[PATCH 2 of 5 STABLE] merge: new format for the state file

[Olle]

On Wed, Feb 26, 2014 at 11:58 PM, <pierre-yves.david at ens-lyon.org> wrote:

> # HG changeset patch
> # User Pierre-Yves David <pierre-yves.david at fb.com>
> # Date 1393382226 28800
> #      Tue Feb 25 18:37:06 2014 -0800
> # Branch stable
> # Node ID d229b5d2096e7fdcc362fe22ff049ae257365c51
> # Parent  a0c9e2941511a01624a0a75c000190f4ce3ed467
> merge: new format for the state file
>
> This new format will allow use to address common bugs with doing special
> merge
> (graft, backout, rebase...) and record user choice during conflict
> resolution.
>
> The format is open so we can add more record for future usage.
>
> I'm keeping hexified version of node in this file to help human willing to
> debug
> it by hand. I do not expect the overhead or oversize to be an issue.
>
> diff --git a/mercurial/merge.py b/mercurial/merge.py
> --- a/mercurial/merge.py
> +++ b/mercurial/merge.py
> @@ -3,20 +3,40 @@
>  # Copyright 2006, 2007 Matt Mackall <mpm at 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.
>
> +import struct
> +
>  from node import nullid, nullrev, hex, bin
>  from i18n import _
>  from mercurial import obsolete
>  import error, util, filemerge, copies, subrepo, worker, dicthelpers
>  import errno, os, shutil
>
> +_pack = struct.pack
> +_unpack = struct.unpack
> +
>  class mergestate(object):
> -    '''track 3-way merge state of individual files'''
> -    statepath = "merge/state"
> +    '''track 3-way merge state of individual files
>
> +    current format is a list of arbitrary record of the form:
> +
> +        [type][length][content]
> +
> +    Type is a single character, length is a 4 bytes integer, content is an
> +    arbitrary suites of bytes of lenght `length`.
>
length

> +
> +    Type should be a letter. Capital letter are mandatory record,
> Mercurial
> +    should abort if they are unknown. lower case record can be safely
> ignored.
> +
> +    Currently known record:
> +
> +    L: the node of the "local" part of the merge (hexified version)
> +    F: a file to be merged entry
> +    '''
> +    statepath = "merge/state2"
>      def __init__(self, repo):
>          self._repo = repo
>          self._dirty = False
>          self._read()
>      def reset(self, node=None):
> @@ -27,29 +47,52 @@ class mergestate(object):
>          self._dirty = False
>      def _read(self):
>          self._state = {}
>          try:
>              f = self._repo.opener(self.statepath)
> -            for i, l in enumerate(f):
> -                if i == 0:
> -                    self._local = bin(l[:-1])
> -                else:
> -                    bits = l[:-1].split("\0")
> +            for rtype, record in self._readrecords(f):
> +                if rtype == 'L':
> +                    self._local = bin(record)
> +                elif rtype == "F":
> +                    bits = record.split("\0")
>                      self._state[bits[0]] = bits[1:]
> +                elif not rtype.islower():
> +                    raise util.Abort(_('unsupported merge state record:'
> +                                       % rtype))
>              f.close()
>          except IOError, err:
>              if err.errno != errno.ENOENT:
>                  raise
>          self._dirty = False
> +    def _readrecords(self, f):
> +        data = f.read()
> +        off = 0
> +        end = len(data)
> +        while off < end:
> +            rtype = data[off]
> +            off += 1
> +            lenght = _unpack('>I', data[off:(off + 4)])[0]
>
length

> +            off += 4
> +            record = data[off:(off + lenght)]
>
length

> +            off += lenght
>
length

> +            yield rtype, record
> +
>      def commit(self):
>          if self._dirty:
> +            records = []
> +            records.append(("L", hex(self._local)))
> +            for d, v in self._state.iteritems():
> +                records.append(("F", "\0".join([d] + v)))
> +            self._writerecords(records)
> +            self._dirty = False
> +    def _writerecords(self, records):
>              f = self._repo.opener(self.statepath, "w")
> -            f.write(hex(self._local) + "\n")
> -            for d, v in self._state.iteritems():
> -                f.write("\0".join([d] + v) + "\n")
> +            for key, data in records:
> +                assert len(key) == 1
> +                format = ">sI%is" % len(data)
> +                f.write(_pack(format, key, len(data), data))
>              f.close()
> -            self._dirty = False
>      def add(self, fcl, fco, fca, fd):
>          hash = util.sha1(fcl.path()).hexdigest()
>          self._repo.opener.write("merge/" + hash, fcl.data())
>          self._state[fd] = ['u', hash, fcl.path(), fca.path(),
>                             hex(fca.filenode()), fco.path(), fcl.flags()]
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>



-- 
Olle
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