view hgext/convert/monotone.py @ 30212:260af19891f2

changegroup: increase write buffer size to 128k

By default, Python defers to the operating system for choosing the
default buffer size on opened files. On my Linux machine, the default
is 4k, which is really small for 2016.

This patch bumps the write buffer size when writing
changegroups/bundles to 128k. This matches the 128k read buffer
we already use on revlogs.

It's worth noting that this only impacts when writing to an explicit
file (such as during `hg bundle`). Buffers when writing to bundle
files via the repo vfs or to a temporary file are not impacted.

When producing a none-v2 bundle file of the mozilla-unified repository,
this change caused the number of write() system calls to drop from
952,449 to 29,788. After this change, the most frequent system
calls are fstat(), read(), lseek(), and open(). There were
2,523,672 system calls after this patch (so a net decrease of
~950k is statistically significant).

This change shows no performance change on my system. But I have a
high-end system with a fast SSD. It is quite possible this change
will have a significant impact on network file systems, where
extra network round trips due to excessive I/O system calls could
introduce significant latency.

# monotone.py - monotone support for the convert extension
#
#  Copyright 2008, 2009 Mikkel Fahnoe Jorgensen <[e-mail]> and
#  others
#
# 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

from mercurial.i18n import _
from mercurial import (
    error,
    util,
)

from . import common

class monotone_source(common.converter_source, common.commandline):
    def __init__(self, ui, path=None, revs=None):
        common.converter_source.__init__(self, ui, path, revs)
        if revs and len(revs) > 1:
            raise error.Abort(_('monotone source does not support specifying '
                               'multiple revs'))
        common.commandline.__init__(self, ui, 'mtn')

        self.ui = ui
        self.path = path
        self.automatestdio = False
        self.revs = revs

        norepo = common.NoRepo(_("%s does not look like a monotone repository")
                             % path)
        if not os.path.exists(os.path.join(path, '_MTN')):
            # Could be a monotone repository (SQLite db file)
            try:
                f = file(path, 'rb')
                header = f.read(16)
                f.close()
            except IOError:
                header = ''
            if header != 'SQLite format 3\x00':
                raise norepo

        # regular expressions for parsing monotone output
        space    = r'\s*'
        name     = r'\s+"((?:\\"|[^"])*)"\s*'
        value    = name
        revision = r'\s+\[(\w+)\]\s*'
        lines    = r'(?:.|\n)+'

        self.dir_re      = re.compile(space + "dir" + name)
        self.file_re     = re.compile(space + "file" + name +
                                      "content" + revision)
        self.add_file_re = re.compile(space + "add_file" + name +
                                      "content" + revision)
        self.patch_re    = re.compile(space + "patch" + name +
                                      "from" + revision + "to" + revision)
        self.rename_re   = re.compile(space + "rename" + name + "to" + name)
        self.delete_re   = re.compile(space + "delete" + name)
        self.tag_re      = re.compile(space + "tag" + name + "revision" +
                                      revision)
        self.cert_re     = re.compile(lines + space + "name" + name +
                                      "value" + value)

        attr = space + "file" + lines + space + "attr" + space
        self.attr_execute_re = re.compile(attr  + '"mtn:execute"' +
                                          space + '"true"')

        # cached data
        self.manifest_rev = None
        self.manifest = None
        self.files = None
        self.dirs  = None

        common.checktool('mtn', abort=False)

    def mtnrun(self, *args, **kwargs):
        if self.automatestdio:
            return self.mtnrunstdio(*args, **kwargs)
        else:
            return self.mtnrunsingle(*args, **kwargs)

    def mtnrunsingle(self, *args, **kwargs):
        kwargs['d'] = self.path
        return self.run0('automate', *args, **kwargs)

    def mtnrunstdio(self, *args, **kwargs):
        # Prepare the command in automate stdio format
        command = []
        for k, v in kwargs.iteritems():
            command.append("%s:%s" % (len(k), k))
            if v:
                command.append("%s:%s" % (len(v), v))
        if command:
            command.insert(0, 'o')
            command.append('e')

        command.append('l')
        for arg in args:
            command += "%s:%s" % (len(arg), arg)
        command.append('e')
        command = ''.join(command)

