comparison mercurial/mergestate.py @ 45509:cc5f811b1f15

mergestate: extract a base class to be shared by future memmergestate

This extracts a new base class from `mergestate` and leaves all the
vfs-touching code in `mergestate`.

Differential Revision: https://phab.mercurial-scm.org/D9039

45508:e833ff4dd0ea

ACTION_KEEP_ABSENT = b'ka'
ACTION_EXEC = b'e'
ACTION_CREATED_MERGE = b'cm'


class mergestate(object):
    '''track 3-way merge state of individual files

    The merge state is stored on disk when needed. Two files are used: one with
    an old format (version 1), and one with a new format (version 2). Version 2
    stores a superset of the data in version 1, including new kinds of records

    d: driver-resolved conflict

    The resolve command transitions between 'u' and 'r' for conflicts and
    'pu' and 'pr' for path conflicts.
    '''

    statepathv1 = b'merge/state'
    statepathv2 = b'merge/state2'

    @staticmethod
    def clean(repo):
        """Initialize a brand new merge state, removing any existing state on
        disk."""
        ms = mergestate(repo)
        ms.reset()
        return ms

    @staticmethod
    def read(repo):
        """Initialize the merge state, reading it from disk."""
        ms = mergestate(repo)
        ms._read()
        return ms

    def __init__(self, repo):
        """Initialize the merge state.

        Do not use this directly! Instead call read() or clean()."""

        self._local = node
        self._other = other
        self._labels = labels
        if self.mergedriver:
            self._mdstate = MERGE_DRIVER_STATE_SUCCESS

    def _read(self):
        """Analyse each record content to restore a serialized state from disk

        This function process "record" entry produced by the de-serialization
        of on disk file.
        """
        self._mdstate = MERGE_DRIVER_STATE_SUCCESS
        unsupported = set()
        records = self._readrecords()
        for rtype, record in records:
            if rtype == RECORD_LOCAL:
                self._local = bin(record)
            elif rtype == RECORD_OTHER:
                self._other = bin(record)
            elif rtype == RECORD_MERGE_DRIVER_STATE:
                bits = record.split(b'\0', 1)
                mdstate = bits[1]
                if len(mdstate) != 1 or mdstate not in (
                    MERGE_DRIVER_STATE_UNMARKED,
                    MERGE_DRIVER_STATE_MARKED,
                    MERGE_DRIVER_STATE_SUCCESS,
                ):
                    # the merge driver should be idempotent, so just rerun it
                    mdstate = MERGE_DRIVER_STATE_UNMARKED

                self._readmergedriver = bits[0]
                self._mdstate = mdstate
            elif rtype in (
                RECORD_MERGED,
                RECORD_CHANGEDELETE_CONFLICT,
                RECORD_PATH_CONFLICT,
                RECORD_MERGE_DRIVER_MERGE,
                LEGACY_RECORD_RESOLVED_OTHER,
            ):
                bits = record.split(b'\0')
                # merge entry type MERGE_RECORD_MERGED_OTHER is deprecated
                # and we now store related information in _stateextras, so
                # lets write to _stateextras directly
                if bits[1] == MERGE_RECORD_MERGED_OTHER:
                    self._stateextras[bits[0]][b'filenode-source'] = b'other'
                else:
                    self._state[bits[0]] = bits[1:]
            elif rtype == RECORD_FILE_VALUES:
                filename, rawextras = record.split(b'\0', 1)
                extraparts = rawextras.split(b'\0')
                extras = {}
                i = 0
                while i < len(extraparts):
                    extras[extraparts[i]] = extraparts[i + 1]
                    i += 2

                self._stateextras[filename] = extras
            elif rtype == RECORD_LABELS:
                labels = record.split(b'\0', 2)
                self._labels = [l for l in labels if len(l) > 0]
            elif not rtype.islower():
                unsupported.add(rtype)

        if unsupported:
            raise error.UnsupportedMergeRecords(unsupported)

    def _readrecords(self):
        """Read merge state from disk and return a list of record (TYPE, data)

        We read data from both v1 and v2 files and decide which one to use.

