|
|
# sidedata.py - Logic around store extra data alongside revlog revisions
|
|
|
#
|
|
|
# Copyright 2019 Pierre-Yves David <pierre-yves.david@octobus.net)
|
|
|
#
|
|
|
# This software may be used and distributed according to the terms of the
|
|
|
# GNU General Public License version 2 or any later version.
|
|
|
"""core code for "sidedata" support
|
|
|
|
|
|
The "sidedata" are stored alongside the revision without actually being part of
|
|
|
its content and not affecting its hash. It's main use cases is to cache
|
|
|
important information related to a changesets.
|
|
|
|
|
|
The current implementation is experimental and subject to changes. Do not rely
|
|
|
on it in production.
|
|
|
|
|
|
Sidedata are stored in the revlog itself, within the revision rawtext. They
|
|
|
are inserted and removed from it using the flagprocessors mechanism. The following
|
|
|
format is currently used::
|
|
|
|
|
|
initial header:
|
|
|
<number of sidedata; 2 bytes>
|
|
|
sidedata (repeated N times):
|
|
|
<sidedata-key; 2 bytes>
|
|
|
<sidedata-entry-length: 4 bytes>
|
|
|
<sidedata-content-sha1-digest: 20 bytes>
|
|
|
<sidedata-content; X bytes>
|
|
|
normal raw text:
|
|
|
<all bytes remaining in the rawtext>
|
|
|
|
|
|
This is a simple and effective format. It should be enough to experiment with
|
|
|
the concept.
|
|
|
"""
|
|
|
|
|
|
from __future__ import absolute_import
|
|
|
|
|
|
import struct
|
|
|
|
|
|
from .. import error
|
|
|
from ..utils import hashutil
|
|
|
|
|
|
## sidedata type constant
|
|
|
# reserve a block for testing purposes.
|
|
|
SD_TEST1 = 1
|
|
|
SD_TEST2 = 2
|
|
|
SD_TEST3 = 3
|
|
|
SD_TEST4 = 4
|
|
|
SD_TEST5 = 5
|
|
|
SD_TEST6 = 6
|
|
|
SD_TEST7 = 7
|
|
|
|
|
|
# key to store copies related information
|
|
|
SD_P1COPIES = 8
|
|
|
SD_P2COPIES = 9
|
|
|
SD_FILESADDED = 10
|
|
|
SD_FILESREMOVED = 11
|
|
|
SD_FILES = 12
|
|
|
|
|
|
# internal format constant
|
|
|
SIDEDATA_HEADER = struct.Struct('>H')
|
|
|
SIDEDATA_ENTRY = struct.Struct('>HL20s')
|
|
|
|
|
|
|
|
|
def sidedatawriteprocessor(rl, text, sidedata):
|
|
|
sidedata = list(sidedata.items())
|
|
|
sidedata.sort()
|
|
|
rawtext = [SIDEDATA_HEADER.pack(len(sidedata))]
|
|
|
for key, value in sidedata:
|
|
|
digest = hashutil.sha1(value).digest()
|
|
|
rawtext.append(SIDEDATA_ENTRY.pack(key, len(value), digest))
|
|
|
for key, value in sidedata:
|
|
|
rawtext.append(value)
|
|
|
rawtext.append(bytes(text))
|
|
|
return b''.join(rawtext), False
|
|
|
|
|
|
|
|
|
def sidedatareadprocessor(rl, text):
|
|
|
sidedata = {}
|
|
|
offset = 0
|
|
|
(nbentry,) = SIDEDATA_HEADER.unpack(text[: SIDEDATA_HEADER.size])
|
|
|
offset += SIDEDATA_HEADER.size
|
|
|
dataoffset = SIDEDATA_HEADER.size + (SIDEDATA_ENTRY.size * nbentry)
|
|
|
for i in range(nbentry):
|
|
|
nextoffset = offset + SIDEDATA_ENTRY.size
|
|
|
key, size, storeddigest = SIDEDATA_ENTRY.unpack(text[offset:nextoffset])
|
|
|
offset = nextoffset
|
|
|
# read the data associated with that entry
|
|
|
nextdataoffset = dataoffset + size
|
|
|
entrytext = text[dataoffset:nextdataoffset]
|
|
|
readdigest = hashutil.sha1(entrytext).digest()
|
|
|
if storeddigest != readdigest:
|
|
|
raise error.SidedataHashError(key, storeddigest, readdigest)
|
|
|
sidedata[key] = entrytext
|
|
|
dataoffset = nextdataoffset
|
|
|
text = text[dataoffset:]
|
|
|
return text, True, sidedata
|
|
|
|
|
|
|
|
|
def sidedatarawprocessor(rl, text):
|
|
|
# side data modifies rawtext and prevent rawtext hash validation
|
|
|
return False
|
|
|
|
|
|
|
|
|
processors = (
|
|
|
sidedatareadprocessor,
|
|
|
sidedatawriteprocessor,
|
|
|
sidedatarawprocessor,
|
|
|
)
|
|
|
|
