view tests/test-rebase-obsolete.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.

==========================
Test rebase with obsolete
==========================

Enable obsolete

  $ cat >> $HGRCPATH << EOF
  > [ui]
  > logtemplate= {rev}:{node|short} {desc|firstline}
  > [experimental]
  > evolution=createmarkers,allowunstable
  > [phases]
  > publish=False
  > [extensions]'
  > rebase=
  > EOF

Setup rebase canonical repo

  $ hg init base
  $ cd base
  $ hg unbundle "$TESTDIR/bundles/rebase.hg"
  adding changesets
  adding manifests
  adding file changes
  added 8 changesets with 7 changes to 7 files (+2 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up tip
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log -G
  @  7:02de42196ebe H
  |
  | o  6:eea13746799a G
  |/|
  o |  5:24b6387c8c8c F
  | |
  | o  4:9520eea781bc E
  |/
  | o  3:32af7686d403 D
  | |
  | o  2:5fddd98957c8 C
  | |
  | o  1:42ccdea3bb16 B
  |/
  o  0:cd010b8cd998 A
  
  $ cd ..

simple rebase
---------------------------------

  $ hg clone base simple
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd simple
  $ hg up 32af7686d403
  3 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg rebase -d eea13746799a
  rebasing 1:42ccdea3bb16 "B"
  rebasing 2:5fddd98957c8 "C"
  rebasing 3:32af7686d403 "D"
  $ hg log -G
  @  10:8eeb3c33ad33 D
  |
  o  9:2327fea05063 C
  |
  o  8:e4e5be0395b2 B
  |
  | o  7:02de42196ebe H
  | |
  o |  6:eea13746799a G
  |\|
  | o  5:24b6387c8c8c F
  | |
  o |  4:9520eea781bc E
  |/
  o  0:cd010b8cd998 A
  
  $ hg log --hidden -G
  @  10:8eeb3c33ad33 D
  |
  o  9:2327fea05063 C
  |
  o  8:e4e5be0395b2 B
  |
  | o  7:02de42196ebe H
  | |
  o |  6:eea13746799a G
  |\|
  | o  5:24b6387c8c8c F
  | |
  o |  4:9520eea781bc E
  |/
  | x  3:32af7686d403 D
  | |
  | x  2:5fddd98957c8 C
  | |
  | x  1:42ccdea3bb16 B
  |/
  o  0:cd010b8cd998 A
  
  $ hg debugobsolete
  42ccdea3bb16d28e1848c95fe2e44c000f3f21b1 e4e5be0395b2cbd471ed22a26b1b6a1a0658a794 0 (*) {'user': 'test'} (glob)
  5fddd98957c8a54a4d436dfe1da9d87f21a1b97b 2327fea05063f39961b14cb69435a9898dc9a245 0 (*) {'user': 'test'} (glob)
  32af7686d403cf45b5d95f2d70cebea587ac806a 8eeb3c33ad33d452c89e5dcf611c347f978fb42b 0 (*) {'user': 'test'} (glob)


  $ cd ..

empty changeset
---------------------------------

  $ hg clone base empty
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd empty
  $ hg up eea13746799a
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

We make a copy of both the first changeset in the rebased and some other in the
set.

  $ hg graft 42ccdea3bb16 32af7686d403
  grafting 1:42ccdea3bb16 "B"
  grafting 3:32af7686d403 "D"
  $ hg rebase  -s 42ccdea3bb16 -d .
  rebasing 1:42ccdea3bb16 "B"
  note: rebase of 1:42ccdea3bb16 created no changes to commit
  rebasing 2:5fddd98957c8 "C"
  rebasing 3:32af7686d403 "D"
  note: rebase of 3:32af7686d403 created no changes to commit
  $ hg log -G
  o  10:5ae4c968c6ac C
  |
  @  9:08483444fef9 D
  |
  o  8:8877864f1edb B
  |
  | o  7:02de42196ebe H
  | |
  o |  6:eea13746799a G
  |\|
  | o  5:24b6387c8c8c F
  | |
  o |  4:9520eea781bc E
  |/
  o  0:cd010b8cd998 A
  