        self.ui.debug("mtn: sending '%s'\n" % command)
        self.mtnwritefp.write(command)
        self.mtnwritefp.flush()

        return self.mtnstdioreadcommandoutput(command)

    def mtnstdioreadpacket(self):
        read = None
        commandnbr = ''
        while read != ':':
            read = self.mtnreadfp.read(1)
            if not read:
                raise error.Abort(_('bad mtn packet - no end of commandnbr'))
            commandnbr += read
        commandnbr = commandnbr[:-1]

        stream = self.mtnreadfp.read(1)
        if stream not in 'mewptl':
            raise error.Abort(_('bad mtn packet - bad stream type %s') % stream)

        read = self.mtnreadfp.read(1)
        if read != ':':
            raise error.Abort(_('bad mtn packet - no divider before size'))

        read = None
        lengthstr = ''
        while read != ':':
            read = self.mtnreadfp.read(1)
            if not read:
                raise error.Abort(_('bad mtn packet - no end of packet size'))
            lengthstr += read
        try:
            length = long(lengthstr[:-1])
        except TypeError:
            raise error.Abort(_('bad mtn packet - bad packet size %s')
                % lengthstr)

        read = self.mtnreadfp.read(length)
        if len(read) != length:
            raise error.Abort(_("bad mtn packet - unable to read full packet "
                "read %s of %s") % (len(read), length))

        return (commandnbr, stream, length, read)

    def mtnstdioreadcommandoutput(self, command):
        retval = []
        while True:
            commandnbr, stream, length, output = self.mtnstdioreadpacket()
            self.ui.debug('mtn: read packet %s:%s:%s\n' %
                (commandnbr, stream, length))

            if stream == 'l':
                # End of command
                if output != '0':
                    raise error.Abort(_("mtn command '%s' returned %s") %
                        (command, output))
                break
            elif stream in 'ew':
                # Error, warning output
                self.ui.warn(_('%s error:\n') % self.command)
                self.ui.warn(output)
            elif stream == 'p':
                # Progress messages
                self.ui.debug('mtn: ' + output)
            elif stream == 'm':
                # Main stream - command output
                retval.append(output)

        return ''.join(retval)

    def mtnloadmanifest(self, rev):
        if self.manifest_rev == rev:
            return
        self.manifest = self.mtnrun("get_manifest_of", rev).split("\n\n")
        self.manifest_rev = rev
        self.files = {}
        self.dirs = {}

        for e in self.manifest:
            m = self.file_re.match(e)
            if m:
                attr = ""
                name = m.group(1)
                node = m.group(2)
                if self.attr_execute_re.match(e):
                    attr += "x"
                self.files[name] = (node, attr)
            m = self.dir_re.match(e)
            if m:
                self.dirs[m.group(1)] = True

    def mtnisfile(self, name, rev):
        # a non-file could be a directory or a deleted or renamed file
        self.mtnloadmanifest(rev)
        return name in self.files

    def mtnisdir(self, name, rev):
        self.mtnloadmanifest(rev)
        return name in self.dirs

    def mtngetcerts(self, rev):
        certs = {"author":"<missing>", "date":"<missing>",
            "changelog":"<missing>", "branch":"<missing>"}
        certlist = self.mtnrun("certs", rev)
        # mtn < 0.45:
        #   key "[e-mail]"
        # mtn >= 0.45:
        #   key [ff58a7ffb771907c4ff68995eada1c4da068d328]
        certlist = re.split('\n\n      key ["\[]', certlist)
        for e in certlist:
            m = self.cert_re.match(e)
            if m:
                name, value = m.groups()
                value = value.replace(r'\"', '"')
                value = value.replace(r'\\', '\\')
                certs[name] = value
        # Monotone may have subsecond dates: 2005-02-05T09:39:12.364306
        # and all times are stored in UTC
        certs["date"] = certs["date"].split('.')[0] + " UTC"
        return certs

