view tests/test-subrepo-svn.t @ 26623:5a95fe44121d

clonebundles: support for seeding clones from pre-generated bundles

Cloning can be an expensive operation for servers because the server
generates a bundle from existing repository data at request time. For
a large repository like mozilla-central, this consumes 4+ minutes
of CPU time on the server. It also results in significant network
utilization. Multiplied by hundreds or even thousands of clients and
the ensuing load can result in difficulties scaling the Mercurial server.

Despite generation of bundles being deterministic until the next
changeset is added, the generation of bundles to service a clone request
is not cached. Each clone thus performs redundant work. This is
wasteful.

This patch introduces the "clonebundles" extension and related
client-side functionality to help alleviate this deficiency. The
client-side feature is behind an experimental flag and is not enabled by
default.

It works as follows:

1) Server operator generates a bundle and makes it available on a
   server (likely HTTP).
2) Server operator defines the URL of a bundle file in a
   .hg/clonebundles.manifest file.
3) Client `hg clone`ing sees the server is advertising bundle URLs.
4) Client fetches and applies the advertised bundle.
5) Client performs equivalent of `hg pull` to fetch changes made since
   the bundle was created.

Essentially, the server performs the expensive work of generating a
bundle once and all subsequent clones fetch a static file from
somewhere. Scaling static file serving is a much more manageable
problem than scaling a Python application like Mercurial. Assuming your
repository grows less than 1% per day, the end result is 99+% of CPU
and network load from clones is eliminated, allowing Mercurial servers
to scale more easily. Serving static files also means data can be
transferred to clients as fast as they can consume it, rather than as
fast as servers can generate it. This makes clones faster.

Mozilla has implemented similar functionality of this patch on
hg.mozilla.org using a custom extension. We are hosting bundle files in
Amazon S3 and CloudFront (a CDN) and have successfully offloaded
>1 TB/day in data transfer from hg.mozilla.org, freeing up significant
bandwidth and CPU resources. The positive impact has been stellar and
I believe it has proved its value to be included in Mercurial core. I
feel it is important for the client-side support to be enabled in core
by default because it means that clients will get faster, more reliable
clones and will enable server operators to reduce load without
requiring any client-side configuration changes (assuming clients are
up to date, of course).

The scope of this feature is narrowly and specifically tailored to
cloning, despite "serve pulls from pre-generated bundles" being a valid
and useful feature. I would eventually like for Mercurial servers to
support transferring *all* repository data via statically hosted files.
You could imagine a server that siphons all pushed data to bundle files
and instructs clients to apply a stream of bundles to reconstruct all
repository data. This feature, while useful and powerful, is
significantly more work to implement because it requires the server
component have awareness of discovery and a mapping of which changesets
are in which files. Full, clone bundles, by contrast, are much simpler.

The wire protocol command is named "clonebundles" instead of something
more generic like "staticbundles" to leave the door open for a new, more
powerful and more generic server-side component with minimal backwards
compatibility implications. The name "bundleclone" is used by Mozilla's
extension and would cause problems since there are subtle differences
in Mozilla's extension.

Mozilla's experience with this idea has taught us that some form of
"content negotiation" is required. Not all clients will support all
bundle formats or even URLs (advanced TLS requirements, etc). To ensure
the highest uptake possible, a server needs to advertise multiple
versions of bundles and clients need to be able to choose the most
appropriate from that list one. The "attributes" in each
server-advertised entry facilitate this filtering and sorting. Their
use will become apparent in subsequent patches.

Initial inspiration and credit for the idea of cloning from static files
belongs to Augie Fackler and his "lookaside clone" extension proof of
concept.

#require svn15

  $ SVNREPOPATH=`pwd`/svn-repo
#if windows
  $ SVNREPOURL=file:///`$PYTHON -c "import urllib, sys; sys.stdout.write(urllib.quote(sys.argv[1]))" "$SVNREPOPATH"`
#else
  $ SVNREPOURL=file://`$PYTHON -c "import urllib, sys; sys.stdout.write(urllib.quote(sys.argv[1]))" "$SVNREPOPATH"`
#endif

  $ filter_svn_output () {
  >     egrep -v 'Committing|Transmitting|Updating' || true
  > }

create subversion repo

  $ WCROOT="`pwd`/svn-wc"
  $ svnadmin create svn-repo
  $ svn co "$SVNREPOURL" svn-wc
  Checked out revision 0.
  $ cd svn-wc
  $ mkdir src
  $ echo alpha > src/alpha
  $ svn add src
  A         src
  A         src/alpha (glob)
  $ mkdir externals
  $ echo other > externals/other
  $ svn add externals
  A         externals
  A         externals/other (glob)
  $ svn ci -qm 'Add alpha'
  $ svn up -q
  $ echo "externals -r1 $SVNREPOURL/externals" > extdef
  $ svn propset -F extdef svn:externals src
  property 'svn:externals' set on 'src'
  $ svn ci -qm 'Setting externals'
  $ cd ..

