view hgext/convert/monotone.py @ 30817:2b279126b8f5

revlog: use compression engine APIs for decompression

Now that compression engines declare their header in revlog chunks
and can decompress revlog chunks, we refactor revlog.decompress()
to use them.

Making full use of the property that revlog compressor objects are
reusable, revlog instances now maintain a dict mapping an engine's
revlog header to a compressor object. This is not only a performance
optimization for engines where compressor object reuse can result in
better performance, but it also serves as a cache of header values
so we don't need to perform redundant lookups against the compression
engine manager. (Yes, I measured and the overhead of a function call
versus a dict lookup was observed.)

Replacing the previous inline lookup table with a dict lookup was
measured to make chunk reading ~2.5% slower on changelogs and ~4.5%
slower on manifests. So, the inline lookup table has been mostly
preserved so we don't lose performance. This is unfortunate. But
many decompression operations complete in microseconds, so Python
attribute lookup, dict lookup, and function calls do matter.

The impact of this change on mozilla-unified is as follows:

$ hg perfrevlogchunks -c
! chunk
! wall 1.953663 comb 1.950000 user 1.920000 sys 0.030000 (best of 6)
! wall 1.946000 comb 1.940000 user 1.910000 sys 0.030000 (best of 6)
! chunk batch
! wall 1.791075 comb 1.800000 user 1.760000 sys 0.040000 (best of 6)
! wall 1.785690 comb 1.770000 user 1.750000 sys 0.020000 (best of 6)

$ hg perfrevlogchunks -m
! chunk
! wall 2.587262 comb 2.580000 user 2.550000 sys 0.030000 (best of 4)
! wall 2.616330 comb 2.610000 user 2.560000 sys 0.050000 (best of 4)
! chunk batch
! wall 2.427092 comb 2.420000 user 2.400000 sys 0.020000 (best of 5)
! wall 2.462061 comb 2.460000 user 2.400000 sys 0.060000 (best of 4)

Changelog chunk reading is slightly faster but manifest reading is
slower. What gives?

On this repo, 99.85% of changelog entries are zlib compressed (the 'x'
header). On the manifest, 67.5% are zlib and 32.4% are '\0'. This patch
swapped the test order of 'x' and '\0' so now 'x' is tested first. This
makes changelogs faster since they almost always hit the first branch.
This makes a significant percentage of manifest '\0' chunks slower
because that code path now performs an extra test. Yes, I too can't
believe we're able to measure the impact of an if..elif with simple
string compares. I reckon this code would benefit from being written
in C...

# 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