    # implement the converter_source interface:

    def getheads(self):
        if not self.revs:
            return self.mtnrun("leaves").splitlines()
        else:
            return self.revs

    def getchanges(self, rev, full):
        if full:
            raise error.Abort(_("convert from monotone does not support "
                              "--full"))
        revision = self.mtnrun("get_revision", rev).split("\n\n")
        files = {}
        ignoremove = {}
        renameddirs = []
        copies = {}
        for e in revision:
            m = self.add_file_re.match(e)
            if m:
                files[m.group(1)] = rev
                ignoremove[m.group(1)] = rev
            m = self.patch_re.match(e)
            if m:
                files[m.group(1)] = rev
            # Delete/rename is handled later when the convert engine
            # discovers an IOError exception from getfile,
            # but only if we add the "from" file to the list of changes.
            m = self.delete_re.match(e)
            if m:
                files[m.group(1)] = rev
            m = self.rename_re.match(e)
            if m:
                toname = m.group(2)
                fromname = m.group(1)
                if self.mtnisfile(toname, rev):
                    ignoremove[toname] = 1
                    copies[toname] = fromname
                    files[toname] = rev
                    files[fromname] = rev
                elif self.mtnisdir(toname, rev):
                    renameddirs.append((fromname, toname))

        # Directory renames can be handled only once we have recorded
        # all new files
        for fromdir, todir in renameddirs:
            renamed = {}
            for tofile in self.files:
                if tofile in ignoremove:
                    continue
                if tofile.startswith(todir + '/'):
                    renamed[tofile] = fromdir + tofile[len(todir):]
                    # Avoid chained moves like:
                    # d1(/a) => d3/d1(/a)
                    # d2 => d3
                    ignoremove[tofile] = 1
            for tofile, fromfile in renamed.items():
                self.ui.debug (_("copying file in renamed directory "
                                 "from '%s' to '%s'")
                               % (fromfile, tofile), '\n')
                files[tofile] = rev
                copies[tofile] = fromfile
            for fromfile in renamed.values():
                files[fromfile] = rev

        return (files.items(), copies, set())

    def getfile(self, name, rev):
        if not self.mtnisfile(name, rev):
            return None, None
        try:
            data = self.mtnrun("get_file_of", name, r=rev)
        except Exception:
            return None, None
        self.mtnloadmanifest(rev)
        node, attr = self.files.get(name, (None, ""))
        return data, attr

    def getcommit(self, rev):
        extra = {}
        certs = self.mtngetcerts(rev)
        if certs.get('suspend') == certs["branch"]:
            extra['close'] = 1
        return common.commit(
            author=certs["author"],
            date=util.datestr(util.strdate(certs["date"], "%Y-%m-%dT%H:%M:%S")),
            desc=certs["changelog"],
            rev=rev,
            parents=self.mtnrun("parents", rev).splitlines(),
            branch=certs["branch"],
            extra=extra)

    def gettags(self):
        tags = {}
        for e in self.mtnrun("tags").split("\n\n"):
            m = self.tag_re.match(e)
            if m:
                tags[m.group(1)] = m.group(2)
        return tags

    def getchangedfiles(self, rev, i):
        # This function is only needed to support --filemap
        # ... and we don't support that
        raise NotImplementedError

    def before(self):
        # Check if we have a new enough version to use automate stdio
        version = 0.0
        try:
            versionstr = self.mtnrunsingle("interface_version")
            version = float(versionstr)
        except Exception:
            raise error.Abort(_("unable to determine mtn automate interface "
                "version"))

        if version >= 12.0:
            self.automatestdio = True
            self.ui.debug("mtn automate version %s - using automate stdio\n" %
                version)

            # launch the long-running automate stdio process
            self.mtnwritefp, self.mtnreadfp = self._run2('automate', 'stdio',
                '-d', self.path)
            # read the headers
            read = self.mtnreadfp.readline()
            if read != 'format-version: 2\n':
                raise error.Abort(_('mtn automate stdio header unexpected: %s')
                    % read)
            while read != '\n':
                read = self.mtnreadfp.readline()
                if not read:
                    raise error.Abort(_("failed to reach end of mtn automate "
                        "stdio headers"))
        else:
            self.ui.debug("mtn automate version %s - not using automate stdio "
                "(automate >= 12.0 - mtn >= 0.46 is needed)\n" % version)

    def after(self):
        if self.automatestdio:
            self.mtnwritefp.close()
            self.mtnwritefp = None
            self.mtnreadfp.close()
            self.mtnreadfp = None