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# revlogdeltas.py - constant used for revlog logic.
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#
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# Copyright 2005-2007 Olivia Mackall <olivia@selenic.com>
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# Copyright 2018 Octobus <contact@octobus.net>
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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"""Helper class to compute deltas stored inside revlogs"""
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from __future__ import absolute_import
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import struct
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from ..interfaces import repository
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### Internal utily constants
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KIND_CHANGELOG = 1001 # over 256 to not be comparable with a bytes
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KIND_MANIFESTLOG = 1002
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KIND_FILELOG = 1003
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KIND_OTHER = 1004
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ALL_KINDS = {
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KIND_CHANGELOG,
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KIND_MANIFESTLOG,
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KIND_FILELOG,
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KIND_OTHER,
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}
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### main revlog header
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INDEX_HEADER = struct.Struct(b">I")
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## revlog version
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REVLOGV0 = 0
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REVLOGV1 = 1
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# Dummy value until file format is finalized.
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REVLOGV2 = 0xDEAD
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## global revlog header flags
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# Shared across v1 and v2.
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FLAG_INLINE_DATA = 1 << 16
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# Only used by v1, implied by v2.
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FLAG_GENERALDELTA = 1 << 17
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REVLOG_DEFAULT_FLAGS = FLAG_INLINE_DATA
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REVLOG_DEFAULT_FORMAT = REVLOGV1
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REVLOG_DEFAULT_VERSION = REVLOG_DEFAULT_FORMAT | REVLOG_DEFAULT_FLAGS
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REVLOGV0_FLAGS = 0
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REVLOGV1_FLAGS = FLAG_INLINE_DATA | FLAG_GENERALDELTA
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REVLOGV2_FLAGS = FLAG_INLINE_DATA
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### individual entry
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## index v0:
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# 4 bytes: offset
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# 4 bytes: compressed length
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# 4 bytes: base rev
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# 4 bytes: link rev
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# 20 bytes: parent 1 nodeid
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# 20 bytes: parent 2 nodeid
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# 20 bytes: nodeid
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INDEX_ENTRY_V0 = struct.Struct(b">4l20s20s20s")
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## index v1
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# 6 bytes: offset
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# 2 bytes: flags
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# 4 bytes: compressed length
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# 4 bytes: uncompressed length
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# 4 bytes: base rev
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# 4 bytes: link rev
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# 4 bytes: parent 1 rev
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# 4 bytes: parent 2 rev
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# 32 bytes: nodeid
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INDEX_ENTRY_V1 = struct.Struct(b">Qiiiiii20s12x")
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assert INDEX_ENTRY_V1.size == 32 * 2
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# 6 bytes: offset
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# 2 bytes: flags
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# 4 bytes: compressed length
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# 4 bytes: uncompressed length
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# 4 bytes: base rev
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# 4 bytes: link rev
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# 4 bytes: parent 1 rev
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# 4 bytes: parent 2 rev
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# 32 bytes: nodeid
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# 8 bytes: sidedata offset
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# 4 bytes: sidedata compressed length
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# 1 bytes: compression mode (2 lower bit are data_compression_mode)
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# 19 bytes: Padding to align to 96 bytes (see RevlogV2Plan wiki page)
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INDEX_ENTRY_V2 = struct.Struct(b">Qiiiiii20s12xQiB19x")
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assert INDEX_ENTRY_V2.size == 32 * 3, INDEX_ENTRY_V2.size
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# revlog index flags
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# For historical reasons, revlog's internal flags were exposed via the
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# wire protocol and are even exposed in parts of the storage APIs.
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# revision has censor metadata, must be verified
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REVIDX_ISCENSORED = repository.REVISION_FLAG_CENSORED
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# revision hash does not match data (narrowhg)
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REVIDX_ELLIPSIS = repository.REVISION_FLAG_ELLIPSIS
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# revision data is stored externally
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REVIDX_EXTSTORED = repository.REVISION_FLAG_EXTSTORED
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# revision changes files in a way that could affect copy tracing.
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REVIDX_HASCOPIESINFO = repository.REVISION_FLAG_HASCOPIESINFO
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REVIDX_DEFAULT_FLAGS = 0
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# stable order in which flags need to be processed and their processors applied
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REVIDX_FLAGS_ORDER = [
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REVIDX_ISCENSORED,
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REVIDX_ELLIPSIS,
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REVIDX_EXTSTORED,
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REVIDX_HASCOPIESINFO,
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]
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# bitmark for flags that could cause rawdata content change
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REVIDX_RAWTEXT_CHANGING_FLAGS = REVIDX_ISCENSORED | REVIDX_EXTSTORED
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## chunk compression mode constants:
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# These constants are used in revlog version >=2 to denote the compression used
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# for a chunk.
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# Chunk use a compression mode stored "inline" at the start of the chunk
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# itself. This is the mode always used for revlog version "0" and "1"
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COMP_MODE_INLINE = 2
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SUPPORTED_FLAGS = {
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REVLOGV0: REVLOGV0_FLAGS,
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REVLOGV1: REVLOGV1_FLAGS,
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REVLOGV2: REVLOGV2_FLAGS,
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}
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_no = lambda flags: False
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_yes = lambda flags: True
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def _from_flag(flag):
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return lambda flags: bool(flags & flag)
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FEATURES_BY_VERSION = {
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REVLOGV0: {
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b'inline': _no,
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b'generaldelta': _no,
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b'sidedata': False,
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b'docket': False,
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},
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REVLOGV1: {
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b'inline': _from_flag(FLAG_INLINE_DATA),
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b'generaldelta': _from_flag(FLAG_GENERALDELTA),
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b'sidedata': False,
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b'docket': False,
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},
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REVLOGV2: {
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# The point of inline-revlog is to reduce the number of files used in
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# the store. Using a docket defeat this purpose. So we needs other
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# means to reduce the number of files for revlogv2.
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b'inline': _no,
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b'generaldelta': _yes,
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b'sidedata': True,
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b'docket': True,
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},
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}
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SPARSE_REVLOG_MAX_CHAIN_LENGTH = 1000
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