view tests/test-http.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 serve

  $ hg init test
  $ cd test
  $ echo foo>foo
  $ mkdir foo.d foo.d/bAr.hg.d foo.d/baR.d.hg
  $ echo foo>foo.d/foo
  $ echo bar>foo.d/bAr.hg.d/BaR
  $ echo bar>foo.d/baR.d.hg/bAR
  $ hg commit -A -m 1
  adding foo
  adding foo.d/bAr.hg.d/BaR
  adding foo.d/baR.d.hg/bAR
  adding foo.d/foo
  $ hg serve -p $HGPORT -d --pid-file=../hg1.pid -E ../error.log
  $ hg --config server.uncompressed=False serve -p $HGPORT1 -d --pid-file=../hg2.pid

Test server address cannot be reused

#if windows
  $ hg serve -p $HGPORT1 2>&1
  abort: cannot start server at ':$HGPORT1': * (glob)
  [255]
#else
  $ hg serve -p $HGPORT1 2>&1
  abort: cannot start server at ':$HGPORT1': Address already in use
  [255]
#endif
  $ cd ..
  $ cat hg1.pid hg2.pid >> $DAEMON_PIDS

clone via stream

  $ hg clone --uncompressed http://localhost:$HGPORT/ copy 2>&1
  streaming all changes
  6 files to transfer, 606 bytes of data
  transferred * bytes in * seconds (*/sec) (glob)
  searching for changes
  no changes found
  updating to branch default
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg verify -R copy
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  4 files, 1 changesets, 4 total revisions

try to clone via stream, should use pull instead

  $ hg clone --uncompressed http://localhost:$HGPORT1/ copy2
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 4 changes to 4 files
  updating to branch default
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved

clone via pull

  $ hg clone http://localhost:$HGPORT1/ copy-pull
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 4 changes to 4 files
  updating to branch default
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg verify -R copy-pull
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  4 files, 1 changesets, 4 total revisions
  $ cd test
  $ echo bar > bar
  $ hg commit -A -d '1 0' -m 2
  adding bar
  $ cd ..

clone over http with --update

  $ hg clone http://localhost:$HGPORT1/ updated --update 0
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 5 changes to 5 files
  updating to branch default
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log -r . -R updated
  changeset:   0:8b6053c928fe
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  $ rm -rf updated

incoming via HTTP

  $ hg clone http://localhost:$HGPORT1/ --rev 0 partial
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 4 changes to 4 files
  updating to branch default
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd partial
  $ touch LOCAL
  $ hg ci -qAm LOCAL
  $ hg incoming http://localhost:$HGPORT1/ --template '{desc}\n'
  comparing with http://localhost:$HGPORT1/
  searching for changes
  2
  $ cd ..

pull

  $ cd copy-pull
  $ echo '[hooks]' >> .hg/hgrc
  $ echo "changegroup = printenv.py changegroup" >> .hg/hgrc
  $ hg pull
  pulling from http://localhost:$HGPORT1/
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  changegroup hook: HG_NODE=5fed3813f7f5e1824344fdc9cf8f63bb662c292d HG_SOURCE=pull HG_TXNID=TXN:* HG_URL=http://localhost:$HGPORT1/ (glob)
  (run 'hg update' to get a working copy)
  $ cd ..

clone from invalid URL

  $ hg clone http://localhost:$HGPORT/bad
  abort: HTTP Error 404: Not Found
  [255]

test http authentication
+ use the same server to test server side streaming preference

  $ cd test
  $ cat << EOT > userpass.py
  > import base64
  > from mercurial.hgweb import common
  > def perform_authentication(hgweb, req, op):
  >     auth = req.env.get('HTTP_AUTHORIZATION')
  >     if not auth:
  >         raise common.ErrorResponse(common.HTTP_UNAUTHORIZED, 'who',
  >                 [('WWW-Authenticate', 'Basic Realm="mercurial"')])
  >     if base64.b64decode(auth.split()[1]).split(':', 1) != ['user', 'pass']:
  >         raise common.ErrorResponse(common.HTTP_FORBIDDEN, 'no')
  > def extsetup():
  >     common.permhooks.insert(0, perform_authentication)
  > EOT
  $ hg --config extensions.x=userpass.py serve -p $HGPORT2 -d --pid-file=pid \
  >    --config server.preferuncompressed=True \
  >    --config web.push_ssl=False --config web.allow_push=* -A ../access.log
  $ cat pid >> $DAEMON_PIDS

  $ cat << EOF > get_pass.py
  > import getpass
  > def newgetpass(arg):
  >   return "pass"
  > getpass.getpass = newgetpass
  > EOF

