Mercurial > hg
view tests/test-largefiles-small-disk.t @ 24735:07200e3332a1
tags: extract .hgtags filenodes cache to a standalone file
Resolution of .hgtags filenodes values has historically been a
performance pain point for large repositories, where reading individual
manifests can take over 100ms. Multiplied by hundreds or even thousands
of heads and resolving .hgtags filenodes becomes a performance issue.
This patch establishes a standalone cache file holding the .hgtags
filenodes for each changeset. After this patch, the .hgtags filenode
for any particular changeset should only have to be computed once
during the lifetime of the repository.
The introduced hgtagsfnodes1 cache file is modeled after the rev branch
cache: the cache is effectively an array of entries consisting of a
changeset fragment and the filenode for a revision. The file grows in
proportion to the length of the repository (24 bytes per changeset) and
is truncated when the repository is stripped. The file is not written
unless tag info is requested and tags have changed since last time.
This patch partially addresses issue4550. Future patches will split the
"tags" cache file into per-filter files and will refactor the cache
format to not capture the .hgtags fnodes, as these are now stored in
the hgtagsfnodes1 cache. This patch is capable of standing alone. We
should not have to wait on the tags cache filter split and format
refactor for this patch to land.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Wed, 15 Apr 2015 17:42:38 -0400 |
parents | 8a021cd38719 |
children | 7356e6b1f5b8 |
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Test how largefiles abort in case the disk runs full $ cat > criple.py <<EOF > import os, errno, shutil > from mercurial import util > # > # this makes the original largefiles code abort: > def copyfileobj(fsrc, fdst, length=16*1024): > fdst.write(fsrc.read(4)) > raise IOError(errno.ENOSPC, os.strerror(errno.ENOSPC)) > shutil.copyfileobj = copyfileobj > # > # this makes the rewritten code abort: > def filechunkiter(f, size=65536, limit=None): > yield f.read(4) > raise IOError(errno.ENOSPC, os.strerror(errno.ENOSPC)) > util.filechunkiter = filechunkiter > # > def oslink(src, dest): > raise OSError("no hardlinks, try copying instead") > util.oslink = oslink > EOF $ echo "[extensions]" >> $HGRCPATH $ echo "largefiles =" >> $HGRCPATH $ hg init alice $ cd alice $ echo "this is a very big file" > big $ hg add --large big $ hg commit --config extensions.criple=$TESTTMP/criple.py -m big abort: No space left on device [255] The largefile is not created in .hg/largefiles: $ ls .hg/largefiles dirstate The user cache is not even created: >>> import os; os.path.exists("$HOME/.cache/largefiles/") False Make the commit with space on the device: $ hg commit -m big Now make a clone with a full disk, and make sure lfutil.link function makes copies instead of hardlinks: $ cd .. $ hg --config extensions.criple=$TESTTMP/criple.py clone --pull alice bob requesting all changes adding changesets adding manifests adding file changes added 1 changesets with 1 changes to 1 files updating to branch default getting changed largefiles abort: No space left on device [255] The largefile is not created in .hg/largefiles: $ ls bob/.hg/largefiles dirstate