store: implement fncache basic path encoding in C
(This is not yet enabled; it will be turned on in a followup patch.)
The path encoding performed by fncache is complex and (perhaps
surprisingly) slow enough to negatively affect the overall performance
of Mercurial.
For a short path (< 120 bytes), the Python code can be reduced to a fairly
tractable state machine that either determines that nothing needs to be
done in a single pass, or performs the encoding in a second pass.
For longer paths, we avoid the more complicated hashed encoding scheme
for now, and fall back to Python.
Raw performance: I measured in a repo containing 150,000 files in its tip
manifest, with a median path name length of 57 bytes, and 95th percentile
of 96 bytes.
In this repo, the Python code takes 3.1 seconds to encode all path
names, while the hybrid C-and-Python code (called from Python) takes
0.21 seconds, for a speedup of about 14.
Across several other large repositories, I've measured the speedup from
the C code at between 26x and 40x.
For path names above 120 bytes where we must fall back to Python for
hashed encoding, the speedup is about 1.7x. Thus absolute performance
will depend strongly on the characteristics of a particular repository.
$ catpatch() {
> cat $1 | sed -e "s/^\(# Parent \).*/\1/"
> }
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ runtest() {
> hg init mq
> cd mq
>
> echo a > a
> hg ci -Ama
>
> echo '% qnew should refuse bad patch names'
> hg qnew series
> hg qnew status
> hg qnew guards
> hg qnew .
> hg qnew ..
> hg qnew .hgignore
> hg qnew .mqfoo
> hg qnew 'foo#bar'
> hg qnew 'foo:bar'
>
> hg qinit -c
>
> echo '% qnew with name containing slash'
> hg qnew foo/
> hg qnew foo/bar.patch
> hg qnew foo
> hg qseries
> hg qpop
> hg qdelete foo/bar.patch
>
> echo '% qnew with uncommitted changes'
> echo a > somefile
> hg add somefile
> hg qnew uncommitted.patch
> hg st
> hg qseries
>
> echo '% qnew implies add'
> hg -R .hg/patches st
>
> echo '% qnew missing'
> hg qnew missing.patch missing
>
> echo '% qnew -m'
> hg qnew -m 'foo bar' mtest.patch
> catpatch .hg/patches/mtest.patch
>
> echo '% qnew twice'
> hg qnew first.patch
> hg qnew first.patch
>
> touch ../first.patch
> hg qimport ../first.patch
>
> echo '% qnew -f from a subdirectory'
> hg qpop -a
> mkdir d
> cd d
> echo b > b
> hg ci -Am t
> echo b >> b
> hg st
> hg qnew -g -f p
> catpatch ../.hg/patches/p
>
> echo '% qnew -u with no username configured'
> HGUSER= hg qnew -u blue red
> catpatch ../.hg/patches/red
>
> echo '% qnew -e -u with no username configured'
> HGUSER= hg qnew -e -u chartreuse fucsia
> catpatch ../.hg/patches/fucsia
>
> echo '% fail when trying to import a merge'
> hg init merge
> cd merge
> touch a
> hg ci -Am null
> echo a >> a
> hg ci -m a
> hg up -r 0
> echo b >> a
> hg ci -m b
> hg merge -f 1
> hg resolve --mark a
> hg qnew -f merge
>
> cd ../../..
> rm -r mq
> }
plain headers
$ echo "[mq]" >> $HGRCPATH
$ echo "plain=true" >> $HGRCPATH
$ mkdir sandbox
$ (cd sandbox ; runtest)
adding a
% qnew should refuse bad patch names
abort: "series" cannot be used as the name of a patch
abort: "status" cannot be used as the name of a patch
abort: "guards" cannot be used as the name of a patch
abort: "." cannot be used as the name of a patch
abort: ".." cannot be used as the name of a patch
abort: patch name cannot begin with ".hg"
abort: patch name cannot begin with ".mq"
abort: "#" cannot be used in the name of a patch
abort: ":" cannot be used in the name of a patch
% qnew with name containing slash
abort: path ends in directory separator: foo/ (glob)
abort: "foo" already exists as a directory
foo/bar.patch
popping foo/bar.patch
patch queue now empty
% qnew with uncommitted changes
uncommitted.patch
% qnew implies add
A .hgignore
A series
A uncommitted.patch
% qnew missing
abort: missing: * (glob)
% qnew -m
foo bar
% qnew twice
abort: patch "first.patch" already exists
abort: patch "first.patch" already exists
% qnew -f from a subdirectory
popping first.patch
popping mtest.patch
popping uncommitted.patch
patch queue now empty
adding d/b
M d/b
diff --git a/d/b b/d/b
--- a/d/b
+++ b/d/b
@@ -1,1 +1,2 @@
b
+b
% qnew -u with no username configured
From: blue
% qnew -e -u with no username configured
From: chartreuse
% fail when trying to import a merge
adding a
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
created new head
merging a
warning: conflicts during merge.
merging a incomplete! (edit conflicts, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
abort: cannot manage merge changesets
$ rm -r sandbox
hg headers
$ echo "plain=false" >> $HGRCPATH
$ mkdir sandbox
$ (cd sandbox ; runtest)
adding a
% qnew should refuse bad patch names
abort: "series" cannot be used as the name of a patch
abort: "status" cannot be used as the name of a patch
abort: "guards" cannot be used as the name of a patch
abort: "." cannot be used as the name of a patch
abort: ".." cannot be used as the name of a patch
abort: patch name cannot begin with ".hg"
abort: patch name cannot begin with ".mq"
abort: "#" cannot be used in the name of a patch
abort: ":" cannot be used in the name of a patch
% qnew with name containing slash
abort: path ends in directory separator: foo/ (glob)
abort: "foo" already exists as a directory
foo/bar.patch
popping foo/bar.patch
patch queue now empty
% qnew with uncommitted changes
uncommitted.patch
% qnew implies add
A .hgignore
A series
A uncommitted.patch
% qnew missing
abort: missing: * (glob)
% qnew -m
# HG changeset patch
# Parent
foo bar
% qnew twice
abort: patch "first.patch" already exists
abort: patch "first.patch" already exists
% qnew -f from a subdirectory
popping first.patch
popping mtest.patch
popping uncommitted.patch
patch queue now empty
adding d/b
M d/b
# HG changeset patch
# Parent
diff --git a/d/b b/d/b
--- a/d/b
+++ b/d/b
@@ -1,1 +1,2 @@
b
+b
% qnew -u with no username configured
# HG changeset patch
# Parent
# User blue
% qnew -e -u with no username configured
# HG changeset patch
# Parent
# User chartreuse
% fail when trying to import a merge
adding a
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
created new head
merging a
warning: conflicts during merge.
merging a incomplete! (edit conflicts, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
abort: cannot manage merge changesets
$ rm -r sandbox