Mercurial > hg
view mercurial/requirements.py @ 47120:7109a38830c9
dirstate-tree: Fold "tracked descendants" counter update in main walk
For the purpose of implementing `has_tracked_dir` (which means "has tracked
descendants) without an expensive sub-tree traversal, we maintaing a counter
of tracked descendants on each "directory" node of the tree-shaped dirstate.
Before this changeset, mutating or inserting a node at a given path would
involve:
* Walking the tree from root through ancestors to find the node or the spot
where to insert it
* Looking at the previous node if any to decide what counter update is needed
* Performing any node mutation
* Walking the tree *again* to update counters in ancestor nodes
When profiling `hg status` on a large repo, this second walk takes times
while loading a the dirstate from disk.
It turns out we have enough information to decide before he first tree walk
what counter update is needed. This changeset merges the two walks, gaining
~10% of the total time for `hg update` (in the same hyperfine benchmark as
the previous changeset).
---
Profiling was done by compiling with this `.cargo/config`:
[profile.release]
debug = true
then running with:
py-spy record -r 500 -n -o /tmp/hg.json --format speedscope -- \
./hg status -R $REPO --config experimental.dirstate-tree.in-memory=1
then visualizing the recorded JSON file in https://www.speedscope.app/
Differential Revision: https://phab.mercurial-scm.org/D10554
author | Simon Sapin <simon.sapin@octobus.net> |
---|---|
date | Fri, 30 Apr 2021 14:22:14 +0200 |
parents | d4ba4d51f85f |
children | 21b3e6116bd1 |
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# requirements.py - objects and functions related to repository requirements # # Copyright 2005-2007 Olivia Mackall <olivia@selenic.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import GENERALDELTA_REQUIREMENT = b'generaldelta' DOTENCODE_REQUIREMENT = b'dotencode' STORE_REQUIREMENT = b'store' FNCACHE_REQUIREMENT = b'fncache' # 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' # Stores manifest in Tree structure TREEMANIFEST_REQUIREMENT = b'treemanifest' REVLOGV1_REQUIREMENT = b'revlogv1' # 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 sidedataflag requirement will allow to store extra # information for revision without altering their original hashes. SIDEDATA_REQUIREMENT = b'exp-sidedata-flag' # 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' # 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 WORKING_DIR_REQUIREMENTS = { SPARSE_REQUIREMENT, SHARED_REQUIREMENT, RELATIVE_SHARED_REQUIREMENT, SHARESAFE_REQUIREMENT, }