  $ hg log --hidden -G
  o  10:5ae4c968c6ac C
  |
  @  9:08483444fef9 D
  |
  o  8:8877864f1edb B
  |
  | o  7:02de42196ebe H
  | |
  o |  6:eea13746799a G
  |\|
  | o  5:24b6387c8c8c F
  | |
  o |  4:9520eea781bc E
  |/
  | x  3:32af7686d403 D
  | |
  | x  2:5fddd98957c8 C
  | |
  | x  1:42ccdea3bb16 B
  |/
  o  0:cd010b8cd998 A
  
  $ hg debugobsolete
  42ccdea3bb16d28e1848c95fe2e44c000f3f21b1 0 {cd010b8cd998f3981a5a8115f94f8da4ab506089} (*) {'user': 'test'} (glob)
  5fddd98957c8a54a4d436dfe1da9d87f21a1b97b 5ae4c968c6aca831df823664e706c9d4aa34473d 0 (*) {'user': 'test'} (glob)
  32af7686d403cf45b5d95f2d70cebea587ac806a 0 {5fddd98957c8a54a4d436dfe1da9d87f21a1b97b} (*) {'user': 'test'} (glob)


More complex case were part of the rebase set were already rebased

  $ hg rebase --rev 'desc(D)' --dest 'desc(H)'
  rebasing 9:08483444fef9 "D"
  $ hg debugobsolete
  42ccdea3bb16d28e1848c95fe2e44c000f3f21b1 0 {cd010b8cd998f3981a5a8115f94f8da4ab506089} (*) {'user': 'test'} (glob)
  5fddd98957c8a54a4d436dfe1da9d87f21a1b97b 5ae4c968c6aca831df823664e706c9d4aa34473d 0 (*) {'user': 'test'} (glob)
  32af7686d403cf45b5d95f2d70cebea587ac806a 0 {5fddd98957c8a54a4d436dfe1da9d87f21a1b97b} (*) {'user': 'test'} (glob)
  08483444fef91d6224f6655ee586a65d263ad34c 4596109a6a4328c398bde3a4a3b6737cfade3003 0 (*) {'user': 'test'} (glob)
  $ hg log -G
  @  11:4596109a6a43 D
  |
  | o  10:5ae4c968c6ac C
  | |
  | x  9:08483444fef9 D
  | |
  | o  8:8877864f1edb B
  | |
  o |  7:02de42196ebe H
  | |
  | o  6:eea13746799a G
  |/|
  o |  5:24b6387c8c8c F
  | |
  | o  4:9520eea781bc E
  |/
  o  0:cd010b8cd998 A
  
  $ hg rebase --source 'desc(B)' --dest 'tip' --config experimental.rebaseskipobsolete=True
  rebasing 8:8877864f1edb "B"
  note: not rebasing 9:08483444fef9 "D", already in destination as 11:4596109a6a43 "D"
  rebasing 10:5ae4c968c6ac "C"
  $ hg debugobsolete
  42ccdea3bb16d28e1848c95fe2e44c000f3f21b1 0 {cd010b8cd998f3981a5a8115f94f8da4ab506089} (*) {'user': 'test'} (glob)
  5fddd98957c8a54a4d436dfe1da9d87f21a1b97b 5ae4c968c6aca831df823664e706c9d4aa34473d 0 (*) {'user': 'test'} (glob)
  32af7686d403cf45b5d95f2d70cebea587ac806a 0 {5fddd98957c8a54a4d436dfe1da9d87f21a1b97b} (*) {'user': 'test'} (glob)
  08483444fef91d6224f6655ee586a65d263ad34c 4596109a6a4328c398bde3a4a3b6737cfade3003 0 (*) {'user': 'test'} (glob)
  8877864f1edb05d0e07dc4ba77b67a80a7b86672 462a34d07e599b87ea08676a449373fe4e2e1347 0 (*) {'user': 'test'} (glob)
  5ae4c968c6aca831df823664e706c9d4aa34473d 98f6af4ee9539e14da4465128f894c274900b6e5 0 (*) {'user': 'test'} (glob)
  $ hg log --rev 'divergent()'
  $ hg log -G
  o  13:98f6af4ee953 C
  |
  o  12:462a34d07e59 B
  |
  @  11:4596109a6a43 D
  |
  o  7:02de42196ebe H
  |
  | o  6:eea13746799a G
  |/|
  o |  5:24b6387c8c8c F
  | |
  | o  4:9520eea781bc E
  |/
  o  0:cd010b8cd998 A
  