create hg repo

  $ mkdir sub
  $ cd sub
  $ hg init t
  $ cd t

first revision, no sub

  $ echo a > a
  $ hg ci -Am0
  adding a

add first svn sub with leading whitespaces

  $ echo "s =        [svn]       $SVNREPOURL/src" >> .hgsub
  $ echo "subdir/s = [svn]       $SVNREPOURL/src" >> .hgsub
  $ svn co --quiet "$SVNREPOURL"/src s
  $ mkdir subdir
  $ svn co --quiet "$SVNREPOURL"/src subdir/s
  $ hg add .hgsub
  $ hg ci -m1

make sure we avoid empty commits (issue2445)

  $ hg sum
  parent: 1:* tip (glob)
   1
  branch: default
  commit: (clean)
  update: (current)
  phases: 2 draft
  $ hg ci -moops
  nothing changed
  [1]

debugsub

  $ hg debugsub
  path s
   source   file://*/svn-repo/src (glob)
   revision 2
  path subdir/s
   source   file://*/svn-repo/src (glob)
   revision 2

change file in svn and hg, commit

  $ echo a >> a
  $ echo alpha >> s/alpha
  $ hg sum
  parent: 1:* tip (glob)
   1
  branch: default
  commit: 1 modified, 1 subrepos
  update: (current)
  phases: 2 draft
  $ hg commit --subrepos -m 'Message!' | filter_svn_output
  committing subrepository s
  Sending*s/alpha (glob)
  Committed revision 3.
  
  Fetching external item into '*s/externals'* (glob)
  External at revision 1.
  
  At revision 3.
  $ hg debugsub
  path s
   source   file://*/svn-repo/src (glob)
   revision 3
  path subdir/s
   source   file://*/svn-repo/src (glob)
   revision 2

missing svn file, commit should fail

  $ rm s/alpha
  $ hg commit --subrepos -m 'abort on missing file'
  committing subrepository s
  abort: cannot commit missing svn entries (in subrepo s)
  [255]
  $ svn revert s/alpha > /dev/null

add an unrelated revision in svn and update the subrepo to without
bringing any changes.

  $ svn mkdir "$SVNREPOURL/unrelated" -qm 'create unrelated'
  $ svn up -q s
  $ hg sum
  parent: 2:* tip (glob)
   Message!
  branch: default
  commit: (clean)
  update: (current)
  phases: 3 draft

  $ echo a > s/a

should be empty despite change to s/a

  $ hg st

add a commit from svn

  $ cd "$WCROOT/src"
  $ svn up -q
  $ echo xyz >> alpha
  $ svn propset svn:mime-type 'text/xml' alpha
  property 'svn:mime-type' set on 'alpha'
  $ svn ci -qm 'amend a from svn'
  $ cd ../../sub/t

this commit from hg will fail

  $ echo zzz >> s/alpha
  $ (hg ci --subrepos -m 'amend alpha from hg' 2>&1; echo "[$?]") | grep -vi 'out of date'
  committing subrepository s
  abort: svn:*Commit failed (details follow): (glob)
  [255]
  $ svn revert -q s/alpha

this commit fails because of meta changes

  $ svn propset svn:mime-type 'text/html' s/alpha
  property 'svn:mime-type' set on 's/alpha' (glob)
  $ (hg ci --subrepos -m 'amend alpha from hg' 2>&1; echo "[$?]") | grep -vi 'out of date'
  committing subrepository s
  abort: svn:*Commit failed (details follow): (glob)
  [255]
  $ svn revert -q s/alpha

this commit fails because of externals changes

  $ echo zzz > s/externals/other
  $ hg ci --subrepos -m 'amend externals from hg'
  committing subrepository s
  abort: cannot commit svn externals (in subrepo s)
  [255]
  $ hg diff --subrepos -r 1:2 | grep -v diff
  --- a/.hgsubstate	Thu Jan 01 00:00:00 1970 +0000
  +++ b/.hgsubstate	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,2 +1,2 @@
  -2 s
  +3 s
   2 subdir/s
  --- a/a	Thu Jan 01 00:00:00 1970 +0000
  +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,2 @@
   a
  +a
  $ svn revert -q s/externals/other

this commit fails because of externals meta changes

  $ svn propset svn:mime-type 'text/html' s/externals/other
  property 'svn:mime-type' set on 's/externals/other' (glob)
  $ hg ci --subrepos -m 'amend externals from hg'
  committing subrepository s
  abort: cannot commit svn externals (in subrepo s)
  [255]
  $ svn revert -q s/externals/other

clone

  $ cd ..
  $ hg clone t tc
  updating to branch default
  A    tc/s/alpha (glob)
   U   tc/s (glob)
  
