view tests/test-push-warn.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.

  $ cat << EOF >> $HGRCPATH
  > [experimental]
  > # drop me once bundle2 is the default,
  > # added to get test change early.
  > bundle2-exp = True
  > EOF
  $ hg init a
  $ cd a
  $ echo foo > t1
  $ hg add t1
  $ hg commit -m "1"

  $ cd ..
  $ hg clone a b
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd a
  $ echo foo > t2
  $ hg add t2
  $ hg commit -m "2"

  $ cd ../b
  $ echo foo > t3
  $ hg add t3
  $ hg commit -m "3"

Specifying a revset that evaluates to null will abort

  $ hg push -r '0 & 1' ../a
  pushing to ../a
  abort: specified revisions evaluate to an empty set
  (use different revision arguments)
  [255]

  $ hg push ../a
  pushing to ../a
  searching for changes
  remote has heads on branch 'default' that are not known locally: 1c9246a22a0a
  abort: push creates new remote head 1e108cc5548c!
  (pull and merge or see "hg help push" for details about pushing new heads)
  [255]

  $ hg push --debug ../a
  pushing to ../a
  query 1; heads
  searching for changes
  taking quick initial sample
  query 2; still undecided: 1, sample size is: 1
  2 total queries
  listing keys for "phases"
  checking for updated bookmarks
  listing keys for "bookmarks"
  listing keys for "bookmarks"
  remote has heads on branch 'default' that are not known locally: 1c9246a22a0a
  new remote heads on branch 'default':
   1e108cc5548c
  abort: push creates new remote head 1e108cc5548c!
  (pull and merge or see "hg help push" for details about pushing new heads)
  [255]

  $ hg pull ../a
  pulling from ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg push ../a
  pushing to ../a
  searching for changes
  abort: push creates new remote head 1e108cc5548c!
  (merge or see "hg help push" for details about pushing new heads)
  [255]

  $ hg merge
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg commit -m "4"
  $ hg push ../a
  pushing to ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 1 changes to 1 files

  $ cd ..

  $ hg init c
  $ cd c
  $ for i in 0 1 2; do
  >     echo $i >> foo
  >     hg ci -Am $i
  > done
  adding foo
  $ cd ..

  $ hg clone c d
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd d
  $ for i in 0 1; do
  >    hg co -C $i
  >    echo d-$i >> foo
  >    hg ci -m d-$i
  > done
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  created new head
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  created new head

  $ HGMERGE=true hg merge 3
  merging foo
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg ci -m c-d

  $ hg push ../c
  pushing to ../c
  searching for changes
  abort: push creates new remote head 6346d66eb9f5!
  (merge or see "hg help push" for details about pushing new heads)
  [255]

  $ hg push -r 2 ../c
  pushing to ../c
  searching for changes
  no changes found
  [1]

  $ hg push -r 3 ../c
  pushing to ../c
  searching for changes
  abort: push creates new remote head a5dda829a167!
  (merge or see "hg help push" for details about pushing new heads)
  [255]

  $ hg push -v -r 3 -r 4 ../c
  pushing to ../c
  searching for changes
  new remote heads on branch 'default':
   a5dda829a167
   ee8fbc7a0295
  abort: push creates new remote head a5dda829a167!
  (merge or see "hg help push" for details about pushing new heads)
  [255]

  $ hg push -v -f -r 3 -r 4 ../c
  pushing to ../c
  searching for changes
  2 changesets found
  uncompressed size of bundle content:
       348 (changelog)
       326 (manifests)
       253  foo
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files (+2 heads)

  $ hg push -r 5 ../c
  pushing to ../c
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (-1 heads)

  $ hg in ../c
  comparing with ../c
  searching for changes
  no changes found
  [1]


Issue450: push -r warns about remote head creation even if no heads
will be created

  $ hg init ../e
  $ hg push -r 0 ../e
  pushing to ../e
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files

  $ hg push -r 1 ../e
  pushing to ../e
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files

  $ cd ..