  $ hg log --style default --debug -r 4596109a6a4328c398bde3a4a3b6737cfade3003
  changeset:   11:4596109a6a4328c398bde3a4a3b6737cfade3003
  phase:       draft
  parent:      7:02de42196ebee42ef284b6780a87cdc96e8eaab6
  parent:      -1:0000000000000000000000000000000000000000
  manifest:    11:a91006e3a02f1edf631f7018e6e5684cf27dd905
  user:        Nicolas Dumazet <[e-mail]>
  date:        Sat Apr 30 15:24:48 2011 +0200
  files+:      D
  extra:       branch=default
  extra:       rebase_source=08483444fef91d6224f6655ee586a65d263ad34c
  extra:       source=32af7686d403cf45b5d95f2d70cebea587ac806a
  description:
  D
  
  
  $ cd ..

collapse rebase
---------------------------------

  $ hg clone base collapse
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd collapse
  $ hg rebase  -s 42ccdea3bb16 -d eea13746799a --collapse
  rebasing 1:42ccdea3bb16 "B"
  note: rebase of 1:42ccdea3bb16 created no changes to commit
  rebasing 2:5fddd98957c8 "C"
  note: rebase of 2:5fddd98957c8 created no changes to commit
  rebasing 3:32af7686d403 "D"
  note: rebase of 3:32af7686d403 created no changes to commit
  $ hg log -G
  o  8:4dc2197e807b Collapsed revision
  |
  | @  7:02de42196ebe H
  | |
  o |  6:eea13746799a G
  |\|
  | o  5:24b6387c8c8c F
  | |
  o |  4:9520eea781bc E
  |/
  o  0:cd010b8cd998 A
  
  $ hg log --hidden -G
  o  8:4dc2197e807b Collapsed revision
  |
  | @  7:02de42196ebe H
  | |
  o |  6:eea13746799a G
  |\|
  | o  5:24b6387c8c8c F
  | |
  o |  4:9520eea781bc E
  |/
  | x  3:32af7686d403 D
  | |
  | x  2:5fddd98957c8 C
  | |
  | x  1:42ccdea3bb16 B
  |/
  o  0:cd010b8cd998 A
  
  $ hg id --debug -r tip
  4dc2197e807bae9817f09905b50ab288be2dbbcf tip
  $ hg debugobsolete
  42ccdea3bb16d28e1848c95fe2e44c000f3f21b1 4dc2197e807bae9817f09905b50ab288be2dbbcf 0 (*) {'user': 'test'} (glob)
  5fddd98957c8a54a4d436dfe1da9d87f21a1b97b 4dc2197e807bae9817f09905b50ab288be2dbbcf 0 (*) {'user': 'test'} (glob)
  32af7686d403cf45b5d95f2d70cebea587ac806a 4dc2197e807bae9817f09905b50ab288be2dbbcf 0 (*) {'user': 'test'} (glob)

  $ cd ..

Rebase set has hidden descendants
---------------------------------

We rebase a changeset which has a hidden changeset. The hidden changeset must
not be rebased.

