changegroup: compute seen files as changesets are added (
issue4750)
Before this patch, addchangegroup() would walk the changelog and compute
the set of seen files between applying changesets and applying
manifests. When cloning large repositories such as mozilla-central,
this consumed a non-trivial amount of time. On my MBP, this walk takes
~10s. On a dainty EC2 instance, this was measured to take ~125s! On the
latter machine, this delay was enough for the Mercurial server to
disconnect the client, thinking it had timed out, thus causing a clone
to abort.
This patch enables the changelog to compute the set of changed files as
new revisions are added. By doing so, we:
* avoid a potentially heavy computation between changelog and manifest
processing by spreading the computation across all changelog additions
* avoid extra reads from the changelog by operating on the data as it is
added
The downside of this is that the add revision callback does result in
extra I/O. Before, we would perform a flush (and subsequent read to
construct the full revision) when new delta chains were created. For
changelogs, this is typically every 2-4 revisions. Using the callback
guarantees there will be a flush after every added revision *and* an
open + read of the changelog to obtain the full revision in order to
read the added files. So, this increases the frequency of these
operations by the average chain length. In the future, the revlog
should be smart enough to know how to read revisions that haven't been
flushed yet, thus eliminating this extra I/O.
On my MBP, the total CPU times for an `hg unbundle` with a local
mozilla-central gzip bundle containing 251,934 changesets and 211,065
files did not have a statistically significant change with this patch,
holding steady around 360s. So, the increased revlog flushing did not
have an effect.
With this patch, there is no longer a visible pause between applying
changeset and manifest data. Before, it sure felt like Mercurial was
lethargic making this transition. Now, the transition is nearly
instantaneous, giving the impression that Mercurial is faster. Of course,
eliminating this pause means that the potential for network disconnect due
to channel inactivity during the changelog walk is eliminated as well.
And that is the impetus behind this change.
#require killdaemons
#if windows
$ hg clone http://localhost:$HGPORT/ copy
abort: * (glob)
[255]
#else
$ hg clone http://localhost:$HGPORT/ copy
abort: error: Connection refused
[255]
#endif
$ test -d copy
[1]
This server doesn't do range requests so it's basically only good for
one pull
$ python "$TESTDIR/dumbhttp.py" -p $HGPORT --pid dumb.pid
$ cat dumb.pid >> $DAEMON_PIDS
$ hg init remote
$ cd remote
$ echo foo > bar
$ echo c2 > '.dotfile with spaces'
$ hg add
adding .dotfile with spaces
adding bar
$ hg commit -m"test"
$ hg tip
changeset: 0:02770d679fb8
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: test
$ cd ..
$ hg clone static-http://localhost:$HGPORT/remote local
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 2 changes to 2 files
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd local
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
2 files, 1 changesets, 2 total revisions
$ cat bar
foo
$ cd ../remote
$ echo baz > quux
$ hg commit -A -mtest2
adding quux
check for HTTP opener failures when cachefile does not exist
$ rm .hg/cache/*
$ cd ../local
$ echo '[hooks]' >> .hg/hgrc
$ echo "changegroup = printenv.py changegroup" >> .hg/hgrc
$ hg pull
pulling from static-http://localhost:$HGPORT/remote
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
changegroup hook: HG_NODE=4ac2e3648604439c580c69b09ec9d93a88d93432 HG_SOURCE=pull HG_TXNID=TXN:* HG_URL=http://localhost:$HGPORT/remote (glob)
(run 'hg update' to get a working copy)
trying to push
$ hg update
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo more foo >> bar
$ hg commit -m"test"
$ hg push
pushing to static-http://localhost:$HGPORT/remote
abort: destination does not support push
[255]
trying clone -r
$ cd ..
$ hg clone -r doesnotexist static-http://localhost:$HGPORT/remote local0
abort: unknown revision 'doesnotexist'!
[255]
$ hg clone -r 0 static-http://localhost:$HGPORT/remote local0
adding changesets
adding manifests
adding file changes
added 1 changesets with 2 changes to 2 files
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
test with "/" URI (issue747) and subrepo
$ hg init
$ hg init sub
$ touch sub/test
$ hg -R sub commit -A -m "test"
adding test
$ hg -R sub tag not-empty
$ echo sub=sub > .hgsub
$ echo a > a
$ hg add a .hgsub
$ hg -q ci -ma
$ hg clone static-http://localhost:$HGPORT/ local2
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 3 changes to 3 files
updating to branch default
cloning subrepo sub from static-http://localhost:$HGPORT/sub
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd local2
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
3 files, 1 changesets, 3 total revisions
checking subrepo links
$ cat a
a
$ hg paths
default = static-http://localhost:$HGPORT/
test with empty repo (issue965)
$ cd ..
$ hg init remotempty
$ hg clone static-http://localhost:$HGPORT/remotempty local3
no changes found
updating to branch default
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd local3
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
0 files, 0 changesets, 0 total revisions
$ hg paths
default = static-http://localhost:$HGPORT/remotempty
test with non-repo
$ cd ..
$ mkdir notarepo
$ hg clone static-http://localhost:$HGPORT/notarepo local3
abort: 'http://localhost:$HGPORT/notarepo' does not appear to be an hg repository!
[255]
$ killdaemons.py