Issue736: named branches are not considered for detection of
unmerged heads in "hg push"

  $ hg init f
  $ cd f
  $ hg -q branch a
  $ echo 0 > foo
  $ hg -q ci -Am 0
  $ echo 1 > foo
  $ hg -q ci -m 1
  $ hg -q up 0
  $ echo 2 > foo
  $ hg -q ci -m 2
  $ hg -q up 0
  $ hg -q branch b
  $ echo 3 > foo
  $ hg -q ci -m 3
  $ cd ..

  $ hg -q clone f g
  $ cd g

Push on existing branch and new branch:

  $ hg -q up 1
  $ echo 4 > foo
  $ hg -q ci -m 4
  $ hg -q up 0
  $ echo 5 > foo
  $ hg -q branch c
  $ hg -q ci -m 5

  $ hg push ../f
  pushing to ../f
  searching for changes
  abort: push creates new remote branches: c!
  (use 'hg push --new-branch' to create new remote branches)
  [255]

  $ hg push -r 4 -r 5 ../f
  pushing to ../f
  searching for changes
  abort: push creates new remote branches: c!
  (use 'hg push --new-branch' to create new remote branches)
  [255]


Multiple new branches:

  $ hg -q branch d
  $ echo 6 > foo
  $ hg -q ci -m 6

  $ hg push ../f
  pushing to ../f
  searching for changes
  abort: push creates new remote branches: c, d!
  (use 'hg push --new-branch' to create new remote branches)
  [255]

  $ hg push -r 4 -r 6 ../f
  pushing to ../f
  searching for changes
  abort: push creates new remote branches: c, d!
  (use 'hg push --new-branch' to create new remote branches)
  [255]

  $ cd ../g


Fail on multiple head push:

  $ hg -q up 1
  $ echo 7 > foo
  $ hg -q ci -m 7

  $ hg push -r 4 -r 7 ../f
  pushing to ../f
  searching for changes
  abort: push creates new remote head 0b715ef6ff8f on branch 'a'!
  (merge or see "hg help push" for details about pushing new heads)
  [255]

Push replacement head on existing branches:

  $ hg -q up 3
  $ echo 8 > foo
  $ hg -q ci -m 8

  $ hg push -r 7 -r 8 ../f
  pushing to ../f
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files


Merge of branch a to other branch b followed by unrelated push
on branch a:

  $ hg -q up 7
  $ HGMERGE=true hg -q merge 8
  $ hg -q ci -m 9
  $ hg -q up 8
  $ echo 10 > foo
  $ hg -q ci -m 10

  $ hg push -r 9 ../f
  pushing to ../f
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (-1 heads)

  $ hg push -r 10 ../f
  pushing to ../f
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)


Cheating the counting algorithm:

  $ hg -q up 9
  $ HGMERGE=true hg -q merge 2
  $ hg -q ci -m 11
  $ hg -q up 1
  $ echo 12 > foo
  $ hg -q ci -m 12

  $ hg push -r 11 -r 12 ../f
  pushing to ../f
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files


Failed push of new named branch:

  $ echo 12 > foo
  $ hg -q ci -m 12a
  [1]
  $ hg -q up 11
  $ echo 13 > foo
  $ hg -q branch e
  $ hg -q ci -m 13d

  $ hg push -r 12 -r 13 ../f
  pushing to ../f
  searching for changes
  abort: push creates new remote branches: e!
  (use 'hg push --new-branch' to create new remote branches)
  [255]


Using --new-branch to push new named branch:

  $ hg push --new-branch -r 12 -r 13 ../f
  pushing to ../f
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files

Pushing multi headed new branch:

  $ echo 14 > foo
  $ hg -q branch f
  $ hg -q ci -m 14
  $ echo 15 > foo
  $ hg -q ci -m 15
  $ hg -q up 14
  $ echo 16 > foo
  $ hg -q ci -m 16
  $ hg push --branch f --new-branch ../f
  pushing to ../f
  searching for changes
  abort: push creates new branch 'f' with multiple heads
  (merge or see "hg help push" for details about pushing new heads)
  [255]
  $ hg push --branch f --new-branch --force ../f
  pushing to ../f
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files (+1 heads)

Checking prepush logic does not allow silently pushing
multiple new heads but also doesn't report too many heads:

