view tests/test-histedit-commute.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.

  $ . "$TESTDIR/histedit-helpers.sh"

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > histedit=
  > EOF

  $ initrepo ()
  > {
  >     hg init r
  >     cd r
  >     for x in a b c d e f ; do
  >         echo $x > $x
  >         hg add $x
  >         hg ci -m $x
  >     done
  > }

  $ initrepo

log before edit
  $ hg log --graph
  @  changeset:   5:652413bf663e
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   4:e860deea161a
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   3:055a42cdd887
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   2:177f92b77385
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

show the edit commands offered
  $ HGEDITOR=cat hg histedit 177f92b77385
  pick 177f92b77385 2 c
  pick 055a42cdd887 3 d
  pick e860deea161a 4 e
  pick 652413bf663e 5 f
  
  # Edit history between 177f92b77385 and 652413bf663e
  #
  # 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

edit the history
(use a hacky editor to check histedit-last-edit.txt backup)

  $ EDITED="$TESTTMP/editedhistory"
  $ cat > $EDITED <<EOF
  > pick 177f92b77385 c
  > pick e860deea161a e
  > pick 652413bf663e f
  > pick 055a42cdd887 d
  > EOF
  $ HGEDITOR="cat \"$EDITED\" > " hg histedit 177f92b77385 2>&1 | fixbundle
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

rules should end up in .hg/histedit-last-edit.txt:
  $ cat .hg/histedit-last-edit.txt
  pick 177f92b77385 c
  pick e860deea161a e
  pick 652413bf663e f
  pick 055a42cdd887 d

log after edit
  $ hg log --graph
  @  changeset:   5:07114f51870f
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   4:8ade9693061e
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   3:d8249471110a
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   2:177f92b77385
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

put things back

  $ hg histedit 177f92b77385 --commands - 2>&1 << EOF | fixbundle
  > pick 177f92b77385 c
  > pick 07114f51870f d
  > pick d8249471110a e
  > pick 8ade9693061e f
  > EOF
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg log --graph
  @  changeset:   5:7eca9b5b1148
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   4:915da888f2de
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   3:10517e47bbbb
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   2:177f92b77385
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

slightly different this time

  $ hg histedit 177f92b77385 --commands - << EOF 2>&1 | fixbundle
  > pick 10517e47bbbb d
  > pick 7eca9b5b1148 f
  > pick 915da888f2de e
  > pick 177f92b77385 c
  > EOF
  0 files updated, 0 files merged, 4 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log --graph
  @  changeset:   5:38b92f448761
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   4:de71b079d9ce
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   2:799205341b6b
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

keep prevents stripping dead revs
  $ hg histedit 799205341b6b --keep --commands - 2>&1 << EOF | fixbundle
  > pick 799205341b6b d
  > pick be9ae3a309c6 f
  > pick 38b92f448761 c
  > pick de71b079d9ce e
  > EOF
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log --graph
  @  changeset:   7:803ef1c6fcfd
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   6:ece0b8d93dda
  |  parent:      3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  | o  changeset:   5:38b92f448761
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     c
  | |
  | o  changeset:   4:de71b079d9ce
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     e
  |
  o  changeset:   3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   2:799205341b6b
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

try with --rev
  $ hg histedit --commands - --rev -2 2>&1 <<EOF | fixbundle
  > pick de71b079d9ce e
  > pick 38b92f448761 c
  > EOF
  abort: may not use changesets other than the ones listed
  $ hg log --graph
  @  changeset:   7:803ef1c6fcfd
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   6:ece0b8d93dda
  |  parent:      3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  | o  changeset:   5:38b92f448761
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     c
  | |
  | o  changeset:   4:de71b079d9ce
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     e
  |
  o  changeset:   3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   2:799205341b6b
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  
Verify that revsetalias entries work with histedit:
  $ cat >> $HGRCPATH <<EOF
  > [revsetalias]
  > grandparent(ARG) = p1(p1(ARG))
  > EOF
  $ echo extra commit >> c
  $ hg ci -m 'extra commit to c'
  $ HGEDITOR=cat hg histedit 'grandparent(.)'
  pick ece0b8d93dda 6 c
  pick 803ef1c6fcfd 7 e
  pick 9c863c565126 8 extra commit to c
  
  # Edit history between ece0b8d93dda and 9c863c565126
  #
  # 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

should also work if a commit message is missing
  $ BUNDLE="$TESTDIR/missing-comment.hg"
  $ hg init missing
  $ cd missing
  $ hg unbundle $BUNDLE
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files
  (run 'hg update' to get a working copy)
  $ hg co tip
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log --graph
  @  changeset:   2:bd22688093b3
  |  tag:         tip
  |  user:        Robert Altman <[e-mail]>
  |  date:        Mon Nov 28 16:40:04 2011 +0000
  |  summary:     Update file.
  |
  o  changeset:   1:3b3e956f9171
  |  user:        Robert Altman <[e-mail]>
  |  date:        Mon Nov 28 16:37:57 2011 +0000
  |
  o  changeset:   0:141947992243
     user:        Robert Altman <[e-mail]>
     date:        Mon Nov 28 16:35:28 2011 +0000
     summary:     Checked in text file
  
  $ hg histedit 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ..

  $ cd ..


Test to make sure folding renames doesn't cause bogus conflicts (issue4251):
  $ hg init issue4251
  $ cd issue4251

  $ mkdir initial-dir
  $ echo foo > initial-dir/initial-file
  $ hg add initial-dir/initial-file
  $ hg commit -m "initial commit"

Move the file to a new directory, and in the same commit, change its content:
  $ mkdir another-dir
  $ hg mv initial-dir/initial-file another-dir/
  $ echo changed > another-dir/initial-file
  $ hg commit -m "moved and changed"

Rename the file:
  $ hg mv another-dir/initial-file another-dir/renamed-file
  $ hg commit -m "renamed"

Now, let's try to fold the second commit into the first:
  $ cat > editor.sh <<EOF
  > #!/bin/sh
  > cat > \$1 <<ENDOF
  > pick b0f4233702ca 0 initial commit
  > fold 5e8704a8f2d2 1 moved and changed
  > pick 40e7299e8fa7 2 renamed
  > ENDOF
  > EOF

  $ HGEDITOR="sh ./editor.sh" hg histedit 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  adding another-dir/initial-file (glob)
  removing initial-dir/initial-file (glob)
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  0 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/issue4251/.hg/strip-backup/*-backup.hg (glob)

  $ hg --config diff.git=yes export 0
  # HG changeset patch
  # User test
  # Date 0 0
  #      Thu Jan 01 00:00:00 1970 +0000
  # Node ID fffadc26f8f85623ce60b028a3f1ccc3730f8530
  # Parent  0000000000000000000000000000000000000000
  pick b0f4233702ca 0 initial commit
  fold 5e8704a8f2d2 1 moved and changed
  pick 40e7299e8fa7 2 renamed
  
  diff --git a/another-dir/initial-file b/another-dir/initial-file
  new file mode 100644
  --- /dev/null
  +++ b/another-dir/initial-file
  @@ -0,0 +1,1 @@
  +changed

  $ hg --config diff.git=yes export 1
  # HG changeset patch
  # User test
  # Date 0 0
  #      Thu Jan 01 00:00:00 1970 +0000
  # Node ID 9b730d82b00af8a2766facebfa47cc124405a118
  # Parent  fffadc26f8f85623ce60b028a3f1ccc3730f8530
  renamed
  
  diff --git a/another-dir/initial-file b/another-dir/renamed-file
  rename from another-dir/initial-file
  rename to another-dir/renamed-file

  $ cd ..