view tests/test-histedit-arguments.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 argument handling and various data parsing
==================================================


Enable extensions used by this test.
  $ cat >>$HGRCPATH <<EOF
  > [extensions]
  > histedit=
  > EOF

Repo setup.
  $ hg init foo
  $ cd foo
  $ echo alpha >> alpha
  $ hg addr
  adding alpha
  $ hg ci -m one
  $ echo alpha >> alpha
  $ hg ci -m two
  $ echo alpha >> alpha
  $ hg ci -m three
  $ echo alpha >> alpha
  $ hg ci -m four
  $ echo alpha >> alpha
  $ hg ci -m five

  $ hg log --style compact --graph
  @  4[tip]   08d98a8350f3   1970-01-01 00:00 +0000   test
  |    five
  |
  o  3   c8e68270e35a   1970-01-01 00:00 +0000   test
  |    four
  |
  o  2   eb57da33312f   1970-01-01 00:00 +0000   test
  |    three
  |
  o  1   579e40513370   1970-01-01 00:00 +0000   test
  |    two
  |
  o  0   6058cbb6cfd7   1970-01-01 00:00 +0000   test
       one
  

histedit --continue/--abort with no existing state
--------------------------------------------------

  $ hg histedit --continue
  abort: no histedit in progress
  [255]
  $ hg histedit --abort
  abort: no histedit in progress
  [255]

Run a dummy edit to make sure we get tip^^ correctly via revsingle.
--------------------------------------------------------------------

  $ HGEDITOR=cat hg histedit "tip^^"
  pick eb57da33312f 2 three
  pick c8e68270e35a 3 four
  pick 08d98a8350f3 4 five
  
  # Edit history between eb57da33312f and 08d98a8350f3
  #
  # Commits are listed from least to most recent
  #
  # Commands:
  #  p, pick = use commit
  #  e, edit = use commit, but stop for amending
  #  f, fold = use commit, but combine it with the one above
  #  r, roll = like fold, but discard this commit's description
  #  d, drop = remove commit from history
  #  m, mess = edit commit message without changing commit content
  #
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

Run on a revision not ancestors of the current working directory.
--------------------------------------------------------------------

  $ hg up 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg histedit -r 4
  abort: 08d98a8350f3 is not an ancestor of working directory
  [255]
  $ hg up --quiet


Test that we pick the minimum of a revrange
---------------------------------------

  $ HGEDITOR=cat hg histedit '2::' --commands - << EOF
  > pick eb57da33312f 2 three
  > pick c8e68270e35a 3 four
  > pick 08d98a8350f3 4 five
  > EOF
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg up --quiet

  $ HGEDITOR=cat hg histedit 'tip:2' --commands - << EOF
  > pick eb57da33312f 2 three
  > pick c8e68270e35a 3 four
  > pick 08d98a8350f3 4 five
  > EOF
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg up --quiet

Test config specified default
-----------------------------

  $ HGEDITOR=cat hg histedit --config "histedit.defaultrev=only(.) - ::eb57da33312f" --commands - << EOF
  > pick c8e68270e35a 3 four
  > pick 08d98a8350f3 4 five
  > EOF
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

Run on a revision not descendants of the initial parent
--------------------------------------------------------------------

Test the message shown for inconsistent histedit state, which may be
created (and forgotten) by Mercurial earlier than 2.7. This emulates
Mercurial earlier than 2.7 by renaming ".hg/histedit-state"
temporarily.

  $ hg log -G -T '{rev} {shortest(node)} {desc}\n' -r 2::
  @  4 08d9 five
  |
  o  3 c8e6 four
  |
  o  2 eb57 three
  |
  $ HGEDITOR=cat hg histedit -r 4 --commands - << EOF
  > edit 08d98a8350f3 4 five
  > EOF
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  reverting alpha
  Make changes as needed, you may commit or record as needed now.
  When you are finished, run hg histedit --continue to resume.
  [1]

  $ mv .hg/histedit-state .hg/histedit-state.back
  $ hg update --quiet --clean 2
  $ echo alpha >> alpha
  $ mv .hg/histedit-state.back .hg/histedit-state

  $ hg histedit --continue
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/foo/.hg/strip-backup/08d98a8350f3-02594089-backup.hg (glob)
  $ hg log -G -T '{rev} {shortest(node)} {desc}\n' -r 2::
  @  4 f5ed five
  |
  | o  3 c8e6 four
  |/
  o  2 eb57 three
  |

  $ hg unbundle -q $TESTTMP/foo/.hg/strip-backup/08d98a8350f3-02594089-backup.hg
  $ hg strip -q -r f5ed --config extensions.strip=
  $ hg up -q 08d98a8350f3

Test that missing revisions are detected
---------------------------------------

  $ HGEDITOR=cat hg histedit "tip^^" --commands - << EOF
  > pick eb57da33312f 2 three
  > pick 08d98a8350f3 4 five
  > EOF
  abort: missing rules for changeset c8e68270e35a
  (do you want to use the drop action?)
  [255]

