branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
$ cat >> $HGRCPATH << EOF
> [extensions]
> fastannotate=
> [fastannotate]
> mainbranch=@
> EOF
setup the server repo
$ hg init repo-server
$ cd repo-server
$ cat >> .hg/hgrc << EOF
> [fastannotate]
> server=1
> EOF
$ for i in 1 2 3 4; do
> echo $i >> a
> hg commit -A -m $i a
> done
$ [ -d .hg/fastannotate ]
[1]
$ hg bookmark @
$ cd ..
setup the local repo
$ hg clone 'ssh://user@dummy/repo-server' repo-local -q
$ cd repo-local
$ cat >> .hg/hgrc << EOF
> [fastannotate]
> client=1
> clientfetchthreshold=0
> EOF
$ [ -d .hg/fastannotate ]
[1]
$ hg fastannotate a --debug
running * (glob)
sending hello command
sending between command
remote: * (glob) (?)
remote: capabilities: * (glob)
remote: * (glob) (?)
sending protocaps command
fastannotate: requesting 1 files
sending getannotate command
fastannotate: writing 112 bytes to fastannotate/default/a.l
fastannotate: writing 94 bytes to fastannotate/default/a.m
fastannotate: a: using fast path (resolved fctx: True)
0: 1
1: 2
2: 3
3: 4
the cache could be reused and no download is necessary
$ hg fastannotate a --debug
fastannotate: a: using fast path (resolved fctx: True)
0: 1
1: 2
2: 3
3: 4
if the client agrees where the head of the master branch is, no re-download
happens even if the client has more commits
$ echo 5 >> a
$ hg commit -m 5
$ hg bookmark -r 3 @ -f
$ hg fastannotate a --debug
0: 1
1: 2
2: 3
3: 4
4: 5
if the client has a different "@" (head of the master branch) and "@" is ahead
of the server, the server can detect things are unchanged and does not return
full contents (not that there is no "writing ... to fastannotate"), but the
client can also build things up on its own (causing diverge)
$ hg bookmark -r 4 @ -f
$ hg fastannotate a --debug
running * (glob)
sending hello command
sending between command
remote: * (glob) (?)
remote: capabilities: * (glob)
remote: * (glob) (?)
sending protocaps command
fastannotate: requesting 1 files
sending getannotate command
fastannotate: a: 1 new changesets in the main branch
0: 1
1: 2
2: 3
3: 4
4: 5
if the client has a different "@" which is behind the server. no download is
necessary
$ hg fastannotate a --debug --config fastannotate.mainbranch=2
fastannotate: a: using fast path (resolved fctx: True)
0: 1
1: 2
2: 3
3: 4
4: 5
define fastannotate on-disk paths
$ p1=.hg/fastannotate/default
$ p2=../repo-server/.hg/fastannotate/default
revert bookmark change so the client is behind the server
$ hg bookmark -r 2 @ -f
in the "fctx" mode with the "annotate" command, the client also downloads the
cache. but not in the (default) "fastannotate" mode.
$ rm $p1/a.l $p1/a.m
$ hg annotate a --debug | grep 'fastannotate: writing'
[1]
$ hg annotate a --config fastannotate.modes=fctx --debug | grep 'fastannotate: writing' | sort
fastannotate: writing 112 bytes to fastannotate/default/a.l
fastannotate: writing 94 bytes to fastannotate/default/a.m
the fastannotate cache (built server-side, downloaded client-side) in two repos
have the same content (because the client downloads from the server)
$ diff $p1/a.l $p2/a.l
$ diff $p1/a.m $p2/a.m
in the "fctx" mode, the client could also build the cache locally
$ hg annotate a --config fastannotate.modes=fctx --debug --config fastannotate.mainbranch=4 | grep fastannotate
fastannotate: requesting 1 files
fastannotate: a: 1 new changesets in the main branch
the server would rebuild broken cache automatically
$ cp $p2/a.m $p2/a.m.bak
$ echo BROKEN1 > $p1/a.m
$ echo BROKEN2 > $p2/a.m
$ hg fastannotate a --debug | grep 'fastannotate: writing' | sort
fastannotate: writing 112 bytes to fastannotate/default/a.l
fastannotate: writing 94 bytes to fastannotate/default/a.m
$ diff $p1/a.m $p2/a.m
$ diff $p2/a.m $p2/a.m.bak
use the "debugbuildannotatecache" command to build annotate cache
$ rm -rf $p1 $p2
$ hg --cwd ../repo-server debugbuildannotatecache a --debug
fastannotate: a: 4 new changesets in the main branch
$ hg --cwd ../repo-local debugbuildannotatecache a --debug
running * (glob)
sending hello command
sending between command
remote: * (glob) (?)
remote: capabilities: * (glob)
remote: * (glob) (?)
sending protocaps command
fastannotate: requesting 1 files
sending getannotate command
fastannotate: writing * (glob)
fastannotate: writing * (glob)
$ diff $p1/a.l $p2/a.l
$ diff $p1/a.m $p2/a.m
with the clientfetchthreshold config option, the client can build up the cache
without downloading from the server
$ rm -rf $p1
$ hg fastannotate a --debug --config fastannotate.clientfetchthreshold=10
fastannotate: a: 3 new changesets in the main branch
0: 1
1: 2
2: 3
3: 4
4: 5
if the fastannotate directory is not writable, the fctx mode still works
$ rm -rf $p1
$ touch $p1
$ hg annotate a --debug --traceback --config fastannotate.modes=fctx
fastannotate: a: cache broken and deleted
fastannotate: prefetch failed: * (glob)
fastannotate: a: cache broken and deleted
fastannotate: falling back to the vanilla annotate: * (glob)
0: 1
1: 2
2: 3
3: 4
4: 5
with serverbuildondemand=False, the server will not build anything
$ cat >> ../repo-server/.hg/hgrc <<EOF
> [fastannotate]
> serverbuildondemand=False
> EOF
$ rm -rf $p1 $p2
$ hg fastannotate a --debug | grep 'fastannotate: writing'
[1]