Mercurial > hg
view mercurial/revlogutils/constants.py @ 47371:298d4400ea68
index: use an explicit constant for INDEX_HEADER format and use it for docket
This avoid leaking python-3.6 compatibility details too much.
Differential Revision: https://phab.mercurial-scm.org/D10831
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
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date | Thu, 03 Jun 2021 16:12:03 +0200 |
parents | 25ce16bf724b |
children | 7a0ec25d5836 |
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# revlogdeltas.py - constant used for revlog logic. # # Copyright 2005-2007 Olivia Mackall <olivia@selenic.com> # Copyright 2018 Octobus <contact@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. """Helper class to compute deltas stored inside revlogs""" from __future__ import absolute_import import struct from ..interfaces import repository ### Internal utily constants KIND_CHANGELOG = 1001 # over 256 to not be comparable with a bytes KIND_MANIFESTLOG = 1002 KIND_FILELOG = 1003 KIND_OTHER = 1004 ALL_KINDS = { KIND_CHANGELOG, KIND_MANIFESTLOG, KIND_FILELOG, KIND_OTHER, } ### main revlog header # We cannot rely on Struct.format is inconsistent for python <=3.6 versus above INDEX_HEADER_FMT = b">I" INDEX_HEADER = struct.Struct(INDEX_HEADER_FMT) ## revlog version REVLOGV0 = 0 REVLOGV1 = 1 # Dummy value until file format is finalized. REVLOGV2 = 0xDEAD # Dummy value until file format is finalized. CHANGELOGV2 = 0xD34D ## global revlog header flags # Shared across v1 and v2. FLAG_INLINE_DATA = 1 << 16 # Only used by v1, implied by v2. FLAG_GENERALDELTA = 1 << 17 REVLOG_DEFAULT_FLAGS = FLAG_INLINE_DATA REVLOG_DEFAULT_FORMAT = REVLOGV1 REVLOG_DEFAULT_VERSION = REVLOG_DEFAULT_FORMAT | REVLOG_DEFAULT_FLAGS REVLOGV0_FLAGS = 0 REVLOGV1_FLAGS = FLAG_INLINE_DATA | FLAG_GENERALDELTA REVLOGV2_FLAGS = FLAG_INLINE_DATA CHANGELOGV2_FLAGS = 0 ### individual entry ## index v0: # 4 bytes: offset # 4 bytes: compressed length # 4 bytes: base rev # 4 bytes: link rev # 20 bytes: parent 1 nodeid # 20 bytes: parent 2 nodeid # 20 bytes: nodeid INDEX_ENTRY_V0 = struct.Struct(b">4l20s20s20s") ## index v1 # 6 bytes: offset # 2 bytes: flags # 4 bytes: compressed length # 4 bytes: uncompressed length # 4 bytes: base rev # 4 bytes: link rev # 4 bytes: parent 1 rev # 4 bytes: parent 2 rev # 32 bytes: nodeid INDEX_ENTRY_V1 = struct.Struct(b">Qiiiiii20s12x") assert INDEX_ENTRY_V1.size == 32 * 2 # 6 bytes: offset # 2 bytes: flags # 4 bytes: compressed length # 4 bytes: uncompressed length # 4 bytes: base rev # 4 bytes: link rev # 4 bytes: parent 1 rev # 4 bytes: parent 2 rev # 32 bytes: nodeid # 8 bytes: sidedata offset # 4 bytes: sidedata compressed length # 1 bytes: compression mode (2 lower bit are data_compression_mode) # 19 bytes: Padding to align to 96 bytes (see RevlogV2Plan wiki page) INDEX_ENTRY_V2 = struct.Struct(b">Qiiiiii20s12xQiB19x") assert INDEX_ENTRY_V2.size == 32 * 3, INDEX_ENTRY_V2.size # 6 bytes: offset # 2 bytes: flags # 4 bytes: compressed length # 4 bytes: uncompressed length # 4 bytes: parent 1 rev # 4 bytes: parent 2 rev # 32 bytes: nodeid # 8 bytes: sidedata offset # 4 bytes: sidedata compressed length # 1 bytes: compression mode (2 lower bit are data_compression_mode) # 27 bytes: Padding to align to 96 bytes (see RevlogV2Plan wiki page) INDEX_ENTRY_CL_V2 = struct.Struct(b">Qiiii20s12xQiB27x") assert INDEX_ENTRY_CL_V2.size == 32 * 3, INDEX_ENTRY_V2.size # revlog index flags # For historical reasons, revlog's internal flags were exposed via the # wire protocol and are even exposed in parts of the storage APIs. # revision has censor metadata, must be verified REVIDX_ISCENSORED = repository.REVISION_FLAG_CENSORED # revision hash does not match data (narrowhg) REVIDX_ELLIPSIS = repository.REVISION_FLAG_ELLIPSIS # revision data is stored externally REVIDX_EXTSTORED = repository.REVISION_FLAG_EXTSTORED # revision changes files in a way that could affect copy tracing. REVIDX_HASCOPIESINFO = repository.REVISION_FLAG_HASCOPIESINFO REVIDX_DEFAULT_FLAGS = 0 # stable order in which flags need to be processed and their processors applied REVIDX_FLAGS_ORDER = [ REVIDX_ISCENSORED, REVIDX_ELLIPSIS, REVIDX_EXTSTORED, REVIDX_HASCOPIESINFO, ] # bitmark for flags that could cause rawdata content change REVIDX_RAWTEXT_CHANGING_FLAGS = REVIDX_ISCENSORED | REVIDX_EXTSTORED ## chunk compression mode constants: # These constants are used in revlog version >=2 to denote the compression used # for a chunk. # Chunk use no compression, the data stored on disk can be directly use as # chunk value. Without any header information prefixed. COMP_MODE_PLAIN = 0 # Chunk use the "default compression" for the revlog (usually defined in the # revlog docket). A header is still used. # # XXX: keeping a header is probably not useful and we should probably drop it. # # XXX: The value of allow mixed type of compression in the revlog is unclear # and we should consider making PLAIN/DEFAULT the only available mode for # revlog v2, disallowing INLINE mode. COMP_MODE_DEFAULT = 1 # Chunk use a compression mode stored "inline" at the start of the chunk # itself. This is the mode always used for revlog version "0" and "1" COMP_MODE_INLINE = 2 SUPPORTED_FLAGS = { REVLOGV0: REVLOGV0_FLAGS, REVLOGV1: REVLOGV1_FLAGS, REVLOGV2: REVLOGV2_FLAGS, CHANGELOGV2: CHANGELOGV2_FLAGS, } _no = lambda flags: False _yes = lambda flags: True def _from_flag(flag): return lambda flags: bool(flags & flag) FEATURES_BY_VERSION = { REVLOGV0: { b'inline': _no, b'generaldelta': _no, b'sidedata': False, b'docket': False, }, REVLOGV1: { b'inline': _from_flag(FLAG_INLINE_DATA), b'generaldelta': _from_flag(FLAG_GENERALDELTA), b'sidedata': False, b'docket': False, }, REVLOGV2: { # The point of inline-revlog is to reduce the number of files used in # the store. Using a docket defeat this purpose. So we needs other # means to reduce the number of files for revlogv2. b'inline': _no, b'generaldelta': _yes, b'sidedata': True, b'docket': True, }, CHANGELOGV2: { b'inline': _no, # General delta is useless for changelog since we don't do any delta b'generaldelta': _no, b'sidedata': True, b'docket': True, }, } SPARSE_REVLOG_MAX_CHAIN_LENGTH = 1000