Test that extra revisions are detected
---------------------------------------

  $ HGEDITOR=cat hg histedit "tip^^" --commands - << EOF
  > pick 6058cbb6cfd7 0 one
  > pick c8e68270e35a 3 four
  > pick 08d98a8350f3 4 five
  > EOF
  abort: may not use changesets other than the ones listed
  [255]

Test malformed line
---------------------------------------

  $ HGEDITOR=cat hg histedit "tip^^" --commands - << EOF
  > pickeb57da33312f2three
  > pick c8e68270e35a 3 four
  > pick 08d98a8350f3 4 five
  > EOF
  abort: malformed line "pickeb57da33312f2three"
  [255]

Test unknown changeset
---------------------------------------

  $ HGEDITOR=cat hg histedit "tip^^" --commands - << EOF
  > pick 0123456789ab 2 three
  > pick c8e68270e35a 3 four
  > pick 08d98a8350f3 4 five
  > EOF
  abort: unknown changeset 0123456789ab listed
  [255]

Test unknown command
---------------------------------------

  $ HGEDITOR=cat hg histedit "tip^^" --commands - << EOF
  > coin eb57da33312f 2 three
  > pick c8e68270e35a 3 four
  > pick 08d98a8350f3 4 five
  > EOF
  abort: unknown action "coin"
  [255]

Test duplicated changeset
---------------------------------------

So one is missing and one appear twice.

  $ HGEDITOR=cat hg histedit "tip^^" --commands - << EOF
  > pick eb57da33312f 2 three
  > pick eb57da33312f 2 three
  > pick 08d98a8350f3 4 five
  > EOF
  abort: duplicated command for changeset eb57da33312f
  [255]

Test short version of command
---------------------------------------

Note: we use varying amounts of white space between command name and changeset
short hash. This tests issue3893.

  $ HGEDITOR=cat hg histedit "tip^^" --commands - << EOF
  > pick eb57da33312f 2 three
  > p    c8e68270e35a 3 four
  > f 08d98a8350f3 4 five
  > EOF
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  reverting alpha
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  four
  ***
  five
  
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: changed alpha
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/foo/.hg/strip-backup/*-backup.hg (glob)

  $ hg update -q 2
  $ echo x > x
  $ hg add x
  $ hg commit -m'x' x
  created new head
  $ hg histedit -r 'heads(all())'
  abort: The specified revisions must have exactly one common root
  [255]

Test that trimming description using multi-byte characters
--------------------------------------------------------------------

  $ python <<EOF
  > fp = open('logfile', 'w')
  > fp.write('12345678901234567890123456789012345678901234567890' +
  >          '12345') # there are 5 more columns for 80 columns
  > 
  > # 2 x 4 = 8 columns, but 3 x 4 = 12 bytes
  > fp.write(u'\u3042\u3044\u3046\u3048'.encode('utf-8'))
  > 
  > fp.close()
  > EOF
  $ echo xx >> x
  $ hg --encoding utf-8 commit --logfile logfile

  $ HGEDITOR=cat hg --encoding utf-8 histedit tip
  pick 3d3ea1f3a10b 5 1234567890123456789012345678901234567890123456789012345\xe3\x81\x82... (esc)
  
  # Edit history between 3d3ea1f3a10b and 3d3ea1f3a10b
  #
  # Commits are listed from least to most recent
  #
  # Commands:
  #  p, pick = use commit
  #  e, edit = use commit, but stop for amending
  #  f, fold = use commit, but combine it with the one above
  #  r, roll = like fold, but discard this commit's description
  #  d, drop = remove commit from history
  #  m, mess = edit commit message without changing commit content
  #
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

Test --continue with --keep

  $ hg strip -q -r . --config extensions.strip=
  $ hg histedit '.^' -q --keep --commands - << EOF
  > edit eb57da33312f 2 three
  > pick f3cfcca30c44 4 x
  > EOF
  Make changes as needed, you may commit or record as needed now.
  When you are finished, run hg histedit --continue to resume.
  [1]
  $ echo edit >> alpha
  $ hg histedit -q --continue
  $ hg log -G -T '{rev}:{node|short} {desc}'
  @  6:8fda0c726bf2 x
  |
  o  5:63379946892c three
  |
  | o  4:f3cfcca30c44 x
  | |
  | | o  3:2a30f3cfee78 four
  | |/   ***
  | |    five
  | o  2:eb57da33312f three
  |/
  o  1:579e40513370 two
  |
  o  0:6058cbb6cfd7 one
  

Test that abort fails gracefully on exception
----------------------------------------------
  $ hg histedit . -q --commands - << EOF
  > edit 8fda0c726bf2 6 x
  > EOF
  Make changes as needed, you may commit or record as needed now.
  When you are finished, run hg histedit --continue to resume.
  [1]
Corrupt histedit state file
  $ sed 's/8fda0c726bf2/123456789012/' .hg/histedit-state > ../corrupt-histedit
  $ mv ../corrupt-histedit .hg/histedit-state
  $ hg histedit --abort
  warning: encountered an exception during histedit --abort; the repository may not have been completely cleaned up
  abort: No such file or directory: * (glob)
  [255]
Histedit state has been exited
  $ hg summary -q
  parent: 5:63379946892c 
  commit: 1 added, 1 unknown (new branch head)
  update: 4 new changesets (update)