Mercurial > hg-stable
view tests/test-convert-p4.t @ 32200:4d504e541d3d
rebase: use matcher to optimize manifestmerge
The old merge code would call manifestmerge and calculate the complete diff
between the source to the destination. In many cases, like rebase, the vast
majority of differences between the source and destination are irrelevant
because they are differences between the destination and the common ancestor
only, and therefore don't affect the merge. Since most actions are 'keep', all
the effort to compute them is wasted.
Instead, let's compute the difference between the source and the common ancestor
and only perform the diff of those files against the merge destination. When
using treemanifest, this lets us avoid loading almost the entire tree when
rebasing from a very old ancestor. This speeds up rebase of an old stack of 27
commits by 20x.
In mozilla-central, without treemanifest, when rebasing a commit from
default~100000 to default, this speeds up the manifestmerge step from 2.6s to
1.2s. However, the additional diff adds an overhead to all manifestmerge calls,
especially for flat manifests. When rebasing a commit from default~1 to default
it appears to add 100ms in mozilla-central. While we could put this optimization
behind a flag, I think the fact that it makes merge O(number of changes being
applied) instead of O(number of changes between X and Y) justifies it.
author | Durham Goode <durham@fb.com> |
---|---|
date | Wed, 03 May 2017 10:43:59 -0700 |
parents | 78ac8acfc4bd |
children |
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#require p4 $ echo "[extensions]" >> $HGRCPATH $ echo "convert = " >> $HGRCPATH create p4 depot $ P4ROOT=`pwd`/depot; export P4ROOT $ P4AUDIT=$P4ROOT/audit; export P4AUDIT $ P4JOURNAL=$P4ROOT/journal; export P4JOURNAL $ P4LOG=$P4ROOT/log; export P4LOG $ P4PORT=localhost:$HGPORT; export P4PORT $ P4DEBUG=1; export P4DEBUG start the p4 server $ [ ! -d $P4ROOT ] && mkdir $P4ROOT $ p4d -f -J off >$P4ROOT/stdout 2>$P4ROOT/stderr & $ echo $! >> $DAEMON_PIDS $ trap "echo stopping the p4 server ; p4 admin stop" EXIT $ # wait for the server to initialize $ while ! p4 ; do > sleep 1 > done >/dev/null 2>/dev/null create a client spec $ P4CLIENT=hg-p4-import; export P4CLIENT $ DEPOTPATH=//depot/test-mercurial-import/... $ p4 client -o | sed '/^View:/,$ d' >p4client $ echo View: >>p4client $ echo " $DEPOTPATH //$P4CLIENT/..." >>p4client $ p4 client -i <p4client Client hg-p4-import saved. populate the depot $ echo a > a $ mkdir b $ echo c > b/c $ p4 add a b/c //depot/test-mercurial-import/a#1 - opened for add //depot/test-mercurial-import/b/c#1 - opened for add $ p4 submit -d initial Submitting change 1. Locking 2 files ... add //depot/test-mercurial-import/a#1 add //depot/test-mercurial-import/b/c#1 Change 1 submitted. change some files $ p4 edit a //depot/test-mercurial-import/a#1 - opened for edit $ echo aa >> a $ p4 submit -d "change a" Submitting change 2. Locking 1 files ... edit //depot/test-mercurial-import/a#2 Change 2 submitted. $ p4 edit b/c //depot/test-mercurial-import/b/c#1 - opened for edit $ echo cc >> b/c $ p4 submit -d "change b/c" Submitting change 3. Locking 1 files ... edit //depot/test-mercurial-import/b/c#2 Change 3 submitted. convert $ hg convert -s p4 $DEPOTPATH dst initializing destination dst repository scanning source... reading p4 views collecting p4 changelists 1 initial 2 change a 3 change b/c sorting... converting... 2 initial 1 change a 0 change b/c $ hg -R dst log --template 'rev={rev} desc="{desc}" tags="{tags}" files="{files}"\n' rev=2 desc="change b/c" tags="tip" files="b/c" rev=1 desc="change a" tags="" files="a" rev=0 desc="initial" tags="" files="a b/c" change some files $ p4 edit a b/c //depot/test-mercurial-import/a#2 - opened for edit //depot/test-mercurial-import/b/c#2 - opened for edit $ echo aaa >> a $ echo ccc >> b/c $ p4 submit -d "change a b/c" Submitting change 4. Locking 2 files ... edit //depot/test-mercurial-import/a#3 edit //depot/test-mercurial-import/b/c#3 Change 4 submitted. convert again $ hg convert -s p4 $DEPOTPATH dst scanning source... reading p4 views collecting p4 changelists 4 change a b/c sorting... converting... 0 change a b/c $ hg -R dst log --template 'rev={rev} desc="{desc}" tags="{tags}" files="{files}"\n' rev=3 desc="change a b/c" tags="tip" files="a b/c" rev=2 desc="change b/c" tags="" files="b/c" rev=1 desc="change a" tags="" files="a" rev=0 desc="initial" tags="" files="a b/c" interesting names $ echo dddd > "d d" $ mkdir " e" $ echo fff >" e/ f" $ p4 add "d d" " e/ f" //depot/test-mercurial-import/d d#1 - opened for add //depot/test-mercurial-import/ e/ f#1 - opened for add $ p4 submit -d "add d e f" Submitting change 5. Locking 2 files ... add //depot/test-mercurial-import/ e/ f#1 add //depot/test-mercurial-import/d d#1 Change 5 submitted. convert again $ hg convert -s p4 $DEPOTPATH dst scanning source... reading p4 views collecting p4 changelists 5 add d e f sorting... converting... 0 add d e f $ hg -R dst log --template 'rev={rev} desc="{desc}" tags="{tags}" files="{files}"\n' rev=4 desc="add d e f" tags="tip" files=" e/ f d d" rev=3 desc="change a b/c" tags="" files="a b/c" rev=2 desc="change b/c" tags="" files="b/c" rev=1 desc="change a" tags="" files="a" rev=0 desc="initial" tags="" files="a b/c" empty commit message $ p4 edit a //depot/test-mercurial-import/a#3 - opened for edit $ echo aaaaa >> a $ p4 submit -d "" Submitting change 6. Locking 1 files ... edit //depot/test-mercurial-import/a#4 Change 6 submitted. $ hg convert -s p4 $DEPOTPATH dst scanning source... reading p4 views collecting p4 changelists 6 **empty changelist description** sorting... converting... 0 exit trap: stopping the p4 server