  $ cd ..
  $ hg init h
  $ echo init > h/init
  $ hg -R h ci -Am init
  adding init
  $ echo a > h/a
  $ hg -R h ci -Am a
  adding a
  $ hg clone h i
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R h up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo b > h/b
  $ hg -R h ci -Am b
  adding b
  created new head
  $ hg -R i up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo c > i/c
  $ hg -R i ci -Am c
  adding c
  created new head

  $ for i in `python $TESTDIR/seq.py 3`; do hg -R h up -q 0; echo $i > h/b; hg -R h ci -qAm$i; done

  $ hg -R i push h
  pushing to h
  searching for changes
  remote has heads on branch 'default' that are not known locally: 534543e22c29 764f8ec07b96 afe7cc7679f5 ce4212fc8847
  abort: push creates new remote head 97bd0c84d346!
  (pull and merge or see "hg help push" for details about pushing new heads)
  [255]
  $ hg -R h up -q 0; echo x > h/b; hg -R h ci -qAmx
  $ hg -R i push h
  pushing to h
  searching for changes
  remote has heads on branch 'default' that are not known locally: 18ddb72c4590 534543e22c29 764f8ec07b96 afe7cc7679f5 and 1 others
  abort: push creates new remote head 97bd0c84d346!
  (pull and merge or see "hg help push" for details about pushing new heads)
  [255]
  $ hg -R i push h -v
  pushing to h
  searching for changes
  remote has heads on branch 'default' that are not known locally: 18ddb72c4590 534543e22c29 764f8ec07b96 afe7cc7679f5 ce4212fc8847
  new remote heads on branch 'default':
   97bd0c84d346
  abort: push creates new remote head 97bd0c84d346!
  (pull and merge or see "hg help push" for details about pushing new heads)
  [255]


Check prepush logic with merged branches:

  $ hg init j
  $ hg -R j branch a
  marked working directory as branch a
  (branches are permanent and global, did you want a bookmark?)
  $ echo init > j/foo
  $ hg -R j ci -Am init
  adding foo
  $ hg clone j k
  updating to branch a
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a1 > j/foo
  $ hg -R j ci -m a1
  $ hg -R k branch b
  marked working directory as branch b
  $ echo b > k/foo
  $ hg -R k ci -m b
  $ hg -R k up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg -R k merge b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg -R k ci -m merge

  $ hg -R k push -r a j
  pushing to j
  searching for changes
  abort: push creates new remote branches: b!
  (use 'hg push --new-branch' to create new remote branches)
  [255]


Prepush -r should not allow you to sneak in new heads:

  $ hg init l
  $ cd l
  $ echo a >> foo
  $ hg -q add foo
  $ hg -q branch a
  $ hg -q ci -ma
  $ hg -q up null
  $ echo a >> foo
  $ hg -q add foo
  $ hg -q branch b
  $ hg -q ci -mb
  $ cd ..
  $ hg -q clone l m -u a
  $ cd m
  $ hg -q merge b
  $ hg -q ci -mmb
  $ hg -q up 0
  $ echo a >> foo
  $ hg -q ci -ma2
  $ hg -q up 2
  $ echo a >> foo
  $ hg -q branch -f b
  $ hg -q ci -mb2
  $ hg -q merge 3
  $ hg -q ci -mma

  $ hg push ../l -b b
  pushing to ../l
  searching for changes
  abort: push creates new remote head 451211cc22b0 on branch 'a'!
  (merge or see "hg help push" for details about pushing new heads)
  [255]

  $ cd ..


Check prepush with new branch head on former topo non-head:

  $ hg init n
  $ cd n
  $ hg branch A
  marked working directory as branch A
  (branches are permanent and global, did you want a bookmark?)
  $ echo a >a
  $ hg ci -Ama
  adding a
  $ hg branch B
  marked working directory as branch B
  $ echo b >b
  $ hg ci -Amb
  adding b

b is now branch head of B, and a topological head
a is now branch head of A, but not a topological head

  $ hg clone . inner
  updating to branch B
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd inner
  $ hg up B
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b1 >b1
  $ hg ci -Amb1
  adding b1

in the clone b1 is now the head of B

  $ cd ..
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo a2 >a2
  $ hg ci -Ama2
  adding a2

a2 is now the new branch head of A, and a new topological head
it replaces a former inner branch head, so it should at most warn about
A, not B

glog of local:

  $ hg log -G --template "{rev}: {branches} {desc}\n"
  @  2: A a2
  |
  | o  1: B b
  |/
  o  0: A a
  
glog of remote:

  $ hg log -G -R inner --template "{rev}: {branches} {desc}\n"
  @  2: B b1
  |
  o  1: B b
  |
  o  0: A a
  
outgoing:

  $ hg out inner --template "{rev}: {branches} {desc}\n"
  comparing with inner
  searching for changes
  2: A a2

  $ hg push inner
  pushing to inner
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)

  $ cd ..