  $ hg clone base hidden
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd hidden
  $ hg rebase -s 5fddd98957c8 -d eea13746799a
  rebasing 2:5fddd98957c8 "C"
  rebasing 3:32af7686d403 "D"
  $ hg rebase -s 42ccdea3bb16 -d 02de42196ebe
  rebasing 1:42ccdea3bb16 "B"
  $ hg log -G
  o  10:7c6027df6a99 B
  |
  | o  9:cf44d2f5a9f4 D
  | |
  | o  8:e273c5e7d2d2 C
  | |
  @ |  7:02de42196ebe H
  | |
  | o  6:eea13746799a G
  |/|
  o |  5:24b6387c8c8c F
  | |
  | o  4:9520eea781bc E
  |/
  o  0:cd010b8cd998 A
  
  $ hg log --hidden -G
  o  10:7c6027df6a99 B
  |
  | o  9:cf44d2f5a9f4 D
  | |
  | o  8:e273c5e7d2d2 C
  | |
  @ |  7:02de42196ebe H
  | |
  | o  6:eea13746799a G
  |/|
  o |  5:24b6387c8c8c F
  | |
  | o  4:9520eea781bc E
  |/
  | x  3:32af7686d403 D
  | |
  | x  2:5fddd98957c8 C
  | |
  | x  1:42ccdea3bb16 B
  |/
  o  0:cd010b8cd998 A
  
  $ hg debugobsolete
  5fddd98957c8a54a4d436dfe1da9d87f21a1b97b e273c5e7d2d29df783dce9f9eaa3ac4adc69c15d 0 (*) {'user': 'test'} (glob)
  32af7686d403cf45b5d95f2d70cebea587ac806a cf44d2f5a9f4297a62be94cbdd3dff7c7dc54258 0 (*) {'user': 'test'} (glob)
  42ccdea3bb16d28e1848c95fe2e44c000f3f21b1 7c6027df6a99d93f461868e5433f63bde20b6dfb 0 (*) {'user': 'test'} (glob)

Test that rewriting leaving instability behind is allowed
---------------------------------------------------------------------

  $ hg log -r 'children(8)'
  9:cf44d2f5a9f4 D (no-eol)
  $ hg rebase -r 8
  rebasing 8:e273c5e7d2d2 "C"
  $ hg log -G
  o  11:0d8f238b634c C
  |
  o  10:7c6027df6a99 B
  |
  | o  9:cf44d2f5a9f4 D
  | |
  | x  8:e273c5e7d2d2 C
  | |
  @ |  7:02de42196ebe H
  | |
  | o  6:eea13746799a G
  |/|
  o |  5:24b6387c8c8c F
  | |
  | o  4:9520eea781bc E
  |/
  o  0:cd010b8cd998 A
  


Test multiple root handling
------------------------------------

  $ hg rebase --dest 4 --rev '7+11+9'
  rebasing 7:02de42196ebe "H"
  rebasing 9:cf44d2f5a9f4 "D"
  not rebasing ignored 10:7c6027df6a99 "B"
  rebasing 11:0d8f238b634c "C" (tip)
  $ hg log -G
  o  14:1e8370e38cca C
  |
  | o  13:102b4c1d889b D
  | |
  @ |  12:bfe264faf697 H
  |/
  | o  10:7c6027df6a99 B
  | |
  | x  7:02de42196ebe H
  | |
  +---o  6:eea13746799a G
  | |/
  | o  5:24b6387c8c8c F
  | |
  o |  4:9520eea781bc E
  |/
  o  0:cd010b8cd998 A
  
  $ cd ..

test on rebase dropping a merge

(setup)

  $ hg init dropmerge
  $ cd dropmerge
  $ hg unbundle "$TESTDIR/bundles/rebase.hg"
  adding changesets
  adding manifests
  adding file changes
  added 8 changesets with 7 changes to 7 files (+2 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up 3
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg merge 7
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m 'M'
  $ echo I > I
  $ hg add I
  $ hg ci -m I
  $ hg log -G
  @  9:4bde274eefcf I
  |
  o    8:53a6a128b2b7 M
  |\
  | o  7:02de42196ebe H
  | |
  | | o  6:eea13746799a G
  | |/|
  | o |  5:24b6387c8c8c F
  | | |
  | | o  4:9520eea781bc E
  | |/
  o |  3:32af7686d403 D
  | |
  o |  2:5fddd98957c8 C
  | |
  o |  1:42ccdea3bb16 B
  |/
  o  0:cd010b8cd998 A
  