  Fetching external item into 'tc/s/externals'* (glob)
  A    tc/s/externals/other (glob)
  Checked out external at revision 1.
  
  Checked out revision 3.
  A    tc/subdir/s/alpha (glob)
   U   tc/subdir/s (glob)
  
  Fetching external item into 'tc/subdir/s/externals'* (glob)
  A    tc/subdir/s/externals/other (glob)
  Checked out external at revision 1.
  
  Checked out revision 2.
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd tc

debugsub in clone

  $ hg debugsub
  path s
   source   file://*/svn-repo/src (glob)
   revision 3
  path subdir/s
   source   file://*/svn-repo/src (glob)
   revision 2

verify subrepo is contained within the repo directory

  $ $PYTHON -c "import os.path; print os.path.exists('s')"
  True

update to nullrev (must delete the subrepo)

  $ hg up null
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ ls

Check hg update --clean
  $ cd "$TESTTMP/sub/t"
  $ cd s
  $ echo c0 > alpha
  $ echo c1 > f1
  $ echo c1 > f2
  $ svn add f1 -q
  $ svn status | sort
  
  ? *    a (glob)
  ? *    f2 (glob)
  A *    f1 (glob)
  M *    alpha (glob)
  Performing status on external item at 'externals'* (glob)
  X *    externals (glob)
  $ cd ../..
  $ hg -R t update -C
  
  Fetching external item into 't/s/externals'* (glob)
  Checked out external at revision 1.
  
  Checked out revision 3.
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd t/s
  $ svn status | sort
  
  ? *    a (glob)
  ? *    f1 (glob)
  ? *    f2 (glob)
  Performing status on external item at 'externals'* (glob)
  X *    externals (glob)

Sticky subrepositories, no changes
  $ cd "$TESTTMP/sub/t"
  $ hg id -n
  2
  $ cd s
  $ svnversion
  3
  $ cd ..
  $ hg update 1
  U    *s/alpha (glob)
  
  Fetching external item into '*s/externals'* (glob)
  Checked out external at revision 1.
  
  Checked out revision 2.
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id -n
  1
  $ cd s
  $ svnversion
  2
  $ cd ..

Sticky subrepositories, file changes
  $ touch s/f1
  $ cd s
  $ svn add f1
  A         f1
  $ cd ..
  $ hg id -n
  1+
  $ cd s
  $ svnversion
  2M
  $ cd ..
  $ hg update tip
   subrepository s diverged (local revision: 2, remote revision: 3)
  (M)erge, keep (l)ocal or keep (r)emote? m
   subrepository sources for s differ
  use (l)ocal source (2) or (r)emote source (3)? l
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id -n
  2+
  $ cd s
  $ svnversion
  2M
  $ cd ..
  $ hg update --clean tip
  U    *s/alpha (glob)
  
  Fetching external item into '*s/externals'* (glob)
  Checked out external at revision 1.
  
  Checked out revision 3.
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Sticky subrepository, revision updates
  $ hg id -n
  2
  $ cd s
  $ svnversion
  3
  $ cd ..
  $ cd s
  $ svn update -qr 1
  $ cd ..
  $ hg update 1
   subrepository s diverged (local revision: 3, remote revision: 2)
  (M)erge, keep (l)ocal or keep (r)emote? m
   subrepository sources for s differ (in checked out version)
  use (l)ocal source (1) or (r)emote source (2)? l
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id -n
  1+
  $ cd s
  $ svnversion
  1
  $ cd ..

Sticky subrepository, file changes and revision updates
  $ touch s/f1
  $ cd s
  $ svn add f1
  A         f1
  $ svnversion
  1M
  $ cd ..
  $ hg id -n
  1+
  $ hg update tip
   subrepository s diverged (local revision: 3, remote revision: 3)
  (M)erge, keep (l)ocal or keep (r)emote? m
   subrepository sources for s differ
  use (l)ocal source (1) or (r)emote source (3)? l
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id -n
  2+
  $ cd s
  $ svnversion
  1M
  $ cd ..