        V1 has been used by version prior to 2.9.1 and contains less data than
        v2. We read both versions and check if no data in v2 contradicts
        v1. If there is not contradiction we can safely assume that both v1
        and v2 were written at the same time and use the extract data in v2. If
        there is contradiction we ignore v2 content as we assume an old version
        of Mercurial has overwritten the mergestate file and left an old v2
        file around.

        returns list of record [(TYPE, data), ...]"""
        v1records = self._readrecordsv1()
        v2records = self._readrecordsv2()
        if self._v1v2match(v1records, v2records):
            return v2records
        else:
            # v1 file is newer than v2 file, use it
            # we have to infer the "other" changeset of the merge
            # we cannot do better than that with v1 of the format
            mctx = self._repo[None].parents()[-1]
            v1records.append((RECORD_OTHER, mctx.hex()))
            # add place holder "other" file node information
            # nobody is using it yet so we do no need to fetch the data
            # if mctx was wrong `mctx[bits[-2]]` may fails.
            for idx, r in enumerate(v1records):
                if r[0] == RECORD_MERGED:
                    bits = r[1].split(b'\0')
                    bits.insert(-2, b'')
                    v1records[idx] = (r[0], b'\0'.join(bits))
            return v1records

    def _v1v2match(self, v1records, v2records):
        oldv2 = set()  # old format version of v2 record
        for rec in v2records:
            if rec[0] == RECORD_LOCAL:
                oldv2.add(rec)
            elif rec[0] == RECORD_MERGED:
                # drop the onode data (not contained in v1)
                oldv2.add((RECORD_MERGED, _droponode(rec[1])))
        for rec in v1records:
            if rec not in oldv2:
                return False
        else:
            return True

    def _readrecordsv1(self):
        """read on disk merge state for version 1 file

        returns list of record [(TYPE, data), ...]

        Note: the "F" data from this file are one entry short
              (no "other file node" entry)
        """
        records = []
        try:
            f = self._repo.vfs(self.statepathv1)
            for i, l in enumerate(f):
                if i == 0:
                    records.append((RECORD_LOCAL, l[:-1]))
                else:
                    records.append((RECORD_MERGED, l[:-1]))
            f.close()
        except IOError as err:
            if err.errno != errno.ENOENT:
                raise
        return records

    def _readrecordsv2(self):
        """read on disk merge state for version 2 file

        This format is a list of arbitrary records of the form:

          [type][length][content]

        `type` is a single character, `length` is a 4 byte integer, and
        `content` is an arbitrary byte sequence of length `length`.

        Mercurial versions prior to 3.7 have a bug where if there are
        unsupported mandatory merge records, attempting to clear out the merge
        state with hg update --clean or similar aborts. The 't' record type
        works around that by writing out what those versions treat as an
        advisory record, but later versions interpret as special: the first
        character is the 'real' record type and everything onwards is the data.

        Returns list of records [(TYPE, data), ...]."""
        records = []
        try:
            f = self._repo.vfs(self.statepathv2)
            data = f.read()
            off = 0
            end = len(data)
            while off < end:
                rtype = data[off : off + 1]
                off += 1
                length = _unpack(b'>I', data[off : (off + 4)])[0]
                off += 4
                record = data[off : (off + length)]
                off += length
                if rtype == RECORD_OVERRIDE:
                    rtype, record = record[0:1], record[1:]
                records.append((rtype, record))
            f.close()
        except IOError as err:
            if err.errno != errno.ENOENT:
                raise
        return records

