Mercurial > hg
view tests/test-diff-upgrade.t @ 23785:cb99bacb9b4e
branchcache: introduce revbranchcache for caching of revision branch names
It is expensive to retrieve the branch name of a revision. Very expensive when
creating a changectx and calling .branch() every time - slightly less when
using changelog.branchinfo().
Now, to speed things up, provide a way to cache the results on disk in an
efficient format. Each branchname is assigned a number, and for each revision
we store the number of the corresponding branch name. The branch names are
stored in a dedicated file which is strictly append only.
Branch names are usually reused across several revisions, and the total list of
branch names will thus be so small that it is feasible to read the whole set of
names before using the cache. It will however do that it might be more
efficient to use the changelog for retrieving the branch info for a single
revision.
The revision entries are stored in another file. This file is usually append
only, but if the repository has been modified, the file will be truncated and
the relevant parts rewritten on demand.
The entries for each revision are 8 bytes each, and the whole revision file
will thus be 1/8 of 00changelog.i.
Each revision entry contains the first 4 bytes of the corresponding node hash.
This is used as a check sum that always is verified before the entry is used.
That check is relatively expensive but it makes sure history modification is
detected and handled correctly. It will also detect and handle most revision
file corruptions.
This is just a cache. A new format can always be introduced if other
requirements or ideas make that seem like a good idea. Rebuilding the cache is
not really more expensive than it was to run for example 'hg log -b branchname'
before this cache was introduced.
This new method is still unused but promise to make some operations several
times faster once it actually is used.
Abandoning Python 2.4 would make it possible to implement this more efficiently
by using struct classes and pack_into. The Python code could probably also be
micro optimized or it could be implemented very efficiently in C where it would
be easy to control the data access.
| author | Mads Kiilerich <madski@unity3d.com> |
|---|---|
| date | Thu, 08 Jan 2015 00:01:03 +0100 |
| parents | e955549cd045 |
| children | 15ddf83fbf84 |
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#require execbit $ cat <<EOF >> $HGRCPATH > [extensions] > autodiff = $TESTDIR/autodiff.py > [diff] > nodates = 1 > EOF $ hg init repo $ cd repo make a combination of new, changed and deleted file $ echo regular > regular $ echo rmregular > rmregular $ $PYTHON -c "file('bintoregular', 'wb').write('\0')" $ touch rmempty $ echo exec > exec $ chmod +x exec $ echo rmexec > rmexec $ chmod +x rmexec $ echo setexec > setexec $ echo unsetexec > unsetexec $ chmod +x unsetexec $ echo binary > binary $ $PYTHON -c "file('rmbinary', 'wb').write('\0')" $ hg ci -Am addfiles adding binary adding bintoregular adding exec adding regular adding rmbinary adding rmempty adding rmexec adding rmregular adding setexec adding unsetexec $ echo regular >> regular $ echo newregular >> newregular $ rm rmempty $ touch newempty $ rm rmregular $ echo exec >> exec $ echo newexec > newexec $ echo bintoregular > bintoregular $ chmod +x newexec $ rm rmexec $ chmod +x setexec $ chmod -x unsetexec $ $PYTHON -c "file('binary', 'wb').write('\0\0')" $ $PYTHON -c "file('newbinary', 'wb').write('\0')" $ rm rmbinary $ hg addremove -s 0 adding newbinary adding newempty adding newexec adding newregular removing rmbinary removing rmempty removing rmexec removing rmregular git=no: regular diff for all files $ hg autodiff --git=no diff -r a66d19b9302d binary Binary file binary has changed diff -r a66d19b9302d bintoregular Binary file bintoregular has changed diff -r a66d19b9302d exec --- a/exec +++ b/exec @@ -1,1 +1,2 @@ exec +exec diff -r a66d19b9302d newbinary Binary file newbinary has changed diff -r a66d19b9302d newexec --- /dev/null +++ b/newexec @@ -0,0 +1,1 @@ +newexec