Mercurial > hg
view mercurial/revlogutils/sidedata.py @ 43142:beed7ce61681
sidedatacopies: write copies information in sidedata when applicable
If the format of the repository indicate it stores copies information into
changeset's sidedata, then we actually write that information into sidedata at
commit time. It will be put to use in later changesets.
Currently, we store all field unconditionally, but that is likely to change in
the future for the sake of efficiency.
Differential Revision: https://phab.mercurial-scm.org/D6950
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
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date | Sun, 06 Oct 2019 23:36:51 -0400 |
parents | 687b865b95ad |
children | 9f70512ae2cf |
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# 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, withing the revision rawtext. They are inserted, 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 enought to experiment with the concept. """ from __future__ import absolute_import import hashlib import struct from .. import error ## 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 # internal format constant SIDEDATA_HEADER = struct.Struct(r'>H') SIDEDATA_ENTRY = struct.Struct(r'>HL20s') def sidedatawriteprocessor(rl, text, sidedata): sidedata = list(sidedata.items()) sidedata.sort() rawtext = [SIDEDATA_HEADER.pack(len(sidedata))] for key, value in sidedata: digest = hashlib.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 = hashlib.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, )