    @util.propertycache
    def mergedriver(self):
        # protect against the following:
        # - A configures a malicious merge driver in their hgrc, then

        if self._labels is not None:
            labels = b'\0'.join(self._labels)
            records.append((RECORD_LABELS, labels))
        return records

    def _writerecords(self, records):
        """Write current state on disk (both v1 and v2)"""
        self._writerecordsv1(records)
        self._writerecordsv2(records)

    def _writerecordsv1(self, records):
        """Write current state on disk in a version 1 file"""
        f = self._repo.vfs(self.statepathv1, b'wb')
        irecords = iter(records)
        lrecords = next(irecords)
        assert lrecords[0] == RECORD_LOCAL
        f.write(hex(self._local) + b'\n')
        for rtype, data in irecords:
            if rtype == RECORD_MERGED:
                f.write(b'%s\n' % _droponode(data))
        f.close()

    def _writerecordsv2(self, records):
        """Write current state on disk in a version 2 file

        See the docstring for _readrecordsv2 for why we use 't'."""
        # these are the records that all version 2 clients can read
        allowlist = (RECORD_LOCAL, RECORD_OTHER, RECORD_MERGED)
        f = self._repo.vfs(self.statepathv2, b'wb')
        for key, data in records:
            assert len(key) == 1
            if key not in allowlist:
                key, data = RECORD_OVERRIDE, b'%s%s' % (key, data)
            format = b'>sI%is' % len(data)
            f.write(_pack(format, key, len(data), data))
        f.close()

    @staticmethod
    def getlocalkey(path):
        """hash the path of a local file context for storage in the .hg/merge
        directory."""

        return hex(hashutil.sha1(path).digest())

    def _make_backup(self, fctx, localkey):
        self._repo.vfs.write(b'merge/' + localkey, fctx.data())

    def _restore_backup(self, fctx, localkey, flags):
        with self._repo.vfs(b'merge/' + localkey) as f:
            fctx.write(f.read(), flags)

    def add(self, fcl, fco, fca, fd):
        """add a new (potentially?) conflicting file the merge state
        fcl: file context for local,
        fco: file context for remote,

        Meant for use by custom merge drivers."""
        self._results[f] = 0, ACTION_GET


def recordupdates(repo, actions, branchmerge, getfiledata):
    """record merge actions to the dirstate"""
    # remove (must come first)
    for f, args, msg in actions.get(ACTION_REMOVE, []):
        if branchmerge:

45509:cc5f811b1f15

ACTION_KEEP_ABSENT = b'ka'
ACTION_EXEC = b'e'
ACTION_CREATED_MERGE = b'cm'


class _mergestate_base(object):
    '''track 3-way merge state of individual files

    The merge state is stored on disk when needed. Two files are used: one with
    an old format (version 1), and one with a new format (version 2). Version 2
    stores a superset of the data in version 1, including new kinds of records

    d: driver-resolved conflict

    The resolve command transitions between 'u' and 'r' for conflicts and
    'pu' and 'pr' for path conflicts.
    '''

    def __init__(self, repo):
        """Initialize the merge state.

        Do not use this directly! Instead call read() or clean()."""

        self._local = node
        self._other = other
        self._labels = labels
        if self.mergedriver:
            self._mdstate = MERGE_DRIVER_STATE_SUCCESS

    @util.propertycache
    def mergedriver(self):
        # protect against the following:
        # - A configures a malicious merge driver in their hgrc, then

        if self._labels is not None:
            labels = b'\0'.join(self._labels)
            records.append((RECORD_LABELS, labels))
        return records

    @staticmethod
    def getlocalkey(path):
        """hash the path of a local file context for storage in the .hg/merge
        directory."""

        return hex(hashutil.sha1(path).digest())

    def _make_backup(self, fctx, localkey):
        raise NotImplementedError()

    def _restore_backup(self, fctx, localkey, flags):
        raise NotImplementedError()

    def add(self, fcl, fco, fca, fd):
        """add a new (potentially?) conflicting file the merge state
        fcl: file context for local,
        fco: file context for remote,

        Meant for use by custom merge drivers."""
        self._results[f] = 0, ACTION_GET


class mergestate(_mergestate_base):

    statepathv1 = b'merge/state'
    statepathv2 = b'merge/state2'

    @staticmethod
    def clean(repo):
        """Initialize a brand new merge state, removing any existing state on
        disk."""
        ms = mergestate(repo)
        ms.reset()
        return ms