(actual test)

  $ hg rebase --dest 6 --rev '((desc(H) + desc(D))::) - desc(M)'
  rebasing 3:32af7686d403 "D"
  rebasing 7:02de42196ebe "H"
  not rebasing ignored 8:53a6a128b2b7 "M"
  rebasing 9:4bde274eefcf "I" (tip)
  $ hg log -G
  @  12:acd174b7ab39 I
  |
  o  11:6c11a6218c97 H
  |
  | o  10:b5313c85b22e D
  |/
  | o    8:53a6a128b2b7 M
  | |\
  | | x  7:02de42196ebe H
  | | |
  o---+  6:eea13746799a G
  | | |
  | | o  5:24b6387c8c8c F
  | | |
  o---+  4:9520eea781bc E
   / /
  x |  3:32af7686d403 D
  | |
  o |  2:5fddd98957c8 C
  | |
  o |  1:42ccdea3bb16 B
  |/
  o  0:cd010b8cd998 A
  

Test hidden changesets in the rebase set (issue4504)

  $ hg up --hidden 9
  3 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo J > J
  $ hg add J
  $ hg commit -m J
  $ hg debugobsolete `hg log --rev . -T '{node}'`

  $ hg rebase --rev .~1::. --dest 'max(desc(D))' --traceback
  rebasing 9:4bde274eefcf "I"
  rebasing 13:06edfc82198f "J" (tip)
  $ hg log -G
  @  15:5ae8a643467b J
  |
  o  14:9ad579b4a5de I
  |
  | o  12:acd174b7ab39 I
  | |
  | o  11:6c11a6218c97 H
  | |
  o |  10:b5313c85b22e D
  |/
  | o    8:53a6a128b2b7 M
  | |\
  | | x  7:02de42196ebe H
  | | |
  o---+  6:eea13746799a G
  | | |
  | | o  5:24b6387c8c8c F
  | | |
  o---+  4:9520eea781bc E
   / /
  x |  3:32af7686d403 D
  | |
  o |  2:5fddd98957c8 C
  | |
  o |  1:42ccdea3bb16 B
  |/
  o  0:cd010b8cd998 A
  
  $ hg up 14 -C
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo "K" > K
  $ hg add K
  $ hg commit --amend -m "K"
  $ echo "L" > L
  $ hg add L
  $ hg commit -m "L"
  $ hg up '.^'
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo "M" > M
  $ hg add M
  $ hg commit --amend -m "M"
  $ hg log -G
  @  20:bfaedf8eb73b M
  |
  | o  18:97219452e4bd L
  | |
  | x  17:fc37a630c901 K
  |/
  | o  15:5ae8a643467b J
  | |
  | x  14:9ad579b4a5de I
  |/
  | o  12:acd174b7ab39 I
  | |
  | o  11:6c11a6218c97 H
  | |
  o |  10:b5313c85b22e D
  |/
  | o    8:53a6a128b2b7 M
  | |\
  | | x  7:02de42196ebe H
  | | |
  o---+  6:eea13746799a G
  | | |
  | | o  5:24b6387c8c8c F
  | | |
  o---+  4:9520eea781bc E
   / /
  x |  3:32af7686d403 D
  | |
  o |  2:5fddd98957c8 C
  | |
  o |  1:42ccdea3bb16 B
  |/
  o  0:cd010b8cd998 A
  
  $ hg rebase -s 14 -d 18 --config experimental.rebaseskipobsolete=True
  note: not rebasing 14:9ad579b4a5de "I", already in destination as 17:fc37a630c901 "K"
  rebasing 15:5ae8a643467b "J"