Check prepush with new branch head on former topo head:

  $ hg init o
  $ cd o
  $ hg branch A
  marked working directory as branch A
  (branches are permanent and global, did you want a bookmark?)
  $ echo a >a
  $ hg ci -Ama
  adding a
  $ hg branch B
  marked working directory as branch B
  $ echo b >b
  $ hg ci -Amb
  adding b

b is now branch head of B, and a topological head

  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo a1 >a1
  $ hg ci -Ama1
  adding a1

a1 is now branch head of A, and a topological head

  $ hg clone . inner
  updating to branch A
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd inner
  $ hg up B
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo b1 >b1
  $ hg ci -Amb1
  adding b1

in the clone b1 is now the head of B

  $ cd ..
  $ echo a2 >a2
  $ hg ci -Ama2
  adding a2

a2 is now the new branch head of A, and a topological head
it replaces a former topological and branch head, so this should not warn

glog of local:

  $ hg log -G --template "{rev}: {branches} {desc}\n"
  @  3: A a2
  |
  o  2: A a1
  |
  | o  1: B b
  |/
  o  0: A a
  
glog of remote:

  $ hg log -G -R inner --template "{rev}: {branches} {desc}\n"
  @  3: B b1
  |
  | o  2: A a1
  | |
  o |  1: B b
  |/
  o  0: A a
  
outgoing:

  $ hg out inner --template "{rev}: {branches} {desc}\n"
  comparing with inner
  searching for changes
  3: A a2

  $ hg push inner
  pushing to inner
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files

  $ cd ..


Check prepush with new branch head and new child of former branch head
but child is on different branch:

  $ hg init p
  $ cd p
  $ hg branch A
  marked working directory as branch A
  (branches are permanent and global, did you want a bookmark?)
  $ echo a0 >a
  $ hg ci -Ama0
  adding a
  $ echo a1 >a
  $ hg ci -ma1
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg branch B
  marked working directory as branch B
  $ echo b0 >b
  $ hg ci -Amb0
  adding b
  $ echo b1 >b
  $ hg ci -mb1

  $ hg clone . inner
  updating to branch B
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg up A
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg branch -f B
  marked working directory as branch B
  $ echo a3 >a
  $ hg ci -ma3
  created new head
  $ hg up 3
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg branch -f A
  marked working directory as branch A
  $ echo b3 >b
  $ hg ci -mb3
  created new head

glog of local:

  $ hg log -G --template "{rev}: {branches} {desc}\n"
  @  5: A b3
  |
  | o  4: B a3
  | |
  o |  3: B b1
  | |
  o |  2: B b0
   /
  o  1: A a1
  |
  o  0: A a0
  
glog of remote:

  $ hg log -G -R inner --template "{rev}: {branches} {desc}\n"
  @  3: B b1
  |
  o  2: B b0
  
  o  1: A a1
  |
  o  0: A a0
  
outgoing:

  $ hg out inner --template "{rev}: {branches} {desc}\n"
  comparing with inner
  searching for changes
  4: B a3
  5: A b3

  $ hg push inner
  pushing to inner
  searching for changes
  abort: push creates new remote head 7d0f4fb6cf04 on branch 'A'!
  (merge or see "hg help push" for details about pushing new heads)
  [255]

  $ hg push inner -r4 -r5
  pushing to inner
  searching for changes
  abort: push creates new remote head 7d0f4fb6cf04 on branch 'A'!
  (merge or see "hg help push" for details about pushing new heads)
  [255]

  $ hg in inner
  comparing with inner
  searching for changes
  no changes found
  [1]

  $ cd ..