Sticky repository, update --clean
  $ hg update --clean tip | grep -v 's[/\]externals[/\]other'
  U    *s/alpha (glob)
   U   *s (glob)
  
  Fetching external item into '*s/externals'* (glob)
  Checked out external at revision 1.
  
  Checked out revision 3.
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id -n
  2
  $ cd s
  $ svnversion
  3
  $ cd ..

Test subrepo already at intended revision:
  $ cd s
  $ svn update -qr 2
  $ cd ..
  $ hg update 1
   subrepository s diverged (local revision: 3, remote revision: 2)
  (M)erge, keep (l)ocal or keep (r)emote? m
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg id -n
  1+
  $ cd s
  $ svnversion
  2
  $ cd ..

Test case where subversion would fail to update the subrepo because there
are unknown directories being replaced by tracked ones (happens with rebase).

  $ cd "$WCROOT/src"
  $ mkdir dir
  $ echo epsilon.py > dir/epsilon.py
  $ svn add dir
  A         dir
  A         dir/epsilon.py (glob)
  $ svn ci -qm 'Add dir/epsilon.py'
  $ cd ../..
  $ hg init rebaserepo
  $ cd rebaserepo
  $ svn co -r5 --quiet "$SVNREPOURL"/src s
  $ echo "s =        [svn]       $SVNREPOURL/src" >> .hgsub
  $ hg add .hgsub
  $ hg ci -m addsub
  $ echo a > a
  $ hg add .
  adding a
  $ hg ci -m adda
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ svn up -qr6 s
  $ hg ci -m updatesub
  created new head
  $ echo pyc > s/dir/epsilon.pyc
  $ hg up 1
  D    *s/dir (glob)
  
  Fetching external item into '*s/externals'* (glob)
  Checked out external at revision 1.
  
  Checked out revision 5.
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg up -q 2

Modify one of the externals to point to a different path so we can
test having obstructions when switching branches on checkout:
  $ hg checkout tip
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "obstruct =        [svn]       $SVNREPOURL/externals" >> .hgsub
  $ svn co -r5 --quiet "$SVNREPOURL"/externals obstruct
  $ hg commit -m 'Start making obstructed working copy'
  $ hg book other
  $ hg co -r 'p1(tip)'
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (leaving bookmark other)
  $ echo "obstruct =        [svn]       $SVNREPOURL/src" >> .hgsub
  $ svn co -r5 --quiet "$SVNREPOURL"/src obstruct
  $ hg commit -m 'Other branch which will be obstructed'
  created new head

Switching back to the head where we have another path mapped to the
same subrepo should work if the subrepo is clean.
  $ hg co other
  A    *obstruct/other (glob)
  Checked out revision 1.
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (activating bookmark other)

This is surprising, but is also correct based on the current code:
  $ echo "updating should (maybe) fail" > obstruct/other
  $ hg co tip
  abort: uncommitted changes
  (commit or update --clean to discard changes)
  [255]

Point to a Subversion branch which has since been deleted and recreated
First, create that condition in the repository.

  $ hg ci --subrepos -m cleanup | filter_svn_output
  committing subrepository obstruct
  Sending        obstruct/other (glob)
  Committed revision 7.
  At revision 7.
  $ svn mkdir -qm "baseline" $SVNREPOURL/trunk
  $ svn copy -qm "initial branch" $SVNREPOURL/trunk $SVNREPOURL/branch
  $ svn co --quiet "$SVNREPOURL"/branch tempwc
  $ cd tempwc
  $ echo "something old" > somethingold
  $ svn add somethingold
  A         somethingold
  $ svn ci -qm 'Something old'
  $ svn rm -qm "remove branch" $SVNREPOURL/branch
  $ svn copy -qm "recreate branch" $SVNREPOURL/trunk $SVNREPOURL/branch
  $ svn up -q
  $ echo "something new" > somethingnew
  $ svn add somethingnew
  A         somethingnew
  $ svn ci -qm 'Something new'
  $ cd ..
  $ rm -rf tempwc
  $ svn co "$SVNREPOURL/branch"@10 recreated
  A    recreated/somethingold (glob)
  Checked out revision 10.
  $ echo "recreated =        [svn]       $SVNREPOURL/branch" >> .hgsub
  $ hg ci -m addsub
  $ cd recreated
  $ svn up -q
  $ cd ..
  $ hg ci -m updatesub
  $ hg up -r-2
  D    *recreated/somethingnew (glob)
  A    *recreated/somethingold (glob)
  Checked out revision 10.
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (leaving bookmark other)
  $ test -f recreated/somethingold

