annotate mercurial/dirstateutils/docket.py @ 47890:3853e6ee160d

dirstatemap: replace `removefile` by an explicit `entry.set_untracked()`

All the other caller goes through `reset_state`, so we can safely have an
explicit method on `DirstateItem` object.
This means that all the logic to preserve the previous state (from p2, merged,
etc) is now properly encapsulated within the DirstateItem. This pave the way to
using different storage for these information.

Differential Revision: https://phab.mercurial-scm.org/D11315

# dirstatedocket.py - docket file for dirstate-v2
#
# Copyright Mercurial Contributors
#
# 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 struct

from ..revlogutils import docket as docket_mod


V2_FORMAT_MARKER = b"dirstate-v2\n"

# Must match the constant of the same name in
# `rust/hg-core/src/dirstate_tree/on_disk.rs`
TREE_METADATA_SIZE = 44

# * 12 bytes: format marker
# * 32 bytes: node ID of the working directory's first parent
# * 32 bytes: node ID of the working directory's second parent
# * 4 bytes: big-endian used size of the data file
# * {TREE_METADATA_SIZE} bytes: tree metadata, parsed separately
# * 1 byte: length of the data file's UUID
# * variable: data file's UUID
#
# Node IDs are null-padded if shorter than 32 bytes.
# A data file shorter than the specified used size is corrupted (truncated)
HEADER = struct.Struct(
    ">{}s32s32sL{}sB".format(len(V2_FORMAT_MARKER), TREE_METADATA_SIZE)
)


class DirstateDocket(object):
    data_filename_pattern = b'dirstate.%s.d'

    def __init__(self, parents, data_size, tree_metadata, uuid):
        self.parents = parents
        self.data_size = data_size
        self.tree_metadata = tree_metadata
        self.uuid = uuid

    @classmethod
    def with_new_uuid(cls, parents, data_size, tree_metadata):
        return cls(parents, data_size, tree_metadata, docket_mod.make_uid())

    @classmethod
    def parse(cls, data, nodeconstants):
        if not data:
            parents = (nodeconstants.nullid, nodeconstants.nullid)
            return cls(parents, 0, b'', None)
        marker, p1, p2, data_size, meta, uuid_size = HEADER.unpack_from(data)
        if marker != V2_FORMAT_MARKER:
            raise ValueError("expected dirstate-v2 marker")
        uuid = data[HEADER.size : HEADER.size + uuid_size]
        p1 = p1[: nodeconstants.nodelen]
        p2 = p2[: nodeconstants.nodelen]
        return cls((p1, p2), data_size, meta, uuid)

    def serialize(self):
        p1, p2 = self.parents
        header = HEADER.pack(
            V2_FORMAT_MARKER,
            p1,
            p2,
            self.data_size,
            self.tree_metadata,
            len(self.uuid),
        )
        return header + self.uuid

    def data_filename(self):
        return self.data_filename_pattern % self.uuid