diff -r a66d19b9302d newregular --- /dev/null +++ b/newregular @@ -0,0 +1,1 @@ +newregular diff -r a66d19b9302d regular --- a/regular +++ b/regular @@ -1,1 +1,2 @@ regular +regular diff -r a66d19b9302d rmbinary Binary file rmbinary has changed diff -r a66d19b9302d rmexec --- a/rmexec +++ /dev/null @@ -1,1 +0,0 @@ -rmexec diff -r a66d19b9302d rmregular --- a/rmregular +++ /dev/null @@ -1,1 +0,0 @@ -rmregular git=yes: git diff for single regular file $ hg autodiff --git=yes regular diff --git a/regular b/regular --- a/regular +++ b/regular @@ -1,1 +1,2 @@ regular +regular git=auto: regular diff for regular files and non-binary removals $ hg autodiff --git=auto regular newregular rmregular rmexec diff -r a66d19b9302d newregular --- /dev/null +++ b/newregular @@ -0,0 +1,1 @@ +newregular diff -r a66d19b9302d regular --- a/regular +++ b/regular @@ -1,1 +1,2 @@ regular +regular diff -r a66d19b9302d rmexec --- a/rmexec +++ /dev/null @@ -1,1 +0,0 @@ -rmexec diff -r a66d19b9302d rmregular --- a/rmregular +++ /dev/null @@ -1,1 +0,0 @@ -rmregular $ for f in exec newexec setexec unsetexec binary newbinary newempty rmempty rmbinary bintoregular; do > echo > echo '% git=auto: git diff for' $f > hg autodiff --git=auto $f > done % git=auto: git diff for exec diff -r a66d19b9302d exec --- a/exec +++ b/exec @@ -1,1 +1,2 @@ exec +exec % git=auto: git diff for newexec diff --git a/newexec b/newexec new file mode 100755 --- /dev/null +++ b/newexec @@ -0,0 +1,1 @@ +newexec % git=auto: git diff for setexec diff --git a/setexec b/setexec old mode 100644 new mode 100755 % git=auto: git diff for unsetexec diff --git a/unsetexec b/unsetexec old mode 100755 new mode 100644 % git=auto: git diff for binary diff --git a/binary b/binary index a9128c283485202893f5af379dd9beccb6e79486..09f370e38f498a462e1ca0faa724559b6630c04f GIT binary patch literal 2 Jc${Nk0000200961 % git=auto: git diff for newbinary diff --git a/newbinary b/newbinary new file mode 100644 index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..f76dd238ade08917e6712764a16a22005a50573d GIT binary patch literal 1 Ic${MZ000310RR91 % git=auto: git diff for newempty diff --git a/newempty b/newempty new file mode 100644 % git=auto: git diff for rmempty diff --git a/rmempty b/rmempty deleted file mode 100644 % git=auto: git diff for rmbinary diff --git a/rmbinary b/rmbinary deleted file mode 100644 index f76dd238ade08917e6712764a16a22005a50573d..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 GIT binary patch literal 0 Hc$@<O00001 % git=auto: git diff for bintoregular diff --git a/bintoregular b/bintoregular index f76dd238ade08917e6712764a16a22005a50573d..9c42f2b6427d8bf034b7bc23986152dc01bfd3ab GIT binary patch literal 13 Uc$`bh%qz(+N=+}#Ni5<5043uE82|tP git=warn: regular diff with data loss warnings $ hg autodiff --git=warn diff -r a66d19b9302d binary Binary file binary has changed diff -r a66d19b9302d bintoregular Binary file bintoregular has changed diff -r a66d19b9302d exec --- a/exec +++ b/exec @@ -1,1 +1,2 @@ exec +exec diff -r a66d19b9302d newbinary Binary file newbinary has changed diff -r a66d19b9302d newexec --- /dev/null +++ b/newexec @@ -0,0 +1,1 @@ +newexec diff -r a66d19b9302d newregular --- /dev/null +++ b/newregular @@ -0,0 +1,1 @@ +newregular diff -r a66d19b9302d regular --- a/regular +++ b/regular @@ -1,1 +1,2 @@ regular +regular diff -r a66d19b9302d rmbinary Binary file rmbinary has changed diff -r a66d19b9302d rmexec --- a/rmexec +++ /dev/null @@ -1,1 +0,0 @@ -rmexec diff -r a66d19b9302d rmregular --- a/rmregular +++ /dev/null @@ -1,1 +0,0 @@ -rmregular data lost for: binary data lost for: bintoregular data lost for: newbinary data lost for: newempty data lost for: newexec data lost for: rmbinary data lost for: rmempty data lost for: setexec data lost for: unsetexec git=abort: fail on execute bit change $ hg autodiff --git=abort regular setexec abort: losing data for setexec [255] git=abort: succeed on regular file $ hg autodiff --git=abort regular diff -r a66d19b9302d regular --- a/regular +++ b/regular @@ -1,1 +1,2 @@ regular +regular $ cd ..