mercurial/requirements.py

stream-clone: stop getting the file size of all file in v3

The point of v3 is to do less work in the locked section. It was currently not
the case.


This significantly boost performance. The following number comes from a large
private repository using perf::stream-locked-section:

base-line:   35.03 seconds
this-change: 24.50 seconds (-30%)

# requirements.py - objects and functions related to repository requirements
#
# Copyright 2005-2007 Olivia Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.


# obsolete experimental requirements:
#  - manifestv2: An experimental new manifest format that allowed
#    for stem compression of long paths. Experiment ended up not
#    being successful (repository sizes went up due to worse delta
#    chains), and the code was deleted in 4.6.

GENERALDELTA_REQUIREMENT = b'generaldelta'
DOTENCODE_REQUIREMENT = b'dotencode'
STORE_REQUIREMENT = b'store'
FNCACHE_REQUIREMENT = b'fncache'

DIRSTATE_TRACKED_HINT_V1 = b'dirstate-tracked-key-v1'
DIRSTATE_V2_REQUIREMENT = b'dirstate-v2'

# When narrowing is finalized and no longer subject to format changes,
# we should move this to just "narrow" or similar.
NARROW_REQUIREMENT = b'narrowhg-experimental'

# Enables sparse working directory usage
SPARSE_REQUIREMENT = b'exp-sparse'

# Enables the internal phase which is used to hide changesets instead
# of stripping them
INTERNAL_PHASE_REQUIREMENT = b'internal-phase-2'

# Enables the internal phase which is used to hide changesets instead
# of stripping them
ARCHIVED_PHASE_REQUIREMENT = b'exp-archived-phase'

# Stores manifest in Tree structure
TREEMANIFEST_REQUIREMENT = b'treemanifest'

REVLOGV1_REQUIREMENT = b'revlogv1'

# allow using ZSTD as compression engine for revlog content
REVLOG_COMPRESSION_ZSTD = b'revlog-compression-zstd'

# Increment the sub-version when the revlog v2 format changes to lock out old
# clients.
CHANGELOGV2_REQUIREMENT = b'exp-changelog-v2'

# Increment the sub-version when the revlog v2 format changes to lock out old
# clients.
REVLOGV2_REQUIREMENT = b'exp-revlogv2.2'

# A repository with the sparserevlog feature will have delta chains that
# can spread over a larger span. Sparse reading cuts these large spans into
# pieces, so that each piece isn't too big.
# Without the sparserevlog capability, reading from the repository could use
# huge amounts of memory, because the whole span would be read at once,
# including all the intermediate revisions that aren't pertinent for the chain.
# This is why once a repository has enabled sparse-read, it becomes required.
SPARSEREVLOG_REQUIREMENT = b'sparserevlog'

# A repository with the the copies-sidedata-changeset requirement will store
# copies related information in changeset's sidedata.
COPIESSDC_REQUIREMENT = b'exp-copies-sidedata-changeset'

# The repository use persistent nodemap for the changelog and the manifest.
NODEMAP_REQUIREMENT = b'persistent-nodemap'

# Denotes that the current repository is a share
SHARED_REQUIREMENT = b'shared'

# Denotes that current repository is a share and the shared source path is
# relative to the current repository root path
RELATIVE_SHARED_REQUIREMENT = b'relshared'

# A repository with share implemented safely. The repository has different
# store and working copy requirements i.e. both `.hg/requires` and
# `.hg/store/requires` are present.
SHARESAFE_REQUIREMENT = b'share-safe'

# Bookmarks must be stored in the `store` part of the repository and will be
# share accross shares
BOOKMARKS_IN_STORE_REQUIREMENT = b'bookmarksinstore'

# List of requirements which are working directory specific
# These requirements cannot be shared between repositories if they
# share the same store
# * sparse is a working directory specific functionality and hence working
#   directory specific requirement
# * SHARED_REQUIREMENT and RELATIVE_SHARED_REQUIREMENT are requirements which
#   represents that the current working copy/repository shares store of another
#   repo. Hence both of them should be stored in working copy
# * SHARESAFE_REQUIREMENT needs to be stored in working dir to mark that rest of
#   the requirements are stored in store's requires
# * DIRSTATE_V2_REQUIREMENT affects .hg/dirstate, of which there is one per
#   working directory.
WORKING_DIR_REQUIREMENTS = {
    SPARSE_REQUIREMENT,
    SHARED_REQUIREMENT,
    RELATIVE_SHARED_REQUIREMENT,
    SHARESAFE_REQUIREMENT,
    DIRSTATE_TRACKED_HINT_V1,
    DIRSTATE_V2_REQUIREMENT,
}

# List of requirement that impact "stream-clone" (and hardlink clone) and
# cannot be changed in such cases.
#
# requirements not in this list are safe to be altered during stream-clone.
#
# note: the list is currently inherited from previous code and miss some relevant requirement while containing some irrelevant ones.
STREAM_FIXED_REQUIREMENTS = {
    ARCHIVED_PHASE_REQUIREMENT,
    BOOKMARKS_IN_STORE_REQUIREMENT,
    CHANGELOGV2_REQUIREMENT,
    COPIESSDC_REQUIREMENT,
    GENERALDELTA_REQUIREMENT,
    INTERNAL_PHASE_REQUIREMENT,
    REVLOG_COMPRESSION_ZSTD,
    REVLOGV1_REQUIREMENT,
    REVLOGV2_REQUIREMENT,
    SPARSEREVLOG_REQUIREMENT,
    TREEMANIFEST_REQUIREMENT,
}