    @staticmethod
    def read(repo):
        """Initialize the merge state, reading it from disk."""
        ms = mergestate(repo)
        ms._read()
        return ms

    def _read(self):
        """Analyse each record content to restore a serialized state from disk

        This function process "record" entry produced by the de-serialization
        of on disk file.
        """
        self._mdstate = MERGE_DRIVER_STATE_SUCCESS
        unsupported = set()
        records = self._readrecords()
        for rtype, record in records:
            if rtype == RECORD_LOCAL:
                self._local = bin(record)
            elif rtype == RECORD_OTHER:
                self._other = bin(record)
            elif rtype == RECORD_MERGE_DRIVER_STATE:
                bits = record.split(b'\0', 1)
                mdstate = bits[1]
                if len(mdstate) != 1 or mdstate not in (
                    MERGE_DRIVER_STATE_UNMARKED,
                    MERGE_DRIVER_STATE_MARKED,
                    MERGE_DRIVER_STATE_SUCCESS,
                ):
                    # the merge driver should be idempotent, so just rerun it
                    mdstate = MERGE_DRIVER_STATE_UNMARKED

                self._readmergedriver = bits[0]
                self._mdstate = mdstate
            elif rtype in (
                RECORD_MERGED,
                RECORD_CHANGEDELETE_CONFLICT,
                RECORD_PATH_CONFLICT,
                RECORD_MERGE_DRIVER_MERGE,
                LEGACY_RECORD_RESOLVED_OTHER,
            ):
                bits = record.split(b'\0')
                # merge entry type MERGE_RECORD_MERGED_OTHER is deprecated
                # and we now store related information in _stateextras, so
                # lets write to _stateextras directly
                if bits[1] == MERGE_RECORD_MERGED_OTHER:
                    self._stateextras[bits[0]][b'filenode-source'] = b'other'
                else:
                    self._state[bits[0]] = bits[1:]
            elif rtype == RECORD_FILE_VALUES:
                filename, rawextras = record.split(b'\0', 1)
                extraparts = rawextras.split(b'\0')
                extras = {}
                i = 0
                while i < len(extraparts):
                    extras[extraparts[i]] = extraparts[i + 1]
                    i += 2

                self._stateextras[filename] = extras
            elif rtype == RECORD_LABELS:
                labels = record.split(b'\0', 2)
                self._labels = [l for l in labels if len(l) > 0]
            elif not rtype.islower():
                unsupported.add(rtype)

        if unsupported:
            raise error.UnsupportedMergeRecords(unsupported)

    def _readrecords(self):
        """Read merge state from disk and return a list of record (TYPE, data)

        We read data from both v1 and v2 files and decide which one to use.

        V1 has been used by version prior to 2.9.1 and contains less data than
        v2. We read both versions and check if no data in v2 contradicts
        v1. If there is not contradiction we can safely assume that both v1
        and v2 were written at the same time and use the extract data in v2. If
        there is contradiction we ignore v2 content as we assume an old version
        of Mercurial has overwritten the mergestate file and left an old v2
        file around.

        returns list of record [(TYPE, data), ...]"""
        v1records = self._readrecordsv1()
        v2records = self._readrecordsv2()
        if self._v1v2match(v1records, v2records):
            return v2records
        else:
            # v1 file is newer than v2 file, use it
            # we have to infer the "other" changeset of the merge
            # we cannot do better than that with v1 of the format
            mctx = self._repo[None].parents()[-1]
            v1records.append((RECORD_OTHER, mctx.hex()))
            # add place holder "other" file node information
            # nobody is using it yet so we do no need to fetch the data
            # if mctx was wrong `mctx[bits[-2]]` may fails.
            for idx, r in enumerate(v1records):
                if r[0] == RECORD_MERGED:
                    bits = r[1].split(b'\0')
                    bits.insert(-2, b'')
                    v1records[idx] = (r[0], b'\0'.join(bits))
            return v1records

    def _v1v2match(self, v1records, v2records):
        oldv2 = set()  # old format version of v2 record
        for rec in v2records:
            if rec[0] == RECORD_LOCAL:
                oldv2.add(rec)
            elif rec[0] == RECORD_MERGED:
                # drop the onode data (not contained in v1)
                oldv2.add((RECORD_MERGED, _droponode(rec[1])))
        for rec in v1records:
            if rec not in oldv2:
                return False
        else:
            return True

    def _readrecordsv1(self):
        """read on disk merge state for version 1 file

        returns list of record [(TYPE, data), ...]

