(_("%s Note: Signature has expired"
                       " (signed by: \"%s\")\n") % (prefix, key[2]))
        elif key[0] == "EXPKEYSIG":
            ui.write(_("%s Note: This key has expired"
                       " (signed by: \"%s\")\n") % (prefix, key[2]))
        validkeys.append((key[1], key[2], key[3]))
    return validkeys

@command("sigs", [], _('hg sigs'))
def sigs(ui, repo):
    """list signed changesets"""
    mygpg = newgpg(ui)
    revs = {}

    for data, context in sigwalk(repo):
        node, version, sig = data
        fn, ln = context
        try:
            n = repo.lookup(node)
        except KeyError:
            ui.warn(_("%s:%d node does not exist\n") % (fn, ln))
            continue
        r = repo.changelog.rev(n)
        keys = getkeys(ui, repo, mygpg, data, context)
        if not keys:
            continue
        revs.setdefault(r, [])
        revs[r].extend(keys)
    for rev in sorted(revs, reverse=True):
        for k in revs[rev]:
            r = "%5d:%s" % (rev, hgnode.hex(repo.changelog.node(rev)))
            ui.write("%-30s %s\n" % (keystr(ui, k), r))

@command("sigcheck", [], _('hg sigcheck REV'))
def check(ui, repo, rev):
    """verify all the signatures there may be for a particular revision"""
    mygpg = newgpg(ui)
    rev = repo.lookup(rev)
    hexrev = hgnode.hex(rev)
    keys = []

    for data, context in sigwalk(repo):
        node, version, sig = data
        if node == hexrev:
            k = getkeys(ui, repo, mygpg, data, context)
            if k:
                keys.extend(k)

    if not keys:
        ui.write(_("no valid signature for %s\n") % hgnode.short(rev))
        return

    # print summary
    ui.write("%s is signed by:\n" % hgnode.short(rev))
    for key in keys:
        ui.write(" %s\n" % keystr(ui, key))

def keystr(ui, key):
    """associate a string to a key (username, comment)"""
    keyid, user, fingerprint = key
    comment = ui.config("gpg", fingerprint, None)
    if comment:
        return "%s (%s)" % (user, comment)
    else:
        return user

@command("sign",
         [('l', 'local', None, _('make the signature local')),
          ('f', 'force', None, _('sign even if the sigfile is modified')),
          ('', 'no-commit', None, _('do not commit the sigfile after signing')),
          ('k', 'key', '',
           _('the key id to sign with'), _('ID')),
          ('m', 'message', '',
           _('use text as commit message'), _('TEXT')),
          ('e', 'edit', False, _('invoke editor on commit messages')),
         ] + commands.commitopts2,
         _('hg sign [OPTION]... [REV]...'))
def sign(ui, repo, *revs, **opts):
    """add a signature for the current or given revision

    If no revision is given, the parent of the working directory is used,
    or tip if no revision is checked out.

    The ``gpg.cmd`` config setting can be used to specify the command
    to run. A default key can be specified with ``gpg.key``.

    See :hg:`help dates` for a list of formats valid for -d/--date.
    """

    mygpg = newgpg(ui, **opts)
    sigver = "0"
    sigmessage = ""

    date = opts.get('date')
    if date:
        opts['date'] = util.parsedate(date)

    if revs:
        nodes = [repo.lookup(n) for n in revs]
    else:
        nodes = [node for node in repo.dirstate.parents()
                 if node != hgnode.nullid]
        if len(nodes) > 1:
            raise util.Abort(_('uncommitted merge - please provide a '
                               'specific revision'))
        if not nodes:
            nodes = [repo.changelog.tip()]

    for n in nodes:
        hexnode = hgnode.hex(n)
        ui.write(_("signing %d:%s\n") % (repo.changelog.rev(n),
                                         hgnode.short(n)))
        # build data
        data = node2txt(repo, n, sigver)
        sig = mygpg.sign(data)
        if not sig:
            raise util.Abort(_("error while signing"))
        sig = binascii.b2a_base64(sig)
        sig = sig.replace("\n", "")
        sigmessage += "%s %s %s\n" % (hexnode, sigver, sig)

    # write it
    if opts['local']:
        repo.vfs.append("localsigs", sigmessage)
        return

    if not opts["force"]:
        msigs = match.exact(repo.root, '', ['.hgsigs'])
        if any(repo.status(match=msigs, unknown=True, ignored=True)):
            raise util.Abort(_("working copy of .hgsigs is changed "),
                             hint=_("please commit .hgsigs manually"))

    sigsfile = repo.wfile(".hgsigs", "ab")
    sigsfile.write(sigmessage)
    sigsfile.close()

    if '.hgsigs' not in repo.dirstate:
        repo[None].add([".hgsigs"])

    if opts["no_commit"]:
        return

    message = opts['message']
    if not message:
        # we don't translate commit messages
        message = "\n".join(["Added signature for changeset %s"
                             % hgnode.short(n)
                             for n in nodes])
    try:
        editor = cmdutil.getcommiteditor(editform='gpg.sign', **opts)
        repo.commit(message, opts['user'], opts['date'], match=msigs,
                    editor=editor)
    except ValueError as inst:
        raise util.Abort(str(inst))

def shortkey(ui, key):
    if len(key) != 16:
        ui.debug("key ID \"%s\" format error\n" % key)
        return key

    return key[-8:]

def node2txt(repo, node, ver):
    """map a manifest into some text"""
    if ver == "0":
        return "%s\n" % hgnode.hex(node)
    else:
        raise util.Abort(_("unknown signature version"))