  $ hg id http://localhost:$HGPORT2/
  abort: http authorization required for http://localhost:$HGPORT2/
  [255]
  $ hg id http://localhost:$HGPORT2/
  abort: http authorization required for http://localhost:$HGPORT2/
  [255]
  $ hg id --config ui.interactive=true --config extensions.getpass=get_pass.py http://user@localhost:$HGPORT2/
  http authorization required for http://localhost:$HGPORT2/
  realm: mercurial
  user: user
  password: 5fed3813f7f5
  $ hg id http://user:pass@localhost:$HGPORT2/
  5fed3813f7f5
  $ echo '[auth]' >> .hg/hgrc
  $ echo 'l.schemes=http' >> .hg/hgrc
  $ echo 'l.prefix=lo' >> .hg/hgrc
  $ echo 'l.username=user' >> .hg/hgrc
  $ echo 'l.password=pass' >> .hg/hgrc
  $ hg id http://localhost:$HGPORT2/
  5fed3813f7f5
  $ hg id http://localhost:$HGPORT2/
  5fed3813f7f5
  $ hg id http://user@localhost:$HGPORT2/
  5fed3813f7f5
  $ hg clone http://user:pass@localhost:$HGPORT2/ dest 2>&1
  streaming all changes
  7 files to transfer, 916 bytes of data
  transferred * bytes in * seconds (*/sec) (glob)
  searching for changes
  no changes found
  updating to branch default
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved
--pull should override server's preferuncompressed
  $ hg clone --pull http://user:pass@localhost:$HGPORT2/ dest-pull 2>&1
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 5 changes to 5 files
  updating to branch default
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg id http://user2@localhost:$HGPORT2/
  abort: http authorization required for http://localhost:$HGPORT2/
  [255]
  $ hg id http://user:pass2@localhost:$HGPORT2/
  abort: HTTP Error 403: no
  [255]

  $ hg -R dest tag -r tip top
  $ hg -R dest push http://user:pass@localhost:$HGPORT2/
  pushing to http://user:***@localhost:$HGPORT2/
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  $ hg rollback -q

  $ cut -c38- ../access.log
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=lookup HTTP/1.1" 200 - x-hgarg-1:key=tip
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=lookup HTTP/1.1" 200 - x-hgarg-1:key=tip
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=lookup HTTP/1.1" 200 - x-hgarg-1:key=tip
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=lookup HTTP/1.1" 200 - x-hgarg-1:key=tip
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=lookup HTTP/1.1" 200 - x-hgarg-1:key=tip
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=lookup HTTP/1.1" 200 - x-hgarg-1:key=tip
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=lookup HTTP/1.1" 200 - x-hgarg-1:key=tip
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=branchmap HTTP/1.1" 200 -
  "GET /?cmd=stream_out HTTP/1.1" 401 -
  "GET /?cmd=stream_out HTTP/1.1" 200 -
  "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D5fed3813f7f5e1824344fdc9cf8f63bb662c292d
  "GET /?cmd=getbundle HTTP/1.1" 200 - x-hgarg-1:bundlecaps=HG20%2Cbundle2%3DHG20%250Achangegroup%253D01%252C02%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps&cg=0&common=5fed3813f7f5e1824344fdc9cf8f63bb662c292d&heads=5fed3813f7f5e1824344fdc9cf8f63bb662c292d&listkeys=phase%2Cbookmarks
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D
  "GET /?cmd=getbundle HTTP/1.1" 401 - x-hgarg-1:bundlecaps=HG20%2Cbundle2%3DHG20%250Achangegroup%253D01%252C02%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps&cg=1&common=0000000000000000000000000000000000000000&heads=5fed3813f7f5e1824344fdc9cf8f63bb662c292d&listkeys=phase%2Cbookmarks
  "GET /?cmd=getbundle HTTP/1.1" 200 - x-hgarg-1:bundlecaps=HG20%2Cbundle2%3DHG20%250Achangegroup%253D01%252C02%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps&cg=1&common=0000000000000000000000000000000000000000&heads=5fed3813f7f5e1824344fdc9cf8f63bb662c292d&listkeys=phase%2Cbookmarks
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=lookup HTTP/1.1" 200 - x-hgarg-1:key=tip
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=lookup HTTP/1.1" 200 - x-hgarg-1:key=tip
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=listkeys HTTP/1.1" 403 - x-hgarg-1:namespace=namespaces
  "GET /?cmd=capabilities HTTP/1.1" 200 -
  "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D7f4e523d01f2cc3765ac8934da3d14db775ff872
  "GET /?cmd=listkeys HTTP/1.1" 401 - x-hgarg-1:namespace=phases
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks
  "GET /?cmd=branchmap HTTP/1.1" 200 -
  "GET /?cmd=branchmap HTTP/1.1" 200 -
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks
  "POST /?cmd=unbundle HTTP/1.1" 200 - x-hgarg-1:heads=666f726365
  "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases

  $ cd ..

clone of serve with repo in root and unserved subrepo (issue2970)

  $ hg --cwd test init sub
  $ echo empty > test/sub/empty
  $ hg --cwd test/sub add empty
  $ hg --cwd test/sub commit -qm 'add empty'
  $ hg --cwd test/sub tag -r 0 something
  $ echo sub = sub > test/.hgsub
  $ hg --cwd test add .hgsub
  $ hg --cwd test commit -qm 'add subrepo'
  $ hg clone http://localhost:$HGPORT noslash-clone
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 7 changes to 7 files
  updating to branch default
  abort: HTTP Error 404: Not Found
  [255]
  $ hg clone http://localhost:$HGPORT/ slash-clone
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 7 changes to 7 files
  updating to branch default
  abort: HTTP Error 404: Not Found
  [255]

check error log

  $ cat error.log