        Note: the "F" data from this file are one entry short
              (no "other file node" entry)
        """
        records = []
        try:
            f = self._repo.vfs(self.statepathv1)
            for i, l in enumerate(f):
                if i == 0:
                    records.append((RECORD_LOCAL, l[:-1]))
                else:
                    records.append((RECORD_MERGED, l[:-1]))
            f.close()
        except IOError as err:
            if err.errno != errno.ENOENT:
                raise
        return records

    def _readrecordsv2(self):
        """read on disk merge state for version 2 file

        This format is a list of arbitrary records of the form:

          [type][length][content]

        `type` is a single character, `length` is a 4 byte integer, and
        `content` is an arbitrary byte sequence of length `length`.

        Mercurial versions prior to 3.7 have a bug where if there are
        unsupported mandatory merge records, attempting to clear out the merge
        state with hg update --clean or similar aborts. The 't' record type
        works around that by writing out what those versions treat as an
        advisory record, but later versions interpret as special: the first
        character is the 'real' record type and everything onwards is the data.

        Returns list of records [(TYPE, data), ...]."""
        records = []
        try:
            f = self._repo.vfs(self.statepathv2)
            data = f.read()
            off = 0
            end = len(data)
            while off < end:
                rtype = data[off : off + 1]
                off += 1
                length = _unpack(b'>I', data[off : (off + 4)])[0]
                off += 4
                record = data[off : (off + length)]
                off += length
                if rtype == RECORD_OVERRIDE:
                    rtype, record = record[0:1], record[1:]
                records.append((rtype, record))
            f.close()
        except IOError as err:
            if err.errno != errno.ENOENT:
                raise
        return records

    def _writerecords(self, records):
        """Write current state on disk (both v1 and v2)"""
        self._writerecordsv1(records)
        self._writerecordsv2(records)

    def _writerecordsv1(self, records):
        """Write current state on disk in a version 1 file"""
        f = self._repo.vfs(self.statepathv1, b'wb')
        irecords = iter(records)
        lrecords = next(irecords)
        assert lrecords[0] == RECORD_LOCAL
        f.write(hex(self._local) + b'\n')
        for rtype, data in irecords:
            if rtype == RECORD_MERGED:
                f.write(b'%s\n' % _droponode(data))
        f.close()

    def _writerecordsv2(self, records):
        """Write current state on disk in a version 2 file

        See the docstring for _readrecordsv2 for why we use 't'."""
        # these are the records that all version 2 clients can read
        allowlist = (RECORD_LOCAL, RECORD_OTHER, RECORD_MERGED)
        f = self._repo.vfs(self.statepathv2, b'wb')
        for key, data in records:
            assert len(key) == 1
            if key not in allowlist:
                key, data = RECORD_OVERRIDE, b'%s%s' % (key, data)
            format = b'>sI%is' % len(data)
            f.write(_pack(format, key, len(data), data))
        f.close()

    def _make_backup(self, fctx, localkey):
        self._repo.vfs.write(b'merge/' + localkey, fctx.data())

    def _restore_backup(self, fctx, localkey, flags):
        with self._repo.vfs(b'merge/' + localkey) as f:
            fctx.write(f.read(), flags)

    def reset(self):
        shutil.rmtree(self._repo.vfs.join(b'merge'), True)


def recordupdates(repo, actions, branchmerge, getfiledata):
    """record merge actions to the dirstate"""
    # remove (must come first)
    for f, args, msg in actions.get(ACTION_REMOVE, []):
        if branchmerge: