view tests/test-branches.t @ 40021:c537144fdbef

wireprotov2: support response caching

One of the things I've learned from managing VCS servers over the
years is that they are hard to scale. It is well known that some
companies have very beefy (read: very expensive) servers to power
their VCS needs. It is also known that specialized servers for
various VCS exist in order to facilitate scaling servers. (Mercurial
is in this boat.)

One of the aspects that make a VCS server hard to scale is the
high CPU load incurred by constant client clone/pull operations.

To alleviate the scaling pain associated with data retrieval
operations, I want to integrate caching into the Mercurial wire
protocol server as robustly as possible such that servers can
aggressively cache responses and defer as much server load as
possible.

This commit represents the initial implementation of a general
caching layer in wire protocol version 2.

We define a new interface and behavior for a wire protocol cacher
in repository.py. (This is probably where a reviewer should look
first to understand what is going on.)

The bulk of the added code is in wireprotov2server.py, where we
define how a command can opt in to being cached and integrate
caching into command dispatching.

From a very high-level:

* A command can declare itself as cacheable by providing a callable
  that can be used to derive a cache key.
* At dispatch time, if a command is cacheable, we attempt to
  construct a cacher and use it for serving the request and/or
  caching the request.
* The dispatch layer handles the bulk of the business logic for
  caching, making cachers mostly "dumb content stores."
* The mechanism for invalidating cached entries (one of the harder
  parts about caching in general) is by varying the cache key when
  state changes. As such, cachers don't need to be concerned with
  cache invalidation.

Initially, we've hooked up support for caching "manifestdata" and
"filedata" commands. These are the simplest to cache, as they should
be immutable over time. Caching of commands related to changeset
data is a bit harder (because cache validation is impacted by
changes to bookmarks, phases, etc). This will be implemented later.
(Strictly speaking, censoring a file should invalidate caches. I've
added an inline TODO to track this edge case.)

To prove it works, this commit implements a test-only extension
providing in-memory caching backed by an lrucachedict. A new test
showing this extension behaving properly is added. FWIW, the
cacher is ~50 lines of code, demonstrating the relative ease with
which a cache can be added to a server.

While the test cacher is not suitable for production workloads, just
for kicks I performed a clone of just the changeset and manifest data
for the mozilla-unified repository. With a fully warmed cache (of just
the manifest data since changeset data is not cached), server-side
CPU usage dropped from ~73s to ~28s. That's pretty significant and
demonstrates the potential that response caching has on server
scalability!

Differential Revision: https://phab.mercurial-scm.org/D4773

  $ hg init a
  $ cd a

Verify checking branch of nullrev before the cache is created doesnt crash
  $ hg log -r 'branch(.)' -T '{branch}\n'

Basic test
  $ echo 'root' >root
  $ hg add root
  $ hg commit -d '0 0' -m "Adding root node"

  $ echo 'a' >a
  $ hg add a
  $ hg branch a
  marked working directory as branch a
  (branches are permanent and global, did you want a bookmark?)
  $ hg commit -d '1 0' -m "Adding a branch"

  $ hg branch q
  marked working directory as branch q
  $ echo 'aa' >a
  $ hg branch -C
  reset working directory to branch a
  $ hg commit -d '2 0' -m "Adding to a branch"

  $ hg update -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo 'b' >b
  $ hg add b
  $ hg branch b
  marked working directory as branch b
  $ hg commit -d '2 0' -m "Adding b branch"

  $ echo 'bh1' >bh1
  $ hg add bh1
  $ hg commit -d '3 0' -m "Adding b branch head 1"

  $ hg update -C 2
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ echo 'bh2' >bh2
  $ hg add bh2
  $ hg commit -d '4 0' -m "Adding b branch head 2"

  $ echo 'c' >c
  $ hg add c
  $ hg branch c
  marked working directory as branch c
  $ hg commit -d '5 0' -m "Adding c branch"

reserved names

  $ hg branch tip
  abort: the name 'tip' is reserved
  [255]
  $ hg branch null
  abort: the name 'null' is reserved
  [255]
  $ hg branch .
  abort: the name '.' is reserved
  [255]

invalid characters

  $ hg branch 'foo:bar'
  abort: ':' cannot be used in a name
  [255]

  $ hg branch 'foo
  > bar'
  abort: '\n' cannot be used in a name
  [255]

trailing or leading spaces should be stripped before testing duplicates

  $ hg branch 'b '
  abort: a branch of the same name already exists
  (use 'hg update' to switch to it)
  [255]

  $ hg branch ' b'
  abort: a branch of the same name already exists
  (use 'hg update' to switch to it)
  [255]

verify update will accept invalid legacy branch names

  $ hg init test-invalid-branch-name
  $ cd test-invalid-branch-name
  $ hg unbundle -u "$TESTDIR"/bundles/test-invalid-branch-name.hg
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files
  new changesets f0e4c7f04036:33c2ceb9310b (3 drafts)
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg update '"colon:test"'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ..

  $ echo 'd' >d
  $ hg add d
  $ hg branch 'a branch name much longer than the default justification used by branches'
  marked working directory as branch a branch name much longer than the default justification used by branches
  $ hg commit -d '6 0' -m "Adding d branch"

  $ hg branches
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  b                              4:aee39cd168d0
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)

-------

  $ hg branches -a
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  b                              4:aee39cd168d0

--- Branch a

  $ hg log -b a
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  changeset:   2:881fe2b92ad0
  branch:      a
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     Adding to a branch
  
  changeset:   1:dd6b440dd85a
  branch:      a
  user:        test
  date:        Thu Jan 01 00:00:01 1970 +0000
  summary:     Adding a branch
  

---- Branch b

  $ hg log -b b
  changeset:   4:aee39cd168d0
  branch:      b
  user:        test
  date:        Thu Jan 01 00:00:03 1970 +0000
  summary:     Adding b branch head 1
  
  changeset:   3:ac22033332d1
  branch:      b
  parent:      0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:02 1970 +0000
  summary:     Adding b branch
  

---- going to test branch closing

  $ hg branches
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  b                              4:aee39cd168d0
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)
  $ hg up -C b
  2 files updated, 0 files merged, 4 files removed, 0 files unresolved
  $ echo 'xxx1' >> b
  $ hg commit -d '7 0' -m 'adding cset to branch b'
  $ hg up -C aee39cd168d0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo 'xxx2' >> b
  $ hg commit -d '8 0' -m 'adding head to branch b'
  created new head
  $ echo 'xxx3' >> b
  $ hg commit -d '9 0' -m 'adding another cset to branch b'
  $ hg branches
  b                             10:bfbe841b666e
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)
  $ hg heads --closed
  changeset:   10:bfbe841b666e
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     adding another cset to branch b
  
  changeset:   8:eebb944467c9
  branch:      b
  parent:      4:aee39cd168d0
  user:        test
  date:        Thu Jan 01 00:00:07 1970 +0000
  summary:     adding cset to branch b
  
  changeset:   7:10ff5895aa57
  branch:      a branch name much longer than the default justification used by branches
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     Adding d branch
  
  changeset:   6:589736a22561
  branch:      c
  user:        test
  date:        Thu Jan 01 00:00:05 1970 +0000
  summary:     Adding c branch
  
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  changeset:   0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Adding root node
  
  $ hg heads
  changeset:   10:bfbe841b666e
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     adding another cset to branch b
  
  changeset:   8:eebb944467c9
  branch:      b
  parent:      4:aee39cd168d0
  user:        test
  date:        Thu Jan 01 00:00:07 1970 +0000
  summary:     adding cset to branch b
  
  changeset:   7:10ff5895aa57
  branch:      a branch name much longer than the default justification used by branches
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     Adding d branch
  
  changeset:   6:589736a22561
  branch:      c
  user:        test
  date:        Thu Jan 01 00:00:05 1970 +0000
  summary:     Adding c branch
  
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  changeset:   0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Adding root node
  
  $ hg commit -d '9 0' --close-branch -m 'prune bad branch'
  $ hg branches -a
  b                              8:eebb944467c9
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  $ hg up -C b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg commit -d '9 0' --close-branch -m 'close this part branch too'
  $ hg commit -d '9 0' --close-branch -m 're-closing this branch'
  abort: can only close branch heads
  [255]

  $ hg log -r tip --debug
  changeset:   12:e3d49c0575d8fc2cb1cd6859c747c14f5f6d499f
  branch:      b
  tag:         tip
  phase:       draft
  parent:      8:eebb944467c9fb9651ed232aeaf31b3c0a7fc6c1
  parent:      -1:0000000000000000000000000000000000000000
  manifest:    8:6f9ed32d2b310e391a4f107d5f0f071df785bfee
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  extra:       branch=b
  extra:       close=1
  description:
  close this part branch too
  
  
--- b branch should be inactive

  $ hg branches
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)
  $ hg branches -c
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  b                             12:e3d49c0575d8 (closed)
  c                              6:589736a22561 (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)
  $ hg branches -a
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  $ hg branches -q
  a branch name much longer than the default justification used by branches
  c
  a
  default
  $ hg heads b
  no open branch heads found on branches b
  [1]
  $ hg heads --closed b
  changeset:   12:e3d49c0575d8
  branch:      b
  tag:         tip
  parent:      8:eebb944467c9
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     close this part branch too
  
  changeset:   11:d3f163457ebf
  branch:      b
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     prune bad branch
  
  $ echo 'xxx4' >> b
  $ hg commit -d '9 0' -m 'reopen branch with a change'
  reopening closed branch head 12

--- branch b is back in action

  $ hg branches -a
  b                             13:e23b5505d1ad
  a branch name much longer than the default justification used by branches 7:10ff5895aa57

---- test heads listings

  $ hg heads
  changeset:   13:e23b5505d1ad
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     reopen branch with a change
  
  changeset:   7:10ff5895aa57
  branch:      a branch name much longer than the default justification used by branches
  user:        test
  date:        Thu Jan 01 00:00:06 1970 +0000
  summary:     Adding d branch
  
  changeset:   6:589736a22561
  branch:      c
  user:        test
  date:        Thu Jan 01 00:00:05 1970 +0000
  summary:     Adding c branch
  
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  changeset:   0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Adding root node
  

branch default

  $ hg heads default
  changeset:   0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     Adding root node
  

branch a

  $ hg heads a
  changeset:   5:d8cbc61dbaa6
  branch:      a
  parent:      2:881fe2b92ad0
  user:        test
  date:        Thu Jan 01 00:00:04 1970 +0000
  summary:     Adding b branch head 2
  
  $ hg heads --active a
  no open branch heads found on branches a
  [1]

branch b

  $ hg heads b
  changeset:   13:e23b5505d1ad
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     reopen branch with a change
  
  $ hg heads --closed b
  changeset:   13:e23b5505d1ad
  branch:      b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     reopen branch with a change
  
  changeset:   11:d3f163457ebf
  branch:      b
  user:        test
  date:        Thu Jan 01 00:00:09 1970 +0000
  summary:     prune bad branch
  

reclose branch

  $ hg up -C c
  3 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg commit -d '9 0' --close-branch -m 'reclosing this branch'
  $ hg branches
  b                             13:e23b5505d1ad
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)
  $ hg branches --closed
  b                             13:e23b5505d1ad
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  c                             14:f894c25619d3 (closed)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)

multihead branch

  $ hg up -C default
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ hg branch m
  marked working directory as branch m
  $ touch m
  $ hg add m
  $ hg commit -d '10 0' -m 'multihead base'
  $ echo "m1" >m
  $ hg commit -d '10 0' -m 'head 1'
  $ hg up -C '.^'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "m2" >m
  $ hg commit -d '10 0' -m 'head 2'
  created new head
  $ hg log -b m
  changeset:   17:df343b0df04f
  branch:      m
  tag:         tip
  parent:      15:f3447637f53e
  user:        test
  date:        Thu Jan 01 00:00:10 1970 +0000
  summary:     head 2
  
  changeset:   16:a58ca5d3bdf3
  branch:      m
  user:        test
  date:        Thu Jan 01 00:00:10 1970 +0000
  summary:     head 1
  
  changeset:   15:f3447637f53e
  branch:      m
  parent:      0:19709c5a4e75
  user:        test
  date:        Thu Jan 01 00:00:10 1970 +0000
  summary:     multihead base
  
  $ hg heads --topo m
  changeset:   17:df343b0df04f
  branch:      m
  tag:         tip
  parent:      15:f3447637f53e
  user:        test
  date:        Thu Jan 01 00:00:10 1970 +0000
  summary:     head 2
  
  changeset:   16:a58ca5d3bdf3
  branch:      m
  user:        test
  date:        Thu Jan 01 00:00:10 1970 +0000
  summary:     head 1
  
  $ hg branches
  m                             17:df343b0df04f
  b                             13:e23b5505d1ad
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)

partially merge multihead branch

  $ hg up -C default
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg branch md
  marked working directory as branch md
  $ hg merge m
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -d '11 0' -m 'merge head 2'
  $ hg heads --topo m
  changeset:   16:a58ca5d3bdf3
  branch:      m
  user:        test
  date:        Thu Jan 01 00:00:10 1970 +0000
  summary:     head 1
  
  $ hg branches
  md                            18:c914c99f1fbb
  m                             17:df343b0df04f
  b                             13:e23b5505d1ad
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)

partially close multihead branch

  $ hg up -C a58ca5d3bdf3
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg commit -d '12 0' -m 'close head 1' --close-branch
  $ hg heads --topo m
  changeset:   19:cd21a80baa3d
  branch:      m
  tag:         tip
  parent:      16:a58ca5d3bdf3
  user:        test
  date:        Thu Jan 01 00:00:12 1970 +0000
  summary:     close head 1
  
  $ hg branches
  md                            18:c914c99f1fbb
  b                             13:e23b5505d1ad
  a branch name much longer than the default justification used by branches 7:10ff5895aa57
  m                             17:df343b0df04f (inactive)
  a                              5:d8cbc61dbaa6 (inactive)
  default                        0:19709c5a4e75 (inactive)

default branch colors:

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > color =
  > [color]
  > mode = ansi
  > EOF

  $ hg up -C b
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg branches --color=always
  \x1b[0;0mmd\x1b[0m\x1b[0;33m                            18:c914c99f1fbb\x1b[0m (esc)
  \x1b[0;32mb\x1b[0m\x1b[0;33m                             13:e23b5505d1ad\x1b[0m (esc)
  \x1b[0;0ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;33m 7:10ff5895aa57\x1b[0m (esc)
  \x1b[0;0mm\x1b[0m\x1b[0;33m                             17:df343b0df04f\x1b[0m (inactive) (esc)
  \x1b[0;0ma\x1b[0m\x1b[0;33m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
  \x1b[0;0mdefault\x1b[0m\x1b[0;33m                        0:19709c5a4e75\x1b[0m (inactive) (esc)

default closed branch color:

  $ hg branches --color=always --closed
  \x1b[0;0mmd\x1b[0m\x1b[0;33m                            18:c914c99f1fbb\x1b[0m (esc)
  \x1b[0;32mb\x1b[0m\x1b[0;33m                             13:e23b5505d1ad\x1b[0m (esc)
  \x1b[0;0ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;33m 7:10ff5895aa57\x1b[0m (esc)
  \x1b[0;0mm\x1b[0m\x1b[0;33m                             17:df343b0df04f\x1b[0m (inactive) (esc)
  \x1b[0;30;1mc\x1b[0m\x1b[0;33m                             14:f894c25619d3\x1b[0m (closed) (esc)
  \x1b[0;0ma\x1b[0m\x1b[0;33m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
  \x1b[0;0mdefault\x1b[0m\x1b[0;33m                        0:19709c5a4e75\x1b[0m (inactive) (esc)

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > color =
  > [color]
  > branches.active = green
  > branches.closed = blue
  > branches.current = red
  > branches.inactive = magenta
  > log.changeset = cyan
  > EOF

custom branch colors:

  $ hg branches --color=always
  \x1b[0;32mmd\x1b[0m\x1b[0;36m                            18:c914c99f1fbb\x1b[0m (esc)
  \x1b[0;31mb\x1b[0m\x1b[0;36m                             13:e23b5505d1ad\x1b[0m (esc)
  \x1b[0;32ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;36m 7:10ff5895aa57\x1b[0m (esc)
  \x1b[0;35mm\x1b[0m\x1b[0;36m                             17:df343b0df04f\x1b[0m (inactive) (esc)
  \x1b[0;35ma\x1b[0m\x1b[0;36m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
  \x1b[0;35mdefault\x1b[0m\x1b[0;36m                        0:19709c5a4e75\x1b[0m (inactive) (esc)

custom closed branch color:

  $ hg branches --color=always --closed
  \x1b[0;32mmd\x1b[0m\x1b[0;36m                            18:c914c99f1fbb\x1b[0m (esc)
  \x1b[0;31mb\x1b[0m\x1b[0;36m                             13:e23b5505d1ad\x1b[0m (esc)
  \x1b[0;32ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;36m 7:10ff5895aa57\x1b[0m (esc)
  \x1b[0;35mm\x1b[0m\x1b[0;36m                             17:df343b0df04f\x1b[0m (inactive) (esc)
  \x1b[0;34mc\x1b[0m\x1b[0;36m                             14:f894c25619d3\x1b[0m (closed) (esc)
  \x1b[0;35ma\x1b[0m\x1b[0;36m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
  \x1b[0;35mdefault\x1b[0m\x1b[0;36m                        0:19709c5a4e75\x1b[0m (inactive) (esc)

template output:

  $ hg branches -Tjson --closed
  [
   {
    "active": true,
    "branch": "md",
    "closed": false,
    "current": false,
    "node": "c914c99f1fbb2b1d785a0a939ed3f67275df18e9",
    "rev": 18
   },
   {
    "active": true,
    "branch": "b",
    "closed": false,
    "current": true,
    "node": "e23b5505d1ad24aab6f84fd8c7cb8cd8e5e93be0",
    "rev": 13
   },
   {
    "active": true,
    "branch": "a branch name much longer than the default justification used by branches",
    "closed": false,
    "current": false,
    "node": "10ff5895aa5793bd378da574af8cec8ea408d831",
    "rev": 7
   },
   {
    "active": false,
    "branch": "m",
    "closed": false,
    "current": false,
    "node": "df343b0df04feb2a946cd4b6e9520e552fef14ee",
    "rev": 17
   },
   {
    "active": false,
    "branch": "c",
    "closed": true,
    "current": false,
    "node": "f894c25619d3f1484639d81be950e0a07bc6f1f6",
    "rev": 14
   },
   {
    "active": false,
    "branch": "a",
    "closed": false,
    "current": false,
    "node": "d8cbc61dbaa6dc817175d1e301eecb863f280832",
    "rev": 5
   },
   {
    "active": false,
    "branch": "default",
    "closed": false,
    "current": false,
    "node": "19709c5a4e75bf938f8e349aff97438539bb729e",
    "rev": 0
   }
  ]

  $ hg branches --closed -T '{if(closed, "{branch}\n")}'
  c

  $ hg branches -T '{word(0, branch)}: {desc|firstline}\n'
  md: merge head 2
  b: reopen branch with a change
  a: Adding d branch
  m: head 2
  a: Adding b branch head 2
  default: Adding root node

  $ cat <<'EOF' > "$TESTTMP/map-myjson"
  > docheader = '\{\n'
  > docfooter = '\n}\n'
  > separator = ',\n'
  > branches = ' {dict(branch, node|short)|json}'
  > EOF
  $ hg branches -T "$TESTTMP/map-myjson"
  {
   {"branch": "md", "node": "c914c99f1fbb"},
   {"branch": "b", "node": "e23b5505d1ad"},
   {"branch": "a branch *", "node": "10ff5895aa57"}, (glob)
   {"branch": "m", "node": "df343b0df04f"},
   {"branch": "a", "node": "d8cbc61dbaa6"},
   {"branch": "default", "node": "19709c5a4e75"}
  }

  $ cat <<'EOF' >> .hg/hgrc
  > [templates]
  > myjson = ' {dict(branch, node|short)|json}'
  > myjson:docheader = '\{\n'
  > myjson:docfooter = '\n}\n'
  > myjson:separator = ',\n'
  > EOF
  $ hg branches -T myjson
  {
   {"branch": "md", "node": "c914c99f1fbb"},
   {"branch": "b", "node": "e23b5505d1ad"},
   {"branch": "a branch *", "node": "10ff5895aa57"}, (glob)
   {"branch": "m", "node": "df343b0df04f"},
   {"branch": "a", "node": "d8cbc61dbaa6"},
   {"branch": "default", "node": "19709c5a4e75"}
  }

  $ cat <<'EOF' >> .hg/hgrc
  > [templates]
  > :docheader = 'should not be selected as a docheader for literal templates\n'
  > EOF
  $ hg branches -T '{branch}\n'
  md
  b
  a branch name much longer than the default justification used by branches
  m
  a
  default

Tests of revision branch name caching

We rev branch cache is updated automatically. In these tests we use a trick to
trigger rebuilds. We remove the branch head cache and run 'hg head' to cause a
rebuild that also will populate the rev branch cache.

revision branch cache is created when building the branch head cache
  $ rm -rf .hg/cache; hg head a -T '{rev}\n'
  5
  $ f --hexdump --size .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=92
  0000: 64 65 66 61 75 6c 74 00 61 00 62 00 63 00 61 20 |default.a.b.c.a |
  0010: 62 72 61 6e 63 68 20 6e 61 6d 65 20 6d 75 63 68 |branch name much|
  0020: 20 6c 6f 6e 67 65 72 20 74 68 61 6e 20 74 68 65 | longer than the|
  0030: 20 64 65 66 61 75 6c 74 20 6a 75 73 74 69 66 69 | default justifi|
  0040: 63 61 74 69 6f 6e 20 75 73 65 64 20 62 79 20 62 |cation used by b|
  0050: 72 61 6e 63 68 65 73 00 6d 00 6d 64             |ranches.m.md|
  .hg/cache/rbc-revs-v1: size=160
  0000: 19 70 9c 5a 00 00 00 00 dd 6b 44 0d 00 00 00 01 |.p.Z.....kD.....|
  0010: 88 1f e2 b9 00 00 00 01 ac 22 03 33 00 00 00 02 |.........".3....|
  0020: ae e3 9c d1 00 00 00 02 d8 cb c6 1d 00 00 00 01 |................|
  0030: 58 97 36 a2 00 00 00 03 10 ff 58 95 00 00 00 04 |X.6.......X.....|
  0040: ee bb 94 44 00 00 00 02 5f 40 61 bb 00 00 00 02 |...D...._@a.....|
  0050: bf be 84 1b 00 00 00 02 d3 f1 63 45 80 00 00 02 |..........cE....|
  0060: e3 d4 9c 05 80 00 00 02 e2 3b 55 05 00 00 00 02 |.........;U.....|
  0070: f8 94 c2 56 80 00 00 03 f3 44 76 37 00 00 00 05 |...V.....Dv7....|
  0080: a5 8c a5 d3 00 00 00 05 df 34 3b 0d 00 00 00 05 |.........4;.....|
  0090: c9 14 c9 9f 00 00 00 06 cd 21 a8 0b 80 00 00 05 |.........!......|

no errors when revbranchcache is not writable

  $ echo >> .hg/cache/rbc-revs-v1
  $ mv .hg/cache/rbc-revs-v1 .hg/cache/rbc-revs-v1_
  $ mkdir .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n'
  5
  $ rmdir .hg/cache/rbc-revs-v1
  $ mv .hg/cache/rbc-revs-v1_ .hg/cache/rbc-revs-v1

no errors when wlock cannot be acquired

#if unix-permissions
  $ mv .hg/cache/rbc-revs-v1 .hg/cache/rbc-revs-v1_
  $ rm -f .hg/cache/branch*
  $ chmod 555 .hg
  $ hg head a -T '{rev}\n'
  5
  $ chmod 755 .hg
  $ mv .hg/cache/rbc-revs-v1_ .hg/cache/rbc-revs-v1
#endif

recovery from invalid cache revs file with trailing data
  $ echo >> .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5
  truncating cache/rbc-revs-v1 to 160
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=160
recovery from invalid cache file with partial last record
  $ mv .hg/cache/rbc-revs-v1 .
  $ f -qDB 119 rbc-revs-v1 > .hg/cache/rbc-revs-v1
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=119
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5
  truncating cache/rbc-revs-v1 to 112
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=160
recovery from invalid cache file with missing record - no truncation
  $ mv .hg/cache/rbc-revs-v1 .
  $ f -qDB 112 rbc-revs-v1 > .hg/cache/rbc-revs-v1
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=160
recovery from invalid cache file with some bad records
  $ mv .hg/cache/rbc-revs-v1 .
  $ f -qDB 8 rbc-revs-v1 > .hg/cache/rbc-revs-v1
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=8
  $ f -qDB 112 rbc-revs-v1 >> .hg/cache/rbc-revs-v1
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=120
  $ hg log -r 'branch(.)' -T '{rev} ' --debug
  history modification detected - truncating revision branch cache to revision 13
  history modification detected - truncating revision branch cache to revision 1
  3 4 8 9 10 11 12 13 truncating cache/rbc-revs-v1 to 8
  $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
  5
  truncating cache/rbc-revs-v1 to 104
  $ f --size --hexdump --bytes=16 .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=160
  0000: 19 70 9c 5a 00 00 00 00 dd 6b 44 0d 00 00 00 01 |.p.Z.....kD.....|
cache is updated when committing
  $ hg branch i-will-regret-this
  marked working directory as branch i-will-regret-this
  $ hg ci -m regrets
  $ f --size .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=111
  .hg/cache/rbc-revs-v1: size=168
update after rollback - the cache will be correct but rbc-names will will still
contain the branch name even though it no longer is used
  $ hg up -qr '.^'
  $ hg rollback -qf
  $ f --size --hexdump .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=111
  0000: 64 65 66 61 75 6c 74 00 61 00 62 00 63 00 61 20 |default.a.b.c.a |
  0010: 62 72 61 6e 63 68 20 6e 61 6d 65 20 6d 75 63 68 |branch name much|
  0020: 20 6c 6f 6e 67 65 72 20 74 68 61 6e 20 74 68 65 | longer than the|
  0030: 20 64 65 66 61 75 6c 74 20 6a 75 73 74 69 66 69 | default justifi|
  0040: 63 61 74 69 6f 6e 20 75 73 65 64 20 62 79 20 62 |cation used by b|
  0050: 72 61 6e 63 68 65 73 00 6d 00 6d 64 00 69 2d 77 |ranches.m.md.i-w|
  0060: 69 6c 6c 2d 72 65 67 72 65 74 2d 74 68 69 73    |ill-regret-this|
  .hg/cache/rbc-revs-v1: size=160
  0000: 19 70 9c 5a 00 00 00 00 dd 6b 44 0d 00 00 00 01 |.p.Z.....kD.....|
  0010: 88 1f e2 b9 00 00 00 01 ac 22 03 33 00 00 00 02 |.........".3....|
  0020: ae e3 9c d1 00 00 00 02 d8 cb c6 1d 00 00 00 01 |................|
  0030: 58 97 36 a2 00 00 00 03 10 ff 58 95 00 00 00 04 |X.6.......X.....|
  0040: ee bb 94 44 00 00 00 02 5f 40 61 bb 00 00 00 02 |...D...._@a.....|
  0050: bf be 84 1b 00 00 00 02 d3 f1 63 45 80 00 00 02 |..........cE....|
  0060: e3 d4 9c 05 80 00 00 02 e2 3b 55 05 00 00 00 02 |.........;U.....|
  0070: f8 94 c2 56 80 00 00 03 f3 44 76 37 00 00 00 05 |...V.....Dv7....|
  0080: a5 8c a5 d3 00 00 00 05 df 34 3b 0d 00 00 00 05 |.........4;.....|
  0090: c9 14 c9 9f 00 00 00 06 cd 21 a8 0b 80 00 00 05 |.........!......|
cache is updated/truncated when stripping - it is thus very hard to get in a
situation where the cache is out of sync and the hash check detects it
  $ hg --config extensions.strip= strip -r tip --nob
  $ f --size .hg/cache/rbc-revs*
  .hg/cache/rbc-revs-v1: size=152

cache is rebuilt when corruption is detected
  $ echo > .hg/cache/rbc-names-v1
  $ hg log -r '5:&branch(.)' -T '{rev} ' --debug
  referenced branch names not found - rebuilding revision branch cache from scratch
  8 9 10 11 12 13 truncating cache/rbc-revs-v1 to 40
  $ f --size --hexdump .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=84
  0000: 62 00 61 00 63 00 61 20 62 72 61 6e 63 68 20 6e |b.a.c.a branch n|
  0010: 61 6d 65 20 6d 75 63 68 20 6c 6f 6e 67 65 72 20 |ame much longer |
  0020: 74 68 61 6e 20 74 68 65 20 64 65 66 61 75 6c 74 |than the default|
  0030: 20 6a 75 73 74 69 66 69 63 61 74 69 6f 6e 20 75 | justification u|
  0040: 73 65 64 20 62 79 20 62 72 61 6e 63 68 65 73 00 |sed by branches.|
  0050: 6d 00 6d 64                                     |m.md|
  .hg/cache/rbc-revs-v1: size=152
  0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0020: 00 00 00 00 00 00 00 00 d8 cb c6 1d 00 00 00 01 |................|
  0030: 58 97 36 a2 00 00 00 02 10 ff 58 95 00 00 00 03 |X.6.......X.....|
  0040: ee bb 94 44 00 00 00 00 5f 40 61 bb 00 00 00 00 |...D...._@a.....|
  0050: bf be 84 1b 00 00 00 00 d3 f1 63 45 80 00 00 00 |..........cE....|
  0060: e3 d4 9c 05 80 00 00 00 e2 3b 55 05 00 00 00 00 |.........;U.....|
  0070: f8 94 c2 56 80 00 00 02 f3 44 76 37 00 00 00 04 |...V.....Dv7....|
  0080: a5 8c a5 d3 00 00 00 04 df 34 3b 0d 00 00 00 04 |.........4;.....|
  0090: c9 14 c9 9f 00 00 00 05                         |........|

Test that cache files are created and grows correctly:

  $ rm .hg/cache/rbc*
  $ hg log -r "5 & branch(5)" -T "{rev}\n"
  5
  $ f --size --hexdump .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=1
  0000: 61                                              |a|
  .hg/cache/rbc-revs-v1: size=152
  0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0020: 00 00 00 00 00 00 00 00 d8 cb c6 1d 00 00 00 00 |................|
  0030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  0090: 00 00 00 00 00 00 00 00                         |........|

  $ cd ..

Test for multiple incorrect branch cache entries:

  $ hg init b
  $ cd b
  $ touch f
  $ hg ci -Aqmf
  $ echo >> f
  $ hg ci -Amf
  $ hg branch -q branch
  $ hg ci -Amf

  $ f --size --hexdump .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=14
  0000: 64 65 66 61 75 6c 74 00 62 72 61 6e 63 68       |default.branch|
  .hg/cache/rbc-revs-v1: size=24
  0000: 66 e5 f5 aa 00 00 00 00 fa 4c 04 e5 00 00 00 00 |f........L......|
  0010: 56 46 78 69 00 00 00 01                         |VFxi....|
  $ : > .hg/cache/rbc-revs-v1

No superfluous rebuilding of cache:
  $ hg log -r "branch(null)&branch(branch)" --debug
  $ f --size --hexdump .hg/cache/rbc-*
  .hg/cache/rbc-names-v1: size=14
  0000: 64 65 66 61 75 6c 74 00 62 72 61 6e 63 68       |default.branch|
  .hg/cache/rbc-revs-v1: size=24
  0000: 66 e5 f5 aa 00 00 00 00 fa 4c 04 e5 00 00 00 00 |f........L......|
  0010: 56 46 78 69 00 00 00 01                         |VFxi....|

  $ cd ..