Test archive

  $ hg archive -S ../archive-all --debug --config progress.debug=true
  archiving: 0/2 files (0.00%)
  archiving: .hgsub 1/2 files (50.00%)
  archiving: .hgsubstate 2/2 files (100.00%)
  archiving (obstruct): 0/1 files (0.00%)
  archiving (obstruct): 1/1 files (100.00%)
  archiving (recreated): 0/1 files (0.00%)
  archiving (recreated): 1/1 files (100.00%)
  archiving (s): 0/2 files (0.00%)
  archiving (s): 1/2 files (50.00%)
  archiving (s): 2/2 files (100.00%)

  $ hg archive -S ../archive-exclude --debug --config progress.debug=true -X **old
  archiving: 0/2 files (0.00%)
  archiving: .hgsub 1/2 files (50.00%)
  archiving: .hgsubstate 2/2 files (100.00%)
  archiving (obstruct): 0/1 files (0.00%)
  archiving (obstruct): 1/1 files (100.00%)
  archiving (recreated): 0 files
  archiving (s): 0/2 files (0.00%)
  archiving (s): 1/2 files (50.00%)
  archiving (s): 2/2 files (100.00%)
  $ find ../archive-exclude | sort
  ../archive-exclude
  ../archive-exclude/.hg_archival.txt
  ../archive-exclude/.hgsub
  ../archive-exclude/.hgsubstate
  ../archive-exclude/obstruct
  ../archive-exclude/obstruct/other
  ../archive-exclude/s
  ../archive-exclude/s/alpha
  ../archive-exclude/s/dir
  ../archive-exclude/s/dir/epsilon.py

Test forgetting files, not implemented in svn subrepo, used to
traceback

#if no-windows
  $ hg forget 'notafile*'
  notafile*: No such file or directory
  [1]
#else
  $ hg forget 'notafile'
  notafile: * (glob)
  [1]
#endif

Test a subrepo referencing a just moved svn path. Last commit rev will
be different from the revision, and the path will be different as
well.

  $ cd "$WCROOT"
  $ svn up > /dev/null
  $ mkdir trunk/subdir branches
  $ echo a > trunk/subdir/a
  $ svn add trunk/subdir branches
  A         trunk/subdir (glob)
  A         trunk/subdir/a (glob)
  A         branches
  $ svn ci -qm addsubdir
  $ svn cp -qm branchtrunk $SVNREPOURL/trunk $SVNREPOURL/branches/somebranch
  $ cd ..

  $ hg init repo2
  $ cd repo2
  $ svn co $SVNREPOURL/branches/somebranch/subdir
  A    subdir/a (glob)
  Checked out revision 15.
  $ echo "subdir = [svn] $SVNREPOURL/branches/somebranch/subdir" > .hgsub
  $ hg add .hgsub
  $ hg ci -m addsub
  $ hg up null
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg up
  A    *subdir/a (glob)
  Checked out revision 15.
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ..

Test sanitizing ".hg/hgrc" in subrepo

  $ cd sub/t
  $ hg update -q -C tip
  $ cd s
  $ mkdir .hg
  $ echo '.hg/hgrc in svn repo' > .hg/hgrc
  $ mkdir -p sub/.hg
  $ echo 'sub/.hg/hgrc in svn repo' > sub/.hg/hgrc
  $ svn add .hg sub
  A         .hg
  A         .hg/hgrc (glob)
  A         sub
  A         sub/.hg (glob)
  A         sub/.hg/hgrc (glob)
  $ svn ci -qm 'add .hg/hgrc to be sanitized at hg update'
  $ svn up -q
  $ cd ..
  $ hg commit -S -m 'commit with svn revision including .hg/hgrc'
  $ grep ' s$' .hgsubstate
  16 s
  $ cd ..

  $ hg -R tc pull -u -q 2>&1 | sort
  warning: removing potentially hostile 'hgrc' in '$TESTTMP/sub/tc/s/.hg' (glob)
  warning: removing potentially hostile 'hgrc' in '$TESTTMP/sub/tc/s/sub/.hg' (glob)
  $ cd tc
  $ grep ' s$' .hgsubstate
  16 s
  $ test -f s/.hg/hgrc
  [1]
  $ test -f s/sub/.hg/hgrc
  [1]

Test that sanitizing is omitted in meta data area:

  $ mkdir s/.svn/.hg
  $ echo '.hg/hgrc in svn metadata area' > s/.svn/.hg/hgrc
  $ hg update -q -C '.^1'

  $ cd ../..