mercurial/revlogutils/constants.py
author Gregory Szorc <gregory.szorc@gmail.com>
Wed, 03 Oct 2018 12:57:01 -0700
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parent 39506 b66ea3fc3a86
child 41202 e7a2cc84dbc0
permissions -rw-r--r--
repository: define and use revision flag constants Revlogs have a per-revision 2 byte field holding integer flags that define how revision data should be interpreted. For historical reasons, these integer values are sent verbatim on the wire protocol as part of changegroup data. From a semantic standpoint, the flags that go out over the wire are different from the flags stored internally by revlogs. Failure to establish this semantic distinction creates unwanted strong coupling between revlog's internals and the wire protocol. This commit establishes new constants on the repository module that define the revision flags used by the wire protocol (and by some internal storage APIs, sadly). The changegroups internals documentation has been updated to document them explicitly. Various references throughout the repo now use the repository constants instead of the revlog constants. This is done to make it clear that we're operating on generic revision data and this isn't tied to revlogs. Differential Revision: https://phab.mercurial-scm.org/D4860
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# revlogdeltas.py - constant used for revlog logic
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#
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# Copyright 2005-2007 Matt Mackall <mpm@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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from .. import (
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    repository,
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    util,
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)
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# revlog header flags
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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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# Reminder: change the bounds check in revlog.__init__ when this is changed.
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REVLOGV2 = 0xDEAD
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FLAG_INLINE_DATA = (1 << 16)
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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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REVLOGV1_FLAGS = FLAG_INLINE_DATA | FLAG_GENERALDELTA
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REVLOGV2_FLAGS = REVLOGV1_FLAGS
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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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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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]
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REVIDX_KNOWN_FLAGS = util.bitsfrom(REVIDX_FLAGS_ORDER)
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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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SPARSE_REVLOG_MAX_CHAIN_LENGTH = 1000
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